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

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.