Blink Rate Measured In Situ Decreases While Reading From Printed Text or Digital Devices, Regardless of Task Duration, Difficulty, or Viewing Distance.

Purpose: To compare blinking measured in situ during various tasks and examine relationships with ocular surface symptoms. The day-to-day repeatability of the blink rate and interblink interval was assessed. Methods: Twenty-four students (28.6 ± 6.3 years; 8 male and 16 female) completed six reading tasks (printed text, laptop, TV, smartphone, smartphone at 50% brightness, smartphone with complex text), and two nonreading tasks (conversation, walking) in a randomized cross-over study. Ocular surface symptoms and clinical signs were assessed. The blink rate and interblink interval were measured using a wearable eye tracking headset. Blink parameters were compared across tasks and time (linear mixed model and post hoc comparisons with Bonferroni correction). Associations between blinking, symptoms, ocular surface, and clinical signs were assessed (Spearman's correlation). The smartphone reading task was completed twice to determine the coefficient of repeatability. Results: The blink rate was lower (mean 10.7 ± 9.7 blinks/min) and the interblink interval longer (mean 9.6 ± 8.7 seconds) during all reading tasks compared with conversation (mean 32.4 ± 12.4 blinks/min; 1.5 ± 0.6 seconds) and walking (mean 31.3 ± 15.5 blinks/min; 1.9 ± 1.3s) (P < 0.001). There were no significant differences in blink parameters between any of the reading tasks or between conversation and walking. Changes in blinking occurred within 1 minute of starting the task. No associations were evident between blink rate or interblink interval and ocular surface symptoms or signs. The coefficient of repeatability was ±12.4 blinks/min for blink rate and ±18.8 seconds for interblink interval. Conclusions: Spontaneous blinking can be measured reliably in situ. The blink rate was decreased and the interblink interval increased during reading compared with conversation and walking. Changes in blinking were immediate, sustained, and not associated with ocular surface symptoms or signs.

Smartphone gaming induces dry eye symptoms and reduces blinking in school-aged children.

PURPOSE: Smartphone use by children is rising rapidly, but its ocular surface impact is unknown. This study examined the effect of smartphone use on blinking, symptoms, and tear function in children. METHODS: Prospective intervention study where 36 children aged 6-15years (14 M:22 F) played games on a smartphone continuously for one hour. Symptoms (SANDE, IOSS, NRS) and tear film (lipid layer thickness, tear secretion, stability) were assessed before and after gaming. Blink rate and interblink interval were measured in situ using an eye tracking headset, before (during conversation) and continuously throughout gaming. Symptoms and tear film changes were examined using paired t-tests. Changes in blinking throughout one hour were examined using repeated measures ANOVA, post-hoc comparisons with Bonferroni correction. Associations examined using Pearson bivariate correlation. Significance level was 0.05. RESULTS: Symptoms worsened following one hour smartphone gaming (SANDE + 8.2units, p = 0.01; IOSS + 1.3units, p < 0.001; NRS-average +6.3units, p = 0.03; NRS-comfort +7.6units, p = 0.04; NRS-tiredness +10.1units, p = 0.01), but tear film remained unchanged. Blink rate reduced from 20.8 blinks/min to 8.9 blinks/min (p < 0.001) and interblink interval increased from 2.9 s to 8.7 s (p = 0.002) within the first minute of gaming relative to baseline conversation, and this effect remained unchanged throughout one hour of gaming. CONCLUSIONS: Smartphone use in children results in dry eye symptoms and immediate and sustained slowing of blinking, with no change in tear function evident up to one hour. Given the ubiquitous use of smartphones by children, future work should examine whether effects reported herein persist or get worse over a longer term causing cumulative damage to the ocular surface.

Blinking and normal ocular surface in school-aged children and the effects of age and screen time.

