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Mathias W. Seeliger, Eberhart Zrenner, Eckart Apfelstedt-Sylla, Gesine B. Jaissle; Identification of Usher Syndrome Subtypes by ERG Implicit Time. Invest. Ophthalmol. Vis. Sci. 2001;42(12):3066-3071. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
purpose. Usher syndrome (US) is a recessively inherited disorder combining
retinitis pigmentosa (RP) and a sensorineural hearing loss. The
classification in subtypes is based mainly on auditory tests. The
purpose of this study was to analyze implicit time (IT) differences in
the electroretinogram (ERG) between RP alone, US I, and US II.
methods. The data of 15 control subjects and of 15 patients with US I, 15 with
US II, and 15 with RP with nonzero 33-Hz flicker ERG responses were
analyzed. The ITs of three signal peaks (P1–P3) were evaluated.
Sensitivity and specificity of a test to distinguish between US I and
II based on timing differences were determined. Multifocal (mf)ERGs
were used to assess differences in disease topography.
results. Despite the similar amplitude loss with retinal eccentricity in the
mfERG in all three groups, the peak delay in US I was negligible
compared with that in US II and RP. In the flicker ERG data, US I and
control subjects had almost identical peak times, and the same was true
for subjects with US II and RP. Because of the slight overlap between
US I and II, the diagnostic test achieved a sensitivity of 100% and a
specificity of 93.3%.
conclusions. Substantial timing differences between US I and II and their usefulness
for a diagnostic test were demonstrated. This finding may also be the
basis for further investigations regarding the structural differences
of retinal impairment between US I and II on a cellular
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