Panretinal photocoagulation (PRP) therapy following intravitreal conbercept requires fewer injections but leads to similar visual and anatomic outcomes in people with diabetic retinopathy (DR) combined with diabetic macular edema (DME). Investigators presented these findings in research published in BMC Ophthalmology. 

PRP treatment has been the standard for patients with proliferative diabetic retinopathy (PDR) for the last 3 decades. Emerging adjunctive anti-vascular endothelial growth factor (VEGF) agents have demonstrated superior outcomes, but there is no current consensus on when PRP should be administered when combined with anti-VEGF therapy for concurrent DME. In a nonrandomized, retrospective, comparative study, researchers sought to determine whether PRP should be performed before or after intravitreal conbercept for DME. 

The cohort included a total of 58 eyes with severe nonproliferative diabetic retinopathy(NPDR) or PDR: 28 in the PRP-after group and 30 in the PRP-prior group (mean patient ages, 54.8±9.1 and 53.5±10.3 years, respectively). At baseline, no significant differences in gender ratio, age, type or duration of diabetes, HbA1c level, logMAR best corrected visual acuity (BCVA), or central subfield macular thickness (CSMT) existed between groups. 


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At 1 year, the mean number of injections received in the PRP-after group was 4.9±0.95, compared with 6.4±2.37 in the PRP-prior group. At 2 years, the PRP-after group still had a lower number of mean injections (6.4±1.5 vs 8.5±3.2). Eight and 9 patients in each group received additional peripheral laser photocoagulation. 

Over the 2-year follow-up period, both groups experienced significant improvement in visual acuity, with no significant difference in logMAR BCVA between the groups at weeks 4 and 12, year 1, and year 2. 

Optical coherence tomography demonstrated a significant relief of macular edema in both groups following treatment, although no significant differences in CSMT were noted at week 4, week 12, year 1, or year 2. 


Study limitations include the small sample size and the limitations inherent to retrospective studies. Researchers noted that randomized controlled studies with larger cohort sizes are needed to “elucidate the advantage of PRP after [intravitreal conbercept] regime.” 

The research found performing PRP after anti-VEGF injections requires fewer overall injections but also yields similar visual and anatomic outcome compared with performing PRP prior to anti-VEGF injections in patients with both DR and DME.

“The findings of this study underscore the order of anti-VEGF therapy and PRP in the treatment of naïve PRP combined with DME,” the study says. “Further investigations are needed to determine the changes in macular and peripheral vasculature, and intraocular (such as aqueous humor) VEGF levels in patients undergoing the 2 treatment regimes.”  

Reference

Zhang W, Zhao G, Fan W, Zhao T. Panretinal photocoagulation after or prior to intravitreal conbercept injection for diabetic macular edema: A retrospective study. BMC Ophthalmol. 2021;21(1):160. doi:10.1186/s12886-021-01920-8