Difference between revisions of Correction
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An [[optometrist]] will test your vision and determine the amount of refractive error in your eyes. The full prescription should correct your vision so that there is no [[blur]] at 20 feet. | A full prescription is a conventional glasses prescription. An [[optometrist]] will test your vision and determine the amount of refractive error in your eyes, and write a prescription as close as possible to that. The full prescription should correct your vision so that there is no [[blur]] at 20 feet. | ||
A prescription may look like this: | A prescription may look like this: | ||
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OD is oculus dextrus, or Latin for right eye. | OD is oculus dextrus, or Latin for right eye. | ||
OD is oculus sinister, or Latin for left eye. | OD is oculus sinister, or Latin for left eye. | ||
= Rounding = | |||
You will note that most prescriptions will round to the nearest quarter diopter. This is the level of precision available in standard pre-ground lenses, which make glasses cheaper and faster to make than custom ground lenses. You may have a more precise prescription if it is written for specific lens grinding systems, or a less precise prescription it is written for contacts. | |||
= Contacts Vs Glasses = | |||
Your prescription is specifically written for either contacts or glasses. [[Vertex Distance]] plays a role in effective lens strength, so the contacts which sit closer to your eye may be written as a weaker prescription than glasses. Vertex Distance is hard to measure, and contacts may act differently as the eye adapts to them, so if you have a strong lens your optometrist may need to do additional refraction tests with the contacts in and adjust your prescription slightly. | |||
See also: | See also: | ||
* [[Normalized]] | * [[Normalized]] | ||
* [[Differentials]] | * [[Differentials]] |