<prompt> True about CRAO:Embolism of artery main causePainful loss of visionTrucking of vessel is seenInvolvement of Ophthalmic Artery  <response>: Ans. C. Trucking of vessel is seen Ref: Yanoff ophthalmology. 4thed p518-521; Parsons Diseases of the Eye 22nded p320-21Explanation Central retinal artery obstruction CRAO is an abrupt diminution of blood flow through the central retinal artery severe enough to cause ischemia of inner retina. Mean age is 60 yrs Men affected more 2:1 Majority of CRAO caused by thrombus formation at or just proximal to lamina cribrosa. 20-25 cases are due to emboli Atherosclerosis main cause, inflammation vasculitis, mucormycosis Manifestation: Abrupt painless diminution of vision DOV but no light perception uncommon, can occur if associated with ophthalmic artery Amaurosis fugax precedes visual loss in 10 Ischemic whitening of retina more so at posterior pole Cherry rod spot at macula Cattle truck appearance: when obstruction is not complete, the flow may be partially restored in the course of few days in which case gentle pressure upon the globe may break up the column of venous blood into red beads separated by clear spaces NVD 2 and NVI 18 may result Inner retinal atrophies apart from outer retina which receives nourishment from choroid If cilioretinal retinal artery is present macular sparing occurs.Diagnosis: FA: Delayed arm to retina time OCT: Acute phase inner retinal thickening and later thinning ERG: Absent b wave with intact a wavePathology: Coagulative necrosis of inner retinal tissue Treatment Breathing carbogen to increase retinal oxygenation Increase in retinal blood flow by lowering IOP: Ocular massage, paracentesis or ocular hypotensive drug Intravenous thrombolysis 