High Altitude Retinopathy in an Emergency Physician Working at Everest Base Camp: A Case Report

Introduction

High altitude illness is a heterogeneous entity covering the wide range of symptoms in people who are exposed to high altitude, including tourists, athletes, aviators, trekking guides, residents from birth, and people performing professional duties such as police and soldiers. ¹ High altitude retinopathy (HAR), a spectrum of pathologic retinal changes that occur in unacclimatized individuals exposed to hypobaric hypoxia at high altitudes, was first described by Singh et al. ²

Important features of high altitude retinal changes include retinal vessel engorgement and tortuosity, optic disc hyperemia, reduced retinal circulation time, and an absolute rise in retinal vascular blood volume. ³ A classification of HAR was provided by Wiedman and Tabin, ³ and it mainly included retinal vessel dilatation and tortuosity, optic disc edema, high altitude retinal hemorrhages, and vitreous hemorrhages. HAR is usually asymptomatic, does not or slightly affects vision, and generally resolves spontaneously on the descent to lower altitudes; rarely does a patient with HAR develop permanent vision loss.

Climbers who ascend >3000 m above sea level are more prone to HAR. ⁴ People who ascend rapidly, unacclimatized individuals, and people experiencing such extreme altitude for the first time are at higher risk of developing HAR.

Case Report

A 31-year-old male emergency physician who had been working in Belgium at sea level traveled to Nepal as an expedition doctor. He had followed the proper ascend profile in his trek, and he had been working at Everest Base Camp for 2 wk at an altitude of 5300 m. He had been actively involved in the activities at the base camp, including icefall training sessions and acclimatization hikes, which were quite intense. He had not slept much the 2 nights prior because he was looking after a few sick patients. On the morning of the incident, he was enjoying a cup of coffee during breakfast when he suddenly noticed a sudden onset of visual disturbances, specifically scotoma, in the visual field of his right eye. Initially, he thought it might be an aura of one of his usual migraines, but he quickly realized that wasn’t possible because it was monocular. He reported no other symptoms such as breathlessness, confusion, loss of coordination, tingling, numbness, or weakness. Initial assessment at the Everest ER clinic revealed retinal hemorrhage in the right eye, and the patient was told descend down. He then hiked down to the village of Pheriche, where he was evacuated to Lukla by helicopter the next morning. He stayed on oxygen that night and transferred to a travel medicine clinic in Kathmandu for further evaluation.

On examination, his visual acuity was decreased in the right eye but normal in the left eye. Direct and consensual light reflexes were intact, and bilateral nasal and temporal visual fields were preserved. Ocular movements were normal, and the anterior chamber depth was nearly fully illuminated. Fundus examination of the right eye showed multiple cotton wool spots medial to the central region and blotchy retinal hemorrhages in the macular area (Figure 1). The retinal veins were dilated in both eyes. An ultrasound of the right eye did not show any retinal tears or detachment, and the optic nerve thickness was measured at 4.5 mm. The patient had a previous history of migraine headaches but had no other significant medical history or history of medication use.

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Figure 1.

Right eye fundus photograph of retinal hemorrhages in the macular area.

Based on these findings, the patient was diagnosed with high altitude retinal hemorrhage (HARH). To manage the condition, he was prescribed ketorolac tromethamine ophthalmic solution, one drop in the affected eye qid for 4 wk. The patient decided to halt his ascent and return home. His recovery was gradual, with persistent scotoma lasting up to 8 wk, but eventually, the symptoms resolved completely without the need for surgical intervention.

Discussion

Common high altitude illnesses include acute mountain sickness, high altitude cerebral edema (HACE), high altitude pulmonary edema, and HARH, which is a condition that can occur in unacclimatized individuals exposed to high altitudes due to the hypobaric hypoxia experienced at high altitudes. ⁵ It is the result of a systemic hypoxic effect on the eye. The pathophysiology involves vasodilation and increased blood flow, which leave retinal vessels vulnerable, leading to retinal bleeding. The viscosity of the blood is also increased due to polycythemia at high altitude, which is associated with venous engorgement and hemorrhage. ⁶ The hemorrhages usually occur in the nerve fiber layer, presenting as flame- or wedge-shaped or “dot-and-blot” hemorrhages, cotton wool spots, and other retinal changes in individuals having an inadequate autoregulatory response.^1,4 Hypoxia triggers dilation of retinal blood vessels and the growth of capillaries, making them more susceptible to a sudden increase in intravascular pressure during coughing, straining, or intense physical activity. ⁴

In mild cases, hemorrhages affect the peripheral retina and usually avoid the macula, so in most cases the retinal hemorrhage is asymptomatic. ⁴ As the condition worsens, macular hemorrhages may occur, leading to scotoma. When patients experience conditions such as vitreous hemorrhage, macular hemorrhage or edema, retinal vein occlusion, or papilledema, they can suffer from significant vision loss and visual field defects. In rare instances, severe vision issues such as ischemic optic neuropathy, cortical blindness, and permanent myopia may result from high altitude exposure. ⁷ In this case, the patient's symptoms and examination findings were consistent with HARH, including decreased visual acuity in the affected eye, retinal hemorrhages, and cotton wool spots

Climbers with extremely low oxygen levels experienced more retinal bleeding during expeditions. Additionally, the higher they ascend and the longer they stay at high altitudes, the more frequent the retinal hemorrhages become. ² HAR is closely associated with high altitude pulmonary edema and HACE in many cases, but in this patient, signs of other high altitude illnesses were not seen. Clarke et al ⁸ questioned whether isolated retinal hemorrhages signal the onset of cerebral edema. In contrast, Wiedman and Tabin ³ suggested a potential link between HAR and HACE.

Coughing, vomiting, weightlifting, and the Valsalva maneuver increase the risk of retinal hemorrhage. ⁶ In our case, the patient didn’t have coughing and vomiting, but he was engaged in training and was physically more active on those days, which may have increased the risk. The patient's decision to stop his ascent and return home was crucial in preventing further deterioration of his vision. Subsequently, the use of ketorolac tromethamine ophthalmic solution and hyperbaric oxygen was an appropriate management step, because some reports suggest that the use of nonsteroidal anti-inflammatory drugs, steroids, and oxygen may be beneficial, which helped in reducing inflammation and promoting recovery.^3,9 HARH is generally self-resolving with descent and supportive care. The prognosis of this disease is favorable, with patients generally regaining full vision in weeks after descent. However, the persistence of scotoma for up to 8 wk indicates that recovery can be prolonged and may require ongoing monitoring.

A key challenge noted is that mountaineers and high altitude travelers are frequently hesitant to descend, even when they develop high altitude illnesses, because of the significant time and financial resources already invested in their journey. If macular involvement is identified, patients should be cautioned against continuing their ascent or engaging in activities that could exacerbate hypoxemia or elevate intraocular pressure until the condition improves.

Conclusion

In conclusion, this case emphasizes the need for vigilance among medical personnel working in such settings and the importance of prompt descent and appropriate medical therapy for favorable outcomes. Future research should focus on further elucidating the pathophysiology and risk factors of HARH and optimizing management strategies to improve patient outcomes.