**Background:** Excessive smartphone use (SPU) is a growing public health concern, linked to various health issues including dry eye disease (DED). DED is a multifactorial ocular surface disease affecting 5–50% of the global population, causing discomfort, visual disturbance, and economic burden. While visual display unit (VDU) use is a known risk factor for DED, the specific relationship between SPU and DED had not been systematically reviewed. This review aimed to synthesize evidence on the association between SPU and DED.
**Methods:** The review followed PRISMA guidelines and searched Medline, EMBASE, CINAHL, and PsychINFO from inception to January 15, 2021, without language or study design restrictions. Search terms combined smartphone-related terms (e.g., smartphone, cell phone, mobile phone) with DED-related terms (e.g., dry eye, keratoconjunctivitis sicca, meibomian gland dysfunction). Reference lists and citations were hand-searched. Eligible studies included any epidemiologic design examining the relationship between daily SPU duration (in hours) and DED measured by validated self-reported tools or objective eye examination. Studies involving participants with known DED risk factors (e.g., eye drops, diabetes, thyroid eye disease) were excluded. Two reviewers independently screened, extracted data, and assessed quality using an adapted Newcastle-Ottawa Scale for cross-sectional studies and the methodological index for non-randomized studies.
**Key Results:** Of 92 citations identified, 4 studies met inclusion criteria (total n=1599). All were conducted in South Korea (2014–2018): 3 cross-sectional studies and 1 nonrandomized trial. Two studies included school children (ages 7–12), one included college students (mean age 20.82 years), and one included young adults (mean age 25.96 years). Quality assessment rated 2 studies as good and 2 as satisfactory. The nonrandomized trial (Choi et al, 2018, n=80) compared a smartphone group to a computer display group after 4 hours of puzzle gaming. The smartphone group had significantly higher total OSDI scores (25.03±10.61 vs 16.61±6.45, p<0.05) and higher dichlorodihydro-fluorescein intensity (141.56±22.39 vs 123.03±18.45, p<0.5), indicating greater dry eye symptoms and oxidative stress. No significant differences were found in tear break-up time, Schirmer test, or other tear film parameters. A cross-sectional study (Choi et al, 2018, n=315) found that longer self-reported daily SPU was associated with higher OSDI scores in univariable analysis (F=5.133, p=0.002), but this association was not significant in multivariable analysis. Moon et al (2014, n=288) reported that each 1-hour increase in daily SPU was associated with 1.86 times higher odds of DED (95% CI 1.07–3.24) using multivariable analysis. Moon et al (2016, n=916) found a stronger association: each 1-hour increase in daily SPU was associated with 13.07 times higher odds of DED (95% CI 5.99–28.52). Additionally, among children diagnosed with DED, those who stopped SPU for 4 weeks had a 100% reduction in DED rate compared to a 13.3% reduction in those who continued SPU (p<0.001).
**Clinical Implications:** This review provides preliminary evidence that longer daily smartphone use is associated with increased odds of DED, with effect sizes ranging from OR 1.86 to 13.07 per hour. The findings align with known associations between VDU use and DED, suggesting that SPU may exacerbate or contribute to DED through mechanisms such as reduced blink rate, incomplete blinking, and lower gaze angle. The 100% reduction in DED rate after 4 weeks of SPU cessation in one study underscores the potential reversibility of SPU-related DED. These results have important implications for public health awareness and clinical practice, supporting the development of guidelines to limit SPU duration and encourage breaks to prevent or manage DED. However, the evidence is limited by small sample sizes, cross-sectional designs (precluding causal inference), reliance on self-reported SPU and DED, and lack of generalizability beyond South Korea. High-quality prospective studies with objective measures of SPU and DED, adequate sample sizes, and control for confounders are urgently needed to confirm these findings and elucidate underlying mechanisms.