BASICS
DESCRIPTION
Proliferative diabetic retinopathy (PDR) is characterized by the growth of fibrovascular tissue due to chronic, poorly controlled diabetes. PDR includes preretinal neovascularization, vitreous hemorrhage, traction retinal detachment, and secondary rhegmatogenous retinal detachment.
EPIDEMIOLOGY
Incidence
About 50% of patients with PDR will progress to legal blindness without treatment (1)[A].
Prevalence
Overall, 5% of patients with diabetes have PDR. Approximately 29% of patients who have had type 1 diabetes for greater than 15 years have PDR, compared with 16% of patients with type 2 diabetes for a similar duration.
RISK FACTORS
• Longer duration of diabetes
• Poor glycemic control
• Hypertension
• Pregnancy
GENERAL PREVENTION
• Optimizing blood pressure and blood glucose levels
• Routine eye exams and timely laser treatment
PATHOPHYSIOLOGY
• Accumulated capillary damage including endothelial proliferation, loss of pericytes, and capillary closure leading to retinal ischemia
• Local vascular and fibrovascular proliferation mediated by growth factors (e.g., vascular endothelial growth factor)
COMMONLY ASSOCIATED CONDITIONS
• Diabetic nephropathy and neuropathy
• Cardiovascular disease
• Macular edema and ischemia
DIAGNOSIS
HISTORY
• Determine onset of diabetes, duration and degree of glycemic control
• History of hypertension
• Previous laser treatment
• Pregnancy status
• Symptoms:
– Acute vision loss preceded by extensive floaters suggests vitreous hemorrhage or retinal detachment.
– Pain and redness of the eye may be due to neovascular glaucoma.
– Gradual loss of vision with macular ischemia, edema, or tractional retinal detachment
PHYSICAL EXAM
• Anterior segment exam: iris or angle neovascularization, hyphema, posterior synechiae
• Elevated intraocular pressure
• Posterior exam: vitreous hemorrhage, neovascularization of the disc (fibrous proliferation typically arising from optic disc and extending along major retinal vessels), and neovascularization elsewhere, both grow from the retinal surface into the vitreous and can lead to vitreous hemorrhage and/or tractional retinal detachments.
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• HbA1c, CBC, blood pressure
• Consider Hgb electrophoresis
• Carotid ultrasound
• Pregnancy test
Imaging
• Fluorescein angiography identifies areas of nonperfusion and neovascularization.
• Optical coherence tomography can assess macular edema.
• Ultrasound if vitreous hemorrhage
DIFFERENTIAL DIAGNOSIS
• Sickle cell retinopathy
• Ocular ischemia (carotid stenosis)
• Radiation retinopathy
• Retinal vein occlusion
• Hypertensive retinopathy
• Coats disease
• Occlusive vasculitis
• Talc retinopathy
TREATMENT
MEDICATION
• Consider antivascular endothelial growth factor medications (bevacizumab, ranibizumab) for control of neovascularization (2)[C].
• Topical glaucoma drops or oral acetazolamide to control eye pressure
ADDITIONAL TREATMENT
General Measures
Laser Photocoagulation
• Pan-retinal photocoagulation (PRP) if high-risk characteristics are present:
• Neovascularization associated with vitreous or preretinal hemorrhage or disc neovascularization larger than one-third disc area are high-risk characteristics and these patients should have PRP (3)[A].
SURGERY/OTHER PROCEDURES
Consider vitrectomy for nonclearing vitreous hemorrhage (>3 months duration), and tractional or rhegmatogenous retinal detachment or dense premacular hemorrhage.
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patients require very close monitoring until the disease is brought under control.
PATIENT MONITORING
Every 3 months until the disease is stable
PATIENT EDUCATION
Glycemic control. Exercise, weight management, blood pressure control, and close monitoring by internist/endocrinologist
PROGNOSIS
• Improved prognosis with early detection and treatment
• PRP reduces risk of severe vision loss by 50%.
• Macular detachments or severe macular ischemia leads to severe vision loss.
COMPLICATIONS
Retinal detachment, retinal ischemia, neovascular glaucoma
REFERENCES
1. Diabetic Retinopathy Study Research Group. Photocoagulation treatment of proliferative diabetic retinopathy. Ophthalmology 1978;85:82–106. [A]
2. Avery RL, Pearlman J, Pieramici DJ, et al. Intravitreal bevacizumab (Avastin) in the treatment of proliferative diabetic retinopathy. Ophthalmology 2006;10:1695–1705. [C]
3. Early Treatment Diabetic Study Group. Early Photocoagulation for diabetic retinopathy report 9. Ophthalmology 1991;98:766–785. [A]
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