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Biomedical subjects

G Kommerell

Publications and source records attributed to G Kommerell.

At least 37 records · Page 2Linked to original sources
PubMed1996

Relative absence of psychopathology in benign essential blepharospasm and hemifacial spasm.

We report on the psychopathology and illness-related changes of life in patients with benign essential blepharospasm (BEB) or hemifacial spasm (HFS). Fifty-six patients with BEB and 40 patients with HFS completed the SCL 90R, a screening instrument for psychiatric symptomatology, and the Freiburg Questionnaire for Dystonia (FQD), a questionnaire about psychosocial changes in subjects with movement disorders. In both BEB and HFS patients, the mean scores on all but one subscale of the SCL 90R remained within the double standard deviation of normal. In comparing BEB to HFS patients in illness-related changes of life, BEB patients were more severely disabled in all areas of life examined. Psychological distress in BEB, but not in HFS, correlated with physical disability and in particular with impairment of vision.

Analysis of Variance↗
PubMed1996

[Filling of optico-ciliary shunt vessels in papilledema: an indicator of pressure in the optic nerve sheath].

BACKGROUND: Optico-ciliary shunt vessels can occur in papilledema. It appears possible that the diameter of these vessels correlates with the pressure in the optic nerve sheath. CASE REPORT: A 31-year-old woman with pseudotumor cerebri had atrophic papilledema with optico-ciliary shunt vessels at the disc margin. After optic nerve sheath fenestration these vessels collapsed and ultrasonography revealed a decrease in the nerve sheath diameter. Sixteen days later, the optico-ciliary shunt vessels were filled again. Nine hours after lumbar puncture, the optico-ciliary shunt vessels disappeared for 13 hours, but the nerve sheath diameter did not decrease. After acetazolamide, 1g q d, neither the diameter of the optico-ciliary shunt vessels nor that of the nerve sheath decreased. CONCLUSION: The diameter of optico-ciliary shunt vessels may be an indicator of the pressure within the optic nerve sheath.

Adult↗
PubMed1995

Asymmetry of motion VEP in infantile strabismus and in central vestibular nystagmus.

Norcia et al. [1] found a nasal-temporal asymmetry of visually evoked potentials (VEP) elicited by motion stimuli in patients with infantile strabismus. Patients with infantile strabismus typically present with an asymmetry of the monocular optokinetic nystagmus (OKN). We here address the question whether the asymmetry of the motion VEP indicates a sensory defect in the afferent visual pathway that could explain the OKN asymmetry. We recorded the VEP to a horizontally oscillating vertical sinusoidal grating in 20 patients with infantile strabismus (esotropia, asymmetry of the monocular optokinetic nystagmus, latent nystagmus) and in 10 normal controls. No asymmetry occurred in the 10 controls. Eight of the 20 patients with infantile strabismus showed a clear difference between the VEPs evoked by back and forth movements with a mirror-like asymmetry between the two eyes (phase shift 180 +/- 20 degrees). However, there was no significant correlation between the degree of VEP and OKN asymmetries. Therefore, we assume that the VEP asymmetry does not reflect the primary cause of the OKN asymmetry. Rather, the OKN asymmetry may be due to a sensory-motor defect in the efferent subcortical pathway, and the VEP asymmetry could be an epiphenomenon. Some of the VEP asymmetry may be a consequence of the latent nystagmus typically released under monocular stimulation, leading to adaptation of the afferent retino-cortical pathway. This suggestion is supported by a marked VEP asymmetry that we found in two patients with an acquired central vestibular nystagmus, an abnormality most likely not combined with a primary defect of the retino-cortical pathway.

Adolescent↗
PubMed1995

[Simulation of anterior ischemic optic neuropathy by optic nerve sheath meningioma].

