Computers and digital devices make our lives more organized and easier, but at a cost. The cost is ocular and physiological effects. Although an enormous amount of research has already taken place regarding computer vision syndrome^1,2 and digital eye strain, with ever-changing technology, we have to admit that the long-term effects of smartphones and hand-held digital devices are not known.^3-5 This article will serve as a brief summary of both the ocular and non-ocular effects of digital eye strain and how to ameliorate the symptoms.

OCULAR AND VISUAL EFFECTS

The short-term use of smartphones and hand-held devices is associated with ocular surface, visual and aesthenopic symptoms:^3-5

• Ocular surface. Numerous studies show the use of digital devices alters blink patterns, ocular surface homeostasis and, particularly, tear film instability and oxidative markers.^6-10 Specifically, blink rate, keeping the eye open, glare, gaze-maintained, font size and flickering observed during the use of digital display units leads to symptoms of dry eye disease, particularly sore eyes, burning, stinging, itch and irritation.
  Various blink dynamics to consider include rate, amplitude and type and complete vs. incomplete. These could, indeed, negatively influence tear dynamics, regardless of the patient’s age. Simply put, the decreased blink rate leads to an increased exposure time between blinks and enables evaporation of tears. One could likely expect greater tear film instability, as seen by decrease in TBUT in individuals who have digital eye strain.
  While blink rate is reported as consistently decreased when using a computer, there are conflicting reports regarding blink rate and the use of hand-held devices. Specifically, studies show either a decrease or an increase in the number of blinks.^6-9 Although, blink rate is, indeed, task dependent and not solely based on the type of device used. Furthermore, when the task and conditions were standardized in these studies, the blink rates did not vary between digital screen and reading from printed paper.^11,12 The blink rate decreased as a function of complexity of task and constant need for attention, as required in computer games or a complex reading activity, compared to watching a movie.^11,12 All these are points to be aware of when educating your patient on the effects of digital eye strain. Further research is needed to evaluate the changes in tear film dynamics with the use of smartphones and digital devices.
• Visual. Close viewing distance or uncorrected refractive error are likely to cause accommodative and vergence-related stress, leading to symptoms of blurred vision, difficulty in focusing at different viewing distances and ache and strain in the head, particularly behind the eyes. The accommodative parameters seen to vary with digital device use are: lag of accommodation, accommodative facility and amplitude of accommodation. The lag of accommodation is greater, and there is a decrease in accommodation amplitude after using a smartphone, compared to reading printed text.^13,14
  Increased lag of accommodation is associated with increased visual symptoms, such as blur, headache and ocular soreness. Multitasking with a digital device is associated with increased need of flexibility of accommodation that is accommodative facility. Vergence changes also have been observed after use of handheld digital devices. The near point of convergence is receded greater with smartphone use than with computers, with near point convergence recovering 10 minutes after cessation of activity.^3,15 Although it is not completely clear how hand-held device use disrupts accommodation and vergence abilities, it is plausible that increased cognitive demand at different working distances, due to multitasking coupled with variation in font size and contrast, is responsible for such an adversity.
• Aesthenopia. Usually characterized by discomfort, dimness of vision and headache, aesthenopia is caused by overuse of the visual organs, dysfunction of the ocular muscles and incorrect refraction. Studies show that even in healthy adolescents, two-hour use of smartphones caused a twofold increase in ocular and visual discomfort. Even one hour of tablet or smartphone use was related to a fivefold increase in visual strain and blur.^16,17

NON-OCULAR EFFECTS

Use of computer and digital screens force positions of the body and visual gaze that can cause non-ocular side effects. These side effects:

• Head and neck pain. Computer users frequently have an upward gaze, whereas smartphone and tablet users may adopt a straight-ahead or a downward gaze. Given this, it is not surprising that a recent cross-sectional study shows adolescents who use these digital devices 14 hours or more a week experience pain in the head, neck, shoulder, hands, wrist and lower back.¹⁸
• Sleep troubles. The use of digital devices has been implicated in the disruption of the circadian rhythm, particularly in the secretion of melatonin, which controls sleep. Specifically, the intrinsic photosensitive ganglion cells, when stimulated by the blue light emitted by the digital device, can disrupt sleep if used at night or before bedtime.^19,20

AMELIORATION OF SYMPTOMS

Any management option(s) for digital eye strain should start with a comprehensive eye examination. A person who has residual refractive error, accommodative or vergence dysfunction or who is predisposed to ocular surface disease (for example, a patient using antihistamines) is likely to have exaggerated issues with the use of digital devices and will need care. Recommendations to quell the symptoms of digital eye strain:

• Educate on acuity reserve. Having VA three times greater than the demand could help decrease symptoms related to digital eye strain.^21,2 It also should be remembered that individuals often view small font on their hand-held devices, making it difficult to have three times the VA reserves.²² We suggest reviewing this information with patients and providing advice on what the appropriate font size may be to provide them with some relief.
• Discuss correct working distance. Digital hand-held devices are used at much shorter working distances than printed media, and continuous use of digital devices for an hour leads to even shorter working distances. About one in five individuals hold digital devices at <30 cm.²³ There is no set distance that will work for everyone, but a combination of an increase in font size, along with an increased viewing distance, can help.
• Educate on lighting levels. Smartphones and tablets are often used in dark environments, even in bed with completely dark surroundings. The Illuminating Engineering Society (ies.org ) recommends the luminance ratio between task and surroundings not exceed three times. We recommend demonstrating to patients what glare-free and adequate light may look like in a given situation and educating them on how the use of anti-reflection coating can provide some relief to their symptoms.
• Discuss blue-blocking lenses. Several recent studies did not find strong evidence to support the use of blue-locking lenses as a treatment for DES,^24-26 while other studies have found blue-blocking lenses may offer visual and health benefits.^27-30 Additional research is needed to assess this further. We suggest a more holistic view will have to be taken to develop better visual and ocular hygiene to help decrease DES. This holistic approaching includes taking frequent breaks, maintaining better posture and working distance and a discussion of blue blockers.
• Educate on ocular nutritional supplements. In a placebo-controlled trial, Stringham et al shows that higher doses of macular carotenoids (24 mg) led to improvement in macular pigment optical density and overall sleep quality, headache frequency, eye strain, eye fatigue and all visual performance measures in healthy adults who had >6 hour of screen time/day.³¹ Clinical trials are underway and commercial supplements of carotenoid and anthocyanins are available, which could yield an overall decrease in systemic stress and the alleviation of symptoms, due to digital eye strain.

NO PREDICTION IS FOOLPROOF

Arguably, the daily demands of life and work are likely to increase screen time for the foreseeable future. Also, electronic and digital communication is likely to increase. As research is being conducted in this area, we are likely to understand various facets and intricacies of digital eye strain, which will lead to additional related management strategies. OM

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MR. LEM earned his bachelor’s degree from the University of California San Diego in 2017. He is currently a graduate student at the Western University of Health Sciences.

DR. DAVEY is a tenured full professor at Western University of Health Sciences. He is a recent recipient of California Optometric Association’s Young O.D. of the year. Dr. Davey is the vice president of the Ocular Wellness and Nutrition Society and has relationships with ZeaVision LLC and VectorVision/Guardion Health Sciences.