Those of you old enough to remember the Jackson Browne song “Doctor, My Eyes” may now have the tune stuck in your head; however, it brings to mind a serious question: How many times have you, as a practitioner, heard from your patients that their eyes are tired? It is troubling that you may not hear patients make mention of it as often as you should. Even worse, why are patients saying it and what can you do about it?
We all work hard each and every day; so do our eyes. Likewise, as the rest of the body experiences fatigue throughout the day, our eyes follow suit. This all makes sense, but why does this happen? The answer may not be as simple as you might think.
Tired eyes, referred to in the medical literature as asthenopia, may also be known by a variety of terms such as eyestrain, computer vision syndrome or the now-preferred digital eyestrain. Nonetheless, the terms themselves, and the variety used to describe the condition, hint at an underlying etiology and a lack of its true understanding.
Digital eyestrain is a diagnosis of exclusion. Patients may complain of one or a combination of multiple symptoms, such as tired eyes, shoulder pain, headache, fatigue, eye irritation and pain, blurred or double vision, light sensitivity, tearing, dry eyes and trouble focusing. These complaints may differ between patients and can vary for an individual over time.
Asthenopia has been well reported in the literature; however, we have only recently seen its resurgence, potentially in association with the increase of digital device use.1-5 In particular, according to a recent Vision Council survey, upwards of 90% of Americans use digital devices at least two hours per day, with 60% using them five or more hours per day and 70% using two or more devices at a time—a staggering figure with respect to the potential implications for eyestrain.6 In fact, 73% of all American adults own a computer and 68% own a smartphone.7
Devices are rapidly replacing other forms of communication media; 63% of Americans use a smartphone, computer, tablet or e-reader as opposed to traditional printed paper.8 This is only one task capable of being completed on the devices, and they are performing it for an average of 60 hours per week.9
To add to this, 84% of smartphone and tablet owners say they also use their devices as second screens while watching television.9 Chalk that up to the rise of social media and a desire to share the experience with friends and family as it happens.
|Fig. 1. Frequency with which eye fatigue is experienced by 609 respondents to an online survey. Subjects were told, “Eye fatigue is the physical discomfort of your eyes after spending periods of time throughout the day in front of a digital screen, like a computer or smartphone.” Based on that definition, subjects were asked how often they experienced eye fatigue, with options ranging from ‘multiple times per day’ to ‘I never experience eye fatigue.’ Click image to enlarge.|
Sounding a cautionary note about our digital device habits, the Vision Council survey reported that 65% of Americans experience symptoms of eyestrain while using these devices, with even more frequent reports occurring in adults younger than 30 years of age. 6 Comparable numbers have been reported by other studies.4,8 Millennials and the generations who will follow them live in a world where the use of digital screens for many aspects of communication and education is their default experience.
Similarly, we at Indiana University School of Optometry recently surveyed a random sample of 18- to 39-year-old adults who do not currently wear multifocal correction or gas permeable contact lenses. We questioned the 609 respondents on how often they experienced eye fatigue, which was defined as physical discomfort of their eyes after spending periods of time throughout the day in front of a digital screen. More than one-quarter of respondents stated they experienced eye fatigue at least one time per day and more than half reported experiencing it more than once per week (Figure 1).
Causes and Consequences
While it is possible that we are all just working our eyes harder than ever before, the possibility exists that digital devices are increasing the incidence of eye strain. The visual demands and effects of digital devices on the ocular system are inherently different from traditional print in many ways.
• Screen size. Mobile device screen sizes are smaller than typical newspaper formats. Although text sizes are theoretically easily increased on digital devices, people most often choose to view text at considerably smaller point size than newspaper print and at the smaller end of the ISO recommendations.10-12 Small text and screens, and the associated closer viewing distance seen with digital device use may require a sustained, increased accommodative and convergence demand, stressing the muscles of these systems.
• Posture. When viewing smaller character sizes on digital devices, posture may also be frequently altered to compensate for the limits of visual acuity. These postural adjustments include flexing the thoracic and lumbar spine and lowering torso height, resulting in incorrect posture. When viewing small characters at a far viewing distance, the head is also frequently moved forward, resulting in increased muscle load on the upper vertebrae, which is balanced by an increased load on the muscles in the neck, shoulders and upper back.13 Reflective glare from screens is also a frequent complaint of users of digital devices, which is not seen when using traditional print. These reflections may also result in altered head and neck postures when working on digital devices.11
• Blink rate. Any task with a high cognitive demand results in a decreased blink rate, regardless of the medium.14 Digital device use has been shown to decrease the blink fullness—an increase in incomplete blinks—over completing the same task on hardcopy.15 Increased corneal exposure may occur, which can result in increased evaporation of the tear film, leading to more symptoms.
