Fig 1. Comparison of corneal nerve parameters in asymptomatic and symptomatic patients based on erectile function score (a & b) and comparison of total and free testosterone levels between asymptomatic and symptomatic patients based on erectile function (c & d), frequency of sexual thoughts (e & f), and frequency of morning erections (g & h).

CNFL and CNFD are both significantly lower in symptomatic compared to asymptomatic patients with erectile dysfunction (a & b). Data are presented as mean and standard deviation for normally-distributed variables and median and interquartile range for non-parametric variables. Erectile function questionnaire response categories: 1: always able to keep erection good enough for sexual intercourse, 2: usually able, 3: sometimes able, 4: never able. Abbreviations: CNFD, corneal nerve fibre density; CNFL, corneal nerve fibre length. p<0.05 is considered statistically significant.