Eye Dictionary: Q-R
R
radial keratotomy. Also called "RK," this is an older refractive surgery style in which a diamond knife is used to make radial cuts in the cornea. These incisions change the shape of the cornea and can correct nearsightedness. This technique was invented by a Russian ophthalmologist in the '70s and was very popular in the '80s and early '90s. While effective, some people with RK continue to have corneal shape fluctuations decades later and go on to become farsighted. While a successful procedure, this technique has since been supplanted by more predictable laser procedures like LASIK and PRK.
reading glasses. These are glasses that are focused for viewing near objects ... such as when reading a book. Inexpensive, over-thecounter reading glasses work well for many people and range in diopter power from weak +1.00 glass, all the way up to +3.50 readers. The power of your "cheaters" depends upon your age and how close you like to hold books to your face. If you have significant refractive error (nearsightedness, farsightedness, or astigmatism) you may require prescription reading glasses (or a bifocal) for best vision. Also, keep in mind that cheap OTC reading glasses are designed to fit the average person ... if your eyes are narrow or wide-set, they may not be as comfortable or clear as a custom glass. Your need for reading glasses occurs because of presbyopia (aging changes inside the eye), and is normal after the age of forty.
recurrent erosion. This is a corneal abrasion that recurs because it doesn't "heal right," kind of like a skin cut that keeps reopening. The cornea is the clear structure that lies at the front of the eye, forming the ocular surface that allows light to enter the eye. The cornea is relatively tough but it is covered by a more delicate layer of skin called the corneal "epithelium." The corneal skin is thin and can easily rub or scratch off due to trauma or abrasion caused by a piece of sand in the eye. Surface scratches are called "corneal abrasions" and can cause much discomfort. A recurrent erosion occurs when the epithelial skin doesn't heal well enough to the cornea. Repeated blinking can cause the corneal epithelium to scratch off again. This usually happens in the morning when the eyes are most dry. When the eyes pop open, the suction pulls off the epithelium again. This repetitive process can make the erosion take forever to heal. You can almost imagine that the surface epithelium is like a carpet that grows back over a concrete foundation. With recurrent erosion, the concrete gets "sandy" or "rough" in one spot such that carpet has a hard time tacking down in that particular area. Treatment for a recurrent erosion usually begins with aggressive night-time lubrication and ointments but can expand to include night-time patching and bandage contact lenses. If these aren't working, more aggressive surgical treatments can be considered, such as polishing the underlying cornea with a diamond burr or stromal puncture (using a needle to create small divots in the cornea for the surface epithelium to grow down into and stick better).
refraction. This is the method used to determine someone's glasses prescription. Most refraction is performed with a phoropter. This is the optical device you look through while reading an eye chart - it contains lenses and can be used to determine your refractive error (nearsightedness and farsightedness) and correct astigmatism. Refraction requires feedback from our patients, so this technique can be especially tough in children and in non-verbal people (ex.: dementia). The range of potential refractive error is huge, so it is very helpful to have our patients bring their current glasses in to the office to be measured. These measurements are a starting point for the refraction process. It is also helpful to know the current glasses prescription so that we can advise our patients whether it is "worth it" to update their current spectacles.
refractive error. This is the degree to which you need glasses. Examples of refractive error are nearsightedness or farsightedness. Astigmatism is another refractive error. Your refractive error is obtained with refraction, typically with a phoropter machine in the eye doctor's office.
Refresh. A popular brand of artificial tear (rewetting drop). Refresh comes in different consistencies, including the thicker Refresh PM (a rewetting ointment that can be used at bedtime).
Rescula. This is a new glaucoma drop that has recently "re-entered" the market. This medication is similar to the prostaglandin glaucoma drop latanoprost, but seems to have a slightly different mechanism of action and is not as strong acting. I utilize this drop rarely in my own practice, but it may be good for people who can't tolerate a more powerful prostaglandin and the side effects of beta-blocker drops such as timolol. Rescula may also be a "last ditch" additional drop for people with uncontrolled glaucoma who are already taking every other drop available. It is not clear if Rescula has any added benefit in this setting, however.
Restasis. This is an eye drop with cyclosporine used for treating dry eye. This medication improves both the quantity and quality of the tear film. Unfortunately, it can be expensive (this is getting better), stings going in, and takes a good month before improvement is seen. Also, it doesn't work for everyone. On the other hand, most people with dry eye are desperate for relief so if the drop works, it is worth the hassle. If you develop an eye infection, temporarily stop this medication as it can make viral infections worse. This drop is usually dosed as a single drop twice a day.
