Rates of visual acuity change in patients receiving hyperbaric oxygen in monoplace and multiplace chambers.

INTRODUCTION: Changes in visual acuity are a known side effect of hyperbaric oxygen (HBO₂). We conducted a quality improvement initiative to better quantify visual change risk and to identify possible risk factors. METHODS: Vision was checked weekly in a clinical HBO₂ population by Snellen eye chart. Visual acuity change was defined as Snellen test worsened to 20/40 or greater or by loss of 2 lines. RESULTS: Of 85 patients treated from January 2013 to February 2015 with 10 HBO₂ sessions and ≥ 2 weeks of visual acuity testing, 53 (62%) were male. All were treated for UHMS-approved indications. A total of 34 patients (40%) had no change in visual acuity, 27 (32%) had a 1-line change, and 24 (28%) had at least a 2-line worsening in visual acuity. The number of sessions for those with at least a 2-line change was 36 ± 15 (15-60). A 2-line change occurred at similar rates for monoplace and multiplace patients (29% and 32%, respectively), but monoplace patients more frequently reached 20/40 or worse (32% vs. 18%). Seven of 11 patients with existing cataracts had ≥ 2 line change, as did six of 14 patients (43%) with a history of head/neck radiation. CONCLUSIONS: In this retrospective review of quality improvement data, 28% of patients had a 2-line change in visual acuity by Snellen exam after treat-ment with HBO₂. Further study of possible risk factors, including chamber type, is warranted.