The Effect of Wearing Prism in Infantile Nystagmus

ABSTRACT

In infantile nystagmus, we evaluated the changes in visual acuity, nystagmus intensity and face turning between with prism and without prism. 4 patients chosen in our study had a fusional ability examined by Worth-4Dot test and were not accompanied with strabismus. It was confirmed by the inspection of eyes and electro-oculogram that visual acuity at near fixation was better than that at distant fixation and the nystagmus intensity was decreased by convergence. The age distribution of the patients was between 6 and 20 years old. The period of wearing prism ranged from 2.5 to 8.5 months. Improvement in binocular visual acuity at distant fixation with prism was noted relatively from 4 lines to 1 line, the nystagmus intensity (Amplitude x Frequency) calculated by analyzing eletro-oculogram records resulted in the decrease with prism in comparison with that without prism (p<0.05). And the main cause of decrease in nystagmus intensity was determined by that in amplitude rather than frequency. The ranges of correction of face turning at distant fixation wer between 10 degrees and 20 degrees. As the result of this study, in case that nystagmus intensity can be decreaed by convergence and prism is worn succeedingly without any trouble, we assume that the use of bilateral base-out prism will be one of the effective methods for decrease in nystagmus intensity, improvement in visual acuity and face turning.