Eye Dictionary A
A
accommodation. Accommodation is the process by which the eye focuses to see near objects. A normal eye, that is to say, an eye that is neither nearsighted nor farsighted, is naturally focused to see distant objects clearly. To see close-up objects, such as when reading, the flexible lens inside the eye changes shape and becomes "rounder." This process is called accommodation and is quite versatile when young. After the age of 40, however, our lens becomes stiff and accommodation becomes more challenging. We lose our ability to accommodate and we become more dependent on glasses and bifocals with time. This loss of accommodation is called presbyopia.
(Common Misspellings: acommodation, accomodation, accomada, acco, acomo.)
acetazolamide. An oral water pill that is used to treat glaucoma. This pill is a diuretic and will dehydrate the body, but it will also dehydrate the eye and decrease eye pressure. This medication is also known as Diamox and is normally used in cases of extremely high eye pressure where we've exhausted our topical eye drop options, or used immediately after other eye surgery to avoid pressure spikes. Don't confuse this with acetomenophine (Tylenol). If you switch these, you might be up all night peeing instead of curing your headache. This pill is also used for people going to high altitudes to avoid mountain sickness. Side effects are minor but can include tingling sensations in the fingers/toes and carbonated soft drinks may taste odd.
acular. This is an eye drop in the NSAID class of medicines. It is an anti-inflammatory drop with a mechanism similar to Advil or Motrin. It is occasionally used to help with ocular discomfort but mainly used after eye surgery. This class of medicines is good at decreasing the chance of macular edema (retinal swelling) after cataract surgery. It can sting a little going in, however.
acute glaucoma. Acute glaucoma is when the pressure inside the eye goes up suddenly. This usually occurs because of a sudden closure of the drainage "angle" inside the eye. With no drainage, the aqueous humor fluid builds up and causes a spike in eye pressure that can lead to rapid vision loss. Symptoms include extreme eye pain along with nausea and halos seen around lights. Treatment is geared toward lowering the pressure and "breaking the attack," often with a laser, eye drops, and diuretic pills like Diamox. Acute glaucoma is less common in the USA as most people with glaucoma have chronic "open-angle" glaucoma. If an eye appears to be at risk for having an attack, then we will sometimes perform a prophylactic laser procedure called a laser peripheral iridotomy (LPI) to decrease the likelihood of this problem.
acyclovir. An antiviral pill used for viral infections such as shingles (chicken pox) and herpetic eye disease. This medication is cheap and effective, but requires a lot of pills to get the correct dosing. A similar medicine we use is called Valtrex (valacyclovir). Some people with these recurring infections will take a maintenance dose of acyclovir to decrease the chance of a new outbreak.
Adie's pupil. This is a neurologic disorder in which one eye becomes dilated. Most patients have no symptoms or visual complaints, but a friend points out that one of their pupils is now much larger than the other. Also, the pupil does not seem to constrict normally with light. An Adie's pupil usually occurs from damage to one of the nerve clusters behind the eye (inside the eye socket) that controls pupil constriction. This damage can occur from an otherwise harmless viral infection such as a common cold. The problem is usually temporary and goes away after a few months. The opposite condition is called Horner's syndrome. Horner's causes pupil constriction and is potentially dangerous.
after-cataract. This is a cloudy membrane that forms on the back surface of an implant lens inside the eye after cataract surgery. This opacity can form months or years after a successful cataract operation and can cause blur and glare symptoms (similar to the original cataract). These "after cataracts" are not a complication from cataract surgery, but rather a continued proliferation of tissue inside the eye (similar to scar tissue). After-cataracts are easy to treat with a laser. A YAG capsulotomy can be performed to create a hole through the opaque membrane. This is a simple, painless procedure, and once performed the "after cataract" does not typically reoccur.
Alaway. An effective over-the-counter allergy drop. Alaway contains the medicine ketotifen and is usually used twice a day. Allergy drops are good for itching and swelling, and can make the eye feel less sensitive. Alaway and Zaditor (which contains the same active ingredient) are two of my favorite over-the-counter allergy drops.
allergic conjunctivitis. The eyes are particularly sensitive to environmental allergens. Symptoms are usually bilateral, with both eyes being itchy and puffy. Eyelid swelling can be so bad that you look like you've been in a fight ... we call these "allergic shiners." Treatment for allergic conjunctivitis involves cool compresses, antihistamine allergy drops, and occasionally mild steroid drops.
(Common Misspellings: conj,coj)
allergy drops. Allergy drops are commonly used to treat ocular itching and swelling. There are several types of allergy drops on the market. The first generation antihistamine drops like Opcon-A are effective but tend to give short-lived relief. Second generation antihistamines like laway/Zaditor are more effective and what I recommend for most of my patients. Prescription strength allergy drops are also available such as Bepreve, Pataday, and Lastacaft.
Alphagan. A glaucoma drop used to lower eye pressure. This drop went generic so many people have switched to generic brimonidine or moved up to Alphagan P.
