Pars plana vitrectomy with internal limiting membranectomy for refractory diabetic macular edema without a taut posterior hyaloid

Background: This is a retrospective study designed to investigate the effect of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling on diabetic macular edema in eyes that do not have a taut hyaloid and have been refractory to standard laser treatment. Methods: Review of 26 eyes of 20 patients consecutively were treated with PPV with ILM peel for refractory diabetic macular edema. Eyes were included if they had been unresponsive to conventional treatment defined as at least two focal laser applications by a retina specialist. Paired t-testing was performed to determine if a change in both optical coherence tomography (OCT) measured retinal thickness and logarithm of the minimum angle of resolution (logMAR) visual acuity occurred prior to and following PPV with epiretinal membrane vitrectomy. In addition, we performed multivariate regression analysis to determine if any clinical variables predicted a change in visual acuity. Results: The mean age in the sample was 65 years ( range 29 - 81 years). The mean follow-up time was 242 days ( range 35 939). Sixteen of the 26 eyes were phakic and the remaining ten were pseudophakic. There was a statistically significant improvement of mean visual acuity from a preoperative logMAR vision of 1.0 to a best postoperative vision of 0.75 ( p= 0.016, paired t-test). Thirteen (50%) of the 26 eyes gained at least two lines of best-corrected Snellen acuity, three (11.5%) had a decline of at least two lines, and ten (38.5%) showed stable visual acuity. Regression analysis demonstrated that baseline worse visual acuity was the only clinical variable that was associated with improvement in visual acuity (beta= 0.602, p= 0.016; R 2= 28.7). Fourteen eyes had preoperative and postoperative OCT. Thirteen eyes ( 93%) had a significant decrease in foveal thickness; with an average preoperative thickness of 575 mm compared to a postoperative average of 311 mm ( t= 3.65, p= 0.002). No surgical complications were observed during the follow- up period. Conclusions: Surgery for refractory diabetic edema without a taut hyaloid is associated with a significant improvement in visual acuity and diminution of retinal thickness as measured by OCT. Further investigations are warranted to define the role of surgery in the management of persistent diabetic macular edema.