Eye Dictionary: S-T
S
sclera. This is the white part of the eye. The sclera is the firm wall of the eye that gives the eye its shape and structure. Made of collagen fiber, the sclera is relatively tough. It is also continuous with the clear cornea in the front of the eye. The sclera is covered by a thin layer of skin called the conjunctiva. This clear skin covers the eyeball and contains small blood vessels you can see in the mirror. When you are looking at the "white" of your eye, you are looking through this conjunctival skin at the scleral wall of the eye itself.
scleral buckle. This is asurgical procedure used to repair a retinal detachment. With this procedure, a silicone band is inserted around the eye and cinched tight, like abelt around a waistline. This decreases traction forces inside the eye which allows the retina to lay back in its normal position. Scleral buckle surgery is widely performed and used to be the only viable treatment for retinal detachments. Other techniques have arisen such as vitrectomy and pneumatic retinopexy. Every retina specialist has their own surgical preferences and the technique chosen depends upon circumstances and the location of retinal breaks. Some retina surgeons seem to be leaning toward vitrectomy as improvements in retina instrumentation have made vitrectomies fast and less traumatic. There are benefits and risks in all these retinal procedures. One potential problem with a scleral buckle is that the silicone band tends to make the eye physically longer and this can change the overall refractive error of the eye. It's fairly common for the eye to become extremely nearsighted. This can be fixed with a change in glasses prescription, but if the difference between the eyes becomes too great, the glasses won't be comfortable to wear and a contact lens might be required instead. Fortunately, most of these balance issues can be fixed during cataract surgery or with LASIK if they become too bothersome. Less easy to fix is the potential for strabismus, where the buckle makes the eyes slightly out of alignment, causing double vision. Retinal detachments are serious, so these risks are acceptable given the alternative (a blind eye).
second sight. This is the phenomenon where cataract formation seems to make the vision "better" by improving your glasses prescription. A cataract is when the lens inside your eye becomes cloudy. An enlarging cataract usually causes glare problems, but the cataract growth can also change the eye's overall "glasses prescription" as well. For some people, this change is in a bad direction and they require stronger and stronger glasses to see well. For a lucky few, the change is in a "good" direction and actually decreases the reliance on spectacles. The eyes aren't really "improving," it just seems that way. One of the signs that perhaps a cataract is getting worse is when the glasses prescription starts changing rapidly.
shingles. This is a re-outbreak of chicken pox. When people get chickenpox as a child, the viral infection can hit large parts of the body. The body's immune system fights back and eradicates the virus. However, the virus is not completely gone, but usually sits dormant in the base of the nerves in the spine and head. Later in life, as the immune system slows down, the virus can reactivate and run back out the nerve and affect the skin. This outbreak is called "shingles" or "zoster" and it usually affects a single dermatome (strip of skin) in the body. If the fifth cranial nerve of the head (called the trigeminal nerve) is affected, the shingles outbreak can occur on the face. Often the forehead and scalp are involved with painful lesions and swelling of the skin. If the eye is affected this can lead to corneal scaring and long-term vision problems. We usually treat a shingles outbreak with an antiviral medication like Valtrex or acyclovir. If these medications are started within three days of initial symptoms, the medications have been found to limit duration of illness and decrease the chance of long-term sensation/pain problems. It's important to see an eye doctor if there is any eye redness or change in vision as the eye may require treatment as well.
Simbrinza. This is a new combination glaucoma drop combining two separate pressure-lowering medicines - brinzolamide (Azopt) and brimonidine (Alphagan). Combination drugs are useful for decreasing the number of actual drops you must take. The downside, however, is their premium cost is not covered by your prescription drug plan.
Similasan. This is a brand of herbal eye drop therapies. Given the shear number of FDA-approved and scientifically studied eye medicines available, I never bother with this. Someone must be using this, however, since the company is still in business and the product is still on shelves.
sixth nerve palsy. This is a paralysis of the sixth cranial nerve. This nerve controls a single eye muscle, the abducens muscle, which is responsible for making the eye look to the side. If this muscle stops working the eye turns inward (crosseyed) and has a hard time moving outwards. Most people complain of a sideby-side horizontal double vision. Like all cranial nerve palsies, there are many potential causes for an abducens palsy. The most common cause is microvascular injury from diabetes or hypertension. You can think of this like a miniature "stroke" to the nerve. Other potential causes are mass lesions (tumors or aneurysms) and high intracranial pressure such as from pseudotumor cerebri. Most sixth nerve palsies are self-limited and improve after a few months. Ophthalmologists used to watch these palsies for spontaneous improvement, but in this day and age of MRI imaging, we tend to image everyone with a new palsy to rule out the dangerous stuff.
slit lamp microscope. This is a microscope used by an eye doctor to look at the eye. The eye microscope is unique when compared to a traditional microscopes. For one thing, the microscope has been turned on its side so that people can be examined without having to lie down flat. Also, the light-source used can be narrowed to a very narrow beam of light. This light can be angled into the eye to form an illuminated cross-section of the eye ... just like how a CAT scan takes cross-section x-ray slices. The eye is the only place in the body that blood vessels and nerves can be seen without opaque skin blocking the view. With a dilated eye exam, the optic nerve (a direct extension off the brain) can be viewed in great detail. Certain systemic conditions can be observed and diagnosed using the slit lamp microscope. For example, diabetes can cause micro-bleeding in the retina (diabetic retinopathy) and inflammatory conditions like rheumatoid arthritis can cause internal ocular inflammation (uveitis). With the slitlamp microscope and careful technique, individual white blood cells floating in the eye can be detected.
SLT. This is the abbreviation for Selective Laser Trabeculoplasty - it is a glaucoma laser procedure designed to lower eye pressure in a nondestructive way. Most cases of glaucoma involve microscopic blockage of the trabecular meshwork drain inside the eye. If the internal ocular fluid doesn't drain properly, aqueous fluid pressure builds up and causes gradual damage over time. There are many ways to lower eye pressure. Glaucoma eye drops work to open the drain chemically and you can think of them like "Drano" for the eye. Glaucoma surgery is very effective, but it is also a big production and associated with some morbidity. Fortunately, glaucoma laser therapies have come a long way. ALT was the original laser procedure. With ALT, a "hot" laser was directed at the eye's drain and used to create scars in the trabecular meshwork. These scars helped open drainage tissue to manually get things flowing. This worked really well to lower pressure, but unfortunately the effect is short-lived and tended to wear off after a couple of years. ALT can't be repeated as there is only so much scar tissue the eye can suffer. SLT is a newer laser technology that some people have dubbed as a "cold laser." SLT doesn't create scaring inside the eye, but instead is used to irritate and stimulate the trabecular drainage cells to flow better. The benefit to SLT is that no permanent scars are created and the procedure can be repeated if it wears off. The downside to SLT is that is doesn't work for everyone. We like to think of SLT as an adjunctive therapy to eye drops ... if you are taking a single glaucoma drop, SLT therapy may be able to get you off it. If you are already on glaucoma drops and your eye pressure is creeping up, an SLT treatment may keep you from needing an additional drop or surgery. The procedure takes about 5 minutes and is painless with little recovery time.
Snellen chart. This is the eye chart used by American eye doctors for measuring vision. The letters on this eye chart are calibrated based on distance measurements, comparing your vision to someone with "perfect" eyes. For example, if you have a vision of 20/60 ... this means that the letters you can barely see when standing 20 feet from the chart can be easily seen by a "perfect-eyed person" standing a full 60 feet away from the same chart! In the USA and many European countries, legal driving vision is 20/50 and you are considered legally blind if your corrected vision is 20/200 or worse. The Snellen chart is calibrated to be 20 feet from the exam chair you are sitting in ... but few eye doctors have exam rooms this long. To offset this, mirrors are used to obtain the full 20-foot distance.
