Question

a simplified model of the eye is made up of pupil, a crystal lens and a retina. but what is the optical component corresponding to the crystal lens?

Answer 1

ANSWER
The optical components are transparent elements that admit, bend, and focus light onto the cells of the retina to form images. This occurs through the process of refraction, so the optical components are also known as refractile media components.

These components are:

The cornea

The cornea acts as the main window of the eye. This is the major refractive element of the eye.

Aqueous humour

The aqueous humour is a watery fluid in the anterior and posterior chambers that is secreted by the ciliary body. Its role in refraction is relatively minor, but it is important in providing nutrients to the lens and cornea, which do not have the means to support themselves, and are the two critical refractile elements.

The lens
The lens is second most in importance to the cornea in the refraction of light rays. It is elastic, so that the shape of the lens can undergo minor changes in response to tension of the ciliary muscle. Tension on the muscle flattens the lens, whereas it relaxes into a more spheroid shape when it is not under tension. These changes allow for accommodation to allow proper focusing on near objects.