Alphagan P. This is a glaucoma eye drop designed to lower eye pressure. It is actually a "new" formulation of brimonidine that has a lower concentration of active drug and a less harsh preservative in it. Despite the decreased concentration, the drop appears to have the same efficacy as the old Alphagan but with less irritating side effects.
Alrex. A mild steroid eye drop. Useful in cases of ocular inflammation and irritation. This drop has the same ingredient (loteprednol) as Lotemax but with a third of the steroid concentration. By reducing the steroid concentration, this decreases the chance of untoward reactions such as premature cataract formation and glaucoma pressure spikes.
ALT. This stands for Argon Laser Trabeculoplasty and is a laser procedure designed to lower the eye pressure in people with glaucoma. This procedure involves using a "hot" laser to burn spots into the trabecular meshwork (the drainage filter of the eye). By doing this, scar tissue forms that opens up the meshwork and creates better flow. While effective and well tolerated, the pressure improvements of ALT tend to wear off in a couple of years. The procedure can only be done once because of the scar formation. ALT is largely being replaced by a similar procedure called SLT. With SLT a "cold" YAG laser is used to create similar spots on the trabecular meshwork but instead of creating heatinduced scars, the drainage cells are merely stimulated. This promotes better flow through the drain without creating permanent tissue damage. This means that SLT can be repeated if it wears off. SLT is slowly becoming first-line therapy for many doctors treating glaucoma.
amblyopia. Also known as "lazy eye." Amblyopia occurs at a young age from disuse when an eye doesn't see well. A child's visual nervous system is still developing until age seven. If during this developmental period, one eye has poorer vision, the "brain wiring" for that eye does not form as strongly as the better eye. This can occur because of early nearsightedness or early farsightedness or from other visual problems such as congenital cataract. This imbalance can also occur if the eyes are in poor alignment (like being cross-eyed). If detected early, amblyopia can be reversed. This is typically accomplished with glasses and patching therapy - by patching the "good eye" closed, this forces the lazy eye to "work" and reform its wiring. There is no way to fix a lazy eye in adulthood as the brain wiring has already formed and the amblyopic eye will never see quite as well.
(Common Misspellings: ambl,abmly)
amiodarone. This is a commonly used oral medication that is used to help with abnormal rhythms of the heart (arrhythmias). While effective, amiodarone can occasionally cause changes in the eye. One of these changes is "corneal verticillata," which are pigment deposits in the clear cornea that can be seen with the slit lamp microscope. These corneal changes rarely cause any appreciable vision problems, but if severe may prompt a change in medication.
amphotericin B. An antifungal medicine that can be compounded (see fortified antibiotics) and used to treat fungal eye infections. There are not many antifungal eye medications out there - the only other eye drop easily available is Natamycin.
Amsler grid. A checkered pattern used at home for detecting retinal distortions, such as from macular degeneration or an epiretinal membrane. To use, a patient is instructed to look at the central dot while covering an eye. If the surrounding lines are missing or look distorted, then the surface of the retina (which acts like "film in a camera") may be distorted as well. This prompts further evaluation and retinal scans like an OCT to find these problems.
anesthetic drops. There are several drops we use to anesthetize the surface of the eye. The most common one is called proparacaine, though we occasionally use tetracaine. These drops are very similar to the "novacaine" that a dentist uses ... but fortunately we don't have to use a needle to apply it! Numbing drops make it easier to check eyes pressure using applanation tonometry. We also use these drops prior to cataract surgery to minimize discomfort. Unfortunately, anesthetic eye drops are not safe for home use. The medications are toxic to the corneal surface when used repeatedly and will keep surface wounds from healing. For pain, we prescribe ointments, bandage contact lenses, and can even patch an eye shut if needed (see patching).
angle. In regards to the eye, the "angle" usually refers to the drainage angle inside the eye where excess ocular fluid (aqueous) is reabsorbed back into the blood stream. This angle is located at the intersection of the iris and the white sclera of the eye ... in other words, in a 360-degree ring where the "white" of the eye meets the "colored part" of the eye. If this angle closes down, then you can have an angle-closure glaucoma, also known as acute glaucoma.
anisocoria. This is when the pupils are of unequal size. Many people have slightly different sized pupils and this is considered normal. Large differences between the eye is not normal, however. See dilated pupil for more information.
anterior chamber. This is the fluid-filled space in the front part of the eye, located immediately behind the cornea but in front of the iris. This "chamber" is filled with clear aqueous fluid and easy to examine by the doctor using the slit lamp microscope in the office. In cases of trauma or iritis, the anterior chamber may be filled with inflammatory cells that can be detected in the office. In more severe cases of trauma, blood can fill this space ... this is called a hyphema. If you have acute glaucoma, the anterior chamber can be shallow as the aqueous fluid cannot drain out properly.
