Potential pitfalls from variable optical coherence tomograph displays in managing diabetic macular edema.

To describe potential pitfalls in the use of optical coherence tomography for management of diabetic macular edema.Prospective, noninterventional case series.Review of optical coherence tomographs in 13 eyes with clinically significant diabetic macular edema from 11 consecutive patients in a private retina practice.Optical coherence tomography displays are based on 3.5-mm or 6-mm diameter circular grids that look very similar and have identical sector names but schematize different areas of the macula. The numeric outputs for the identically named sectors in the two displays do not differ significantly for retinal thickness but differ significantly in all sectors except the fovea for retinal volume because of the different areas represented by the sectors.Failure to explicitly note the scale of the optical coherence tomography display can potentially misdirect planned focal and grid laser treatment for diabetic macular edema. Failure to explicitly verify identical optical coherence tomography display scales in longitudinal studies of laser treatment for diabetic macular edema can potentially lead to errors in interpreting treatment efficacy.