• OCT CST Results Do Not Reflect Visual Acuity Changes in DME

    By Lynda Seminara
    Selected and Reviewed By: Neil M. Bressler, MD, and Deputy Editors

    Journal Highlights

    JAMA Ophthalmology, September 2019

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    Some research indicates that changes in central subfield thickness (CST) after anti-VEGF treatment of diabetic macular edema (DME) may correlate with changes in visual acuity (VA), while other studies do not support this finding. In a post hoc analysis of the DRCR Retina Network (DRCR.net) Protocol T randomized clinical trial, Bressler et al. looked at the relation­ship between these parameters and found that CST changes as noted on optical coherence tomography (OCT) account for very little of the entire variation in VA. Hence, the findings do not support OCT CST as a marker for VA changes in clinical trials of anti-VEGF therapy for DME or as a guide regarding potential changes in VA from such treatment.

    For this study, VA and OCT CST changes were compared for 652 patients who had been treated with aflibercept, ranibizumab, or bevacizumab in the randomized trial. Each patient received six monthly intravit­real injections of the anti-VEGF agent, unless success was achieved before the six-month mark. Subsequent injection or focal/grid laser photocoagulation treatment was given if needed (per protocol) to achieve stability. The main outcome measure was the association between changes in VA letter score and changes in OCT CST at weeks 12, 52, and 104 after randomization.

    The mean age of participants was 61 years (range, 54-67 years). The correlations between OCT CST changes and VA changes were 0.24 at 12 weeks, 0.31 at 52 weeks, and 0.23 at 104 weeks. The correlation coefficients of change in VA versus change in OCT CST at these time points were 0.36, 0.36, and 0.33, respectively, and were similar for each treatment. For any given change in OCT CST from baseline, there was a broad range of changes in VA from baseline to each time point.

    These results support those of laser photocoagulation studies of DME and anti-VEGF studies of other macular diseases, wherein, at best, only a mod­erate correlation was observed between VA changes and CST changes. The DRCR.net has not evaluated whether other OCT features—such as altered disorganization of the retinal inner layers—may correlate with changes in VA over time.

    Clues to reasons for the weak cor­relation between CST and VA changes are beyond the scope of this study, said the authors. However, their findings do suggest that OCT CST changes should not be used in lieu of VA changes either as a main outcome in DME trials of anti-VEGF therapy or as an indicator of the VA changes to expect from such treatment. (Also see related commen­tary by Sapna Gangaputra, MD, MPH, and Paul Sternberg Jr., MD, in the same issue.)

    The original article can be found here.