Changes in Corneal Epithelial Thickness and Tear Film Stability After Carboxymethyl Cellulose Use in Young Adults with High Screen Time Exposure.

Abstract

Background: Dry eye disease (DED) is increasingly prevalent among young adults, largely driven by prolonged digital screen exposure. This study evaluated changes in ocular surface-related parameters following carboxymethyl cellulose (CMC) use in a young population with high digital screen exposure and explored baseline factors associated with anatomical change.

Methods: This prospective, single-arm interventional study enrolled 76 patients (120 eyes) aged 20-40 years with symptomatic DED and high screen time. Participants used preservative-free 0.5% CMC artificial tears four times daily for one month. Primary outcome was the change in central corneal epithelial thickness (CET) measured by Fourier-domain optical coherence tomography (OCT). Secondary outcomes included changes in non-invasive tear break-up time (NIBUT), central corneal thickness (CCT), and an analysis of predictors of anatomical improvement.

Results: One month of CMC treatment was associated with the statistically significant increase in central CET (from 52.79 ± 2.86 µm to 53.65 ± 2.92 µm; Δ = +0.86 µm, p < 0.001), with significant thickening observed across all corneal zones. Tear film stability also improved significantly, with NIBUT increasing from 6.52 ± 2.14 seconds to 7.89 ± 3.13 seconds (Δ = +1.37 seconds, p < 0.001). A strong negative correlation was found between daily screen time and baseline NIBUT (r = -0.72, p < 0.001). Binary logistic regression identified that older age within the cohort was a significant predictor of a positive anatomical response to treatment (adjusted OR = 1.15, p = 0.013).

Conclusion: In young adults with screen-time-associated DED, one month of CMC may be associated with changes in corneal epithelial thickness and tear film stability. The strong correlation with screen time underscores its role as a key risk factor.