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Lori Ann F. Kehler, Lisa A. Fraine, Pengcheng Lu; Computer-Based Aniseikonia Testing in Children with the Aniseikonia Inspector, Version 3. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3885.
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Aniseikonia occurs when there is inequality in image size between eyes. Aniseikonia in children is most often associated with anisometropia and has been associated with an increase in amblyopia and strabismus. If aniseikonia is a factor in amblyogenesis and/or poses a limit on treatment outcomes, a readily-available clinical test would be useful. The gold-standard aniseikonia test is the Space Eikonometer (American Optical Corp. Southbridge, MA), however it is no longer in production. Several computer-based programs have been released and tested, including the Aniseikonia Inspector (Optical Diagnostics, Culemborg, The Netherlands.) Versions 1.0 and 2.0 have been tested with varied results. Aniseikonia Inspector Version 3.0 (AI3) may present an advantage in children, because it employs a forced-choice method and has an extensive calibration for horizontal heterophoria. The present study is designed to evaluate induced aniseikonia in children ages 5 to 13 using AI3.
All subjects were present for a standard-of-care eye examination and had at least 20/40 best-corrected visual acuity and no history of strabismus or amblyopia. Subjects were seated 37 cm in front of a computer monitor with the room lights dimmed. Red/green anaglyph glasses were placed on the patient for heterophoria calibration. All trials of the AI3 were performed in the vertical direction only, using the short (12 point) test. Before actual testing, the patient was instructed to identify the larger target and press the corresponding arrow key without wearing the red/green anaglyphs. The red/green anaglyphs were then placed on the patient, and two trials were recorded. Each subject was then randomized to have a 4% size lens added to either the right eye or the left eye. Two trials were performed in this manner, and then two more trials were performed with the size lens over the alternate eye.
18 children were enrolled; 3 subjects were not able to complete testing due to lack of attention or understanding (ages 5, 6, 10). Results from each condition (background aniseikonia, induced aniseikonia OD, induced aniseikonia OS) were averaged for each patient. With the 4% size lens over the OD, mean aniseikonia measured -3.6%, SD 1.2 (expected mean -3.85%). With the 4% size lens over the OS, mean aniseikonia measured 3.59%, SD 2.0 (expected mean 4%.)
Most children were able to complete aniseikonia testing with AI3, and induced aniseikonia measurements were close to expected values using a 4% size lens. However, the considerable standard deviation indicates variability, possibly due the child’s ability to adapt to the size lens or the inherent inattention of the young subject.
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