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Biomedical subjects

K Rüther

Publications and source records attributed to K Rüther.

At least 19 recordsLinked to original sources
PubMed2004

[Clinical and genetic findings in a patient with fundus albipunctatus].

METHODS: The 38-year-old index patient was examined by visual acuity testing, perimetry, dark adaptometry, funduscopy, electroretinogram (ERG), and multifocal ERG. She was screened for mutations in exons 2-5 and exon/intron boundaries of the 11- cis retinol dehydrogenase gene by direct sequencing. RESULTS: Visual acuity was 1.0, but perimetry revealed paracentral scotomas associated with reading problems. The optic discs were normal. After 45 min of darkness there was nearly no increase of light sensitivity. After 30 min of dark adaptation, the scotopic ERG showed reduced amplitudes, but after 60 min a nearly normal level was reached. The 30-Hz flicker response of the cone ERG showed borderline implicit times, but no reduction of amplitudes. However, multifocal ERG clearly disclosed a paracentral amplitude reduction as the reason for the visual field defects. The fundus was typical for fundus albipunctatus. The patient is a compound heterozygote carrying a Ile33Asn and a Arg157Trp mutation. CONCLUSIONS: The paracentral visual field defects were due to cone dysfunction. So far the patient exhibits no cone dystrophy.

Adult↗
PubMed2003

[Testing central retinal function with multifocal electroretinography before and after photodynamic therapy].

BACKGROUND: Photodynamic therapy (PDT) is applied for certain forms of choroidal neovascular membrane (CNV). The aim of this study was to investigate the effect of PDT on central retinal function as assessed by multifocal electroretinography (ERG). METHODS: 24 patients (25 eyes) with CNV (>50% classic 12 eyes) or occult (9 eyes) in age related macular degeneration (AMD) and CNV with pathological myopia (4 eyes) were treated by PDT using Verteporfin((R)). Before and a median of 6 weeks after therapy, central retinal function was examined using multifocal ERG (RetiScan, 61 hexagons, first-order response). RESULTS: In the area of treatment,we found a tendency of the amplitude of the first positive deflection (P1) to decrease and of the implicit time to increase, but both effects were not statistically significant. These alterations were more pronounced in eyes with occult CNV and in myopia-related CNV. Amplitude reduction and implicit time prolongation could also be found in the areas represented by the multifocal ERG but not treated. There was no significant correlation between change in visual acuity after PDT and amplitude of the multifocal ERG. CONCLUSION: The effects of PDT on retinal function seem to be moderate as assessed by multifocal ERG. An inherent problem of this investigation was the recruitment of nontreated patients as controls. Future goals are investigations of patients with repeated PDT and of long-term alterations in multifocal ERG after PDT.

Adult↗
PubMed2002

Is visual field constriction in epilepsy patients treated with vigabatrin reversible?

OBJECTIVE: To evaluate the reversibility of vigabatrin associated visual field constriction. BACKGROUND: Visual field constriction (VFC) occurs in approximately 40 % of epilepsy patients under treatment with vigabatrin (VGB). There is still controversy about whether VGB-associated VFC is reversible. From a cross-sectional study there is evidence that VFC does not reverse three to six months after stopping VGB treatment. So far, there are no long term studies on this subject. METHODS: We performed a follow-up study on 15 epilepsy patients (eight women, seven men, median age 45 (21-58) years) with VGB-associated VFC but otherwise normal ophthalmological examination. Kinetic and static perimetry was performed one and two years after VFC was diagnosed (baseline examination). Visual field size at first and at second year-follow-up was compared with the baseline examination. Because discontinuation of VGB-treatment was dependant on clinical needs, patients either stopped VGB treatment before or after VFC was diagnosed. In a small group of patients VGB treatment was continued despite of VFC. RESULTS: There was no statistically significant difference in visual field size comparing baseline values with first year and second year follow-up examinations either in patients who stopped VGB treatment (n = 11) or in patients who continued VGB treatment on a reduced dosage (n = 4). CONCLUSION: Although our data are based on a relatively small group of patients there is evidence that VFC resulting from VGB treatment is not reversible in epilepsy patients after stopping the drug.

Adult↗
PubMed2002

Visual field constriction in epilepsy patients treated with vigabatrin and other antiepileptic drugs: a prospective study.

