Dry eye is a complex, multi-factorial disease that results in a compromised tear film and ocular surface. Clinicians and researchers alike have historically relied on an individual’s symptoms to diagnose and manage the condition, due to a lack of reliable objective methods for quantifying disease presence and severity. Of late, parameters such as tear film osmolarity and tear meniscus height have shown promise as valid methods for enumerating characteristics of the tear film that may aid the diagnosis of dry eye. Two new technologies have recently been introduced that can measure said parameters. The TearLab™ is a novel handheld nano-osmometer capable of measuring tear film osmolarity on samples as small as 50 nL. The device uses electrical conductance to measure osmolarity, and the small sample requirements purportedly allows the device to minimally disturb the natural state of the tear film. The RTVue-100 is a spectral-, or Fourier-domain optical coherence tomographer that has the ability to generate high resolution, cross-sectional images of the tear meniscus, and subsequently measure tear meniscus height. As little is published on the use of these technologies to evaluate the tear film, a series of studies was completed to determine their performance in both a normal and dry eye population.

Dry eye is a complex, multi-factorial disease that results in a compromised tear film and ocular surface. Clinicians and researchers alike have historically relied on an individual’s symptoms to diagnose and manage the condition, due to a lack of reliable objective methods for quantifying disease presence and severity. Of late, parameters such as tear film osmolarity and tear meniscus height have shown promise as valid methods for enumerating characteristics of the tear film that may aid the diagnosis of dry eye. Two new technologies have recently been introduced that can measure said parameters. The TearLab™ is a novel handheld nano-osmometer capable of measuring tear film osmolarity on samples as small as 50 nL. The device uses electrical conductance to measure osmolarity, and the small sample requirements purportedly allows the device to minimally disturb the natural state of the tear film. The RTVue-100 is a spectral-, or Fourier-domain optical coherence tomographer that has the ability to generate high resolution, cross-sectional images of the tear meniscus, and subsequently measure tear meniscus height. As little is published on the use of these technologies to evaluate the tear film, a series of studies was completed to determine their performance in both a normal and dry eye population.

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.