In the latest article in our Clinical Therapeutics review series, proliferative retinopathy develops in a 55-year-old man with type 2 diabetes. Panretinal photocoagulation, which causes reduced production of VEGF by destroying hypoxic retinal cells, is recommended. Diminished peripheral and night vision can occur.
Data from the Diabetic Retinopathy Study indicate that approximately half of all eyes with proliferative diabetic retinopathy, if left untreated, will have profound vision loss (less than 20/800 for at least 4 months); this represents a level of vision that interferes with the ability to ambulate.
• How common is retinopathy among patients with diabetes?
A pooled data analysis of several population-based studies estimated that approximately 40% of people with diabetes over the age of 40 have some retinopathy, including 8.2% with vision-threatening retinopathy (usually diabetic macular edema, but less frequently proliferative retinopathy).
• What is the efficacy of panretinal photocoagulation?
For patients with severe non-proliferative diabetic retinopathy, or early proliferative diabetic retinopathy in the Early Treatment Diabetic Retinopathy Study, panretinal photocoagulation — and vitrectomy when necessary — reduced the 5-year risk of severe vision loss from more than 50%, if left untreated, to approximately 4% of eyes and 1% of patients.
Figure 3. Indirect Laser Delivery System.
Morning Report Questions
Q: What adverse effects are associated with panretinal photocoagulation?
A: Because panretinal photocoagulation destroys viable retinal tissue, visual symptoms can occur related to loss of function of the retinal tissue where the burns are placed. These symptoms include peripheral visual field defects, reduced night vision, diminished color vision, and decreased contrast sensitivity. Other possible adverse effects include choroidal effusions or choroidal detachment (<1% of the time), which may cause transient myopia or increased intraocular pressure, and, most seriously (but very infrequently), complications from misdirected burns or excessively intense burns.
Q: What are the contraindications to proceeding with panretinal photocoagulation?
A: If macular edema is present and the proliferative retinopathy is less than “high-risk,” panretinal photocoagulation often may be delayed (though only for a few weeks or months) until after macular edema has been treated, since the panretinal treatment could worsen the macular edema. The use of antithrombotic agents, including aspirin, is not a contraindication to proceeding with treatment.