Compressive Optic Neuropathy Retrospective Comparison to Glaucoma Imaging (CORGI) Study: Correlation Between Visual Field Index and Mean Deviation in Compressive Optic Neuropathy and Open Angle Glaucoma

The visual field index (VFI) estimates the degree of visual field loss in open-angle glaucoma (OAG). VFI is expressed from 0% (perimetrically blind) to 100% (normal visual field (VF)). We explore its validity as a supplementary measure to describe VF loss in CON. We performed a retrospective cohort study of OAG and CON patients at a quaternary care center from 1 January 2013 to 6/30/2023. OAG was defined with United Kingdom Glaucoma Treatment Study (UKGTS) criteria, excluding cranial mass lesions. CON was defined by UKGTS visual field (VF) criteria, inter-eye asymmetry in retinal nerve fiber layer or macular ganglion cell layer and inner plexiform layer (mGCIPL), or intra-eye asymmetry in mGCIPL. Humphrey VF Swedish Interactive Thresholding Algorithm (SITA) size III VF protocols were used. Descriptive statistics and linear regression analyses were completed. We studied 586 patients (388 OAG, 198 CON). The OAG cohort had a median MD of −5.7 dB (IQR: −11.3, −2.9) and median VFI of 88% (IQR: 70.4, 94.4). The CON cohort had a median MD of −6.1 dB (IQR: −14.0, −3.2) and median VFI of 87% (58.0, 95.4). There was a strong correlation between VFI and MD (R2 = 0.95, p < .005) in CON and OAG (R2 = 0.96, p < .005). For each decibel decrease in MD, VFI decreased by 3.10% (p < .001) in OAG and 3.25% (p < .001) in CON. VFI is strongly correlated with MD in both CON and OAG and can be used as a proxy for MD to share disease severity with patients and non-eye care physicians.