BACKGROUND: Visual field constriction (VFC) has been described in about 30 % to 50 % of patients treated with the antiepileptic drug (AED) Vigabatrin (GVG). The exact incidence of VFC related to GVG exposure is unknown. Risk factors other than medication have not been identified as yet, and it is unclear whether the occurrence of VFC is restricted to the use of GVG. METHODS: In a longitudinal study, we investigated 60 epilepsy patients who received GVG and other AEDs. Patients underwent full ophthalmological examination including perimetry. RESULTS: 16 of 60 patients exposed to different AEDs developed VFC, which was judged as clinically relevant by an experienced neuroophthalmologist. VFC was observed significantly more often in patients treated with GVG as add-on- or monotherapy as compared with patients who had never been exposed to GVG (13/29 versus 3/31). Within the subgroup of 23 patients who received GVG as add-on therapy, those who developed VFC had been exposed to GVG for significantly longer than patients without VFC. The only non-treatment related feature associated with VFC was older age. Type and severity of epilepsy or type and number of concomitant AED were not related to the occurrence of VFC. CONCLUSIONS: The findings of an overrepresentation of VFC in patients receiving GVG and of a correlation between duration of GVG treatment and occurrence of VFC support the causal role of GVG treatment in the development of VFC. Old age is a possible risk factor for the development of VFC associated with GVG in epilepsy patients.

Adult↗
PubMed2001

Mutant rhodopsin transgene expression on a null background.

PURPOSE: To study mechanisms leading to photoreceptor degeneration in mouse models for autosomal dominant retinitis pigmentosa (adRP) based on the rhodopsin P23H mutation. METHODS: Mice of a transgenic line expressing a rhodopsin triple mutant, V20G, P23H, and P27L (GHL), were mated with rhodopsin (rho) knockout mice. Littermates of various ages and genotypes (GHL+rho+/+, GHL+rho+/-, and GHL+rho-/-) were examined for outer nuclear layer thickness and outer segment formation (histology), fate of mutant rhodopsin (immunocytochemistry), and photoreceptor function (electroretinogram; ERG). RESULTS: Mice expressing GHL-rhodopsin in the absence of wild-type rhodopsin had severe retinopathy, which was nearly complete by postnatal day (P)30. GHL-rhodopsin formed homodimers nearly exclusively on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, whereas wild-type rhodopsin predominantly formed monomers. Expression level of mutant rhodopsin in predegenerate (P10) GHL+rho-/- retinas was low, approximately 10% to 25% of normal levels. No elaboration of disc membrane or outer segment formation was observed at any time point examined. The mutant rhodopsin was found mostly in perinuclear locales (endoplasmic reticulum; ER) as evidenced by colocalization using the antibodies Rho1D4 and calnexin-NT. CONCLUSIONS: GHL-rhodopsin dimerizes, localizes to the ER, and fails to transport and support outer segment formation. Additionally, the mutant protein does not support a scotopic ERG a-wave and accelerates photoreceptor degeneration over that occurring with the rhodopsin knockout alone. These findings indicate a cytotoxic effect of the mutant protein, probably elicited by an unfolded protein response.

Animals↗
PubMed1999

Recurrent NF1 gene mutation in a patient with oligosymptomatic neurofibromatosis type 1 (NF1).

We report a 21-year-old male with symptomatic optic glioma who does not fulfill the diagnosis of neurofibromatosis 1 (NF1) according to standard NIH criteria. Analysis of the NF1 gene revealed a recurrent mutation in exon 37 (C6792A or Y2264X). This nonsense mutation causes skipping of exon 37 during the splicing process and is predicted to result in a protein shortened by 34 amino acid residues. The mutation was detected in all tissues examined (blood lymphocytes, oral mucosa, and dermal fibroblasts). The same mutation was previously found in 3 patients with clinically confirmed NF1. To our knowledge, this is the first report of an adult patient carrying a putative (non-mosaic) NF1 gene mutation in multiple tissues but not fulfilling the NIH criteria for the clinical diagnosis of NF1.

Adult↗
PubMed1999

Familial macular cone dystrophy: diagnostic value of multifocal ERG and two-color threshold perimetry.

BACKGROUND: It is difficult to detect receptor dysfunction in patients with marked bilateral visual loss but only mild morphological alterations of the fundus. METHODS: Two patients, father and son, with visual acuity loss to 20/100 were examined. Using the multifocal ERG, 61 local cone ERGs from each eye were derived from the central visual field. The dark-adapted two-color threshold perimetry using stimuli of 500 nm and 656 nm for rod and cone function was investigated along the horizontal meridian of the visual field. RESULTS: In the multifocal ERG of both patients a macular response was absent. From eccentricity at and anterior to 5 degrees, good multifocal cone activity was recorded. Cone thresholds were markedly diminished in the macula. The rod thresholds were borderline in the father and normal in the son. CONCLUSIONS: Multifocal ERG is a novel technique, very well suited to reveal the topography of cone function. Using two-color threshold perimetry affords an opportunity to differentiate between rod and cone functional defects. Both together helped to establish the diagnosis of macular cone dystrophy in the present family.

Adult↗
PubMed1999

Clinical and electrophysiologic results after intracameral lidocaine 1% anesthesia: a prospective randomized study.

