Eye Dictionary: F
F
farsightedness. This is a refractive error where close vision isblurry while distance vision is clearer. This situation occurs because the eye's focus is too "weak." Let me explain. Normally, the eye works like a camera with light entering the eye being focused perfectly on the retina - the retina is like the film in a camera, located in the back of the eye. When a person is farsighted, however, light wants to focus behind the retina and visual images look blurry. By strengthening the eye focusing power with glasses, light can focus properly on the retina. Many children are born slightly farsighted, yet still have excellent vision. This is because they have strong intraocular eye muscles that can change the shape of their lens (a process called accommodation) and see clearly. We lose this focal plasticity with age (a process called presbyopia) and most adults with farsightedness require glasses for BOTH distance and near vision.
femtosecond laser. A type of laser that delivers energy in superfast spurts, coming out in rapid pulses like a miniature machine gun. This technology allows a laser to make finely controlled cuts in the cornea and helps in the creation of the "flap" during LASIK surgery - this is called Intralase. The femtosecond laser is occasionally used in cataract surgery, though its usefulness for intraocular surgery seems limited.
flashes. If you are seeing flashing lights in your vision, you are probably suffering from a vitreous detachment. This is when the vitreous jelly inside the eye contracts and peels off the retina. Many people describe seeing a flash like a "streak or arc of lightening" in their peripheral vision. While a vitreous detachment is relatively benign, those flashes can be the harbinger of more serious problems like a retinal detachment. Another cause for a "flash" is a migraine aura ... this is a special kind of headache that causes lights or waviness to the vision. These aren't truly flashes, however, as they usually persist for 15-30 minutes. New flashes warrant a dilated eye exam to rule out retinal
problems.
flaxseed. Flaxseed and other plant-based foods contain omega-3 fatty acids that may be helpful in the treatment of macular degeneration (along with the heart benefits of the Omega-3 supplements). However, flaxseed contains mainly the ALA fatty acid ... not the EPA and DHA that are being studied in the AREDS2 Study. For the prevention of macular degeneration, traditional fish oils are probably better ... with flaxseed reserved for vegetarians and people allergic to fish. Those limitations aside, flaxseed fatty acids may be good for oil flow and so may be helpful for the meibomian gland dysfunction of blepharitis. Ground flaxseed is good; however, flaxseed oil can go rancid quickly (there is some question in the literature as to whether the oil can increase men's risk of prostate cancer).
FLT laser. This stands for Focal Laser Therapy and is the term used to describe most laser treatments used on the retina. For example, FLT laser can be used to seal leaking microaneurysms from diabetic retinopathy. Larger areas of retinal swelling and macular edema can be treated with FLT laser spots applied in a grid pattern to help peg the retina back into place. Small retinal tears can be isolated by sealing the surrounding retinal tissue with FLT laser spots - this keeps the tear from extending and turning into a retinal detachment. FLT laser spots are targeted to specific areas of the retina and is different than PRP (panretinal photocoagulation). With PRP, hundreds of laser spots are created throughout the entire peripheral retina in an attempt to save the central vision (typically used in cases of neovascularization from diabetic retinopathy or a CRVO).
floaters. These are little spots floating in the vision, which usually occur secondary to aging changes in the vitreous jelly that fills the eye. They are best seen when looking at plain surfaces like a blank wall or the sky and tend to move or "float" around with eye movements. While annoying, floaters are usually harmless. Sudden onset of floaters usually occurs from a vitreous detachment, which is a sudden contracture of the vitreous gel and is associated with aging. Floaters can also be a symptom of more serious problems like a vitreous hemorrhage or even a retinal detachment. New floaters need to be evaluated with a dilated eye exam to rule out serious pathology.
