Digital Eye Strain (Computer Vision Syndrome)

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What are the symptoms of computer vision syndrome?

What are the causes of digital eye strain and how can it be prevented?

Does blue light contribute to computer vision syndrome?

Introduction

Digital devices like computers, laptops, smartphones, tablets, e-readers, and others have become an inseparable part of our lives. They have intruded on our professional as well as our personal lives. However, prolonged use of these electronic gadgets can have negative effects on our health. One such effect is the ‘computer vision syndrome’ or CVS. However, this term is not appropriate, as the effects are not only due to computers but other digital devices like mobiles as well. Hence, a more appropriate term for this condition is ‘digital eye strain’ or DES.

The magnitude of this problem is huge. Two studies conducted in the UK and USA in 2016 found that adults typically spend around 5 hours on digital devices. Hence, this issue needs to be addressed on a priority basis.

What are the symptoms of computer vision syndrome?

Diagnosis of computer vision syndrome is usually based on clinical symptoms. The symptoms of digital eye strain can be broadly divided into two groups as suggested by the study of Sheedy and colleagues in 2003: those that are related to excessive use of the muscles involved in eye function and those related to the drying of the eyes.

Symptoms due to excessive use of eye muscles

eye strain/discomfort/ache or even pain
eye fatigue/tired eyes,
headache behind the eyes,
blurred/double vision, and
difficulty refocusing from one object to the other.

Symptoms due to drying of eyes

eye irritation or burning sensation,
excessive tearing, and
red/bloodshot eyes.

The symptoms of computer vision syndrome are usually temporary and can be reduced by appropriate measures.

What are the causes of digital eye strain and how can it be prevented?

The causes of computer vision syndrome can be divided into three groups:

Personal
Device related
Environmental

Personal factors

Eye strain and fatigue are due to increased workload of eye muscles

The first component involved in computer vision syndrome is the increased load on the muscles of the eye. This is because working on digital devices requires focusing on digital screens for prolonged periods. To relieve eye strain and fatigue, the American Optometric Association (AOA) advocates the 20-20-20 rule. As per this rule, it is advised to take a break of 20 seconds after every 20 minutes of working on digital devices to look at a distant object located 20 feet away. This intervention relaxes the muscles of the eye and reduces symptoms due to eye muscle strain. It also gives the tired eye muscles a short period of rest.

Infrequent blinking and incomplete blinks can cause drying of the eyes

Frequent and complete blinking of the eye is important as it spreads the film of tear throughout the outer surface of the eye. Tear performs important functions like preventing dryness of the eye, lubricating the eye as the eyelids move over the surface of the eye, preventing irritants to come in direct contact with the eye, and disinfecting the eye. Numerous studies (like Nakamori and colleagues in 1997, Patel and colleagues in 1991, and many more) found that people focusing on screens of digital devices blink less frequently. Furthermore, studies by Chu and colleagues in 2014 and Argiles and colleagues in 2015 found that digital device users had more incomplete blinks. Both less frequent and incomplete blinking contribute to drying of eyes.

Lubricating eye drops and omega 3 fatty acids can provide relief in computer vision syndrome

Lubricating eye drops can reduce symptoms due to infrequent and incomplete blinking and provide relief from symptoms. A study by Bhargava and colleagues in 2015 found that omega 3 fatty acids reduced the tear evaporation rate and improved the symptoms due to dry eyes. Blink training (to blink frequently and completely) given to users of digital devices may help to reduce the symptoms due to dry eyes.

Contact lens wear can worsen the symptoms of digital eye strain

Two studies by Tauste and colleagues (in 2014 and 2016) found that computer vision symptoms were more common in contact lens users.

Errors of refraction can worsen the symptoms of digital eye strain

Some people have pre-existing errors of refraction like myopia (or nearsightedness) or hyperopia (or farsightedness). Others have astigmatism when the shape of the cornea or lens is not perfect. The fourth condition is presbyopia, in which people more than 40 years of age gradually lose the ability to focus near objects. In all these 4 conditions, images are not focused properly on the retina. As a result, they experience symptoms like blurred vision. All these 4 conditions make the condition of computer vision syndrome worse. Hence, it is necessary to get the eyes checked for these conditions and correct them if they are present.

Age was linked to dry eyes’ symptoms

A study by Uchino and colleagues in 2013 found that dry eyes related symptoms were more common in people more than 30 years of age.

Women can more frequently experience symptoms of computer vision syndrome

Two studies, one by Portello and colleagues in 2012 and the other by Toomingas and colleagues in 2014, showed that women more commonly had eye symptoms as compared to men. Another study by Uchino and colleagues in 2013 showed that women more commonly experienced symptoms related to dry eyes as compared to men.

