a 52-year - old male patient presented at our hospital with progressive unilateral proptosis since 2 years ago and vision loss in his left eye . ocular examination revealed 2 + relative afferent pupillary defect in the left eye . computed tomography scan of the patient showed an intraconal mass sticking to superior ophthalmic fissure [ fig . 1 ] . the procedure was done without complication , and the early postoperative vision was fine but about an hour later , patient developed sudden vision loss and became no light perception ( nlp ) . for ruling out postoperation hemorrhage , fundus examination with indirect ophthalmoscopy revealed typical view of crao with the presence of cherry - red spot on the macula , white ground - glass appearance of the retina , and optic disc edema [ fig . 2 ] . for decreasing intraocular pressure and establishing retinal reperfusion , immediate ocular massage and anterior chamber paracentesis as well as systemic therapy with mannitol were done . two hours later , it was improved to 1 m counting finger , but he complained a large central scotoma . his va improved to 20/200 the day after the surgery , and he complained of diplopia . orbital computed tomography - scan of the patient shows well - defined dumble shaped intraconal orbital mass that pushed the optic nerve superomedially and extending to the supra orbital fissure fundus photograph 3 days after the surgery showing cherry - red spot on the macula and white ground - glass appearance of the retina and also optic disc edema medical workup did not show any evidence of collagen vascular or cardiovascular , hematologic , and neurologic disorders . systemic investigations including fasting blood sugar , lipid profile , and homocysteine levels all were normal . crao is usually caused by a thrombus or embolus that resulting to reduce blood perfusion of the retina . it clinically presents as sudden painless acute unilateral or bilateral vision loss in the range of counting fingers to nlp . the rate of spontaneously recanalization of the artery is about 15% with timely intervention , the prognosis is very poor as only 61% of patients can regain a final va of 6/120 or less . one of the typical findings in crao is cherry - red spot that is found in about 90% of cases . there is a golden time of 90120 min after occlusion to perform interventions to improve vision , however there is no approved modality to be effective in the treatment of crao , but some methods such as immediate ocular massage and anterior chamber paracentesis , use of drugs such as intravenous acetazolamide and mannitol or inhalation of a mixture of 95% oxygen and 5% carbon dioxide ( carbogen ) , all aimed to reduce intraocular pressure and improving blood flow to the eye . without doing these modalities , < 10% of patients can recover meaningful vision . multiple theories for crao during surgical procedures have been proposed ; a prolonged hypotensive status and reduction in blood flow or also increasing intraocular pressure including ocular compression during certain ocular surgical procedures associated with ocular ischemia , causing ischemia of the retina and may lead to crao and vision loss after surgery . although we did not face any significant drop in blood pressure ( bp ) during intervention but regarding differences in populations may be our patient was very sensitive to even small drop in bp that could lead to crao . in another theory , krner - stiefbold explains that retrobulbar masses such as hematoma , neoplasms , and retrobulbar injections may compress central retinal artery and lead to arterial occlusion and decrease blood perfusion causing crao . a more likely explanation in that ocular vascular damage may be happened by surgical maneuvers , and it will results in activation and aggregation of platelets and activated platelets release serotonin ( 5-hydroxytryptamine ) . serotonin is a vasoconstrictor and inducing transient arterial spasm , causing transient or complete arterial occlusion leading to ischemia of retina and creating crao . we recommend that in all patients with orbital tumors that undergo tumor removal , the ocular exam should be performed immediately , and every 13 h after the surgery to rule out crao , as delay in diagnosis and intervention could eventuate to severe vision loss .