BACKGROUND: The optic nerve sheath meningioma usually presents with a diffuse atrophy of the disc and a diffuse depression of the visual field. Applying this rule too rigidly can lead to a false diagnosis. PATIENT: A 45y-old-woman presented with atrophy of the upper disc and a corresponding altitudinal field defect in her right eye. AION was diagnosed. Seventeen years later the patient returned with an exophthalmus. The disc was atrophic and a shunt vessel connected the central retinal vein with the choroid. CT revealed an orbital mass. The diagnosis of an optic nerve sheath meningioma was made and confirmed at surgery. DISCUSSION: The meningioma may have occluded an upper posterior ciliary artery, mimiking an AION. Alternatively, the meningioma may have destroyed the fibers running through the upper half of the disc and caused swelling of the remaining fibers in the lower half of the disc. CONCLUSION: In the combination of swelling and atrophy of one disc an optic nerve sheath meningioma should be considered, even if the two components are located in different sectors. In optic nerve sheath meningioma vision decreases insidiously as opposed to the acute drop typical for anterior ischemic optic atrophy.

Cranial Nerve Neoplasms↗
PubMed1995

[Motility and binocular function after radial episcleral buckle].

BACKGROUND: The incidence of motility disturbances induced by episkleral buckle operations for retinal detachment has been reported to range between 7 and 77%. We anticipated a relation between the buckle size and the incidence and extent of motility disturbances. PATIENTS AND METHODS: We examined 45 patients 2 to 4 years after successful retinal detachment surgery with a radial buckle. The buckle diameter was 3-11 mm. Patients were examined for diplopia and heterophoria in the primary position and in 20 degrees secondary and tertiary gaze deviations. Stereopsis was determined using the TNO plates. Refractive error and visual acuity were also measured. RESULTS: Heterophoria measurements in the various directions of gaze revealed a hypermotility in 22/45 cases. A hypomotility was encountered only in one of the 45 cases. In 40 of the 45 cases the field of binocular single vision had a radius of at least 20 degrees. 39 of the 45 patients had stereopsis (after macular detachment 17/22, without macular detachment 22/23). 7/32 patients with a buckle of > or = 5 mm reported on diplopia, but none of the 13 patients with a buckle of < or = 4 mm. Heterotropia in the primary position was found in one of the 45 cases. He had three buckles, a 10.5 mm buckle under the superior rectus muscle of one eye and a 4 and 7.5 mm buckle under the inferior oblique and rectus muscles of the other eye. The resulting vertical deviation was successfully treated with prisms. Motility disturbances in the upper field of gaze were found in 2 of 45 cases with buckles of 5 and 7.5 mm. Diplopia was not permanent in these cases. DISCUSSION: Hypermotility towards the position of the buckle may be explained by a deviation of the adjacent rectus muscles, after sharp preparation and shrinkage of the intermuscular septum. CONCLUSION: Since motility disturbances were encountered only with buckles of > or = 5 mm, small buckles (< or = 4 mm) should be applied whenever possible.

Adult↗
PubMed1995

[Psychometric function of stereo disparity in normal persons].

UNLABELLED: The accuracy and efficiency of threshold estimation depend on a priori knowledge of the shape of the psychometric function. Such knowledge is available for contrast detection and visual acuity, but not for disparity detection. METHODS: We studied the psychometric function for disparity detection in 26 visually normal, untrained observers by measuring detection rates over a wide range of disparities. In a two-alternative forced-choice (2AFC) task the subject had to decide whether the right or left of two vertical bars, differing in depth, was closer to them. An S-shaped Weibull function was fitted to each subjects's data using the maximum-likelihood procedure. RESULTS: In 21 of the 26 subjects the psychometric function rose with increasing disparities up to a level of about 100%. Five of the 26 subjects only reached hit rates clearly below 100% (66% to 82%), even at disparities well above the threshold. The mean slpe of the S-shaped psychometric function of disparity detection was much lower (1.2 Weibull units) than that known for visual acuity and contrast detection (about 3.0 Weibull units). The slope differed widely among subjects, but was not related to stereo acuity. CONCLUSION: For accurate and efficient estimation of stereo acuity, the shallow slope of the psychometric function requires more than 100 single trials around the threshold if a 2AFC procedure is used. In addition, several disparities well above the threshold must be presented in order to detect subjects who do not reach a hit rate of 100% at any disparity. Otherwise, stereo acuity would be underestimated in these subjects.

Adult↗
PubMed1994

The dynamic head-tilt test and the concept of a supranuclear trochlear palsy.