Flomax. This is the trade name for tamsulosin, an oral medication used for urinary problems in men with enlarged prostates. This medicine helps by relaxing smooth muscle in the urinary track, but it also relaxes the smooth muscle in the iris, causing floppy iris syndrome. This creates challenges during cataract surgery.
floppy iris syndrome. This is an over-relaxation of the iris, usually caused by urinary medications like Flomax, that makes cataract surgery more difficult. The iris is the colored part of the eye – some people have blue irises and others have brown. The iris is a muscle as well, and this muscle makes your pupil large or small depending upon ambient lighting. Urinary medications like Flomax make your iris muscle "relax" and become "floppy." This relaxation can be so intense that
when we make our initial microincision into the eye during surgery, the iris can bulge forward and actually block that incision! This makes surgery challenging, as you can imagine. There are many modern methods to deal with floppy iris ... but there is no doubt that Flomax makes cataract surgery difficult. This is especially true if your cataract is extremely dense or you don't dilate well. Floppy iris syndrome is something we see a lot in ophthalmology and the prevalence is increasing (Flomax has gone generic so we're seeing more usage). Other urinary drugs associated with floppy iris include Hytrin (terazosin), Cardura (doxazosin), and Uroxatral (alfuzosin).
fluorescein. This is a yellow dye used during an eye exam. This dye is an organic pigment similar to the pigments used in a highlighter ... at least in the sense that it glows under a blue or "black" light. This glowing property is useful for checking eye pressure during applanation tonometry. Fluorescein is also useful for detecting small scratches on the cornea (see corneal abrasion) or foreign bodies that are otherwise hard to see. These irritants may not be obvious to the doctor at first glance, but they glow brightly under the microscope with the help of fluorescein dye.
Fluorescein is used for many applications outside of ophthalmology. For example, the yellow dye is used in bubble levels attached to work tools.
fluorescein angiogram. This is a diagnostic test performed by retina specialists to evaluate circulatory problems in the retina. Fluorescein is a harmless yellow dye that has the unique property that it glows under a blue/black light. This dye can be injected into the arm and introduced into the blood stream. As the dye works its way into the eye, photographs of the retina are taken every few seconds to look for leaking areas or structural problems. This is particularly useful in detecting vessel
leakage from macular degeneration and diabetic retinopathy, with the results helping to guide treatment. While this test is relatively innocuous, a small percentage of people have a temporary allergic reaction to the injection.
fluoroquinolone. This is a class of powerful antibiotics that is commonly used to treat eye infection and used as prophylactic treatment after cataract surgery to decrease the chance of endophthalmitis. These antibiotics are considered "broad spectrum" and are good for treating a myriad of different bacterial infections, including the dreadedpseudomonas infection common with contact lens wearers. Examples of second-generation fluoroquinolones are ciprofloxacin (a.k.a. "cipro") and ofloxacin. The newest generation of fluoroquinolones (gatifloxacin, moxifloxacin, and besifloxacin) are quite powerful and usually reserved for more serious infections such as a corneal ulcer. In the arsenal of available eye antibiotics, fluoroquinolones are generally considered the most powerful (and expensive). The only antibiotic more powerful would be specially prepared fortified antibiotics mixed up by a compounding pharmacy.
fluorometholone. A mild steroid eye drop. Also available under the trade name FML.
FML. Trade name for the drug fluorometholone. This is a mild steroid used to treat surface ocular inflammation.
foreign body. When a piece of dirt, plant, or metal gets into the eye, we call this a foreign body. Any foreign object in the eye will cause pain, watering, and occasionally an allergic response with swelling of the conjunctiva (the white part of the eye). Debris can scratch the cornea, causing further pain and increasing the chance of infection. The eye has more sensory nerve endings than anywhere else in the body ... even after a foreign body washes out, the eye can still hurt and feel as if there is something present. Metal foreign bodies are particularly nasty as metal pieces tend to stick to the cornea and rust into place. All foreign bodies need to be removed before the area becomes infected. This is done in the office at the slit lamp microscope using topical anesthesia drops - foreign body removal is a little nerve-wracking for the patient but surprisingly painless.
