Using your eyes for a long period of time or for visually intense tasks can make them feel fatigued and lead to a condition referred to as eye strain, or its medical term, asthenopia. Eye strain is a group of symptoms, not a disease. Some activities that may lead to eye strain, typically from driving a car on long trips, prolonged reading, close detailed work, hours on the computer or looking at other type of screens. Eye strain can be a common, regular occurrence for people who work in a job that requires long, intense periods of visual focus.   

The increased use of digital screens and eye strain have led physicians to use a more specific term to describe this type of eye strain, Computer Vision Syndrome (CVS). People are at a greater risk for CVS if they look at digital screens for more than two hours each day, for consecutive days. A study found that 90% of the 70 million Americans that use computers at work, for more than 3 hours per day, experience some form of CVS. [2]

Although it can be uncomfortable and unpleasant, eye strain is not a serious health concern, and often resolves once your eyes have had an opportunity to rest.  In adults, there is no evidence that eye strain leads to any damage, injury or long-term negative consequences to your eyes.   

 

What are the symptoms of Eye Strain?

Symptoms of eye strain may present in a variety of ways and for some people they can be disruptive to concentration and performing certain tasks. People with eye strain may experience some, or all, of the following symptoms [3]:

• Eyes feeling heavy
• Eyes having a burning sensation
• Eyes feeling itchy
• Eye ache or pain
• Excessing watering or tearing of eyes
• Unable to keep eyes open
• Blurred vision
• Sensitivity to light (photophobia)
• Double vision

Double vision often occurs when the task that caused the eye strain involves near work. This is because when focusing intensely on near activities, the eyes must have good accommodative capacity, meaning that the eye muscles must work together (binocularity), and work harder to focus.  

Squinting can also lead to eye strain because the muscles around the eye "squint", to either block out brightness or trying to improve eye focus.   

Eye strain can also cause body-wide symptoms: 

• Headache
• Neck or back pain
• Nausea
• Fatigue or sleepiness
• Difficulty concentrating

These symptoms often occur when concentrating on intense visual tasks. Without necessarily being aware of it, some people tighten or clench the muscles in their face, neck, shoulders, or jaw.   

The symptoms of eye strain are quite broad and may point to underlying eye disorders, so having a periodic eye examinations is always recommended.  

Eye strain is typically only experienced by adults as it is rare for children under 12 to have these symptoms. If they do, they should have a complete eye examination to check for any underlying eye conditions especially corrective lenses and visual training.

Risk Factors for Eye Strain

Rather than health-related factors, it's usually the activity and duration of that activity that increase risk of eye strain. Studies have shown that people that who spend most of their waking hours doing visually stressful activities like driving, computer gaming or are exposed to high glare digital screens are at a greater risk of developing symptoms of eye strain. Lack of sleep, certain medications, auto-immune disease, or high stress, can worsen the symptoms.

 

People with jobs requiring full time computer use, or intense and sustained periods of visual focus are more prone to experiencing eye strain symptoms. [4] Lawyers, accountants and radiologists are susceptible professionals. [6] Radiologists are medical doctors that diagnose and treat disease by utilizing medical imaging techniques such as x-rays, computed tomography (CT), and magnetic resonance imaging (MRI). This is a profession that requires a prolonged focus on very detailed objects, viewed close to the eyes.

Older people are spending increasingly more time reading or on a computer than they previous generations, are also at increased risk for eye strain. As we age, the eye’s ability to accommodate or focus (using neuromuscular energy), which is the reason older people find it difficult to read small print close up or in dim light without the assistance of reading glasses. This population also experiences a higher incidence of dry eye syndrome which has similar symptoms to eye strain. The two conditions may intensify each other.  

Some people experience eye strain when they have been spending longer periods outside without proper eye protection, such as sunglasses or tinted contact lenses and spectacles, particularly in bright or high glare environments.  

If you have a refractive error (near or far sightedness or astigmatism) and need corrective lenses, like glasses or contact lenses, you can experience eye strain symptoms as you may squint more and your eyes may have to work harder to enable you to see clearly.   

Some common medications including Adipex® (obesity), Enduron® (hypertension), Norpramin® (depression) and Xanax® (anxiety), among others, may cause poor accommodative capacity and difficulty focusing, leading to eye strain.  

An eye muscle imbalance, meaning that the eyes do not work well together, or poor accommodative capacity, may cause symptoms of eye strain.  

 

How is Eye Strain Diagnosed?

Accommodative and binocular vision testing during an eye exam can positively diagnose eye strain and measure or assess its degree of intensity. eye strain is often diagnosed once you have shared a thorough history, and any other serious eye conditions have been ruled out with your doctor.

