eyesight

Eyesight is the ability to interpret visual information from the environment through the eyes and the brain. It includes visual acuity, fields of view, color perception, and depth perception. The eye works like a camera: light enters through the cornea, passes the pupil and lens, and focuses on the retina, which has photoreceptors called rods and cones. Rods enable vision in dim light and peripheral vision; cones enable color and detail and are concentrated in the fovea. Photoreceptors convert light into electrical signals that travel via the retina to the optic nerve and onward to visual areas in the brain, especially the occipital lobe. The brain combines input from both eyes to form a single image and depth perception.

Visual acuity is often measured with the Snellen chart, and visual fields describe the full area seen without moving the eyes. Normal eyesight depends on healthy eyes and intact neural pathways; problems can result from refractive errors, lens opacity, optic nerve damage, retinal diseases, or neuro-visual disorders.

Common refractive errors include myopia, hyperopia, astigmatism, and presbyopia, usually corrected with glasses, contact lenses, or refractive surgery. Other conditions are cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy. Eye care emphasizes protection from injury, regular exams, management of systemic diseases, and addressing age-related changes. Prevention includes protective eyewear and good nutrition, though evidence varies.