(Common Misspellings: anter)
antibiotic. This usually refers to a drop or pill that is designed to kill or decrease the proliferation of bacteria. The eye is well protected from infection by the conjunctiva and the corneal epithelium. In addition, the tear film contains antimicrobials and the tear flow itself tends to wash away pathogens. The eye also harbors a host of non-pathogenic bacteria that competitively prohibit new bacteria growth. However, these eye defenses can be breached by trauma, improper tearing, or contact lens wear and lead to an infection. Topical antibiotics work best for the eye given the avascular nature of the cornea.
anti-VEGF. This is a class of medicines that are designed to combat neovascularization inside the eye and decrease blood vessel leakage. They are usually used for treating problems like macular edema, caused by wet macular degeneration, though occasionally they are used for treating swelling from other sources such as diabetic retinopathy or central retinal vein occlusion. These medicines work by decreasing leakage of fluid across abnormal blood vessels in the retina. The original anti-VEGF medication used was the injection medicine Avastin which was originally formulated for combating colon cancer. Lucentis and Eylea are newer anti-VEGF medications that may be more effective with less systemic side effects, but are quite costly when compared to Avastin. Refer to the entries on VEGF and neovascularization to better understand how these medications work.
aphakia. This is when the natural lens has been removed from the eye (such as after cataract surgery) but has not been replaced with a new lens implant. In the early days of eye surgery, cataracts were removed but not replaced with anything. The vision was better but "aphakic people" required thick coke-bottle glasses to see well. Today, most people receive a new implant so aphakia is rare. Most people with aphakic eyes have had some kind of trauma or complicated cataract surgery that precludes the placement of a modern lens implant.
(Common Misspellings: aph,afak)
applanation tonometry. This is a method for checking the pressure inside the eye. The eyeball is a closed ball of fluid so that there is no good way to measure the internal pressure of the eyeball directly. However, we can estimate the eye pressure by pushing on the surface of the eye and feeling "how hard" is seems. This is similar to kicking a car tire to estimate the air pressure inside. With applanation tonometry, a flat probe is pushed onto the surface of the cornea (the clear window that makes up the front of the eye). The probe is pushed hard enough to flatten a small round area of the cornea. By looking at the size of the circle flattened, and examining the amount of pressure used, the internal eye pressure can be calculated. The machine we use for this is called a Goldmann Applanation Tonometer. It is attached to the slit lamp microscope and it looks like a blue light when in use. You don't feel this measurement as we use anesthetic drops ahead of time.
aqueous. The aqueous "humor" is the fluid that fills the front part of the eye (the anterior chamber). This clear fluid maintains the shape of the eye and affects the eye pressure. Glaucoma can occur if the pressure gets too high, and most glaucoma treatments are geared toward regulating the production and drainage of the aqueous fluid. Several structures in the eye, such as the cornea and lens, contain no blood vessels and rely on the aqueous humor to provide them with nutritional support.
arcus senilis. This is a white haze or ring on the cornea that occurs with age. The cornea is the clear window that makes up the front of the eye. This living tissue has no blood vessels running through it because it needs to be perfectly clear. To get its nutrition, the cornea depends upon the tear film on the outside, the aqueous fluid on the inside, and blood vessels on the sclera (the white of the eye) that run right up to the edge of cornea before stopping. Lipid and cholesterol fats travel in our blood stream, and over a lifetime, can leach out of the blood vessels and deposit themselves in a ring in the cornea. This white ring is called arcus senilis and is a normal aging change that has no effect on vision. When seen in only one eye (or in a young person) we start looking into other problems such as circulation or cholesterol abnormalities.
AREDS Study. This stands for the Age-Related Eye Disease Study. This large study was conducted to study the effects of vitamin supplements in slowing the progression of macular degeneration. The study showed that certain antioxidants were more helpful, such as Vitamin A, Vitamin C, and Vitamin E and the metals zinc and copper (cupric acid). While these vitamins are found in a healthy diet, the high doses used in the AREDS trial were much higher than normal multivitamin tablets and are difficult to obtain through normal food intake. Therefore, additional oral pill supplements are recommended in anyone with signs of macular degeneration. While vitamins are generally safe, there are a few caveats you should keep in mind. If you are a
smoker, you should NOT take any supplements with Vitamin A (betacarotene) as this has been associated with higher rates of lung cancer. You really shouldn't be smoking, as smoking has been found to speed macular degeneration in its own right. Also, there is some controversy over whether dietary zinc might slightly increase the risk of prostate cancer for men, but most authorities seem to think it safe. Both of these problems are being studied in the AREDS 2 Study.
AREDS 2 Study. This is the latest study searching for additional supplements that slow down macular degeneration progression. In the original AREDS Study, researchers found that Vitamin A (beta-carotene), C, E and the metals zinc and copper were helpful in slowing the progression of vision loss. However, there are many more supplements out there that have been theorized to be healthy for the eye. The AREDS2 clinical trial finished in 2012 and the results are only now coming to light. It appears that the omega-3 fatty acids (DHA and EPA) had little effect on the eye, despite their known cardiac and stroke benefits. However, the plant pigments lutein and zeaxanthin were found to be helpful and may be a good replacement for beta-carotene (which is contraindicated in smokers because of increased lung cancer risk). AREDS 2 vitamins are beginning to show up on the shelves and are safe for most people. Vitamin packaging can be confusing. If you are a smoker or have had lung cancer, be sure to read the contents and avoid any vitamins with beta-carotene.
