Abstract
Purpose
To evaluate the difference in ganglion cell layer (GCL) thickness on optical coherence tomography (OCT) and wave forms on pattern electroretinography (PERG) among glaucoma suspects and healthy controls
Methods
An analytical, cross-sectional study was done on 100 eyes of 50 subjects, equally divided in the glaucoma suspect and control group. Subjects with an asymmetrically increased vertical cup-to-disc ratio and without any perimetric change were taken as suspects, and subjects with normal findings were taken as controls. GCL thickness was evaluated on spectral domain OCT at 3mm, 3.45mm, and 6mm centering the foveola, and P50, N95 wave forms were recorded according to the standard PERG protocol.
Results
In this study, we observed that the average GCL thickness is significantly less in glaucoma suspects at 3.45mm (p = 0.045) and at 6mm (p < 0.001) circle zone. On PERG, P50 amplitude was significantly low in glaucoma suspects in comparison to controls (p = 0.007). There was significantly increased implicit time for both P50 and N95 in glaucoma suspects (p < 0.001). For N95 amplitude, a non-significant (p = 0.127) difference was observed among the two groups. At 3.45mm, average GCL thickness showed a weak negative correlation with N95 implicit time (r=-0.286, p = 0.044), a weak positive correlation with P50 amplitude (r = 0.349, p = 0.013), and at 6 mm, a weak positive correlation with P50 amplitude (r = 0.311, p = 0.028) in glaucoma suspects.
Conclusions
Thickness analysis of GCL alone can help in the structural assessment of preperimetric glaucoma. PERG can be used as a valuable tool for the detection of ganglion cell dysfunction, even before cell loss.