Ophthalmic Pathology Case Studies


CASE 8: Diabetic Retinopathy


Clinical History:

A 62-year-old impoverished man living on a subsistance income has never received regular health care. He participates in a health screening program conducted by medical students and is found to have a random serum glucose of 181 mg/dL. On followup of this, his hemoglobin A1C is 10.3%. Based upon these findings, he is referred for vision testing.

Funduscopic Pathology:

Image 8.1 demonstrates a diabetic background retinopathy with extensive hard exudates as a result of microangiopathy that is associated with edema and retinal exudates that are "soft" microinfarcts or "hard" yellowish waxy exudates which are deposits of plasma proteins and lipids. The hard exudates are more a feature of older persons with type II diabetes mellitus. Also with background retinopathy leakage from small vessels leads to edema and swelling. If swelling occurs in the area of central vision (macula) then decreased visual acuity is marked.

Image 8.2 demonstrates a diabetic proliferative retinopathy with neovascularization characterized by a proliferation of small vessels near the optic disk. These delicate new vessels grow toward the vitreous humor. They are prone to bleed, producing vitreal hemorrhages that obscure vision. A proliferation of fibrovascular and glial tissue ensues, and when this contracts, there is a risk for retinal detachment. Proliferative retinopathy is less common but more severe than background retinopathy.

Questions:

  1. What is the diagnosis?

    2. This is diabetic retinopathy.

  2. What is the pathogenesis?

    3. Diabetes mellitus can damage the eye in several ways. The cells of the retina do not need insulin for glucose uptake and, as a result, hyperglycemia leads to increased intracellular glucose that is shunted into the the sorbitol pathway, leading to osmotic injury from accumulation of sorbitol. They retina can also be damaged by the microangiopathy of diabetes mellitus. In addition to retinopathy, persons with diabetes mellitus are more prone to cataracts and glaucoma.

  3. What is the prognosis?

    4. Early diagnosis and treatment of diabetes mellitus to control hyperglycemia can help to prevent complications. Retinopathy may take 20 to 20 years to develop. Laser therapy (photocoagulation) of neovascularization may help.