ARMD. This stands for Age-Related Macular Degeneration and is just another way of saying macular degeneration. See the entry on macular degeneration for more details.
artificial tears. These are rewetting drops that can be bought over the counter and used for dry eye. Artificial tears are produced by many manufacturers and are essentially all the same. The only real difference between them is what preservative is used to keep the drops sterile. This preservative is crucial for keeping the drops fresh and free of environmental bacteria. However, the preservative itself (especially BAK) can be irritating to the eye if the drops are used too often. Preservativefree artificial tears are available that eliminate this problem. They come in single-use disposable plastic dispensers and can be used as often as needed.
A-scan. This is a type of ultrasound used on the eye and is primarily used to measure the length of the eyeball. This measurement is needed prior to cataract surgery so that we can calculate the correct implant power for the replacement lens. A-scan ultrasound can be very precise but only focuses on one parameter - the length of the eye. This is in contrast to B-scan ultrasound, which actually produces an image of the interior structures of the eye (and is more akin to the fetal ultrasound
used in pregnancy).
asteroid hyalosis. This is a harmless condition where calcium soap deposits form inside the vitreous fluid that fills the back of the eye. During an eye exam, these little specks glow brightly under the microscope - in fact, the inside of the eye looks like a blizzard or snow globe. Despite the impressive microscopic appearance, these deposits cause little visual symptoms though some people complain of more floaters than normal. Asteroid hyalosis is primarily an incidental finding seen during an eye exam and not an indicator of any problems. If there are enough floaters to obstruct vision, a vitrectomy surgery could be considered, but this is rarely indicated. Asteroid hyalosis is mainly of interest to eye doctors.
asthenopia. This is a fancy word for eye strain or discomfort. There are many causes for eye strain, including incorrect glasses, motility problems (the eyes out of alignment), or even from surface irritation such as dry eye.
astigmatism. This is when the eye is oval in shape. Normally the surface of the cornea is perfectly round like a basketball. Some people's cornea is shaped more like a football ... that is to say, the cornea is steep along one axis and shallow along the other. This is called astigmatism and is completely normal. It is easy to fix astigmatism using glasses, as the "mirror image" of your eye's football can be ground into your glasses and aligned to give good vision. There are also toric contacts that can fix astigmatism though they are a little harder to fit as contacts spin on the surface of the eye. Finally, there are now toric implants used in cataract surgery. These implants have the football shape ground in ahead of time. During surgery, we rotate this implant inside the eye until it perfectly balances out and eliminates your eye's natural astigmatism.
atropine. A powerful dilating drop. This drop is so powerful, in fact, that your eye may be dilated for a week after its use. This is also a cycloplegia drop typically given in cases of ocular inflammation (iritis) to help with pain control by temporarily paralyzing the iris muscle inside the eye. The drop is often used after retina surgery for similar reasons, but also because atropine appears to have some anti-inflammatory properties in its own right. Young children can take a long time to dilate, so this drop is occasionally used at home to dilate a child prior to their eye exam. The blurring effect can also be used as a kind of "chemical patching" in cases of amblyopia (lazy eye) - especially useful in a child who won't wear an eye patch. Atropine is one of the oldest eye medications out there and has been used since Victorian times when it was used to dilate women's eyes to make them look more striking. It is extracted from the belladonna . thus, comes the saying "belle of the ball." It is on the generic list at most pharmacies and is inexpensive.
Augmentin. An antibiotic pill that is good for skin, sinus, and innerear infections. It can cause mild diarrhea. Another oral medication is Keflex.
autorefractor. This is a machine used in the eye doctor's office to help determine your glasses prescription. While not as accurate as actual refraction (the process by which you read the eye chart through the phoropter machine), the autorefractor provides a useful starting point that can be further refined in the exam room.
Avastin. This is an injection medicine used to treat wet macular degeneration and sometimes used for other causes of macular edema such as diabetic retinopathy. Avastin was originally developed for systemic use to treat colon cancer. However, its anti-VEGF properties are good at targeting abnormal retinal blood vessels and so it is commonly used in the eye as well. Avastin is a wonder drug, and compared to comparable injectables (Lucentis, Macugen, Eylea), it is extremely cheap. The reason behind this cost is that Avastin was originally packaged in much larger dosage for systemic delivery for the entire body. Compounding pharmacies can split this large dosage into increments more suitable for ocular injection and the cost comes down to about 50 dollars a treatment. Compare this to medicines approved and marketed specifically for the eye which cost around $2,000 per treatment.
AzaSite. This is an antibiotic drop containing azithromycin. You may know azithromycin in its pill form, where it is marketed as the "Z-pack" and is good for treating lung infections and pneumonia. AzaSite has been packaged as an eye drop and is sometimes used in treating blepharitis (chronic eyelid inflammation). The drop may have some anti-inflammatory properties, and it may help the eyelid meibomian glands flow better and improve eye comfort.
azithromycin. An antibiotic pill commonly used for pneumonia and upper respiratory infections. It is available as a dose pack called a "Zpack." This medicine has been formulated into an eye drop called AzaSite for topical use for eye infection and for the treatment of blepharitis (chronic eyelid inflammation).