OBJECTIVE: To evaluate the efficacy and safety of intracameral lidocaine in cataract surgery compared to peribulbar anesthesia. DESIGN: A prospective, randomized, controlled study. PARTICIPANTS: A total of 200 consecutive cataract patients (200 eyes) participated. INTERVENTION: Eyes were randomly assigned to two groups: one group received 0.15 ml intracameral 1% unpreserved lidocaine combined with topical anesthesia (oxybuprocaine); the other group received 6 ml prilocaine peribulbar before phacoemulsification with sclerocorneal tunnel incision. MAIN OUTCOME MEASURES: Duration of surgery was measured; implicit time and amplitudes of the b-waves of the photopic electroretinogram (ERG) potentials (single-flash ERG and the 30-Hz flicker ERG) were recorded; frequencies of intraoperative problems, complications, intraoperative, and postoperative pain were evaluated. RESULTS: After lidocaine anesthesia combined with topical anesthesia, similar complications were found, longer operation time (P < 0.001), and significantly better visual acuity immediately after surgery (P < 0.001). The ERG amplitudes were not significantly reduced after 0.15-ml intracameral lidocaine half an hour after surgery (P > 0.05). CONCLUSION: Intracameral lidocaine 1% combined with topical anesthesia can be recommended as an alternative procedure to peribulbar anesthesia in cataract surgery with corneoscleral tunnel incision.

Aged↗
PubMed1999

[Clinical significance of objective vision assessment using visually evoked cortical potentials induced by rapid pattern sequences of different spatial frequency].

BACKGROUND: In patients where reliable subjective assessment of visual acuity is impossible, further diagnostics should be enhanced by an objective method. PATIENTS AND METHODS: A group of 34 patients was examined by objective assessment of visual acuity using visual evoked potentials (VEP) as described by Hajek and Zrenner in 1988. The presentation of five checkerboards with different spatial frequency in repetitive sequences on a TV-monitor elicits a series of transient visual evoked potentials. Shape and amplitude of each wavelet depends on check size and directly reflect a spatial tuning function with a low- and high-frequency cut-off. This amplitude is described by a polynomial fit (2nd order). The function's intersection with the x-axis at higher spatial frequencies leads to an estimation of the visual acuity. RESULT: This result is compared to the subjectively determined visual acuity. In the majority of the presented cases the suspected malingering was confirmed. CONCLUSION: Patients with suspected malingering represent the primary indication of the described method.

Adult↗
PubMed1998

Prognostic value of the pattern electroretinogram in cases of tumors affecting the optic pathway.

BACKGROUND: Tumors compressing the optic pathway may lead to irreversible loss of vision which may be detected by the pattern electroretinogram (PERG) because of its relation to ganglion cell function. METHODS: Eyes of 19 patients were tested shortly before and 5-10 days after tumor surgery. Visual acuity, the 30-deg visual field and the transient and steady-state pattern reversal ERG were measured. RESULTS: Using patterns of 1.5 x 1.2 deg there was a good correlation between the change of pre- and post-surgical visual performance and most of the pattern ERG amplitudes. For all variables tested--P50, N95- and steady-state amplitude--there was a critical value beyond which the visual outcome could be bad or favorable, whereas patients showing higher amplitudes always remained stable or improved after surgery. CONCLUSION: The positive correlation between pattern ERG amplitudes and the post-surgical outcome in the case of tumors affecting the optic pathway may be helpful in predicting the outcome for these patients.

Adolescent↗
PubMed1998

Multifocal electroretinography in retinitis pigmentosa.

PURPOSE: To investigate the diagnostic potential of multifocal electroretinography for the evaluation of retinal affection by retinitis pigmentosa in a clinical setting. METHODS: For this prospective study, multifocal electroretinograms were obtained from 38 patients who matched the inclusion criteria of either a detectable photopic Ganzfeld response or visual fields of 10 degrees or more, and from 30 normal volunteers. Recordings were performed with the visual evoked response imaging system, using a resolution of 61 hexagonal elements within a 30-degree visual field. The results of the left eye of each patient and control subject were used for statistical evaluation by the Mann-Whitney U test. RESULTS: The 38 eligible patients included those with Usher syndrome types I and II (one patient and six patients, respectively) and those with autosomal-recessive (18), X-recessive (two), and autosomal-dominant (11) forms of retinitis pigmentosa. In 27 (71%) of these 38 patients, at least a central response of the multifocal electroretinogram was detectable. Loss of multifocal electroretinogram response density in patients with retinitis pigmentosa was significant (P < .00001) in all five eccentricity groups (concentric rings), with a progression from center to periphery. Implicit time was significantly elevated in the third eccentricity group (P < .0038) and increased further toward the periphery (P < .00001). The results did not differ notably between retinitis pigmentosa subgroups. CONCLUSIONS: Because the multifocal electroretinogram differentiates between affected and nonaffected retinal areas, eccentricity-dependent changes in both amplitude and implicit time were found. It can therefore add to the diagnostic information of many patients with retinitis pigmentosa.

