Cornea
The transparent front part of the eye covers the iris, pupil, and anterior chamber. It acts as a powerful fixed lens and contributes most of the eye’s focusing power, although the focus is fixed. Its refractive power is ~44 dioptres.
Anterior chamber
Fluid-filled space inside the eye between the iris and the cornea’s innermost surface. It is filled with thick watery fluid, aqueous humor. The aqueous humor is constantly circulating through the anterior chamber. It is produced by a tiny gland, situated behind the iris. It flows between the iris and the lens and, after nourishing the cornea and lens, flows out through a very tiny spongy tissue, called the trabecular meshwork, which serves as the drain of the eye.
Iris
A colored, thin, circular structure is responsible for adjusting the diameter of the pupil depending on the intensity of the light, thus, regulating the amount of light going through it.
Pupil
The opening is located in the center of the iris of the eye allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed inside the eye.
Lens
The lens is a clear, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. Its refractive power is about 18 dioptres. But, unlike cornea, which is fixed, the lens, by changing its shape with help of ciliary muscle, helps the eye to focus on objects at various distances, thus allowing a sharp image to be formed on the retina. This adjustment of the lens is called accommodation.
Retina
The light-sensitive tissue lining the inner back surface of the eye. The retina converts light into electrical and chemical events that send impulses to the brain through the optic nerve.
Macula
Is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. Macula is responsible for central vision.
Fovea
Is a part of the eye, located in the center of the macula region of the retina. The fovea is responsible for sharp central vision and contains a high density of photoreceptors with high acuity.
Optic nerve
A bundle of more than a million nerve fibres that carries information about image from the retina to the brain.
