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Purpose: In 2007, the smartphones as we know them today entered the market. The introduction of this digital unit has had a significant impact on our mass media habits and has caused an increase in time spent conducting near work. As near work increases the accommodative response, causing NITM, it is known that excessive viewing time at near can affect the refractive measurements at far. The aim of this study is to investigate the incidence of pseudomyopia and NITM in young healthy myopic Norwegian adults by different noncycloplegic and cycloplegic measurements, and its possible association to recent years change in mass media habits. Method: In order to achieve data of habitual and fully relaxed refractive status, measurements of noncycloplegic autorefraction, subjective refraction, retinoscopy and cycloplegic autorefraction were performed and compared on 44 healthy young myopic adults who owe a smartphone. A questionnaire primarily about the participants' use of digital units was also filled out. The age range was 18 to 40 years (mean 29.6 ± 4.7 years). Results: When comparing the mean spherical equivalent (SE) of the noncycloplegic autorefraction with (1) the cycloplegic autorefraction and (2) the subjective refraction, the noncycloplegic autorefractor yields more negative values: (1) -0.433 ± 0.372 D; p=0.000; (2) -0.206 ± 0.309 D; p=0.000 respectively. The mean SE of subjective refraction also yields more negative value than the cycloplegic autorefraction: -0.228 ± 0.406 D; p=0.000. Comparison of the mean SE of cycloplegic autorefraction and the retinoscopy presents no significant difference in value: -0.021 ± 0.323 D; p=0.678. 40% of the participants have a noncycloplegic autorefraction value which is more negative equal to 0.50D or more compared to the cycloplegic autorefraction. Within the same measurement comparison, 24.4% have a negative value of more than 0.50D. Participants with a low accommodative lag of 0.50D or less (5) measured with the cross-cylinder test, had a significantly higher mean difference in SE between noncycloplegic and cycloplegic autorefractions than participants with a higher accommodative lag (6): (5) -0.642 ± 0.375 D; (6) -0.317 ± 0.322; p=0.05. Conclusion: The present results confirm that noncycloplegic autorefraction yields more negative values than subjective refraction, cycloplegic autorefraction and retinoscopy. There are significant differences between the refractive values of all methods (p < 0.05) except the cycloplegic autorefraction and the noncycloplegic retinoscopy. There was an incidence of 7% pseudomyopia among the participant when comparing the cycloplegic autorefraction with the noncycloplegic subjective refraction (difference > 0.50 D), where 4.5 % would not have been detected without cycloplegic refraction. No significant association between the use of digital units or smartphones and pseudomyopia and NITM was found in this sample of young myopic adults. A larger sample is recommended to confirm these results.

Volumetric display shows promising implications for healthcare related applications as an innovative technology that creates real three-dimensional (3D) image by illuminating points in three-dimensional space to generate volumetric images without image separation. We used eccentric photorefractometry to objectively study ocular performance in a practical environment by evaluating near work-induced refraction shift, accommodative microfluctuations, and pupil size for 38 young adults after viewing anaglyph, and volumetric 3D content for prolonged time. The results of our study demonstrate that participants who performed relative depth estimation task on volumetric 3D content were less likely to experience task-induced myopic refraction shift. For both 3D content types, we observed pupil constriction, that is possibly related to visual fatigue. For anaglyph 3D pupil constriction, onset was observed significantly sooner, compared to volumetric 3D. Overall, sustained work with 3D content, and small disparities or the fully eliminated possibility of accommodation-vergence conflict, not only minimizes near work-induced myopic shift, but also provide beneficial accommodation relaxation that was demonstrated in this study as hypermetropic shift for nearly half of participants.

Maģistra darbs ir uzrakstīts latviešu valodā uz 37 lapām. Tas satur 17 attēlus, 3 tabulas, 1 pielikumu un 34 atsauces uz literatūras avotiem. Darba mērķis: izpētīt akomodācijas atpalikšanas saistību ar pastiprinātu tuvuma darbu un sūdzībām par redzi tuvumā. Dalībnieki: 12 dalībnieki, kuriem nav tuvredzības, izteiktas heteroforijas vai heterotropijas, acu kustību traucējumu, ir laba binokulārā redze un stereoredze. Rezultāti un secinājumi: Rezultāti parāda, ka akomodācijas atpalikšana redzes slodzes ietekmē ir atkarīga no katra dalībnieka individuālajām redzes funkciju īpatnībām (piemēram, refrakcijas lieluma) un vispārējā noguruma. Pat nelielas nekoriģētas hipermetropijas gadījumā novēro lielas akomodācijas atpalikšanas svārstības gan 25 cm, gan 40 cm attālumā. Eksperimenta rezultāti apstiprina, ka ne vienmēr subjektīvās sūdzības, kas norādītas aptaujas anketās, ir saistāmas ar akomodācijas darbības traucējumiem., Master thesis is written in Latvian, on 37 pages. It contains 17 figures, 3 tables, 1 appendix and 34 references. Aim: to study the effect of intensive near work at very close distances on the lag of accommodation and its possible relation to asthenopia. Participants: 12 participants without myopia, no marked heterophoria, heterotropia, or eye movement problems, have single binocular vision and good stereovision. Results and conclusions: Our results shows that the intensive near work at very close distances affect lag of accommodation depending on the inter-individual differences (like refraction) and general fatigue of participants. Even small uncorrected hyperopia can produce large fluctuations of lag of accommodation both at 25 cm and 40 cm distances. The results of experiment confirm that subjective complaints not always could be associated with accommodation disorders.