Successful contact lens wear is dependent upon a healthy ocular surface environment. Any alteration or disruption of this complex biological system can contribute to dry eye disease and can increase the risk of contact lens discomfort and discontinuation. Although contact lens wear itself can initiate tear film instability, a host of other environmental factors can also disrupt the tear film and contribute to contact lens discomfort and intolerance.

The most common environmental factor is the continuous use of digital devices for prolonged periods by nearly every segment of the population. The Vision Council estimated that 80% of American adults use digital devices for more than two hours per day, with nearly 67% using two or more devices simultaneously, and 59% report experiencing symptoms of digital eye strain (DES).¹

DES, formerly known as computer vision syndrome, consists of a general group of eye- and vision-related problems resulting from prolonged use of digital devices.² Symptoms include eye strain, dry eyes, headaches, and blurred vision as well as neck and shoulder pain. A topic related to digital device use that has received increasing attention is the effect of high-energy visible (HEV) or blue light on vision and ocular health.

This article will explore the interaction between contact lens discomfort and digital eye strain. It will also review the effects of blue light on the visual system and ocular surface.

THE UNSOLVED MYSTERY OF CONTACT LENS DISCOMFORT

Contact lens discomfort (CLD) refers to dryness, irritation, discomfort, and ocular fatigue that increases throughout the day while lenses are worn. The 2013 Tear Film & Ocular Surface Society (TFOS) International Workshop on Contact Lens Discomfort developed the following definition:³

“Contact lens discomfort is a condition characterized by episodic or persistent adverse ocular sensations related to lens wear, either with or without visual disturbance, resulting from reduced compatibility between the contact lens and the ocular environment, which can lead to decreased wearing time and discontinuation of contact lens wear.”

The impact of CLD, as stated by the TFOS Workshop, is that this condition is primarily responsible for between 12% and 51% of contact lens wearers discontinuing or dropping out of contact lens wear.³ This is a significant condition that directly affects patient satisfaction and quality of life and indirectly affects practice growth and revenue.

The application of a contact lens divides the tear film into two sections: a pre-lens tear film and a post-lens tear film. This cleaving of the tear film disrupts normal structure and function in multiple ways. The pre-lens tear film, for example, has reduced lipid layer thickness, reduced tear volume, and increased evaporation rate compared to the normal tear film. So, simply placing a contact lens on the eye is itself detrimental to normal tear film physiology and may contribute to discomfort and other symptoms.

The TFOS Workshop organized the myriad of possible contributors to CLD into two broad categories: contact lens-related factors and environmental factors (Figure 1). The contact lens factors are relatively straightforward, but the environmental factors are more complex and variable. Two of the four environmental factors—the ocular environment and the external environment—are also negatively impacted by digital device use. Staring at a digital screen for prolonged periods will decrease blink frequency, decrease blink quality (incomplete blinks), and increase instability and evaporation of the tear film. The low humidity, ventilation, and air quality of the typical office environment will likewise contribute to tear film disruption and CLD. The use of digital devices can therefore exacerbate and amplify the negative effects of a contact lens on the tear film and ocular surface.

Although the symptoms of CLD overlap to some extent with the symptoms of digital eye strain, it is important to note that with CLD, the symptoms are present only during contact lens wear and resolve when contact lenses are removed. Even after contact lens removal, symptoms of DES may still be present, but with lesser severity compared to wearing contact lenses. Despite advances in contact lens polymers, coatings, solutions, wearing modalities, and manufacturing techniques, CLD is still an unsolved mystery that affects a large proportion of contact lens wearers.³

A CLOSER LOOK AT DIGITAL EYE STRAIN

DES is a group of ocular and visual symptoms associated with using digital devices, and symptoms generally increase with the duration of screen viewing. As many as 90% of digital device users experience one or more symptoms, such as asthenopia, dry eyes, blurred or fluctuating vision, and neck or back pain. Table 1 lists the multitude of ocular, visual, and musculoskeletal symptoms reported with DES.

