These prisms are of superior quality. In a recent competitive comparison by the Journal of Pediatric Ophthalmology and Strabismus they noted the following: "It is important to conduct polarized testing through prisms that are known not to interfere with polarization. These prisms appear to cause the least (interfering) effect. Only the right eye's target was seen when the left eye was occluded." Competitive products yielded significantly reduced stereopsis.
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