PRP Efficacy in Preventing Retinal Neovascularization in RVO
Dense peripheral panretinal photocoagulation (PRP) is highly effective for treating established retinal neovascularization in RVO, but prophylactic PRP does not reliably prevent neovascularization from developing in the first place. 1
Treatment Approach Based on RVO Type
Central Retinal Vein Occlusion (CRVO)
For patients who develop iris or retinal neovascularization following CRVO, dense peripheral PRP is the best treatment and should be applied promptly. 1 This approach:
- Decreases the risk of progression to iris neovascularization 1
- May prevent neovascular glaucoma 1
- Does not typically improve visual acuity but addresses the most vision-threatening complications 1
Prophylactic PRP in ischemic CRVO is NOT recommended because it does not reliably prevent neovascularization from developing. 2 The landmark Central Vein Occlusion Study (CVOS) demonstrated that:
- Prophylactic PRP did not significantly prevent development of iris or angle neovascularization when adjusted for baseline factors 2
- Prompt regression of neovascularization occurred in 56% of previously untreated eyes versus only 22% of eyes that received prophylactic treatment 2
- The recommended approach is careful observation with frequent follow-up (including undilated slit-lamp examination and gonioscopy) and prompt PRP only when neovascularization develops 2
Branch Retinal Vein Occlusion (BRVO)
Sectoral PRP to areas of retinal nonperfusion is recommended when neovascularization develops, particularly when complications such as vitreous hemorrhage or iris neovascularization occur. 1, 3
Role of Anti-VEGF as Adjunctive Therapy
Anti-VEGF agents should be used in an adjunctive manner when complete PRP is insufficient to control angiogenesis. 1, 4 This combination approach:
- Reduces the severity of anterior segment neovascularization 1
- Lowers the risk of ocular angiogenesis 1, 4
- Provides immediate benefit and may improve the ability to deliver complete laser treatment 4
Critical Monitoring Protocol
Monthly follow-up for 6 months is essential in eyes with CRVO, particularly ischemic CRVO, to detect neovascularization early. 3 Each visit must include:
- Undilated slit-lamp biomicroscopy with careful iris examination 1, 3
- Gonioscopy to detect angle neovascularization 1, 3
- Pupillary assessment for relative afferent pupillary defect 1
- Intraocular pressure measurement 1
- Stereoscopic examination of the posterior pole after dilation 1
Common Pitfalls to Avoid
Do not perform prophylactic PRP in ischemic CRVO expecting to prevent neovascularization—the evidence shows this is ineffective and may actually reduce the likelihood of regression when neovascularization does develop. 2 Instead, maintain vigilant monitoring and treat promptly when neovascularization appears.
Do not delay PRP once neovascularization is detected—prompt treatment results in better regression rates and prevents progression to neovascular glaucoma. 2
Do not rely on PRP alone if neovascularization persists or progresses—add anti-VEGF therapy as adjunctive treatment. 1, 4
Evidence Quality Note
The recommendation against prophylactic PRP is based on Level I evidence from the multicenter randomized CVOS trial, which specifically addressed this question. 2 The recommendation for treating established neovascularization with PRP is supported by multiple high-quality guidelines from the American Academy of Ophthalmology. 1