Optometry and Vision Sciences - Theses
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ItemComputer vision syndrome and blue light blocking lenses: closing the evidence gap( 2021)Computer use is ubiquitous in this digital era and the majority of computer users report eye strain, often referred to as “computer vision syndrome” (CVS) or “digital eye strain”. The most common ocular symptoms associated with CVS are visual fatigue, followed by blurred vision, and dry eyes; these symptoms can occur immediately, or after several hours of computer use. Recently, blue light has been hypothesised to be a cause of CVS and blue light-blocking lenses were introduced with an aim to alleviate symptoms of CVS. However, there is a dearth of evidence from high quality clinical trials to support the efficacy of these lenses, and the potential mechanism of action of blue light-blocking lenses for modifying CVS remains unknown. The major aim of this thesis was to close the evidence gap in relation to the use and applicability of blue light-blocking spectacle lenses for alleviating eye strain associated with CVS. First, a systematic review was conducted to investigate the efficacy and safety of different interventions for treating CVS (Chapter 2). Randomised controlled trials investigating any intervention for managing signs or symptoms of CVS were identified, appraised for risk of bias, and synthesised. A range of interventions - including optical aids, oral supplements, complementary medicines, artificial tears, environmental modifications, yoga, and rest breaks - were identified. For the risk of bias assessment, the three domains that were judged to have the highest risks of bias in the included studies were performance bias, detection bias, and industry sponsorship bias. This systematic review found, with moderate certainty, that oral omega-3 fatty acid supplementation for 45 days improved symptoms of dry eyes in computer users compared to placebo. This review also found with low certainty, that oral berry extract supplementation for 8-12 weeks improved symptoms of visual fatigue and dry eyes, compared to placebo. The studies presented in Chapter 3 and 4 investigated the knowledge and self-reported practice patterns of Australian optometrists and ophthalmologists towards prescribing blue light-blocking ophthalmic lenses. In the optometrist’s survey, three in four respondents indicated prescribing blue light blocking lenses in their clinical practice. Forty-four percent of respondents considered daily environmental exposure to blue light as a potential cause of retinal damage, and approximately one in two respondents thought blue light emitted from computer screens was an important factor in causing CVS. The two main sources of information used by the respondents to guide their practice were conference presentations and manufacturer product information. In the ophthalmologist’s survey, 88% of respondents were cataract surgeons, of whom approximately half indicated recommending blue light blocking intraocular lenses to their patients. About one in four ophthalmologists considered daily environmental exposure to blue light to cause retinal damage. Similarly, 19% of respondents considered blue light emitted from computer screens to be a cause of CVS. The two main sources of information used by ophthalmologists to guide their clinical decision-making were published research papers and conference presentations. Finally, a double-masked, randomised controlled trial (RCT) was conducted to evaluate the efficacy and safety of blue light-blocking spectacles for reducing symptoms and clinical signs of CVS (Chapter 5). A novel aspect of the study design involved a randomisation step to modulate clinical advocacy of the intervention, whereby the investigator did/did not present the assigned intervention in a positive light. We found that blue light-blocking spectacle lenses did not modulate key signs or symptoms of eye strain associated with computer use, relative to standard (clear) lenses, and the relative advocacy of the clinician had no bearing on the clinical outcome. The work presented in this thesis advances our scientific understanding, and broadens the evidence base, relating to the management of CVS, and the current clinical practice behaviours of Australian optometrist and ophthalmologists towards prescribing blue light-blocking ophthalmic products. It provides evidence that blue light-blocking spectacle lenses do not reduce computer-induced eye strain relative to clear lenses, irrespective of whether or not they are advocated for by a clinician. Overall, findings from this thesis will contribute towards informing clinical guidelines that will assist practitioners with making evidence-based clinical decisions when treating CVS.