Azopt. A glaucoma eye drop used to lower eye pressure by slowing the production of aqueous fluid inside the eye. This is a carbonic anhydrase inhibitor. Other glaucoma drops in this class include Trusopt and dorzolamide.
(Common Misspellings: acommodation, accomodation, accomada, acco, acomo.)
acetazolamide. An oral water pill that is used to treat glaucoma. This pill is a diuretic and will dehydrate the body, but it will also dehydrate the eye and decrease eye pressure. This medication is also known as Diamox and is normally used in cases of extremely high eye pressure where we've exhausted our topical eye drop options, or used immediately after other eye surgery to avoid pressure spikes. Don't confuse this with acetomenophine (Tylenol). If you switch these, you might be up all night peeing instead of curing your headache. This pill is also used for people going to high altitudes to avoid mountain sickness. Side effects are minor but can include tingling sensations in the fingers/toes and carbonated soft drinks may taste odd.
acular. This is an eye drop in the NSAID class of medicines. It is an anti-inflammatory drop with a mechanism similar to Advil or Motrin. It is occasionally used to help with ocular discomfort but mainly used after eye surgery. This class of medicines is good at decreasing the chance of macular edema (retinal swelling) after cataract surgery. It can sting a little going in, however.
acute glaucoma. Acute glaucoma is when the pressure inside the eye goes up suddenly. This usually occurs because of a sudden closure of the drainage "angle" inside the eye. With no drainage, the aqueous humor fluid builds up and causes a spike in eye pressure that can lead to rapid vision loss. Symptoms include extreme eye pain along with nausea and halos seen around lights. Treatment is geared toward lowering the pressure and "breaking the attack," often with a laser, eye drops, and diuretic pills like Diamox. Acute glaucoma is less common in the USA as most people with glaucoma have chronic "open-angle" glaucoma. If an eye appears to be at risk for having an attack, then we will sometimes perform a prophylactic laser procedure called a laser peripheral iridotomy (LPI) to decrease the likelihood of this problem.
acyclovir. An antiviral pill used for viral infections such as shingles (chicken pox) and herpetic eye disease. This medication is cheap and effective, but requires a lot of pills to get the correct dosing. A similar medicine we use is called Valtrex (valacyclovir). Some people with these recurring infections will take a maintenance dose of acyclovir to decrease the chance of a new outbreak.
Adie's pupil. This is a neurologic disorder in which one eye becomes dilated. Most patients have no symptoms or visual complaints, but a friend points out that one of their pupils is now much larger than the other. Also, the pupil does not seem to constrict normally with light. An Adie's pupil usually occurs from damage to one of the nerve clusters behind the eye (inside the eye socket) that controls pupil constriction. This damage can occur from an otherwise harmless viral infection such as a common cold. The problem is usually temporary and goes away after a few months. The opposite condition is called Horner's syndrome. Horner's causes pupil constriction and is potentially dangerous.
after-cataract. This is a cloudy membrane that forms on the back surface of an implant lens inside the eye after cataract surgery. This opacity can form months or years after a successful cataract operation and can cause blur and glare symptoms (similar to the original cataract). These "after cataracts" are not a complication from cataract surgery, but rather a continued proliferation of tissue inside the eye (similar to scar tissue). After-cataracts are easy to treat with a laser. A YAG capsulotomy can be performed to create a hole through the opaque membrane. This is a simple, painless procedure, and once performed the "after cataract" does not typically reoccur.
Alaway. An effective over-the-counter allergy drop. Alaway contains the medicine ketotifen and is usually used twice a day. Allergy drops are good for itching and swelling, and can make the eye feel less sensitive. Alaway and Zaditor (which contains the same active ingredient) are two of my favorite over-the-counter allergy drops.
allergic conjunctivitis. The eyes are particularly sensitive to environmental allergens. Symptoms are usually bilateral, with both eyes being itchy and puffy. Eyelid swelling can be so bad that you look like you've been in a fight ... we call these "allergic shiners." Treatment for allergic conjunctivitis involves cool compresses, antihistamine allergy drops, and occasionally mild steroid drops.
(Common Misspellings: conj,coj)
allergy drops. Allergy drops are commonly used to treat ocular itching and swelling. There are several types of allergy drops on the market. The first generation antihistamine drops like Opcon-A are effective but tend to give short-lived relief. Second generation antihistamines like laway/Zaditor are more effective and what I recommend for most of my patients. Prescription strength allergy drops are also available such as Bepreve, Pataday, and Lastacaft.
Alphagan. A glaucoma drop used to lower eye pressure. This drop went generic so many people have switched to generic brimonidine or moved up to Alphagan P.
Alphagan P. This is a glaucoma eye drop designed to lower eye pressure. It is actually a "new" formulation of brimonidine that has a lower concentration of active drug and a less harsh preservative in it. Despite the decreased concentration, the drop appears to have the same efficacy as the old Alphagan but with less irritating side effects.
