Eye Dictionary: G
G
ganciclovir. This is a powerful antiviral medication that is now available as an eye ointment called Zirgan. We use this medicine in our practice to treat herpetic eye disease. Retina specialists occasionally use ganciclovir to treat viral infections (usually related to HIV) in the retina.
Garamycin. A trade name for the medication gentamicin. This is an antibiotic and is available as an ointment or eye drop. The generic equivalent is very cheap.
gatifloxacin. This is a powerful fluoroquinolone antibiotic eye drop, often used with more serious infections (such as contact lens related corneal ulcers) and after cataract surgery. The trade name for gatifloxacin is Zymaxid. Similar medicines in the same class include moxifloxacin (Vigamox & Moxeza) and besifloxacin (Besivance).
gentamicin. This is an older antibiotic eye drop that is also available as an ophthalmic ointment. This medicine has gone generic and is inexpensive, so I see it prescribed by many emergency rooms and urgent care clinics. While fairly effective, this medicine can be a little irritating to the eye with prolonged use. Alternative medicines like tobramycin drops or erythromycin ointment are also inexpensive and seem to be better tolerated.
GenTeal. A popular brand of over-the-counter rewetting drops. Genteal also makes a nighttime rewetting ointment called "GenTeal Gel" that is useful for extreme dry eyes. Competing brands include Refresh and Systane.
ghost image. This is when you see double, but the second image is less bright and usually offset to the side of the main object you are staring at. Ghost images are usually secondary to visual opacities such as a cataract or astigmatism. Upon further questioning, most people with monocular diplopia (double vision from a single eye) are often experiencing a ghost image or shadow rather than a true doubling of their vision.
glare. This is when you see halos or blur when exposed to bright lights. Many people with dense cataracts complain of glare while driving at night ... the headlights from oncoming traffic make it hard to see. Glare is usually associated with cataracts and one of the indicators that it may be time for cataract surgery. Another cause of glare is corneal swelling from diseases like Fuchs' dystrophy. Some people have sensitive eyes and seem to suffer from glare without any obvious anatomic abnormalities. Sunglasses during the day may help. At night, a glareresistant coating on glasses may help.
glasses. These are focusing lenses used to improve vision. There are many options when buying a modern set of glasses. For example, you can have them made with bifocals, trifocals, or even a no-line bifocal called a progressive lens. Glasses are also available as transitional lenses that darken when exposed to sunlight.
glasses prescription. A glasses prescription is the little piece of paper that has your spectacle correction written on it. There are many numbers on a glasses prescription and they can be a little daunting to decode if you've never done this before. The first number is your basic refractive error: if you are farsighted this will be a positive number and if nearsighted this will be a negative number. The second number is how much astigmatism you have (if you have any). The last number is a degree measurement used to align the astigmatism glasses in their frames properly. Finally, the "add" is the power of any bifocal correction and can range anywhere from +1.00 to +3.50 depending upon your age and how close to your face you like to read books. OD stands for right eye and OS is the left eye.
glaucoma. Glaucoma is best described as high pressure in the eye that causes damage to the optic nerve. The optic nerve is the large nerve that sends visual information from the eye to the brain. High pressure causes damage to this nerve over time. Glaucoma is a very slow process that usually has no real symptoms other than peripheral vision loss that may go unnoticed until far advanced. Diagnosis is made by measuring the eye pressure, examining various risk factors such as family history and corneal thickness, and by measuring actual damage with optic nerve scans (such as OCT) and visual field testing. Treatment is focused on lowering eye pressure with topical eye drops, laser therapy (SLT), and even surgical treatment (trabeculoplasty or tube-shunt). Most people have chronic open-angle glaucoma and develop visual problems slowly over time. A minority suffer from acute glaucoma and develop acute pain, blurry vision, and extremely high eye pressure. If glaucoma goes unchecked, it will lead to permanent vision loss and even blindness.
OD: - 2.00 + 1.00 x 180 deg
OS: - 1.50 + 0.75 x 020 deg
Bifocal Add: +3.00
glaucoma suspect. This is a person who "might" have glaucoma. The diagnosis of glaucoma is not always an obvious one. There is no "one test" that says if a person has glaucoma. Instead, we look at various risk factors to decide if you look "suspicious enough" to have glaucoma. The most obvious risk factor is high eye pressure. If your pressure is "through the roof" ... then sure, you probably have glaucoma. The difficulty here is that "normal" eye pressure is different for everyone.
