- 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
- 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
- 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.
- 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.
- 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.