The "dynamic head-tilt test" introduced in this article examines the influence of the vestibular semicircular canals on the eye muscles during the head tilt. Normally, a rotatory nystagmus results. If under certain pathological circumstances, the vestibulo-ocular reflex is transmitted only to the rectus muscles and not to the obliques, the cyclorotatory nystagmus is converted into a vertical nystagmus. We have found this condition in five cases; in two it was very pronounced. During head tilt to the right, the slow phases of the nystagmus were directed upward in the right eye and downward in the left eye. During head tilt to the left, the nystagmus directions were reversed. Since other signs of oblique muscle palsy such as incomitance and cyclotropia were lacking or inappropriately slight, the author suggests the presence of a supranuclear lesion eliminating the vestibular input to the trochlear nucleus and to the subnucleus of the inferior oblique muscle while leaving the input for voluntary and visual gaze signals intact.

Adult↗
PubMed1993

Stereoscopic cooperation between the fovea of one eye and the periphery of the other eye at large disparities. Implications for anomalous retinal correspondence in strabismus.

In normal human observers we searched for the largest amount of visual disparity that can still provide depth information; we compared (1) crossed and uncrossed disparities and (2) symmetrical and asymmetrical locations of disparate stimuli. A pair of 3 degrees discs projected for 100 ms served as targets. Symmetrical stimuli were projected on temporal or nasal retinal loci in both eyes; asymmetrical stimuli were projected on the fovea of one eye and on the nasal or temporal periphery of the other eye. Thresholds were determined using a two-alternative forced choice procedure. Subjects had to distinguish binocular disparate images from monocular double images of identical angular separation. Among six subjects, crossed disparities were recognized by one up to 6 degrees, by three up to 9 degrees, by one up to 18 degrees, and by one up to 21 degrees. Uncrossed disparities were recognized by two at 3 degrees, by two up to 6 degrees and by two up to 9 degrees. Hence, crossed disparities could be recognized up to higher angles than uncrossed. No consistent difference was found between symmetrical and asymmetrical stimuli. Stimuli with crossed disparity appeared smaller and with uncrossed disparity larger than monocular stimuli of the same objective size, suggesting that the size-constancy mechanism operates when disparity stimuli are presented as briefly as 100 ms, i.e., without simultaneous vergence eye movements. We speculate that the far-reaching interocular connections demonstrated in normal subjects might also be utilized in the case of strabismus: these interocular connections could form the basis for anomalous retinal correspondence.

Adult↗
PubMed1993

[The Freiburg Stereotest. On assessment of stereovision in automobile driver examination].

BACKGROUND: The "Freiburg Stereotest" is a new instrument where disparate pictures are generated by a computer and displayed on one single high resolution video monitor. In the present work, the Freiburg Stereotest was used to check the stereo qualification for certain categories of driver's licence. For this purpose, a determination of the smallest detectable disparity is not reasonable. Rather, it should be checked whether or not a certain disparity, usually well above threshold, is recognized with a sufficient reliability. We have chosen a disparity of 100 arcsec; this value is considered to be an acceptable requirement for certain categories of driver's licence. SUBJECTS AND METHODS: 6 strabismic subjects were examined binocularly and 10 normal subjects were examined both binocularly and monocularly. Two targets ("busses"), side by side and different in depth by a disparity of 100 arcsec, were presented 78 times and, in a two-alternative forced-choice procedure, a minimum of 66 hits was required to pass the test. Monocular cues were excluded by a systematic variation of the lateral distance between the two targets. RESULTS: The strabismic subjects and the monocularly occluded normal subjects reached random scores only. With both eyes open, 8 of the 10 normal subjects reached scores near 100%, while 2 of them passed the test only when the lateral distance between the two targets was 15 minarc or less. For a lateral distance between the two targets of more than 15 minarc, these 2 subjects showed a learning effect. CONCLUSIONS: The Freiburg Stereotest allows to determine with statistical significance whether or not a proband can recognize a certain disparity which may be required for a driver's licence.

Adult↗
PubMed1993

[Streak retinoscopy. Optical principles and practical recommendations].