Soothe. This is a brand name rewetting drops from Bausch & Lomb. Competing brands are Systane, Blink, GenTeal, and Refresh.
squinting. Squinting of the eyes is common, and is commonly done in an attempt to see better. If the eye has refractive error (like nearsightedness or farsightedness) the images entering the eye do not focus well on the retina and look blurry. By squinting and looking through the eyelashes, you can actually see a little clearer. The eyelashes turn the eye into a pinhole camera, which improves depth of focus and improves vision. Squinting is not a good long-term vision solution (obviously), so glasses or contacts are prescribed to improve vision and decrease eye strain. See the entry on pinholes to understand this concept better.
steroid. Steroids are useful in ophthalmology for treating ocular inflammation. This is particularly useful after cataract surgery and with internal ocular inflammation such as uveitis. Steroids can also be useful for decreasing corneal scarring, such as after a trauma or infection. Care must be used with steroids, however, as they can exacerbate infections - viruses and bacteria love steroids as it "makes them strong." While short term topical steroids are relatively safe, long-term use may cause some problems. Some people are "steroid responders" and their eye pressure ends to go up while on topical eye drops. This pressure change usually takes a few weeks to kick in and goes away after a couple of weeks off the drops. Steroids are also associated with premature cataract formation, though this is more of an issue with oral steroids. Common steroids used by eye doctors are prednisolone acetate (Pred-Forte or Econopred), loteprednol (Lotemax and Alrex) and dexamethasone (usually found in combination drops like Tobradex).
strabismus. This is a descriptive term used by eye doctors to describe eyes that are in poor alignment with each other. For example, someone with strabismus may be cross-eyed, wall-eyed, or have an eye that drifts upwards. Some people have strabismus that occurs only when tired and others have a problems with double vision only with reading. There are many causes for strabismus, from congenital motor problems to cranial nerve palsies. Strabismus needs to be evaluated by an eye doctor for an appropriate workup. If the alignment problem persists, strabismus surgery is sometimes recommended. Prism glasses are another option, especially for long-standing strabismus in adults.
strabismus surgery. This is surgery to correct ocular misalignment (strabismus). Most strabismus surgery is performed on toddlers to correct alignment problems such as crossed-eyes. This surgery involves the weakening or strengthening of eye muscles by shortening them or changing their insertion points on the edge of the eye. While most ophthalmologists have trained in performing strabismus surgery, these days the procedure is mostly carried out by pediatric ophthalmologists who have more practice with this type of surgery. Many pediatric ophthalmologists perform adult strabismus surgery as well.
stye. A stye is an infection of one of the oil or sweat glands running along the eyelid. Styes are tender to the touch and may form an abscess or pus layer that is visible through the skin as a "white head." The treatment for a stye typically begins with warm compresses and gentle massage. While a "pimple" elsewhere on the body can usually be "popped" or "lanced" with little ill effect, I strongly discourage being too aggressive with the eyelid as the eyeball underneath is a sensitive structure and easily injured. Also, some doctors think that aggressive eyelid squeezing may actually spread infection to adjacent skin and make the stye worse. If warm compresses and gentle massage aren't working, the stye may require topical or oral antibiotics, and even lancing. A stye is a bit different than a chalazion, which is a blockage of the deeper meibomian glands that tends to be painless.
subconjunctival hemorrhage. This is an extremely red eye that occurs when a blood vessel on the surface of the eye ruptures. The white part of the eye (the sclera) is covered by a very thin layer of skin called the conjunctiva. You can see this skin when looking in a mirror, as red blood vessels course through it and look like "lines" on the eye. If one of these blood vessels bursts for some reason, such as after a cough or sneeze, blood will track underneath the conjunctiva and make the eye look extremely red. It only takes a few drops of blood to make the eye look bright red and this can look quite alarming in the mirror. A subconjunctival hemorrhage is almost always harmless, but warrants a check to make sure there is no bleeding inside the eye (a hyphema or vitreous hemorrhage) and to make sure the cornea isn't drying out.
sulfa allergy. Several medicines are sulfa based and can cause problems for people allergic to sulfa drugs. The main culprits are the carbonic anhydrase inhibitors used for glaucoma. Examples of these glaucoma drops include dorzolamide, Trusopt, Azopt, and Cosopt. Also, the water pill Diamox (acetazolamide) is sometimes used for treating advanced glaucoma, but is sulfa-based as well. Sulfacetamide is an antibiotic eye drop (also called Bleph-10) that can also cause sulfa problems, but I rarely prescribe this, given the plethora of good antibiotic alternatives.
sulfacetamide sodium 10%. Also known by the trade name Bleph-10, this is an antibiotic eye drop that has gone generic and can be found on the Walmart $4 list. This drug is sulfa-based and not good for those people with sulfa allergy.
Systane. This is a brand name rewetting drop made by Alcon. Competing brands include Soothe, Blink, GenTeal, and Refresh.
scleral buckle. This is asurgical procedure used to repair a retinal detachment. With this procedure, a silicone band is inserted around the eye and cinched tight, like abelt around a waistline. This decreases traction forces inside the eye which allows the retina to lay back in its normal position. Scleral buckle surgery is widely performed and used to be the only viable treatment for retinal detachments. Other techniques have arisen such as vitrectomy and pneumatic retinopexy. Every retina specialist has their own surgical preferences and the technique chosen depends upon circumstances and the location of retinal breaks. Some retina surgeons seem to be leaning toward vitrectomy as improvements in retina instrumentation have made vitrectomies fast and less traumatic. There are benefits and risks in all these retinal procedures. One potential problem with a scleral buckle is that the silicone band tends to make the eye physically longer and this can change the overall refractive error of the eye. It's fairly common for the eye to become extremely nearsighted. This can be fixed with a change in glasses prescription, but if the difference between the eyes becomes too great, the glasses won't be comfortable to wear and a contact lens might be required instead. Fortunately, most of these balance issues can be fixed during cataract surgery or with LASIK if they become too bothersome. Less easy to fix is the potential for strabismus, where the buckle makes the eyes slightly out of alignment, causing double vision. Retinal detachments are serious, so these risks are acceptable given the alternative (a blind eye).
second sight. This is the phenomenon where cataract formation seems to make the vision "better" by improving your glasses prescription. A cataract is when the lens inside your eye becomes cloudy. An enlarging cataract usually causes glare problems, but the cataract growth can also change the eye's overall "glasses prescription" as well. For some people, this change is in a bad direction and they require stronger and stronger glasses to see well. For a lucky few, the change is in a "good" direction and actually decreases the reliance on spectacles. The eyes aren't really "improving," it just seems that way. One of the signs that perhaps a cataract is getting worse is when the glasses prescription starts changing rapidly.
shingles. This is a re-outbreak of chicken pox. When people get chickenpox as a child, the viral infection can hit large parts of the body. The body's immune system fights back and eradicates the virus. However, the virus is not completely gone, but usually sits dormant in the base of the nerves in the spine and head. Later in life, as the immune system slows down, the virus can reactivate and run back out the nerve and affect the skin. This outbreak is called "shingles" or "zoster" and it usually affects a single dermatome (strip of skin) in the body. If the fifth cranial nerve of the head (called the trigeminal nerve) is affected, the shingles outbreak can occur on the face. Often the forehead and scalp are involved with painful lesions and swelling of the skin. If the eye is affected this can lead to corneal scaring and long-term vision problems. We usually treat a shingles outbreak with an antiviral medication like Valtrex or acyclovir. If these medications are started within three days of initial symptoms, the medications have been found to limit duration of illness and decrease the chance of long-term sensation/pain problems. It's important to see an eye doctor if there is any eye redness or change in vision as the eye may require treatment as well.
