Corneal biomechanical features in patients with ankylosing spondylitis

ABSTRACT Purpose: To evaluate the corneal biomechanical features and central corneal thickness in ankylosing spondylitis patients and to evaluate correlations of these parameters with disease activity. Methods: The study included 51 patients diagnosed with ankylosing spondylitis (mean age, 40.80 ± 13.15 years; range, 18-72 years) and 34 age- and sex-matched healthy controls (mean age, 42.00 ± 12.32 years; range, 18-60 years). All underwent a complete ophthalmological and physical examination, including visual acuity testing and biomicroscopic anterior and posterior segment examinations. Corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure, and corneal compensated intraocular pressure were evaluated with an ocular response analyzer, and the central corneal thickness was measured with Sirius® corneal tomography. The Bath Ankylosing Spondylitis Disease Activity Index, Functional Index, and Metrology Index scores were recorded. Results: In the ankylosing spondylitis patients, the mean disease duration was 7.73 ± 6.05 (range, 1-30) years. There was no statistically significant difference between the patients and controls in the corneal biomechanical features. The Goldmann-correlated intraocular pressure and corneal compensated intraocular pressure both showed positive correlations with age (p=0.003 and p=0.001, respectively). There was a negative correlation between corneal hysteresis and disease duration (p=0.002), and between central corneal thickness and the Bath Ankylosing Spondylitis Metrology Index score (p=0.003). Conclusion: This study demonstrated a significant negative correlation between corneal hysteresis and disease duration in ankylosing spondylitis patients. Furthermore, the central corneal thickness value decreased with an increase in Bath Ankylosing Spondylitis Metrology Index score, which may result in an underestimate of intraocular pressure readings and thus an inaccurate risk assessment of glaucoma.