Eye Dictionary: P
P
pachymetry. This is the measurement of corneal thickness. The cornea is the clear window that makes up the front of the eye and allows light to enter the eye. The corneal thickness is an important measurement for a couple of reasons. An abnormally thin or thick cornea can affect pressure measurements when screening for glaucoma. With LASIK eye surgery, some of the cornea is removed with a laser in order to change the focus of the eye ... if your cornea is too thin to begin with, you might not be a good candidate for LASIK. We measure the cornea with a machine called a "pachymeter" ... it is a small ultrasonic probe that briefly touches the surface of the anesthetized eye. It only takes a few seconds to obtain this measurement and the process is painless. Corneal thickness is a relatively stable measurement and rarely changes with time unless you have problems with corneal swelling such as from Fuchs' dystrophy.
papilledema. This is bilateral swelling of the optic nerves secondary to high intracranial pressure. The brain sits inside the skull and is suspended by membranes, floating in fluid. This fluid is the cerebral spinal fluid (CSF) and is similar to the aqueous fluid in the eyeball itself. If the pressure of this CSF is high, such as in pseudotumor cerebri, this can cause headaches and neurologic changes. Unfortunately, it is very hard to actually measure the pressure inside the skull. One could always drill a hole through the skull and see how fast the water comes out, but for obvious reasons this is not feasible. Instead, a spinal tap is performed. A needle is inserted in the lower back. Since the fluid in the spine is connected to the brain, a neurologist can estimate the brain pressure by measuring the "opening pressure" during the spinal tap. This is not fun either, but is really the only way to truly know the brain pressure. Fortunately, an eye doctor can sometimes estimate the CSF pressure by dilating the eye and looking at the optic disk. The eyeball is a direct extension of the brain ... and the pressure from the brain fluid will travel down the optic nerves and be visible as swelling inside the eye. This swelling is called papilledema. If the pressure is high enough, the nerves will swell and elevate like a volcano, causing blurring of the normally crisp nerve margins.
papilloma. A papilloma is a bump on the eyelid or skin around the eye that looks like a skin tag. These are almost always harmless proliferations of skin cells that have a stuck-on appearance and can be very unsightly. They typically form on the skin around the eyelids and even along the lid margin in the eyelash line. They are sometimes caused by the human papilloma virus (like a wart) but usually they have no known cause. A papilloma can usually be taken off in the office by numbing the skin and cutting them off at the base. Cautery (with a surgical "soldering iron") is usually performed at the base to stop bleeding and to decrease the chance of the papilloma coming back. Cautery gives a surprisingly good cosmetic result, though we have to be careful when working near the edge of the eyelid. If the papilloma is in the lash line, there is a chance that the lashes will not regrow in that spot or they may grow in a funny direction when the area heals (this is called trichiasis).
Pataday. A prescription strength allergy drop that is good for treating itching and swelling around the eyes. This medicine's claim-to-fame is that it is a once-a-day drop. Similar strength allergy drops include Bepreve and Lastacaft.
Patanol. One of the more powerful allergy drops. It is good for itching and swelling around the eyes. This is a prescription medication that has been supplanted by Pataday (which has twice the active ingredient).
patching. Patching an eye shut is useful for several conditions. The most common one is amblyopia, where an eye becomes "lazy" from disuse in childhood. A patch is used to cover the good eye and force the "lazy" eye to work better. Patching is also used for therapeutic effect in cases of eye pain. If you are having extraordinary eye pain from a corneal abrasion the eye can be patched shut. However, I typically avoid prolonged patching in an eye that has an active infection, as bacteria like warm, dark places. Patching can also be useful when an eye won't shut. For example, after retrobulbar block anesthesia (used for difficult or prolonged eye surgery), the eye will not close all the way for several hours. To keep the eye from drying out, the eye is patched shut overnight.
PD. This stands for "pupillary distance," which is the distance between the pupils of each eye. This is an important measurement used in the creation of glasses. See pupillary distance for a more detailed explanation.
phacoemulsification. This is the modern surgical technique for removing cataracts by breaking apart (emulsifying) the lens with ultrasonic vibrations. During cataract surgery, the cloudy lens is removed from the eye. To pull this off, the surgeon first breaks the lens into tiny pieces before vacuuming it out. This is accomplished with a phacoemulsification probe. This ultrasonic technique is a huge improvement as it allows cataract surgery to be performed through a quickly healing microincision. The underlying technology behind phacoemulsification has drastically improved over the past three decades, with less and less energy being required to get the job done. Less energy means safer surgery and quicker healing times. Attempts at using lasers to break up cataracts are being studied, but this hasn't yet been found to work as well.
phakic. A term used to describe an eye that has its natural lens still in place. This is opposed to the term "pseudophakic," which is a person who has a plastic implant in their eye (such as after cataract surgery). If a person has NO lens in their eye (neither their natural lens or cataract implant), we would call this person "aphakic." Aphakia is rare these days, and usually only occurs after trauma or difficulties with prior cataract surgery where a new lens couldn't be implanted.
pheniramine. This is a generic antihistamine drug found in many over-the-counter allergy drops such as Opcon-A and Naphcon-A. While effective, this antihistamine is not as powerful as more modern drugs like ketotifen (found in Alaway and Zaditor) and Pataday.
phenylephrine. This is a dilating drop used during an eye exam to better view the retina. This drop works by stimulating the sympathetic system in order to dilate the pupil. It doesn't cause cycloplegia so there is less problems with blurry vision when dilated. However, this drop does not dilate the pupil enough when used by itself, so it's usually used in conjunction with a cycloplegic like tropicamide. This medication is now being used in over-the-counter decongestants like Sudafed as a replacement for the original pseudoephedrine (which you have to sign for to insure you are not a methamphetamine junkie).
phoropter. This is the machine we use to check your glasses prescription. It is filled with lenses that we flip in front of your eyes, saying "one or two" the whole time as you read the eye chart. The phoropter is the best way to refine an eyeglass prescription, as we can use this machine to detect and fix your astigmatism as well. Unfortunately, some of our patients can't use the phoropter machine because it requires a certain amount of subjective feedback. Young children and the infirm may need to be checked with less precise measurements such as the retinoscope.
photophobia. This is a fancy way of saying pain or sensitivity to light. When an eye is irritated, the iris muscle inside the eye becomes sensitive. The iris is the colored part of our eye - it is a round muscle that dilates and constricts the pupil to control the amount of light entering the eye. This muscle can become inflamed and hurts. With bright lights, the muscle "spasms" and hurts even more. Photophobia can be treated by dilating the eye with cycloplegic eye drops. These drops dilate the pupil, but they also temporarily "paralyze" the iris muscle so it won't spasm. It is like "paralyzing" a broken leg - by immobilizing it in a cast, you don't walk on it, and thus it won't hurt as much. If you are experiencing new photophobia, you should see your eye doctor to insure you don't have a corneal abrasion or more serious internal ocular inflammation such as uveitis.
photoreceptors. After light enters the eye it eventually strikes the retina, which works like the film in a camera. The photoreceptors are the cells within the retina that actually detect light photons and convert them into a signal our body can detect. These photoreceptors come in different varieties. Cones are the cells that detect color and are especially important for our daylight and fine central vision. Rods can only see in black and white, but are highly sensitive and important for night vision and our peripheral vision.
pilocarpine. This is a pupil-constricting eye drop. Pilocarpine has been around for a long time and it makes the pupil constrict by stimulating the iris muscles to contract. In the eye doctor's office, pilocarpine is often used immediately prior to SLT or ALT laser therapy. Pilocarpine is effective in lowering eye pressure, though it is no longer first-line therapy for glaucoma because of the visual side effects (small pupils can make the vision a little blurry).