• Blue light. Many of these digital devices have been shown to emit high levels of short-wavelength blue light, which research shows has a negative impact on melatonin production. Repeated, prolonged exposure to blue light can result in altered circadian rhythms and the possibility of increased general fatigue which, in turn, impacts the frequency and amount of eye fatigue.16,17
Although it is clear that many ways exist for digital devices to impact our visual system, and the demands on our eyes are different than they were only a few decades ago (when Jackson Browne was well known), it may not be an exaggeration to question whether or not we truly understand what it means when someone says they have tired eyes. Importantly, the underlying etiology of eyestrain must be better understood.
Sorting Out the Symptoms
In an effort to better understand what patients mean when they say they have eye fatigue, our survey asked respondents to report the frequency and severity of symptoms they experience during instances of eye fatigue. In general, the frequency and severity of these symptoms fall into three main groups or factors (Figure 2). Symptoms of eyestrain, soreness, tired eyes and headache all fall together in one grouping called primary global sensations. A second group is comprised of blurred vision and “floating” text, which we refer to as visual sensations. The final group—irritation, dryness, burning and tearing—we refer to as secondary surface sensations.
The results of our survey indicate that regardless of frequency or severity, a respondent reports concerning an individual symptom, each eyestrain symptom can be reliably differentiated from one another, even as they occur simultaneously. We believe this categorization scheme helps uncover the underlying etiology and direct our efforts toward appropriate treatment options.
What Can We Do?
Although better categorization of symptoms can provide greater clarity of mind, questions remain about the underlying etiologies. Do issues of accommodation, convergence, environment, surface dryness, blue light or a combination of these factors cause eye fatigue? Ultimately, treatments need to match causes and be tailored to the individual’s usage habits and symptoms. For now, we can take advantage of symptom categorizations to direct our management. For example, the primary global sensations that individuals describe may be aided by more holistic lifestyle changes or overall aids, such as attention to ergonomic factors, taking frequent breaks or reducing blue light exposure.
Establishing an ergonomic working environment should be emphasized to our patients. Ideally, the head and neck will upright, face will be directed at the screen, reflections will be minimal and the patient will either be standing up or using an ergonomically supportive chair. Strategies to reduce blue light include spectacle lenses with blue-blocking filters or coatings available from many manufacturers, and software on digital devices that limits blue light emission, like Apple’s Night Shift feature for iOS devices. These can also positively impact the patient’s duration and quality of sleep, helping to mitigate the elements of eyestrain that derive from a state of general fatigue.
The secondary surface sensations that individuals describe may be addressed by encouraging them to take more breaks, blink more often and use lubricating eye drops. Additionally, specific soft contact lens materials or surface coatings may minimize surface sensations related to tear evaporation that stems from reduced blink rates during device use.
Clinicians can address the visual sensations individuals describe with a variety of optical manipulations to their corrective lenses such using as low-add progressive addition lenses, or aspheric or zonal contact lenses, all with some variation of lens power to supplement the eyes’ natural accommodative system.
|Fig. 2. A diagram demonstrating the results of a confirmatory factor analysis, where both symptom frequency and severity as described by subjects with eye strain fall into three distinct groups, where the relative symptom importance within each group is described by the text size. Click image to enlarge.|
Given the surprising complexity at work in how our eyes interact with digital screens, we should keep all options in mind, and in the conversation. A mix of common sense advice and targeted optical remedies can ensure uneventful long-term device use for patients.
It is clear that a potentially large percentage of our patients struggle with symptoms of eye fatigue of high frequency and severity. Many, although struggling, are not voicing their concerns during visits. This highlights the need for practitioners to proactively ask our patients if they are experiencing symptoms and, if so, work with them toward minimizing them insofar as that is possible in this digital age. And we too should practice what we preach, being mindful of our own device use. After all, without digital devices, how could younger readers Google to find out who Jackson Browne was, or maybe even read this article?
The rewards of having access to the world’s resources at the touch of a button outweigh the symptoms that accompany digital device use, but with a change in the times comes the need for practitioners to keep pace with changing patient needs in this brave new world of bytes and blue light.
Dr. Kollbaum is Associate Dean for Research, and Director of the Borish Center for Ophthalmic Research at the Indiana University School of Optometry. His areas of research interest encompass contact lens optics, contact lens fitting and design, presbyopia, keratoconus, refractive surgery optics, corneal topography, and predictive modeling. Dr. Kollbaum worked in a private multidisciplinary practice prior to returning to IU where he now teaches and performs research in the areas of contact lenses and optics.
Dr. Meyer received her doctorate in optometry in 2012 from Indiana University where she completed a primary care residency. In 2013, she joined Dr. Kollbaum and the rest of the Clinical Optical Research Lab. Dr. Meyer holds membership to the AOA, the Indiana Optometric Association and her local Stonebelt Optometric Society. Her areas of research interests include contact lens fitting and design, patient education and compliance, presbyopia and keraoconus.
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