Normal pressure ranges from 10 to 21. However, some people have pressures of 25 (or higher) and never develop glaucoma damage. Other people have pressures of 15 and yet are exquisitely sensitive to minor pressure elevations (this condition is referred to as low-tension glaucoma). Other risk factors we look at are family history and circulation problems like migraine headaches. A thin cornea, as measured by pachymetry, has been found to be an independent risk factor for glaucoma, though we don't know why. As glaucoma progresses, damage occurs at the optic nerve in the back of the eye and the optic disk begins to look hollowed out. This is called glaucomatous cupping. Your eye doctor can examine your nerves with a dilated eye exam and look for this appearance, but once again, some people have "suspicious looking nerves," but don't actually have true glaucoma. Finally, we can check for actual vision loss by performing a visual field. Glaucoma damage produces characteristic patterns of vision loss in your peripheral vision. Periodic eye exams are necessary to monitor for pressure fluctuations, photograph optic nerve appearance, and to detect visual field problems. This is all in an attempt to detect early glaucoma so that therapy can start, if needed.
glaucomatous cupping. This is a descriptive term for the changes that occur at the optic nerve from glaucoma damage. The optic nerve is the big nerve that connects the eyeball to the brain. It is located at the back of the eye, and its insertion can be seen inside the eye in the retina. This nerve is like a tube or pipe, with over a million individual nerve cell "wires" running through it ... kind of like a bundle of wires running through a PVC pipe. With glaucoma, the nerve fibers die off one by one and eventually disappear. With time, this creates a hollowed out appearance to the optic nerve which can be seen during an exam. This hollowed out appearance looks like the inside of a bowl or "cup" and is called glaucomatous cupping. People with advanced glaucoma have significant cupping with hollowed out optic nerves. Some people have the appearance of glaucomatous cupping, but in reality have perfectly normal eyes. This is because some people are born with larger optic nerves ... their "pipe" is very large with a lot of excess room inside of it that gives the illusion of nerve loss, but in reality they are perfectly healthy. This anatomical variety is one of the reasons eye doctors take photos and scans of the optic nerve - to see if "cupping" has gotten worse over time.
gonioscopy. This is the eye exam technique used to examine the drainage angle inside the eye, and is used to evaluate for glaucoma. The front part of the eye is filled with a fluid called the aqueous humor. This fluid nourishes many structures inside the eye and the balance of aqueous production and drainage is what controls the overall pressure of the eye. The aqueous "drain" is called the trabecular meshwork and is located in a 360-degree ring ... right at the point where the iris (the colored part of the eye) intersects with the sclera (the white of the eye). This drainage intersection is also known as the "angle" because of the insertion anatomy. Some people are at risk for their angle to narrow and close, leading to complete blockage of the drain which causes an acute glaucoma. It is useful for an eye doctor to examine this angle in order to let their patients know their risk for having one of these glaucoma attacks. Unfortunately, the angle is a little difficult to see, even with a microscope, because of its interior location. Gonioscopy is the technique where a special lens containing mirrors (a goniolens) is placed onto the surface of the eye. The doctor then looks through this lens/mirror device to see how "open" the angle appears. If the angle seems very tight, the risk of an acute glaucoma attack is high, and a prophylactic LPI laser procedure can be performed to decrease this risk.
GPC. This stands for Giant Papillary Conjunctivitis and is sometimes called "contact lens overwear syndrome." Contacts are made of plastic, but at a microscopic level they look like a sponge full of water. Just like a sponge, contacts tend to suck up irritants from the environment. Contacts also block the amount of oxygen the cornea normally absorbs from the air around us. This combination of irritants can aggravate the ocular surface and create a temporary inflammatory reaction. The eye becomes irritated and intolerant to contact lens wear. On exam, the eye looks red and may even have focal spots of inflammation on the cornea itself. When the eyelids are flipped over, giant papillary "bumps" can be seen - they look similar to allergic hives that you get on the skin. GPC tends to occur more in people who wear their contacts for extended periods or who sleep in their contacts, though sometimes we see this in people who are very conscientious with their ocular hygiene. Treatment usually involves a contact lens "holiday" to let the eyes recover. Rewetting drops, allergy drops, and occasionally a mild steroid can speed the healing process. Hopefully, after a few weeks of rest, contacts can slowly be resumed.
Graves' disease. Graves' disease is an autoimmune disorder where the thyroid pumps out too much thyroid hormone. Graves' is the most common cause for hyperthyroidism and is more common with women. Graves' can cause ocular problems such as eyelid retraction (giving people a wide-eyed appearance) and swelling of the eye muscles located behind the eye. This swelling causes the eye to protrude forward – a condition called proptosis or exophthalmos. Protrusion can cause extreme dry eye and exposure problems if the eyelids don't close completely while sleeping. Double vision is common secondary to the eye muscle involvement. If bad enough, muscle swelling can push on the optic nerve behind the eye and create neurologic vision loss. Treatment is geared toward normalizing thyroid levels and lubricating the eye. If double vision is constant, strabismus surgery can be considered. Decompression surgery (usually with an ENT doctor or an oculoplastic surgeon) is sometimes performed to give the eye more room inside the eye socket.
