IOWA RETINA CONSULTANTS
We provide this glossary as a service to our patients. Please feel free to browse the alphabetical listing of eye-related terms for detailed definitions that will help you to better understand what we discussed in the office.
Age-related macular degeneration:
Deterioration of the tissues beneath the central part of the retina (the macula) that is usually found in people over 55 years of age. There are two main forms: 1) "dry" and 2) "wet". The "dry" form is more common and usually causes less visual loss than the "wet" form. The "dry" and "wet" types are subsets of the same disease. It always begins "dry" and sometimes progresses to become "wet". As the tissues beneath the retina degenerate, the retina no longer functions normally and the central vision becomes blurred. There is currently no treatment available for the "dry" form, apart from vitamin supplements, which are intended to stabilize the vision. The "wet" form causes abnormal blood vessels to grow beneath the retina. These vessels can bleed and leak fluid under the retina and eventually form a scar, resulting in severe visual loss. The "wet" type is most often treated with injections of medication into the eye, such as Avastin or Lucentis. Many potential new treatments for both the "dry" and "wet" types are under development. To learn more, click here.
A "visual prosthesis" that uses
A blood vessel that carries blood to a tissue. For example, a retinal artery carries blood to the retina. The blood supplies the retina with oxygen, which is necessary for normal retinal function.
A medication that is injected into the vitreous of the eye for treatment of a number of disorders, including “wet” macular degeneration, retinal swelling and abnormal blood vessel growth due to diabetic retinopathy, and blockages of retinal veins. Avastin was developed and FDA-approved for the treatment of metastatic colon cancer but is used very frequently in the treatment of eye diseases. It is usually injected about every six weeks when treatment is initiated, and the interval between injections is often lengthened gradually. Because the effect of Avastin declines over time, it often has to be injected indefinitely in order to maintain its beneficial effect on the vision. To learn more, click here.
Branch retinal artery occlusion:
A blockage in an artery that supplies blood to a portion of the retina. This blockage stops blood flow, preventing the supply of oxygen to part of the retina. As a result, the portion of the retina deprived of oxygen ceases to function. The patient often notices a dark area, usually above or below the center of the vision. Younger or older patients can be affected. This disorder can be caused by a small piece of clot that travels from the heart or an artery in the neck to the retina. It can also be caused by a number of other conditions. Patients with a branch retinal artery occlusion, whether younger or older, usually undergo a series of tests to search for the underlying cause. If such an underlying condition is identified, it can be treated in conjunction with the primary care physician. To learn more, click here.
Branch retinal vein occlusion:
A blockage in a vein that drains blood from one portion of the retina. The pressure in the occluded vein causes blood and fluid to leak into the retina. The central retina sometimes swells, much like a sponge soaking up water, causing blurred vision. This sort of retinal swelling is known as "macular edema". In more severe occlusions, abnormal blood vessels can grow on the surface of the retina. Such abnormal vessel growth is known as "neovascularization". Laser treatment is usually recommended for macular edema and for neovascularization. Medications such as Avastin, Lucentis and triamcinolone can be injected into the eye to reduce macular edema. Laser treatment and intraocular injections are sometimes combined in the treatment of macular edema. To learn more, click here.
Cloudiness of the lens. The eye is similar to a camera, with a lens that focuses light on the retina much as the lens in a camera focuses light on the film. When the lens becomes cloudy, the vision worsens, just as a camera would not take good pictures with a dirty lens. A cataract can be removed surgically and replaced by a clear, man-made lens implant. The lens implant is needed to do the focusing.
Central retinal artery occlusion:
A blockage of the central, or main, artery that supplies blood to the retina. It usually affects older people. The patient typically notices the sudden onset of severe visual loss in one eye. This disorder can be caused by a small piece of clot that travels from the heart or an artery in the neck to the retina. It can also be caused by a number of other conditions. Patients usually undergo a series of tests to search for the underlying cause. If such an underlying condition is identified, it can be treated in conjunction with the primary care physician. Rarely, abnormal blood vessels grow on the retinal surface or in the front portion of the eye months after a central retinal artery occlusion. Laser treatment and/or intraocular injections can be performed to control this abnormal blood vessel growth. To learn more, click here.