.
fortified antibiotics. These are antibiotic eye drops especially made by a compounding pharmacy, used for bad eye infections such as a corneal ulcer. Certain strong medicines are not available in eye drop format (or don't come in high enough concentrations). If you have a bad corneal ulcer, for example, the typical antibiotic eye drops may not be strong enough. In these cases, we typically have a compounding pharmacy prepare fortified antibiotic drops. The most common drops we have created are vancomycin (an antibiotic good for MRSA), tobramycin (good general coverage), and amphotericin B (an antifungal agent).
fourth nerve palsy. This is a paralysis or stroke to the fourth cranial nerve. This nerve controls a single eye muscle called the superior oblique muscle. This muscle is located behind the eyeball and it helps the eye look downward and assists with eye rotation when you tilt your head sideways. When the nerve is blocked, this muscle stops working, and people complain of vertical double vision where objects look stacked on top of each other. The double vision may get worse when looking to the side or trying to read a book. Fourth nerve palsies can be subtle. In fact, this is the hardest cranial nerve palsy to detect as the eyes appear normal to casual inspection. There are many causes for a 4th nerve palsy: congenital, trauma, vascular insults (hypertension/diabetes), and lesions in the brain. If there isn't an obvious cause for a nerve palsy, then further imaging such as MRI should be obtained. If the double vision persists, prism glasses are an option as is strabismus surgery.
fovea. This spot in the retina that is responsible for the exact center of our vision. The retina works like film in a camera and detects light. The most important part of the retina is the macula, which corresponds to our central vision. In the exact center of our macula is a small depression in the retina called the fovea. This is the most sensitive part of the entire retina and corresponds to your extreme central vision. For example, if you closely examine the period printed at the end of this sentence, the light bouncing off that period is focused directly onto your fovea. On a dayto- day basis, most eye doctors don't talk about the fovea but discuss the larger macular area in general. The fovea is more of an anatomical landmark seen on retinal scans like the OCT or fluorescein angiogram.
FreshKote. A prescription rewetting drop that contains several substances designed to replenish multiple layers of the tear film. It also has a higher osmotic (concentration) content than normal tears, which serves to help flatten the cornea cell layers and may be helpful for treating cloudy corneas (such as with Fuchs' dystrophy and recurrent erosions).
fresnel lens. A fresnel lens is a magnifying lens that is built into a flat piece of plastic. You may have seen fresnel magnifiers in a bookstore … they look like a clear, flexible sheet of plastic with tiny ridges along the surface. They are commonly used in overhead projectors and rear projection screen televisions. Fresnel lenses can be made very flat. Because of the many "ridge lines," they are not as clear as a normal lens, so they have limited use in eye care. The one exception is that a type of fresnel lens is used in multifocal implants like the Restor lens. This is a premium implant used in cataract surgery that has a bifocal built in. The implant has concentric rings built into its surface, with half the rings focused at distance and the other half focused for near. This technology can get people out of reading glasses after cataract surgery, though the fresnel effect can create visual side effects like ring halos and some loss of clarity.
fresnel stick-on prism. This is an adhesive prism that is stuck onto your glasses as a temporary method of fixing double vision. Prism glasses can be very effective for correcting alignment problems (diplopia). However, prism glasses are expensive and notoriously difficult to get made correctly. In some cases, I'll prescribe a temporary "stick-on" prism. It is a clear sticker, similar to a fresnel lens, that is cut out to the size of your glasses and adhered to the surface of the lens. This is cheaper then getting new glasses and allows you to see if you will tolerate the prism correction before more expensive prism glasses are made. The stick-on prism is somewhat unsightly, however, and not as clear as "normal glass" so is not a long-term solution.
Fuchs' Dystrophy. This is a condition where the cornea gets too wet and cloudy. The cornea (the clear window that makes up the front of the eye) is clear because it is relatively dehydrated compared to the rest of the eyeball. This may seem counterintuitive at first. After all, isn't the eye covered by tears on the outside and the inside of the eye filled with aqueous fluid? How can the cornea be dry? The cornea is dry because the innermost layer of the cornea has tiny cells that act like "bilge pumps," sucking water out of the cornea and continuously pumping that water back inside the eye. People with Fuchs' have less of these pump cells than normal and are at risk for their cornea getting too boggy and cloudy. This is especially true after eye surgery, as surgical trauma tends to shock a certain number of these pump cells so that they stop working. If the cornea gets wet enough to affect vision, then a corneal transplant may be needed. DSEK surgery is a newer type of transplant where only the inner layers of the cornea (including the pump layer) are replaced. Early treatments include hyperosmotic drops like Muro 128 and FreshKote. Glaucoma drops can help to lower the internal ocular pressure so that the pump cells don't have to work so hard.
