Delayed closure of highly myopic macular holes combined with retinoschisis after inverted internal limiting membrane flap.

Purpose: To assess functional and anatomical outcomes of internal limiting membrane (ILM) inverted flap in highly myopic macular holes (HMMHs) with outer-retinoschisis (O-RS).

Methods: Retrospective interventional analysis of 19 eyes with HMMH and O-RS undergoing vitrectomy and ILM inverted flap. At baseline and every follow-up visit (1, 3, 6, 12 months and the most recent) we performed best-corrected visual acuity (BCVA, Snellen) and optical coherence tomography (OCT), collecting several parameters: minimum linear diameter (MLD), basal diameter (BD), peri-HMMH nasal and temporal retinal thickness (RT and RT), peri-HMMH nasal and temporal O-RS height (O-RS and O-RS). The ratios O-RS/ RT and O-RS/RT were defined as %O-RS and %O-RS. Postoperatively, we distinguished classic HMMH closure (n = 14) from a newly described "delayed" closure pattern (n = 5).

Results: Primary anatomical closure was obtained in 89% of eyes. Mean BCVA improved from 0.23 ± 0.17 to 0.44 ± 0.20 and 0.46 ± 0.25 at 6-months and final follow-up (p = 0.009 and p = 0.001, respectively). At every follow-up, "classic" vs. "delayed closure" did not influence BCVA (all p > 0.05). Baseline O-RS (p = 0.026), O-RS (p = 0.04), %O-RS (p = 0.04) and %O-RS (0.004), were significantly associated with the "flap closure" pattern, differently from MLD and BD. In the "delayed closure" subgroup we reported a 100% closure rate, but 65.8 ± 64.4 days after first surgery. Meantime, OCT showed an inverted ILM flap covering an area of persistent tissue loss. O-RS and O-RS progressively reduced until HMMH closure.

Conclusion: Inverted flap is useful to close HMMH with O-RS. In case of "delayed closure" pattern, watchful-waiting allows for HMMH self-sealing, without impact on BCVA.

Key Messages: What is known Inverted internal limiting membrane (ILM) flap showed favorable anatomic success in cases of highly myopic macular holes (HMMH). What is new HMMHs with outer retinoschisis (class 2c of the staging system) may close following a classic or "delayed closure" pattern. In cases of delayed closure, it took a variable range of 30-179 days to seal the HMMH but no further surgery was advisable. Post-operative BCVA improvement was not impacted at any follow-ups when comparing "delayed" and "classic" closure subgroups.