Vitrectomy results in diabetic macular oedema without evident vitreomacular traction.

PURPOSE: To determine the effectiveness of vitrectomy in eyes with diabetic macular oedema without evident traction from a thickened vitreous membrane.
METHODS: Twenty-one consecutive eyes from 19 patients with diabetic macular oedema that had undergone vitrectomy were analysed retrospectively. All eyes had an attached posterior hyaloid membrane in the macular region, but without thickening and without evident traction on the macula. A standard pars plana vitrectomy with the creation of a posterior vitreous detachment was performed.
RESULTS: Median duration of macular oedema at the time of vitrectomy was approximately 11.0 months (range 2-36 months). The median preoperative best-corrected visual acuity of 0.08 (range hand motions/0.003 to 0.4), improved by 5 lines to a median final postoperative best-corrected visual acuity of 0.25 (range 0.025-0.5) (P = 0.001). Seven eyes without preoperative macular photocoagulation had a median visual acuity improvement of 77%, range 32-400%, while 12 eyes with preoperative macular laser treatment had a median visual acuity improvement of 14.8%, range 0-66.1% (P = 0.02, CI 95%, after multivariate regression analysis). In all 21 eyes, macular oedema was no longer visible on microscopic examination after a median period of 3.0 months (range 1-9 months) after vitrectomy.
CONCLUSIONS: In eyes with diabetic macular oedema without evident macular traction from a thickened vitreous membrane, vitrectomy resulted in the resolution of macular oedema, with an improvement in visual acuity in the majority of cases. Eyes without preoperative macular photocoagulation had a significantly higher percentage visual improvement than eyes without preoperative macular laser treatment. A randomised controlled prospective trial of primary vitrectomy versus macular photocoagulation is needed to determine the role of vitrectomy as treatment modality for diabetic macular oedema.