pinguecula. This is a white or yellow “bump” seen on the white part of the eye. The entire eye is covered by a very thin layer of skin called the conjunctiva. This conjunctiva is very delicate and thin. In fact, you can see red blood vessels coursing through this skin by looking in the mirror. The conjunctiva protects the eye but can become irritated by constant wind and sun exposure. When the skin is irritated, it tends to thicken and become discolored (like a callus on the hand or foot). This creates a discolored bump on the eye. A pinguecula can become irritated and make the eye sensitive. Treatment is usually with artificial tears and sparing use of mild steroid. On rare occasions, surgical excision can be considered, but most pinguecula are mild and only a minor cosmetic nuisance.
pinhole. When we are checking your vision in our office, one of the most common tests we perform is called the "pinhole test." After you read the eye chart wearing your glasses, we recheck your vision while you look through a plastic patch that has little holes punched through it. Many people will actually see better when looking through the pinholes ... reading several lines lower on the eye chart. This pinhole improvement is usually an indicator that your glasses need to be updated. The pinhole test works because it turns your eye from a "focusing telescope" system into a simple "pinhole camera." Pinhole cameras have no lenses and don't need to be focused like a traditional camera ... by letting light into the camera through a tiny pinhole, the image is always in focus. Many small cameras, such as the one in your cell phone, use a pinhole and require little focusing. The eye is much larger, however, and needs to be focused like a telescope.
pink eye. This is a descriptive term for conjunctivitis. The majority of conjunctivitis cases are caused by viral infection (as opposed to allergic or bacterial infection) so the term "pink eye" is more commonly used to describe viral conjunctivitis. See the conjunctivitis entry for more information.
Plaquenil (hydroxychloroquine) is an anti-inflammatory medication that is commonly used in cases of rheumatoid arthritis and lupus. It was originally (and still) used as an anti-malaria drug but has also been found to decrease inflammation in the body. While very effective, this medication can have ocular side effects. Prolonged use can lead to pigmentary changes in the retina and create central vision loss. The vision loss can be detected using a visual field testing machine that focuses on the central 10 degrees of your vision. Color vision seems to be affected first, so often this test is performed with a red filter. As damage occurs, the retina can develop a classic "bulls eye" appearance that can be seen on a dilated eye exam. Despite the potential risk, these visual problems are extremely rare and seem to present more with higher dosages of medicine taken for many years. The longer you are on Plaquenil, the more important regular eye checkups become.
pneumatic retinopexy. This is a procedure used to repair a retinal detachment using a gas bubble. With a retinal detachment, the retina peels off the back of the eye like wallpaper peeling off a wall. To help reapproximate the retina into its normal position, a gas bubble can be injected into the eye. This pushes the retina back in place, holding it down and allowing retinal breaks/holes to be sealed with laser or cryotherapy (cold probe). The benefit to a pneumatic treatment is that it can be performed in the retina specialist's office without requiring surgery. The downside is that this procedure only works if the retina tear is small and located at the top of the eye (because gas bubbles float upwards). Also, the pneumatic retinopexy doesn't always work, and may still require additional retinal surgeries such as vitrectomy or scleral buckle procedure.
POAG. This is the abbreviation for Primary Open Angle Glaucoma. This is the type of glaucoma that most people have, where the eye pressure is chronically elevated leading to gradual optic nerve damage. See chronic open angle glaucoma (COAG) for more details on this topic.
polymyxin. An antibiotic found in combination with other medications such as in Neosporin, Polysporin, and Polytrim.
polymyxin Sulfate/TMP. This is a combination antibiotic drop. The trade name for this combination is Polytrim. This drop is now generic and inexpensive. Long-term use can be irritating to the cornea, however.
Polysporin. This is a combination antibiotic eye drop containing bacitracin and polymyxin. This drug is similar to Neosporin, except that neomycin has been removed (many people have a sensitivity to neomycin).
Polytrim. This is a combination antibiotic eye drop containing polymyxin and trimethoprim. It is available as an inexpensive generic.
polyvinyl alcohol. A synthetic lubricant used in many rewetting drops. It is safe and non-toxic.
Pred-Forte. A popular steroid eye drop. Pred-Forte is the trade name for prednisolone acetate. Steroid eye drops are good at cooling down ocular inflammation caused by iritis or uveitis. This drop is commonly used after cataract surgery, as well, to speed recovery.
prednisolone. Prednisolone acetate is the most common steroid drop we use for the eye. This comes under the trade names Pred-Forte and Econopred. Steroid drops are used to cool down inflammation and are often used after cataract surgery.
presbyopia. This is the process by which you become more reliant on reading glasses as you get older. When we are born, we have a clear lens that sits inside our eye. This lens is flexible and can change shape to help us focus. The lens can "flatten" like a pancake and allow a child to see a distant mountain, or the lens can "round out" like a marble and allow a child to focus on extremely close objects such as a butterfly landing on the nose. This lens shaping ability is called "accommodation." As we get older, the lens begins to stiffen a little bit and doesn't go "round" as easily as it used to. Once we hit 40 years of age, the lens is so rigid that we have a hard time reading things close-up and find ourselves holding books further and further away. As the lens continues to harden we require bifocals or reading glasses for near tasks. This process of lens stiffening and the loss of focal range is called presbyopia and is a normal aging change in our eye.
PreserVision. This is an eye vitamin designed to decrease the progression of macular degeneration. This brand is produced by Bausch & Lomb, but differs from their original Ocuvite product in that the pills are smaller and easier to swallow. The packaging for eye vitamins keeps changing, but as long as you take an AREDS (or AREDS 2) formulation, you should be fine. Remember smokers ... look on the back of the packaging to make sure there isn't any beta-carotene in the vitamins you buy, as this vitamin may increase your risk of lung cancer.
pressure. In regards to the eye, "pressure" usually refers to the intraocular pressure - the pressure inside the eyeball itself. Eye pressure can be measured a number of ways, but all of the methods involve pushing on the eye to estimate the pressure within. This is akin to kicking a car tire with your foot in order to estimate the internal tire pressure. In a doctor's office, pressure is usually measured with applanation tonometry. This is a blue light attached to a weighted mechanism that pushes on the surface of the cornea. Topical numbing drops are used, so the process is quick and painless. Another method to measure pressure is with a hand-held Tono-Pen device. This is an electronic gadget that looks like a large pen or marker and is used to measure the pressure electronically. The Tono-Pen is not terribly accurate, but sometimes it is the only way to check pressure in patients who can't get into the microscope or are bedridden. The final way to check pressure, and the one you may be most familiar with, is the "air puff." This device puffs air at the cornea and measures the surface distortion caused by the shockwave. The air puff is used in some eye offices because it requires little skill to learn and is easy to keep sterile. It is seldom used in medical ophthalmology, however, as the puff is uncomfortable and the measurements may not be as accurate as applanation tonometry (though this is highly debated by some). On our scale, "normal" eye pressure is 10-21, with distribution being skewed toward the higher pressures. High eye pressure is associated with glaucoma and can also be present with inflammation or bleeding inside the eye (from traumatic or after surgery). Low pressure can be seen with wound leaks after surgery and sometimes with internal inflammation like uveitis.
prism. This is a lens ground into a pair of glasses that is designed to bend light and help alleviate double vision. With double vision (also known as diplopia), people see two of the same object. This is usually because of an alignment problem between the eyes such as when someone is cross-eyed. To help alleviate this doubling, prism correction can be ground into a pair of spectacles to bend the light in such a way that the doubling goes back to "normal." Prism glasses are effective for many people, but they have some limitations. Prism adds significant thickness and cost to the glasses. They are also difficult to get "just right" and may require many visits and possible remakes (frustrating for both the patient and the optical shop). Also, some people have alignment problems that vary throughout the day ... they may seem fine in the morning, but as the day progresses their double vision worsens. Prism glasses don't work well in this situation as the correction needed is constantly changing. Finally, some people have double vision that is more pronounced at distance, or near, or when looking in a particular direction. Once again, prism glasses can only correct a 'single' alignment problem and so several pairs of glasses may be required (such as separate distance and reading glasses).