Alrex. A mild steroid eye drop. Useful in cases of ocular inflammation and irritation. This drop has the same ingredient (loteprednol) as Lotemax but with a third of the steroid concentration. By reducing the steroid concentration, this decreases the chance of untoward reactions such as premature cataract formation and glaucoma pressure spikes.
ALT. This stands for Argon Laser Trabeculoplasty and is a laser procedure designed to lower the eye pressure in people with glaucoma. This procedure involves using a "hot" laser to burn spots into the trabecular meshwork (the drainage filter of the eye). By doing this, scar tissue forms that opens up the meshwork and creates better flow. While effective and well tolerated, the pressure improvements of ALT tend to wear off in a couple of years. The procedure can only be done once because of the scar formation. ALT is largely being replaced by a similar procedure called SLT. With SLT a "cold" YAG laser is used to create similar spots on the trabecular meshwork but instead of creating heatinduced scars, the drainage cells are merely stimulated. This promotes better flow through the drain without creating permanent tissue damage. This means that SLT can be repeated if it wears off. SLT is slowly becoming first-line therapy for many doctors treating glaucoma.
amblyopia. Also known as "lazy eye." Amblyopia occurs at a young age from disuse when an eye doesn't see well. A child's visual nervous system is still developing until age seven. If during this developmental period, one eye has poorer vision, the "brain wiring" for that eye does not form as strongly as the better eye. This can occur because of early nearsightedness or early farsightedness or from other visual problems such as congenital cataract. This imbalance can also occur if the eyes are in poor alignment (like being cross-eyed). If detected early, amblyopia can be reversed. This is typically accomplished with glasses and patching therapy - by patching the "good eye" closed, this forces the lazy eye to "work" and reform its wiring. There is no way to fix a lazy eye in adulthood as the brain wiring has already formed and the amblyopic eye will never see quite as well.
(Common Misspellings: ambl,abmly)
amiodarone. This is a commonly used oral medication that is used to help with abnormal rhythms of the heart (arrhythmias). While effective, amiodarone can occasionally cause changes in the eye. One of these changes is "corneal verticillata," which are pigment deposits in the clear cornea that can be seen with the slit lamp microscope. These corneal changes rarely cause any appreciable vision problems, but if severe may prompt a change in medication.
amphotericin B. An antifungal medicine that can be compounded (see fortified antibiotics) and used to treat fungal eye infections. There are not many antifungal eye medications out there - the only other eye drop easily available is Natamycin.
Amsler grid. A checkered pattern used at home for detecting retinal distortions, such as from macular degeneration or an epiretinal membrane. To use, a patient is instructed to look at the central dot while covering an eye. If the surrounding lines are missing or look distorted, then the surface of the retina (which acts like "film in a camera") may be distorted as well. This prompts further evaluation and retinal scans like an OCT to find these problems.
anesthetic drops. There are several drops we use to anesthetize the surface of the eye. The most common one is called proparacaine, though we occasionally use tetracaine. These drops are very similar to the "novacaine" that a dentist uses ... but fortunately we don't have to use a needle to apply it! Numbing drops make it easier to check eyes pressure using applanation tonometry. We also use these drops prior to cataract surgery to minimize discomfort. Unfortunately, anesthetic eye drops are not safe for home use. The medications are toxic to the corneal surface when used repeatedly and will keep surface wounds from healing. For pain, we prescribe ointments, bandage contact lenses, and can even patch an eye shut if needed (see patching).
angle. In regards to the eye, the "angle" usually refers to the drainage angle inside the eye where excess ocular fluid (aqueous) is reabsorbed back into the blood stream. This angle is located at the intersection of the iris and the white sclera of the eye ... in other words, in a 360-degree ring where the "white" of the eye meets the "colored part" of the eye. If this angle closes down, then you can have an angle-closure glaucoma, also known as acute glaucoma.
anisocoria. This is when the pupils are of unequal size. Many people have slightly different sized pupils and this is considered normal. Large differences between the eye is not normal, however. See dilated pupil for more information.
anterior chamber. This is the fluid-filled space in the front part of the eye, located immediately behind the cornea but in front of the iris. This "chamber" is filled with clear aqueous fluid and easy to examine by the doctor using the slit lamp microscope in the office. In cases of trauma or iritis, the anterior chamber may be filled with inflammatory cells that can be detected in the office. In more severe cases of trauma, blood can fill this space ... this is called a hyphema. If you have acute glaucoma, the anterior chamber can be shallow as the aqueous fluid cannot drain out properly.