fundus. This is another way of saying retina. The fundus describes the back portion of the retina that is visible using the eye microscope. For example, doctors use a "fundus camera" to take pictures of the retina. Fundus is a Latin term that means 'bottom' and is used to describe organ parts that look like the inside of a bowl. There is also a 'fundus' in the stomach, bladder, and in the uterus.
femtosecond laser. A type of laser that delivers energy in superfast spurts, coming out in rapid pulses like a miniature machine gun. This technology allows a laser to make finely controlled cuts in the cornea and helps in the creation of the "flap" during LASIK surgery - this is called Intralase. The femtosecond laser is occasionally used in cataract surgery, though its usefulness for intraocular surgery seems limited.
flashes. If you are seeing flashing lights in your vision, you are probably suffering from a vitreous detachment. This is when the vitreous jelly inside the eye contracts and peels off the retina. Many people describe seeing a flash like a "streak or arc of lightening" in their peripheral vision. While a vitreous detachment is relatively benign, those flashes can be the harbinger of more serious problems like a retinal detachment. Another cause for a "flash" is a migraine aura ... this is a special kind of headache that causes lights or waviness to the vision. These aren't truly flashes, however, as they usually persist for 15-30 minutes. New flashes warrant a dilated eye exam to rule out retinal
problems.
flaxseed. Flaxseed and other plant-based foods contain omega-3 fatty acids that may be helpful in the treatment of macular degeneration (along with the heart benefits of the Omega-3 supplements). However, flaxseed contains mainly the ALA fatty acid ... not the EPA and DHA that are being studied in the AREDS2 Study. For the prevention of macular degeneration, traditional fish oils are probably better ... with flaxseed reserved for vegetarians and people allergic to fish. Those limitations aside, flaxseed fatty acids may be good for oil flow and so may be helpful for the meibomian gland dysfunction of blepharitis. Ground flaxseed is good; however, flaxseed oil can go rancid quickly (there is some question in the literature as to whether the oil can increase men's risk of prostate cancer).
FLT laser. This stands for Focal Laser Therapy and is the term used to describe most laser treatments used on the retina. For example, FLT laser can be used to seal leaking microaneurysms from diabetic retinopathy. Larger areas of retinal swelling and macular edema can be treated with FLT laser spots applied in a grid pattern to help peg the retina back into place. Small retinal tears can be isolated by sealing the surrounding retinal tissue with FLT laser spots - this keeps the tear from extending and turning into a retinal detachment. FLT laser spots are targeted to specific areas of the retina and is different than PRP (panretinal photocoagulation). With PRP, hundreds of laser spots are created throughout the entire peripheral retina in an attempt to save the central vision (typically used in cases of neovascularization from diabetic retinopathy or a CRVO).
floaters. These are little spots floating in the vision, which usually occur secondary to aging changes in the vitreous jelly that fills the eye. They are best seen when looking at plain surfaces like a blank wall or the sky and tend to move or "float" around with eye movements. While annoying, floaters are usually harmless. Sudden onset of floaters usually occurs from a vitreous detachment, which is a sudden contracture of the vitreous gel and is associated with aging. Floaters can also be a symptom of more serious problems like a vitreous hemorrhage or even a retinal detachment. New floaters need to be evaluated with a dilated eye exam to rule out serious pathology.
Flomax. This is the trade name for tamsulosin, an oral medication used for urinary problems in men with enlarged prostates. This medicine helps by relaxing smooth muscle in the urinary track, but it also relaxes the smooth muscle in the iris, causing floppy iris syndrome. This creates challenges during cataract surgery.
floppy iris syndrome. This is an over-relaxation of the iris, usually caused by urinary medications like Flomax, that makes cataract surgery more difficult. The iris is the colored part of the eye – some people have blue irises and others have brown. The iris is a muscle as well, and this muscle makes your pupil large or small depending upon ambient lighting. Urinary medications like Flomax make your iris muscle "relax" and become "floppy." This relaxation can be so intense that
when we make our initial microincision into the eye during surgery, the iris can bulge forward and actually block that incision! This makes surgery challenging, as you can imagine. There are many modern methods to deal with floppy iris ... but there is no doubt that Flomax makes cataract surgery difficult. This is especially true if your cataract is extremely dense or you don't dilate well. Floppy iris syndrome is something we see a lot in ophthalmology and the prevalence is increasing (Flomax has gone generic so we're seeing more usage). Other urinary drugs associated with floppy iris include Hytrin (terazosin), Cardura (doxazosin), and Uroxatral (alfuzosin).
