Association Between Hair Cortisol Levels And Keratoconus: A Prospective Study

Keratoconus is a progressive corneal disorder characterized by corneal thinning, often leading to significant visual impairment. Cortisol may play a significant role in the pathogenesis of keratoconus. However, to date, no published in vivo evidence has demonstrated that elevated cortisol levels directly influence the progression of the disease. Therefore, in this prospective, single-center study, we aim to evaluate the association between cortisol levels and keratoconus severity and stability in the Jordanian population.

Purpose: To investigate the association between hair cortisol levels and keratoconus severity in a Jordanian population, exploring whether cortisol could be a potential biomarker for disease progression or stability.

We conducted a prospective, observational study at the Ophthalmology Department of King Abdullah University Hospital from March 2024 to October 2024. The study adhered to the tenets of the Declaration of Helsinki and was approved by our hospital's Institutional Review Board. Before the examination, an informed consent form was obtained from each participant.

A total of 60 participants, recruited from our clinics and aged between 18 and 30 years, were categorized into three groups: healthy controls (n=20), progressive keratoconus (n=20), and stable keratoconus (n=20).

Hair samples, consisting of 150-200 strands, were taken from the posterior vertex of the scalp, ensuring proximity to the scalp, including the proximal region. 

The frozen hair samples were then ground into a fine powder using a homogenizer. 

Cortisol concentrations were quantified using an enzyme-linked immunosorbent assay (ELISA). 

The median cortisol level was significantly higher in the Progressive Keratoconus group (987 pg/mL) compared to the Stable group (300 pg/mL, p-value <0.001). Regression analysis revealed a significant negative association between cortisol levels and stable keratoconus (β=-1.31, p<0.001). No significant association was observed for progressive keratoconus after adjustment for age and gender. Correlation analysis showed no significant associations between cortisol levels and BMI, Kmax, or Kmean. Cortisol levels also did not vary significantly across keratoconus severity categories in either eye.

Elevated cortisol levels may be associated with keratoconus progression, while lower levels appear linked to disease stability. Cortisol could serve as a potential biomarker for disease monitoring; however, further multicenter studies are needed to validate these findings and clarify cortisol's role in keratoconus pathogenesis.