Simbrinza. This is a new combination glaucoma drop combining two separate pressure-lowering medicines - brinzolamide (Azopt) and brimonidine (Alphagan). Combination drugs are useful for decreasing the number of actual drops you must take. The downside, however, is their premium cost is not covered by your prescription drug plan.
Similasan. This is a brand of herbal eye drop therapies. Given the shear number of FDA-approved and scientifically studied eye medicines available, I never bother with this. Someone must be using this, however, since the company is still in business and the product is still on shelves.
sixth nerve palsy. This is a paralysis of the sixth cranial nerve. This nerve controls a single eye muscle, the abducens muscle, which is responsible for making the eye look to the side. If this muscle stops working the eye turns inward (crosseyed) and has a hard time moving outwards. Most people complain of a sideby-side horizontal double vision. Like all cranial nerve palsies, there are many potential causes for an abducens palsy. The most common cause is microvascular injury from diabetes or hypertension. You can think of this like a miniature "stroke" to the nerve. Other potential causes are mass lesions (tumors or aneurysms) and high intracranial pressure such as from pseudotumor cerebri. Most sixth nerve palsies are self-limited and improve after a few months. Ophthalmologists used to watch these palsies for spontaneous improvement, but in this day and age of MRI imaging, we tend to image everyone with a new palsy to rule out the dangerous stuff.
slit lamp microscope. This is a microscope used by an eye doctor to look at the eye. The eye microscope is unique when compared to a traditional microscopes. For one thing, the microscope has been turned on its side so that people can be examined without having to lie down flat. Also, the light-source used can be narrowed to a very narrow beam of light. This light can be angled into the eye to form an illuminated cross-section of the eye ... just like how a CAT scan takes cross-section x-ray slices. The eye is the only place in the body that blood vessels and nerves can be seen without opaque skin blocking the view. With a dilated eye exam, the optic nerve (a direct extension off the brain) can be viewed in great detail. Certain systemic conditions can be observed and diagnosed using the slit lamp microscope. For example, diabetes can cause micro-bleeding in the retina (diabetic retinopathy) and inflammatory conditions like rheumatoid arthritis can cause internal ocular inflammation (uveitis). With the slitlamp microscope and careful technique, individual white blood cells floating in the eye can be detected.
SLT. This is the abbreviation for Selective Laser Trabeculoplasty - it is a glaucoma laser procedure designed to lower eye pressure in a nondestructive way. Most cases of glaucoma involve microscopic blockage of the trabecular meshwork drain inside the eye. If the internal ocular fluid doesn't drain properly, aqueous fluid pressure builds up and causes gradual damage over time. There are many ways to lower eye pressure. Glaucoma eye drops work to open the drain chemically and you can think of them like "Drano" for the eye. Glaucoma surgery is very effective, but it is also a big production and associated with some morbidity. Fortunately, glaucoma laser therapies have come a long way. ALT was the original laser procedure. With ALT, a "hot" laser was directed at the eye's drain and used to create scars in the trabecular meshwork. These scars helped open drainage tissue to manually get things flowing. This worked really well to lower pressure, but unfortunately the effect is short-lived and tended to wear off after a couple of years. ALT can't be repeated as there is only so much scar tissue the eye can suffer. SLT is a newer laser technology that some people have dubbed as a "cold laser." SLT doesn't create scaring inside the eye, but instead is used to irritate and stimulate the trabecular drainage cells to flow better. The benefit to SLT is that no permanent scars are created and the procedure can be repeated if it wears off. The downside to SLT is that is doesn't work for everyone. We like to think of SLT as an adjunctive therapy to eye drops ... if you are taking a single glaucoma drop, SLT therapy may be able to get you off it. If you are already on glaucoma drops and your eye pressure is creeping up, an SLT treatment may keep you from needing an additional drop or surgery. The procedure takes about 5 minutes and is painless with little recovery time.
Snellen chart. This is the eye chart used by American eye doctors for measuring vision. The letters on this eye chart are calibrated based on distance measurements, comparing your vision to someone with "perfect" eyes. For example, if you have a vision of 20/60 ... this means that the letters you can barely see when standing 20 feet from the chart can be easily seen by a "perfect-eyed person" standing a full 60 feet away from the same chart! In the USA and many European countries, legal driving vision is 20/50 and you are considered legally blind if your corrected vision is 20/200 or worse. The Snellen chart is calibrated to be 20 feet from the exam chair you are sitting in ... but few eye doctors have exam rooms this long. To offset this, mirrors are used to obtain the full 20-foot distance.
Soothe. This is a brand name rewetting drops from Bausch & Lomb. Competing brands are Systane, Blink, GenTeal, and Refresh.
squinting. Squinting of the eyes is common, and is commonly done in an attempt to see better. If the eye has refractive error (like nearsightedness or farsightedness) the images entering the eye do not focus well on the retina and look blurry. By squinting and looking through the eyelashes, you can actually see a little clearer. The eyelashes turn the eye into a pinhole camera, which improves depth of focus and improves vision. Squinting is not a good long-term vision solution (obviously), so glasses or contacts are prescribed to improve vision and decrease eye strain. See the entry on pinholes to understand this concept better.
steroid. Steroids are useful in ophthalmology for treating ocular inflammation. This is particularly useful after cataract surgery and with internal ocular inflammation such as uveitis. Steroids can also be useful for decreasing corneal scarring, such as after a trauma or infection. Care must be used with steroids, however, as they can exacerbate infections - viruses and bacteria love steroids as it "makes them strong." While short term topical steroids are relatively safe, long-term use may cause some problems. Some people are "steroid responders" and their eye pressure ends to go up while on topical eye drops. This pressure change usually takes a few weeks to kick in and goes away after a couple of weeks off the drops. Steroids are also associated with premature cataract formation, though this is more of an issue with oral steroids. Common steroids used by eye doctors are prednisolone acetate (Pred-Forte or Econopred), loteprednol (Lotemax and Alrex) and dexamethasone (usually found in combination drops like Tobradex).
strabismus. This is a descriptive term used by eye doctors to describe eyes that are in poor alignment with each other. For example, someone with strabismus may be cross-eyed, wall-eyed, or have an eye that drifts upwards. Some people have strabismus that occurs only when tired and others have a problems with double vision only with reading. There are many causes for strabismus, from congenital motor problems to cranial nerve palsies. Strabismus needs to be evaluated by an eye doctor for an appropriate workup. If the alignment problem persists, strabismus surgery is sometimes recommended. Prism glasses are another option, especially for long-standing strabismus in adults.
strabismus surgery. This is surgery to correct ocular misalignment (strabismus). Most strabismus surgery is performed on toddlers to correct alignment problems such as crossed-eyes. This surgery involves the weakening or strengthening of eye muscles by shortening them or changing their insertion points on the edge of the eye. While most ophthalmologists have trained in performing strabismus surgery, these days the procedure is mostly carried out by pediatric ophthalmologists who have more practice with this type of surgery. Many pediatric ophthalmologists perform adult strabismus surgery as well.
