Anisometropia

Are there differences between the right and the left eye in the nature or extent of certain optical refractive errors ( ametropia ), one speaks of an anisometropia. The differences can be very diverse. So it is possible, for example, that one eye is nearsighted and the other farsighted. It also happens that one eye is very small far-sighted, while the other has a very strong farsightedness. For myopia and astigmatism this may also apply. The extent of these refractive errors is given in units of diopters. A anisometropia to an extent of 0.5 diopters is still in the normal range, in addition, it is considered as morbid.

Causes

A distinction is made between the Brechwertanisometropie and Längenanisometropie. Refractive index differences of the cornea and lens of the eye are the cause of the Brechwertanisometropie and thus the refractive error. The Längenanisometropie in turn arises from the different lengths of the two eyeballs (myopia and hyperopia).

Correction and treatment

Resulting from the correction of anisometropia using lenses - more than with the use of contact lenses - retinal images of different size ( aniseikonia ). From a refractive index difference of three diopters in part massive disturbances of binocular vision can thereby occur. The spectacle corrections that may be necessary due to the greatly differing indices of refraction of the eyes, also lead to a cosmetically striking appearance of the eye area and because of the different weight to a one-sided pressure load. In addition, prismatic side effects may occur, the function of the current through the focus of the glasses cause a variable degree of heterophoria ( anisophoria ).

Beyond a certain degree of anisometropia to lenses therefore offer no more than appropriate corrections to, but should be replaced by contact lenses or refractive surgery for example, this allows the organic, anatomical and functional situation.

Refraktionsamblyopie

In childhood, at a time in which the vision is still developing, anisometropia can from a certain extent to a functional amblyopia, a so-called Refraktionsamblyopie (synonym: amblyopia ex anisometropia ) lead to the higher defective eye. A correct treatment in such cases requires an appropriate lens prescription, which must be generally supported by a consistent occlusion treatment. Untreated or inadequately treated Refraktionsamblyopien can no longer be successfully treated in puberty usually from the entrance.

Monovision

A specific form of congenital or an eyeglass or contact lens correction or surgery (eg, cataract surgery ) induced anisometropia allows one eye, objects near, and see the other, those in the distance in each case without glasses sharp to be able to. This phenomenon is independent of accommodation and thus given to old age and is also known as monovision. This condition not a complete stereoscopic vision is often possible and thus might regarded as undesirable.

The congenital form of anisometropia was, for example, also occurs in Johann Wolfgang von Goethe (and Konrad Adenauer ) and is therefore also known as Goetheblick.