Restor lens. This is a multifocal implant using during cataract surgery that can give good distance and near vision without requiring glasses. With cataract surgery, the cloudy lens is removed from the eye and replaced by a plastic "implanted" lens. A new lens is required to see clearly. The standard lens most people opt for is in focus only for far distance, and you still need reading glasses afterward. Newer lenses, like the Restor lens, have a bifocal built into the implant itself and can give
good distance AND near vision. This technology is useful for active people who wish to decrease their reliance on spectacles. The technology comes at a price, however, as medical insurance won't pay for the additional cost of this implant. Also, there are some mild visual tradeoffs with multifocal implants such as seeing rings around lights at night.
retina. The retina is the light sensitive structure in the back of the eye that detects images and converts light into signals that our brain can understand. The retina works like "film in a camera." When light enters the eye, it travels through the cornea in the front, through the dark pupil, through the lens/cataract, before striking the retina in the back. The retina is a pretty remarkable structure because of its high resolution and ability to detect light in very dark situations. The photoreceptors (rods and cones) detect black and white and color light, respectively. The macula is the central area of the retina that is responsible for our central vision. There are more photoreceptors packed in this area to allow high resolution central vision.
retinal detachment. This is when the retina peels off in the back of the eye, leading to catastrophic vision loss. Because the retina works like film in a camera, it needs to be perfectly smooth and flat to take a good "picture." The retina is plastered smooth against the inner eye like wallpaper. A retinal detachment occurs when the retina begins to peel off (like wallpaper coming off a wall). There are many potential causes for a detachment. Most occur secondary to aging changes in the vitreous jelly that fills the eye. The vitreous is a gel-like fluid that fills the back of the eye. As we age, this jelly liquefies and becomes watery, and then can contract inwards. This contraction is called a vitreous detachment and is almost always a normal and harmless event. However, sometimes the vitreous gel can pull on the retinal surface and create a small tear in the retina. This tear can extend and turn into an actual retinal detachment. There are other causes for detachment, such as traction caused by diabetic retinopathy and even tumors, though these are rare. A detached retina can cause significant vision loss, especially if the macula (the part of the retina responsible for fine central vision) has detached as well. There are many methods for repairing a detachment, depending upon the severity of findings. Lasers can be used to seal a retinal tear. A vitrectomy is often required. This is a surgical procedure where a retina specialist removes the vitreous jelly from the eye in order to remove this as a source of traction. Gas bubbles are sometimes injected to hold the retina in place (a pneumatic retinopexy), and sometimes a silicone buckle (called a scleral buckle) is sewn around the outside of the eye to keep the retina in place.
retina specialist. This is an ophthalmologist (MD) who goes on to sub-specialize in the treatment of retina problems. Retina doctors perform surgeries to correct retinal problems such as retinal detachments and membrane peels. They also treat wet macular degeneration, performing injection procedures and advanced retinal laser procedures. These doctors don't typically perform other eye services such as refraction for glasses, nor do they treat problems like glaucoma or cataracts.
retinitis pigmentosa. A genetic disorder of the retina that causes gradual vision loss. With retinitis pigmentosa (sometimes called RP) the photoreceptors (rods and cones of the retina) or their supporting cells gradually stop working, affecting vision. Some people develop visual loss in infancy while others have problems later in life. Often the rods (the photoreceptors responsible for peripheral and night vision) are involved such that the vision constricts inward making it hard to see in the periphery. Night vision is often severely diminished. There are over 80 different types of retinitis pigmentosa that have been discovered. Some are inherited from family, some occur by recessive mutations that only occur when two parents with the same gene defect have a child. Some
kinds of RP are sporadic with no family history at all. There have not been found to be any effective treatments for retinitis pigmentosa, though some retina doctors have tried high levels of vitamin A in the past. There is vigorous ongoing research looking for a cure for this disorder.
retinoscope. This is a hand-held tool the eye doctor uses to estimate refractive error such as nearsightedness, farsightedness, and astigmatism. This tool is challenging to learn and not as accurate as a true phoropter refraction. However, this is often the only method of determining a glasses prescription in a young child or non-verbal patient who can't give feedback while reading an eye chart. The retinoscope can also be used to determine a baseline prescription before refining the
glasses prescription using the phoropter.