fluorescein. This is a yellow dye used during an eye exam. This dye is an organic pigment similar to the pigments used in a highlighter ... at least in the sense that it glows under a blue or "black" light. This glowing property is useful for checking eye pressure during applanation tonometry. Fluorescein is also useful for detecting small scratches on the cornea (see corneal abrasion) or foreign bodies that are otherwise hard to see. These irritants may not be obvious to the doctor at first glance, but they glow brightly under the microscope with the help of fluorescein dye.
Fluorescein is used for many applications outside of ophthalmology. For example, the yellow dye is used in bubble levels attached to work tools.
fluorescein angiogram. This is a diagnostic test performed by retina specialists to evaluate circulatory problems in the retina. Fluorescein is a harmless yellow dye that has the unique property that it glows under a blue/black light. This dye can be injected into the arm and introduced into the blood stream. As the dye works its way into the eye, photographs of the retina are taken every few seconds to look for leaking areas or structural problems. This is particularly useful in detecting vessel
leakage from macular degeneration and diabetic retinopathy, with the results helping to guide treatment. While this test is relatively innocuous, a small percentage of people have a temporary allergic reaction to the injection.
fluoroquinolone. This is a class of powerful antibiotics that is commonly used to treat eye infection and used as prophylactic treatment after cataract surgery to decrease the chance of endophthalmitis. These antibiotics are considered "broad spectrum" and are good for treating a myriad of different bacterial infections, including the dreadedpseudomonas infection common with contact lens wearers. Examples of second-generation fluoroquinolones are ciprofloxacin (a.k.a. "cipro") and ofloxacin. The newest generation of fluoroquinolones (gatifloxacin, moxifloxacin, and besifloxacin) are quite powerful and usually reserved for more serious infections such as a corneal ulcer. In the arsenal of available eye antibiotics, fluoroquinolones are generally considered the most powerful (and expensive). The only antibiotic more powerful would be specially prepared fortified antibiotics mixed up by a compounding pharmacy.
fluorometholone. A mild steroid eye drop. Also available under the trade name FML.
FML. Trade name for the drug fluorometholone. This is a mild steroid used to treat surface ocular inflammation.
foreign body. When a piece of dirt, plant, or metal gets into the eye, we call this a foreign body. Any foreign object in the eye will cause pain, watering, and occasionally an allergic response with swelling of the conjunctiva (the white part of the eye). Debris can scratch the cornea, causing further pain and increasing the chance of infection. The eye has more sensory nerve endings than anywhere else in the body ... even after a foreign body washes out, the eye can still hurt and feel as if there is something present. Metal foreign bodies are particularly nasty as metal pieces tend to stick to the cornea and rust into place. All foreign bodies need to be removed before the area becomes infected. This is done in the office at the slit lamp microscope using topical anesthesia drops - foreign body removal is a little nerve-wracking for the patient but surprisingly painless.
.
fortified antibiotics. These are antibiotic eye drops especially made by a compounding pharmacy, used for bad eye infections such as a corneal ulcer. Certain strong medicines are not available in eye drop format (or don't come in high enough concentrations). If you have a bad corneal ulcer, for example, the typical antibiotic eye drops may not be strong enough. In these cases, we typically have a compounding pharmacy prepare fortified antibiotic drops. The most common drops we have created are vancomycin (an antibiotic good for MRSA), tobramycin (good general coverage), and amphotericin B (an antifungal agent).
