Abstract
Purpose:
Static and dynamic contrast sensitivites were assessed and compared with steady-state ‘pattern electroretinography ratio’ (‘PERG ratio’) in open angle glaucoma (OAG) patients. Their efficacy in determination of retinal ganglion cell (RGC) functional damage was compared.
Methods:
Overall 36 (24 female, 12 male, mean age: 55.94 ± 16.55) suspected OAG patients were enrolled in the study. Their records were compared to the records of 36 age matched control subjects (22 female 14 male, mean age: 32.19 ± 16.64). Due to the wide age range, subjects were divided in groups of above and below 40 years of age. Inclusion criteria were (i) vertical and horizontal optic disc cupping ratio > 0.4-0.5, (ii) specific visual field defects and (iii) peripapillary alterations. Static and dynamic (frequency: 8.56 rev/sec) contrast sensitivities (CS) were measured at spatial frequencies of 0.48, 1.19, 1.91, 2.87, 3.58, 4.78, 5.73, 7.17, 14.34 cyc/deg by Neuroscientific Venus® 1020. Electrophysiological examinations were performed with Retiport Science 4.9.8.9. Program®. Steady-state PERG (constant frequency: 4.28 Hz) response amplitude to 0.8° checks and the amplitude to 16° checks were recorded and their ratio, the ‘PERG ratio’ was calculated. ANOVA on Ranks and Spearman correlation were applied (SigmaStat® 3.5).
Results:
Above 40 years of age, significant differences were revealed in all dynamic and static spatial frequencies of CSs between suspected OAG and control groups (p<0.05). Below 40 years of age, however, no significant differences were found. There was significant difference in ‘PERG ratio’ between controls and suspected OAG patients in both age groups (<40 years: 1.1 vs. 0.87, >40 years: 0.98 vs. 0.76; p<0.001; ANOVA on ranks). Both static and dynamic CS correlated with ‘PERG ratio’ at all spatial frequencies, but correlations were stronger at dynamic CSs (r=0.34-0.46 vs. 0.42-0.68 p<0.001, Spearman correlation).
Conclusions:
In our subjects, dynamic CS showed stronger correlation to ‘PERG ratio’ than static one, which raises the possibility its higher value in determination of glaucomatous-type functional RGC damage. ‘PERG ratio’ and dynamic CS may help establishing the diagnosis of glaucoma in addition to the widely available perimetry. Further examinations are needed to confirm our findings.
Keywords: 531 ganglion cells •
478 contrast sensitivity •
509 electroretinography: clinical