 

Lenses, lighting, filters, ergonomic recommendations and nutritional supplements can all be helpful

Although the majority of people experience eye strain at some time or another, most people do not inquire about medical treatments. Lenses, lighting, filters, ergonomic recommendations and nutritional supplements can all be helpful. There are tips and recommendations for how to change your behavior to manage eye strain symptoms, as it usually resolves with rest.  

Some ways to manage, or lessen the symptoms of eye strain include:

• Practice the 20/20/20 method – for every 20 minutes you are using a computer or intensely focused on a screen, it is recommended to shift your focus to something at a far distance (at least 20 feet away) or close your eyes for 20 seconds. 
• Check your glasses or contact lenses - Needing glasses or an updated glasses prescription can lead to eye strain. Wearing glasses with an incorrect prescription may increase the intensity of symptoms. 
• Increasing the font size – adjust your computer settings to increase the size of the display font.  
• Reduce glare – adjust your digital screen settings to reduce the screen brightness level to reduce glare or request that special anti-reflective coatings be added to the lenses of your glasses when they are being made.
• Blink more frequently and completely – Studies have shown that during intense concentration and computer or smartphone use, people tend to blink less frequently and do not blink fully, which does not provide the eye with adequate moisture and lubrication. Research has shown that people blink 17 time per minute during conversation, which is significantly reduced to only six times per minute while reading. [5] Studies have also reported that the use of digital devices increases the rate of incomplete blinks (not completely closing and opening eyes) to 15%. [1] Blinking provides the eye with a natural refresh. Some people find that the use of artificial tears can also be helpful. 
• Good light sources – Trying to see something in dim light can cause eye strain. Ensure that when performing near tasks or close work that you have sufficient light to see properly. 
• Check your environment – Some people find that increasing the humidity in their environment and limiting circulated air (fans or air conditioners in home, office or vehicle) can lessen the intensity of eye strain symptoms through avoidance of dry eye.  

Some people are told that they have poor accommodative capacity (their eye muscles are not working sufficiently) will benefit from an eye exercise, called “pencil push-ups”. While wearing your glasses or contact lenses, if you have been prescribed them, hold a pencil upright about 12 inches in front of your nose. If you are able to clearly see the tip of the pencil, then slowly bring it closer to your nose. As you bring it nearer, the tips of the pencil may become blurry or appear to split into two (double vision). The objective of the exercise is to try to hold clear focus on the pencil tip as it gets closer to your nose. Hold the focus for three seconds, then move the pencil back and let your eyes relax. It is recommended to repeat this exercise ten times. Performing this exercise will likely cause your eye muscles to feel strained, much like exercising your other muscles. It is thought that consistently performing this exercise and increasingly your ability to focus on the pencil tip closer and closer to your nose will improve your ability to accommodate or focus for prolonged periods of time on near activities.  

 

References:  

[1] Argilés M, Cardona G, Pérez-Cabré E, Rodríguez M. Blink Rate and Incomplete Blinks in Six Different Controlled Hard-Copy and Electronic Reading Conditions.  Invest Ophthalmol Vis Sci. 2015 Oct;56(11):6679-85. https://www.ncbi.nlm.nih.gov/pubmed/26517404

[2] Blehm C., Vishnu S., Khattak A., Mitra S., Yee R. W. (2005). Computer vision syndrome: A review. Survey of Ophthalmology, 50, 253-262. https://www.ncbi.nlm.nih.gov/pubmed/15850814

[3] Long J, Cheung R, Duong S, Paynter R, Asper L. Viewing distance and eyestrain symptoms with prolonged viewing of smartphones. Clin Exp Optom. 2017 Mar;100(2):133-137. https://www.ncbi.nlm.nih.gov/pubmed/27716998

[4] Randolph SA. Computer Vision Syndrome. Workplace Health Saf. 2017 Jul;65(7):328. https://www.ncbi.nlm.nih.gov/pubmed/28628753

[5] Schlote T, Kadner G, Freudenthaler N. Marked reduction and distinct patterns of eye blinking in patients with moderately dry eyes during video display terminal use. Graefes Arch Clin Exp Ophthalmol. 2004 Apr; 242(4):306-12. https://www.ncbi.nlm.nih.gov/pubmed/14747951

[6] Stec N, Arje D, Moody AR, Krupinski EA, Tyrrell PN. A Systematic Review of Fatigue in Radiology: Is It a Problem? AJR Am J Roentgenol. 2018 Apr;210(4):799-806. https://www.ncbi.nlm.nih.gov/pubmed/29446673