Question

features and parts of eye ?

Answer 1

Explanation:

The sclera, or white part of the eye, protects the eyeball. ... The cornea, a clear window at the front of the eye, covers the iris and the pupil. A clear lens, located behind the pupil, acts like a camera lens by focusing light onto the retina at the back of the eye.

Answer 2

hey mate...

here is your answer ...

Sclera

The sclera is the white of the eye. "Don't shoot until you see their scleras."

Exterior is smooth and white

Interior is brown and grooved

Extremely durable

Flexibility adds strength

Continuous with sheath of optic nerve

Tendons attached to it

The Cornea

The cornea is the clear bulging surface in front of the eye. It is the main refractive surface of the eye.

Primary refractive surface of the eye

Index of refraction: n = 1.37

Normally transparent and uniformly thick

Nearly avascular

Richly supplied with nerve fibers

Sensitive to foreign bodies, cold air, chemical irritation

Nutrition from aqueous humor and

Tears maintain oxygen exchange and water content

Tears prevent scattering and improve optical quality

Anterior & Posterior Chambers

The anterior chamber is between the cornea and the iris

The posterior chamber is between the iris and the lens

Contains the aqueous humor

Index of refraction: n = 1.33

Specific viscosity of the aqueous just over 1.0 (like water, hence the name)

Pressure of 15-18 mm of mercury maintains shape of eye and spacing of the elements

Aqueous humor generated from blood plasma

Renewal requires about an hour

Glaucoma is a result of the increased fluid pressure in the eye due to the reduction or blockage of aqueous from the anterior to posterior chambers.

Iris/Pupil

Iris is heavily pigmented

Sphincter muscle to constrict or dilate the pupil

Pupil is the hole through which light passes

Pupil diameter ranges from about 3-7 mm

Area of 7-38 square mm (factor of 5)

Eye color (brown, green, blue, etc.) dependent on amount and distribution of the pigment melanin

Lens  

Transparent body enclosed in an elastic capsule

Made up of proteins and water

Consists of layers, like an onion, with firm nucleus, soft cortex

Gradient refractive index (1.38 - 1.40)

Young person can change shape of the lens via ciliary muscles

Contraction of muscle causes lens to bulge

At roughly age 50, the lens can no longer change shape

Becomes more yellow with age: Cataracts

The graph on the right shows the optical density (-log transmittance) of the lens as a function of wavelength. The curves show the change in density with age. More short wavelength light is blocked at increases ages.

Vitreous Humor

Fills the space between lens and retina

Transparent gelatinous body

Specific viscosity of 1.8 - 2.0 (jelly-like consistency)

Index of refraction, n=1.33

Nutrition from retinal vessels, ciliary body, aqueous

Floaters, shadows of sloughed off material/debris in the vitreous

Also maintains eye shape

hope it helps...