A mutation in Myo15 leads to Usher-like symptoms in LEW/Ztm-ci2 rats.

The LEW/Ztm-ci2 rat is an animal model for syndromal deafness that arose from a spontaneous mutation. Homozygous animals show locomotor abnormalities like lateralized circling behavior. Additionally, an impaired vision can be observed in some animals through behavioral studies. Syndromal deafness as well as retinal degeneration are features of the Usher syndrome in humans. In the present study, the mutation was identified as a base substitution (T->C) in exon 56 of Myo15, leading to an amino acid exchange from leucine (Leu) to proline (Pro) within the carboxy-terminal MyTH4 domain in the proteins' tail region. Myo15 mRNA was expressed in the retina as demonstrated for the first time with the help of in-situ hybridization and PCR. To characterize the visual phenotype, rats were examined by scotopic and photopic electroretinography and, additionally, histological analyses of the retinas were conducted. The complete loss of sight was detected along with a severe degeneration of photoreceptor cells. Interestingly, the manifestation of the disease does not solely depend on the mutation, but also on environmental factors. Since the LEW/Ztm-ci2 rat features the entire range of symptoms of the human Usher syndrome we think that this strain is an appropriate model for this disease. Our findings display that mutations in binding domains of myosin XV do not only cause non-syndromic hearing loss but can also lead to syndromic disorders including retinal dysfunction.

"Minimized rotational vestibular testing" as a screening procedure detecting vestibular areflexy in deaf children: screening cochlear implant candidates for Usher syndrome type I.

Morbus Usher (USH), a combination of sensorineural hearing loss and retinal visual impairment, is classified into group I-III. USH I patients are born deaf. Within the first 10 years of life, they develop a severe vision impairment due to progressive retinal dystrophy (retinitis pigmentosa). USH I patients show vestibular deficits. The incidence of USH I among congenitally deaf children is assumed to be as high as 10%. We intend to create a simple examination procedure for screening congenitally deaf children for vestibular deficiency and subsequently USH I. The examination procedure is named "Minimized Rotation". The vestibular function of deaf children was examined by Minimized Rotation during their preoperative cochlear implant candidacy examination. A lack of postrotational nystagmus was seen as an indication for vestibular deficit. Subsequently some of these patients were examined under general anaesthesia by electroretinography (ERG) at the Department of Ophthalmology. A total of 117 children were examined by Minimized Rotation. In 19 children (16.2%) no rotational nystagmus was found. Six of these children were additionally examined at the Department of Ophthalmology using Ganzfeld ERG. Three of them (50%) showed generalized dysfunction of the retina; 8.1% of the children undergoing preoperative evaluation for cochlear implatation are assumed to show abnormalities of the retina. Rotational examination seems to be an appropriate screening method to detect vestibular deficits, which is one sign of USH I. The results always have to be verified by Ganzfeld-ERG or further genetic investigations. Children with USH I are threatened by progressive reduction of vision. We, therefore, consider USH I children always to be implanted bilaterally with a cochlear implant to maximize the benefit of auditory rehabilitation.

Comparison of intraocular pressure measurements with the digital tonometer TGDc-01 'PRA' and the Goldmann applanation tonometer.

BACKGROUND: To compare intraocular pressure (IOP) measurements obtained with the digital tonometer TGDc-01 'PRA' with those from a Goldmann applanation tonometer (GAT). METHODS: The IOP in 176 eyes of 88 healthy volunteers was measured prospectively in a sitting position. One single measurement, generated by the TGDc-01 PRA, was compared with a single reading from the GAT. RESULTS: Mean IOP values were 13.0 +/- 3.7 mm Hg for the TGDc-01 PRA (range, 4-22 mm Hg) and 14.9 +/- 3.2 mm Hg for the GAT (range, 8-27 mm Hg). The mean difference was 1.9 mm Hg with a standard deviation of 2.77 mm Hg, and this was statistically significant (p < 0.001, paired t test). CONCLUSIONS: In comparison to the GAT, the TGDc-01 PRA underestimated IOP on an average of 1.9 mm Hg. Only 50.6% of all measurements were within the +/-2 mm Hg difference range. Thus, the TGDc-01 PRA has no high coincidence degree with the GAT. Both methods were not equivalent.

[Positive influence of color experience on result of color-arrangement-test Roth 28-hue (E) desaturated - a clinical study on 44 patients]. / Positiver Einfluss von Farberfahrung auf das Ergebnis von Farbsinnprüfungen mit dem Farbpigmentprobentest Roth 28-hue (E) desaturiert - Klinische Studie an 44 Probanden.

BACKGROUND: The color arrangement test can be applied for early diagnosis of diabetic retinopathy, even small confusion of colors influence clinical diagnosis. It is therefore necessary to be aware of influential factors. METHODS: Forty-four patients with color-experience (VW-Werk Wolfsburg) were included and devided in two groups: group 1: non-smokers without ophthalmological and systemic diseases (n = 27, 42+/-9 years), group 2: smokers without ophthalmological and systemic diseases (n = 17; 43+/-8 years). The control group 3 (n = 30; 42+/-4 years) included non-smokers and the control group 4 (n = 10; 42+/-8 years) smokers, both groups without color-experience, ophthalmological and systemic diseases. Besides the ophthalmological examinations (visual acuity, refraction, intraocular pressure, slit lamp and fundus examination) the color-vision was tested by the color-arrangement-test Roth 28-hue (E) desaturated monocularly under standard conditions: The background used was black cardboard, illuminated by two Osram fluorescent lamps (L36W/12LDL Daylight) providing 2000 lux at the test table. RESULTS: Ophthalmological examination in all subjects was without pathological findings. The mean error score in the non-smokers with color-experience (median+/-mean absolute deviation: 48+/-47) was lower than in the non-smokers without color experience (72+/-45; Mann-Withney-U-Test: p = 0.02). The mean error score in the smokers with color-experience (60+/-60) was lower than in the smokers without color-experience (156+/-65; p = 0.0014). No statistically significant difference was found between the measurements of the right and left eye (Wilcoxon-Test: group 1: p = 0.89; group 2: p = 0.9; group 3: p = 0.77; group 4: p = 0.87). CONCLUSION: Color experience improves the results in color-arrangement-tests like the Roth 28-hue (E) desaturated and should be considered in quantitative evaluation.