Factors Affecting Photopic Negative Response Recorded with RETeval System: Study of Young Healthy Subjects

Purpose: To determine whether there is a significant correlation between the amplitude of the photopic negative response (PhNR) and the peripapillary retinal nerve fiber layer thickness (pRNFLT) in eyes of young, healthy subjects. Methods: We analyzed 136 eyes of 136 young, healthy subjects (89 males and 47 females; age, 20-29 years). The PhNRs were recorded with the RETeval system without mydriasis using red flashes on a blue background. PhNR amplitude was measured at two points: at 72 ms (P-72) and at the negative trough following the b-wave (P-min). Univariate and multivariable linear regression analyses were performed to identify the independent variables that were significantly correlated with P-72 and P-min. The variables included age, sex, axial length, pRNFLT, intraocular pressure (IOP), a-wave amplitude, b-wave amplitude, and pupillary area during the electroretinogram recordings. Results: The amplitudes of P-72 and P-min were significantly larger in female subjects (P = 0.021 and P = 0.001, respectively). Univariate analyses showed that PhNR amplitudes were significantly correlated with pRNFLT (P-72: r= 0.246, P= 0.004; P-min: r= 0.219, P = 0.011). Female sex was significantly and negatively correlated with P-72 (r = -0.206; P = 0.016) and P-min (r = -0.271; P = 0.001). Multivariable regression analyses showed that greater pRNFLT was an independent factor significantly associated with a larger P-72 (r = 0.283; P = 0.004) and P-min (r = 0.299; P = 0.002). Female sex was an independent factor that was significantly associated with a larger P-min (r = -0.208; P = 0.022). Conclusions: These findings indicate that PhNR amplitude is significantly associated with pRNFLT and female sex in young, healthy subjects. Translational Relevance: The amplitude of the PhNR recorded with RETeval is smaller in subjects with thinner pRNFLT not only in glaucoma patients but also in young healthy subjects.