Comparison of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Thickness Values Using Spectral-Domain and Swept-Source OCT

Purpose: To compare peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thickness measurements obtained with spectral domain optical coherence tomography (SD- OCT) and swept-source OCT (SS-OCT) using an OCT-angiography scanning protocol, and their ability to distinguish among patients with glaucoma, glaucoma suspects (GS), and healthy controls (HC). Methods: Cross-sectional study of 196 eyes (81 glaucoma, 48 GS, and 67 HC) of 119 participants. Participants underwent peripapillary and macular OCT with SD-OCT and SS-OCT. Parameters of interest were average and sector-wise pRNFL and mGCIPL thickness. Inter-device agreement was investigated with Bland-Altman statistics. Conversion formulas were developed with linear regression. Diagnostic performances were evaluated with area under the receiver operating characteristic curves. Results: Both SD-OCT and SS-OCT detected a significant pRNFL and mGCIPL thinning in glaucoma patients compared to HC and GS for almost all study sectors. A strong linear relationship between the two devices was present for all quadrants/sectors (R-2 >= 0.81, P < 0.001), except for the nasal (R-2 = 0.49, P < 0.001) and temporal (R-2 = 0.62, P < 0.001) pRNFL quadrants. SD-OCT and SS-OCT measurements had a proportional bias, which could be removed with conversion formulas. Overall, the two devices showed similar diagnostic abilities. Conclusions: Thickness values obtained with SD-OCT and SS-OCT are not directly interchangeable but potentially interconvertible. Both devices have a similar ability to discriminate glaucoma patients from GS and healthy subjects. Translational Relevance: OCT-Angiography scans can be reliably used to obtain structural metrics in glaucoma patients.

Automated summary

This study compared the measurements of pRNFL and mGCIPL thickness obtained with SD-OCT and SS-OCT, and assessed their ability to distinguish among glaucoma patients, glaucoma suspects, and healthy controls. The results showed that both SD-OCT and SS-OCT detected thinning in pRNFL and mGCIPL in glaucoma patients compared to healthy controls and glaucoma suspects. The two devices demonstrated similar diagnostic abilities, and conversion formulas could be used to remove the proportional bias.