CENTRAL RETINAL VEIN OCCLUSION (ISCHEMIC in the first picture, NON-ISCHEMIC in the second picture)
CRVO occurs due to the occlusion of the central retinal vein at or posterior to the lamina cribrosa. It causes painless unilateral loss of vision.
Pathogenesis : VIRCHOW’S TRIAD : Vessel damage, Stasis and Hypercoagulability.
The central retinal vein and artery share a common adventitial sheath at arteriovenous crossings posterior to the lamina cribrosa. Atheroscleortic changes of the artery may compress the vein and cause CRVO.
Some risk factors include diabetes, hypertension, hyperlipidemia, raised intraocular pressure, hypercoagulable states etc.
It is important to distinguish between ISCHEMIC vs NON-ISCHEMIC CRVO
Image from Rajan Eye Care Hospital