The Retina

The M.D.s at Sierra Eye Associates are trained in recognizing and treating patients with Diabetic Retinopathy and Macular Degeneration. We have three fellowship trained vitreo-retinal specialist, Dr’s Khanani, Durant and Cecchi. We treat all aspects of retinal diseases including diabetic retinopathy, macular degeneration, retinal detachment, macular holes, macular puckers, uveitis and pediatric retinal surgery. We offer all current treatments for vitreous diseases including intravitreal injection of Lucentis, Avastin, as well as small gauge, suture less retina surgery under local anesthesia. Our office also provides the most advanced imaging equipment including the Heidelberg Spectralis OCT.

DIABETIC RETINOPATHY

diaretDiabetes mellitus is a condition that can have an effect on the small blood vessels of the body. One location of such small blood vessels is the retina in the eye. When the retinal blood vessels are affected, this is a condition called diabetic retinopathy.

Diabetic retinopathy development increases with the duration of the diabetes. It is unusual to see clinical signs of diabetic retinopathy prior to ten years after the onset of the disease. Diabetic retinopathy can progress with time, and has become the leading cause of legal blindness in working-aged adults. Our knowledge of treatment of diabetic retinopathy has increased over the last several years and blindness due to diabetes is becoming less frequent. In addition to treatment of the retina directly, recent studies have shown that strict blood sugar control can decrease the onset and progression of diabetic retinopathy.

Clinically, diabetic retinopathy is divided into two broad categories, non-proliferative and proliferative retinopathy.

Non-proliferative diabetic retinopathy is caused by damage to the walls of the normally present retinal blood vessels. The damage to the walls of the vessels results in leakage of blood and fluid from the small blood vessels. This leakage can result in swelling of the retina, like a sponge taking up water. If the swelling involves the macula (center of the vision) then vision is affected. Fatty material (lipid) can leak from blood vessels and can result in more permanent loss of vision. More severe damage to the retinal blood vessels can result in closure of vessels and decreased blood flow to areas of the retina. If this loss of blood flow and nutrition involves the center of the vision, significant loss of vision can result.

Proliferative diabetic retinopathy results when there is the development of abnormal (“neovascular”) blood vessels in addition to the normally present retinal blood vessels. Neovascularization results from the vascular damage resulting in lack of blood flow and nutrition to large areas of the retina. The retina becomes “starved” for oxygen, and a chemical signal is sent from damaged retina to induce the body to grow new blood vessels. This is the body’s response to provide more oxygen to those areas, but the new blood vessels are fragile and grow from the surface of the retina into the vitreous “jelly” in the center of the eye. The movement of the vitreous “jelly” and the new blood vessels can result in rupture of the fragile vessels, resulting in bleeding into the center of the eye. With time, the abnormal blood vessels can scar over, contract, and pull on the surface of the retina. This pulling can cause the retina to come away from the back of the eye (retinal detachment) and can result in permanent blindness.

Treatment of diabetic retinopathy consists of in-office laser photocoagulation and/or a surgical procedure known as vitrectomy. We also offer all current treatments for diabetic retinopathy including intravitreal injection of Avastin, steroid, as well as small gauge, suture less retina surgery under local anesthesia.

Laser photocoagulation can be used to achieve one of two goals. Laser can either cauterize blood vessels that are leaking to stop leakage or it can destroy damaged retinal tissue by creating scarring.

In non-proliferative diabetic retinopathy, vision loss can be caused by leakage from retinal blood vessels. Laser is applied to the areas of leakage to try to decrease leakage and allow the body to reabsorb leaked material. The laser is often guided by a photograph test known as fluorescein angiography. This test is performed in the office by injecting an intravenous fluorescein dye while photos are taken of the dye circulation through the retina. The risk of significant visual loss can be reduced by the use of laser in non-proliferative diabetic retinopathy.

In proliferative diabetic retinopathy, new, abnormal, blood vessel growth develops due to damaged retina that sends out chemical signals. Laser in this situation is applied to try to ablate damaged retina by creating scarring. If damaged retina is destroyed, new blood vessel growth will regress. This ablation of damaged retina requires the application of many (often more than 1000) laser burns to the peripheral retina. This may be done in one or multiple sessions, and can be done with or without anesthetic injection around the eye.