retrobulbar block. This is a more intense way of numbing and paralyzing the eye before difficult eye surgery. Cataract surgery is normally performed under topical anesthesia - simple numbing drops placed on the eye while the patient remains awake. However, if we anticipate that a cataract surgery may take longer than usual (a dense cataract) or may require more manipulation (such as pupil stretching) than a "block" can be considered. With this technique, our patient is temporarily sedated by an anesthesiologist and put completely asleep for about 1-2 minutes. While asleep, the doctor (anesthesiologist or ophthalmologist) injects the retrobulbar numbing agent behind the eyeball itself. This completely numbs the eye and paralyzes the muscles that control eye movement and blinking. This makes the surgery much easier as there is no chance for pain or any unexpected eye movements during the procedure. The downside to a retrobulbar block is that it is
more invasive and may require clearance from a primary doctor first. If on blood thinners, these will need to be stopped ahead of time to decrease the chance of bleeding behind the eye from the injection. Finally, the temporary eyelid paralysis means the eye has a harder time closing immediately after surgery and may need to be patched shut overnight to keep the eye from drying out. This is inconvenient and may require a "safety stitch" during the surgery that extends operating time. In our patient population here in Daytona Beach, about one in twenty people require one of these blocks. In other parts of the world where everyone has a terrible, dense cataract (India for example) the majority of surgery is done with a retrobulbar block.
rewetting drops. Also known as artificial tears, these eye drops are designed to comfort and improve lubrication of the eyes. These can be bought over the counter and come with various trade names depending upon the manufacturer. Some popular brands are Soothe, Systane, Blink, and Refresh. Most of these drops contain the same ingredients, differing only by what preservative is used. All eye drops need preservatives (such as BAK) to keep them from getting colonized by bacteria floating in the air and on the eyelashes during use. Unfortunately, these preservatives can be harsh on the ocular surface, which is why we don't recommend using artificial tears more than 4-5 times a day. There are preservative free eye drops available that come in single use tear-off dispensers. These are great because they can be used frequently without irritating the eye. They can be expensive, however, and they are not as convenient to carry as you can't screw the caps back on. For most people, regular eye drops work fine with the generic drops working just as well as the fancier brand-name drops. If rewetting drops aren't working, then you can also try rewetting gels. These are like rewetting eye drops, but have a thicker consistency and last longer. The downside to the gels is that they make the vision a little blurry when first applied. For people with very dry eyes or exposure issues at night (for example, the eyelids aren't closing all the way when sleeping), rewetting ointments can be effective. These can be bought over the counter, have a consistency similar to Vaseline, and come in squeezable tubes. Ointments make the vision quite blurry so they are best used at bedtime. Popular brands of ointment include Genteel Gel and Refresh PM (the generic alternatives are just as effective).
rewetting gels. These are a type of rewetting drop that have a thicker consistency, similar to shampoo or pancake syrup (but not sticky, obviously). This thickness keeps the drop from evaporating as quickly so that it lasts longer and gives more relief with dry eye. The downside to these gels, however, is that they make the vision a little blurry when first put in. For most people, the additional lubrication is worth the temporary blurriness. Popular brands include Refresh Liquigel and GenTeal gel, but the generics are just as effective. You can find gel drops at the store mixed in with the regular rewetting drops. If the box has "gel" written in its name, you've found the right stuff.
rewetting ointments. These are thick ointments used for extreme dry eye. As rewetting ointments come in tubes they are challenging to put in the eye and the ointment causes significant blurriness to the vision. As such, they are typically reserved for people with extremely dry corneas that aren't adequately covered with traditional rewetting drops and rewetting gels. Some people have eye exposure problems at night. Their eyelids may not close completely while sleeping, which causes a rough or dry spot. The use of oxygen or sleep apnea machines can exacerbate this. In these cases, a rewetting ointment at bedtime will keep the eye lubricated all night long and hopefully make the eyes feel better the next day. To apply, we have our patient pull the lower eyelid down and apply a small amount of ointment (about the size of a grain of rice) to the inside of the eyelid. Then, blink a few times and the vision should get blurry as the ointment spreads over the surface of the eye. It does not take much ointment to lubricate the eye. If you have a difficult time applying an ointment, you may need help from family members. Rewetting ointments are available over the counter without the need for a prescription. They are located in the same section as the other artificial tears. Popular brands of rewetting ointments include Refresh PM and GenTeal Gel.
