Prescriptions may at first seem like just a bunch of numbers and letters, however, as learned in article Have An Eyewear Prescription? Learn To Read It!, there is much more to them than that…especially to the healthcare professional.
When eyewear prescriptions are written, they can then be classified into different areas depending on the power or refractive error.
For instance, if a person is prescribed a -2.50 sph, then the refractive error is called simple myopia, or just myopia because the prescription is written in (-), or minus, for someone who is near sighted, or myopic. The (-) prescription allows the person to see better with distance.
There are seven categories to which prescriptions can fall and they are listed below. It is pretty self explanatory, and will assist any Optician or apprenticing certified Optician fairly well as it is quite easy to memorize and use daily.
IF A PERSON SUFFERS FROM, or the refractive error is:
Simple Hyperopia, the Rx will be (+) sphere
Simple Myopia, the Rx will be (-) sphere
Simple Myopic Astigmatism, the Rx will be plano (-)
Simple Hyperopic Astigmatism, the Rx will be plano (+)
Compound Hyperopic Astigmatism, major meridian power will be (+) (+) on both 90 and 180 degree axis
Compound Myopic Astigmatism, major meridian power will be (-) (-) on both 90 and 180 degree axis
Mixed Astigmatism, major meridian powers will be opposites (-)(+) (+)(-) on both 90 and 180 degree axis
Every single prescription that an optician runs across will fall in one of these sections. Myopic eyes have minus Rx’s and hyperopic eyes have plus Rx’s. Mixed Astigmatism is exactly what it says…both signs, minus and plus are in the prescription.
EXAMPLE 1:
An example of mixed astigmatism would be +3.00 – 4.00 x 90. The power is +3.00 along 90 degrees, and -1.00 along 180 degrees along the major meridians. Therefore, the refractive error is mixed astigmatism. (mixed astigmatism)
EXAMPLE 2:
Another example would be +1.00 -0.50 x 90. Power is +1.00 x 90 and the power is +0.50 x 180 along the major meridians. In this case, it is a compound hyperopic astigmatism. (One must add the sph and cyl power to get the result of +0.50 x 180.)
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An Opthalmologist or Optometrist is where one would need to go for the answer to this question. In general, an astigmatism is based on the shape of your child’s eye in simple terms which causes the light to fall different than it would for someone without astigmatism. Most times, eyewear is used to correct vision for the thousands of people with astigmatism as it is fairly common, however, to speak on a cure, I have never heard of one. That question should be directed to a doctor.
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