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Amsler Grid
An Amsler grid can help you detect changes in your vision.
 Click here for a printable copy
Anatomy
How the Eye Works
 The cornea, lens, and pupil allow light to pass through, and then the light passes through the vitreous cavity, which is filled with a clear, gel-like substance called vitreous or vitreous gel. The light that passes through is focused by the cornea and lens onto the retina, which acts like the film in a camera. The retina covers the back inside wall of the eye. In the camera analogy, the retina takes on the role of the film in the camera. After the light passes through the cornea and lens, it is focused. The focused light then hits the retina and a "picture" is taken. At this point, the picture or message is sent through the optic nerve. The optic nerve is behind the retina and sends these images to the brain and this is how we see.
The Retina
The retina consists of two parts: the macula and the peripheral retina. The macula, the center of the eye, is similar to a bull’s eye on a dartboard. The peripheral retina accounts for 95% of the retina and it allows you to see things to the side. The peripheral allows you to see "out of the corner of you eye", but it does not help you see images clearly. An example of the two parts of the retina working together would be seeing someone out of the corner of your eye. The peripheral retina will notice that someone is there but it cannot distinguish facial features or details. The macula will help you distinguish detail. The macula is 100 times more sensitive to detail than the peripheral retina. The macula may only account for 5% of the retina, but it performs a very vital function by allowing you to do things like read fine print, drive a car, and sew.
Vitreous
The vitreous is a clear, gel-like substance that fills the middle of the eye. The vitreous is similar to "egg-whites" inside an egg. When there is a problem with the vitreous, there is a good chance that there is also a problem with the retina because the two go hand-in-hand. The vitreous is most strongly attached to the front part of the retina. This area is called the vitreous base. The vitreous is also attached to the optic nerve.
Diagnosis
Age Related Macular Degeneration
Age-related macular degeneration (AMD) is the leading cause of severe vision loss in people older than 55 in the United States. AMD progressively impairs the quality of central vision, which results in decreased vision acuity, distortion or central vision, and black spots or blind spots, which are also referred to as scotomas. With AMD, there is a decrease in contrast sensitivity, which is the ability to contrast one object from another. There are two forms of AMD, wet and dry. The wet form is the more serious of the two forms of AMD. The wet form is also called the neovascular form because abnormal blood vessels grow and they can bleed and exude fluid. 10% of AMD is in the wet form, but this form is responsible for 90% of severe vision loss.
Proliferative Diabetic Reitinopathy
Proliferative Diabetic Retinopathy (PDR) occurs when abnormal blood vessels and scar tissue grow on the retina and attach firmly to the back of the vitreous. In turn, the vitreous pulls on the scar tissue, which can cause the retinal blood vessels to bleed into the vitreous cavity. This is referred to as a vitreous hemorrhage. The result of a vitreous hemorrhage is a blood filled vitreous, which can cause vision distortion.
Macular Edema
Macular Edema is the swelling of the macula. The edema is caused by fluid leaking from blood vessels. Central vision is affected. The macula is surrounded by many blood vessels, so anything affecting them, such as a medical condition affecting blood vessels elsewhere in the body or an abnormal condition originating in the eye, can cause Macular Edema. Diabetes, retinal blood vessel obstruction, eye inflammation, and AMD, have all been associated with Macular Edema.
Posterior Vitreous Detachment
As people age, the vitreous becomes less like a gel and more like a fluid. The liquefied vitreous then begins to move around in the vitreous cavity. When this happens, the vitreous begins to pull on the retina, which could cause the retina and optic nerve to detach. This results in Posterior Vitreous Detachment (PVD).
Flashers and Floaters
Flashers appear to be flashing lights in the patient’s field of vision. The flashes that the patient sees are the vitreous pulling on the retina. The brain interprets the pulling as a flashing of light, hence the name flashers. Floaters are tiny clumps of gel or cells that are floating in the vitreous. The floaters appear to be in front of the eye but in actuality they are inside the eye. The spots that you see are shadows that are created by floaters that are cast on the retina. The presence of these floaters should alert you to see a doctor, but it does not mean a retinal detachment exists. Once cleared by your doctor, you can learn to ignore or live with them. There is not a treatment for floaters unless they are disabling and prevent day-to-day activity and functioning. A vitrectomy can be done to remove them.