Significant visual loss can be reduced by up to 66% with the use of laser in proliferative diabetic retinopathy. There can be side effects of this more intense laser treatment, such as decreased night vision, decreased peripheral vision, and blurring of central vision.

Vitrectomy surgery is indicated when there is bleeding into the center of the eye that persists and cannot be treated with laser. At times, scar tissue formation from abnormal blood vessel growth can cause pulling on the retina and retinal detachment. Vitrectomy surgery is microscopic surgery with small instrumentation that is used to remove vitreous, blood, and certain scar tissue. Damage that results in the need for vitrectomy surgery is often advanced, and the goals of surgery are often to regain ambulating vision, but not particularly reading vision.

In summary, vision can often be maintained in diabetes. Strict blood sugar control and regular examinations for early detection are critical elements in maintaining as much vision as possible. The incidence of diabetic retinopathy goes up after 10 years of diabetes, and the frequency of examination will be determined by your eye specialist. Very close monitoring of diabetic retinopathy is necessary during pregnancy, as progression can occur. If changes of diabetic retinopathy threaten visual loss, laser photocoagulation should be considered. We often can maintain vision at a certain level, but regaining vision lost is usually not possible.

Age Related Macular Degeneration (ARMD) is a disease that affects the retina of the eye. This condition is probably hereditary in nature, but the only known association is advancing age. The retina is the inner lining of the back of the eye, like the inside of the wall of a basketball. The retina works like film in a camera. The central part of the vision, that part used for reading, is served by a portion of the retina called the macula. This is the area involved in ARMD.

The earliest sign seen in ARMD is the presence of yellow deposits below the retina, called drusen. This indicates a “tendency” toward ARMD, but typically does not cause significant loss of vision. ARMD may progress in those eyes with drusen, and therefore regular observation for the signs of ARMD is indicated.

MACULAR DEGENERATION

maculardegARMD is clinically divided into two types. These vary in time course of vision loss, symptoms, and options for treatment.

Dry Macular Degeneration is a type where there is gradual degeneration of the cells associated with the central vision. The major symptom is usually gradual onset of increased difficulty with reading and central vision. This may occur over many years. Loss of vision can vary from mild to severe central vision loss. No specific treatment for this condition is known. There has been a lot of “talk” about the role of vitamins in ARMD, but scientific evidence is lacking. Those proponents of vitamins feel that vitamin use may help to keep the affected cells more healthy and slow down the degeneration of those cells.

Wet Macular Degeneration is a type where leakage develops under the macula. Leakage may be associated with abnormal blood vessels called Choroidal Neovascularization. If leakage is not associated with choroidal neovascularization, then typically a blister of fluid develops, and this may remain the same or slowly become larger. This can cause distortion and/or blurring of the central vision. If no choroidal neovascularization is present, then the situation is observed only, and the blister can collapse over time.

If choroidal neovascularization is present, the abnormal blood vessels are often fragile and leaky. This can result in fluid leakage or bleeding. Such changes often cause distortion, “missing areas” and blurring of the central vision. The onset of these changes can literally be over a matter of hours. We offer all current treatments for wet age related macular degeneration including intravitreal injection of Lucentis and Avastin.

Fluorescein Angiography is a test performed in the office to identify if macular degeneration is of the wet or dry type, and to determine if choroidal neovascularization is present. This involves injection of a fluorescein dye into a vein and taking pictures of the retina with a special fluorescein camera to track the flow of fluorescein through the blood vessels.

Management of patients with ARMD varies according to the type of ARMD, stage of the disease, and the treatment that may have been indicated. All patients with ARMD should check their own vision every day for any change such as decreased vision, new distortion or new missing areas. Patients are typically scheduled for regular follow-up visits to determine if there is progression, but since dry ARMD can change to wet ARMD at any time it is important that you let us know if there are new changes so we can evaluate you sooner than the scheduled follow-up visit.

ARMD is a disease that affects both eyes. One eye may have much more involvement than the other. In a patient who has had significant changes in one eye, the other eye is at somewhat more of a risk of having similar changes. Both eyes are evaluated at follow-up visits, and changes in either eye may be important.

One concern of many patients is the fear of total blindness. Fortunately, ARMD does not cause total blindness and even with total loss of central vision there is still usable peripheral vision.

 

Please call (775) 329-0286 if you would like to schedule an appointment.