Leading signs of nonproliferative retinopathy include:

• Microaneurysms: appear as tiny red dots in the retina

• Venous beading: irregular constriction and dilation of the lumen of retinal venules
• Intraretinal microvascular abnormalities: shunt vessels, or enlarged hypercellular capillaries, adjacent to or surrounding areas of occluded capillaries within the retina

SCREENING GUIDELINES
If diabetes is diagnosed before age 30, annual eye exams starting five years after diagnosis (or at age 10 if diagnosis is made before age 5) are necessary. Earlier evaluation is not necessary because retinopathy does not occur before puberty and is rare before five years of duration of the disease.

For diabetics over age 30, annual eye exams starting at the time of diagnosis are necessary. This is because the condition has generally been present longer by the time of diagnosis. In fact, some already have macular edema and proliferative retinopatby at diagnosis.

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MANAGING DIABETIC RETINOPATHY
Diabetic retinopathy is the leading cause of new cases of legal blindness among working-age Americans. Because retinopathy is progressive, individuals with diabetes require careful monitoring by an ophthalmologist with more frequent examinations as the condition of the eye deteriorates.

In the earliest stages, diabetic retinopathy is indicated by increased retinal vascular permeability, which can lead to fluid accumulation in the retina. In the more advanced stages, new vessel proliferation, vitreous hemorrhage, retinal detachment, and neovascular glaucoma may develop.

Laser surgery is generally recommended for those with high-risk proliferative retinopathy with or without recent vitreous or preretinal hemorrhage; those with severe NPDR that progresses and approaches high-risk PDR; and those with clinically significant macular edema (CSME) at any stage of retinopathy.

Effective screening for diabetic retinopathy depends on retinal examination, which can save as much as $62 million in health costs each year. This requires a strong partnership between the primary care physician and the ophthalmologist. The goal for the primary care physician is to become familiar with the retinal complications of diabetes, the current techniques for dilated ophthalmoscopic examinations, and current recommendations for referring patients to an ophthalmologist.

ADVANCED RETINOPATHY
Severe nonproliferative retinopathy (formerly termed "preproliferative") is characterized by the presence of venous beading and dilation and/or significant areas of large retinal blot hemorrhages, multiple cotton wool spots and/or extensive intraretinal microvascular abnormalities. Between 10% and 50% of patients with preproliferative changes will develop proliferative diabetic retinopathy within one year. Therefore, these patients require especially close monitoring and should be reexamined within three to four months.

HIGH-RISK PROLIFERATIVE RETINOPATHY
High-risk characteristics for severe visual loss include NVD greater than 1/4 to 1/3 disc area and vitreous or preretinal hemorrhage associated with less extensive NVD or with NVE 1/2 disc area or more in size. Without intervention, 50% of patients with high-risk proliferative retinopathy will develop severe vision loss in five years. These patients usually require treatment without delay because of the strong likelihood of severe vision loss.

Treatment of neovascularization with high-risk characteristics is by scatter (panretinal) photocoagulation, in which 1,000 to 2,000 laser burns are applied in the mid-peripheral and peripheral portions of the retina, sparing the macula. Key studies have demonstrated the value of this technique in the regression of neovascularization and reduction of vision loss. Most patients respond well to photocoagulation surgery when it is carried out at the proper time. However, if proliferative rctinopathy is not detected until after a vitreous hemorrhage has developed, vitrectomy may be necessary. Retinal traction can be alleviated by surgical excision of fibrovascular tissue and a membrane peeling. To reduce the risk of further neovascular growth, ischemic retina can be treated with (endolaser) photocoagulation.

PROGRESSION OF DIABETIC RETINOPATHY

• NPDR (Non Proliferable Diabetic Retinopathy) occurs when retinal blood vessels leak, and leakage into the macula may cause reduced vision.
• PDR (Prolifcrative Diabetic Retinography) is a progressive retinal ischemia leading to neovascularization, fibrous proliferation, bleeding, traction retinal detachment, and blindness.
• Early NPDR shows retinal microaneurysms, hard exudates, and intraretinal hemorrhages either in isolation or in combination.
• Microaneurysms appear as tiny red dots in the retina.
• Hard exudates are a result of vascular leakage and consists of yellow lipid.
• Intraretinal hemorrhages appear as small red dots, blots or as large flame-shaped hemorrhages.
• Diabetic macula edema is related to the duration of diabetes -- 5% after five years of diagnosis and 15% after 15 years of diagnosis.

MACULAR EDEMA
The most common cause of vision impairment from diabetes, macular edema, can occur at any stage of retinopathy. The development of edematous thickening of the macula disturbs the architecture of the retina and leads to blurred vision. When macular edema involves the center of the macula, there is a 32% chance of moderate vision loss in three years without laser surgery. Focal laser treatment reduces this risk by more than 50%.

Focal laser photocoagulation targets laser burns at abnormal blood vessels in the macula in an attempt to reduce chronic leaking fluid. Fluorescein angiography is necessary prior to surgery to identify treatable lesions. The identification of diffuse rather than focal leakage on the fluorescein angiogram is an indication for grid laser photocoagulation, in which a grid pattern of burns is applied in the area of edema. Retreatment by laser may be necessary if mac-ular edema persists.

Because appropriate laser photo-coagulation substantially reduces the risk of vision loss, patients with clinically significant macnlar edema (CSME) should be considered for laser surgery. When edema inw~lving the center of the macnla is present in an eye that is approaching or has reached high-risk pro-liferative diabetic retinopathy, both panretinal and focal/grid photocoagula-tion should be considered.

OTHER ASPECTS OF DIABETIC CARE
There is increasing evidence of an association between good metabolic control and less severe retinopathy. Studies have demonstrated that intensive treatment of patients with diabetes to maintain blood glucose at near-normal levels reduces the development of retinopathy in patients with no retinopathy and slows progression of retinopathy in patients with early rctinopathy.

Studies also suggest that control of diastolic blood pressure may reduce the severity and progression of retinopathy. Maintaining optimal glycemic control and monitoring and treating other medical problems, such as systemic hypertension, renal disease, and elevated blood lipid levels, remain essential elements in controlling or preventing diabetic retinopathy.

Pregnant diabetics with retinopathy run the risk of progression of retinopathy during the pregnancy, so they need to be monitored at frequent intervals throughout the pregnancy. Women with gestational diabetes alone are not at risk for retinopathy.

In conclusion, early treatment and improved screenings will help prevent blindness. Since diabetes will increase as the percentage of aging Americans increases, screenings are a cost-effective way of reducing blindness.