The lacrimal gland is located under the upper eyelid. It secretes tears. The lacrimal canals, present in the lower eyelid, allow the evacuation of the tears towards the nose.
The cornea and the lens
The cornea is a transparent, dome-shaped structure through which light enters the eye. The crystalline lens is the natural lens of the eye. It is located behind the iris. Variations in the curvature of the crystalline lens allow for the focusing of close-up objects. This phenomenon is called accommodation.
The retina, macula and papilla
The retina is the inner membrane that lines the eye. A tiny area in the center of the retina, called the macula, is responsible for accurate vision such as reading, watching television and driving. Millions of nerves leave the retina and meet at a point called the papilla, where the optic nerve originates. This nerve connects the retina to the brain.
How the eye works
The iris regulates the amount of light that enters the eye through the cornea and then the pupil. The cornea and the lens focus the light rays on the retina.
These are transformed into electrical impulses that are carried by the optic nerve to the brain, where they become the images you see.
Light rays pass through the cornea and converge on the retina. Objects appear clearly, regardless of their distance.
Myopia is the result of an eyeball that is too long. As light rays converge in front of the retina, distant objects appear blurred.