NEWS: 16th Apr 2007
 
High Altitude Eye Study

As part of the Neuroscience work we are carrying out the most extensive high altitude eye study. The eye is really an extension of the brain and hence it is a very useful window for us to look at to give us an idea of what might be going on behind it.

Ascent to high altitude is associated with the formation of retinal haemorrhages; tiny bleeds at the back of the eye. Over 80% of people summiting Everest will develop such haemorrhages.

TOPCON have very kindly supplied us with one of the latest non-mydriatic cameras (pictured) which is enabling us to take very high quality retinal images of our team and the 203 trekkers. Graeme Holland and Derek Styles of Holland Opticians, Malvern, walked in with us and made sure all the kit was working ? they left with Jim Milledge (pictured) a couple of days ago and are now heading back to Kathmandu via the Cho La Pass and Gokyo Ri.

We are obtaining superb images ? the adjacent figure is an example. The camera is working extremely well after we defrost it in the mornings! We used a less sophisticated camera on Cho Oyu last year and found that 7 of the 17 climbers developed marked retinal haemorrhages.

This year we will be able to correlate retinal haemorrhages with symptoms of acute mountain sickness. We are also performing some other eye experiments, for example, we are monitoring intraocular pressure with a small hand-held monitor kindly supplied by i-care, and we are measuring pupillary reaction with a NeuroOptics ForSite Pupilometer kindly supplied by Medtronic.

With these and other investigations, we hope to be able to provide a pathogenic mechanism for high altitude retinal haemorrhages.

Mark Wilson