Central retinal vein occlusion:
A blockage in the central, or main, vein that drains blood from the retina. The pressure increases in all retinal veins, causing leakage of blood and fluid into the retina. The central retina often becomes swollen, causing blurred vision. Such swelling is known as "macular edema". Medications such as Avastin, Lucentis and triamcinolone can be injected into the eye to reduce the macular edema. In severe occlusions, abnormal blood vessels sometimes grow in the front part of the eye and can cause high pressure inside the eye, leading to severe pain and visual loss. Laser treatment and injections of medications such as Avastin and Lucentis can be done to reduce the abnormal blood vessel growth in the front part of the eye and can sometimes prevent the eye pressure from increasing. To learn more, click here.
Central serous chorioretinopathy (CSC):
A disorder of the tissues beneath the retina that causes accumulation of fluid under the central retina. It can cause blurring and distortion of the vision, in addition to abnormalities in the size and color of images. Patients are usually male, in their 30's or 40's, although women and older people can occasionally be affected. The vision usually improves without treatment, but the disease often recurs. Laser treatment or photodynamic therapy can be performed in selected cases when the fluid behind the retina fails to resolve or when the patient needs to hasten visual improvement in order to return to work. Environmental factors thought to cause this disorder include steroid medications (e.g., prednisone), taken by mouth, in inhalers, in nasal sprays, in skin cream or even injected into a knee or into the spine; ephedrine; sleep apnea; and irritation of the stomach caused by H. pylori. To learn more, click here.
The thin, transparent, skin-like covering over the white of the eye (the sclera). It contains blood vessels that are more easily visible when the eye is "blood-shot". In retina surgery, small incisions are sometimes made in the conjunctiva at the beginning of the procedure and stitches are sometimes placed in the conjunctiva at the end. These stitches dissolve over a few weeks.
The clear covering on the front of the eye. The cornea is comparable to the crystal on a watch. Occasionally, during retina surgery, the surface of the cornea is removed so that the surgeon can see more clearly inside the eye. The defect in the corneal surface can cause a scratchy feeling like there is sand in the eye. Fortunately, defects in the corneal surface usually heal, and the scratchy feeling resolves, within a few days after surgery.
Cystoid macular edema:
Swelling in the central retina. It can be caused by a variety of conditions but is most commonly caused by cataract surgery. It can be treated with eye drops, injections around or into the eye, and, in some cases, vitrectomy surgery. To learn more, click here.
A retinal disorder caused by diabetes mellitus (sometimes known as "sugar diabetes"). In its earliest stages, it does not cause symptoms. However, as it worsens, it can cause a variety of problems, including swelling of the retina, growth of abnormal blood vessels, bleeding inside the eye, and even retinal detachment. All of these complications can cause severe visual loss. Treatments for diabetic retinopathy include laser, intraocular injections and vitrectomy surgery. To learn more, click here.
A severe infection inside the eye. It can be caused by eye surgery, severe injuries or infections elsewhere in the body. Symptoms include severe pain and visual loss. Treatment includes injection of antibiotics inside the eye, and, in the most severe cases, vitrectomy surgery. To learn more, click here.
A thin membrane on the surface of the retina. An epiretinal membrane resembles a sheet of cellophane. It can contract and distort the retina, causing distortion and blurring of the vision. An epiretinal membrane can be removed by vitrectomy surgery, which often results in improvement of the vision. Another term to describe an epiretinal membrane is "macular pucker". To learn more, click here.
A medication for wet age-related macular degeneration and central retinal vein occlusion. Like Avastin and Lucentis, Eylea is injected into the eye. Also like Avastin and Lucentis, Eylea inhibits "VEGF", a substance that causes growth of abnormal blood vessels behind the retina. However, it uses a different mechanism to inhibit VEGF. The duration of Eylea's action is longer; after three consecutive monthly injections, it can then be injected every two months. Eylea seems to be at least as effective as Lucentis in improving and maintaining vision in patients with wet macular degeneration, and it has been proven to be quite effective for central retinal vein occlusion. Doctors might be able to lengthen the interval between Eylea injections beyond two months, and possibly longer than we are able to lengthen the interval between Avastin or Lucentis. This would reduce the burden of treatment on both the patient and on the doctor. To learn more, click here.
