Take-home message: Analysis of eyes with and without prior vitrectomy from DRCR Protocol I showed similar results when treated with ranibizumab with prompt or deferred laser.
Reviewed by John A. Wells III, MD, FACS
West Columbia, SC—Eyes with diabetic macular edema (DME) and prior vitrectomy treated with anti-vascular endothelial growth factor (VEGF) agents appear to respond similarly to eyes with DME and no prior vitrectomy, said John A. Wells III, MD, FACS.
Dr. Wells focused on a comparison of visual and optical coherence tomography (OCT) outcomes in eyes with and without previous vitrectomy that had received ranibizumab (Lucentis, Genentech) and prompt or deferred laser treatment for DME. The research focused on anatomic and clinical outcomes from the Laser Ranibizumab Triamcinolone Trial for DME (Protocol I) within the Diabetic Retinopathy Clinical Research (DRCR) Network.
Other DRCR researchers have showed that treatment with ranibizumab, with immediate or deferred for at least 6 months laser treatment, was more effective than laser treatment alone for at least 2 years in patients with center-involved DME, Dr. Wells said.
Additionally, the vision benefits at year 1 appear to be sustained through at least a 5-year follow-up.
However, it has been suggested that in eyes with previous vitrectomy, anti-VEGF agents could have a shorter duration of action because of rapid clearance of the drug.
“There’s a lack of data to support this except in a small series of eyes treated with bevacizumab,” said Dr. Wells, in practice in Palmetto Retina, West Columbia, SC.
Post hoc exploratory analysis
This is what led to the post hoc exploratory analysis of patients with or without prior vitrectomy assigned to intravitreous ranibizumab with prompt or deferred laser. Investigators analyzed visual acuity, OCT central subfield thickness, OCT volume, and the number of injections from baseline through 3 years. There were 336 eyes in the nonvitrectomized group and 25 in the vitrectomized group.
“Baseline characteristics were balanced between vitrectomy status groups with respect to subject-level demographic, medical history, and diabetes-related factors, including age, diabetes type, pre-existing cardiovascular disease, and hemoglobin A1c,” Dr. Wells said.
That said, there were some eye-related factors that were imbalanced and that related to diabetic retinopathy and DME severity, he added.
Seven baseline characteristics may have affected the outcomes, including visual acuity, prior DME treatment, prior anti-VEGF for DME, lens status, diabetic retinopathy severity, OCT central subfield thickness and volume, and randomized assignment to the ranibizumab plus prompt or deferred laser group, Dr. Wells said.
Ultimately, the study showed that in the means-adjusted results, both groups had a substantial improvement in vision that was sustained for 3 years.
“Eyes with prior vitrectomy initially did slightly better but at 1 and 3 years, the points crossed and there was no statistically significant difference between the groups,” Dr. Wells said.
Although changes in early and sustained reduction in OCT thickness were less notable in the prior vitrectomy group, the only significant difference was at week 20. By 1, 2, and 3 years, there was no significant difference in reduction in OCT central subfield thickness or volume, he explained.
Both groups required a median of 13 injections over a 3-year period, with no additional treatment burden in the nonvitrectomized eyes. The need for injections declined from the first year in both groups to a median of 2 in the second year and a median of 1 in the third year.
However, eyes with DME require continued monitoring as the study showed DME can recur after the first year of treatment, he added.
Some study limitations include the small number of cases with vitrectomy, the fact that it is a post-hoc study, and a number of potential confounding factors.