Comparison of Retinal Nerve Fiber Layer Imaging by Spectral Domain Optical Coherence Tomography and Scanning Laser Ophthalmoscopy

Objective To compare the area and the angular width of localized retinal nerve fiber layer (RNFL) defects imaged by confocal scanning laser ophthalmoscopy (CSLO) and optical coherence tomography (OCT) and to evaluate their agreement. Design Cross-sectional study. Participants Fifty-one eyes of 41 glaucoma patients. Methods Sixty-one distinctive, localized RNFL defects (17 superior and 44 inferior RNFL defects) detected in RNFL photographs imaged by a CSLO were identified. These patients underwent RNFL imaging with a spectral-domain OCT. The RNFL thickness deviation maps (50×50 pixels) generated by the OCT revealed the locations of abnormal RNFL thicknesses with abnormal pixels denoted in red (RNFL thickness less than the lower 99% normal distribution) or yellow (RNFL thickness less than the lower 95% normal distribution). The RNFL thickness deviation maps were aligned and overlaid with the corresponding CSLO RNFL photographs. The area and the angular width of RNFL defects from the corresponding retinal regions in the CSLO RNFL photographs and the OCT RNFL thickness maps were measured and compared. Their agreement was analyzed with the Bland-Altman plot. Main Outcome Measures The area and the angular width of RNFL defects and the agreement of RNFL defects measurements between OCT images and CSLO RNFL photographs. Results The area and the angular width of RNFL defects measured with the CSLO RNFL photographs were 1.11±0.57 mm2 and 23.80±10.38°, respectively, which were significantly smaller than those measured by the OCT RNFL thickness deviation map when abnormal RNFL thickness was defined as less than the lower 95% centile ranges (2.27±0.92 mm2 and 74.16±28.74°, respectively; both P