Symptoms generally occur when individuals’ visual abilities cannot comfortably meet the demands of the computer task.^4,5 The extent and severity of symptoms are related to patients’ visual abilities and the duration of time viewing the digital screen.² The multiple symptoms can be broadly grouped into vision-related and ocular surface-related.^4,5 The former includes blurred vision, eye strain, headache, focusing problems, diplopia, and sore, tired eyes, while the latter includes burning, irritation, ocular dryness, and tearing (Figure 2). Another symptom classification system is based on device-specific causes (Figure 3).

Although symptoms can overlap between the two groups, the nature and severity of symptoms can help guide diagnostic testing and management. Another clinical point is that a contact lens wearer can be affected by both CLD and DES. Following contact lens removal, the same or similar symptoms may still be present, but with less severity, due to continual viewing of digital screens as well as to underlying dry eye disease.

Several recent review articles have described and summarized the multiple physiological and environmental factors contributing to DES. These include uncorrected refractive error (including presbyopia), altered blink pattern (decreased frequency and incomplete lid closure), accommodative and vergence disorders, dry eye/ocular surface disease, glare on digital screens and excessive exposure to bright light (including blue light), close working distances, smaller font sizes, and workstation design.^4-7

In addition to a medical and visual history, practitioners should also perform an assessment of the number and type of digital devices used, screen positions, working distances, and workstation design. Evaluation of current spectacle designs and powers, as well as contact lens wear and care, is essential. Careful refraction, with special attention to correcting low hyperopia, astigmatism, and/or presbyopia, is obviously a critical component. Accommodative and binocular vision testing are also important, when indicated, due to the more intense oculomotor near demands of digital screens compared to printed hard copy.

Because DES is multifactorial in etiology, the management is also multifaceted and should be tailored to each patient. The prescription of occupational- or task-specific spectacles with a broad intermediate vision zone at eye level is a common and effective treatment. A variety of occupational spectacle lens designs, including computer-specific progressive addition lenses, can provide high-quality intermediate and near vision. General purpose progressive addition lenses may not be satisfactory due to the position and narrow width of the intermediate and near vision zones.^4,7 Table 2 lists other general management options.

THE BLUE LIGHT CONTROVERSY

The impact of HEV (380nm to 500nm) blue light exposure on general health and potential effects on vision and ocular health has been a popular topic in the lay press and at professional meetings. Our ubiquitous digital device screens use light-emitting-diode (LED) technology that emits greater amounts of short-wavelength blue light compared to earlier technology. Although the HEV light produced by cell phones is several hundred times less intense than that found in outdoor sunlight, there is concern that these low-energy screens are often held in close proximity to the eyes continuously for hours at a time, increasing the overall exposure dose. In addition to digital devices, indoor lighting systems, such as compact fluorescent lights (CFLs) and other sources, emit peaks in the blue light region. So all of us are exposed to high-energy visible blue light, both indoors and outdoors, every day for much of our lives. HEV light is transmitted through the ocular media and absorbed by the retinal photoreceptors and retinal pigment epithelium, in contrast to ultraviolet radiation that is nearly completely absorbed by the cornea and crystalline lens.⁹

As with ultraviolet radiation, there are positive and negative effects of blue light. The primary positive effect of natural daylight is modulating the biological circadian clocks necessary for the normal sleep-wake cycle. Blue light comprises approximately 25% to 30% of outdoor sunlight, which stimulates cortisol production and suppresses melatonin secretion during daylight hours. This results in alertness, mood elevation, concentration, and general wakefulness. Dim illumination and darkness at night stimulates melatonin secretion from the pineal gland, allowing drowsiness and deep sleep. The melatonin cycle is mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs). These ipRGCs contain a chromophore (melanopsin) that has peak absorption in the 470nm to 480nm range. Excessive blue light exposure prior to bedtime suppresses melatonin secretion and may disrupt the normal sleep cycle.⁹