stye. A stye is an infection of one of the oil or sweat glands running along the eyelid. Styes are tender to the touch and may form an abscess or pus layer that is visible through the skin as a "white head." The treatment for a stye typically begins with warm compresses and gentle massage. While a "pimple" elsewhere on the body can usually be "popped" or "lanced" with little ill effect, I strongly discourage being too aggressive with the eyelid as the eyeball underneath is a sensitive structure and easily injured. Also, some doctors think that aggressive eyelid squeezing may actually spread infection to adjacent skin and make the stye worse. If warm compresses and gentle massage aren't working, the stye may require topical or oral antibiotics, and even lancing. A stye is a bit different than a chalazion, which is a blockage of the deeper meibomian glands that tends to be painless.
subconjunctival hemorrhage. This is an extremely red eye that occurs when a blood vessel on the surface of the eye ruptures. The white part of the eye (the sclera) is covered by a very thin layer of skin called the conjunctiva. You can see this skin when looking in a mirror, as red blood vessels course through it and look like "lines" on the eye. If one of these blood vessels bursts for some reason, such as after a cough or sneeze, blood will track underneath the conjunctiva and make the eye look extremely red. It only takes a few drops of blood to make the eye look bright red and this can look quite alarming in the mirror. A subconjunctival hemorrhage is almost always harmless, but warrants a check to make sure there is no bleeding inside the eye (a hyphema or vitreous hemorrhage) and to make sure the cornea isn't drying out.
sulfa allergy. Several medicines are sulfa based and can cause problems for people allergic to sulfa drugs. The main culprits are the carbonic anhydrase inhibitors used for glaucoma. Examples of these glaucoma drops include dorzolamide, Trusopt, Azopt, and Cosopt. Also, the water pill Diamox (acetazolamide) is sometimes used for treating advanced glaucoma, but is sulfa-based as well. Sulfacetamide is an antibiotic eye drop (also called Bleph-10) that can also cause sulfa problems, but I rarely prescribe this, given the plethora of good antibiotic alternatives.
sulfacetamide sodium 10%. Also known by the trade name Bleph-10, this is an antibiotic eye drop that has gone generic and can be found on the Walmart $4 list. This drug is sulfa-based and not good for those people with sulfa allergy.
Systane. This is a brand name rewetting drop made by Alcon. Competing brands include Soothe, Blink, GenTeal, and Refresh.
T
tamsulosin. This is the active ingredient in Flomax, the medication used to help with urinary flow in men with prostate enlargement. Our main concern with this drug is that it can cause floppy iris syndrome during cataract surgery. Floppy iris syndrome is when the iris undulates and moves during a cataract operation and is a potential cause for complications.
tear film. Your tear film is crucial for both good vision and ocular comfort. The tear film is actually composed of three different layers. The innermost layer is made of mucous that helps the tears "stick" to the eye. The middle layer is composed of an aqueous water layer. The surface layer is composed of lipid (oil) that keeps the tear film from evaporating too quickly. This oil is produced by the meibomian glands. For the health of the tear film, both the amount of tears AND the composition of the tear film is important. Rewetting drops usually replace only the middle aqueous layer, while warm compresses can improve the oil production from the meibomian glands. Restasis eye drops may increase the eye's production of tears in certain cases, while punctal plugs keep the tears from draining away too quickly. The tear film is where the majority of light focusing occurs. If this surface has any irregularity to it (from dry eye or excessive tearing) the vision will be severely affected.
tearing. The tear film serves many functions for the eye. Tears lubricate the eye and protect the eye from foreign bodies by washing them away. Tears also help vision by creating a smooth surface for the refraction of light. Too little tears can cause dry eye, where the eyes feel irritated and "tired." Too much and the fluid will collect along the lower eyelid, making the eyes feel weepy and the vision blurry. Tearing can be so bad that the tears overwhelm the nasolacrimal "drain" and roll down the cheek instead (epiphora). Most people with "weepy" eyes actually suffer from dry eye. Their basal tear production is too low, causing intermittent episodes of ocular irritation. When the eyes are irritated, reflexive tearing from the lacrimal gland turns on and floods the eye like a waterfall. This results in periodic episodes of dry eye followed by periods of intense watering. Sometimes, a regularly scheduled regimen of rewetting drops (artificial tears) can help even out this cycle.
temporal arteritis. This is an inflammatory syndrome involving the arteries of the head and neck that can cause serious vision loss. With this condition, the arteries around the head become inflamed. If enough inflammation occurs, an artery can close off and cause sudden neurologic changes. If this happens to the arteries running to the eye, this creates a sudden loss of vision. Symptoms of temporal arteritis include temple pain (especially when brushing hair), jaw claudication (pain when chewing food), unexpected weight loss, night sweats, and general feeling of malaise. Diagnosis is first made by looking for inflammatory markers in the blood (ESR and CRP levels), with a possible biopsy of the temporal artery if a more definitive diagnosis is needed. A biopsy is usually performed by a vascular surgeon only if we feel that the result will change the management of this diagnosis. Treatment is with steroids, usually taken for a prolonged course over many months (sometimes more than a year). Temporal arteritis is considered a disease in the "elderly" and rarely seen under the age of 65. Temporal arteritis is sometimes called "giant cell arteritis" and is related to a systemic condition called polymyalgia rheumatica where similar inflammation occurs throughout the entire body.
tetracaine. This is an anesthetic drop used to numb the eye during an eye exam or prior to surgery. Tetracaine works similar to the novacaine that a dentist uses, but can be applied as a simple eye drop. This drop (or a similar drop called proparacaine) is commonly used to anesthetize the cornea prior to checking eye pressure with applanation tonometry. This drop is also used immediately prior to cataract surgery and minor surgical procedures. Tetracaine stings a little going in and will make the eye feel strange for a few minutes. The numbing effect lasts about 10-20 minutes before it begins to wear off. It is important that you not rub your eye while it is numb ... you may be scratching your cornea and cause damage to yourself without realizing it. This drop is never prescribed for home use as repeated applications can actually be toxic to the ocular surface and will keep wounds and corneal abrasions from healing properly.
third nerve palsy. This a paralysis or "stroke" to the third cranial nerve. This nerve is involved with most muscles controlling eye movement. When the nerve is damaged, this causes the eye to turn down and outwards. The third nerve is also involved with controlling pupil size, so a palsy will often make the pupil dilate. Finally, the third nerve helps with eyelid elevation and so a palsy will often cause the eyelid to droop (ptosis). A new third nerve palsy is a potential emergency, especially if the pupil is involved, and usually prompts a trip to the hospital to look for aneurysms or mass lesions that might be pushing on the nerve.
thyroid eye disease. Thyroid dysfunction can cause a number of ocular problems. The most common is dry eye, as the hormonal changes can decrease tear production. Graves disease can stiffen the eye muscles located behind the eyeball and cause fibrous deposits that make the eye muscles swell and expand. This can actually make the eyes protrude forward in a condition called exophthalmos. Thyroid dysfunction can also cause the upper eyelid to retract which can give a person a surprised or wide-eyed appearance. Finally, thyroid muscle dysfunction can cause double vision (diplopia).
timolol. This is a common beta-blocker eye drop used for treating glaucoma. This drop is usually dosed twice a day. Timolol is an older drop that has been around for a long time, so it is readily available as an inexpensive generic. Punctal occlusion is sometimes recommended to minimize any systemic side effects of timolol (decreased blood pressure and breathing issues in asthmatics).
timolol GFS. This is a beta-blocker eye drop used for treating glaucoma. The GFS stands for gel forming solution. It is a thicker consistency that allows the drop to be dosed only once a day. An inexpensive generic version is also available, but is dosed twice a day. Timolol GFS is also available under the trade name Istalol.
