Overcoming segmentation errors in measurements of macular thickness made by spectral-domain optical coherence tomography.

PURPOSE

To assess the frequency and severity of segmentation errors in spectral-domain optical coherence tomography, and present an appropriate scan protocol for measuring macular thickness.

METHODS

In this study we examined 40 eyes of healthy subjects, 45 eyes with retinal pathology and 31 eyes with subretinal pathology. Patients were prospectively imaged using 12 radial scans and 3-dimensional macular cube scans by spectral-domain optical coherence tomography (3D OCT-1000; Topcon Corp., Japan) at the same sitting. Retinal segmentation errors were noted and graded using a subjective, categoric error scale to generate an error score. We compared the macular thickness measurements with and without error correction, and between the two scan protocols.

RESULTS

In this series, 63.8% of eyes (74 of 116 eyes) gave at least 1 segmentation error. Errors were more common in eyes with pathology. There was a significant difference between measurements of macular thickness with and without correcting these errors, regardless of scan protocol (P < 0.05). After error correction of both scan protocols, the macular thickness measurements obtained with the 12 radial scan protocol were equivalent to those obtained with the 3-dimensional macular cube scan protocol.

CONCLUSION

Segmentation errors were frequent on scans obtained by spectral-domain optical coherence tomography. We recommend the 12 radial scan protocol with error correction as the standard protocol for measuring macular thickness, particularly in clinical studies.