Pars Plana Vitrectomy Efficacy in Diabetic Macular Edema Decreases Over Time

The efficacy of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling on diabetic macular edema (DME) management decreases over time, requiring additional treatment in a large number of patients, according to research published in Ophthalmologica. 

Researchers conducted a retrospective chart review of patients who underwent PPV or phacovitrectomy secondary to diffuse DME to examine the long-term effect of PPV with ILM peeling for DME. The researchers also sought to assess macular changes after surgery. 

The initial study cohort included 71 eyes from 64 patients who underwent PPV or phacovitrectomy secondary to diffuse DME. After applying exclusion criteria, 40 eyes from 37 patients were evaluated (56.8% women; mean age, 62.4±8.5 years; diabetes duration, 16.4±7.7 years; 60% nonproliferative diabetic retinopathy). Patients were grouped into 3 categories to examine macular changes following PPV: DME recurrence, DME reincrease, and DME recovery.

The cohort included 21 right eyes and 15 left eyes; 50% were phakic and 50% were pseudophakic. The mean follow-up time after surgery was approximately 51.1 months. 

In terms of surgical procedure, 80% of eyes underwent PPV alone, and 20% underwent phacovitrectomy. Twelve eyes then underwent phacoemulsification surgery approximately 6.91 months later. 

Investigators noted a significant change in best-corrected visual acuity (BCVA) following surgery (P =.001). Mean BCVA was significantly better at 2, 3, 6, 12, and 24 months and the final visit compared with baseline BCVA. Sixteen eyes had no change in BCVA, 6 eyes had a worsening of BCVA, and 18 eyes improved. 

They did note significant changes in central macular thickness (CMT) and 5 mm macular volume (5 MV) after surgery (P <.001 for both). CMT was significantly reduced at all evaluation time points compared with baseline; CMT differences between patients with and without additional treatment were not significant (P >.05).

In a subgroup analysis, investigators found that patients in each DME group had significantly decreased CMT after surgery (P =.003, P =.001, and P <.001, respectively). 5-MV also decreased in all subgroups but was significant only in reincrease DME. 

Patients in the recurrence and reincrease DME groups underwent additional treatments, including macular LPC and intravitreal injections, at similar points (a mean of 8.20 months ± 4.02 months and 8.00 months ± 4.73 months, respectively). CMT and 5 MV significantly decreased following these additional treatments. No significant differences were noted between patients who had PPV vs phacovitrectomy or between patients who were phakic or pseudophakic (P =.52 for both). 

During the postoperative period, no significant changes in intraocular pressure were noted, nor were intraoperative complications observed in any patients. Three patients experienced a postoperative transient intraocular pressure, but all were treated with topical antiglaucoma drops. 

Study limitations include the retrospective design, the small size, and the lack of a control group. 

“Based on our findings, we can state that PPV with ILM peeling for diffuse DME had an efficacy [during] earlier periods, but this effect decreases over time and additional therapy is needed in [a] considerable number of patients,” the research says. “Prospective, larger series studies are needed to better ascertain the recurrence profile of patients who underwent PPV for DME.”

Reference

Gunay BO, Erdogan G. Evaluation of macular changes in long-term period following pars plana vitrectomy with internal limiting membrane peeling for diabetic macular edema.  Ophthalmologica. Published online February 4, 2021. doi:10.1159/000514992