Timoptic. This is the trade name for a eye drop containing timolol. This is a beta-blocker medication that lowers eye pressure by decreasing aqueous fluid production inside the eye. I never see this medicine in circulation, as generic timolol is inexpensive and easily obtained.
Tobradex. A popular eye drop used to limit infection and reduce inflammation of the eye. The drop is a combination drug containing two different medicines. Tobramycin is an antibiotic good for treating infections and decreasing bacterial load around the eyelids. Dexamethasone is a steroid used for decreasing inflammation. A competing eye drop with similar action is called Zylet. There is a generic available for Tobradex, but it isn't as cheap as one would expect. We will sometimes prescribe Maxitrol instead - it is very inexpensive, but a little harsh on the eye and not tolerated well by everyone (especially with prolonged use).
Tobradex ST. This is an eye drop used for treating infection and inflammation. It contains both an antibiotic (tobramycin) and a steroid (dexamethasone). This medicine is almost exactly the same as "regular Tobradex," except it is a thicker suspension and designed to work better than the older version.
tobramycin. This is an inexpensive antibiotic eye drop with good bacterial coverage. It is readily available and can be found in combination drops such as Tobradex.
tobramycin/dexamethasone. This is a combination drop containing tobramycin (an antibiotic) and dexamethasone (a steroid). Combination drops like this are especially good at treating ocular inflammation caused by blepharitis. In the eye world, we usually refer to this drop by the trade name Tobradex.
Tobrex. This is the trade name for the antibiotic eye drop tobramycin. As tobramycin is available as a very cheap generic, I rarely see "Tobrex" in circulation anymore.
tonometry. This is how we measure the pressure inside the eye. The internal eye pressure is extremely important for the health of the eye. If the pressure is too high, glaucoma damage will occur. If too low, the eye deflates like a water balloon and retinal distortions and macular edema can occur. There are many ways to check the eye pressure, such as the "air puff test," but the one used most often is called the Goldman Applanation Tonometry. This is a small plastic probe that is illuminated with a blue light. As the probe pushes on the eye it flattens a small area of the cornea. The amount of pressure required to flatten the cornea can be used to estimate the internal ocular pressure. This is a relatively accurate device, though corneal thickness can make the readings less so. This applanation tonometry is generally less aggravating then the air puff test. Another tonometry device is called the Tono-Pen. This is a handheld machine that looks like a pen. It is touched to the surface of the eye and works by a similar method. The Tono-Pen is not as accurate as other methods, but is sometimes the only way to accurately measure pressure in a person who is bedridden or who can't get their head into a microscope.
Tono-Pen. A small hand-held electronic machine that is sometimes used to check eye pressure. While not as accurate as other methods, the Tono-Pen is useful for the bedridden and people who can't get up to the microscope for more traditional pressure measurements. To use the Tono-Pen, the eye is numbed with anesthetic drops and the device is gently tapped against the front of the cornea. This doesn't hurt, but feels a little odd. Sterile rubber covers (they look like rubber balloons or miniature condoms) are applied to the Tono-Pen to keep the procedure completely sterile.
topography. In relation to the eye, topography usually refers to corneal topography - this is the measurement of the surface of the cornea. The cornea, the clear window that makes up the front of our eye, works like a fixed-focus lens and actually does the majority of the light focusing in our eye. Irregularities in the corneal surface can have dramatic impact on vision. Corneal topography can be used to measure and map out the corneal surface, similar to mapping out a mountain range in a topographical map. Aberrations like astigmatism can be detected, as can higher-order irregularities such as keratoconus.
toric contacts. These are contacts designed to help with astigmatism. Normally, the cornea (the clear window that makes up the front of our eye) is perfectly round like a basketball. However, in people with astigmatism, their eye is shaped more like a football ... that is to say, the cornea is steep along one axis and shallower along another. Everyone has a little bit of astigmatism - after all, we are not perfectly round creatures. However, some people have a significant amount of astigmatism and this irregularity can cause some blur to the vision. astigmatism is relatively easy to fix in glasses. The "football correction" can be ground into a pair of glasses to perfectly offset the eye's football shape. This same process is trickier to pull off with contacts. The football shape can be melted into a plastic contact lens, but contacts have a tendency to spin on the surface of the eye. To counter this, toric contacts are weighted with a thicker bottom so that they line up properly. While this works well, there is no doubt that toric contacts are trickier to fit than a regular contact lens prescription.
toric implants. These are implants used in cataract surgery designed to counteract the eye's natural astigmatism. Astigmatism is the condition where the eye isn't round, but has an oval shape similar to the side of a football. This is relatively easy to correct with glasses, as the mirror image of the "football" can be ground into a pair of spectacles and rotated in the glasses frame until the vision is perfected. Astigmatism can now be corrected during cataract surgery using a "toric implant" that has this football correction built in. During cataract surgery, the new toric implant is inserted to replace the old cloudy cataract. The toric implant is then spun until its "football" is lined up to offset the eye's natural astigmatism. While there is no guarantee that a toric lens will keep someone completely "glasses free" after surgery, these implants significantly decrease astigmatism and lessen your dependence on glasses afterward.
Tozal. This is a prescription vitamin used to treat macular degeneration and dry eye. It contains most of the vitamins from the AREDS Study, along with the Omega-3 fatty acids and plant pigments (lutein and zeaxanthin) from the AREDS 2 Study. Tozal also contains taurine, a protein that is commonly found in energy drinks that is "supposed" to increase energy production in the retina. I rarely prescribe this medicine, as good AREDS vitamins (Ocuvite, PreserVision, I-CAPS) are available over the counter without a prescription. I will use it on occasion if your prescription drug coverage is excellent, or I am worried about your getting the proper eye vitamins (such as someone in a nursing home who can't reliably get non-prescription medications).
trabecular meshwork. This is the drain inside the eye where excess aqueous fluid drains and returns back to the bloodstream. This drain is located in a 360-degree ring inside the eye, right where the sclera (the white of the eye) meets the iris (the colored part of the eye). The trabecular meshwork is difficult to see directly, even when using the eye microscope because it is located inside the eye and "around the corner" in the angle of the eye. To help with visualization, a special mirrored-lens can be placed on the surface of the eye. This technique is called gonioscopy and is painless. It is believed that people with chronic open angle glaucoma have something microscopic clogging up the meshwork (like a dirty coffee filter). Other people have narrow angles, such that their drainage angle is tight so that fluid has a hard time reaching the trabecular meshwork to begin with. If this narrow drainage angle closes off entirely, fluid can't drain out of the eye and the ocular pressure shoots up very high. This process is called acute glaucoma, and a person's risk for having a glaucoma attack can be estimated by examining the trabecular meshwork during gonioscopy.
trabeculectomy. This is a glaucoma surgery, commonly performed to reduce pressure in the eye. Glaucoma occurs because the pressure in the eye is too high. The exact cause for this pressure elevation is unclear, though some people believe that something microscopic is clogging the drain (trabecular meshwork) inside the eye such that aqueous fluid has a hard time leaving the eye. With a trabeculectomy surgery, a new drainage pathway is created so that aqueous fluid from the anterior chamber drains directly to a "pocket" under the conjunctiva skin. This pocket (also called a "bleb") looks like a small blister on the white of the eye under the upper eyelid. Here the aqueous fluid is eventually reabsorbed back into the body. Trabeculectomy is the most common glaucoma surgery performed (more common than tube-shunt surgery). While it is successful at lowering pressure, it does run some long-term risk such as increased chance of internal ocular infection if the bleb ever breaks down. While most ophthalmologists are trained to perform this surgery, we usually leave advanced glaucoma surgeries to glaucoma specialists.
trabeculoplasty. This is a glaucoma laser procedure used to improve the flow of aqueous fluid out of the eye. A laser is applied to the trabecular meshwork, which acts as a filter for the fluid leaving the eye. There are two different types of laser therapy used. ALT is a "hot laser" that creates scar spots in the trabecular meshwork that physically open the meshwork to allow drainage. While effective, ALT can only be done once as the eye can only tolerate so much scaring. SLT is a newer laser technology. It is often described as a "cold laser" because it doesn't create the same scaring and can be repeated if necessary.
