DIGITAL EYE STRAIN
More Screen Time = More Digital Eye Strain
Increased electronic device use has multiplied the potential stresses on the ocular system.
By Lee Hall, BSc (Hons), PhD, FBCLA, & Chantal Coles-Brennan, BSc, OD, FAAO
Digital electronic devices come in a multitude of formats, with screen shapes and sizes ranging from giant desktop monitors to tiny smartphone watches. These have multiplied the potential stresses on the ocular system, and patients report an increasing range of associated symptoms that can collectively be referred to as digital eye strain (The Vision Council, 2013).
A recent survey found that 83% of children use an electronic device for three or more hours a day (American Optometric Association, 2014; Lubell, 2014), and Americans on average now own four digital devices and spend 60 hours a week accessing content (The Nielson Company, 2014). However, this diversity of devices brings with it a wide range of working distances, font sizes, viewing angles, and luminance and contrast issues—and, consequently, a wide range of potential symptoms to be addressed in the examination room. For example, the use of smartphones results in closer working distances compared to when viewing hardcopy text, increasing the demands placed on accommodation and convergence (Bababekova et al, 2011). Consequently, there are additional considerations when evaluating symptoms resulting from the use of newer digital technologies.
Almost 70% of adults in the United States report experiencing symptoms of digital eye strain, with adults aged 18 to 34 being the most vulnerable. Despite this, almost half of adults don’t know how to, or have never attempted to, address their visual discomfort (The Nielson Company, 2014). The prevalence of digital eye strain is likely to be higher in contact lens wearers, however, because of the reduced blinking associated with the increased demands inherent in intensive near visual tasks.
A number of underlying factors are associated with digital eye strain. The causes of symptoms relating to digital eye strain can be broken down into three distinct categories: those that are vision-related (Figure 1), those that are digital screen-related (Figure 2), and those that are ocular-surface related (Figure 3).
Figure 1. Vision-related digital eye strain symptomatology.
Figure 2. Digital screen-related digital eye strain symptomatology.
Figure 3. Ocular surface-related digital eye strain symptomatology.
Digital eye strain is a condition characterized by visual disturbance and/or ocular discomfort related to the use of digital devices and results from a range of stresses on the ocular environment including: glare, defocus, accommodation, fixation disparity, dryness, fatigue, and discomfort.
While all of the usual eye examination considerations apply, questions about the number and types of devices that patients are using should be routinely asked, especially when addressing vision-related symptoms of digital eye strain. In particular, special consideration should be given to the different working distances and increased accommodative demands encountered for different devices.
Correction of astigmatism is also essential to reduce the risk of eye strain; approximately one-third of potential contact lens wearers require some form of astigmatic correction (Young et al, 2011).
Various studies have examined the role of accommodation anomalies in visual display unit (VDU)-related eye strain. Lag of accommodation does not appear to influence digital eye strain (Collier and Rosenfield, 2011); however, there is evidence that low-frequency microfluctuations in accommodation may contribute to symptoms (Gray et al, 1993). This may potentially be alleviated by the use of tints (Simmers et al, 2001).
Vergence anomalies also influence digital eye strain. A recent study reported a significant decrease in the near point of convergence (NPC) after eight hours of computer use (Watten et al, 1994), although another study found no change in either NPC, vergence, or heterophorias after five hours of sustained screen use (Nyman et al, 1985). Interestingly, subjects exhibiting more accurate vergence, i.e., tending toward zero fixation disparity, are more likely to develop symptoms over periods of prolonged screen use (Collier and Rosenfield, 2011).
A common screen-related symptom of digital eye strain is glare. Disability glare is generally self-limiting and can usually be alleviated by repositioning the screen. However, there is a higher prevalence of discomfort glare in VDU users due to the adoption of a more upright head position and reflections from overhead light fixtures and windows. Susceptibility to glare has also been shown to increase with increasing age (Cole et al, 1996).
Several studies have examined the association between muscle activity and symptoms of discomfort. One study in particular found significant correlation between blood flow in the orbicularis oculi muscle and symptoms (Thorud et al, 2012). The results suggest that pain around the eye may originate from over-action of the orbicularis muscle (squinting).
Ergonomics is also an important consideration with digital devices; how to minimize discomfort will vary depending on the type of device in use. With hand-held devices (e.g., smartphones or gaming devices), the closer-than-normal working distance is the main source of discomfort. For laptop and desktop computing, factors such as viewing angle and chair height should be addressed to minimize symptoms associated with musculoskeletal problems (Rosenfield, 2011; Hayes et al, 2007).
A number of studies have reported decreased blink rate (Portello et al, 2013; Patel et al, 1991; Collins et al, 2006) and incomplete lid closure (Chu et al, 2014) among screen users, which can result in uneven tear distribution and can foster a thin, unstable tear film. Dryness and associated symptoms are also commonly encountered by screen users who have otherwise healthy eyes. These effects may be further exacerbated for contact lens wearers; a recent online survey of VDU users revealed that, on average, 85% of wearers experienced at least one dryness-related symptom compared to 71% of non-wearers (González-Méijome et al, 2007).Typical clinical manifestations may include increased corneal “smile”-type desiccation staining and conjunctival staining.
A recent study (Pult et al, 2008) has shown that lens wearers who have dryness symptoms exhibit significantly greater lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOFs), which may ultimately reduce tolerance to lens wear without careful management.
The application of multiple digital devices in the home and work environments presents a wide range of challenges for users and, consequently, for eyecare professionals. In particular, it is important to correct for a range of working distances and font sizes. The choice of vision correction may have an impact on at least some of the digital eye strain-related symptoms experienced by patients.
For contact lens wearers, this may encompass the use of either over-spectacles or multifocal, monovision, or modified monovision modes of correction to achieve optimal visual results and possibly help reduce certain digital eye strain symptoms.
The heightened prevalence of dryness with VDU use for lens wearers might also be an indication for a change in lens material, modality, and/or lens care solution to optimize surface wettability and thus enhance comfort. Additional clinical evaluation of specific vision correction options will help to better determine whether and how these options can reduce certain digital eye strain symptoms. For instance, the use of lens rewetting drops may also reduce wearer symptoms. Additionally, ergonomics should be considered to provide the most comfortable physical working conditions.
As the use of digital devices continues to grow, symptoms of digital eye strain will demand increasing attention from eyecare practitioners, particularly so with contact lens patients for whom additional factors can tip the scales for a variety of symptoms. CLS
For references, please visit www.clspectrum.com/references and click on document #235.
This article was sponsored by Johnson & Johnson Vision Care, Inc. (JJVCI), which also provided editorial assistance.
Dr. Hall works for Visioncare Research, an independent research organization to the eyecare industries. He is also a Visiting Research Fellow at Aston University, Birmingham, in the United Kingdom. He has received research funding from Johnson & Johnson, Alcon, and CooperVision.
Dr. Coles-Brennan is manager, Global Strategic Medical Affairs for Johnson & Johnson Vision Care, Inc.