PRK. This stands for "photorefractive keratectomy" and is a laser procedure similar to LASIK used to correct refractive problems like nearsightedness. Like LASIK, an excimer laser is used to sculpt and resurface the shape of the cornea. With LASIK, however, a partial thickness flap is created and flipped up before applying the laser treatment. This flap is then laid back into place and results in more comfort and quicker healing time. With PRK, however, there is no flap and the laser ablation is performed on the surface of the cornea itself. This results in a large corneal abrasion, with more discomfort and a slower healing time than LASIK. PRK is a good option for people with thinner corneas who are not good candidates for the more popular LASIK procedure.
progressive lenses. These are "no line" bifocals. They look like normal glasses, but the further you look down the stronger the bifocal "progressively" becomes. This type of bifocal is useful for active people because you can literally tilt your head to appropriately focus on different objects. For example, you might look through the top part of the progressive to see your car speedometer, and look further down to see your phone. Progressives aren't for everyone, however. Some people don't like them because the bottom part of the glass seems distorted when walking around. Also, the "sweet spot" for crisp reading vision is much smaller than a traditional bifocal, which can be annoying for long periods of reading. They also cost a little more than a traditional bifocal or trifocal. There are several brands of progressive lenses, but generally the Varilux brand is the highest quality model that seems to provide the most comfort for a majority of users.
Prolensa. This is an anti-inflammatory eye drop (an NSAID medication) that is commonly used after cataract surgery to decrease irritation and inflammation. This medicine contains the same medication (bromfenac) as Bromday but with a slightly decreased concentration of the active ingredient. I mainly use this medicine to decrease the chance of retinal swelling after surgery.
proparacaine. This is an anesthetic drop using during an eye exam. This drop numbs the corneal nerves and makes it easier to perform applanation tonometry (pressure checking). We also use this drop before any procedures near the eye, such as foreign body removal. Another drop we use is tetracaine, though we prefer proparacaine in the office as it stings less going in. There aren't really any home applications with this medication ... while it does help with pain, the duration is short (10-20 minutes). Repeated applications of anesthetic are toxic to the cornea and will keep a wound (such as a corneal abrasion) from healing.
proptosis. This is when the eye bulges out. The eye sits inside the eye socket like a scoop of ice cream sitting inside a waffle cone. When the contents of the eye socket swell, there is not a lot of room to expand except forward, so the eye tends to protrude outwards. Proptosis of the eye can occur for many reasons, though the most common is secondary to thyroid eye disease (i.e., Graves' disease) which causes the eye muscles behind the eye to enlarge over time. There are more concerning causes for proptosis, including inflammation, infection, and neoplastic processes (i.e., a tumor). Proptosis needs to be evaluated in the office to rule out these dangerous conditions. Often a CT ("CAT scan") is ordered.
prostaglandin. This is a class of medications used for treating glaucoma. The prostaglandins work by increasing outflow of aqueous fluid from the eye. Examples include Xalatan (latanoprost), Travatan (travoprost), and Lumigan (bimatoprost). These medications are typically dosed once a day. The main complication of these drops is eye redness and irritation, which is why most people take their drops at bedtime so they can sleep through this redness. Other side effects include eyelash growth (woman tend to like this) and pigmentary changes to the skin and iris. All of these findings are quite rare, and prostaglandin drops work so well that they are initial therapy for most people with a new diagnosis of glaucoma. Xalatan was the first prostaglandin eye drop in use - it is now available as generic latanoprost, making this therapy even more affordable.
PRP. This stands for panretinal photocoagulation, and is a laser treatment commonly used for diabetic retinopathy. With diabetes, blood vessels become leaky and the retinal tissue in the eye can become hungry for oxygen because of poor blood delivery. The oxygen-starved retina cells respond by producing protective hormones called VEGF (vascular endothelial growth factor). VEGF causes the formation of new blood vessels, which at first glance ought to be a good idea ... after all, new blood vessels might help feed the hungry retina! Unfortunately, the new blood vessels are abnormal and tend to scar, contract, and bleed easily. This can lead to retinal detachments and vitreous hemorrhage. The abnormal blood vessels can even grow into the trabecular meshwork (the "drain" of the eye) similar to tree roots growing into a house's plumbing. This can lead to acute glaucoma with severe vision loss. This abnormal vessel growth is called neovascularization and it needs to be treated before it gets out of hand. To treat neovascularization, a PRP laser procedure is performed. With this procedure, hundreds (sometimes thousands) of laser spots are burned into the peripheral retina, essentially destroying the peripheral retinal cells. By sacrificing the hungry peripheral retina (where most of the oxygen deprivation is occurring) less VEGF is produced and the neovascularization will stop and even regress. While it may seem barbaric to sacrifice part of the retina in this fashion, the procedure is very important as it saves the more important central vision. Few people notice visual changes after the PRP procedure ... though some complain of a decrease in night vision.
pseudoexfoliation. Pseudoexfoliation syndrome is a common ocular finding, especially if you are of Scandinavian descent. With this condition, a flaky dandruff-like material forms on the surface of your lens/cataract. This material rubs off over a lifetime and can cause glaucoma if the material "clogs the drain" inside your eye. This material also forms on the support strings that hold your lens in position behind your iris. These strings are called zonules, and surround the cataract/lens in a 360-degree ring like springs on a trampoline. With pseudoexfoliation syndrome, the flaky material weakens these springs. If the zonular springs break during surgery, the cataract can fall into the back of the eye and will require removal by a retina specialist (a second operation). We can detect pseudoexfoliation during a routine eye exam.
pseudomonas. This is a water-borne bacteria that commonly sticks to contact lenses and can cause a corneal ulcer. Pseudomonas is the same bacteria that causes "swimmer's ear" and it tends to proliferate in watery environments (such as contact lens solution and within contacts themselves). If this bacteria colonizes the cornea, it can cause a bad corneal ulcer. Pseudomonas infection can be challenging to treat as it tends to be resistant to many of the older antibiotics. For this reason, any infection related to contact lens use needs to be evaluated by an eye doctor and treated with aggressive antibiotics.
pseudophakic. A medical term used to describe an eye that has already had cataract surgery and now contains a plastic or "pseudo" lens implant. Compare this to the term "phakic" (an eye that contains its natural lens) or "aphakic" (an eye that has no lens at all).
pseudotumor cerebri. This is when the pressure inside the cranial cavity (i.e., inside the skull) is too high. The brain sits inside the skull and is suspended in a bath of fluid called the CSF (cerebrospinal fluid). This fluid cushions the brain and keeps it buoyant inside this cramped space. This fluid is constantly being renewed and reabsorbed back into the body. If the drainage of CSF fluid is blocked for some reason, the pressure inside the skull will increase. This creates headaches, and if severe and long-lasting, can create long-term neurologic and visual changes that may be permanent. Pseudotumor cerebri (also called idiopathic intracranial hypertension) can occur for many reasons, such as a reaction to antibiotics, hormonal changes, or a temporary thrombosis of the draining veins inside the skull. We see it most often in younger women of child-bearing years who've gained a little weight recently. Initial diagnosis is often made by an eye doctor as the fluid pressure can transmit to the back of the eye and be seen as swelling of the optic nerve (papilledema) during a dilated eye exam. More definitive diagnosis is made with a spinal tap to measure the "opening pressure." Treatment is first geared at finding the underlying cause. This may involve evaluation with a neurologist and an MRI of the head to look for vein thrombosis. If no obvious cause is found, treatment begins with the oral pill Diamox. This is a water pill that decreases the production of CSF fluid and can lower CSF pressure. Weight loss is also a key in treatment. Sometimes, only a 5 to 10 percent reduction in weight can produce a dramatic improvement in symptoms. If the high pressure continues, then a neurosurgeon may need to insert a surgical drain to remove the excess fluid away from the brain.
