Abstract
Purpose :
To assess the associations between ssPERG parameters and SD OCT measurements of macular thickness, RNFLT and OHN anatomy in preparametric glaucoma patients with normal visual field tests and suspicious ONH appearances.
Methods :
Ten glaucoma suspect subjects with repeatable normal 24-2 Humphrey visual tests were enrolled, and were tested with Diopsys NOVA device and Cirrus SD OCT. Associations were determined between MagnitudeD/Madnitude Ratio from ss PERG tests and SD OCT Average ganglion cell layer-Inner plexiform layer thickness, macular thickness, RNFLT, neuroretinal rim area, Disc area, average C/D ratio and vertical C/D Ratio. Statistical analysis included descriptives, partial correlations and linear stepwise regression analyses. All participants signed an IRB approved informed consent.
Results :
Results of 10 patients (mean age =55.4 years, SD = 16.9 years) and 20 eyes with normal visual fields (Mean MD =-0.091± 1.12 dB). CS MagD/Mag Ratio was strongly associated with volume cube (r= 0.561, p=0.001) and thickness average cube (r=0.569, p=0.009); with RNFLT (r=0.626, p=0.003) and with average GCP-IPL thickness (r=0.659, p=0.002). CSF MagD/Mag Ratio was strongly associated with volume cube (r= 0.633, p=0.003) and thickness average cube (r=0.641, p=0.002); with RNFLT (r=0.814, p<0.001) and with average GCP-IPL thickness (r=0.695, p=0.001).
In the linear regression analysis to predict CS MagD/Mag Ratio, after controlling for age (1st step), IOP (2nd step), average GCP-IPL (3rd step) uniquely explained 37.2% of the variance (B= 0.019, 95%CI: 0.007 - 0.031, p=0.008). Similarly, to predict CSF magD/Mag Ratio, average GCP-IPL thickness explained 42.4% of the variance (B= 0.018, 95% CI: 0.006-0.03, p=0.01). In a third model to predict RNFLT, after controlling for age, IOP, average GCP-IPL thickness explained 51.2% of the variance (B=0.610, 95% CI: 0.226-0.994, p= 0.006). No significant correlations were found between ss PERG parameters and ONH anatomy parameters.
Conclusions :
Significant association was found between ss PERG and average GCP-IPL thickness , macular thickness and RNFLT, suggesting that ss PERG detects not only retinal ganglion cells dysfunction in the macula, but it assesses RNFL health as well. We conclude that glaucomatous insult begins with early RGC dysfunction in the macula, and then in the RNFL secondary to the RGC death, and prior to the ONH damage.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.