Images (usually dots or irregular shapes) that seem to "swim" as the eye moves. Floaters can be a symptom of a more serious eye problem, but they are usually harmless. They are often due to the separation of the vitreous from the retina, which usually does not cause any damage to the eye. If there is no other eye problem causing the floaters, no treatment is necessary. Rarely, floaters can be extremely bothersome. If they are so severe that they interfere with activities of daily living, vitrectomy surgery can be done. Vitrectomy, like any surgical procedure, involves risk, so it is reserved for those rare cases when the patient is extremely bothered by the floaters. To learn more about floaters, click here.
A test for evaluating abnormalities in, or beneath, the retina. A dye called fluorescein, is injected into a vein in the arm. The dye travels through the circulation to the eye within seconds. Numerous photographs are taken of the retina as the dye circulates through the blood vessels in the eye. Fluorescein angiography is used to diagnose a wide variety of disorders. It takes approximately 15 minutes and is done in the doctor's office. The skin and urine can change color for several hours after the test. Fluorescein angiography is a very safe test, but on rare occasions, patients experience nausea or an allergic reaction to the dye (itching, rash, hives, or even shortness of breath) during the test. Patients should avoid having blood drawn for laboratory tests within 24 hours of a fluorescein angiogram, as the fluorescein can interfere with blood tests.
The very most central part of the retina, responsible for detailed vision. The fovea is in the very center of the macula, which is a broader area in the central retina.
Damage to the optic nerve, usually due to increased pressure inside the eye. Glaucoma is typically painless and often progresses very slowly and does not cause symptoms until late in the disease. It causes loss of the peripheral vision first and only causes central visual loss when it is very advanced. Occasionally, glaucoma is caused by growth of abnormal blood vessels in the front portion of the eye where fluid normally drains from the eye. This type of glaucoma can cause rapid, extreme elevation of the eye pressure, resulting in severe pain and sometimes causing severe visual loss.
The "colored" portion of the eye. The eye color depends on the amount of pigment in the iris. Eyes with less pigment in the iris are blue, those with more pigment in the iris are brown, etc. The iris contains tiny muscles that change the size of the pupil depending on the level of light (in bright light, the pupil is smaller; in darkness, the pupil is larger). When we administer dilating drops in the office, the iris muscles react in a way that enlarges the pupil. The pupil is the "window" to the eye, so enlarging the pupil with dilating drops allows us to see inside the eye and examine the retina more easily.
A medication for treatment of symptomatic vitreomacular adhesion. Jetrea separates the vitreous gel from the macula by dissolving the connections between the two. When the virtreous is abnormally adherent to the macula, it can exert traction on the macula and cause it to swell. As a result, the vision worsens. Macular holes typically result from abnormal adherence of the vitreous to the macula and can be treated with Jetrea, as well, avoiding the risk and expense of vitrectomy. However, the success rate for Jetrea in closing macular holes is significantly less than for vitrectomy.
A device that creates a very focused beam of light. Lasers are used for a variety of reasons in several areas of medicine. They are also used in several different ways for treatment of eye disease. Retina specialists use lasers for a variety of disorders, including diabetic retinopathy, age-related macular degeneration, retinal tears, and retinal vein occlusions, among others. To learn more, click here.
A part of the eye that focuses light. The lens of the eye is similar to the lens in a camera. It focuses light on the retina just like the lens of a camera focuses light on the film. The lens is usually clear at the time of birth and slowly becomes less clear throughout life. A cloudy lens is known as a cataract. Cataracts are almost never harmful to the eye. Except for very rare occasions, they only need to be removed when they are reducing the vision to a level that is bothersome to the patient.
A medication that is injected into the vitreous of the eye for treatment of a number of disorders, including “wet” macular degeneration, retinal swelling and growth of abnormal blood vessels. Lucentis was developed and FDA-approved initially for treatment of “wet” macular degeneration but has also recently been FDA-approved for treatment of branch retinal vein occlusions and central retinal vein occlusions. To learn more, click here.
The central portion of the retina. The macula contains the fovea, which is a focal point in the very center of the macula. It is responsible for detailed vision. As its name implies, the macula is affected by macular degeneration.
See “age-related macular degeneration”. To learn more, click here.
