PURPOSE: To investigate hair cortisol concentration (HCC), a biochemical correlate of chronic psychological stress, and its relationship to the progression of keratoconus.

METHODS: Eighty-six participants were included in this prospective observational study (32 patients with progressive keratoconus, 32 patients with stable keratoconus, and 22 healthy controls). Hair cortisol concentrations were determined from 3-cm hair strands collected near the scalp from patients and controls as an index of cumulative cortisol secretion during the 3-month period prior to hair sampling. In addition, self-reported chronic stress was assessed using the Trier Inventory for the Assessment of Chronic Stress screening scale.

RESULTS: Patients with progressive keratoconus exhibited higher hair cortisol concentrations (mean value: 29.11 pg/mg; 95% confidence interval [CI]: 22.13 to 38.28) than patients with stable keratoconus (mean value: 15.88 pg/mg; 95% CI: 12.25 to 20.65; P = .007) and healthy controls (mean value: 16.98 pg/mg; 95% CI: 12.30 to 23.44; P = .049). There were no significant differences in hair cortisol concentrations between healthy controls and patients with stable keratoconus (P = .991). Group differences were not affected by relevant covariates (body mass index, age, or sex).

CONCLUSIONS: This study shows that increased hair cortisol concentration seems to be associated with the progression of keratoconus. There are a variety of causes of increased hair cortisol concentration. [J Refract Surg. 2017;33(6):383-388.].