What Is Anisometropia And Antimetropia?

Anisometropia is when the vision of the eyes differs by a large margin. For instance, if a person has the refractive power of -2.50 in the right eye and for the left eye, the refractive power is +1.75. There is a difference of over 3 diopters between both eyes, therefore, this case would be anisometropia.

Now, don’t confuse this with antimetropia, however, as this term only refers to prescriptions that differ in sign such as OD -0.25 OS +0.50. As can be seen here, there is a negative sign for the right eye and a positive sign for the left eye. This situation is all that is needed for antimetropia.

Anisometropia does not have to be a difference in sign(though it can be), but it does have to be a large difference in power between both eyes. That being said, this can cause issues when a patient is having to select frames as the difference in prescription is so much that it more than likely will cause an imbalance in how the lenses fit inside the frame. Several things may need to be altered such as base curves, nose pads, ruling out certain types of frames such as semi-rimless or rimless frames etc. Because of this, the optician needs to be prepared to help the patient select the frame that not only will compliment but also deliver great fit and wear when it comes to this special type of prescription.