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Biomedical subjects

A Thaler

Publications and source records attributed to A Thaler.

At least 19 recordsLinked to original sources
PubMed2005

Evaluating reading acuity and speed in children with microstrabismic amblyopia using a standardized reading chart system.

BACKGROUND: To examine if standardized reading charts with highly comparable test items can be used for evaluating impairments in the monocular reading performance of children with microstrabismic amblyopia characterized by a small angle of squint with less than 5 degrees. METHODS: The reading performance of 22 children (mean age: 11.7+/-1.6 years) with unilateral microstrabismic amblyopia was evaluated monocularly in both eyes, using standardized reading charts for the simultaneous determination of reading acuity and speed. The print sizes of the highly comparable sentence optotypes were logarithmically graded, providing constant geometric proportions for all testing distances in order to control contour interaction. All children were under continuous amblyopia therapy. RESULTS: In the amblyopic eyes, reading acuity and maximum reading speed were significantly impaired when compared to the sound fellow eyes (P<0.001). In respect of the maximum reading speed, a mean inter-ocular difference of 33+/-19 words per minute was found, revealing functionally relevant deficits in monocular reading performance. The amblyopic eyes achieved only a significantly reduced reading acuity (mean inter-ocular difference: LogRAD 0.5+/-0.24; P<0.001). In eight children, the amblyopic eyes achieved a best-corrected visual acuity of LogMAR 0.0 or better: in respect of the visual acuity, there was no significant inter-ocular difference, but reading acuity and maximum reading speed were significantly impaired when compared to the fellow eyes. CONCLUSIONS: Microstrabismic amblyopia was associated with significant impairment of reading acuity and speed in treated amblyopes, even in those with no persistent acuity deficit. To improve treatment addressing these functional deficits, reading performance should be monitored over time using standardized reading tests, which provide essential information about functionally relevant reading impairments.

Amblyopia↗
PubMed2005

Monocular and binocular reading performance in children with microstrabismic amblyopia.

AIM: To evaluate if functionally relevant deficits in reading performance exist in children with essential microstrabismic amblyopia by comparing the monocular and binocular reading performance with the reading performance of normal sighted children with full visual acuity in both eyes. METHODS: The reading performance of 40 children (mean age 11.6 (SD 1.4) years) was evaluated monocularly and binocularly in randomised order, using standardised reading charts for the simultaneous determination of reading acuity and speed. 20 of the tested children were under treatment for unilateral microstrabismic amblyopia (visual acuity in the amblyopic eyes: logMAR 0.19 (0.15); fellow eyes -0.1 (0.07)); the others were normal sighted controls (visual acuity in the right eyes -0.04 (0.15); left eyes -0.08 (0.07)). RESULTS: In respect of the binocular maximum reading speed (MRS), significant differences were found between the children with microstrabismic amblyopia and the normal controls (p = 0.03): whereas the controls achieved a binocular MRS of 200.4 (11) wpm (words per minute), the children with unilateral amblyopia achieved only a binocular MRS of 172.9 (43.9) wpm. No significant differences between the two groups were found in respect of the binocular logMAR visual acuity and reading acuity (p>0.05). For the monocular reading performance, significant impairment was found in the amblyopic eyes, whereas no significant differences were found between the sound fellow eyes of the amblyopic children and the control group. CONCLUSION: In binocular MRS, significant differences could be found between children with microstrabismic amblyopia and normal controls. This result indicates the presence of a functionally relevant reading impairment, even though the binocular visual acuity and reading acuity were both comparable with the control group.

Amblyopia↗
PubMed2000

Separation and quantification of alkylphosphocholines by reversed phase high performance liquid chromatography.