Retinal Detachment and Retinal Tear
A Retinal Detachment (RD) is the separation of the retina from the back wall of the eye. A retinal tear usually brings on a detachment. When a detachment occurs, the vitreous flows through the tear and thus separates the retina from the back of the eye. After the detachment, vision will be lost in that area. Tears occur when the vitreous pulls away from the retina where the retina is weak. Most tears are located in the periphery. In your peripheral vision, you may notice a gray area or a veil from one side of your eye. When a tear occurs, it will almost always be followed by a detachment if it is not promptly treated.
Vitreous Hemorrhage
When a retinal tear occurs near a retinal blood vessel, it could cause blood to enter the vitreous, thus causing a vitreous hemorrhage. A small bleed will create the image of walking through a swarm of flies or gnats in one’s vision. If the bleed is considered a large bleed, it will create the image of a swirling mass of black or red lines. An excessive amount of bleeding will reduce one’s vision significantly and could cause the patients vision to completely fade to black.
Surgeries
Scleral Buckle
The scleral buckle is a flexible band that is placed around the eye to counteract the pulling or tugging that has been created from a retinal tear or detachment. The scleral band holds retinal tear to settle the tear back into place so a successful surgery can be performed. This procedure is done in an operating room with the use of laser or cyroprobe. A cyroprobe is used to freeze the tear or detachment back into its proper position. The scleral band will remain in place indefinitely unless a major complication comes about, such as infection or irritation from the scleral band possible being too tight. After this procedure, the eye will take a slightly different shape and thus probably require new glasses because of a possible vision change.
Pneumatic Retinopexy
Using a needle, the surgeon injects a gas bubble inside the vitreous cavity of the eye. The bubble pushes the retinal tear against the back wall of the eye and the patient is asked to keep his or her head in a specific position (usually face-down), so the bubble will not come to rest against the lens of the eye. Failure to adhere to this position may cause cataract and high pressure during the days following surgery. The bubble will expand for several days and take 2-6 weeks to disappear. During this time, airplane travel and travel to high altitudes is prohibited because the pressure in the eye could increase, which could damage the eye. The chances of retinal re-attachment with this procedure are less, but other things are avoided such as, hospitalization, general anesthesia, and cutting out and fitting a scleral buckle. This procedure cannot be used for all re-attachments. Complications include cataract formation, glaucoma, gas getting under the retina, excessive scar tissue formation, and infection. These complications can lead to vision loss, but each is rare. The most common complication is new retinal tears or the retina becoming detached again. If this were to happen, the scleral buckle or vitrectomy would be performed to correct this problem. Cryotherapy and/or lasers treatment is performed to treat the retinal tear in this procedure as well.
Vitrectomy (Vitreous Surgery)
This procedure is used in the most complicated and severe retinal detachments. This procedure is used when the scleral buckle or pneumatic retinopexy cannot be used to help the patient. This surgery is performed in an Operating Room under general or local anesthesia. In this operation, the vitreous is removed. The vitreous is replaced with either a clear fluid that imitates the vitreous that is being removed, or a gas is used that will completely fill the eye. With time, the inserted fluid or gas is absorbed by the eye and the eye makes its own new fluid. The eye does not remake the vitreous gel. The lack of vitreous does not effect the functioning of the eye. The most common conditions that require this type of surgery are: retinal detachment, an eye that has had cataract surgery, vitreous hemorrhage w/ retinal detachment, proliferative vitreoretinopathy, diabetic retinopathy with vitreous hemorrhage and/or tractional retinal detachment, macular pucker, intraocular infection, endophthalmitis, trauma, intraocular foreign body, and macular hole. Various instruments can be used for this procedure, but they all perform the same function. That function is removing the vitreous gel and inserting new imitation filler. This filler can be air, gas, or silicone oil. After this filler is inserted a laser is used to form scars that will hold the retina in place. If air or gas is used it will naturally be replaced by fluid that is created with in the eye. If silicone oil is used it has to be removed at a later date. The surgery typically lasts between one and two hours but in some more severe cases it may take longer. A "scratchy" sensation may appear after the procedure but significant pain is unusual. If severe pain or discomfort comes after the procedure, consult your doctor immediately.
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Vitreo-Retinal Associates |
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Shreveport/Bossier City |
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Natchitoches |
(318) 222-8421/(800) 521-7218 |
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(800) 521-7218 |
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Ruston |
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Texarkana |
(800) 521-7218 |
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(800) 521-7218 |
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