Garamycin. A trade name for the medication gentamicin. This is an antibiotic and is available as an ointment or eye drop. The generic equivalent is very cheap.
gatifloxacin. This is a powerful fluoroquinolone antibiotic eye drop, often used with more serious infections (such as contact lens related corneal ulcers) and after cataract surgery. The trade name for gatifloxacin is Zymaxid. Similar medicines in the same class include moxifloxacin (Vigamox & Moxeza) and besifloxacin (Besivance).
gentamicin. This is an older antibiotic eye drop that is also available as an ophthalmic ointment. This medicine has gone generic and is inexpensive, so I see it prescribed by many emergency rooms and urgent care clinics. While fairly effective, this medicine can be a little irritating to the eye with prolonged use. Alternative medicines like tobramycin drops or erythromycin ointment are also inexpensive and seem to be better tolerated.
GenTeal. A popular brand of over-the-counter rewetting drops. Genteal also makes a nighttime rewetting ointment called "GenTeal Gel" that is useful for extreme dry eyes. Competing brands include Refresh and Systane.
ghost image. This is when you see double, but the second image is less bright and usually offset to the side of the main object you are staring at. Ghost images are usually secondary to visual opacities such as a cataract or astigmatism. Upon further questioning, most people with monocular diplopia (double vision from a single eye) are often experiencing a ghost image or shadow rather than a true doubling of their vision.
glare. This is when you see halos or blur when exposed to bright lights. Many people with dense cataracts complain of glare while driving at night ... the headlights from oncoming traffic make it hard to see. Glare is usually associated with cataracts and one of the indicators that it may be time for cataract surgery. Another cause of glare is corneal swelling from diseases like Fuchs' dystrophy. Some people have sensitive eyes and seem to suffer from glare without any obvious anatomic abnormalities. Sunglasses during the day may help. At night, a glareresistant coating on glasses may help.
glasses. These are focusing lenses used to improve vision. There are many options when buying a modern set of glasses. For example, you can have them made with bifocals, trifocals, or even a no-line bifocal called a progressive lens. Glasses are also available as transitional lenses that darken when exposed to sunlight.
glasses prescription. A glasses prescription is the little piece of paper that has your spectacle correction written on it. There are many numbers on a glasses prescription and they can be a little daunting to decode if you've never done this before. The first number is your basic refractive error: if you are farsighted this will be a positive number and if nearsighted this will be a negative number. The second number is how much astigmatism you have (if you have any). The last number is a degree measurement used to align the astigmatism glasses in their frames properly. Finally, the "add" is the power of any bifocal correction and can range anywhere from +1.00 to +3.50 depending upon your age and how close to your face you like to read books. OD stands for right eye and OS is the left eye.
glaucoma. Glaucoma is best described as high pressure in the eye that causes damage to the optic nerve. The optic nerve is the large nerve that sends visual information from the eye to the brain. High pressure causes damage to this nerve over time. Glaucoma is a very slow process that usually has no real symptoms other than peripheral vision loss that may go unnoticed until far advanced. Diagnosis is made by measuring the eye pressure, examining various risk factors such as family history and corneal thickness, and by measuring actual damage with optic nerve scans (such as OCT) and visual field testing. Treatment is focused on lowering eye pressure with topical eye drops, laser therapy (SLT), and even surgical treatment (trabeculoplasty or tube-shunt). Most people have chronic open-angle glaucoma and develop visual problems slowly over time. A minority suffer from acute glaucoma and develop acute pain, blurry vision, and extremely high eye pressure. If glaucoma goes unchecked, it will lead to permanent vision loss and even blindness.
OD: - 2.00 + 1.00 x 180 deg
OS: - 1.50 + 0.75 x 020 deg
Bifocal Add: +3.00
glaucoma suspect. This is a person who "might" have glaucoma. The diagnosis of glaucoma is not always an obvious one. There is no "one test" that says if a person has glaucoma. Instead, we look at various risk factors to decide if you look "suspicious enough" to have glaucoma. The most obvious risk factor is high eye pressure. If your pressure is "through the roof" ... then sure, you probably have glaucoma. The difficulty here is that "normal" eye pressure is different for everyone.
