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.
The basic finger test of the subjective level of the Fly's wings gives a quite reasonable approximation of local stereoscopic depth perception. In terms of practical investigation the finger test shows in convincing manner whether the individual stereoscopic ability is based on normal, subnormal or anomalous binocular interaction.
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.
The multifocal ERG using the m-sequence stimulation technique allows the derivation of 61 - 241 local ERG signals in a central visual field of about 60 degree diameter in a short time between 4 and 16 min. A recording in a light adapted state offers local information comparable to cone responses in the full-field ERG. Retinal functional losses due to regional disorders in outer retinal layers can be described in detail with this technique. In maculopathies decreased or absent central ERGs are found surrounded by normal ERG. The extent of the central lesion can be estimated. In diseases of the outer retina the pattern of distribution of multifocal ERG activity is similar to the the pattern of the visual field defect. In addition to decreased ERG amplitudes a delay of implicit time may be an important sign of pathology, i.e. the pronounced delay of implicit times in the periphery in retinitis pigmentosa and the implicit time delays in regions associated with retinal edema like CRVO and cystoid macula edema in intermediate uveitis. No simple correlation of the first order kernel multifocal ERG and field defects could be found in disorders of the ganglion cell layer. The multifocal ERG is therefore useful in the differential diagnosis of retinal and optic nerve diseases.
Microsurgical decompression of the soft tissue via an approach from behind the globe proved to be a very gentle alternative to conventional methods of orbital decompression because of the satisfying functional and esthetic rehabilitation in selected cases.
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