Effects of High Altitude Related Oxidative Stress on Intraocular Pressure and Central Corneal Thickness – A Research Model for the Etiology of Glaucoma

Glaucoma is a progressive optic neuropathy resulting in axonal death and is a leading cause of blindness. Several factors play a role in this progressive cell loss. Hypoxia and oxidative stress are among the risk factors for glaucomatous changes. Tissue stress is also very crucial in glaucoma. This fact is evidenced by stress proteins and heat shock proteins in glaucoma models (Tezel & Wax, 2007). A relatively undiscovered field, namely high altitude related oxidative stress has recently gained attention in glaucoma research. High altitude, which is usually regarded as an altitude over 2,400m, has various effects on the human body. Mountaineers, outdoor sports enthusiasts, military as well as other personnel working at high altitudes are at risk and the detrimental effects caused by high altitude hypoxia can reduce their performance. At high altitudes, atmospheric pressure gradually falls and the oxygen partial pressure decreases. The resultant hypobaric-hypoxia with an oxygen partial pressure < 60mmHg is the culprit for detrimental effects of high altitude. High altitude may lead to a constellation of symptoms including acute mountain sickness, or in extreme cases, high altitude pulmonary edema or high altitude cerebral edema. At high altitude, hypoxia, ultraviolet rays, cold and increased energy need are amongst other contributing factors. The human eye is also affected by hypoxia at high altitude and extensive research is being carried out by various teams all around the world. Erciyes University Medical Faculty is located at the skirts of Erciyes Mountain (3,917m), Kayseri, Turkey. Inspired by the Turkish ophthalmic surgeon, Dr. Bozkurt Ergor (1927-2009), who had practised ophthalmology in Kayseri, served as the president of Turkish Mountaineering Federation and climbed to numerous peaks all over Turkey and the world, we carried research on high altitude ophthalmology at Erciyes University Medical Faculty Department of Ophthalmology (Ergor, 2011; Karakucuk et al., 2000, 2004, 2010). (Figures 1 & 2). In this chapter, effects of high altitude on central corneal thickness and intraocular pressure will be reviewed and the topic discussed in the light of the relationship of these parameters with high altitude related oxidative stress.