pterygium. This is a small yellow-white growth that forms on the eye, starting from the white conjunctival skin, and spreading over the clear cornea. These are harmless growths and common in people with sun exposure or who work outside. The conjunctiva is a very thin layer of skin that covers the eye. This skin can become irritated by a lifetime of sun and wind exposure, causing the skin to thicken and grow a little bit … just like chronic irritation will cause the thickening of skin elsewhere on the body such as a callus on the hands or feet. When skin thickening happens on the eye, we call this a pterygium (or pinguecula if the spot is isolated on the conjunctiva only). Pterygium only occurs on the white of the eye at the three and nine o'clock positions because this is the part of the eye exposed to the elements (i.e., not covered by the eyelids). A pterygium can be aggravating as the eyelid rubs over it with every blink. When irritated, the pterygium can swell, turn red, and cause even more eye irritation. Early treatment usually involves lubrication with artificial tears and sunglasses. If this is not helping, allergy drops and even a mild steroid can be used to cool the eye down. Visine can be used as a shortterm solution but should be used sparingly. If the pterygium persists, gets larger, or approaches the visual axis, than surgical excision can be considered. There are many techniques for removing a pterygium but the most definitive is a “conjunctival autograph.” This involves cutting the pterygium off and sewing/grafting another piece of conjunctival tissue (harvested from underneath the eyelid) in its place. This vastly decreases the chance that the pterygium will reform in the future and gives a good cosmetic result. This is done under topical anesthesia in the operating room.
ptosis. A fancy way to say "droopy eyelid." Ptosis means that the edge of the upper eyelid is actually dropping down, sometimes bad enough to cover the pupil and obstruct vision. Many people with ptosis find themselves tilting their head back or constantly raising their eyebrows in order to lift their eyelids up and see properly. Ptosis can be caused by many things, including congenital ptosis, traumatic injury and neuromuscular disorders like myasthenia gravis. Eyelid drooping can also occur from age stretching of the muscle that holds the eyelid open. Treatment involves surgical tightening of the eyelid retractor muscle. When people describe their eye as drooping, they aren't always talking
about ptosis ... most people actually have dermatochalasis. This is when the skin above the eye becomes lax and droops down over the eyelashes. This is completely different and easier to treat with a blepharoplasty (a surgery to remove this excess skin).
puncta. This is a small drainage hole located on the inner eyelid that drains excess tears into the nose. Normally, the tear film is generated from the inner eyelids and washes down the surface of the eye like a waterfall. The fluid then forms a small "lake" along the lower eyelid. Tears from this lake drain through the punctum (the plural of puncta) and into a drainage canal under the skin. Eventually, the tears flow downthe nasolacrimal duct and empty out into the nose. This pathway explains why people with runny eyes often have a runny nose as well. Some people have a problem with their puncta working correctly. Their puncta may be too small or may have been scarred shut from chronic lid irritation. Aging can cause the lower lid to loosen and rotate outwards so that the puncta is no longer able to reach the tear film at all. Some of these drainage problems can be fixed with surgery (but not easily). Puncta blockage is sometimes a good thing - with dry eye we occasionally block the puncta with temporary punctal plugs and we can even close the puncta permanently using cautery.
punctal occlusion. This is a technique used to decrease the absorption of eye drop medications. Normally when you put eye drops in, the medication drains through the puncta, down the nasolacrimal duct, and into the nose. This is why people have a runny nose when their eyes are teary. Unfortunately, the nose absorbs medicines directly into the blood stream (which is why cocaine is snorted and not swallowed). Some of the medicines we use can have significant systemic absorption and can cause side effects. Overall these side effects are rare, but you can perform punctal occlusion to help avoid the absorption. After you put your eye drops in, immediately close your eyes. Don't blink, as blinking can act as a pump and shoot the medicine right into your nose. Instead, take your fingers and press the bridge of your nose right next to your eyes. Hold this for a good 20 seconds and this will decrease your systemic nose absorption significantly.
punctal plugs. These are small silicone devices inserted into the puncta drainage holes in the eye to allow the tears to last longer and help correct dry eye. Punctal plugs are relatively easy to insert and this can be done right in the exam chair. By slowing down the tear drainage, the ocular surface is better moistened. The plugs are microscopic and can't be easily seen or felt. Unfortunately, the plugs have a tendency to fall out ... this can occur weeks or months after insertion, though I've seen plugs last as long as 10 years in good position. Occasionally, the plugs themselves cause mild irritation and excessive tearing - in these cases we simply remove the plugs using tweezers. More permanent closure of the puncta can be done, but I prefer to use the silicone plugs because they can always be removed later if needed.
pupil. The pupil is the black circle in the middle of the eye. It is actually a hole in the middle of the iris that allows light to enter the back of the eye. The size of the pupil is controlled by the iris muscle in response to ambient lighting. In dark rooms, the pupil enlarges to allow more light to strike the retina. Conversely, in well-lit rooms the pupil constricts to protect the retina and to make the vision look crisper. While the pupil is normally round, there are some conditions that can make the pupil oddly shaped. For example, inflammation of the iris (iritis) can make the pupil edge "stick" to the lens underneath, causing the pupil shape to distort. This distortion is called iris synechiae.
pupillary distance. The pupillary distance is the measured distance between the pupils of both your eyes. When glasses are made, they need to be created to correct for your eye separation. Some people have wide-set eyes and other have near-set eyes, so this can vary widely. This measurement is made by your optician after you pick a new glasses frame, and the measurement is used when your lenses are cut and fitted into the frame. Normally, your "PD" measurement is not measured by your optometrist/ophthalmologist during a clinic visit and so is not written on a glasses prescription (and thus is not part of your medical records). There is a good reason for this - glass "fitting measurements" need to be made by the same person who actually constructs your glasses and the proper fitting of glasses is somewhat dependent upon what frame and glasses style you are actually buying. Some people would like to obtain their PD measurement so they can order glasses online, as overseas spectacles can be found for surprisingly low cost. Local opticians don't like to measure the pupillary distance and just "give out" this measurement for someone else to use. In fact, in some states, they aren't allowed to as it would make them responsible for the glasses (no matter who made them). This reticence on the part of local opticians is not from "greed" or "obstinance," but an attempt to avoid the inevitable backlash from angry online customers. Online glasses are often made to substandard standards in Indonesia/China with lower quality frames. These glasses can be uncomfortable or cause eye strain because of incorrectly cut PD correction and a poor-fitting frame. Also, foreign producers don't measure your vertex distance (the distance from the eye to the back of the glass), bifocal segment height, or adjust your progressive lens placement. If a customer receives a pair of crummy glasses in the mail, there is no easy way to "fix" them online ... so the only recourse is to return to the local optical shop to complain and try to get them adjusted or remade. This creates unnecessary contention between the customer and optical workers who end up spending inordinate amounts of time trying to fix crummy glasses for free that they didn't even make (glasses that might even break during the adjustment process with no way to replace them). This situation is comparable to seeing a local tailor/dressmaker and getting measurements for a dress/tuxedo, ordering an outfit from China, and then complaining to your local tailor/dressmaker when it doesn't fit well. Poorly fit mail-order glasses are more common if you have a "strong" glasses prescription or finicky bifocal requirements. Some people have great success with online sellers, but buyer beware. It is always safer to get your glasses locally ... even if you have to shop around a little to find acceptable costs. This way you can try on the frame to get one that is comfortable, get your eyes measured by the shop that actually uses their own measurements, and have them adjusted afterwards (or even completely remade if necessary) without feeling guilty.
