Previous studies have suggested that ocular inflammation—a key driver of dry eye—could lead to stromal change and weakening of the corneal tissue. This has led researchers to suggest that DED has an impact on corneal biomechanics, which prompted this current study to evaluate the association between symptoms and signs of DED with corneal biomechanics parameters.

A total of 81 participants without history of ocular hypertension, glaucoma, keratoconus, corneal edema, contact lens use, diabetes or ocular surgery took part. All were evaluated for symptoms and signs of DED using the OSDI questionnaire, tear film break-up time (TBUT), and conjunctival and corneal staining Schirmer test. Corneal biomechanical parameters were obtained using the Corvis ST device.

Among 10 corneal biomechanical properties measured, eight parameters were associated with either symptoms or signs of DED. “The increase in severity of DED was associated with less stiffness of cornea in both low and normal tear production,” the authors concluded in their study. “No difference in corneal biomechanics between low and normal tear production was detected. In participants with low tear production, the increase in OSDI scores and conjunctival staining scores were associated with more compliant cornea. Furthermore, the lower Schirmer test was associated with the more compliant cornea in participants with normal tear production.”

Additionally, symptoms and signs of DED except TBUT were correlated with at least among ten corneal biomechanical parameters.

“After an air impulse generated by Corvis ST, the patients with more severe dry eye symptoms showed smaller concavity radius,” the authors explained in their study. Those with higher conjunctival staining scores demonstrated lower second applanation velocity, ones with higher corneal staining exhibited longer length of flattened cornea at second applanation and patients with lower tear production displayed a higher speed of corneal apex at first applanation and shorter first applanation time. The authors noted with interest that most of the biomechanical variations in dry eye patients also “were consistent with the alteration that was found in patients with keratoconus.”

The authors add that corneal biomechanics might serve as new parameters for categorizing dry eye severity.

Satitpitakul V, Taweekitikul P, Puangsricharem V, et al. Alteration of corneal biomechanical properties in patients with dry eye disease. PLOS One. Epub ahead of print.