PURPOSE: Baseline ocular surface characteristics in children require investigation. This study characterised blinking and relationships with ocular symptoms, tear film and digital device use. METHODS: 45 children aged 6-15 years (56% female) participated in a cross-sectional study. Ocular surface symptoms (Instant Ocular Symptoms Survey, Dry Eye Questionnaire 5, Symptoms Assessment in Dry Eye, Ocular Surface Disease Index, Ocular Comfort Index and Numerical Rating Scale) and clinical indices (lipid layer thickness, tear secretion and stability, meibomian gland) were assessed. Blink rate and interblink interval were measured in situ using a wearable eye-tracking headset (Pupil Labs GmbH, Germany). Associations between blinking, ocular surface, age, and digital device use (bivariate and partial correlations) and between automated and manually counted blink rate (Bland & Altman) were examined. RESULTS: Mean blink rate and interblink interval were 20.5±10.5 blinks/min and 2.9±1.9 s during conversation. There was no difference between automated and manual blink rate (p=0.78) and no relationship between blinking and digital device use, age or sex. Mean group symptoms were within normal range and not associated with clinical measurements including blinking. Greater tear volume was associated with a faster blink rate (r=0.46, p=0.001) and shorter interblink interval (r=-0.36, p=0.02). Older age was associated with improved tear volume (r=0.37, p=0.01) and stability (r=0.38, p=0.01). CONCLUSIONS: Blinking characterised in situ was not impacted by age or habitual digital device use. A faster blink rate was associated with greater tear volume but not symptoms. Improved tear function was found with age suggesting that the ocular surface continues to develop through childhood.

Dry eye symptoms in children: can we reliably measure them?

PURPOSE: Many dry eye questionnaires are available, but these may not be suitable for paediatric eye care. The feasibility of use and repeatability of symptom questionnaires administered to children was examined. METHODS: Participants aged 6-15 years (n = 62; 25M:37F; 40% male) completed six questionnaires twice in random order at a single visit: Symptoms assessment in dry eye (SANDE), ocular surface disease index (OSDI), numerical rating scale (NRS), ocular comfort index (OCI, n = 30), dry eye questionnaire 5 (DEQ-5) and the instant ocular symptoms survey (IOSS). Completion time and need for assistance were recorded and relationships with age examined (Pearson correlation, independent t-test). The number of participants requiring assistance and with which items were compared (linear mixed model, pairwise test). Repeatability (coefficient of repeatability (CoR), limit of agreement, bias) and intraclass correlation coefficient (ICC) were examined. RESULTS: Completion time was ≤2 min for each individual questionnaire. Younger participants took longer to complete (r = -0.43 to -0.60, p ≤ 0.01), and required more assistance (p ≤ 0.001). Forty-eight participants required assistance with at least one questionnaire. Older children (13-15 years) only required assistance with OSDI (p ≤ 0.004) and NRS (p ≤ 0.003). Participants required more assistance with SANDE, OSDI and NRS than with DEQ-5 and IOSS (p ≤ 0.02) and with gritty (OSDI, 77% of participants; OCI, 100%) and foreign body sensation (NRS, 92%) items. CoR was similar for all questionnaires with no evidence of a learning effect (p > 0.05). ICC was moderate to excellent. CONCLUSIONS: Dry eye questionnaires can be used reliably in paediatric eye care; more time and assistance may be required for younger children. The DEQ-5 and IOSS are recommended for use in younger age children.

The ocular surface in children: A review of current knowledge and meta-analysis of tear film stability and tear secretion in children.

PURPOSE: A review of ocular surface and meta-analysis of tear stability (tear break up time, TBUT) and tear secretion (Schirmer test) values in healthy children was conducted. METHODS: Articles published between 1996 and 2017 indexed on MEDLINE, PubMed, Embase, Scopus and Google Scholar were retrieved using defined search terms. Statistical analysis (including sensitivity analysis and meta-regression) was performed. RESULTS: 23 studies were summarised (5,291 participants; neonates (0-29 days), infants (1 month - 1 year) or children (1-18 years) and a meta-analysis conducted using 15 eligible studies (1,077 participants). The combined mean TBUT in children was 14.64 seconds (s) (95% CI, 11.64, 17.64) and 21.76 s (95% CI, 20.43, 23.09) for sodium fluorescein TBUT and non-invasive TBUT respectively (NIBUT). The combined mean NIBUT was 32.5 s (95% CI, 31.78-33.22) in neonates. The combined mean Schirmer I with and without anesthesia were 16.26 mm/5 min (95% CI, 13.17, 19.36) and 29.30 mm/5 min (95% CI, 27.65, 30.96) in children and 9.36 mm/5 min (95% CI, 6.54, 12.18) and 17.63 mm/5 min (95% CI, 12.03, 23.23) in neonates. Meta-regression showed a significantly lower TBUT in children from studies conducted in Asia (p = 0.004). CONCLUSION: There is paucity of data on ocular surface variables in healthy children, making it difficult to draw valid comparisons with adult values.