PVD. This is the abbreviation for posterior vitreous detachment. See vitreous detachment for more information on this common cause of flashes and floaters.
papilledema. This is bilateral swelling of the optic nerves secondary to high intracranial pressure. The brain sits inside the skull and is suspended by membranes, floating in fluid. This fluid is the cerebral spinal fluid (CSF) and is similar to the aqueous fluid in the eyeball itself. If the pressure of this CSF is high, such as in pseudotumor cerebri, this can cause headaches and neurologic changes. Unfortunately, it is very hard to actually measure the pressure inside the skull. One could always drill a hole through the skull and see how fast the water comes out, but for obvious reasons this is not feasible. Instead, a spinal tap is performed. A needle is inserted in the lower back. Since the fluid in the spine is connected to the brain, a neurologist can estimate the brain pressure by measuring the "opening pressure" during the spinal tap. This is not fun either, but is really the only way to truly know the brain pressure. Fortunately, an eye doctor can sometimes estimate the CSF pressure by dilating the eye and looking at the optic disk. The eyeball is a direct extension of the brain ... and the pressure from the brain fluid will travel down the optic nerves and be visible as swelling inside the eye. This swelling is called papilledema. If the pressure is high enough, the nerves will swell and elevate like a volcano, causing blurring of the normally crisp nerve margins.
papilloma. A papilloma is a bump on the eyelid or skin around the eye that looks like a skin tag. These are almost always harmless proliferations of skin cells that have a stuck-on appearance and can be very unsightly. They typically form on the skin around the eyelids and even along the lid margin in the eyelash line. They are sometimes caused by the human papilloma virus (like a wart) but usually they have no known cause. A papilloma can usually be taken off in the office by numbing the skin and cutting them off at the base. Cautery (with a surgical "soldering iron") is usually performed at the base to stop bleeding and to decrease the chance of the papilloma coming back. Cautery gives a surprisingly good cosmetic result, though we have to be careful when working near the edge of the eyelid. If the papilloma is in the lash line, there is a chance that the lashes will not regrow in that spot or they may grow in a funny direction when the area heals (this is called trichiasis).
Pataday. A prescription strength allergy drop that is good for treating itching and swelling around the eyes. This medicine's claim-to-fame is that it is a once-a-day drop. Similar strength allergy drops include Bepreve and Lastacaft.
Patanol. One of the more powerful allergy drops. It is good for itching and swelling around the eyes. This is a prescription medication that has been supplanted by Pataday (which has twice the active ingredient).
patching. Patching an eye shut is useful for several conditions. The most common one is amblyopia, where an eye becomes "lazy" from disuse in childhood. A patch is used to cover the good eye and force the "lazy" eye to work better. Patching is also used for therapeutic effect in cases of eye pain. If you are having extraordinary eye pain from a corneal abrasion the eye can be patched shut. However, I typically avoid prolonged patching in an eye that has an active infection, as bacteria like warm, dark places. Patching can also be useful when an eye won't shut. For example, after retrobulbar block anesthesia (used for difficult or prolonged eye surgery), the eye will not close all the way for several hours. To keep the eye from drying out, the eye is patched shut overnight.
PD. This stands for "pupillary distance," which is the distance between the pupils of each eye. This is an important measurement used in the creation of glasses. See pupillary distance for a more detailed explanation.
phacoemulsification. This is the modern surgical technique for removing cataracts by breaking apart (emulsifying) the lens with ultrasonic vibrations. During cataract surgery, the cloudy lens is removed from the eye. To pull this off, the surgeon first breaks the lens into tiny pieces before vacuuming it out. This is accomplished with a phacoemulsification probe. This ultrasonic technique is a huge improvement as it allows cataract surgery to be performed through a quickly healing microincision. The underlying technology behind phacoemulsification has drastically improved over the past three decades, with less and less energy being required to get the job done. Less energy means safer surgery and quicker healing times. Attempts at using lasers to break up cataracts are being studied, but this hasn't yet been found to work as well.
phakic. A term used to describe an eye that has its natural lens still in place. This is opposed to the term "pseudophakic," which is a person who has a plastic implant in their eye (such as after cataract surgery). If a person has NO lens in their eye (neither their natural lens or cataract implant), we would call this person "aphakic." Aphakia is rare these days, and usually only occurs after trauma or difficulties with prior cataract surgery where a new lens couldn't be implanted.
pheniramine. This is a generic antihistamine drug found in many over-the-counter allergy drops such as Opcon-A and Naphcon-A. While effective, this antihistamine is not as powerful as more modern drugs like ketotifen (found in Alaway and Zaditor) and Pataday.
phenylephrine. This is a dilating drop used during an eye exam to better view the retina. This drop works by stimulating the sympathetic system in order to dilate the pupil. It doesn't cause cycloplegia so there is less problems with blurry vision when dilated. However, this drop does not dilate the pupil enough when used by itself, so it's usually used in conjunction with a cycloplegic like tropicamide. This medication is now being used in over-the-counter decongestants like Sudafed as a replacement for the original pseudoephedrine (which you have to sign for to insure you are not a methamphetamine junkie).
phoropter. This is the machine we use to check your glasses prescription. It is filled with lenses that we flip in front of your eyes, saying "one or two" the whole time as you read the eye chart. The phoropter is the best way to refine an eyeglass prescription, as we can use this machine to detect and fix your astigmatism as well. Unfortunately, some of our patients can't use the phoropter machine because it requires a certain amount of subjective feedback. Young children and the infirm may need to be checked with less precise measurements such as the retinoscope.
photophobia. This is a fancy way of saying pain or sensitivity to light. When an eye is irritated, the iris muscle inside the eye becomes sensitive. The iris is the colored part of our eye - it is a round muscle that dilates and constricts the pupil to control the amount of light entering the eye. This muscle can become inflamed and hurts. With bright lights, the muscle "spasms" and hurts even more. Photophobia can be treated by dilating the eye with cycloplegic eye drops. These drops dilate the pupil, but they also temporarily "paralyze" the iris muscle so it won't spasm. It is like "paralyzing" a broken leg - by immobilizing it in a cast, you don't walk on it, and thus it won't hurt as much. If you are experiencing new photophobia, you should see your eye doctor to insure you don't have a corneal abrasion or more serious internal ocular inflammation such as uveitis.
photoreceptors. After light enters the eye it eventually strikes the retina, which works like the film in a camera. The photoreceptors are the cells within the retina that actually detect light photons and convert them into a signal our body can detect. These photoreceptors come in different varieties. Cones are the cells that detect color and are especially important for our daylight and fine central vision. Rods can only see in black and white, but are highly sensitive and important for night vision and our peripheral vision.
pilocarpine. This is a pupil-constricting eye drop. Pilocarpine has been around for a long time and it makes the pupil constrict by stimulating the iris muscles to contract. In the eye doctor's office, pilocarpine is often used immediately prior to SLT or ALT laser therapy. Pilocarpine is effective in lowering eye pressure, though it is no longer first-line therapy for glaucoma because of the visual side effects (small pupils can make the vision a little blurry).
pinguecula. This is a white or yellow “bump” seen on the white part of the eye. The entire eye is covered by a very thin layer of skin called the conjunctiva. This conjunctiva is very delicate and thin. In fact, you can see red blood vessels coursing through this skin by looking in the mirror. The conjunctiva protects the eye but can become irritated by constant wind and sun exposure. When the skin is irritated, it tends to thicken and become discolored (like a callus on the hand or foot). This creates a discolored bump on the eye. A pinguecula can become irritated and make the eye sensitive. Treatment is usually with artificial tears and sparing use of mild steroid. On rare occasions, surgical excision can be considered, but most pinguecula are mild and only a minor cosmetic nuisance.
