Central Retinal Vein Occlusion

Ischemic Central Retinal Vein Occlusion 

  • CRVO is the second most common retinal vascular disorder.
  • Patients are usually 50 years or older, but it can occur in younger patients.
  • Two clinical types: perfused (nonischemic) - 75%, and nonperfused (ischemic) - 25%.
  • The second eye can develop vein occlusion in 6-17% of cases.
  • Clinical features:
  • Symptoms: sudden, unilateral, painless visual loss that can range from better than 20/400 in non-ischemic eyes to 20/400 or worse in ischemic eyes

Fundoscopic findings:

  • Widespread retinal hemorrhages in all four quadrants, which vary in appearance from a small-scattered retinal hemorrhages to marked confluent hemorrhages
  • Marked dilated and tortuous retinal vessels 
  • Cotton-wool spots
  • Optic disc edema, macular edema, and retinal thickening 
  • Vitreous hemorrhages may be present 
  • A relative afferent pupillary defect (RAPD) can be present in ischemic CRVO
  • Collateral optociliary shunt vessels can develop
  • The fundoscopic findings in nonischemic CRVO are relatively milder than the changes seen in ischemic CRVO

Fluorescein angiography:

  • Delayed retinal vascular filling and marked increased retinal arteriovenous transit time
  • Marked hypofluorescence in all the four quadrants, consistent with the blocking effect of retinal hemorrhages
  • Capillary nonperfusion:
    • Ischemic CRVO is characterized by at least 10 disc areas of retinal capillary nonperfusion on the posterior pole
    • Nonischemic CRVO is characterized by less than 10 disc areas of retinal capillary nonperfusion
  • Late leakage
  • Associated conditions include: open-angle glaucoma or various systemic diseases such as diabetes mellitus, systemic hypertension or atherosclerotic cardiovascular diseases.

Prognosis:

  • Poor visual prognosis especially if involves a total area of at least 10 disc areas of retinal capillary nonperfusion and poor visual acuity at presentation.
  • Prognosis is better in the nonischemic CRVO especially when initial visual acuity is 20/40 or better or at least better than 20/200.
  • Two-thirds of eyes with ischemic CRVO may develop iris neovascularization or angle neovascularization and subsequent neovascular glaucoma. Retinal neovascularization is uncommon.
  • Nonischemic type may progress to ischemic CRVO in 5-22% of cases.
  • Permanent loss of central vision due to persistent macular edema.

Management:

  • Ocular work-up: best-corrected visual acuity, intraocular pressure, slit lamp biomicroscopy, gonioscopy and dilated fundus examination.
  • Monthly visits.
  • Treatment of associated systemic medical condition.
  • Panretinal laser photocoagulation is indicated if neovascularization develops.