RK. This is a surgical procedure where a diamond knife is used to create radial cuts in the cornea. This changes the shape of the ocular surface and can help eliminate nearsightedness. See radial keratotomy for more information on this older refractive surgery.
rod. A type of photoreceptor inside the retina that senses light. Rods are very sensitive and give the eye excellent night vision. Rods can only see in "black and white" in contrast to cones, which are the photoreceptor cells that detect color.
reading glasses. These are glasses that are focused for viewing near objects ... such as when reading a book. Inexpensive, over-thecounter reading glasses work well for many people and range in diopter power from weak +1.00 glass, all the way up to +3.50 readers. The power of your "cheaters" depends upon your age and how close you like to hold books to your face. If you have significant refractive error (nearsightedness, farsightedness, or astigmatism) you may require prescription reading glasses (or a bifocal) for best vision. Also, keep in mind that cheap OTC reading glasses are designed to fit the average person ... if your eyes are narrow or wide-set, they may not be as comfortable or clear as a custom glass. Your need for reading glasses occurs because of presbyopia (aging changes inside the eye), and is normal after the age of forty.
recurrent erosion. This is a corneal abrasion that recurs because it doesn't "heal right," kind of like a skin cut that keeps reopening. The cornea is the clear structure that lies at the front of the eye, forming the ocular surface that allows light to enter the eye. The cornea is relatively tough but it is covered by a more delicate layer of skin called the corneal "epithelium." The corneal skin is thin and can easily rub or scratch off due to trauma or abrasion caused by a piece of sand in the eye. Surface scratches are called "corneal abrasions" and can cause much discomfort. A recurrent erosion occurs when the epithelial skin doesn't heal well enough to the cornea. Repeated blinking can cause the corneal epithelium to scratch off again. This usually happens in the morning when the eyes are most dry. When the eyes pop open, the suction pulls off the epithelium again. This repetitive process can make the erosion take forever to heal. You can almost imagine that the surface epithelium is like a carpet that grows back over a concrete foundation. With recurrent erosion, the concrete gets "sandy" or "rough" in one spot such that carpet has a hard time tacking down in that particular area. Treatment for a recurrent erosion usually begins with aggressive night-time lubrication and ointments but can expand to include night-time patching and bandage contact lenses. If these aren't working, more aggressive surgical treatments can be considered, such as polishing the underlying cornea with a diamond burr or stromal puncture (using a needle to create small divots in the cornea for the surface epithelium to grow down into and stick better).
refraction. This is the method used to determine someone's glasses prescription. Most refraction is performed with a phoropter. This is the optical device you look through while reading an eye chart - it contains lenses and can be used to determine your refractive error (nearsightedness and farsightedness) and correct astigmatism. Refraction requires feedback from our patients, so this technique can be especially tough in children and in non-verbal people (ex.: dementia). The range of potential refractive error is huge, so it is very helpful to have our patients bring their current glasses in to the office to be measured. These measurements are a starting point for the refraction process. It is also helpful to know the current glasses prescription so that we can advise our patients whether it is "worth it" to update their current spectacles.
refractive error. This is the degree to which you need glasses. Examples of refractive error are nearsightedness or farsightedness. Astigmatism is another refractive error. Your refractive error is obtained with refraction, typically with a phoropter machine in the eye doctor's office.
Refresh. A popular brand of artificial tear (rewetting drop). Refresh comes in different consistencies, including the thicker Refresh PM (a rewetting ointment that can be used at bedtime).
Rescula. This is a new glaucoma drop that has recently "re-entered" the market. This medication is similar to the prostaglandin glaucoma drop latanoprost, but seems to have a slightly different mechanism of action and is not as strong acting. I utilize this drop rarely in my own practice, but it may be good for people who can't tolerate a more powerful prostaglandin and the side effects of beta-blocker drops such as timolol. Rescula may also be a "last ditch" additional drop for people with uncontrolled glaucoma who are already taking every other drop available. It is not clear if Rescula has any added benefit in this setting, however.
Restasis. This is an eye drop with cyclosporine used for treating dry eye. This medication improves both the quantity and quality of the tear film. Unfortunately, it can be expensive (this is getting better), stings going in, and takes a good month before improvement is seen. Also, it doesn't work for everyone. On the other hand, most people with dry eye are desperate for relief so if the drop works, it is worth the hassle. If you develop an eye infection, temporarily stop this medication as it can make viral infections worse. This drop is usually dosed as a single drop twice a day.