Nicotine use (like smoking) can aggravate symptoms of digital eye strain

The study by Toomingas and colleagues in 2014 also found a higher association of eye symptoms with nicotine use.

Device related factors

Digital screen distance and placement can impact digital eye strain symptoms

The distance and viewing angle of the monitor should be such that it should provide the most comfortable viewing experience with minimal eye strain. According to a study by Jaschinski and colleagues in 1999, shorter viewing distance and higher monitor placement increases eye strain and consequently causes the eyes to tire much faster. According to this study, a screen distance of 60 to 100 cm and placement at a vertical down gaze of 0° to -16° was preferred by the participants in the study.

Few studies have suggested optimal viewing distances for certain types of devices. A distance of 32.2 cm was recommended for smartphones according to a study by Bababekova and colleagues in 2011. This is because smartphones have smaller font sizes, and can be view comfortably only at shorter distances. For e-readers, a minimum of 50 cm was recommended in a study by Shieh and colleagues in 2007. For computer monitors, an optimal viewing distance of 50 to 63.5 cm was recommended by a study by Ankum and colleagues in 1996.

Keeping the screen at a level lower than the eyes has another advantage. When the monitor is kept at the level of the eye, the eyelids are completely open and the entire surface of the eye is exposed. This causes the tear film to evaporate faster. However, when the monitor is kept at a slightly lower level than the eye, the eyelids partly cover the eye, and tear evaporation is slower.

Screen resolution, background and text color (contrast), and font types and sizes can affect computer vision syndrome symptoms

Lower resolution screens increase the workload on the eyes. Viewing on high-resolution screens is not only comfortable but provides an overall better viewing experience. There should be sufficient contrast between the text and the background color. If the contrast is not sufficient, eyes need to work that much harder to read the text. A good contrast is provided by a black text against a white background and vice versa. Certain font types like the san serif fonts are easier to read than serif fonts. Vertical fonts are easier to read than diagonal fonts. Smaller font sizes also put extra strain on the eyes.

Environmental factors

As per a study by Sheedy and colleagues in 1992, environmental factors account for nearly a third of symptoms associated with digital eye strain.

Reflections from the digital screens can increase eye strain

Bright lights and various objects placed in the vicinity of the digital devices are reflected from the screens. This increases the eye strain. A study by Flynn and colleagues, 1999, found that anti-glare coating reduces these reflections, and makes viewing more comfortable.

Longer working hours can aggravate the symptoms of computer vision syndrome

Long working hours led to more symptoms of digital eye strain according to a study by Toomingas and colleagues in 2014. The effect was found to worsen proportionately to the number of years involving work on digital devices. Thus, a cumulative effect was suggested by the study by Shimai and colleagues in 1986.

Surrounding temperature, humidity, and air draft can have an impact on the symptoms of digital eye strain

Higher surrounding temperature, humidity, and air draft can cause the tear film to evaporate much faster and worsen the symptoms due to the drying of the eyes. Thus, these conditions can be optimized (with moist and cool air) to reduce the symptoms due to the drying of the eyes.

Does blue light contribute to computer vision syndrome?

Very few studies have been done trying to evaluate the role of blue light in digital eye strain. Most of these studies have been carried out on a small number of study participants. Hence, the results should be interpreted with caution. Of mention are studies by Isono and colleagues in 2013, Ide and colleagues in 2015, and Lin and colleagues in 2017, all of which suggest that blue light can contribute to the symptoms of digital eye strain.

To read a detailed article on other health effects of blue light (including disruption of sleep and the potential for eye damage), click here.

To check the comparison of the top 10 blue light blocking glasses available on Amazon, click here.

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Summary

Digital Eye Strain (DES) or Computer Vision Syndrome (CVS) is a common condition seen in people working with digital devices. Symptoms are those related to eye muscle strain and fatigue (like eye ache and tired eyes, headache behind the eyes, blurred vision, and difficulty focusing) and those related to drying of eyes (like eye irritation, excessive tearing, and redness of the eyes). Several factors are responsible for digital eye strain. These factors can be corrected or their effects can be minimized by measures like the 20-20-20 rule, lubricating eye drops, blink training, increasing intake of omega 3 fatty acids, avoiding the use of contact lenses, correcting errors of refraction, reducing nicotine use, optimizing monitor distance and placement, increasing screen resolution, using good screen contrast, using certain types of fonts, avoiding small font size, using an anti-glare coating on devices, and certain other measures.

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