Positive angle kappa in albinism

Background Albinism is an inherited disorder of deficient melanin production. There is a high prevalence of strabismus in patients with albinism. We investigated the prevalence of a positive angle kappa in patients with albinism and report its effect on assessment of binocular alignment. Methods We retrospectively reviewed the charts of 207 consecutive patients with the diagnosis of albinism seen at the University of Minnesota between 1984 and 2002. Angle kappa and alignment using prism and alternate-cover test (PACT) and Krimsky measurements were recorded. Results In 99.6% of our patients with albinism, angle kappa was noted to be positive. The mean difference between PACT and Krimsky measurements was 17.11 prism diopters in the more exotropic (or less esotropic) direction per Krimsky test. Because of the high prevalence of a positive angle kappa, esodeviations often appeared less and exodeviations appeared greater than when measured using PACT. Conclusions Positive angle kappa can be considered another clinical feature of albinism. Consideration should be given to the effect of positive angle kappa on alignment as observed by Krimsky measurement when planning extraocular muscle surgery, particularly when preoperative sensory testing suggests binocular potential.