Restor lens. This is a multifocal implant using during cataract surgery that can give good distance and near vision without requiring glasses. With cataract surgery, the cloudy lens is removed from the eye and replaced by a plastic "implanted" lens. A new lens is required to see clearly. The standard lens most people opt for is in focus only for far distance, and you still need reading glasses afterward. Newer lenses, like the Restor lens, have a bifocal built into the implant itself and can give
good distance AND near vision. This technology is useful for active people who wish to decrease their reliance on spectacles. The technology comes at a price, however, as medical insurance won't pay for the additional cost of this implant. Also, there are some mild visual tradeoffs with multifocal implants such as seeing rings around lights at night.
retina. The retina is the light sensitive structure in the back of the eye that detects images and converts light into signals that our brain can understand. The retina works like "film in a camera." When light enters the eye, it travels through the cornea in the front, through the dark pupil, through the lens/cataract, before striking the retina in the back. The retina is a pretty remarkable structure because of its high resolution and ability to detect light in very dark situations. The photoreceptors (rods and cones) detect black and white and color light, respectively. The macula is the central area of the retina that is responsible for our central vision. There are more photoreceptors packed in this area to allow high resolution central vision.
retinal detachment. This is when the retina peels off in the back of the eye, leading to catastrophic vision loss. Because the retina works like film in a camera, it needs to be perfectly smooth and flat to take a good "picture." The retina is plastered smooth against the inner eye like wallpaper. A retinal detachment occurs when the retina begins to peel off (like wallpaper coming off a wall). There are many potential causes for a detachment. Most occur secondary to aging changes in the vitreous jelly that fills the eye. The vitreous is a gel-like fluid that fills the back of the eye. As we age, this jelly liquefies and becomes watery, and then can contract inwards. This contraction is called a vitreous detachment and is almost always a normal and harmless event. However, sometimes the vitreous gel can pull on the retinal surface and create a small tear in the retina. This tear can extend and turn into an actual retinal detachment. There are other causes for detachment, such as traction caused by diabetic retinopathy and even tumors, though these are rare. A detached retina can cause significant vision loss, especially if the macula (the part of the retina responsible for fine central vision) has detached as well. There are many methods for repairing a detachment, depending upon the severity of findings. Lasers can be used to seal a retinal tear. A vitrectomy is often required. This is a surgical procedure where a retina specialist removes the vitreous jelly from the eye in order to remove this as a source of traction. Gas bubbles are sometimes injected to hold the retina in place (a pneumatic retinopexy), and sometimes a silicone buckle (called a scleral buckle) is sewn around the outside of the eye to keep the retina in place.
retina specialist. This is an ophthalmologist (MD) who goes on to sub-specialize in the treatment of retina problems. Retina doctors perform surgeries to correct retinal problems such as retinal detachments and membrane peels. They also treat wet macular degeneration, performing injection procedures and advanced retinal laser procedures. These doctors don't typically perform other eye services such as refraction for glasses, nor do they treat problems like glaucoma or cataracts.
retinitis pigmentosa. A genetic disorder of the retina that causes gradual vision loss. With retinitis pigmentosa (sometimes called RP) the photoreceptors (rods and cones of the retina) or their supporting cells gradually stop working, affecting vision. Some people develop visual loss in infancy while others have problems later in life. Often the rods (the photoreceptors responsible for peripheral and night vision) are involved such that the vision constricts inward making it hard to see in the periphery. Night vision is often severely diminished. There are over 80 different types of retinitis pigmentosa that have been discovered. Some are inherited from family, some occur by recessive mutations that only occur when two parents with the same gene defect have a child. Some
kinds of RP are sporadic with no family history at all. There have not been found to be any effective treatments for retinitis pigmentosa, though some retina doctors have tried high levels of vitamin A in the past. There is vigorous ongoing research looking for a cure for this disorder.
retinoscope. This is a hand-held tool the eye doctor uses to estimate refractive error such as nearsightedness, farsightedness, and astigmatism. This tool is challenging to learn and not as accurate as a true phoropter refraction. However, this is often the only method of determining a glasses prescription in a young child or non-verbal patient who can't give feedback while reading an eye chart. The retinoscope can also be used to determine a baseline prescription before refining the
glasses prescription using the phoropter.
