Myopic Shift in Patients During Hyperbaric Oxygen Treatment: A Systematic Review

CReversible myopic shift (MS) is a common side effect of hyperbaric oxygen treatment (HBO₂) resulting from refractive changes in the lens. Single studies indicate that the myopic shift increases with longer duration of HBO₂ and may differ between hyperbaric chamber types and oxygen breathing systems. This review aims to improve knowledge on the frequency and magnitude of myopic shift after standard-length HBO₂.

A systematic search for original studies of myopic shift after HBO₂ was conducted in medical databases. Included were published full-text articles in English with specified details on oxygen administration, pressure, number of treatments, and use of conventional techniques to measure refraction. Studies with exposure other than HBO₂, patients with artificial lenses, and single-case reports were excluded.

Of 153 reports identified, eight studies with 263 patients were included. Treatment durations covered 18-21, 30, and 40 treatments in either monoplace or multiplace chambers using hoods or masks. For the mean values of myopic shift and the incidence of a myopic shift ≥ 0.5 D, a range was seen from the lowest values after 20 treatments in multiplace chambers using a mask (0.4 D and 53%, respectively), to the highest values after 40 treatments using hoods (1.6 D and 100%, respectively). For monoplace treatment, the corresponding numbers were 0.6 D and 70% after 18 treatments, and 0.95 D and 91% after 30 treatments.

This review indicates that both the magnitude and incidence of myopic shift increase with the number of HBO₂ sessions and in the order multiplace-mask < monoplace < multiplace-hood.