Another potential benefit of natural sunlight exposure in children is the prevention or delayed onset of myopia development. A growing body of evidence from animal and human studies indicates that daily exposure to outdoor sunlight is significantly associated with lower rates of incident childhood myopia. Given the worldwide epidemic of myopia and the increased ocular morbidity associated with high myopia, lifestyle modifications to promote outdoor daylight exposure in children may prove to be an effective, low-cost intervention. Further research is needed to elucidate this association, and short-wavelength blue light may play an important role.^10,11

A major unanswered question is whether viewing low-intensity digital screens at close distances for hours each day over a long duration (years or decades) increases the risk of retinal damage with vision loss. Although in vitro laboratory studies show that blue light can damage photoreceptor cells and retinal pigment epithelial cells via a photochemical mechanism, there is no epidemiological evidence showing damage to human eyes from prolonged viewing of digital devices.⁶ The various light-protective mechanisms in the human eye include pupil constriction, squinting, yellow chromophores in the adult crystalline lens, macular xanthophyll pigment, retinal antioxidants, and enzymatic repair mechanisms. Epidemiological studies exploring the association of sunlight (and blue light) exposure and age-related macular degeneration development show mixed results.¹²

Because blue light exposure in sunlight is several hundred times more intense compared to digital device screens, it is logical to recommend sunglasses that filter blue light and ultraviolet radiation. Many industry-sponsored articles recommend spectacle lenses that attenuate the shorter HEV wavelengths (415nm to 455nm) associated with photochemical retinal damage but allow transmission of the longer HEV wavelengths that modulate the sleep-wake cycle. Many such spectacle lens products are currently available. These blue-light-filtering glasses are reported to filter approximately 10.6% to 23.6% of the targeted wavelengths, so their protective effectiveness is unknown at the present time.¹³

Some practitioners and industry groups advocate that nearly all digital device users should use HEV-filtering glasses to minimize chromatic aberration and glare and to perhaps decrease the cumulative risk of photochemical retinal damage and AMD development.¹⁴ In contrast, several consumer-focused articles in the public section of the American Academy of Ophthalmology web site do not recommend using blue light-blocking glasses because there is no evidence of retinal damage from digital devices.¹⁵ A reasonable approach may be to recommend blue-filtering glasses for patients who have signs of, or who are at high risk for, early retinal disease, as normal retinal repair mechanisms may be compromised. As with many unanswered clinical questions, practitioners should stay abreast of the scientific literature and use their best judgement in prescribing any treatment for given patients.

HELPING CONTACT LENS WEARERS IN THE DIGITAL WORLD

Most patients who wear soft contact lenses and use digital devices extensively for work or school, shopping, relaxing, and socializing will experience temporary or persistent symptoms to varying degrees. The combination of soft contact lens wear and extensive digital device use, along with other risk factors, increases the likelihood of discomfort and/or asthenopia. A patient’s visual tasks, ocular physiology, binocular function, systemic status, and environment all play significant roles. Patient management is likewise multifaceted and should be individualized as much as possible. Table 2 lists various management options.

Nonspecific first-line treatments for contact lens wearers (and non-wearers) include education on quality blinking with complete lid closure, the 20-20-20 rule for visual breaks, and workstation design and ergonomics. Frequent lubrication (every one to two hours) with nonpreserved artificial tears can be recommended as well. Additionally, a small desktop humidifier may enhance lubrication of the contact lens/ocular surface system. These treatment options are relatively simple, inexpensive, and quick to implement.

If first-line treatment options do not provide satisfactory relief, practitioners should try to determine the primary etiology of symptoms, if possible. If discomfort, dryness, and/or irritation are primary and symptoms occur even when not using digital devices, CLD is the likely etiology. Patients who have CLD should experience rapid relief when their contact lenses are removed.

Optimizing the contact lens factors listed in Figure 1 is the next step. To review, practitioners should optimize the lens material, design, or fitting characteristics, replacement modality, and/or lens care system.

