Abstract
Purpose :
To compare the glaucoma diagnostic capabilities of corneal parameters previously associated with glaucoma against standard structural and functional variables.
Methods :
All subjects were participating in a prospective, longitudinal glaucoma research study at the Albuquerque VA Medical Center and were diagnosed primary open-angle glaucoma (POAG) or glaucoma suspect (GS). POAG eyes had glaucomatous optic neuropathy with repeatable visual field loss on standard automated perimetry (SAP) while GS eyes had IOP>21mmHg, suspicious optic nerve appearance, or both but no repeatable visual field loss on SAP. Right eyes were analyzed unless that eye did not meet diagnostic criteria and then the left eye was analyzed. Mean values were generated from two or more consecutive visits for those clinical parameters associated with significant inter-visit variability. Receiver operating characteristic (ROC) analyses were employed to quantify and compare diagnostic capabilities between several clinical variables.
Results :
Of the 99 POAG eyes included in this study, visual field mean defect (MD) was -5.65 ±4.79dB and retinal nerve fiber layer thickness (RNFL) was 68.5 ±12.5 µm. Of the 87 GS eyes, MD was -0.01±0.13dB and RNFL was 90.6±10.1µm. Mean intraocular pressure (IOP), central corneal thickness (CCT), corneal hysteresis (CH), cup/disc ratio (CDR), visual field mean defect (MD), and retinal nerve fiber layer thickness (RNFL) were all significantly different between diagnostic groups (ANOVA, all p<0.005). Area under the ROC curve was significantly greater for RNFL, MD, and CDR compared to CCT, CH, and IOP. At 95% specificity, sensitivity (with cutpoints) for RNFL, CH, and CCT were 67% (73.5 µm), 30% (<6.9mmHg), and 8% (<493 µm) respectively.
Conclusions :
Although mean values of CCT and CH were significantly lower in glaucomatous versus glaucoma suspect eyes, their overall diagnostic performance was poor compared to CDR, RNFL, and visual field parameters. These findings suggest that CCT and CH have minor supplemental value for identifying glaucoma, and are primarily useful only when these parameters are either very low or very high.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.