The primary vein draining blood from all four quadrants of the retina can become blocked or occluded. Every heart beat forces more blood up to the eye.
Increased pressure in the small capillary vessels between the arteries and veins causes them to rupture. Blood and fluid generate retinal swelling and decreased vision.
What are the types of Central Retinal Vein Occlusions?
CRVOs are staged as either perfused (P-CRVO) or non-perfused (NP-CRVO). Eyes in the perfused (P) subset sustain minimal damage to the retinal capillaries. Vision is usually better than 20/200 and there is no pupil defect.
Eyes in the non-perfused (NP) subset are at increased risk for development of secondary complications including vitreous hemorrhage and a severe form of glaucoma. A significant percentage of eyes with P-CRVO may decompensate to the non-perfused type over time. This most likely follows a "second hit", or re-occlusion, of the central retinal vein.
What are the symptoms of a Central Retinal Vein Occlusion?
The main symptom is painless blurred vision. This occurs most commonly due to the excess fluid that leaks from damaged capillaries and collects in the macula.
Significant pain can occur if excessive eye pressure develops from a late complication called neovascular glaucoma.
How is Central Retinal Vein Occlusion treated?
The primary therapy for CRVO is now special medication administrated by intravitreal injection.
Laser surgery is very effective in reversing the growth of abnormal blood vessels that develop in response to vein retinal occlusions. Laser surgery does not remove existing vitreous hemorrhage, and blood may prohibit in-office treatment.
In some cases surgery requiring an operating room may be indicated. Laser is usually performed once vitreous blood is removed by vitrectomy.