Ocular Surface Damage and Blink Dynamics Associated with High-intensity Smartphone Use

To investigate the effects of two hours of intensive smartphone use on the ocular surface and evaluate contributing factors, including task type, viewing distance, exposure duration, and blinking dynamics.

A within-subject interventional study was conducted in 21 healthy adults. Participants performed video viewing and gaming tasks at viewing distances of 20, 30, and 40 cm for two consecutive hours under controlled environmental conditions. Blink behavior was recorded using front-facing camera and Visual Analog Scale (VAS) were collected every 30 minutes. Comprehensive assessments including computer vision syndrome questionnaire, functional visual acuity, accommodative function, tear meniscus height, non-invasive tear breakup time, bulbar redness, fluorescein breakup time, and corneal fluorescein staining, were performed at baseline and immediately after screen exposure.

Intensive smartphone use exacerbated subjective symptoms, reduced visual function, and impaired tear film stability. Game task and near-distance viewing were associated with greater symptom aggravation, visual impairment and tear film instability within the same participants (P < 0.001). During gaming, blink frequency remained persistently reduced, while incomplete blink rate (IBR) increased to approximately 60%. IBR rose progressively and correlated positively with corneal fluorescein staining (OR = 1.19, P = 0.01). A digital eye strain prediction model based on VAS scores demonstrated a strong fit (R² = 0.854).

Two hours of intensive smartphone use, particularly during gaming tasks, significantly alters blinking behavior, including reduced blink frequency and increased IBR, which may contribute to ocular surface damage. These changes may reflect a failure of compensatory blinking under high visual load.