pinhole. When we are checking your vision in our office, one of the most common tests we perform is called the "pinhole test." After you read the eye chart wearing your glasses, we recheck your vision while you look through a plastic patch that has little holes punched through it. Many people will actually see better when looking through the pinholes ... reading several lines lower on the eye chart. This pinhole improvement is usually an indicator that your glasses need to be updated. The pinhole test works because it turns your eye from a "focusing telescope" system into a simple "pinhole camera." Pinhole cameras have no lenses and don't need to be focused like a traditional camera ... by letting light into the camera through a tiny pinhole, the image is always in focus. Many small cameras, such as the one in your cell phone, use a pinhole and require little focusing. The eye is much larger, however, and needs to be focused like a telescope.
pink eye. This is a descriptive term for conjunctivitis. The majority of conjunctivitis cases are caused by viral infection (as opposed to allergic or bacterial infection) so the term "pink eye" is more commonly used to describe viral conjunctivitis. See the conjunctivitis entry for more information.
Plaquenil (hydroxychloroquine) is an anti-inflammatory medication that is commonly used in cases of rheumatoid arthritis and lupus. It was originally (and still) used as an anti-malaria drug but has also been found to decrease inflammation in the body. While very effective, this medication can have ocular side effects. Prolonged use can lead to pigmentary changes in the retina and create central vision loss. The vision loss can be detected using a visual field testing machine that focuses on the central 10 degrees of your vision. Color vision seems to be affected first, so often this test is performed with a red filter. As damage occurs, the retina can develop a classic "bulls eye" appearance that can be seen on a dilated eye exam. Despite the potential risk, these visual problems are extremely rare and seem to present more with higher dosages of medicine taken for many years. The longer you are on Plaquenil, the more important regular eye checkups become.
pneumatic retinopexy. This is a procedure used to repair a retinal detachment using a gas bubble. With a retinal detachment, the retina peels off the back of the eye like wallpaper peeling off a wall. To help reapproximate the retina into its normal position, a gas bubble can be injected into the eye. This pushes the retina back in place, holding it down and allowing retinal breaks/holes to be sealed with laser or cryotherapy (cold probe). The benefit to a pneumatic treatment is that it can be performed in the retina specialist's office without requiring surgery. The downside is that this procedure only works if the retina tear is small and located at the top of the eye (because gas bubbles float upwards). Also, the pneumatic retinopexy doesn't always work, and may still require additional retinal surgeries such as vitrectomy or scleral buckle procedure.
POAG. This is the abbreviation for Primary Open Angle Glaucoma. This is the type of glaucoma that most people have, where the eye pressure is chronically elevated leading to gradual optic nerve damage. See chronic open angle glaucoma (COAG) for more details on this topic.
polymyxin. An antibiotic found in combination with other medications such as in Neosporin, Polysporin, and Polytrim.
polymyxin Sulfate/TMP. This is a combination antibiotic drop. The trade name for this combination is Polytrim. This drop is now generic and inexpensive. Long-term use can be irritating to the cornea, however.
Polysporin. This is a combination antibiotic eye drop containing bacitracin and polymyxin. This drug is similar to Neosporin, except that neomycin has been removed (many people have a sensitivity to neomycin).
Polytrim. This is a combination antibiotic eye drop containing polymyxin and trimethoprim. It is available as an inexpensive generic.
polyvinyl alcohol. A synthetic lubricant used in many rewetting drops. It is safe and non-toxic.
Pred-Forte. A popular steroid eye drop. Pred-Forte is the trade name for prednisolone acetate. Steroid eye drops are good at cooling down ocular inflammation caused by iritis or uveitis. This drop is commonly used after cataract surgery, as well, to speed recovery.
prednisolone. Prednisolone acetate is the most common steroid drop we use for the eye. This comes under the trade names Pred-Forte and Econopred. Steroid drops are used to cool down inflammation and are often used after cataract surgery.
presbyopia. This is the process by which you become more reliant on reading glasses as you get older. When we are born, we have a clear lens that sits inside our eye. This lens is flexible and can change shape to help us focus. The lens can "flatten" like a pancake and allow a child to see a distant mountain, or the lens can "round out" like a marble and allow a child to focus on extremely close objects such as a butterfly landing on the nose. This lens shaping ability is called "accommodation." As we get older, the lens begins to stiffen a little bit and doesn't go "round" as easily as it used to. Once we hit 40 years of age, the lens is so rigid that we have a hard time reading things close-up and find ourselves holding books further and further away. As the lens continues to harden we require bifocals or reading glasses for near tasks. This process of lens stiffening and the loss of focal range is called presbyopia and is a normal aging change in our eye.
PreserVision. This is an eye vitamin designed to decrease the progression of macular degeneration. This brand is produced by Bausch & Lomb, but differs from their original Ocuvite product in that the pills are smaller and easier to swallow. The packaging for eye vitamins keeps changing, but as long as you take an AREDS (or AREDS 2) formulation, you should be fine. Remember smokers ... look on the back of the packaging to make sure there isn't any beta-carotene in the vitamins you buy, as this vitamin may increase your risk of lung cancer.
pressure. In regards to the eye, "pressure" usually refers to the intraocular pressure - the pressure inside the eyeball itself. Eye pressure can be measured a number of ways, but all of the methods involve pushing on the eye to estimate the pressure within. This is akin to kicking a car tire with your foot in order to estimate the internal tire pressure. In a doctor's office, pressure is usually measured with applanation tonometry. This is a blue light attached to a weighted mechanism that pushes on the surface of the cornea. Topical numbing drops are used, so the process is quick and painless. Another method to measure pressure is with a hand-held Tono-Pen device. This is an electronic gadget that looks like a large pen or marker and is used to measure the pressure electronically. The Tono-Pen is not terribly accurate, but sometimes it is the only way to check pressure in patients who can't get into the microscope or are bedridden. The final way to check pressure, and the one you may be most familiar with, is the "air puff." This device puffs air at the cornea and measures the surface distortion caused by the shockwave. The air puff is used in some eye offices because it requires little skill to learn and is easy to keep sterile. It is seldom used in medical ophthalmology, however, as the puff is uncomfortable and the measurements may not be as accurate as applanation tonometry (though this is highly debated by some). On our scale, "normal" eye pressure is 10-21, with distribution being skewed toward the higher pressures. High eye pressure is associated with glaucoma and can also be present with inflammation or bleeding inside the eye (from traumatic or after surgery). Low pressure can be seen with wound leaks after surgery and sometimes with internal inflammation like uveitis.
prism. This is a lens ground into a pair of glasses that is designed to bend light and help alleviate double vision. With double vision (also known as diplopia), people see two of the same object. This is usually because of an alignment problem between the eyes such as when someone is cross-eyed. To help alleviate this doubling, prism correction can be ground into a pair of spectacles to bend the light in such a way that the doubling goes back to "normal." Prism glasses are effective for many people, but they have some limitations. Prism adds significant thickness and cost to the glasses. They are also difficult to get "just right" and may require many visits and possible remakes (frustrating for both the patient and the optical shop). Also, some people have alignment problems that vary throughout the day ... they may seem fine in the morning, but as the day progresses their double vision worsens. Prism glasses don't work well in this situation as the correction needed is constantly changing. Finally, some people have double vision that is more pronounced at distance, or near, or when looking in a particular direction. Once again, prism glasses can only correct a 'single' alignment problem and so several pairs of glasses may be required (such as separate distance and reading glasses).
