Clinical characteristics, risk factors, and surgical outcomes of secondary macular hole after vitrectomy.

Secondary macular hole(MH) formation after vitrectomy is rare and its risk factors and pathogenesis are not clearly understood. This retrospective study was conducted to identify the risk factors of this complication and assess outcomes at 2 tertiary centres. The primary outcomes were the clinical characteristics associated with development of secondary MH, which included the primary diagnosis for initial vitrectomy, features on optical coherence tomography, and adjuvant surgical techniques used during the initial surgery. Secondary outcomes included the change in best-corrected visual acuity(BCVA), clinical factors associated with the need for re-operations for MH closure and prognostic factors for the visual outcomes. Thirty-eight eyes out of 6,354 cases (incidence 0.60%) developed secondary MH after undergoing vitrectomy for various vitreoretinal disorders over an 11-year period, most frequently after initial surgery for retinal detachment(RD) (9 eyes) and secondary epiretinal membrane (6 eyes). The mean age was 57.1 years (range: 17.8-76.7), and the mean follow-up was 51.1 months (range: 6.8 to 137.6). Prior to secondary MH formation, development of ERM was the most common OCT feature (19 eyes, 50%), and no cases of cystoid macular oedema (CME) were observed. A greater proportion of eyes with secondary MH had long axial lengths (32% ≥26 mm vs 5% of eyes ≤22 mm). MH closure surgery was performed in 36 eyes and closure was achieved in 34 (success rate 94%, final BCVA 20/86), with ≥3-line visual gain in 18 cases. BCVA at MH onset (OR = 0.056, P = 0.036), BCVA at post-MH surgery month 3 (OR = 52.671, P = 0.011), and axial length ≥28 mm (OR = 28.487, P = 0.030) were associated with ≥3-line visual loss; a history of macula-off RD (OR = 27.158, P = 0.025) was associated with the need for multiple surgeries for MH closure. In conclusion, secondary MH occurs rarely but most commonly after vitrectomy for RD. Patients with axial length ≥28 mm and poor BCVA at 3 months post-operation may have limited visual prognosis; those with a history of macula-off RD may require multiple surgeries for hole closure.