Swelling of the central retina, which causes blurred vision. It can be caused by a variety of disorders, and its treatment depends on the underlying condition. Possible treatments include laser, eye drops, injections around the eye, injections into the eye, and vitrectomy surgery. Macular edema is most often caused by cataract surgery (cystoid macular edema), diabetic retinopathy and retinal vein occlusions.
A hole in the central portion of the retina which causes worsening of the central vision. Vitrectomy surgery can be performed to repair a macular hole and improve the vision. To learn more, click here.
The growth of abnormal blood vessels. This can occur on the surface of the retina (as in diabetic retinopathy), beneath the retina (as in the "wet" form of age-related macular degeneration), and in the front part of the eye (as in severe diabetic retinopathy and some retinal vein occlusions). Depending on the type of neovascularization, various types of laser treatment and injection of medication into the eye can be used to control the abnormal blood vessel growth.
Ocular histoplasmosis syndrome:
A retinal disorder caused by an inhaled fungus known as Histoplasma capsulatum. It is most common in the Ohio and Mississippi River valleys. When inhaled, the fungus causes a flu-like syndrome that resolves on its own. The infection can leave behind tiny scars behind the retina. These scars often do not cause any symptoms. However, if a scar occurs near the central retina, visual loss might result. Sometimes, abnormal vessels grow beneath the retina, next to a scar. These vessels can bleed and leak fluid under the retina, resulting in a larger scar and visual loss. Treatment options for these abnormal vessels include injections into the eye, laser, and vitrectomy surgery. To learn more, click here.
Photodynamic therapy (PDT):
A treatment for choroidal neovascularization (growth of abnormal blood vessels behind the retina). A photosensitive dye is injected into a vein in an arm. The dye collects in the abnormal blood vessels behind the retina. A low-intensity laser is then focused on the area of abnormal blood vessels. The laser activates the dye, which damages the abnormal vessels, causing them to close. The desired effect of the procedure is to eliminate fluid and blood from behind the retina. PDT is intended mainly to prevent further loss of vision, although a minority of treated patients do experience improvement. In most cases, PDT needs to be repeated a few times to achieve the desired effect, but it is not typically performed less frequently than every three months. Since the dye is extremely photosensitive, exposure to sunlight shortly following treatment can cause severe skin burns. Therefore, patients are asked to avoid sunlight for 3 days after the procedure. PDT has been largely replaced by medications injected into the eye, such as Avastin, Lucentis and Eyelea.
A procedure for repairing a retinal detachment. It can be performed in the office instead of the operating room. The retinal tear is typically treated with cryotherapy (freezing treatment) and a gas bubble is injected into the eye. Only certain types of retinal detachments can be treated with pneumatic retinopexy, so not every patient with a retinal detachment is an ideal candidate for this method. To learn more, click here.
Posterior vitreous detachment (PVD):
Separation of the vitreous from the retina. This occurs in most people at some point in life and usually does not cause any problems, although it can cause bothersome floaters and sometimes causes flashes of light. Occasionally, a tear can develop in the retina as the vitreous separates from it. A retinal tear can then cause a retinal detachment. As long as no retinal tear or detachment develops, no treatment is necessary for PVD. To learn more about PVD, click here.
Proliferative vitreoretinopathy (PVR):
The development of scar tissue on the surface of the retina following a retinal detachment. PVR can pull on the retina, causing it to become detached again. It can be treated with vitrectomy surgery, but it often causes severe visual loss. To learn more, click here.
The "hole" in the iris. The pupil is nothing but a circular space in the center of the iris. Its size changes due to contraction and relaxation of the muscles in the iris. The pupil is dilated for examination of the retina. Dilation of the pupil, which is accomplished with special eye drops, is like opening a window on the eye so that the doctor can see well enough into the back part of the eye to thoroughly examine the retina. Without the dilating drops, the retina cannot be adequately examined. Typical dilating drops keep the pupil dilated for approximately four hours.
A thin, nearly transparent membrane that lines the inner wall of the back portion of the eye, much as wallpaper lines a wall. The retina functions like film in a camera; it creates images and sends them to the brain to be interpreted as vision.
Separation of the retina from the inner wall of the eye. This usually occurs when a tear develops in the retina. Vitreous fluid passes through the tear and migrates beneath the retina, separating the retina from the inner wall of the eye. The retina must be attached to the eye wall in order to function properly. If untreated, most retinal detachments will eventually result in total blindness. To learn more, click here.