Travatan. This is a popular glaucoma eye drop medicine. This is a prostaglandin drop and used once daily, usually at bedtime. Competing brands in the same drug class include Lumigan and generic Xalatan (latanoprost).
Travatan Z. This is a glaucoma drop used to lower eye pressure. It is actually the same medicine as regular Travatan (travoprost). However, the manufacturer changed the preservative from BAK to a gentler preservative in an attempt to make the drop less harsh on the corneal surface. Like all prostaglandin glaucoma drops, it is dosed once a day (usually at bedtime).
travoprost. A glaucoma eye drop medication. This is the active ingredient in the eye drops Travatan and Travatan Z. This prostaglandin medication is similar to latanoprost (Xalatan) and thus only needs to be taken once a day.
transitional lenses. These are lenses in glasses that darken when exposed to sunlight. While very effective, they can sometimes take a little while to clear again after you walk inside. Also, transitionals require UV light to change color. Since car windows block UV light (explaining why you don't get sunburned in the car) transitional glasses don't work as well for driving.
triamcinolone. More commonly known as Kenalog, this is a injection steroid used in and around the eye. Retina specialists may inject this medicine into the eye to decrease retinal swelling (macular edema) or to reduce ocular inflammation with recalcitrant uveitis. I occasionally inject this medicine into eyelid lesions, such as chalazions, in order to minimize inflammation and speed up recovery.
trichiasis. This is when eyelashes grow in the wrong direction, rubbing on the surface of the eye and causing irritation. While common, trichiasis is difficult to treat as lashes are thick and the lash follicle hard to destroy. Epilation (plucking) of the eyelashes can be done in the doctors office, though some people with good sight and steady hands are able to pull this off at home with blunt tweezers. If persistent, more aggressive surgical correction can be considered.
trifluridine. Also known by the trade name Viroptic, this is an antiviral drop used primarily to fight herpetic eye disease.
trifocal. These are glasses with three separate zones of focus. The top is set for distance, the middle for intermediate (such as computer distance) while the bottom is optimized for reading. While effective, many people don't like having this many lines on their glasses. For these people, a progressive lens (no line bifocal) may work. Purchasing separate computer glasses may be another option.
tropicamide. This is a dilating drop using during your eye exam. This drop is used in conjunction with phenylephrine to make the pupil dilate to aid in visualizing the lens and retina. Tropicamide is also a short-acting cycloplegia medicine and will make the vision blurry for a couple of hours. This drop is rarely prescribed outside the office, however, as longer acting cycloplegics like atropine and cyclopentolate are more effective in treating eye pain and inflammation. Like all dilating
drops, the bottle has a red-colored cap.
Trusopt. Also known as dorzolamide, this is a glaucoma eye drop. This is a carbonic anhydrase inhibitor, which is effective but may be problematic if you have a sulfa allergy. Other medicines in this class of drugs include Azopt (brinzolamide) and the oral medication Diamox. This medicine is also available as the combination drug Cosopt (containing both dorzolamide and timolol).
tube-shunt. This is a surgical procedure performed for severe cases of glaucoma. With glaucoma, the eye pressure is high, which causes gradual death of the optic nerve. There are many ways to lower the eye pressure. Many doctors begin with medicated eye drops. These work to improve the outflow of aqueous fluid from the eye. Other drops decrease the production of aqueous fluid. Laser therapy (such as SLT) can also be performed to improve fluid outflow. If these methods aren't working and visual loss is eminent, a glaucoma surgery can be considered. With a tube-shunt, a small plastic tube is inserted into the anterior chamber in the front of the eye. This tube drains or "shunts" excess aqueous fluid to a pocket under the conjunctiva skin of the eye, up under the eyelid. From here, the vitreous fluid percolates back into the body and is absorbed into the blood stream. This drainage pathway is entirely covered by the conjunctiva skin, so there is no drainage to the outside world. This is important as we don't want to give environmental bacteria an entrance into the eye. Tube-shunt procedures are much more difficult and time consuming than most eye surgeries so are usually reserved for people with advanced or intractable glaucoma.
twitching eyelid. A twitch or jumping eyelid that tends to come in waves. See eyelid fasciculation for more information.
tear film. Your tear film is crucial for both good vision and ocular comfort. The tear film is actually composed of three different layers. The innermost layer is made of mucous that helps the tears "stick" to the eye. The middle layer is composed of an aqueous water layer. The surface layer is composed of lipid (oil) that keeps the tear film from evaporating too quickly. This oil is produced by the meibomian glands. For the health of the tear film, both the amount of tears AND the composition of the tear film is important. Rewetting drops usually replace only the middle aqueous layer, while warm compresses can improve the oil production from the meibomian glands. Restasis eye drops may increase the eye's production of tears in certain cases, while punctal plugs keep the tears from draining away too quickly. The tear film is where the majority of light focusing occurs. If this surface has any irregularity to it (from dry eye or excessive tearing) the vision will be severely affected.
tearing. The tear film serves many functions for the eye. Tears lubricate the eye and protect the eye from foreign bodies by washing them away. Tears also help vision by creating a smooth surface for the refraction of light. Too little tears can cause dry eye, where the eyes feel irritated and "tired." Too much and the fluid will collect along the lower eyelid, making the eyes feel weepy and the vision blurry. Tearing can be so bad that the tears overwhelm the nasolacrimal "drain" and roll down the cheek instead (epiphora). Most people with "weepy" eyes actually suffer from dry eye. Their basal tear production is too low, causing intermittent episodes of ocular irritation. When the eyes are irritated, reflexive tearing from the lacrimal gland turns on and floods the eye like a waterfall. This results in periodic episodes of dry eye followed by periods of intense watering. Sometimes, a regularly scheduled regimen of rewetting drops (artificial tears) can help even out this cycle.
temporal arteritis. This is an inflammatory syndrome involving the arteries of the head and neck that can cause serious vision loss. With this condition, the arteries around the head become inflamed. If enough inflammation occurs, an artery can close off and cause sudden neurologic changes. If this happens to the arteries running to the eye, this creates a sudden loss of vision. Symptoms of temporal arteritis include temple pain (especially when brushing hair), jaw claudication (pain when chewing food), unexpected weight loss, night sweats, and general feeling of malaise. Diagnosis is first made by looking for inflammatory markers in the blood (ESR and CRP levels), with a possible biopsy of the temporal artery if a more definitive diagnosis is needed. A biopsy is usually performed by a vascular surgeon only if we feel that the result will change the management of this diagnosis. Treatment is with steroids, usually taken for a prolonged course over many months (sometimes more than a year). Temporal arteritis is considered a disease in the "elderly" and rarely seen under the age of 65. Temporal arteritis is sometimes called "giant cell arteritis" and is related to a systemic condition called polymyalgia rheumatica where similar inflammation occurs throughout the entire body.
