gms | German Medical Science

To compare optic disc measurements obtained by two measurement modalities of optical coherence tomography.

One hundred and fifty-eight eyes of 95 Caucasian subjects were included. Mean refractive error was 0.12 ± 2.2 D. All eyes underwent optic disc assessment by optical coherence tomography (OCT3, Carl Zeiss Ophthalmic Systems-Humphrey Division, Dublin, CA, USA). Six cross-sectional scans of the disc were obtained in differing meridians. The scans were obtained by fast-scan modus (low lateral resolution, total time 1.9 sec/eye) and by normal-scan modus (high lateral resolution, total time about 15 sec/eye). Of the six scans, morphometric data of the optic disc were computed. Of all eyes, scanning laser tomographic images were obtained (HRT II, Heidelberg Engineering, Dossenheim, Germany).

Correlation coefficient (Pearson) for the two OCT methods was R = 0.92 (P<0.001) for the disc size, R = 0.98 (P<0.001) for the cup size and R = 0.88 (P<0.001) for rim area. The 95% limits of agreement (according to Bland &Altman) ranged between ±17% and ±37%. The comparison of the OCT data with the HRT data revealed higher correlation coefficients and narrower 95% limits of agreement for the fast-scan modus.

Morphometric optic disc measurements by OCT3 may be performed with the fast-scan modus. The disadvantage of the reduced lateral resolution seems to be compensated by the reduced acquisition time.