Aniseikonia is the difference in image size perceived between the eyes from unequal magnification due to either anisometropia or retinal pathology. This can manifest with symptoms of headache, dizziness, disorientation, and excessive eye strain.
When the magnification variance between the two eyes is disproportionately high, symptoms can arise. Symptoms include headache, eye strain, disorientation, and dizziness.
Aniseikonia can occur naturally or secondary to correction of a refractive error. Up to 7% of aniseikonia between the eyes is usually tolerated, and corresponds to approximately 3 diopters of anisometropia.
Types of Aniseikonia:
- Optically-induced aniseikonia: this condition occurs secondary to anisometropia caused naturally, or secondary to refractive surgery, pseudophakic IOL implantation, or aphakia.
- Retinally-induced aniseikonia: compression, stretching, or damage to the retina can cause light projected on the retina by a perceived image to appear larger (macropsia) or smaller (micropsia), as a variable number of photoreceptors may be stimulated. Causes of retinally-induced aniseikonia include retinal detachment, retinal tears, retinoschisis, macular edema, macular hole, or epiretinal membranes.
Treatment varies based on the cause of aniseikonia. When it is due to anisometropia, treatment is with contact lenses, corneal refractive surgery, or lens-based refractive surgery. When due to retinal pathology, magnification size-matched lenses known as isokonic lenses can be used.
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