The data is expressed in dioptres.
This is one of the vision tests carried out in the office by your ophthalmologist, who will explain it to you as a measure of visual acuity from 0 to 10 out of 10 (sometimes more in some patients after laser surgery).
- the first value is the spherical power of the lens. A ‘+’ sign means you are hypermetropic (eye too short or cornea too flat) and a ‘-’ sign means you are myopic (eye too long or cornea too arched), or ‘plane’ there is no correction.
- The second value is indicated in parentheses. It represents the cylindrical power of the lens, which corresponds to astigmatism (an oval cornea with a flat side on one axis and more curved on the opposite axis of 90°). There is not always a correction. Sometimes expressed in negative (most often by doctors) or in positive (most often by opticians), it makes no difference.
- The third value is only present to complete the second. It represents the axis of rotation relative to the horizontal, expressed in degrees, and allows for the proper correction of your astigmatism.