tetracaine. This is an anesthetic drop used to numb the eye during an eye exam or prior to surgery. Tetracaine works similar to the novacaine that a dentist uses, but can be applied as a simple eye drop. This drop (or a similar drop called proparacaine) is commonly used to anesthetize the cornea prior to checking eye pressure with applanation tonometry. This drop is also used immediately prior to cataract surgery and minor surgical procedures. Tetracaine stings a little going in and will make the eye feel strange for a few minutes. The numbing effect lasts about 10-20 minutes before it begins to wear off. It is important that you not rub your eye while it is numb ... you may be scratching your cornea and cause damage to yourself without realizing it. This drop is never prescribed for home use as repeated applications can actually be toxic to the ocular surface and will keep wounds and corneal abrasions from healing properly.
third nerve palsy. This a paralysis or "stroke" to the third cranial nerve. This nerve is involved with most muscles controlling eye movement. When the nerve is damaged, this causes the eye to turn down and outwards. The third nerve is also involved with controlling pupil size, so a palsy will often make the pupil dilate. Finally, the third nerve helps with eyelid elevation and so a palsy will often cause the eyelid to droop (ptosis). A new third nerve palsy is a potential emergency, especially if the pupil is involved, and usually prompts a trip to the hospital to look for aneurysms or mass lesions that might be pushing on the nerve.
thyroid eye disease. Thyroid dysfunction can cause a number of ocular problems. The most common is dry eye, as the hormonal changes can decrease tear production. Graves disease can stiffen the eye muscles located behind the eyeball and cause fibrous deposits that make the eye muscles swell and expand. This can actually make the eyes protrude forward in a condition called exophthalmos. Thyroid dysfunction can also cause the upper eyelid to retract which can give a person a surprised or wide-eyed appearance. Finally, thyroid muscle dysfunction can cause double vision (diplopia).
timolol. This is a common beta-blocker eye drop used for treating glaucoma. This drop is usually dosed twice a day. Timolol is an older drop that has been around for a long time, so it is readily available as an inexpensive generic. Punctal occlusion is sometimes recommended to minimize any systemic side effects of timolol (decreased blood pressure and breathing issues in asthmatics).
timolol GFS. This is a beta-blocker eye drop used for treating glaucoma. The GFS stands for gel forming solution. It is a thicker consistency that allows the drop to be dosed only once a day. An inexpensive generic version is also available, but is dosed twice a day. Timolol GFS is also available under the trade name Istalol.
Timoptic. This is the trade name for a eye drop containing timolol. This is a beta-blocker medication that lowers eye pressure by decreasing aqueous fluid production inside the eye. I never see this medicine in circulation, as generic timolol is inexpensive and easily obtained.
Tobradex. A popular eye drop used to limit infection and reduce inflammation of the eye. The drop is a combination drug containing two different medicines. Tobramycin is an antibiotic good for treating infections and decreasing bacterial load around the eyelids. Dexamethasone is a steroid used for decreasing inflammation. A competing eye drop with similar action is called Zylet. There is a generic available for Tobradex, but it isn't as cheap as one would expect. We will sometimes prescribe Maxitrol instead - it is very inexpensive, but a little harsh on the eye and not tolerated well by everyone (especially with prolonged use).
Tobradex ST. This is an eye drop used for treating infection and inflammation. It contains both an antibiotic (tobramycin) and a steroid (dexamethasone). This medicine is almost exactly the same as "regular Tobradex," except it is a thicker suspension and designed to work better than the older version.
tobramycin. This is an inexpensive antibiotic eye drop with good bacterial coverage. It is readily available and can be found in combination drops such as Tobradex.
tobramycin/dexamethasone. This is a combination drop containing tobramycin (an antibiotic) and dexamethasone (a steroid). Combination drops like this are especially good at treating ocular inflammation caused by blepharitis. In the eye world, we usually refer to this drop by the trade name Tobradex.
Tobrex. This is the trade name for the antibiotic eye drop tobramycin. As tobramycin is available as a very cheap generic, I rarely see "Tobrex" in circulation anymore.
tonometry. This is how we measure the pressure inside the eye. The internal eye pressure is extremely important for the health of the eye. If the pressure is too high, glaucoma damage will occur. If too low, the eye deflates like a water balloon and retinal distortions and macular edema can occur. There are many ways to check the eye pressure, such as the "air puff test," but the one used most often is called the Goldman Applanation Tonometry. This is a small plastic probe that is illuminated with a blue light. As the probe pushes on the eye it flattens a small area of the cornea. The amount of pressure required to flatten the cornea can be used to estimate the internal ocular pressure. This is a relatively accurate device, though corneal thickness can make the readings less so. This applanation tonometry is generally less aggravating then the air puff test. Another tonometry device is called the Tono-Pen. This is a handheld machine that looks like a pen. It is touched to the surface of the eye and works by a similar method. The Tono-Pen is not as accurate as other methods, but is sometimes the only way to accurately measure pressure in a person who is bedridden or who can't get their head into a microscope.
Tono-Pen. A small hand-held electronic machine that is sometimes used to check eye pressure. While not as accurate as other methods, the Tono-Pen is useful for the bedridden and people who can't get up to the microscope for more traditional pressure measurements. To use the Tono-Pen, the eye is numbed with anesthetic drops and the device is gently tapped against the front of the cornea. This doesn't hurt, but feels a little odd. Sterile rubber covers (they look like rubber balloons or miniature condoms) are applied to the Tono-Pen to keep the procedure completely sterile.
topography. In relation to the eye, topography usually refers to corneal topography - this is the measurement of the surface of the cornea. The cornea, the clear window that makes up the front of our eye, works like a fixed-focus lens and actually does the majority of the light focusing in our eye. Irregularities in the corneal surface can have dramatic impact on vision. Corneal topography can be used to measure and map out the corneal surface, similar to mapping out a mountain range in a topographical map. Aberrations like astigmatism can be detected, as can higher-order irregularities such as keratoconus.
toric contacts. These are contacts designed to help with astigmatism. Normally, the cornea (the clear window that makes up the front of our eye) is perfectly round like a basketball. However, in people with astigmatism, their eye is shaped more like a football ... that is to say, the cornea is steep along one axis and shallower along another. Everyone has a little bit of astigmatism - after all, we are not perfectly round creatures. However, some people have a significant amount of astigmatism and this irregularity can cause some blur to the vision. astigmatism is relatively easy to fix in glasses. The "football correction" can be ground into a pair of glasses to perfectly offset the eye's football shape. This same process is trickier to pull off with contacts. The football shape can be melted into a plastic contact lens, but contacts have a tendency to spin on the surface of the eye. To counter this, toric contacts are weighted with a thicker bottom so that they line up properly. While this works well, there is no doubt that toric contacts are trickier to fit than a regular contact lens prescription.
toric implants. These are implants used in cataract surgery designed to counteract the eye's natural astigmatism. Astigmatism is the condition where the eye isn't round, but has an oval shape similar to the side of a football. This is relatively easy to correct with glasses, as the mirror image of the "football" can be ground into a pair of spectacles and rotated in the glasses frame until the vision is perfected. Astigmatism can now be corrected during cataract surgery using a "toric implant" that has this football correction built in. During cataract surgery, the new toric implant is inserted to replace the old cloudy cataract. The toric implant is then spun until its "football" is lined up to offset the eye's natural astigmatism. While there is no guarantee that a toric lens will keep someone completely "glasses free" after surgery, these implants significantly decrease astigmatism and lessen your dependence on glasses afterward.
