Comparative
Analysis of Visual Function,
Hkarinc Asility and Olfactory Sense
in Usher's Syndrome.
Background: Usher's syndrome is a genotypically and phenotypically heterogeneous
group of diseases with autosomal recessive heredity. Clinically, patients
present with retinitis pigmentosa (RP) and hearing loss, which is moderate
in type II and profound in type I patients. The latter also express vestibular
abnormalities. The following work represents first results &om a joint
effort of the University Eye and ENT Hospitals at Tuebingen in cooperation
with the german RP patient organisation (DRPV) to improve phenotyping.
Following preliminary reports of olfactory deficits, a new threshold test
was used to quantitatively assess the olfactory sense. Methods: 39 patients
with Usher I (8) or II (31) were seen in both the outpatient clinic for
hereditary retinal disorders and the ENT clinic on the same day. The protocol
included history, basic eye exam, Goldmann perimetry, electroretinography
(ISCEV standard), and morphology of anterior and posterior segments. Findings
were entered into a relational data base. Additionally, the results of
an ENT examination, audiometry, and the Erlanger Riechtest ("sniffing sticks")
were recorded. Results: Practically all Usher patients had a progressed
form of RP. Mean visual acuity was 0.52 (type I) and 0.62 (type II), respectively,
and the visual field was ver constricted (median of remaining field 0.0175
and 0.05 steradiant, respectively). The ERG was non-detectable or could
only be obtained using maximal stimulation (response median of the scotopic
10Hz tlicker 0 and 0.87 pV, and of the photopic 30Hz flicker 0.29 and 0.7
pV, respectively). The mean hearing loss (speech audiogram) was 97 and
42%, respectively. The median of the olfactory threshold was, however,
unremarkable (9.7 and 8.5 vs. 8.5 in normals). Discussion: Both groups
showed a progressed RP, however, the differences between type I and II
were not as impressive as in the audiograms. An affection of the olfactory
system could not be found, and there was also no correlation between parameters
resembling visual function, hearing ability, and olfactory sense. This
could be important for the diagnostic differentiation from Refsums syndrome.
Mathias Seeliger 1, Krisna Gendo 1, Eberhart Zrenner 1, Markus Pfister 2, Steffen Paasch 2 und Hans-Peter Zenner 2
1 University Eye Hospital, Dept. II, Schleichstr. 12-16, D-72076 TObingen
2 University Ear, Nose, and Throat Hospital, Silcherstr. 5, D-72076
TUbingen Supported by DFG grants Ru 457/1-2 and Zr 1/7-3)