Why this review matters for X-linked retinoschisis
X-linked retinoschisis (XLRS) is an inherited retinal condition in which the layers of the retina can separate, or “split.” These structural changes often affect the macula—the central part of the retina responsible for detailed vision. On optical coherence tomography (OCT), a non-invasive retinal scan, this may appear as spaces or cyst-like cavities within the retina. These macular changes can contribute to reduced central vision and are an important focus of care and research.
A 2026 systematic review in Cureus examined whether topical carbonic anhydrase inhibitors (CAIs)—medicated eye drops such as dorzolamide and brinzolamide—can help reduce macular edema across a range of retinal disorders. The review is especially relevant to the XLRS community because 10 of the 28 included studies involved people with XLRS, making it one of the most studied conditions in the analysis.
What are carbonic anhydrase inhibitor eye drops?
Carbonic anhydrase inhibitors are medicines that affect fluid movement in the eye. In this setting, they are used with the goal of reducing fluid-related retinal swelling or cyst-like changes in the macula. Unlike treatments that require an injection into the eye, dorzolamide and brinzolamide are delivered as eye drops.
The review searched PubMed, Scopus, Web of Science, and the Cochrane Library through June 13, 2026. It included clinical studies of topical dorzolamide or brinzolamide for macular edema from any cause. The 28 eligible studies included randomized trials as well as observational studies, such as cohorts and case series. Overall, the authors judged the included studies to have moderate-to-high methodological quality, although the types of patients, treatment schedules, follow-up periods, and outcomes varied substantially.
Key finding: retinal anatomy often improves
Across the retinal diseases studied, topical CAIs consistently reduced central macular thickness and improved retinal appearance on OCT. In straightforward terms, the scans often showed less fluid or fewer cyst-like changes after treatment.
For families affected by XLRS, this is encouraging because OCT changes are clinically meaningful: they provide a way to monitor the structure of the macula over time and assess whether treatment is affecting the retinal spaces associated with schisis.
However, the review also highlights an essential distinction. Improvement on an OCT scan does not always translate into a major improvement in measured vision. In XLRS, visual gains were generally modest, even when anatomical changes were seen. This does not mean that structural improvement lacks value; rather, it shows that retinal structure and visual function do not always recover in parallel.
Why might vision improve less than the scan?
The authors suggest several possible reasons for the gap between anatomical and functional outcomes. Long-standing retinal changes may involve photoreceptor loss, dysfunction of the retinal pigment epithelium, or irreversible disruption of the ellipsoid zone. The ellipsoid zone is an OCT feature associated with photoreceptor health. If these vision-sensing cells or their supporting structures have already been substantially affected, reducing fluid or retinal thickness may not fully restore visual function.
This is particularly important in XLRS, where the disease involves more than simple fluid accumulation. The retinal splitting characteristic of XLRS reflects an underlying inherited structural disorder. Therefore, an eye drop that improves macular appearance may address one aspect of the condition without correcting its genetic cause.
What this means for treatment today
The review supports topical CAIs as a non-invasive treatment option for selected people with XLRS who have macular changes that may be responsive to therapy. Dorzolamide was the agent evaluated most often, while brinzolamide was studied less frequently. Across the included conditions, topical CAIs were well tolerated, with no serious ocular or systemic adverse events reported.
The evidence also reinforces the value of individualized monitoring. OCT can document whether the macula changes during treatment, while visual acuity testing helps determine whether those structural changes are accompanied by functional benefit. Because responses may differ from person to person, both types of measurement are important.
The review does not establish one ideal treatment schedule, duration, or long-term strategy for XLRS. Its findings instead show that eye drops can be a useful management tool in selected cases, while also underscoring that expectations should include the possibility of anatomical improvement without large changes in vision.
Looking ahead: stronger studies and broader therapeutic goals
A major message from this systematic review is that more rigorous research is needed. Much of the current evidence comes from observational studies rather than large, multicenter randomized controlled trials. Future trials could help clarify which people with XLRS are most likely to benefit, how durable the response is, which eye drop regimen is most effective, and how OCT features relate to meaningful visual outcomes.
Topical CAIs are not a cure for XLRS, but they remain a practical and relatively low-burden approach for addressing macular changes in some patients. As research advances, studies of supportive treatments such as CAI drops can complement the broader search for therapies that address the underlying biology of XLRS. For patients and families, the review offers a clear takeaway: retinal scans may improve with treatment, and continued research is needed to turn those structural gains into more reliable improvements in vision.