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I cannot read the newspaper without glasses at night.

I can read it without glasses with one eye but not with the other.



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.

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