Abstract
Purpose :
To prospectively monitor progressive changes of retinal ganglion cell (RGC) function in glaucoma suspects (GS) with clinical signs of conversion, contrasted to a group of non-converters, using Pattern Electroretinogram (PERG)
Methods :
Sixteen GS subjects (30 untreated eyes) with Humphrey 24-2 visual field test with Glaucoma Hemifield Test “Within Normal Limits”, with MD normal values <-2.00 (dB) and with suspicious optic nerve head were included in the study. Participants were observed over an average of 11.5 ± 3.7 months, during which they were tested with Diopsys NOVA PERG (Diopsys©, Inc. Pine Brook, NJ) and standard automated perimetry two times a year. Based on clinical data, two groups were formed and 9 eyes qualified as clinical converters, while 21 eyes remained as non-converters. Two-way repeated measures ANOVA were conducted as appropriate. This study was IRB approved and informed consent was signed by each subject.
Results :
Over the short course of the study, 9 eyes showed signs of conversion according to visual field and Optical coherence tomography definitions. A two-way repeated measures (mixed between-within subjects) ANOVA was used to determine the effect of time (within-subject effects) and group (between subjects effects) over the PERG repeated measures variables (MagD and MagD/mag ratio). Normality of data was assessed by the Shapiro-wilk test and no outliers greater than ± 3 standard deviations were included. There was homogeneity of variance (p> 0.05) and covariances (p>0.05), as assessed by Levene’s test of homogeneity of variance and Box’s M test, respectively. Mauchly’s test of sphericity indicated that the assumption of sphericity was met for the two-way interaction, X2(2) =8.172, p=0.379. There was no statistically significant interaction between Time and PERG parameters, confirming that MagD and MadD/Mag ratio scores did not change significantly over our 3 time points. The main effect of group showed a significant difference in PERG parameters between the converter and non-converter groups F (1,12) = 8.465, p= 0.013, partial Eta2 =0.414 for MagD/Mag Ratio and F (1,12) = 4.853, p= 0.048, partial Eta2 =0.288 for MagD
Conclusions :
Slowly converting GS patients over time demonstrate RGC dysfunction associated with increased latency. These findings are clinically significant, especially when deciding when to start treatment
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.