# The association between upper tarsal conjunctiva appearance and corneal biomechanical weakening in refractive surgery candidates

## TL;DR

This study found that roughness in the upper tarsal conjunctiva may be linked to weaker corneal biomechanics in people considering refractive surgery.

## Contribution

The study identifies a novel association between conjunctival roughness and corneal biomechanical weakening in refractive surgery candidates.

## Key findings

- Conjunctival roughness was positively correlated with the deformation amplitude ratio, indicating biomechanical weakening.
- No significant association was found between conjunctival redness and corneal biomechanics.
- Changes in biomechanics were not sufficient to affect the Corvis Biomechanical Index.

## Abstract

Current evidence suggests allergic conjunctivitis and contact lens use may affect corneal biomechanics, but the relationship between conjunctival changes and biomechanical abnormalities remains unclear. This study aimed to determine whether upper tarsal conjunctival roughness and redness are associated with corneal biomechanical weakening in refractive surgery candidates without ectatic corneal disease. Conducted at Chiang Mai University LASIK Center between July 2023 and January 2024, conjunctival roughness and redness were graded using the Institute for Eye Research (IER) scales, while corneal biomechanics were assessed through Corvis parameters. The study included 434 eyes from 217 participants (70.5% female), with a mean age of 33.4 years (SD 8.3). Ocular allergy was reported by 23.0% (50/217) of participants, and 54.4% (236/434) had a history of contact lens use. The median conjunctival roughness score was 2 (IQR 0, 5). Conjunctival roughness score was positively correlated with biomechanical indices, particularly the deformation amplitude (DA) ratio (coefficient 0.009, 95% confidence interval 0.001 to 0.017, p = .04), suggesting weakened biomechanical property. No significant association was found between conjunctival redness and corneal biomechanics. In conclusion, upper tarsal roughness may associate with biomechanical weakening of the cornea, though these changes were insufficient to significantly affect the Corvis Biomechanical Index (CBI).

The online version contains supplementary material available at 10.1038/s41598-025-00122-2.