Pattern electroretinogram changes in patients with primary open-angle glaucoma in correlation with visual field and optical coherence tomography changes

Purpose: To study the pattern electroretinogram changes in primary open-angle glaucoma patients in correlation with visual field changes and optical coherence tomography measurements of retinal nerve fiber layer thickness in the peripapillary region in an attempt to evaluate the clinical value of pattern electroretinogram as an objective test of functional deficit in glaucoma. Patients and Methods: The study included 81 eyes of 81 participants: 50 primary open-angle glaucoma patients, 16 primary open-angle glaucoma suspects, and 15 controls. All subjects underwent visual field testing using 24-2 Humphrey standard automated perimetry, peripapillary retinal nerve fiber layer average thickness using the 3.4-mm circular scan of the Heidelberg OCT spectralis and pattern electroretinogram using CSO RetiMax device in accordance with the International Society for Clinical Electrophysiology of Vision guidelines. Results: We had three main groups: normal, glaucoma suspect, and primary open-angle glaucoma patients, and the last group included three subgroups: mild, moderate, and severe. There was significant difference in the visual field mean deviation, peripapillary retinal nerve fiber layer average thickness, and most pattern electroretinogram measured parameters between the three main groups and in between primary open-angle glaucoma subgroups. There was significant positive correlation between visual field mean deviation and the peripapillary retinal nerve fiber layer average thickness, P50 amplitude, and P50-N95 amplitude (p < 0.001, p = 0.018, and p < 0.001, respectively). Significant negative correlation was also found between peripapillary retinal nerve fiber layer average thickness and N95 amplitude (p < 0.001). Significant positive correlation was found between retinal nerve fiber layer average thickness and P50-N95 amplitude (p = 0.001). Significant negative correlation was found between peripapillary retinal nerve fiber layer average thickness and N95 amplitude (p = 0.001) and significant positive correlation of retinal nerve fiber layer average thickness with P50-N95 amplitude (p = 0.017) in primary open-angle glaucoma patients. Conclusion: Peripapillary retinal nerve fiber layer average thickness shows significant negative correlation with pattern electroretinogram N95 amplitude and a significant positive correlation with P50-N95 amplitude. In combination with optical coherence tomography, pattern electroretinogram can be used to objectively assess functional loss in glaucoma.