PRK. This stands for "photorefractive keratectomy" and is a laser procedure similar to LASIK used to correct refractive problems like nearsightedness. Like LASIK, an excimer laser is used to sculpt and resurface the shape of the cornea. With LASIK, however, a partial thickness flap is created and flipped up before applying the laser treatment. This flap is then laid back into place and results in more comfort and quicker healing time. With PRK, however, there is no flap and the laser ablation is performed on the surface of the cornea itself. This results in a large corneal abrasion, with more discomfort and a slower healing time than LASIK. PRK is a good option for people with thinner corneas who are not good candidates for the more popular LASIK procedure.
progressive lenses. These are "no line" bifocals. They look like normal glasses, but the further you look down the stronger the bifocal "progressively" becomes. This type of bifocal is useful for active people because you can literally tilt your head to appropriately focus on different objects. For example, you might look through the top part of the progressive to see your car speedometer, and look further down to see your phone. Progressives aren't for everyone, however. Some people don't like them because the bottom part of the glass seems distorted when walking around. Also, the "sweet spot" for crisp reading vision is much smaller than a traditional bifocal, which can be annoying for long periods of reading. They also cost a little more than a traditional bifocal or trifocal. There are several brands of progressive lenses, but generally the Varilux brand is the highest quality model that seems to provide the most comfort for a majority of users.
Prolensa. This is an anti-inflammatory eye drop (an NSAID medication) that is commonly used after cataract surgery to decrease irritation and inflammation. This medicine contains the same medication (bromfenac) as Bromday but with a slightly decreased concentration of the active ingredient. I mainly use this medicine to decrease the chance of retinal swelling after surgery.
proparacaine. This is an anesthetic drop using during an eye exam. This drop numbs the corneal nerves and makes it easier to perform applanation tonometry (pressure checking). We also use this drop before any procedures near the eye, such as foreign body removal. Another drop we use is tetracaine, though we prefer proparacaine in the office as it stings less going in. There aren't really any home applications with this medication ... while it does help with pain, the duration is short (10-20 minutes). Repeated applications of anesthetic are toxic to the cornea and will keep a wound (such as a corneal abrasion) from healing.
proptosis. This is when the eye bulges out. The eye sits inside the eye socket like a scoop of ice cream sitting inside a waffle cone. When the contents of the eye socket swell, there is not a lot of room to expand except forward, so the eye tends to protrude outwards. Proptosis of the eye can occur for many reasons, though the most common is secondary to thyroid eye disease (i.e., Graves' disease) which causes the eye muscles behind the eye to enlarge over time. There are more concerning causes for proptosis, including inflammation, infection, and neoplastic processes (i.e., a tumor). Proptosis needs to be evaluated in the office to rule out these dangerous conditions. Often a CT ("CAT scan") is ordered.
prostaglandin. This is a class of medications used for treating glaucoma. The prostaglandins work by increasing outflow of aqueous fluid from the eye. Examples include Xalatan (latanoprost), Travatan (travoprost), and Lumigan (bimatoprost). These medications are typically dosed once a day. The main complication of these drops is eye redness and irritation, which is why most people take their drops at bedtime so they can sleep through this redness. Other side effects include eyelash growth (woman tend to like this) and pigmentary changes to the skin and iris. All of these findings are quite rare, and prostaglandin drops work so well that they are initial therapy for most people with a new diagnosis of glaucoma. Xalatan was the first prostaglandin eye drop in use - it is now available as generic latanoprost, making this therapy even more affordable.
PRP. This stands for panretinal photocoagulation, and is a laser treatment commonly used for diabetic retinopathy. With diabetes, blood vessels become leaky and the retinal tissue in the eye can become hungry for oxygen because of poor blood delivery. The oxygen-starved retina cells respond by producing protective hormones called VEGF (vascular endothelial growth factor). VEGF causes the formation of new blood vessels, which at first glance ought to be a good idea ... after all, new blood vessels might help feed the hungry retina! Unfortunately, the new blood vessels are abnormal and tend to scar, contract, and bleed easily. This can lead to retinal detachments and vitreous hemorrhage. The abnormal blood vessels can even grow into the trabecular meshwork (the "drain" of the eye) similar to tree roots growing into a house's plumbing. This can lead to acute glaucoma with severe vision loss. This abnormal vessel growth is called neovascularization and it needs to be treated before it gets out of hand. To treat neovascularization, a PRP laser procedure is performed. With this procedure, hundreds (sometimes thousands) of laser spots are burned into the peripheral retina, essentially destroying the peripheral retinal cells. By sacrificing the hungry peripheral retina (where most of the oxygen deprivation is occurring) less VEGF is produced and the neovascularization will stop and even regress. While it may seem barbaric to sacrifice part of the retina in this fashion, the procedure is very important as it saves the more important central vision. Few people notice visual changes after the PRP procedure ... though some complain of a decrease in night vision.
pseudoexfoliation. Pseudoexfoliation syndrome is a common ocular finding, especially if you are of Scandinavian descent. With this condition, a flaky dandruff-like material forms on the surface of your lens/cataract. This material rubs off over a lifetime and can cause glaucoma if the material "clogs the drain" inside your eye. This material also forms on the support strings that hold your lens in position behind your iris. These strings are called zonules, and surround the cataract/lens in a 360-degree ring like springs on a trampoline. With pseudoexfoliation syndrome, the flaky material weakens these springs. If the zonular springs break during surgery, the cataract can fall into the back of the eye and will require removal by a retina specialist (a second operation). We can detect pseudoexfoliation during a routine eye exam.
pseudomonas. This is a water-borne bacteria that commonly sticks to contact lenses and can cause a corneal ulcer. Pseudomonas is the same bacteria that causes "swimmer's ear" and it tends to proliferate in watery environments (such as contact lens solution and within contacts themselves). If this bacteria colonizes the cornea, it can cause a bad corneal ulcer. Pseudomonas infection can be challenging to treat as it tends to be resistant to many of the older antibiotics. For this reason, any infection related to contact lens use needs to be evaluated by an eye doctor and treated with aggressive antibiotics.
pseudophakic. A medical term used to describe an eye that has already had cataract surgery and now contains a plastic or "pseudo" lens implant. Compare this to the term "phakic" (an eye that contains its natural lens) or "aphakic" (an eye that has no lens at all).
pseudotumor cerebri. This is when the pressure inside the cranial cavity (i.e., inside the skull) is too high. The brain sits inside the skull and is suspended in a bath of fluid called the CSF (cerebrospinal fluid). This fluid cushions the brain and keeps it buoyant inside this cramped space. This fluid is constantly being renewed and reabsorbed back into the body. If the drainage of CSF fluid is blocked for some reason, the pressure inside the skull will increase. This creates headaches, and if severe and long-lasting, can create long-term neurologic and visual changes that may be permanent. Pseudotumor cerebri (also called idiopathic intracranial hypertension) can occur for many reasons, such as a reaction to antibiotics, hormonal changes, or a temporary thrombosis of the draining veins inside the skull. We see it most often in younger women of child-bearing years who've gained a little weight recently. Initial diagnosis is often made by an eye doctor as the fluid pressure can transmit to the back of the eye and be seen as swelling of the optic nerve (papilledema) during a dilated eye exam. More definitive diagnosis is made with a spinal tap to measure the "opening pressure." Treatment is first geared at finding the underlying cause. This may involve evaluation with a neurologist and an MRI of the head to look for vein thrombosis. If no obvious cause is found, treatment begins with the oral pill Diamox. This is a water pill that decreases the production of CSF fluid and can lower CSF pressure. Weight loss is also a key in treatment. Sometimes, only a 5 to 10 percent reduction in weight can produce a dramatic improvement in symptoms. If the high pressure continues, then a neurosurgeon may need to insert a surgical drain to remove the excess fluid away from the brain.
