Abstract WP016: Visual Acuity Trends in Central Retinal Artery Occlusion During Treatment with Hyperbaric Oxygen Therapy

Introduction: Non-arteritic central retinal artery occlusion (CRAO) is an ophthalmic emergency often considered a stroke equivalent which portends a poor prognosis. Hyperbaric oxygen (HBO) therapy has been associated with improved final best corrected visual acuity (BCVA) in recent studies. Data regarding the effect of HBO on BCVA throughout the time course of treatment remain lacking. Clinically, we observe that visual acuity, while initially improved after HBO, worsens in the hours after treatment. We hypothesized that a) there is decay in visual acuity over the 6 hours following a single HBO treatment, and b) that serial HBO treatments yield diminishing improvements in BCVA over time. Methods: We conducted a retrospective single-center study of non-arteritic CRAO patients treated with HBO from June 2014 – October 2023. For each patient, we recorded: all BCVAs then performed log transformation (LogMar). We also recorded the approximate time of BCVA exam and time of each treatment. We used a) change from presenting BCVA or b) change in BCVA from the previous treatment as the outcomes. We excluded any BCVA measured at more than 6 hours. We used a linear regression model to determine the association between time and change in visual acuity from presenting. Then, we used a linear mixed-effects model with treatment number as a within-subject factor, participant included as a random intercept, and the Bonferroni method for adjustment during post-hoc analyses. Results: A total of 148 patients were included. Time since HBO was negatively correlated with change in BCVA (slope = -0.088 ± 0.02 LogMar/hour, p=0.0001, n=721), adjusted R2 was 0.019 (Figure 1). Treatment number was associated with mean change in visual acuity from presenting (p = 0.001); post-hoc analyses showed significant improvement after treatment 7 (0.54 ± 0.09) compared to treatments 1, 2 and 4. Treatment number was also associated with change in visual acuity from previous treatment (p=0.01), with a significant difference between treatment 1 and treatment 4 (Table 2). Conclusion: There is a small but significant association between BCVA and time since HBO treatment, which should be considered when making treatment decisions. Additionally, there is a dynamic response of visual acuity over the treatment course, suggesting a potential plateau effect. Future studies are warranted to improve the optimal treatment course in non-arteritic CRAO.