Crossover to acetazolamide for the treatment of cystoid fluid collections in X-linked retinoschisis: the REAXIS study

INTRODUCTION: This prospective study evaluated the pharmacologic effect of oral acetazolamide on structural and functional outcomes in patients with X-linked retinoschisis (XLRS) using a cross-over design. METHODS: Five male participants from the prior AXIS control arm received oral acetazolamide 250 mg twice daily for 32 weeks, with dose adjustments based on structural response and follow-up to week 64. The primary endpoint was the central subfield thickness (CST). Secondary measures included best-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), retinal sensitivity on microperimetry (MP), cystoid fluid collection volume (CFCV), and patient-reported outcomes via the Michigan Retinal Degeneration Questionnaire (MRDQ). RESULTS: = 0.001; 95% CI - 117.2 to -28.4) was observed between the control and treatment periods on average over time with responses varying among patients. Statistically significant but modest improvements in BCVA, LLVA and retinal sensitivity on MP were also observed. Common treatment-related side effects included fatigue, paresthesia, dysgeusia, and tinnitus, leading one patient to discontinue treatment. CONCLUSIONS: While the REAXIS crossover study demonstrated statistically significant improvements in CST, BCVA, and LLVA, the effect sizes were modest and highly variable across individuals. These findings support further exploration of personalized treatment strategies and predictive biomarkers in XLRS.