[Correlation between diameter and primary closure rate by internal limiting membrane peeling and air tamponade in large idiopathic macular holes].

Objective: To analyze surgical outcomes by internal limiting membrane peeling and air tamponade in large idiopathic macular holes (IMHs) and the correlation between the minimal diameter and the primary closure rate. Methods: Retrospective study. A total of 282 patients (300 eyes) with IMHs larger than 400 µm who underwent vitrectomy and internal limiting membrane peeling in Beijing Tongren Hospital from July 2015 to January 2019 were enrolled, including 56 males (61 eyes) and 226 females (239 eyes) with an medium age of 65(62, 68) years. Before July 2016, gas tamponade was applied while after that, air tamponade was used. The minimal diameter of the IMH was measured. IMHs were divided into intervals every 50 µm by minimal diameter, and the primary closure rate of the two tamponades were compared between intervals by Chi-square test. The receiver operating characteristic (ROC) curve was drawn to show the correlation between the minimal diameter and the primary closure rate by air tamponde. Results: The mean minimal diameter of all the IMHs was (615.7±126.0)µm. In general, the primary closure rate was 91.7% (275/300), and the BCVA at last visit (0.5(0.3, 0.7)) improved significantly (P<0.001) comparing to the preoperative one (0.1(0.05, 0.2)). A total of 187 eyes with air tamponade exhibited a primary closure rate of 88.2%, which was significantly lower (P=0.005) than that with gas tamponade (97.3%). For IMHs with air tamponade, the optimal closure rate was 100% among all intervals; from the interval of (650, 700)µm on, the primary closure rates of every interval gradually decreased and were significantly lower than the optimal one (P<0.05) respectively; the ROC curve revealed that IMHs larger than 664.5 µm tended to exhibit a smaller chance of primary closure. For IMHs ≤650 µm, the two tamponades exhibited comparable primary closure rate (96.1% for air, 100.0% for gas, P=0.17), while for IMHs>650 µm, air tamponade (71.2%) presented significantly lower rate (93.5% for gas, P=0.002). IMHs ≤650 µm exhibited significantly better BCVA compared to those larger (P<0.01), no matter which tamponade was applied. In IMHs ≤650 µm, BCVA exhibited no significant difference between the two tamponades, so as in IMHs>650 µm. Conclusions: For IMHs with air tamponade, the minimal diameter is closely related to both the primary closure rate and the postoperative BCVA. IMHs>650 µm exhibited evidently poorer anatomical and functional outcomes compared with those ≤650 µm, which suggested that maybe other techniques for the internal limiting membrane could be applied to improve surgical outcomes for these large IMHs. (Chin J Ophthalmol, 2019, 55:739-746).