Positive angle kappa: a possible sign of aniridia

Aniridia is a panocular disorder with variable expressivity, caused by PAX6 mutations. Foveal hypoplasia and nystagmus occur in both aniridia and albinism. Individuals with albinism have a moderately positive angle kappa. This study evaluates the angle kappa in individuals with aniridia.

We performed a retrospective chart review of recorded angle kappa for individuals with aniridia. In addition, we prospectively examined the monocular corneal light reflex in each eye of patients with congenital aniridia and central fixation. We recorded other ocular characteristics and the results of gene testing. Patients with eccentric fixation or corneal surgery were excluded, as were patients with retinal abnormalities that might have influenced the angle kappa.

We included sixteen individuals with congenital aniridia and found that all had a positive angle kappa. Two patients underwent pattern visual evoked potential (VEP) testing with monocular stimulation and were found to have a reversal of polarity, indicating misrouting of the retino-striate fibers.

The phenotype of aniridia is variable. However, a positive angle kappa may be considered to be a frequent clinical feature of aniridia.