Physics » Vision and Optical Instruments » Physics of the Eye

# Summarizing Physics of the Eye

## Physics of the Eye Summary

• Image formation by the eye is adequately described by the thin lens equations:

$$P=\cfrac{1}{{d}_{\text{o}}}+\cfrac{1}{{d}_{\text{i}}}\phantom{\rule{0.25em}{0ex}}\text{and}\phantom{\rule{0.25em}{0ex}}\cfrac{{h}_{\text{i}}}{{h}_{\text{o}}}=-\cfrac{{d}_{\text{i}}}{{d}_{\text{o}}}=m.$$

• The eye produces a real image on the retina by adjusting its focal length and power in a process called accommodation.
• For close vision, the eye is fully accommodated and has its greatest power, whereas for distant vision, it is totally relaxed and has its smallest power.
• The loss of the ability to accommodate with age is called presbyopia, which is corrected by the use of a converging lens to add power for close vision.

## Glossary

### accommodation

the ability of the eye to adjust its focal length is known as accommodation

### presbyopia

a condition in which the lens of the eye becomes progressively unable to focus on objects close to the viewer

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