Tozal. This is a prescription vitamin used to treat macular degeneration and dry eye. It contains most of the vitamins from the AREDS Study, along with the Omega-3 fatty acids and plant pigments (lutein and zeaxanthin) from the AREDS 2 Study. Tozal also contains taurine, a protein that is commonly found in energy drinks that is "supposed" to increase energy production in the retina. I rarely prescribe this medicine, as good AREDS vitamins (Ocuvite, PreserVision, I-CAPS) are available over the counter without a prescription. I will use it on occasion if your prescription drug coverage is excellent, or I am worried about your getting the proper eye vitamins (such as someone in a nursing home who can't reliably get non-prescription medications).
trabecular meshwork. This is the drain inside the eye where excess aqueous fluid drains and returns back to the bloodstream. This drain is located in a 360-degree ring inside the eye, right where the sclera (the white of the eye) meets the iris (the colored part of the eye). The trabecular meshwork is difficult to see directly, even when using the eye microscope because it is located inside the eye and "around the corner" in the angle of the eye. To help with visualization, a special mirrored-lens can be placed on the surface of the eye. This technique is called gonioscopy and is painless. It is believed that people with chronic open angle glaucoma have something microscopic clogging up the meshwork (like a dirty coffee filter). Other people have narrow angles, such that their drainage angle is tight so that fluid has a hard time reaching the trabecular meshwork to begin with. If this narrow drainage angle closes off entirely, fluid can't drain out of the eye and the ocular pressure shoots up very high. This process is called acute glaucoma, and a person's risk for having a glaucoma attack can be estimated by examining the trabecular meshwork during gonioscopy.
trabeculectomy. This is a glaucoma surgery, commonly performed to reduce pressure in the eye. Glaucoma occurs because the pressure in the eye is too high. The exact cause for this pressure elevation is unclear, though some people believe that something microscopic is clogging the drain (trabecular meshwork) inside the eye such that aqueous fluid has a hard time leaving the eye. With a trabeculectomy surgery, a new drainage pathway is created so that aqueous fluid from the anterior chamber drains directly to a "pocket" under the conjunctiva skin. This pocket (also called a "bleb") looks like a small blister on the white of the eye under the upper eyelid. Here the aqueous fluid is eventually reabsorbed back into the body. Trabeculectomy is the most common glaucoma surgery performed (more common than tube-shunt surgery). While it is successful at lowering pressure, it does run some long-term risk such as increased chance of internal ocular infection if the bleb ever breaks down. While most ophthalmologists are trained to perform this surgery, we usually leave advanced glaucoma surgeries to glaucoma specialists.
trabeculoplasty. This is a glaucoma laser procedure used to improve the flow of aqueous fluid out of the eye. A laser is applied to the trabecular meshwork, which acts as a filter for the fluid leaving the eye. There are two different types of laser therapy used. ALT is a "hot laser" that creates scar spots in the trabecular meshwork that physically open the meshwork to allow drainage. While effective, ALT can only be done once as the eye can only tolerate so much scaring. SLT is a newer laser technology. It is often described as a "cold laser" because it doesn't create the same scaring and can be repeated if necessary.
Travatan. This is a popular glaucoma eye drop medicine. This is a prostaglandin drop and used once daily, usually at bedtime. Competing brands in the same drug class include Lumigan and generic Xalatan (latanoprost).
Travatan Z. This is a glaucoma drop used to lower eye pressure. It is actually the same medicine as regular Travatan (travoprost). However, the manufacturer changed the preservative from BAK to a gentler preservative in an attempt to make the drop less harsh on the corneal surface. Like all prostaglandin glaucoma drops, it is dosed once a day (usually at bedtime).
travoprost. A glaucoma eye drop medication. This is the active ingredient in the eye drops Travatan and Travatan Z. This prostaglandin medication is similar to latanoprost (Xalatan) and thus only needs to be taken once a day.
transitional lenses. These are lenses in glasses that darken when exposed to sunlight. While very effective, they can sometimes take a little while to clear again after you walk inside. Also, transitionals require UV light to change color. Since car windows block UV light (explaining why you don't get sunburned in the car) transitional glasses don't work as well for driving.
triamcinolone. More commonly known as Kenalog, this is a injection steroid used in and around the eye. Retina specialists may inject this medicine into the eye to decrease retinal swelling (macular edema) or to reduce ocular inflammation with recalcitrant uveitis. I occasionally inject this medicine into eyelid lesions, such as chalazions, in order to minimize inflammation and speed up recovery.
trichiasis. This is when eyelashes grow in the wrong direction, rubbing on the surface of the eye and causing irritation. While common, trichiasis is difficult to treat as lashes are thick and the lash follicle hard to destroy. Epilation (plucking) of the eyelashes can be done in the doctors office, though some people with good sight and steady hands are able to pull this off at home with blunt tweezers. If persistent, more aggressive surgical correction can be considered.
trifluridine. Also known by the trade name Viroptic, this is an antiviral drop used primarily to fight herpetic eye disease.
trifocal. These are glasses with three separate zones of focus. The top is set for distance, the middle for intermediate (such as computer distance) while the bottom is optimized for reading. While effective, many people don't like having this many lines on their glasses. For these people, a progressive lens (no line bifocal) may work. Purchasing separate computer glasses may be another option.
tropicamide. This is a dilating drop using during your eye exam. This drop is used in conjunction with phenylephrine to make the pupil dilate to aid in visualizing the lens and retina. Tropicamide is also a short-acting cycloplegia medicine and will make the vision blurry for a couple of hours. This drop is rarely prescribed outside the office, however, as longer acting cycloplegics like atropine and cyclopentolate are more effective in treating eye pain and inflammation. Like all dilating
drops, the bottle has a red-colored cap.
Trusopt. Also known as dorzolamide, this is a glaucoma eye drop. This is a carbonic anhydrase inhibitor, which is effective but may be problematic if you have a sulfa allergy. Other medicines in this class of drugs include Azopt (brinzolamide) and the oral medication Diamox. This medicine is also available as the combination drug Cosopt (containing both dorzolamide and timolol).
tube-shunt. This is a surgical procedure performed for severe cases of glaucoma. With glaucoma, the eye pressure is high, which causes gradual death of the optic nerve. There are many ways to lower the eye pressure. Many doctors begin with medicated eye drops. These work to improve the outflow of aqueous fluid from the eye. Other drops decrease the production of aqueous fluid. Laser therapy (such as SLT) can also be performed to improve fluid outflow. If these methods aren't working and visual loss is eminent, a glaucoma surgery can be considered. With a tube-shunt, a small plastic tube is inserted into the anterior chamber in the front of the eye. This tube drains or "shunts" excess aqueous fluid to a pocket under the conjunctiva skin of the eye, up under the eyelid. From here, the vitreous fluid percolates back into the body and is absorbed into the blood stream. This drainage pathway is entirely covered by the conjunctiva skin, so there is no drainage to the outside world. This is important as we don't want to give environmental bacteria an entrance into the eye. Tube-shunt procedures are much more difficult and time consuming than most eye surgeries so are usually reserved for people with advanced or intractable glaucoma.
twitching eyelid. A twitch or jumping eyelid that tends to come in waves. See eyelid fasciculation for more information.