retrobulbar block. This is a more intense way of numbing and paralyzing the eye before difficult eye surgery. Cataract surgery is normally performed under topical anesthesia - simple numbing drops placed on the eye while the patient remains awake. However, if we anticipate that a cataract surgery may take longer than usual (a dense cataract) or may require more manipulation (such as pupil stretching) than a "block" can be considered. With this technique, our patient is temporarily sedated by an anesthesiologist and put completely asleep for about 1-2 minutes. While asleep, the doctor (anesthesiologist or ophthalmologist) injects the retrobulbar numbing agent behind the eyeball itself. This completely numbs the eye and paralyzes the muscles that control eye movement and blinking. This makes the surgery much easier as there is no chance for pain or any unexpected eye movements during the procedure. The downside to a retrobulbar block is that it is
more invasive and may require clearance from a primary doctor first. If on blood thinners, these will need to be stopped ahead of time to decrease the chance of bleeding behind the eye from the injection. Finally, the temporary eyelid paralysis means the eye has a harder time closing immediately after surgery and may need to be patched shut overnight to keep the eye from drying out. This is inconvenient and may require a "safety stitch" during the surgery that extends operating time. In our patient population here in Daytona Beach, about one in twenty people require one of these blocks. In other parts of the world where everyone has a terrible, dense cataract (India for example) the majority of surgery is done with a retrobulbar block.
rewetting drops. Also known as artificial tears, these eye drops are designed to comfort and improve lubrication of the eyes. These can be bought over the counter and come with various trade names depending upon the manufacturer. Some popular brands are Soothe, Systane, Blink, and Refresh. Most of these drops contain the same ingredients, differing only by what preservative is used. All eye drops need preservatives (such as BAK) to keep them from getting colonized by bacteria floating in the air and on the eyelashes during use. Unfortunately, these preservatives can be harsh on the ocular surface, which is why we don't recommend using artificial tears more than 4-5 times a day. There are preservative free eye drops available that come in single use tear-off dispensers. These are great because they can be used frequently without irritating the eye. They can be expensive, however, and they are not as convenient to carry as you can't screw the caps back on. For most people, regular eye drops work fine with the generic drops working just as well as the fancier brand-name drops. If rewetting drops aren't working, then you can also try rewetting gels. These are like rewetting eye drops, but have a thicker consistency and last longer. The downside to the gels is that they make the vision a little blurry when first applied. For people with very dry eyes or exposure issues at night (for example, the eyelids aren't closing all the way when sleeping), rewetting ointments can be effective. These can be bought over the counter, have a consistency similar to Vaseline, and come in squeezable tubes. Ointments make the vision quite blurry so they are best used at bedtime. Popular brands of ointment include Genteel Gel and Refresh PM (the generic alternatives are just as effective).
rewetting gels. These are a type of rewetting drop that have a thicker consistency, similar to shampoo or pancake syrup (but not sticky, obviously). This thickness keeps the drop from evaporating as quickly so that it lasts longer and gives more relief with dry eye. The downside to these gels, however, is that they make the vision a little blurry when first put in. For most people, the additional lubrication is worth the temporary blurriness. Popular brands include Refresh Liquigel and GenTeal gel, but the generics are just as effective. You can find gel drops at the store mixed in with the regular rewetting drops. If the box has "gel" written in its name, you've found the right stuff.
rewetting ointments. These are thick ointments used for extreme dry eye. As rewetting ointments come in tubes they are challenging to put in the eye and the ointment causes significant blurriness to the vision. As such, they are typically reserved for people with extremely dry corneas that aren't adequately covered with traditional rewetting drops and rewetting gels. Some people have eye exposure problems at night. Their eyelids may not close completely while sleeping, which causes a rough or dry spot. The use of oxygen or sleep apnea machines can exacerbate this. In these cases, a rewetting ointment at bedtime will keep the eye lubricated all night long and hopefully make the eyes feel better the next day. To apply, we have our patient pull the lower eyelid down and apply a small amount of ointment (about the size of a grain of rice) to the inside of the eyelid. Then, blink a few times and the vision should get blurry as the ointment spreads over the surface of the eye. It does not take much ointment to lubricate the eye. If you have a difficult time applying an ointment, you may need help from family members. Rewetting ointments are available over the counter without the need for a prescription. They are located in the same section as the other artificial tears. Popular brands of rewetting ointments include Refresh PM and GenTeal Gel.
RK. This is a surgical procedure where a diamond knife is used to create radial cuts in the cornea. This changes the shape of the ocular surface and can help eliminate nearsightedness. See radial keratotomy for more information on this older refractive surgery.
rod. A type of photoreceptor inside the retina that senses light. Rods are very sensitive and give the eye excellent night vision. Rods can only see in "black and white" in contrast to cones, which are the photoreceptor cells that detect color.