Eye strain

Eye strain is fatigue of the ciliary muscles and extraocular muscles. Eye strain does not cause myopia, but it can lead to pseudomyopia.

The ciliary muscles control focus by changing the shape of the lens. Looking at near objects for extended periods of time strains the ciliary muscle, leading to a ciliary spasm. This muscle is most relaxed when looking far in the distance and when sleeping.

Extraocular muscles control the movement of the eye and the eyelid. These muscles may tighten during intense visual work or when the body perceives a threat. When tightened, a person may appear to be scowling or squinting. Closing the eyes and massaging around the eye can temporarily relax these muscles, but they will quickly tighten again if the core problem is not addressed with better habits.

Uncorrected vision is a cause of eye strain.