Abstract
PURPOSE: The cilium in photoreceptors appears ultrastructurally very similar to the nasal ciliated epithelium. The purpose of this study was to evaluate the nasal ciliary beat frequency and beat pattern in patients with retinitis pigmentosa (RP) and Usher syndrome type II and compare it with that of healthy control subjects. METHODS: A prospective, comparative control study. Fresh samples of nasal mucosa were obtained from 13 patients with typical forms of RP, and from 4 patients with Usher syndrome type II. The nasal ciliary beat frequency (CBF) and beat pattern were determined using high-resolution digital high-speed video imaging (DHSV). The control group included 32 fresh nasal mucosa samples from 32 healthy volunteers without any other confounding diseases. RESULTS: The nasal CBF was lower in patients with Usher syndrome than in control subjects (Mann-Whitney U test, P = 0.01). The nasal CBF was 9.28 ± 0.4 (mean ± SD) Hz in patients with Usher syndrome and 10.82 ± 1.39 Hz in patients of the control group. No significant difference was observed in the nasal CBF between the RP (10.59 ± 1.54 Hz) and control group (Mann-Whitney U test, P = 0.64). Normal ciliary beat pattern was observed in all the patients and healthy volunteers. CONCLUSIONS: The nasal CBF is diminished in patients with Usher syndrome type II, whereas it remains normal in simplex RP patients. These results add evidence to the fact that Usher syndrome could be a primary ciliary disorder.