Answer:
Dear
Anthony,
Having
a regular eye examination promotes eye health.
The most
common age-related vision change -presbyopia - happens to almost everyone
beginning between the ages of 40 and 50.
Presbyopia
is a symptom caused by the natural course of aging.
The first
symptoms most people notice are difficulty reading fine print, particularly
in low light conditions.
Presbyopia
sometimes affects your left eye and your right eye differently.
The optical
power of the human eye is about 40 diopters. The eye of a normal young
person can adjust an additional 20 diopters. By age 25 this accommodation
is usually reduced to about 10 diopters and by age 50 to a mere 1
diopter. It is this diminishing capacity for adjustment, called presbyopia
that warrants reading glasses.
Presbyopia
sometimes affects your left eye and your right eye differently. Therefore,
you may need, for example, a +1.50 in your right eye and a +1.75 in
your left eye. This is normal, although many people can overcome their
Presbyopia perfectly by using glasses that have the same diopter strength
in each eye. Nevertheless, if you fall in the category of people who
need differing lens strengths for each eye, you could be doing yourself
a grave dis-service if you bought a cheap pair of one-size-fits-all
drug store glasses that had the same diopter strength in both lenses.
The easiest
way to correct presbyopia is to choose from a selection of glasses
of different strengths.
Measure
the nearest point of clear vision with the glasses that you think
are correct. Do this by holding the book too close so it is blurred,
and then slowly moving it away until you report it is totally clear.
Measure the distance of this nearest clear point from the eye with
a tape measure or piece of string.
Change the strength of the lenses until the nearest point is about
28-30cm from eye to book, and you are reading comfortably.
Choosing
reading glasses that are too weak will result in continued symptoms,
while glasses that are too strong often result in needing to hold
the reading material too closely.
Drugstore
reading glasses are best for people with reasonably good uncorrected
distance vision.