Normal pressure ranges from 10 to 21. However, some people have pressures of 25 (or higher) and never develop glaucoma damage. Other people have pressures of 15 and yet are exquisitely sensitive to minor pressure elevations (this condition is referred to as low-tension glaucoma). Other risk factors we look at are family history and circulation problems like migraine headaches. A thin cornea, as measured by pachymetry, has been found to be an independent risk factor for glaucoma, though we don't know why. As glaucoma progresses, damage occurs at the optic nerve in the back of the eye and the optic disk begins to look hollowed out. This is called glaucomatous cupping. Your eye doctor can examine your nerves with a dilated eye exam and look for this appearance, but once again, some people have "suspicious looking nerves," but don't actually have true glaucoma. Finally, we can check for actual vision loss by performing a visual field. Glaucoma damage produces characteristic patterns of vision loss in your peripheral vision. Periodic eye exams are necessary to monitor for pressure fluctuations, photograph optic nerve appearance, and to detect visual field problems. This is all in an attempt to detect early glaucoma so that therapy can start, if needed.
glaucomatous cupping. This is a descriptive term for the changes that occur at the optic nerve from glaucoma damage. The optic nerve is the big nerve that connects the eyeball to the brain. It is located at the back of the eye, and its insertion can be seen inside the eye in the retina. This nerve is like a tube or pipe, with over a million individual nerve cell "wires" running through it ... kind of like a bundle of wires running through a PVC pipe. With glaucoma, the nerve fibers die off one by one and eventually disappear. With time, this creates a hollowed out appearance to the optic nerve which can be seen during an exam. This hollowed out appearance looks like the inside of a bowl or "cup" and is called glaucomatous cupping. People with advanced glaucoma have significant cupping with hollowed out optic nerves. Some people have the appearance of glaucomatous cupping, but in reality have perfectly normal eyes. This is because some people are born with larger optic nerves ... their "pipe" is very large with a lot of excess room inside of it that gives the illusion of nerve loss, but in reality they are perfectly healthy. This anatomical variety is one of the reasons eye doctors take photos and scans of the optic nerve - to see if "cupping" has gotten worse over time.
gonioscopy. This is the eye exam technique used to examine the drainage angle inside the eye, and is used to evaluate for glaucoma. The front part of the eye is filled with a fluid called the aqueous humor. This fluid nourishes many structures inside the eye and the balance of aqueous production and drainage is what controls the overall pressure of the eye. The aqueous "drain" is called the trabecular meshwork and is located in a 360-degree ring ... right at the point where the iris (the colored part of the eye) intersects with the sclera (the white of the eye). This drainage intersection is also known as the "angle" because of the insertion anatomy. Some people are at risk for their angle to narrow and close, leading to complete blockage of the drain which causes an acute glaucoma. It is useful for an eye doctor to examine this angle in order to let their patients know their risk for having one of these glaucoma attacks. Unfortunately, the angle is a little difficult to see, even with a microscope, because of its interior location. Gonioscopy is the technique where a special lens containing mirrors (a goniolens) is placed onto the surface of the eye. The doctor then looks through this lens/mirror device to see how "open" the angle appears. If the angle seems very tight, the risk of an acute glaucoma attack is high, and a prophylactic LPI laser procedure can be performed to decrease this risk.
GPC. This stands for Giant Papillary Conjunctivitis and is sometimes called "contact lens overwear syndrome." Contacts are made of plastic, but at a microscopic level they look like a sponge full of water. Just like a sponge, contacts tend to suck up irritants from the environment. Contacts also block the amount of oxygen the cornea normally absorbs from the air around us. This combination of irritants can aggravate the ocular surface and create a temporary inflammatory reaction. The eye becomes irritated and intolerant to contact lens wear. On exam, the eye looks red and may even have focal spots of inflammation on the cornea itself. When the eyelids are flipped over, giant papillary "bumps" can be seen - they look similar to allergic hives that you get on the skin. GPC tends to occur more in people who wear their contacts for extended periods or who sleep in their contacts, though sometimes we see this in people who are very conscientious with their ocular hygiene. Treatment usually involves a contact lens "holiday" to let the eyes recover. Rewetting drops, allergy drops, and occasionally a mild steroid can speed the healing process. Hopefully, after a few weeks of rest, contacts can slowly be resumed.
Graves' disease. Graves' disease is an autoimmune disorder where the thyroid pumps out too much thyroid hormone. Graves' is the most common cause for hyperthyroidism and is more common with women. Graves' can cause ocular problems such as eyelid retraction (giving people a wide-eyed appearance) and swelling of the eye muscles located behind the eye. This swelling causes the eye to protrude forward – a condition called proptosis or exophthalmos. Protrusion can cause extreme dry eye and exposure problems if the eyelids don't close completely while sleeping. Double vision is common secondary to the eye muscle involvement. If bad enough, muscle swelling can push on the optic nerve behind the eye and create neurologic vision loss. Treatment is geared toward normalizing thyroid levels and lubricating the eye. If double vision is constant, strabismus surgery can be considered. Decompression surgery (usually with an ENT doctor or an oculoplastic surgeon) is sometimes performed to give the eye more room inside the eye socket.