Asthenopia, also known as eyestrain, is an ocular condition which is seen frequently amongst students and computer operators. It is caused by long hours of near work leading to eye fatigue. Asthenopia can be of either the accommodative type or the muscular type and the two types can be differentiated with a patch test.
Asthenopia is becoming a public health problem due to lifestyle changes and increasing usage of computers in colleges and various industries  . The term asthenopia includes several different clinical manifestations arising secondary to the excessive use of eyesight   . The symptoms are found to have a female preponderance with high school students presenting with ocular symptoms more frequently compared to primary school children due to their increasing use of computers . Specific ocular clinical manifestations are photophobia, blurring of vision, eye redness, diplopia, itching of eyes, excessive tearing, dry eyes, and foreign body sensation  . Other symptoms include headaches, eye soreness, fatigue, and irritation    . Severe symptoms of asthenopia have been reported to accelerate age-related ocular diseases , reduce productivity and quality of life  . Factors postulated to have a strong association with asthenopia include computer usage, psychosocial status, environment conditions, posture, and diet.
Asthenopia is classified as either internal or external .
Clinical presentation of asthenopia is similar to various other ocular disorders posing clinicians and optometrists with diagnostic challenges  . Evaluation of patient's symptoms along with clinical measures helps to diagnose the condition and plan further management. The workup should start with a detailed history to elicit eyestrain at the college or work, refractive errors, use of spectacles or contact lenses, and previous laser surgery to correct refractive errors. An ophthalmological examination is essential to evaluate tear film, corneal opacities, and refraction. Visual acuity test, cycloplegic refraction test, and fundoscopy must be performed in all cases of asthenopia. The cover or patch test helps to confirm the diagnosis of asthenopia and differentiate between the two types of asthenopia. Persistence of symptoms after patching one eye for several hours indicates accommodative stress while relief of symptoms after resting one eye indicates muscular incompetence. Tests to differentiate accommodative insufficiency from ocular myasthenia gravis such as the Tensilon test, acetylcholine receptor antibody titers, and single fiber electromyography (EMG) testing can also be performed.
Laboratory and radiological studies are usually not indicated during the workup.
Scheiman M, Wick B. Clinical management of binocular vision: Heterophoric, accommodative and eye movement disorders. 3rd ed. Philadelphia, PA: JB Lippincott; 2008.