The refractive changes and long-term (3 years) results of radial keratotomy performed at high altitude.

PURPOSE To evaluate the development of regression or progression following radial keratotomy (RK) performed at high altitude (1,720 meters) at long-term follow-up (3 years). METHODS Thirty-nine eyes of 21 myopia patients (between -3.25 D and -11.00 D) whose ages were 19-32 years were included in the study. The RK procedures were performed in standard Russian style. RESULTS The average spherical equivalent cycloplegic refractions were -5.49 D +/- 2.08 (SD) preoperatively, -1.64 +/- 1.59 D in the short-term (3.41 +/- 1.46 months) and -1.40 +/- 1.71 D in the long-term (30.72 +/- 4.36 months) follow-up period. There was no statistically significant difference between these values at the short- and long-term follow-up measurements (t = -1.57, P =.12). CONCLUSIONS The refractive changes following RK performed at high altitude occur through a combination of both the direct effect of reduced barometric pressure and the edematous corneal expansion because of hypoxia. An ophthalmologist performing RK surgery at high altitude must consider the long-lasting therapeutic effects of high altitude surgery compared to surgery at sea level.