Question

Draw a labelled sketch showing how the eye works and which parts of the eye see variations of contrast, color and detail (include rods and cones in your sketch). What does the “blind spot” mean and where is it in the eye? Does the eye see an upright or an inverted image? How does the lens of the eye work? Is the lens static?

Answer 1

Eye adjusts the light focusing by means of refraction. Every part of the eye refracts (or bends) light by different amounts. Most refraction occurs in the cornea because it is curved. However, this always bends it by the same amount, therefore we adjust the shape of the lens to vary the refractive index to focus light on the retina.

In the retina are cells responsible for detecting light, and sending this information to the brain. There are two types of cell, the rod, and cone. Rod cells are responsible for detecting light/dark . Cone cells are responsible for details and color. It has 3 basic cones. red, green, blue . It is possible to see different colors by the stimulating of different combinations.

A blind spot is a small area of the retina where the optic nerve enters the eye; this type of blind spot occurs normally in all eyes. Any gap in the visual field corresponding to an area of the retina where no visual cells are present.

The images formed on retina are always upside down (inverted).

Working of lens is a standard answer. The lens is a biconvex disc that causes light to converge onto the retina. Its shape can be adjusted by the ciliary muscle to allow focusing on near and far objects. The lens focuses light through the vitreous humor, a clear gel-like substance that fills the back of the eyeand supports the retina. The retina receives the image that the cornea focuses through the eye's internal lens and transforms this image into electrical impulses that are carried by the optic nerve to the brain