LAUSR

Introduction To investigate the influence of myopia on outcomes of visual evoked potential. Methods Twenty subjects (40 eyes), whose visual acuity was around 0.1 before correction and more than 0.8 after correction, were chosen from our hospital refraction center starting from October, 2015 to February 2016. After receiving the LASIK (laser-assisted in situ keratomileusis), all of them were given the VEP examination with electromyography & evoke potential equipment (MED-9200K, Japan). The PRVEP setup is in accordance with International 10–20 system standard (reference electrodes at Fz, record electrode at O1,Oz,O2, ground electrode at FPz) and the subjects sit in front of pattern reversal stimulator with a horizontal distance of 75 cm from their eyes to screen, received full field stimuli. When conducting examination, the subjects were asked to stare at the visual marker in the screen center and avoid the frequent eye blinking and movement, while the pattern reversal stimuli was set to rotate 2 turns per second. Before and after the visual correction, every naked eye was checked 2 times at least with an interval of 3 min and an increment of 100 times. Then two similar results were overlaid to assess the consistency of waveform in hope of enhancing the precision of outcomes. After recording, the comparison between unaided and corrected visual acuity was performed to evaluate their corresponding P100 difference of latent period. Results The latent value of wave N75, P100, N145 of unaided eyes of 20 subjects (40 eyes) were improved significantly compared with those after visual correction. Conclusion P100, with minor variation and reliability, can be recorded in all healthy subjects and has been taken as the unique and dependable wave component for analysis of PRVEP. Additionally, P100 peak latency is less susceptible to the degree of attention and visual acuity and consequently become the crucial indicator of clinical assessment. The P100 latency of unaided eyes was considerably longer than that of corrected eyes, which relatively approximate to normal value. Conclusively, our data has shown that visual acuity can exert a substantial influence on P100 latency and the subjects with myopia are advised to correct their visual acuity more than 0.8 when receiving VEP, otherwise this will contribute to false positive results and negatively affect clinical diagnosis.