Adolescent↗
PubMed1998

An L-type calcium-channel gene mutated in incomplete X-linked congenital stationary night blindness.

The locus for the incomplete form of X-linked congenital stationary night blindness (CSNB2) maps to a 1.1-Mb region in Xp11.23 between markers DXS722 and DXS255. We identified a retina-specific calcium channel alpha1-subunit gene (CACNA1F) in this region, consisting of 48 exons encoding 1966 amino acids and showing high homology to L-type calcium channel alpha1-subunits. Mutation analysis in 13 families with CSNB2 revealed nine different mutations in 10 families, including three nonsense and one frameshift mutation. These data indicate that aberrations in a voltage-gated calcium channel, presumably causing a decrease in neurotransmitter release from photoreceptor presynaptic terminals, are a frequent cause of CSNB2.

Amino Acid Sequence↗
PubMed1997

Molecular basis of choroideremia (CHM): mutations involving the Rab escort protein-1 (REP-1) gene.

Choroideremia (CHM) is an X-linked recessive eye disease that results from mutations involving the Rab escort protein-1 (REP-1) gene. In 18 patients deletions of different sizes have been found. Two females suffering from CHM were reported to have translocations that disrupt the REP-1 gene. In 22 patients, small mutations have been identified. Interestingly, these are all nonsense, frameshift or splice-site mutations; with one possible exception, missense mutations have not been found. This comprises all the known mutations in the disease.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Ocular findings in patients with autosomal dominant retinitis pigmentosa and Cys110Phe, Arg135Gly, and Gln344stop mutations of rhodopsin.

This report describes ocular findings obtained in four patients from three families with autosomal dominant retinitis pigmentosa (adRP) due to missense mutations in the rhodopsin gene. Phenotypes were characterized by standard ophthalmologic examinations, visual fields, electroretinography (ERG), dark adaptation, and two-color dark-adapted threshold perimetry. Two patients aged 38 and 45 years, respectively, from a family with the Cys110Phe mutation showed mild fundus changes without bone spicules as well as small arcuate scotomas in the inferior quadrants of their visual fields but displayed severe functional loss of rods and cones in the ERG. Two-color dark-adapted threshold perimetry revealed a regional type of degeneration. A 48-year-old patient with an Arg135Gly mutation had typical RP with concentrically narrowed visual fields and nondetectable ERG responses. Central visual functions were well preserved for a long time. Two-color dark-adapted threshold perimetry indicated a diffuse type of retinal degeneration. An 18-year-old patient with a Gln344stop mutation has been followed for 13 years. His ERG was clearly reduced at the age of 5 years; since that time, disease progression has been very slow. Currently, there are relatively mild alterations in visual acuity, rod sensitivity, and visual fields. Our findings confirm that there is a large phenotypic variety among patients with adRP and different rhodopsin mutations.

Adolescent↗
PubMed1997

[Juvenile neuronal ceroid lipofuscinosis (Batten-Mayou) disease. Ophthalmologic diagnosis and findings].

BACKGROUND: Juvenile neuronal ceroid lipofuscinosis (JNCL) is important to the ophthalmologist, since eye symptoms are usually the first evidence of the disease and permit establishment of an early diagnosis. The disorder usually begins with a dramatic loss of vision between age 4 and 10 due to bulls-eye maculopathy followed by rapid degeneration of the retina and pigment epithelium. Blindness results within 1 to 3 years after onset of symptoms. The further course of the disease is mainly determined by degradation of the CNS with motor and intellectual deficits. Most patients die before the age of 30. METHODS: A case of two sisters is presented to demonstrate eye findings and diagnostic procedures, emphasizing electrophysiologic and morphologic tests (peripheral blood smear, histology). RESULTS: Both sisters reported the first decrease in vision at the ages of 8 and 6 respectively; visual acuity at time of visit was light projection (20/400). Both had tapetoretinal degeneration with optic disc atrophy, narrowed vessels, pigment epitheliopathy and bullseye maculopathy. The ERG was almost extinguished in the older sister and greatly reduced in the younger one (scotopic more than photopic). Histologically, vacuolated lymphocytes were found in the peripheral blood smear, as were intracellular inclusions of the fingerprint and curvilinear type in the conjunctival biopsy. CONCLUSION: During the course of JNCL, it is very common for the vision to be affected at the age of 6-7. The correct diagnosis, however, is often made years later when massive neurologic symptoms such as seizures appear. When there is sudden loss of vision in a child of this age combined with a tapetoretinal degeneration, a biopsy or at least a peripheral blood smear should be performed.

Biopsy↗