If optimizing contact lens factors is not successful, the best approach is to remove the lenses and use the spectacle correction for prolonged digital tasks. The spectacles may be computer-specific designs or conventional designs depending on whether patients are presbyopic, the workstation design, and other factors. Although many lens wearers will resist using glasses, they may accept this reality if practitioners have diligently pursued other options in a logical fashion and patients experience significantly improved ocular comfort and vision with glasses after contact lens removal.

If the primary symptoms are visual in nature, such as eye strain or ache, ocular fatigue, and variable blur, DES is likely the primary cause. These symptoms may be present with or without contact lenses. A careful refraction with attention to low astigmatism, uncorrected hyperopia, and presbyopia also is important. Accommodative and binocular vision testing may reveal dysfunction that can be treated with vision therapy and/or spectacle correction. For nonpresbyopic lens wearers, recommending a digital relief (<1.00D add or “relief”) contact lens may relieve accommodative stress and/or infacility. Single-vision computer spectacles with a low add corresponding to the screen distance, used with or without contact lenses, are an excellent option. This allows practitioners to incorporate uncorrected refractive error.

Presbyopic contact lens wearers who have DES have several options. Changing from single-vision to multifocal contact lenses can be gratifying in an early presbyope if prescription parameters are available. For presbyopes who have significant astigmatism, custom multifocal toric soft lenses, multifocal GP (corneal or scleral), and hybrid designs are available. If patients are successfully using multifocal contact lenses under normal conditions but experiencing DES symptoms, the first step is to make sure that the add power is appropriate for the workstation design and visual tasks.

If, despite optimizing the distance and near powers using the current design, the result is still unsatisfactory, changing the design or modality (soft to GP or hybrid) is the next step. If patients are resistant to changing designs or materials, spectacle correction—with or without contact lenses—is the final step. Many patients successfully wearing multifocal contact lenses are open to wearing “computer glasses” with a large intermediate power zone for prolonged reading or digital device viewing.

THE FINAL WORDS

In summary, many (if not most) contact lens wearers use digital devices extensively in their daily lives. The combination of contact lens wear and prolonged viewing of multiple digital screens throughout the day places significant stress on the tear film/ocular surface and the overall visual system. Our job as practitioners is to maximize visual function and ocular physiology by diagnosing and managing CLD and DES before patients drop out of contact lens wear. If first-line treatment options are not satisfactory, practitioners should consider other management options in a systematic fashion. CLS

REFERENCES

1. The Vision Council. Digital Eye Strain. Available at www.thevisioncouncil.org/content/digital-eye-strain . Accessed on Oct. 5, 2018.
2. American Optometric Association. Computer Vision Syndrome. Available at www.aoa.org/patients-and-public/caring-for-your-vision/protecting-your-vision/computer-vision-syndrome . Accessed on Oct. 5, 2018.
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11. The impact of myopia and high myopia: report of the Joint World Health Organization–Brien Holden Vision Institute Global Scientific Meeting on Myopia. 2015 Mar. Available at www.who.int/blindness/causes/MyopiaReportforWeb.pdf . Accessed on Oct. 5, 2018.
12. Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology. Mol Vis. 2016 Jan 24;22:61-72.
13. Leung TW, Li RW, Kee CS. Blue light filtering spectacle lenses: optical and clinical performances. PLoS One. 2017 Jan 3;12:e0169114.
14. Smick K, Villette T, Boulton ME, et al. Blue light hazard: New Knowledge, New Approaches to Maintaining Ocular Health. Report of a roundtable. 2003 Mar 16. Available at www.essilorusa.com/content/dam/essilor-redesign/product-resources/crizal/Blue-Light-Roundtable_White-Paper.pdf . Accessed on Oct. 5, 2018.
15. Vimont C. Should You Be Worried About Blue Light? 2017 Aug 24. Available at www.aao.org/eye-health/tips-prevention/should-you-be-worried-about-blue-light . Accessed on Oct. 5, 2018.