Alkylphosphocholines represent a new class of drugs with remarkable antineoplastic and antiprotozoal activity. For instance, hexadecylphosphocholine has been approved for the topical treatment of skin metastasis. In addition, it was successfully studied in India for the treatment of leishmaniasis. Different phase-I and phase-II-trials resulted in cure rates of more than 97%. To optimize antitumor or antiprotozoal activity, we have prepared alkylphosphocholines differing in chain length and unsaturation. For the qualitative and quantitative analysis of these longer chain analogues, we have used isocratic high performance liquid chromatography. The separation of the alkylphosphocholines with different chain lengths in this reversed phase HPLC system was achieved on a YMC-TMS column with a mobile phase consisting of methanol-water (85:15; v/v) at a flow rate of 1.0 ml/min. Furthermore the cis-/trans-isomers such as oleylphosphocholine and elaidylphosphocholine were clearly separated on a YMC-C8 column with a methanol-water mixture (80:20; v/v) as mobile phase. In the described reversed phase HPLC systems simple refractive index detection and UV detection allow the sensitive and quantitative determination of alkylphosphocholines. These methods are very important for reproducible identification and quantitative determination of saturated and mono-unsaturated alkylphosphocholines with alkyl residues containing up to 25 carbon atoms.

Chromatography, High Pressure Liquid↗
PubMed1997

[Visual rehabilitation: magnifying vision aids].

Many retinal diseases can be treated either with laser treatment or with vitreo-retinal surgery. However, in some of these cases a severe visual loss cannot be avoided and visual rehabilitation has to be initiated. Visual rehabilitation is initially performed by fitting low vision aids. With low vision aids the patients ability to read can be restored as well as many other needs of every days life e.g. reading bus numbers, street names, bank notes or letters. In analogy with the higher life expectancy in the middle european countries the incidence of age related maculopathy will increase in the next years. Thus, the need for visual rehabilitation will increase as well.

Adult↗
PubMed1993

The dark trough in clinical electro-oculography. Influence of preadaptation on amplitudes and latencies.

The influence of four different intensities of the preadapting light on amplitude and implicit time of the dark-induced oscillation (dark trough) of the electro-oculogram was tested in 10 healthy individuals. The amplitude of the dark trough (normalized to preadapting baseline) was found to be dependent on the intensity of the preadapting light (analysis of variance: p < 0.0001). No correlation could be proven between preadapting light intensity and the implicit time of the dark trough (p = 0.299). The confidence intervals of the implicit time of the dark trough exceeded 14 minutes in all four intensity settings. There was no significant dependence of the absolute baseline values on preadapting intensities (p = 0.236).

Adult↗
PubMed1993

Comparison of electro-oculogram recording methods.

The purpose of this study was to compare the variability of the amplitude ratios and latencies of the electro-oculogram (EOG) light peak (LP) in three different recording conditions: Arden ratio (dark trough (DT): 12 min), modified Arden ratio (DT: 15 min) and light peak/dark baseline ratio (LP/BL: 35 min of dark adaptation). Additionally, EOGs from eyes with dilated and undilated pupils were recorded. The light intensity stimulating the eyes with dilated pupils was attenuated 1 log unit. The EOG amplitude ratios displayed no significant difference between the three conditions tested. The comparison of implicit times (time from onset of light exposure to LP) revealed significantly (p < 0.001) shorter values when the recording of the LP was preceded by a dark adaptation of 35 min. The broadening of the curves in DT/LP recordings might be caused by a superposition of a residual dark oscillation on the LP. The recordings from eyes with dilated pupils--stimulated with 1 log unit lower intensity--revealed lower amplitude ratios than the recordings from eyes with undilated pupils.

Dark Adaptation↗
PubMed1993

Prostacyclins in diabetes: an electrophysiological study.

Twelve patients with juvenile (insulin-dependent, type I) diabetes were treated either with prostacyclins or placebo in a double-masked randomized study. The electroretinogram (ERG) was recorded before, 1 day and 8 months after treatment. An analysis of variance and covariance was carried out to evaluate possible treatment or time effects on the a and b waves and the oscillatory potentials of the ERG. Mean values of potentials displayed a decrease of amplitude and an increase of latency over the follow-up period in all patients. No statistically significant difference between treated and placebo groups could be proven.

Adult↗
PubMed1991

Intraoperative retinal light damage reflected in electrophysiologic data.

In a series of 30 unilaterally pseudophakic patients, electroretinograms and electrooculograms were recorded 6 months postoperatively. The unoperated on fellow eyes served as controls. High intraoperative retinal light exposure (3.4-7.3 mW/cm2, Zeiss OPMI6 operating microscope) caused a substantial reduction of electrophysiologic potentials. Light protection prevented deterioration of electroretinogram and electro-oculogram potentials; reducing the bulb voltage, tilting the axis of illumination, filtering short wavelengths and the use of light shields resulted in 4-log-unit lower intensities (0.8-3.7 microW/cm2).

