Segmentation error in Stratus optical coherence tomography for neovascular age-related macular degeneration

To describe the rate of automated segmentation error in Stratus optical coherence tomography (OCT) scans in consecutive patients with neovascular age-related macular degeneration (nAMD) receiving treatment and to investigate the effect of the segmentation error on automated retinal thickness measures and whether further imaging reduces the rate of segmentation error.

A retrospective analysis of fast macular thickness map (FMTM) protocol OCT scans of 50 eyes of 50 consecutive patients with nAMD. Each line scan was analyzed for segmentation error with manual measurement of the center-point retinal thickness allowing calculation of the percentage error in automated thickness. OCT scanning was repeated to overcome segmentation error.

Segmentation error was detected in 45 (90%) of the 50 patients with 37 (74%) patients having an error affecting the central 1-mm subfield. Scan sets with a high central segmentation error score (two or more line scans affected of six) had a significantly greater error in automated center-point retinal thickness than scan sets with a low error score (20% compared with 3%, P < 0.000005). Central subfield segmentation error persisted in 30 (60%) patients despite repeat scanning.

There is a high rate of segmentation error in OCT scans of patients with nAMD who are undergoing treatment, leading to errors in automated central retinal thickness measurement. The authors recommend manual measurement of central macular thickness when two or more line scans are affected by segmentation error in the central 1-mm subfield. Repeated scanning reduced the rate of error but did not eliminate the problem.