Background: Hyperbaric oxygen therapy (HBOT) involves exposing patients to elevated oxygen pressures and concentrations for a series of 2 hour sessions. It is commonly used with multiple exposures to treat soft tissue degenerative diseases, but a side-effect for some patients is a significant increase in myopia.
Phase 1: Four subjects receiving 20 or more 2 hour HBOT sessions for soft tissue disease participated in this phase of the project. Visual acuities and refractive error corrections were determined before and after HBOT sessions at the beginning, midpoint, and end of therapy. No subjects showed significant acuity or refractive error changes produced by single HBOT sessions. One subject showed a significant increase in myopia over the 20 session course of HBOT.
Phase 2: Four additional subjects receiving HBOT for soft tissue disease participated in this phase. Visual acuity, refractive error correction, A-scan ultrasound, and corneal curvature measurements were made before and after selected HBOT sessions. In addition, susceptibility to free radical damage and indicators of actual damage were measured by analysis of blood drawn before and after selected sessions. During the first half of HBOT therapy, subjects took placebo tablets; during the second half they took antioxidant supplements. None of the subjects showed significant effects of single HBOT sessions. However, one subject showed a significant increase in myopia over the course of HBOT. No corresponding changes were found in the ultrasound, corneal curvature, or blood analysis data. The rate of myopia progression was approximately the same for placebo and antioxidant supplement periods.
Discussion: Two of the 8 subjects experienced significant increases in myopia as a result of HBOT. It is likely that this increase was caused by lenticular refractive index changes due to oxidative damage. It was not possible to predict which subjects were susceptible to myopia increase nor was evidence of oxidative damage found by blood analysis. Antioxidant supplementation did not slow the rate of myopia development.
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