Aged↗
PubMed1989

The slow electrooculogram oscillation in malignant choroidal melanoma.

Electrooculographic recordings were performed in a series of patients with malignant choroidal melanoma. The amplitudes of the light peaks were reduced in all cases compared with the recordings of the normal fellow eyes. The amount of reduction of the light peaks appeared to be dependent on localization of the tumor. The electrooculograms of eyes with tumors of the posterior pole were found to be reduced significantly. Eyes with malignant melanomas located in the peripheral fundus displayed minor reductions.

Adult↗
PubMed1989

The peak latency of the slow oscillation in EOG.

Peak latencies of the light-induced slow electrooculograph oscillations of 61 patients were analyzed. The wide range of variation of the results of the control group obtained in this study did not allow inferences relevant for the differential diagnosis of retinal diseases. Most of the data were within the limits of normal values.

Electrooculography↗
PubMed1988

The c-wave in achromats.

In congenital total color blindness direct current recordings of the electroretinogram displayed a negativity following the b-wave, not present in recordings of normal eyes. This negativity, preceding the onset of the c-wave, is probably caused by the lack of cone contribution to the positive c-wave component.

Child, Preschool↗
PubMed1987

[Screening and monitoring studies on employees working with video display terminals].

Ophthalmological screening of 152 employees working at VDUs was carried out. In 62% of the people tested spectacles were prescribed for correction of vision at working range. Two years later a follow-up examination was performed. The correction had to be revised for 23% of the people working et VDUs. It is recommended that ophthalmological screening should not be restricted to people working at VDUs. All employees whose work involves close-range vision require regular ophthalmological check-ups.

Data Display↗
PubMed1986

ERG and EOG in progressive paravenous retinochoroidal atrophy.

A case of paravenous retinochoroidal atrophy was followed over a period of more than 2 years. Rapid progression of the disease was reflected in the deterioration of visual acuity and fields. Electroretinographic recordings revealed reduced photopic and scotopic amplitudes according to the extent of the retinal lesions. In electrooculography virtually no slow and no fast light-induced oscillations could be recorded. These results suggest an involvement of the entire retinal pigment epithelium.

Adult↗
PubMed1986

The influence of intravitreously injected silicone oil on electrophysiological potentials of the eye.

In a prospective study the effect of silicone oil injected in the vitreous cavity was monitored electrophysiologically in six patients who were treated for retinal detachment. Electroretinograms (ERG) and electrooculograms (EOG) were recorded before, shortly after, and up to four months following the removal of the oil. An evident increase of the standing potential could be observed in all eyes after removal of the silicone oil. In some patients the ERG amplitudes increased also. No fast oscillations and virtually no slow oscillations could be recorded in the EOG. Follow-up studies did not show a significant recovery of the bioelectric activity. Intravitreal silicone oil appears to cause an insulation effect which interferes with the propagation of electrical potentials. The result of the present study do not provide information concerning possible retinotoxic effects of silicone oil.

Electrooculography↗
PubMed1981

[The hereditary factor as a criterion for the classification of stationary congenital night blindness (author's transl)].

The night-blind subject examined in 1952 by Schubert and Bornschein was reexamined electrophysiologically. All findings were unchanged. Normal a, d and g-waves in the ERG indicated undisturbed receptor function. Fast and slow oscillations of the EOG were normal. The subjective darkness-adaptation curve revealed minimal scotopic function after the 14th min of adaptation. The significance of clinical and electrophysiological findings for the classification of stationary congenital night blindness is discussed. The hereditary factor appears to be the most preferable criterion for the classification of stationary congenital night blindness.

Dark Adaptation↗
PubMed1980

[Unilateral pigmentary degeneration of the retina].

A case of unilateral pigmentary degeneration of the retina was followed up over a period of 36 years. Clinical and electrophysiological findings of the affected eye resemble those of retinitis pigmentosa. The fellow eye is normal. The family history is negative. Therefore, the diagnosis of unilateral retinitis pigmentosa is not beyond dispute. Regardless of the long observation period the existence of unilateral pigmentosa could not be proven.

Adult↗