A retinal defect that usually results from the separation of the vitreous from the retina. Common symptoms include flashes of light and/or new floaters. A retinal tear can lead to retinal detachment and loss of vision, so anybody with symptoms of retinal tear should undergo evaluation. Laser or cryotherapy can be used to treat a retinal tear and prevent a retinal detachment. To learn more, click here.
A disease that affects the pigmented layer beneath the retina known as the retinal pigment epithelium (RPE). The RPE nourishes the retina and is necessary for normal retinal function. In retinitis pigmentosa, the RPE is unhealthy, so the retina does not work correctly. The peripheral vision is often affected first, followed by the central vision. Consequently, patients with retinitis pigmentosa often describe "tunnel vision". Severe visual loss can result. Treatment is limited, but vitamin A supplementation has been suggested. Extensive research is underway to develop "artificial vision" for patients with severe visual loss due to retinitis pigmentosa and other diseases.
Retinopathy of prematurity (ROP):
An abnormality of the developing retinal blood vessels in premature newborns. When babies are born prematurely, the blood vessels in the retina, which have not yet finished growing, sometimes begin to grow abnormally. This abnormal growth of vessels can lead to a retinal detachment that can cause severe visual loss. If it is detected early, laser treatment can be given in an effort to stop the abnormal blood vessel growth. Avastin, which is injected into the eye, is being evaluated as a new treatment option for retinopathy of prematurity, and results are quite promising. Sometimes, the disease progresses despite treatment and surgery is required to re-attach the retina. In severe cases, surgery may not be able to prevent loss of vision. To learn more, click here.
A procedure for repairing a retinal detachment. It usually involves placing a soft silicone band around the eye to indent the eye wall. Additionally, retinal tears are treated with cryotherapy (freezing treatment). Sometimes, fluid is drained from beneath the retina and/or a gas bubble is injected into the eye to facilitate reattachment of the retina. To learn more, click here.
Symptomatic Vitreomacular Adhesion:
A disorder involving an abnormal adherence between the vitreous gel and the central retina (macula). The vitreous exerts traction on the macula and often causes it to swell, resulting in visual loss. Macular holes develop as a result of abnormal adherence between the vitreous and macula, as well. Symptomatic vitreomacular adhesion can be treated with vitrectomy surgery, in which the adhesion is relieved mechanically by removing the vitreous gel. It can also be treated less invasively by injecting Jetrea into the vitreous. Jetrea dissolves the connections between the vireous and the macula and can be injected in the office, avoiding the risk an expense of vitrectomy.
Inflammation inside the eye. Uveitis can be related to an underlying disease, or it may be unrelated to any underlying problem. Blood tests, x-rays, etc., are often performed when uveitis is diagnosed, in an attempt to identify a systemic disease that might be related to the uveitis. These tests often fail to diagnose an underlying disorder, in which case the uveitis is considered "idiopathic" (without an identifiable cause). Depending on the location of the inflammation, uveitis can cause a variety of symptoms, including pain, redness, sensitivity to light, floaters, and decreased vision. Depending on the type of uveitis, it can be treated with anti-inflammatory drops, injections into or around the eye, pills, or surgery to implant a device inside the eye for long-term delivery of medication.
A blood vessel that drains blood from a tissue. For example, a retinal vein drains blood from the retina.
A surgical procedure to remove the vitreous. The vitreous is replaced by a saline solution during surgery, and the eye eventually replaces this solution with its own natural fluid. Sometimes, a vitrectomy is limited to removal of the vitreous. Usually, however, other maneuvers are performed inside the eye, depending on the reason for surgery. This procedure is performed in an operating room, usually under local anesthesia with intravenous sedation. To learn more, click here.
A clear gel that fills the back portion of the eye. The vitreous is removed and replace with a saline solution in vitrectomy surgery.
Bleeding into the vitreous. There are many causes of vitreous hemorrhage, but the most common cause is diabetic retinopathy, which can cause abnormal blood vessels to grow on the surface of the retina. These blood vessels can bleed into the vitreous. Vitreous hemorrhage causes decreased vision but can be removed surgically.