Comparative study of pars plana vitrectomy with or without intravitreal dexamethasone implant for idiopathic epiretinal membrane

Abstract

Purpose: To investigate if use of adjunctive intravitreal dexamethasone implant during pars plana vitrectomy (PPV) leads to faster visual recovery and reduction of retinal thickness in idiopathic epiretinal membrane (ERM).

Methods: In this non-randomized, comparative, interventional study 30 eyes (from 30 patients with idiopathic ERM) were enrolled. In the control group (n = 15), patients underwent 25-G pars plana vitrectomy (PPV) and ERM peeling. In the study group (n = 15), each patient underwent the same procedure as those in the control group, and also received an additional dexamethasone implant. Primary outcome after treatment was mean gain in best corrected visual acuity (BCVA), and secondary outcome was reduction in central retinal thickness (CRT). Data were analyzed using Fisher's exact test, Wilcoxon rank sum test, and two-sample t-test.

Results: The mean gain in BCVA (logMAR) from baseline at 1-month follow-up was significantly higher in the study group (median = -0.3, IQR = -0.4, -0.1) than in the control group (median = 0, IQR = -0.1, 0.3; P < 0.008). However, no significant difference in mean gain in BCVA between the two groups was detectable at the 6-month follow-up (P < 0.55). At 1-month follow-up, one and seven patients in the control and study groups gained ≥15 letters of BCVA (P < 0.05), respectively. The mean reductions in CRT at the 1-month follow-up were significantly higher in the study group than in the control group (Mean = -60 μm, SD = 92.1; P < 0.014; 95% CI = 19.75-156.54). The difference in mean reduction of CRT at 6 months was not significant (P < 0.24).

Conclusion: Adjunctive dexamethasone implant can aid faster visual recovery after PPV in idiopathic ERM, although the implants do not affect long-term gains in visual acuity.

Keywords: Idiopathic epiretinal membrane (ERM); intravitreal dexamethasone implant; pars plana vitrectomy (PPV).

Figure 1

Best corrected visual acuity (BCVA) at the 6-month follow-up. At the 1-month follow-up, mean gain in BCVA from baseline is significantly higher in the study group than in the control group (P < 0.008; 95% CI = 0.10–0.50) However, there were no significant differences in mean gain in BCVA from baseline at the 3- and 6-month follow-ups between the two groups (P < 0.10; 95% CI = -0.03–0.34, and P < 0.55; 95% CI = -0.10–0.30, respectively

Figure 2

Percentage of patients who gained ≥15 letters of best corrected vision acuity (BCVA). At the 6-month follow-up, two (13.3%) patients in the control group and seven (46.6%) in the study group gained ≥15 letters of BCVA (P < 0.05; 95% CI = 0.45–58.42). Of these, one eye from the control group and all seven eyes from the study group gained ≥15 letters at the one-month follow-up

Figure 3

Central retinal thickness (CRT) during the six months of follow-up. Mean reductions in CRT values from baseline were significantly higher in the study group at the one-month follow-up than in the control group (P < 0.014; 95% CI = 19.75–156.54). The mean reductions in CRT values were also significantly higher in the study group than in the control group at the three-month follow-up (P < 0.042; 95% CI = 3.0–139.9). The differences in mean reductions in CRT values between the two groups at the six-month follow-up, however, were not significant (P < 0.24; 95% CI = -31.3–122.9)

Figure 4

Composite picture showing OCT scans of representative patients from the control and the study group at baseline, 1 month and 6 months. (a-c) in the upper panel of the image represent the OCT scans of a 67 year old female patient from the control group with best corrected visual acuity (BCVA) of logMAR 0.6, 0.4 and 0.5 at baseline, 1 month and 6 months respectively. (d-e) in the lower panel represent OCT scans of a 70 year old female patient from the study group with BCVA logMAR 0.5, 0.2, 0.2 at baseline, 1 month and 6 month follow ups respectively