High-altitude climbs may cause corneal swelling, but do not appear to affect vision

Feb 08, 2010

Swelling commonly occurs in the corneas of mountain climbers, but does not appear to affect vision at altitudes of up to 6,300 meters (about 20,670 feet), according to a report in the February issue of Archives of Ophthalmology.

"High-altitude mountaineering is a popular recreational sport among healthy lowlanders," the authors write as background information in the article. "As a consequence of the exposure to hypobaric atmospheric conditions with a consecutive decrease in , high-altitude climbing may lead to acute mountain sickness and the rare but potentially fatal high-altitude cerebral edema." Changes to the cornea, the transparent membrane covering the front of the eye, also occur during high-altitude climbs and may cause potentially hazardous .

Martina Monika Bosch, M.D., of University Hospital Zurich, Switzerland, 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 6,265 meters. Corneal thickness, visual acuity and blood oxygen levels were measured in climbers before, during and after their ascent, and symptoms of acute mountain sickness were also assessed.

In groups with both patterns of ascent, corneal thickness increased with increasing altitude and decreased after descent, and the amount of decrease in blood oxygen levels paralleled this increase. The group with the shorter acclimatization time experienced a greater increase in corneal thickness. However, no significant decrease in visual acuity was observed in either group.

When controlling for age and oxygen saturation, there was a correlation between symptoms of mountain sickness and corneal thickness. This was possibly due to these individuals' higher overall susceptibility to inadequate oxygen supplies.

The exact cause of corneal swelling during ascent remains controversial, the authors note. The current findings suggest that the body's delivery of oxygen to the aqueous humor—the fluid inside the eyeball, between the cornea and iris—may be more important in corneal oxygen levels than previously thought.

"It seems that visual acuity in healthy is not adversely affected despite the presence of edema at altitudes up to 6,300 meters," the authors conclude. However, it is likely that ascents to more extreme altitudes—above 8,000 meters or about 26,000 feet—may induce greater damage to the cornea and lead to dangerous visual loss.

Explore further: Running really can keep you young, study says

More information: Arch Ophthalmol. 2010;128[2]:184-189.

add to favorites email to friend print save as pdf

Related Stories

Research team explores causes of death on Mount Everest

Dec 10, 2008

An international research team led by Massachusetts General Hospital (MGH) investigators has conducted the first detailed analysis of deaths during expeditions to the summit of Mt. Everest. They found that most deaths occur ...

Scientists tackle mystery mountain illness

Aug 21, 2007

Experts at the University are studying an illness known as HAPE (high altitude pulmonary oedema), which causes fluid to build up in the lungs can and can occur from as low as 2,500 metres, affecting people of all age groups ...

Recommended for you

Running really can keep you young, study says

2 hours ago

If you are an active senior who wants to stay younger, keep on running. A new study involving the University of Colorado Boulder and Humboldt State University shows that senior citizens who run several times ...

The American athletics track is still a man's world

3 hours ago

The limited coverage that American female athletes get in the media is one of many subtle forms of gender biases they have to cope with. The little exposure they do get often focuses more on their attire, or how attractive, ...

How do teenage boys perceive their weight?

6 hours ago

Almost one third of male adolescents inaccurately perceive their weight. This can influence their eating habits and, consequently, their health, according to a study led by the UAB and conducted with 600 teenage boys from ...

Cold front sparks dangerous use of space heaters

6 hours ago

The Consumer Product Safety Commission (CPSC) estimates that more than 25,000 residential fires and more than 300 deaths are caused each year by space heaters. More than 6,000 Americans receive hospital emergency room care ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.