Baseline SRF was associated with rapid resolution of macular edema in both DME and RVO, but improvement in visual acuity was associated with SRF only in DME.
Baseline subretinal fluid (SRF) could have significant clinical implications on patients undergoing anti-vascular endothelial growth factor (VEGF) therapy for diabetic macular edema (DME) and retinal vein occlusion (RVO), according to new findings.1
Retrospective data showed baseline SRF was associated with rapid resolution of macular edema in both DME and RVO, but an improvement in visual acuity associated with SRF was only indicated in eyes with DME.
“To our knowledge, this study is the first to demonstrate the effects of SRF in DME and RVO simultaneously from the same tertiary retina center,” wrote the investigative team. “The prevalence of baseline SRF reported in this study allows a direct comparison between two diagnostic cohorts.
A team led by David T. Wong, MD, Department of Ophthalmology and Vision Sciences, University of Toronto, performed a retrospective study of all consecutive adult patients (≥18 years old) with DME or RVO who initiated anti-VEGF for macular edema between January 2016 and December 2017 at St. Michael’s Hospital. They included all cases with macular edema involving the fovea due to either DME or RVO on baseline OCT imaging.
Patients were stratified and subclassified into SRF versus non-SRF group based on the presence or absence of SRF on baseline OCT. All patients received intravitreal injections of bevacizumab, ranibizumab, or aflibercept. The identified primary outcomes for the study were Snellen visual acuity measured and converted to logarithm of the minimum angle of resolution (logMAR), measured up to 24 months.
The analysis included a total of 122 patients with DME and 54 patients with RVO. Baseline OCT parameters revealed patients with SRF had a significantly greater baseline CST in both the study and fellow eyes compared with eyes without SRF included in the study. At baseline, SRF was present in 27 eyes (22%) and 22 eyes (41%) in the DME and RVO subcohorts, respectively.
Results showed VA at baseline and at follow-up points after intravitreal anti-VEGF injections. Eyes with DME with SRF showed a mean VA at 24 months that was significantly higher compared with baseline (P = .016), while eyes with RVO with SRF showed a significantly higher mean VA at 12 months compared with baseline (P = .048). There were no significant differences between baseline and follow-up VA observed for non-SRF eyes in either diagnostic subcohort.
In the DME subcohort, study eyes with SRF showed a mean reduction in logMAR VA of 0.166 (1.7 Snellen chart lines) at 12 months and 0.251 (2.6 Snellen chart lines) at 24 months. These numbers were noted as significantly greater compared with the mean logMAR VA reduction of the non-SRF group. Data showed no evidence of difference in the effect of baseline SRF on VA outcomes in the RVO subcohorts.
Investigators observed a significantly greater reduction in CST in eyes with SRF compared with the non-SRF eyes in the DME subcohort, with a 25% reduction in CST at 3 months. Meanwhile, in the RVO subcohort, eyes with SRF demonstrated a 36% reduction in CST at 1 month. There was no statistically significant difference in the mean CST reduction observed between SRF and non-SRF eyes at 24 months.
The team indicated the retrospective study design allowed for variability in the choice of anti-VEGF treatment regimen and follow-up intervals. Although variable dosing had the advantage of representing real-world practice patterns, the findings were based on a smaller sample size and future studies could help elaborate these findings, according to investigators.
“Future studies may help elucidate the photoreceptor integrity associated with the presence of SRF, the mechanisms underlying the development of bilateral macular edema or bilateral SRF in patients as well as the clinical implications associated with the presence of bilateral disease at baseline,” investigators wrote. “Identifying any other patient characteristics associated with faster resolution of macular edema would be helpful for patient selection for treatment with anti-VEGF.”