All the different parts of your eyes work together to help you see. It requires immediate medical attention. Multiple genes inherited from each parent determine a person’s eye color. At the front of the eyeball, the sclera becomes the cornea. Slit lamp examination: A physician or optometrist shines a vertical slit of light across your eye while looking through a microscope. Your doctor uses it to check for glaucoma. It converts light into electrical impulses. Your brain may favor one eye. The lacrimal glands are almond-shaped glands that sit in the superolateral (upper outer)  part of the orbit. The posterior segment which accounts for the other 80% of the inner eyeball lies between the posterior surface (back) of the lens and the retina. It then drains into the nasal cavity where it is swallowed. Cyclosporine eye drops (Cequa, Restasis): This anti-inflammatory eye drop can treat dry eye caused by inflammation. Some of this light enters the eye through an opening called the pupil (PYOO-pul). The human eye consists of the eyeball, optic nerve, orbit and appendages (eyelids, extraocular muscles and lacrimal glands). It is made up of many different parts working in unison together. Regular adult eye exam: This collection of tests may include the ones mentioned above plus others, like eye movement. When the ciliary muscle contracts or relaxes, the tension on the lens increases or decreases. The lacrimal glands have about 10 excretory ducts that carry fluid out of the glandular substance onto the outer surface of the eyeball. The outer fibrous layer maintains the shape of the eyeball and protects more fragile internal structure. Fovea The center of the macula which provides the sharp vision. It can happen when your eye is “too short” for the lens to focus light the way it should. The selected Eye Diagrams are plotted. If it happens to a kid, it can decrease vision in the other eye. Right suspensory ligament of eyeball. It is approximately 25 mm in diameter and sits snugly in the orbit where six muscles control its movement. Contact lenses and glasses: They correct common eye problems like nearsightedness, farsightedness, and astigmatism. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails. Double-click again to view all plots. The inner lining of the eyelid is lined with a thin mucous membrane known as the palpebral conjunctiva which then reflects onto the eyeball where it covers the outer layer and is known as the bulbar conjunctiva. Corneal abrasion: A scratch on the clear part of the front of your eye (called the cornea). Black eye: Swelling and discoloration (bruise) around your eye caused by an injury to the face. The structure of the human eye is such that light can enter, be refracted and trigger nerve impulses back to the brain which are then deciphered as images. Tonometry: A test that measures pressure in the eye, called intraocular pressure. Eye Structures (Front and Side Views) The conjunctiva is the mucous membrane that lines the eyelid and eye surface. Size and shape: Human eye is spherical about 2.5 cm in diameter. (Source: Wikipedia, credit: Gmoose1.) Pterygium: A thickened mass usually on the inner part of the white part of your eyeball. Refraction: If you have a vision problem, the doctor will place a series of lenses in front of each eye, one at a time, to figure out your prescription for corrective lenses. Your eye is a slightly asymmetrical globe, about an inch in diameter.