Central Retinal Artery Occlusion in Young Adults at High Altitude: Thin Air, High Stakes.

Rana, Vipin, Pradeep Kumar, Sandeepan Bandopadhyay, Vijay K. Sharma, Meenu Dangi, Dattakiran Joshi, Sanjay Kumar Mishra, Satyabrat Srikumar, and V.A. Arun. Central retinal artery occlusion in young adults at high altitude: thin air, high stakes. High Alt Med Biol. 00:000-000, 2024.-We present five cases of young security personnel who were posted at high altitude (HA) for a duration of at least 6 months and presented with a sudden decrease of vision in one eye. The diagnosis of central retinal artery occlusion (CRAO) was made in all patients. Fundus fluorescein angiography and optical coherence tomography of the macula supported the diagnosis. None of these cases had any preexisting comorbidities. Erythrocytosis was noticed in all patients, and two of them had hyperhomocysteinemia. Four out of five patients showed either middle cerebral artery or internal carotid artery (ICA) thrombosis on computed tomography angiography. The patients were managed by a team of ophthalmologist, hematologist, vascular surgeon, and neurologist. In cases of incomplete ICA occlusion, patients were managed surgically. However, in the case of complete ICA occlusion, management was conservative with antiplatelet drugs. This case series highlights HA-associated erythrocytosis and hyperhomocysteinemia as important risk factors for CRAO in young individuals stationed at HA.

Retinal Manifestations in High Altitude.

Dangi, Meenu, Arnab Sadhukhan, Poninder Kumar, S. Bandopadhayay, Vijay K. Sharma, V.K. Patra, Manu Chaudhary, and Vipin Rana. Retinal manifestations in high altitude. High Alt Med Biol. 24:296-301, 2023. Aim: To study the high altitude (HA)-related retinal manifestations among security personnel and thus to provide new insights into the characteristics and mechanisms of retinopathy. Materials and Methods: This was a multicentric, nonrandomized prospective observational and descriptive study. We studied 54 security personnel over 1 year, who were referred from HA areas of northern India and north-eastern India for ocular problems. Complete coagulation profile was performed among patients with vascular occlusion. Results: There were total of 54 patients with ages ranging from 22 to 55 years. HA retinopathy was noticed in 28 patients: central retinal vein occlusion (6 patients), branch retinal vein occlusion (4 patients), branch retinal artery occlusion (1 patient), central retinal artery occlusion (4 patients), ocular ischemic syndrome (1 patient), central serous chorioretinopathy (7 patients), acetazolamide-induced maculopathy (1 patient), and solar retinopathy (2 patients). Along with an increased hematocrit, serum homocysteine was raised in the majority of vascular occlusions. The mean age was 38.16 years, the mean altitude was 14,716 ft, and the mean duration of stay was 11.2 weeks. Conclusion: Hypobaric hypoxia due to HA is a potential risk for HA retinopathy and associated vascular occlusions. Aside from increased hematocrit, hyperhomocysteinemia is a potential cause of vascular occlusions.

Hyperhomocysteinemia, High Altitude, and Varied Retinal Manifestations: Unravelling the Enigma.

Rana, Vipin, Meenu Dangi, Sandepan Bandopadhayay, Vijay K. Sharma, Satyabrat Srikumar, Jitesh Goyal, and B.V. Rao. Hyperhomocysteinemia, High Altitude, and Varied Retinal Manifestations: Unravelling the Enigma. High Alt Med Biol. 24:234-237, 2023.-We present five cases of young defense personnel, who were posted at high altitude (HA) for >6 months and presented with reduction of vision between June 2022 and February 2023. The diagnosis made were ocular ischemic syndrome, central retinal artery occlusion, central retinal vein occlusion, branch retinal vein occlusion, and branch retinal artery occlusion. There were no associated comorbidities. Hematological workup revealed increased serum homocysteine and hemoglobin in all patients. Computed tomography angiography was done in cases of ocular ischemic syndrome, and central retinal artery occlusion, which revealed occlusion of carotid artery. All patients were given tab folic acid in view of hyperhomocysteinemia (HHcy). This case series highlights that prolonged exposure to HA may lead to HHcy, which can directly or indirectly lead to various sight-threatening retinal diseases. Thus, effective preventive strategies, such as dietary or pharmacological interventions aimed at lowering serum homocysteine levels, are crucial for individuals posted at HA for longer duration.