(Common Misspellings: anter)
antibiotic. This usually refers to a drop or pill that is designed to kill or decrease the proliferation of bacteria. The eye is well protected from infection by the conjunctiva and the corneal epithelium. In addition, the tear film contains antimicrobials and the tear flow itself tends to wash away pathogens. The eye also harbors a host of non-pathogenic bacteria that competitively prohibit new bacteria growth. However, these eye defenses can be breached by trauma, improper tearing, or contact lens wear and lead to an infection. Topical antibiotics work best for the eye given the avascular nature of the cornea.
anti-VEGF. This is a class of medicines that are designed to combat neovascularization inside the eye and decrease blood vessel leakage. They are usually used for treating problems like macular edema, caused by wet macular degeneration, though occasionally they are used for treating swelling from other sources such as diabetic retinopathy or central retinal vein occlusion. These medicines work by decreasing leakage of fluid across abnormal blood vessels in the retina. The original anti-VEGF medication used was the injection medicine Avastin which was originally formulated for combating colon cancer. Lucentis and Eylea are newer anti-VEGF medications that may be more effective with less systemic side effects, but are quite costly when compared to Avastin. Refer to the entries on VEGF and neovascularization to better understand how these medications work.
aphakia. This is when the natural lens has been removed from the eye (such as after cataract surgery) but has not been replaced with a new lens implant. In the early days of eye surgery, cataracts were removed but not replaced with anything. The vision was better but "aphakic people" required thick coke-bottle glasses to see well. Today, most people receive a new implant so aphakia is rare. Most people with aphakic eyes have had some kind of trauma or complicated cataract surgery that precludes the placement of a modern lens implant.
(Common Misspellings: aph,afak)
applanation tonometry. This is a method for checking the pressure inside the eye. The eyeball is a closed ball of fluid so that there is no good way to measure the internal pressure of the eyeball directly. However, we can estimate the eye pressure by pushing on the surface of the eye and feeling "how hard" is seems. This is similar to kicking a car tire to estimate the air pressure inside. With applanation tonometry, a flat probe is pushed onto the surface of the cornea (the clear window that makes up the front of the eye). The probe is pushed hard enough to flatten a small round area of the cornea. By looking at the size of the circle flattened, and examining the amount of pressure used, the internal eye pressure can be calculated. The machine we use for this is called a Goldmann Applanation Tonometer. It is attached to the slit lamp microscope and it looks like a blue light when in use. You don't feel this measurement as we use anesthetic drops ahead of time.
aqueous. The aqueous "humor" is the fluid that fills the front part of the eye (the anterior chamber). This clear fluid maintains the shape of the eye and affects the eye pressure. Glaucoma can occur if the pressure gets too high, and most glaucoma treatments are geared toward regulating the production and drainage of the aqueous fluid. Several structures in the eye, such as the cornea and lens, contain no blood vessels and rely on the aqueous humor to provide them with nutritional support.
arcus senilis. This is a white haze or ring on the cornea that occurs with age. The cornea is the clear window that makes up the front of the eye. This living tissue has no blood vessels running through it because it needs to be perfectly clear. To get its nutrition, the cornea depends upon the tear film on the outside, the aqueous fluid on the inside, and blood vessels on the sclera (the white of the eye) that run right up to the edge of cornea before stopping. Lipid and cholesterol fats travel in our blood stream, and over a lifetime, can leach out of the blood vessels and deposit themselves in a ring in the cornea. This white ring is called arcus senilis and is a normal aging change that has no effect on vision. When seen in only one eye (or in a young person) we start looking into other problems such as circulation or cholesterol abnormalities.
AREDS Study. This stands for the Age-Related Eye Disease Study. This large study was conducted to study the effects of vitamin supplements in slowing the progression of macular degeneration. The study showed that certain antioxidants were more helpful, such as Vitamin A, Vitamin C, and Vitamin E and the metals zinc and copper (cupric acid). While these vitamins are found in a healthy diet, the high doses used in the AREDS trial were much higher than normal multivitamin tablets and are difficult to obtain through normal food intake. Therefore, additional oral pill supplements are recommended in anyone with signs of macular degeneration. While vitamins are generally safe, there are a few caveats you should keep in mind. If you are a
smoker, you should NOT take any supplements with Vitamin A (betacarotene) as this has been associated with higher rates of lung cancer. You really shouldn't be smoking, as smoking has been found to speed macular degeneration in its own right. Also, there is some controversy over whether dietary zinc might slightly increase the risk of prostate cancer for men, but most authorities seem to think it safe. Both of these problems are being studied in the AREDS 2 Study.
AREDS 2 Study. This is the latest study searching for additional supplements that slow down macular degeneration progression. In the original AREDS Study, researchers found that Vitamin A (beta-carotene), C, E and the metals zinc and copper were helpful in slowing the progression of vision loss. However, there are many more supplements out there that have been theorized to be healthy for the eye. The AREDS2 clinical trial finished in 2012 and the results are only now coming to light. It appears that the omega-3 fatty acids (DHA and EPA) had little effect on the eye, despite their known cardiac and stroke benefits. However, the plant pigments lutein and zeaxanthin were found to be helpful and may be a good replacement for beta-carotene (which is contraindicated in smokers because of increased lung cancer risk). AREDS 2 vitamins are beginning to show up on the shelves and are safe for most people. Vitamin packaging can be confusing. If you are a smoker or have had lung cancer, be sure to read the contents and avoid any vitamins with beta-carotene.
