Eye

Eye anatomy begins with the cornea, a clear dome that bends incoming light toward the pupil. The iris, a ring of muscle that gives eyes their color, widens or narrows the pupil to control how much light enters. Behind the pupil sits the lens, a flexible disc that changes shape to focus nearby or distant objects on the retina.

The retina lines the back of the eye and contains two main photoreceptors: rods for dim light and cones for color and detail. Signals from these cells travel through layers of neurons and exit via the optic nerve. The brain stitches together information from both eyes to judge depth, track motion, and recognize faces.

Tears and eyelids protect the eye's delicate surface. Each blink spreads a thin film of moisture enriched with antibodies to remove dust and microbes. The sclera, or white of the eye, forms a tough shell, while extraocular muscles anchor to it and move the gaze smoothly in any direction.

Vision depends on precise focusing. When the eyeball is too long, images land in front of the retina, causing myopia; when it is too short, hyperopia results. Astigmatism arises from uneven curvature. Optometrists correct these refractive errors with glasses, contact lenses, or refractive surgery that reshapes the cornea. Regular exams also monitor for glaucoma, cataracts, macular degeneration, and diabetic retinopathy, conditions that can quietly damage vision.

Lifestyle choices support ocular health. Balanced diets rich in leafy greens, omega-3 fats, and vitamins A and C nourish the retina. Breaks from screens reduce digital eye strain, while sunglasses block ultraviolet radiation that can cloud the lens. Advances such as retinal implants, gene therapy, and artificial tears promise new options for people with inherited or acquired eye disorders.