Abstract
Purpose:
To determine the frequency of continued persistent DME after 24 weeks of intravitreous ranibizumab injections and to assess the impact of persistent DME on long term visual acuity in a DRCR.net randomized clinical trial comparing ranibizumab with prompt or deferred laser with laser or triamcinolone plus laser
Methods:
Eyes had best-corrected visual acuity of 20/32 to 20/320 and centered involved DME at baseline. Eyes were randomly assigned to intravitreous ranibizumab with prompt or deferred (≥24 weeks) focal/grid laser. Follow-up exams were every 4 weeks through week 52 and every 4 to 16 weeks through 3 years and included a retreatment protocol. 117 eyes (32.4%) of 361 participants randomly assigned to ranibizumab had persistent DME (central subfield thickness [CST] ≥250μm on time domain optical coherence tomography [OCT]) through the 24-week visit despite at least four intravitreous injections of ranibizumab. Cumulative probabilities of “chronic persistent DME” (failure to achieve CST <250 um and at least a 10% reduction from the 24-week visit on 2 consecutive study visits) were determined by life-table analyses
Results:
The cumulative probability of chronic persistent DME among eyes with persistent DME at the 24-week visit was 85%, 58%, and 42% (99% CI: 30% to 54%) at the 52-, 104-, and 156-week visits, respectively. Of the eyes with persistent DME at 24 weeks, the median visual acuity letter score at one year improved from randomization by 8 letters for eyes with and without chronic persistent DME at 1 year. Visual acuity improved at 3 years by a median of 5 letters and 12 letters from randomization, in eyes with and without chronic persistent DME at 3 years respectively. Among eyes with chronic persistent edema through 3 years, 43% gained ≥10 letters while 13% lost ≥10 letters from the randomization visit.
Conclusions:
These data suggest approximately one-third of eyes treated for DME with intravitreous ranibizumab have persistent central-involved DME six months after initiating treatment. Approximately half of these eyes have chronic persistent central-involved DME through 3 years. Longer-term visual acuity outcomes appear to be better among eyes without chronic persistent DME. Nevertheless, substantial (≥2 line) loss of visual acuity is uncommon at three years, even when central-involved DME persists.