True about CRAO:

Ans. C. Trucking of vessel is seen Ref: Yanoff ophthalmology. 4th/ed p518-521; Parsons' Diseases of the Eye 22nd/ed 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