pterygium. This is a small yellow-white growth that forms on the eye, starting from the white conjunctival skin, and spreading over the clear cornea. These are harmless growths and common in people with sun exposure or who work outside. The conjunctiva is a very thin layer of skin that covers the eye. This skin can become irritated by a lifetime of sun and wind exposure, causing the skin to thicken and grow a little bit … just like chronic irritation will cause the thickening of skin elsewhere on the body such as a callus on the hands or feet. When skin thickening happens on the eye, we call this a pterygium (or pinguecula if the spot is isolated on the conjunctiva only). Pterygium only occurs on the white of the eye at the three and nine o'clock positions because this is the part of the eye exposed to the elements (i.e., not covered by the eyelids). A pterygium can be aggravating as the eyelid rubs over it with every blink. When irritated, the pterygium can swell, turn red, and cause even more eye irritation. Early treatment usually involves lubrication with artificial tears and sunglasses. If this is not helping, allergy drops and even a mild steroid can be used to cool the eye down. Visine can be used as a shortterm solution but should be used sparingly. If the pterygium persists, gets larger, or approaches the visual axis, than surgical excision can be considered. There are many techniques for removing a pterygium but the most definitive is a “conjunctival autograph.” This involves cutting the pterygium off and sewing/grafting another piece of conjunctival tissue (harvested from underneath the eyelid) in its place. This vastly decreases the chance that the pterygium will reform in the future and gives a good cosmetic result. This is done under topical anesthesia in the operating room.
ptosis. A fancy way to say "droopy eyelid." Ptosis means that the edge of the upper eyelid is actually dropping down, sometimes bad enough to cover the pupil and obstruct vision. Many people with ptosis find themselves tilting their head back or constantly raising their eyebrows in order to lift their eyelids up and see properly. Ptosis can be caused by many things, including congenital ptosis, traumatic injury and neuromuscular disorders like myasthenia gravis. Eyelid drooping can also occur from age stretching of the muscle that holds the eyelid open. Treatment involves surgical tightening of the eyelid retractor muscle. When people describe their eye as drooping, they aren't always talking
about ptosis ... most people actually have dermatochalasis. This is when the skin above the eye becomes lax and droops down over the eyelashes. This is completely different and easier to treat with a blepharoplasty (a surgery to remove this excess skin).
puncta. This is a small drainage hole located on the inner eyelid that drains excess tears into the nose. Normally, the tear film is generated from the inner eyelids and washes down the surface of the eye like a waterfall. The fluid then forms a small "lake" along the lower eyelid. Tears from this lake drain through the punctum (the plural of puncta) and into a drainage canal under the skin. Eventually, the tears flow downthe nasolacrimal duct and empty out into the nose. This pathway explains why people with runny eyes often have a runny nose as well. Some people have a problem with their puncta working correctly. Their puncta may be too small or may have been scarred shut from chronic lid irritation. Aging can cause the lower lid to loosen and rotate outwards so that the puncta is no longer able to reach the tear film at all. Some of these drainage problems can be fixed with surgery (but not easily). Puncta blockage is sometimes a good thing - with dry eye we occasionally block the puncta with temporary punctal plugs and we can even close the puncta permanently using cautery.
punctal occlusion. This is a technique used to decrease the absorption of eye drop medications. Normally when you put eye drops in, the medication drains through the puncta, down the nasolacrimal duct, and into the nose. This is why people have a runny nose when their eyes are teary. Unfortunately, the nose absorbs medicines directly into the blood stream (which is why cocaine is snorted and not swallowed). Some of the medicines we use can have significant systemic absorption and can cause side effects. Overall these side effects are rare, but you can perform punctal occlusion to help avoid the absorption. After you put your eye drops in, immediately close your eyes. Don't blink, as blinking can act as a pump and shoot the medicine right into your nose. Instead, take your fingers and press the bridge of your nose right next to your eyes. Hold this for a good 20 seconds and this will decrease your systemic nose absorption significantly.
punctal plugs. These are small silicone devices inserted into the puncta drainage holes in the eye to allow the tears to last longer and help correct dry eye. Punctal plugs are relatively easy to insert and this can be done right in the exam chair. By slowing down the tear drainage, the ocular surface is better moistened. The plugs are microscopic and can't be easily seen or felt. Unfortunately, the plugs have a tendency to fall out ... this can occur weeks or months after insertion, though I've seen plugs last as long as 10 years in good position. Occasionally, the plugs themselves cause mild irritation and excessive tearing - in these cases we simply remove the plugs using tweezers. More permanent closure of the puncta can be done, but I prefer to use the silicone plugs because they can always be removed later if needed.
pupil. The pupil is the black circle in the middle of the eye. It is actually a hole in the middle of the iris that allows light to enter the back of the eye. The size of the pupil is controlled by the iris muscle in response to ambient lighting. In dark rooms, the pupil enlarges to allow more light to strike the retina. Conversely, in well-lit rooms the pupil constricts to protect the retina and to make the vision look crisper. While the pupil is normally round, there are some conditions that can make the pupil oddly shaped. For example, inflammation of the iris (iritis) can make the pupil edge "stick" to the lens underneath, causing the pupil shape to distort. This distortion is called iris synechiae.
pupillary distance. The pupillary distance is the measured distance between the pupils of both your eyes. When glasses are made, they need to be created to correct for your eye separation. Some people have wide-set eyes and other have near-set eyes, so this can vary widely. This measurement is made by your optician after you pick a new glasses frame, and the measurement is used when your lenses are cut and fitted into the frame. Normally, your "PD" measurement is not measured by your optometrist/ophthalmologist during a clinic visit and so is not written on a glasses prescription (and thus is not part of your medical records). There is a good reason for this - glass "fitting measurements" need to be made by the same person who actually constructs your glasses and the proper fitting of glasses is somewhat dependent upon what frame and glasses style you are actually buying. Some people would like to obtain their PD measurement so they can order glasses online, as overseas spectacles can be found for surprisingly low cost. Local opticians don't like to measure the pupillary distance and just "give out" this measurement for someone else to use. In fact, in some states, they aren't allowed to as it would make them responsible for the glasses (no matter who made them). This reticence on the part of local opticians is not from "greed" or "obstinance," but an attempt to avoid the inevitable backlash from angry online customers. Online glasses are often made to substandard standards in Indonesia/China with lower quality frames. These glasses can be uncomfortable or cause eye strain because of incorrectly cut PD correction and a poor-fitting frame. Also, foreign producers don't measure your vertex distance (the distance from the eye to the back of the glass), bifocal segment height, or adjust your progressive lens placement. If a customer receives a pair of crummy glasses in the mail, there is no easy way to "fix" them online ... so the only recourse is to return to the local optical shop to complain and try to get them adjusted or remade. This creates unnecessary contention between the customer and optical workers who end up spending inordinate amounts of time trying to fix crummy glasses for free that they didn't even make (glasses that might even break during the adjustment process with no way to replace them). This situation is comparable to seeing a local tailor/dressmaker and getting measurements for a dress/tuxedo, ordering an outfit from China, and then complaining to your local tailor/dressmaker when it doesn't fit well. Poorly fit mail-order glasses are more common if you have a "strong" glasses prescription or finicky bifocal requirements. Some people have great success with online sellers, but buyer beware. It is always safer to get your glasses locally ... even if you have to shop around a little to find acceptable costs. This way you can try on the frame to get one that is comfortable, get your eyes measured by the shop that actually uses their own measurements, and have them adjusted afterwards (or even completely remade if necessary) without feeling guilty.
PVD. This is the abbreviation for posterior vitreous detachment. See vitreous detachment for more information on this common cause of flashes and floaters.