After completing a minimum of three consistent vision tests you will receive your EyeGlass Numbers (EGN). EyeGlass Numbers are a set of numbers that contain parameters defining refractive error needed for ordering eyeglasses for distance correction. If you take three tests and do not see any EyeGlass Numbers, this indicates one or more tests are inconsistent and more tests are required to produce a set of EyeGlass Numbers. Please continue to take more tests until you have successfully reached three consistent results.
An example of an EyeGlass Number (EGN) record looks like:
|PD:||NV Add +2.00|
The EGNs may seem familiar to you because they are written in the same format as your eye doctor's prescriptions. Note that Cylinders are expressed in negative Cylinder notation.
Spherical & Cylindrical values are measured in Diopters and represent components of your refraction correction.
Axis represents the angle the Cylindrical component makes with respect to an imaginary horizontal line through your eye.
PD corresponds to the Pupillary Distance in millimeters (mm). This is the distance between your two eyes.
NV ADD is called the near vision add and is needed for persons with Presbyopia (reading vision). This number is not measured, instead it’s an estimate based on your age.