Diabetic Macular Edema Treated with Anti-Vascular Endothelial Growth Factor: Considerations Related to Nonimprovers

To investigate central subfield thickness (CST) nonimprovers' anatomic response in macular areas outside the central subfield and the time course of this response. Furthermore, to investigate the relationship between peripheral improvement and visual acuity.

Retrospective study.

A total of 566 eyes in 566 patients with center-involved diabetic macular edema who initiated intravitreal treatment with ranibizumab between January 1, 2011 and December 31, 2013 in the Greater Copenhagen Region. Follow-up was completed at 2 years.

Patients were initially grouped as CST improvers and CST nonimprovers. The CST improvers had a ≥10% reduction in CST on ≥1 visit as opposed to CST nonimprovers with <10% reduction in CST on all visits. The CST nonimprovers were divided into peripheral improvers with ≥10% reduction in retinal thickness in ≥1 subfield outside the central subfield on ≥1 visit and overall nonimprovers with <10% reduction in retinal thickness in all subfields on all visits. Thus, 3 response groups were defined on the basis of retinal thickness change during the first year of treatment: CST improvers, peripheral improvers, and overall nonimprovers.

The OCT total volume and best-corrected visual acuity (BCVA).

A total of 79 of 566 patients (14%) were CST nonimprovers, consisting of 45 (57%) peripheral improvers and 34 (43%) overall nonimprovers. For CST improvers and peripheral improvers, total retinal volume decreased from baseline to 3 months: -3.93% per month (95% confidence interval [CI], -4.15 to -3.71) and -2.00% per month (95% CI, -2.74 to -1.26), respectively. Overall nonimprovers' total retinal volume remained unchanged from baseline to 3 months: 0.13% per month (95% CI, -1.02 to 0.76). From 3 to 24 months, the decrease in total retinal volume was not significantly different among the 3 groups. Improvement in BCVA was not significantly different among the 3 groups from baseline to 3 months (P = 0.28). After 3 months, BCVA remained stable.

Some 57% of CST nonimprovers experience a decrease in retinal volume outside the central subfield within the first 3 months of treatment and then remain stable in central and peripheral subfields. However, peripheral improvement did not influence BCVA, and development of BCVA was similar for the response groups. Our study shows that re-treatment criteria should be based on BCVA stability for CST nonimprovers rather than a main reliance on OCT parameters.