irregularities of the eye result in a common
clinical condition called presbyopia.
As a result, the vision of the eye is hazy and
must be clinically corrected, most commonly with
spectacles or contact lenses.
This condition is marked by the incapacity to
clearly focus on near objects, is age-related
and comes from the Greek term meaning “old
man’s eye”. It is almost certain
from middle to old age when the focusing capacity
of the eyes reduces. As our eyes age, the protein
in the lens weaken and becomes hard and less
elastic. You may have noticed that many old people
hold whatever they read at a distance. This marks
the onset of presbyopia and holding the book
away reduces the divergence of light and hence
a clearer vision. Soon this fails to work and
then the only way out is convex reading spectacles.
Some other conditions like diabetes, severe
dehydration and overexposure to ultraviolet light
may also damage the lens protein and cause presbyopia.
Prevalence of presbyopia
Although presbyopia is related to the aging
process, its occurrence varies according to certain
geographic factors as well. It is said to occur
earlier in people who live closer to the equator.
Research has also suggested that ambient temperature
rather than latitude causes greater variation
in its prevalence. It is said that more the ambient
temperature, the earlier the chances of presbyopia.
In fact, studies have reported that since the
ambient temperatures are usually high in developing
countries there are fewer cases of presbyopia,
though its occurs at an early age here. Whereas,
in developed Western countries 65% of all people
who wear spectacles suffer from presbyopia.