High altitude retinal hemorrhage or HARH is one of the health risks of being exposed to high altitude. However, high altitude retinal hemorrhage has attracted little notice in medical literature. Some experts and researchers have mentioned the findings of vitreous hemorrhage, diminished vision, etc. on being exposed to high altitude.
Not much is known about HARH.
Researchers have noticed that those who have gone to about 4270 m and above have developed bilateral retinal hemorrhage, along with other clinical manifestations such as acute mountain sickness, and high altitude pulmonary edema. Clinicians carry out funduscopic assessment to establish whether there is macular retinal hemorrhage.
High Altitude Retinal Hemorrhage Symptoms
The clinical features, symptoms and manifestations, along with fundoscopic examination are:
Retinal hemorrhage does not occur in all those who go to high altitudes; in fact statistics state that retinal hemorrhage occurs in about 5 % of people staying at high altitude.
Associated features include – high altitude pulmonary edema and acute mountain sickness.
Hemorrhage is associated with dilatation of retinal vessels, but papilla-edema is not seen. The hemorrhages are flame shaped and scattered all over the fundus. Occasionally, exudate is seen with the hemorrhages. Hemorrhage is usually small and confined to the macula. Infrequently, massive vitreous hemorrhage (in one eye) and retinal hemorrhage with, neo-vascularisation may occur.
About 50 % cases tend to develop bilateral lesions, and hypothesis says that it is probable that unilateral cases remaining under the long-drawn-out hypoxic stress tend to become bilateral.
High altitude hypoxia results in dilatation of the retinal blood vessels, increase in retinal blood flow, impairment of the retinal vessels and raised capillary permeability leading to retinal hemorrhage. These develop are more in those people who have stayed for a prolonged interval of time at high altitude. The sustained and constant hypoxic stress causes lots of impairment to retinal capillaries. Neo-vascularisation develops as a compensatory mechanism.
Studies show that hemorrhages related to high altitude pulmonary edema get totally absorbed with the subsidence of the pulmonary edema. On the other hand, everlasting visual disabilities may develop in some cases.
High Altitude Retinal Hemorrhage Treatment
Patients diagnosed with high altitude retinal hemorrhage are treated with iso-volemic hemo-dilution, aspirin and pentoxifylline, which decreased hematocrit to 41 %. By and large, the visual acuity and visual field return to normal, and the intra retinal hemorrhage tends to get resolved.