Seventh characters have been added to subcategory H34.8, Other retinal vein occlusions, to designate the severity of the occlusion:
0, with macular edema
1, with retinal neovascularization
Retinal vein occlusion (RVO), blockage of the venous circulation that carries blood away from the retina, is one of the most common causes of vision loss. When the small veins of the retina are blocked, pressure builds in the capillaries, causing hemorrhage of fluid and blood.
Similar to a stroke, RVO may be caused by blockage, clotting, or hardening and narrowing of the arteries by chronic conditions such as atherosclerosis, glaucoma, diabetes mellitus, hypertension and macula edema. However, RVO may also result from disease of the wall of the vein or from external compression of the vein.
RVO is based on the area of occlusion. Narrowing may occur in the central retinal vein at the level of the optic nerve, known as central retinal vein occlusion (CRVO) or at the distal branch of the retinal vein, known as branch retinal vein occlusion (BRVO).
Severity of the RVO depends on location and the loss of blood flow. CRVO is sudden and ranges from mild blurring to severe vision loss. BRVO is more common than CRVO; there may be no symptoms.
Macular edema, swelling of the central portion of the retina, occurs in almost all cases of CRVO and in over half the cases of BRVO. Neovascularization occurs when new blood vessels develop in an attempt to continue to supply the retina with blood. These new blood vessels may hemorrhage and cause retinal detachment.The new seventh characters will provide important information to indicate there is macular edema or neovascularization requiring intervention such as intraocular anti-vascular endothelial growth factor drugs and corticosteroids. The seventh-character, “2” (stable), is assigned when the disease process is not active and there is no reason for treatment.