This study aimed to evaluate the protective effects of yellow-light etching anti-glare (AG) screen on Digital Eye Strain (DES) induced by prolonged video display terminal (VDT) use under dim environment, Based on the proved positive effect of the circular polarization (CP) screen, providing insights for new eye-protection strategy in the highly digital modern era. In a randomized, double-blind controlled trial, 70 eligible volunteers (diopter ≤ -6.0D; anisometropia ≤ 2.0D) were divided into AG+CP or CP only groups. Participants performed a 2-hour e-book reading task using assigned AG+CP or CP only smartphones. Subjects' severity of DES pre- and post-reading were evaluated from two aspects: the degree of dry eye symptoms and asthenopia. Dry eye symptoms indicators (OSDI, TMH, NIBUT, FBUT, CFS, Schirmer I Test) and asthenopia indicators (CVSS17, Bulbar redness, HFC) were measured and compared.

The inclusion criteria required subjects to have myopia diopter not exceeding -6.00D, hyperopia not exceeding +2.0D, astigmatism not exceeding -2.00D, anisometropia between both eyes not exceeding 2.00D. The key exclusion criteria were as follows: (1) strabismus and amblyopia; (2) used eye drops within 1 week; (3) had undergone eye surgery within 6 months; (4) worn contact lenses within the last 2 weeks; (5) had serious eye discomfort in the last 7 days; (6) breastfeeding or pregnant women and patients with severe systemic diseases, psychosis or dementia. Subjects did not know the characteristics of the smartphones they use. The subjects were asked not to use video terminals such as mobile phones within 30 minutes before the study began.

Subjects were divided into 2 groups using AG+CP or CP only smartphone provided. During the whole experiment, subjects were in a room with 2 lux-environment illuminance, screen brightness about 10nit to mimic the situation before sleep. Light source stability (working surface illuminance fluctuation) greater than 99% during the whole experiment, desktop range uniformity greater than 80%. Indoor air conditioning control temperature: 22-25 degrees Celsius, humidity: 50-70%RH. Mobile phones were placed on a fixed holder (the angle and height of the phone holder can be adjusted to ensure the suitability of participants). All subjects' eyes were 40cm away from the mobile phone screen and seated on a chair of fixed position and appropriate height. Subjects were asked to finish 2-hour reading on the specific smartphone. Reading materials are downloaded in advance to the smartphone and presented using specific reading software and settings. During the study period, subjects were not allowed to do any behavior unrelated to watching the screen for a long time (more than 1 minute). All experiments were conducted between 8:00 and 11:00 to minimize the impact of electronic screen use during the day. Ocular surface disease index (OSDI), tear meniscus height (TMH), noninvasive tear break-up time (NIBUT), Fluorescein tear break-up time (FBUT), corneal fluorescein staining (CFS) and Schirmer I test were measured to evaluate the degree of dry eye symptom. Computer vision syndrome scale 17 (CVSS17), bulbar redness and high-frequency component of accommodative microfluctuations (HFC), were identified as assessment of asthenopia. The intervention and assessments were delivered both at before and after smartphone reading by qualified clinical ophthalmologists in a hospital setting.

Inclusion Criteria:

• 1.have basic reading comprehension skills and to be older than 18 years old. 2.diopter of both eyes not exceeding -6.0D and anisometropia not exceeding 2.0D.

Exclusion Criteria:

• 1.presbyopia or decreased regulation function, 2.ocular inflammation and disease, 3.worn contact lens within 1 month, 4.history of eye surgery within 6 months, 5.lactating or pregnant woman, 6.have severe systemic diseases.