fourth nerve palsy. This is a paralysis or stroke to the fourth cranial nerve. This nerve controls a single eye muscle called the superior oblique muscle. This muscle is located behind the eyeball and it helps the eye look downward and assists with eye rotation when you tilt your head sideways. When the nerve is blocked, this muscle stops working, and people complain of vertical double vision where objects look stacked on top of each other. The double vision may get worse when looking to the side or trying to read a book. Fourth nerve palsies can be subtle. In fact, this is the hardest cranial nerve palsy to detect as the eyes appear normal to casual inspection. There are many causes for a 4th nerve palsy: congenital, trauma, vascular insults (hypertension/diabetes), and lesions in the brain. If there isn't an obvious cause for a nerve palsy, then further imaging such as MRI should be obtained. If the double vision persists, prism glasses are an option as is strabismus surgery.
fovea. This spot in the retina that is responsible for the exact center of our vision. The retina works like film in a camera and detects light. The most important part of the retina is the macula, which corresponds to our central vision. In the exact center of our macula is a small depression in the retina called the fovea. This is the most sensitive part of the entire retina and corresponds to your extreme central vision. For example, if you closely examine the period printed at the end of this sentence, the light bouncing off that period is focused directly onto your fovea. On a dayto- day basis, most eye doctors don't talk about the fovea but discuss the larger macular area in general. The fovea is more of an anatomical landmark seen on retinal scans like the OCT or fluorescein angiogram.
FreshKote. A prescription rewetting drop that contains several substances designed to replenish multiple layers of the tear film. It also has a higher osmotic (concentration) content than normal tears, which serves to help flatten the cornea cell layers and may be helpful for treating cloudy corneas (such as with Fuchs' dystrophy and recurrent erosions).
fresnel lens. A fresnel lens is a magnifying lens that is built into a flat piece of plastic. You may have seen fresnel magnifiers in a bookstore … they look like a clear, flexible sheet of plastic with tiny ridges along the surface. They are commonly used in overhead projectors and rear projection screen televisions. Fresnel lenses can be made very flat. Because of the many "ridge lines," they are not as clear as a normal lens, so they have limited use in eye care. The one exception is that a type of fresnel lens is used in multifocal implants like the Restor lens. This is a premium implant used in cataract surgery that has a bifocal built in. The implant has concentric rings built into its surface, with half the rings focused at distance and the other half focused for near. This technology can get people out of reading glasses after cataract surgery, though the fresnel effect can create visual side effects like ring halos and some loss of clarity.
fresnel stick-on prism. This is an adhesive prism that is stuck onto your glasses as a temporary method of fixing double vision. Prism glasses can be very effective for correcting alignment problems (diplopia). However, prism glasses are expensive and notoriously difficult to get made correctly. In some cases, I'll prescribe a temporary "stick-on" prism. It is a clear sticker, similar to a fresnel lens, that is cut out to the size of your glasses and adhered to the surface of the lens. This is cheaper then getting new glasses and allows you to see if you will tolerate the prism correction before more expensive prism glasses are made. The stick-on prism is somewhat unsightly, however, and not as clear as "normal glass" so is not a long-term solution.
Fuchs' Dystrophy. This is a condition where the cornea gets too wet and cloudy. The cornea (the clear window that makes up the front of the eye) is clear because it is relatively dehydrated compared to the rest of the eyeball. This may seem counterintuitive at first. After all, isn't the eye covered by tears on the outside and the inside of the eye filled with aqueous fluid? How can the cornea be dry? The cornea is dry because the innermost layer of the cornea has tiny cells that act like "bilge pumps," sucking water out of the cornea and continuously pumping that water back inside the eye. People with Fuchs' have less of these pump cells than normal and are at risk for their cornea getting too boggy and cloudy. This is especially true after eye surgery, as surgical trauma tends to shock a certain number of these pump cells so that they stop working. If the cornea gets wet enough to affect vision, then a corneal transplant may be needed. DSEK surgery is a newer type of transplant where only the inner layers of the cornea (including the pump layer) are replaced. Early treatments include hyperosmotic drops like Muro 128 and FreshKote. Glaucoma drops can help to lower the internal ocular pressure so that the pump cells don't have to work so hard.
fundus. This is another way of saying retina. The fundus describes the back portion of the retina that is visible using the eye microscope. For example, doctors use a "fundus camera" to take pictures of the retina. Fundus is a Latin term that means 'bottom' and is used to describe organ parts that look like the inside of a bowl. There is also a 'fundus' in the stomach, bladder, and in the uterus.