ARMD. This stands for Age-Related Macular Degeneration and is just another way of saying macular degeneration. See the entry on macular degeneration for more details.
artificial tears. These are rewetting drops that can be bought over the counter and used for dry eye. Artificial tears are produced by many manufacturers and are essentially all the same. The only real difference between them is what preservative is used to keep the drops sterile. This preservative is crucial for keeping the drops fresh and free of environmental bacteria. However, the preservative itself (especially BAK) can be irritating to the eye if the drops are used too often. Preservativefree artificial tears are available that eliminate this problem. They come in single-use disposable plastic dispensers and can be used as often as needed.
A-scan. This is a type of ultrasound used on the eye and is primarily used to measure the length of the eyeball. This measurement is needed prior to cataract surgery so that we can calculate the correct implant power for the replacement lens. A-scan ultrasound can be very precise but only focuses on one parameter - the length of the eye. This is in contrast to B-scan ultrasound, which actually produces an image of the interior structures of the eye (and is more akin to the fetal ultrasound
used in pregnancy).
asteroid hyalosis. This is a harmless condition where calcium soap deposits form inside the vitreous fluid that fills the back of the eye. During an eye exam, these little specks glow brightly under the microscope - in fact, the inside of the eye looks like a blizzard or snow globe. Despite the impressive microscopic appearance, these deposits cause little visual symptoms though some people complain of more floaters than normal. Asteroid hyalosis is primarily an incidental finding seen during an eye exam and not an indicator of any problems. If there are enough floaters to obstruct vision, a vitrectomy surgery could be considered, but this is rarely indicated. Asteroid hyalosis is mainly of interest to eye doctors.
asthenopia. This is a fancy word for eye strain or discomfort. There are many causes for eye strain, including incorrect glasses, motility problems (the eyes out of alignment), or even from surface irritation such as dry eye.
astigmatism. This is when the eye is oval in shape. Normally the surface of the cornea is perfectly round like a basketball. Some people's cornea is shaped more like a football ... that is to say, the cornea is steep along one axis and shallow along the other. This is called astigmatism and is completely normal. It is easy to fix astigmatism using glasses, as the "mirror image" of your eye's football can be ground into your glasses and aligned to give good vision. There are also toric contacts that can fix astigmatism though they are a little harder to fit as contacts spin on the surface of the eye. Finally, there are now toric implants used in cataract surgery. These implants have the football shape ground in ahead of time. During surgery, we rotate this implant inside the eye until it perfectly balances out and eliminates your eye's natural astigmatism.
atropine. A powerful dilating drop. This drop is so powerful, in fact, that your eye may be dilated for a week after its use. This is also a cycloplegia drop typically given in cases of ocular inflammation (iritis) to help with pain control by temporarily paralyzing the iris muscle inside the eye. The drop is often used after retina surgery for similar reasons, but also because atropine appears to have some anti-inflammatory properties in its own right. Young children can take a long time to dilate, so this drop is occasionally used at home to dilate a child prior to their eye exam. The blurring effect can also be used as a kind of "chemical patching" in cases of amblyopia (lazy eye) - especially useful in a child who won't wear an eye patch. Atropine is one of the oldest eye medications out there and has been used since Victorian times when it was used to dilate women's eyes to make them look more striking. It is extracted from the belladonna . thus, comes the saying "belle of the ball." It is on the generic list at most pharmacies and is inexpensive.
Augmentin. An antibiotic pill that is good for skin, sinus, and innerear infections. It can cause mild diarrhea. Another oral medication is Keflex.
autorefractor. This is a machine used in the eye doctor's office to help determine your glasses prescription. While not as accurate as actual refraction (the process by which you read the eye chart through the phoropter machine), the autorefractor provides a useful starting point that can be further refined in the exam room.
Avastin. This is an injection medicine used to treat wet macular degeneration and sometimes used for other causes of macular edema such as diabetic retinopathy. Avastin was originally developed for systemic use to treat colon cancer. However, its anti-VEGF properties are good at targeting abnormal retinal blood vessels and so it is commonly used in the eye as well. Avastin is a wonder drug, and compared to comparable injectables (Lucentis, Macugen, Eylea), it is extremely cheap. The reason behind this cost is that Avastin was originally packaged in much larger dosage for systemic delivery for the entire body. Compounding pharmacies can split this large dosage into increments more suitable for ocular injection and the cost comes down to about 50 dollars a treatment. Compare this to medicines approved and marketed specifically for the eye which cost around $2,000 per treatment.
AzaSite. This is an antibiotic drop containing azithromycin. You may know azithromycin in its pill form, where it is marketed as the "Z-pack" and is good for treating lung infections and pneumonia. AzaSite has been packaged as an eye drop and is sometimes used in treating blepharitis (chronic eyelid inflammation). The drop may have some anti-inflammatory properties, and it may help the eyelid meibomian glands flow better and improve eye comfort.
azithromycin. An antibiotic pill commonly used for pneumonia and upper respiratory infections. It is available as a dose pack called a "Zpack." This medicine has been formulated into an eye drop called AzaSite for topical use for eye infection and for the treatment of blepharitis (chronic eyelid inflammation).
Azopt. A glaucoma eye drop used to lower eye pressure by slowing the production of aqueous fluid inside the eye. This is a carbonic anhydrase inhibitor. Other glaucoma drops in this class include Trusopt and dorzolamide.