Hole in the iris that becomes wider in dim light, it is the adjustable gateway for light.
Pupil
The lens is surrounded by these hard-working muscles that are used alter its shape.
Ciliary muscles
This eye disease is caused due to high pressure built up by too much fluid.
Glaucoma
In farsightedness, light rays converge behind the retina causing a blurred image. Can be corrected with a convex lens and is also called this.
Hyperopia/Hypermetropia
This disease, common in older people, is characterized by the normally transparent lens becoming cloudy due to the change in protein fibers.
Cataract
A little envelope of fluid the size of a vitamin pill, it is a transparent disk of tissue that changes shape for near or far vision. Used for fine-focusing the light rays.
Lens
Dime-sized transparent window at the front, it starts the seeing process by bending light rays into orderly patterns.
Cornea
In nearsightedness, the eyeball is too longs and the light rays focus in front of the retina necessitating concave lens. Also called this.
Myopia
7 million receptor cells in the retina that are used for color vision.
Cones
These glands secrete tears to keep the eye moist.
Lacrimal glands
Ring of muscle that changes the size of pupil to regulate the amount of light entering the eye.
Iris
Called the white or white of the eye, it is the opaque (usually white, though in certain animals, such as horses and lizards, it can be black), fibrous, protective, outer layer of the eye containing collagen and elastic fibers.
Sclera
This is caused by the cornea distorting vision because of its irregular curvature. So the lens of the eye is unable to bring all light rays into correct focus on the retina.
Astigmatism
The common name for the condition called 'Strabismus' in which the eyes are not properly aligned with each other.
Squint-eye
130 million receptor cells in the retina that are used for black-and-white vision.
Rods
It is the connecting nerve from the eye to the brain.
Optic nerve
A type of refractive laser eye surgery performed by ophthalmologists for correcting myopia, hyperopia, and astigmatism. Many patients choose it as an alternative to wearing corrective eyeglasses or contact lenses. The procedure is generally preferred to photorefractive keratectomy, PRK, (also called ASA, Advanced Surface Ablation) because it requires less time for the patient's recovery, and the patient feels less pain.
LASIK
Also known as visual purple, it is a pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light.
Rhodopsin
Region of retina with dense concentration of cone cells, for enabling precise vision.
Fovea
Thin layer of light sensitive rod and cone cells that acts as a wallpaper where light is focussed on by the lens.
Retina