Page 13 - The Book Pi in eye

Pi in eye

Figure 1.2 Normal eye focuses on single image on retina.

Unlike the camera, the human eye is a biological tissue and needs
nutrients to survive. Yet the central portion must be kept clear so
that there is no interference with light. Blood vessels normally supply
these nutrients to other parts of the body. However, they cannot be
used for this particular function for the cornea or the lens, because
blood vessels would interfere with light and vision.
This brings us to yet another physiological marvel. Tears, and the
liquid inside the eye supply nutrients to the clear cornea and the lens.
Nutrient waste is then also carried by a similar mechanism.
Therefore, anything, which affects the harmony of this carefully
crafted and delicately balanced system, can affect our vision.

Errors of Refraction

We have seen that the photons of light have to converge on the
macula at the center of the retina, at a single spot to enable
visualization. If there are any errors in the optical system the light
may not come to focus at the required spot.
If the light comes to focus at a single spot in front of the retina,
this is termed as myopia or near sightedness. The person will be able
to see things at a close distance but unable to see far.

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