Enhanced structure–function relationship in glaucoma with an anatomically and geometrically accurate neuroretinal rim measurement

Purpose: To evaluate the structure–function relationship between disc margin–based rim area (DM-RA) obtained with confocal scanning laser tomography (CSLT), Bruch’s membrane opening–based horizontal rim width (BMO-HRW), minimum rim width (BMO-MRW), peripapillary retinal nerve fiber layer thickness (RNFLT) obtained with spectral-domain optical coherence tomography (SD-OCT), and visual field sensitivity.

Methods: We examined 151 glaucoma patients with CSLT, SD-OCT, and standard automated perimetry on the same day. Optic nerve head (ONH) and RNFL with SD-OCT were acquired relative to a fixed coordinate system (acquired image frame [AIF]) and to the eye-specific fovea-BMO center (FoBMO) axis. Visual field locations were mapped to ONH and RNFL sectors with fixed Garway-Heath (VF_GH) and patient-specific (VF_PS) maps customized for various biometric parameters.

Results: Globally and sectorally, the structure–function relationships between DM-RA and VF_GH, BMO-HRW_AIF and VF_GH, and BMO-HRW_FoBMO and VF_PS were equally weak. The R² for the relationship between DM-RA and VF_GH ranged from 0.1% (inferonasal) to 11% (superotemporal) whereas that between BMO-HRW_AIF and VF_GH ranged from 0.1% (nasal) to 10% (superotemporal). Relatively stronger global and sectoral structure–function relationships with BMO-MRW_AIF and with BMO-MRW_FoBMO were obtained. The R² between BMO-MRW_AIF and VF_GH ranged from 5% (nasal) to 30% (superotemporal), whereas that between BMO-MRW_FoBMO and VF_PS ranged from 5% (nasal) to 25% (inferotemporal). The structure–function relationship with RNFLT was not significantly different from that with BMO-MRW, regardless of image acquisition method.

Conclusions: The structure–function relationship was enhanced with BMO-MRW compared with the other neuroretinal rim measurements, due mainly to its geometrically accurate properties.