Association between non-invasive tear film breakup time and corneal higher-order aberrations in eyes with tear film instability
Abstract
Background. Dry eye disease (DED) is associated with higher-order aberrations (HOAs), which are increasingly recognized as affecting both ocular comfort and visual acuity. Tear film instability reduces the regularity of the corneal surface between blinks, causing increased light scatter and reduced optical quality, even in subjects with normal best-corrected visual acuity. The aim of this study was to compare corneal higher-order aberrations in patients with suspected DED and healthy controls, and to evaluate the correlation between optical parameters and tear film stability. Methods. This comparative observational study was conducted at Ibn Al-Haythem Teaching Hospital, Baghdad, between January and December 2025. Adults with normal best-corrected visual acuity and clear corneas were recruited and classified into a dry eye group or a control group according to non-invasive first breakup time (NIFBUT) and non-invasive average breakup time (NIABUT). Corneal aberrations were measured using the SIRIUS Scheimpflug-Placido topographer-aberrometer. Results. A total of 141 eyes were evaluated: 71 (50.4%) normal eyes and 70 (49.6%) dry eyes. Sex distribution and eye laterality were comparable between groups. Tear film stability parameters were significantly lower in the dry eye group, while corneal higher-order aberration parameters, including OPD RMS, coma, spherical aberration, and trefoil, were significantly higher than in controls. Conclusion. Corneal higher-order aberrations were increased in eyes with tear film instability and lower non-invasive tear breakup time compared with controls. These results suggest that optical quality is decreased by tear film instability. Diagnosis was primarily based on non-invasive tear breakup time. The present findings should be confirmed using the complete TFOS DEWS II diagnostic criteria, including assessment of symptoms and ocular surface examination.