Correlation between Structural and Functional Changes in Glaucoma Patients Using Optical Coherence Tomography and Pattern Electroretinogram

Abstract
Background: To study the correlation between peripapillary retinal nerve fiber layer (RNFL) thickness measured with Optical Coherence Tomography (OCT) and pattern electroretin-ogram (pERG) parameters in primary open-angle glaucoma (POAG) patients.
Aim of Study: To study the correlation between peripap-illary RNFL thickness measured with OCT and pERG param-eters in POAG patients.
Patients and Methods: Fifty eyes of 50 patients diagnosed with POAG and 15 eyes of 15 normal subjects as control group, were enrolled in a prospective comparative study. The eyes in the POAG group were further subdivided into mild, moderate, and severe subgroups. All eyes had visual field testing using 24-2 Humphery standard automated perimetry, peripapillary RNFL average thickness using the 3.4mm circular scan of the Heidelberg OCT spectralis and pERG using CSO RetiMax device in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) guidelines.
Results: There were significant differences in the visual field mean deviation (VF MD), peripapillary RNFL average thickness & some pERG measured parameters (N95 latency & P50-N95 latency) between normal and POAG eyes as were as among the three subgroups of POAG. Significant correlation was found between peripapillary RNFL average thickness and N95 amplitude (p<0.001), P50-N95 amplitude (p=0.002), N95 latency (p=0.034) & P50-N95 latency (p=0.045). We found significant correlation between peripapillary RNFL average thickness and N95 amplitude (p=0.001), P50-N95 amplitude (p=0.017) in POAG patients.
Conclusion: Peripapillary RNFL average thickness is significantly correlated with pERG N95 amplitude & P50- N95 amplitude. In combination with OCT, pERG can be used to objectively assess functional loss in glaucoma.