Comparison of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Thickness Values Using...

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Diagnostics

Background:

• Accurate measurement of retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thickness is crucial for glaucoma diagnosis and management.
• Spectral domain optical coherence tomography (SD-OCT) and swept-source optical coherence tomography (SS-OCT) are advanced imaging modalities used for these measurements.

Purpose of the Study:

• To compare pRNFL and mGCIPL thickness measurements between SD-OCT and SS-OCT using an OCT-angiography protocol.
• To evaluate the ability of both OCT devices to differentiate between glaucoma patients, glaucoma suspects (GS), and healthy controls (HC).

Main Methods:

• A cross-sectional study involving 196 eyes from 119 participants (81 glaucoma, 48 GS, 67 HC).
• Peripapillary and macular OCT imaging was performed using both SD-OCT and SS-OCT.
• Analysis included inter-device agreement (Bland-Altman), development of conversion formulas (linear regression), and diagnostic performance assessment (ROC curves).

Main Results:

• Both SD-OCT and SS-OCT demonstrated significant pRNFL and mGCIPL thinning in glaucoma patients compared to HC and GS across most sectors.
• A strong linear relationship (R2 ≥ 0.81) was observed between SD-OCT and SS-OCT measurements for most quadrants/sectors, with exceptions in nasal and temporal pRNFL.
• Proportional bias between devices was identified and could be corrected using conversion formulas; overall diagnostic abilities were similar.

Conclusions:

• Thickness measurements from SD-OCT and SS-OCT are not directly interchangeable but can be made interconvertible through established conversion formulas.
• Both OCT devices exhibit comparable efficacy in distinguishing glaucoma patients from glaucoma suspects and healthy individuals.