Eikonometer

Instrument for measuring aniseikonia. The direct comparison eikonometer (or standard eikonometer) uses as a target a cross with a small white disc at the centre of a black square at its intersection. Four pairs of opposing arrows are placed four degrees away from the centre of the cross with the even numbered arrows polarized in one direction and the odd numbered ones in the other direction. The subject wears polarizing lenses so that each set of four arrows is seen by one eye. If the subject has aniseikonia, one set of arrows will not appear aligned with the other. Aniseikonia either in one or more meridians can be measured by means of an adjustable magnifying device before one eye.

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