High-altitudes may cause eye swelling

ZURICH, Switzerland, Feb. 9 (UPI) -- Swiss scientists say they've discovered mountain climbers may experience swelling of their corneas, but the condition does not appear to affect vision.

The researchers from University Hospital in Zurich, Switzerland, said the swelling commonly occurs at altitudes of up to about 20,670 feet and has been feared to cause potentially hazardous vision loss.

In the study, Dr. Martina Monika and colleagues studied the effects of high-altitude climbing on corneal thickness among 28 healthy volunteers climbing Mount Muztagh Ata in western China.

The mountaineers were randomly assigned to two different ascending paths, with one group being allotted a shorter time to acclimate before ascending to about 20,500 feet. Corneal thickness, visual acuity and blood oxygen levels were measured in climbers before, during and after their ascent.

In groups with both patterns of ascent, corneal thickness increased with increasing altitude and decreased after descent. The group with the shorter acclimatization time experienced a greater increase in corneal thickness. But the scientists said no significant decrease in visual acuity was observed in either group.

The findings are detailed in the journal Archives of Ophthalmology.