The overarching theme of the thesis was to investigate the association between smart device use and computer vision syndrome. The initial study designed and developed the Open Field Tear film Analyser (OFTA) enabling a continuous, real-time assessment of the tear film and blink characteristics during smart device use. The monocular OFTA prototype was validated and showed good intra- and inter-observer repeatability relative to the Oculus Keratograph 5M and Bausch and Lomb one position keratometer. Subsequently, tear osmolarity following engagement with reading and gaming tasks on smart device and paper platforms was investigated. Discrete measures of osmolarity pre- and post-engagement with the tasks were obtained with the TearLab osmometer; osmolarity values differed between platforms when participants were engaged in a gaming task but no such difference was observed with the reading task. In addition, the influence of repeated measurements on tear osmolarity was also explored. To simulate the habitual binocular viewing conditions normally associated with smart device use, the binocular OFTA was developed. The device was used to assess the tear film and blink characteristics whilst engaging with reading and gaming tasks on smart device and paper platforms. The results revealed differences in blink characteristics and non-invasive tear break up time between the different platforms and tasks assessed. In addition, the thesis also reports on an investigation examining the real-time accommodative response to various targets displayed on smart devices using an open-field autorefractor with a Badal lens system adaptation. The results showed that accommodative latency, accommodative lag, mean velocity of accommodation, speed of disaccommodation and mean velocity of disaccommodation varied across the different platforms. Through the use of validated subjective questionnaires and smartphone apps, the relationship between duration of smartphone use and symptoms of dry eye were examined. The findings of this study demonstrated that longer duration of smartphone and personal computer use were associated with higher risk of dry eyes as indicated by subjective questionnaire outcomes.

Syfte: Syftet med studien var att utvärdera NIBUT (Non-Invasive Break-Up Time) och TBUT (Tear Break-Up Time) hos heltidsstuderande vid Linnéuniversitetet samt bidra till en ökad förståelse av ögonhälsan hos denna grupp. Metod: Tårfilmens stabilitet kontrollerades med NIBUT och TBUT, tiden mättes direkt efter en blinkning till första uppsprickningen av tårfilmens yta eller ny blinkning. NIBUT utfördes icke invasivt i Sirius och TBUT mättes i biomikroskop med fluorescein. Deltagarna fick inledningsvis svara på en enkät som gjorde det möjligt att analysera insamlad data utifrån ålder, kön, termin, skärmtid och poäng på DEQ-5 (5-Item Dry Eye Questionnaire). Svaren från DEQ-5 möjliggjorde att resultaten från NIBUT och TBUT mätningarna kunde jämföras mot upplevda symtom på torra ögon. Resultat: Studien inkluderade 36 studenter i åldersspannet 18–39 år (medianålder 23 år, IQR 5,25 år). NIBUT och TBUT visade en positiv signifikant korrelation (p <0,001). En kortare TBUT korrelerade negativt med en högre totalpoäng på DEQ-5 (p = 0,004) samt antalet terminer som studerats (p = 0,025). NIBUT visade inte några liknande samband. Referensvärdet för torra ögon diagnostisering med hjälp av NIBUT och TBUT är en tid <10 sekunder. Över hälften av deltagarna i studien, NIBUT 58% och TBUT 53%, hade en nedsatt break-up time <10 sekunder. Vilket kan vara en indikation för torra ögon problematik. Slutsats: Denna studie visar att det finns ett signifikant samband mellan NIBUT och TBUT mätningarna. Kortare TBUT har visat en signifikant korrelation med högre totalpoäng på DEQ-5, likaså har signifikanta samband mellan TBUT och fler lästa terminer konstaterats. Trots korrelationen mellan NIBUT och TBUT påverkades resultaten av skillnader mellan de två mätmetoderna. / Purpose: The purpose of the studies was to evaluate NIBUT (Non-Invasive Break-Up Time) and TBUT (Tear Break-Up Time) in full-time students at Linnaeus University and to contribute to an increased understanding of the eye health of this group. Method: The stability of the tear film was checked with NIBUT and TBUT, the time was measured directly after a blink to the first break-up of the tear film surface or a new blink. NIBUT was performed non-invasively in Sirius and TBUT was measured in a biomicroscope with fluorescein. The participants initially had to answer a questionnaire that made it possible to analyze collected data based on age, sex, number of semesters studied, screen time and score on the DEQ-5 (5-Item Dry Eye Questionnaire). The responses from the DEQ-5 allowed the results from the NIBUT and TBUT measurements to be compared against perceived symptoms of dry eye. Results: The study included 36 students in the age range 18–39 years (median age 23 years, IQR 5.25 years). NIBUT and TBUT showed a positive significant correlation (p <0.001). A shorter TBUT correlated negatively with a higher DEQ-5 total score (p = 0.004) as well as the number of semesters studied (p = 0.025). NIBUT did not show any similar correlations. The reference value for dry eye diagnosis using NIBUT and TBUT is a time <10 seconds. Over half of the participants in the study, NIBUT 58% and TBUT 53%, had a reduced break-up time <10 seconds. Which can be an indication of dry eye problems. Conclusion: This study shows that there is a significant connection between the NIBUT and TBUT measurements. Shorter TBUT has shown a significant correlation with higher total scores on the DEQ-5, likewise significant connections between TBUT and more semesters read have been established. Despite the correlation between NIBUT and TBUT, the results were influenced by differences between the two measurement methods.