|Classification and external resources|
Aniseikonia is a condition that results from an excessive difference in the prescription between the eyes. This causes a difference in image size perceived between the eyes from unequal magnification, and 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 is with contact lenses, or magnification size-matched lenses (isokonic lenses).
- American Academy of Ophthalmology. Core Ophthalmic Knowledge: Aniseikonia Practicing Ophthalmologists Learning System, 2017 - 2019 San Francisco: American Academy of Ophthalmology, 2017.
- Gerstenblith, Adam T., and Michael P. Rabinowitz. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2012. Print.
- Trattler, Bill, Peter K. Kaiser, and Neil J. Friedman. "Chapter 1: Optics." Review of Ophthalmology. Edinburgh: Saunders Elsevier, 2012. Print.
- Ugarte M, Williamson TH. Aniseikonia associated with epiretinal membranes. Br J Ophthalmol. 2005; 89:1576-80