ObjectiveTo evaluate the efficacy of intravitreal injection (IVI) of expansile gas alone to treat idiopathic full-thickness macular hole (FTMH).MethodsThis is a prospective interventional case series. Twenty FTMH patients (26 eyes) who underwent IVI with expansile gas alone were enrolled in this study. There were 5 males (5 eyes) and 21 females (21 eyes), with the mean age of (59±12) years. All patients received the best corrected visual acuity (BCVA), slit lamp microscope, indirect ophthalmoscopy, fundus color photography and three-dimensional optical coherence tomography (OCT) examinations. The BCVA was measured using the international standard visual acuity chart, and the results were converted to the logarithm of the minimum angle of resolution visual acuity. The diameters of macular holes and the interface between vitreous and macular were observed by OCT (Topcon, OCT-2000). Based on the diameter, the holes were classified as small FTMH (equal or lesser than 250 μm), medium FTMH (more than 250 μm but equal or lesser than 400 μm) and large FTMH (more than 400 μm). The mean BCVA was 0.85±0.29. There were 7, 10 and 9 eyes with small, medium and large FTMH. There were 10 eyes with vitreous- macular traction (VMT). All the eyes received IVI of 0.2 ml C3F8 followed facedown positioning for 7-14 days. The follow-up ranged from 1 to 23 months. The BCVA, FTMH closure and complications were observed. If holes failed to close at 1 month after IVI, vitrectomy combined with internal limiting membrane (ILM) peeling and C3F8 tamponade would be performed for these eyes.ResultsFTMHs was able to close in 17/26 eyes (65.4%) had hole closure, failed to close in 9 /26 eyes (34.6%). All 10 eyes with VMT achieved vitreous-macula separation after IVI of gas. The eyes failed in the closure initially with IVI of gas alone, all succeed with hole closure after vitrectomy combined with ILM peeling and C3F8 tamponade. The closure rate of small (6 eyes), medium (8 eyes) and large FTMH (3 eyes) was 85.7%, 80.0% and 33.3% respectively. The diameter of FTMHs in holes-closure eyes and failed-closure eyes was (307.8±122.8), (431.6±128.4) μm respectively, the difference was significant (t=−2.407, P=0.024). VMT was found in 6 eyes and 4 eyes in holes-closure group and failed-closure group, respectively, the difference was significant (t=−2.196, P=0.038). The mean preoperative BCVA was 0.51±0.36. There was a significant difference between pre-and postoperative BCVA (t=4.758, P＜0.05). Two eyes developed local retinal detachment, which achieved hole closure and retinal reattachment after vitrectomy.ConclusionIVI of expansile gas alone is an effective way in treating FTMH with a diameter smaller than 400 μm and with VMT before surgery.