Eye strain

Eye strain, also medically termed as asthenopia (from astheno- 'loss of strength' and -opia 'relating to the eyes'), is a common eye condition characterized by non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and occasional double vision.

Eye strain
Other names	Asthenopia, aesthenopia, eyestrain
Specialty	Ophthalmology
Symptoms	Headache, blurred vision, eye discomfort, and light sensitivity

These symptoms tend to arise after long-term use of computers, staring at phone screens, digital devices, reading, or other activities that involve extended visual tasks. Various causes contribute to eye strain, including uncorrected vision problems, digital device usage, environmental factors, and underlying health conditions. When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the ciliary muscles and the extra-ocular muscles are strained, also contributing to the symptoms. These symptoms are broadly classified into external (related to the ocular surface) and internal symptom factors (related to eye muscles).

Eye strain is highly prevalent among individuals engaged in prolonged near-vision tasks such as reading, writing, or digital work, with studies reporting that 50% to 90% of people experience related symptoms. Severe eye strain is linked to greater difficulty performing visual tasks and reduced efficiency in work or daily life.

A systematic review estimated that 69% of individuals experience eye strain symptoms across populations engaged in prolonged near-vision activities. Certain populations were identified as being at higher risk, including university students (76.1%), contact lens wearers (73.1%) and females (71.4%). Both behavioral and biological factors contribute to the development of eye strain.

Treatment involves environmental modifications, visual aids, and taking periodic breaks. The experience of eye strain when reading in dim light has given rise to the common misconception that such an activity causes permanent eye damage.

Symptoms and signs

Eye strain's symptoms can be broken into two groups: Internal Symptom Factors (ISF) and External Symptom Factors (ESF). ESFs consist of symptoms related to dry-eye such as burning and irritation, seemingly linked to the ocular surface. ISFs are related to pain and ache sensations behind the eye and are linked to accommodative and vergence stress, caused by poor visual conditions.

Symptoms of eye strain can include:

• blurred vision
• headache
• sore, irritated, burning, or itching eyes
• dry eyes or watery eyes
• eye discomfort
• difficulty concentrating
• sensitivity to bright lights

Symptoms can be grouped by affected area or underlying mechanism(s):

• ocular surface (dryness, irritation, redness)
• accommodative (difficulty focusing on near objects)
• vergence (misalignment when turning eyes inward or outward)
• extra-ocular (muscle discomfort around the eyes, neck, and shoulders)

The recognition of these categories helps describe eye strain presentations and guide potential interventions.

Causes

Asthenopia can result from various factors. These causes can be categorized as ocular issues, digital use patterns, environmental factors, or underlying health conditions, including:

• Uncorrected refractive errors (astigmatism, hyperopia, anisometropia, etc.)
• Eye movement coordination
• Accommodative and vergence stress
• Glare
• Flickering lights
• Allergy
• Close viewing distance
• Dry-eye
• Fatigue
• Upward gaze
• Prolonged reading from smartphone

Diagnosis

Therapy

Given that asthenopia is caused by different factors, treatment may involve the work environment or visual conditions. One known method of relieving strain of the ocular muscles is taking periodic breaks by closing the eyes and blinking frequently. Often found in connection to Digital Eye Strain (DES), eye strain can be reduced by following the 20–20–20 rule, which consists of looking at something 20 feet away for 20 seconds every 20 minutes.

Structured break schedules are supported by research as an effective strategy to prevent or reduce eye strain. Planned break regimens have been shown to reduce eye discomfort, decrease headaches, and improve ocular accommodation. Short, frequent breaks have been found to reduce visual fatigue more effectively than longer, less frequent ones. This makes scheduled breaks a useful strategy to mitigate eye strain.

In addition to break regimens, environmental adjustments and ergonomics can help reduce eye strain. Adjusting screen brightness and contrast, optimizing ambient lighting, and changing the color of text further improves comfort during prolonged tasks.

See also

• Eye examination
• Light-on-dark color scheme
• Ocular neurosis
• Photophobia
• Vision therapy
• Visual looming syndrome