Contact Lens Basics

Anisometropia And Contact Lenses


Undoubtedly, contact lenses are used to correct your eye vision by correcting various eye disorders like astigmatism, anisometropia, myopia, and alike. Along with correcting vision, they also provide a natural look which is absent in the case of spectacles. People wearing contact lenses or spectacles have some degree of anisometropia.

This is a condition in which there is a difference of refractive errors between the two eyes. Mostly this term is used when the difference reaches 2.00 diopters and more. There is also another form of anisometropia called anitmetropia in which there is a difference in the power designations between the eyes like your right eye may have plus power while the left eye may have a minus one.

When spectacles are used to correct the refractive error, the problems begin to erupt. Images are displaced by all corrective lenses. Converging or magnifying lens displace the images towards the edges of the lens creating magnification whereas diverging or minifying lens displaced the images towards the center of the lens creating minification.

Displacement depends upon the power of the lens. In an anisometropia patient, there is a great difference of displacement between the eyes. Displacement increases as the wearer moves away from the center of the lens, sometimes resulting in double vision. So, people with anisometropia and distance vision have to tilt their head to view through the center of the lens.

This prism imbalance can be corrected by applying a technique while making spectacles called bicentric grinding. In this, either your eye with most minus power or least plus power has prism grown only in half of the lens therefore creating a visible line bisecting the lens. The wearer also has option of wearing two set of glasses separately for reading and distance. But, to avoid this condition, most wearers prefer to wear contact lenses as they help in reducing the prismatic effect experienced with spectacle wear.

It is really difficult to know the exact cause of anisometropia as it could be due to congenital or could be a result of trauma. In fact, if one of your eye has remarkable refractive error than the other eye, it becomes more dominant resulting in loss of vision of the non dominant eye. The severity of the condition can also lead to other conditions like amblyopia and strabismus.