The optical principles of streak retinoscopy are demonstrated by diagrams and by optical models. The phenomena observed in the proband's pupil are being explained in two ways: In the first explanation, the image on the proband's retina and its movements are considered, or rather their projection into space; this explanation corresponding to the term "retinoscopy" is commonly used in English textbooks. In the second explanation, the limitations of the light bundle by the proband's and the observer's pupils are considered; hence the term skiascopy (sigma kappa iota alpha = shadow), commonly used in the German literature. The practical hints include retinoscopy through the phoropter, suggestions for the examination of children both with and without cycloplegia, the measurement of accommodation, the detection of opacities and irregularities in the optical media, and the analysis of visual field defects caused by optical anomalies, such as refraction scotomas.

Accommodation, Ocular↗
PubMed1993

[Monocular diplopia caused by pressure of the upper eyelid on the cornea. Diagnosis based on the "Venetian blind phenomenon" in streak retinoscopy].

BACKGROUND: Abnormal pressure from the upper eye lid can cause a kink in the corneal vault along the lid margin. Depending on whether the lower or upper part of the lid exerts the higher pressure, the upper segment of the cornea acquires a prismatic effect which is base up or down, respectively. This causes a ghost image below or above the main image. In patients whose upper eye lid occasionally reaches down such that the kink traverses the pupillary area, the ghost image appears whenever they raise their lid above its usual position. The purpose of the present paper is to describe a retinoscopic phenomenon that allows an easy diagnosis of this condition. PATIENTS AND METHODS: About 20 patients with a ghost image below or above the main image were examined with a Placido disc, with a photokeratometer, and with a streak retinoscope. RESULTS: Photokeratometry revealed a slight deformation of the ring reflexes along a horizontal line at the border of the upper third of the cornea. This deformation was obvious only in a minority of the patients. The retinoscopic findings were more characteristic. With the streak horizontal, two or three light bands separated by dark intervals were seen in a "with movement", suggesting the impression of a Venetian blind being lowered or raised behind the pupil. Because of this impression, the author suggests the term ""Venetian blind phenomenon." DISCUSSION AND CONCLUSION: Monocular diplopia caused by abnormal lid pressure can be easily diagnosed by the "Venetian blind phenomenon". The optics can be explained as follows. Both the beams entering into, and emerging out of the patient's eye are being split by the prismatic effect of the upper cornea. Principally, this should result in four images; since, however, two of them overlay each other, only three separate images remain. In cases where the upper cornea is deflected backwards, resulting in a prismatic effect base down, the examiner can see all three images. In cases where the upper cornea is deflected forwards, resulting in a prismatic effect base up, the beams emerging from the patient's eye diverge, and the uppermost beam falls upon the examiner above his pupil, so that he can see only two of the three images.

Adult↗
PubMed1993

[Peripheral retinal correspondence after retinal detachment].

BACKGROUND: Occasionally, patients who underwent surgery for complicated retinal detachment report spatial distortions. This may be due to a translocation of photoreceptors when they become reattached to the pigment epithelium. We wanted to find out if, and to what extent, similar translocations occur after a simple buckling operation. METHODS: Binocular retinal correspondence was used as an indicator of photoreceptor translocation. Correspondence was measured in the peripheral visual field at eccentricities of 5, 10 and 20 degrees, using a mirror haploscope. We examined two normal observers, one patient having had surgery for complicated retinal detachment including retinotomy, and 23 patients who had simple radial buckling operations. RESULTS: The patient who had received complicated detachment surgery including retinotomy revealed a tremendous shift in correspondence. Of the 23 patients who had simple radial buckle operations, only 10 were able to sustain central fixation while being tested in the periphery. Of these 10 patients, 2 showed distortions of peripheral retinal correspondence in the area of previous retinal detachment. However, only one of them remembered some spatial distortion after surgery. CONCLUSION: As a rule, photoreceptors become correctly reattached after radial buckle operations for retinal detachment. Rarely, vertical or horizontal translocations of about 1 to 2 degrees occur, but this does not usually lead to metamorphopsia.

Adult↗
PubMed1993

Latent nystagmus. Release and suppression at will.

PURPOSE: The authors report the cases two unusual patients with infantile convergent strabismus and latent nystagmus. METHODS: Electronystagmography was used. RESULTS: The two patients were able to release and suppress their nystagmus at will. With voluntary effort, the nystagmus became as strong as it was when brought out by occlusion of the squinting eye and, in one of the patients, even stronger. The nystagmus beat toward the fixing eye, and the slow phases had slightly decreasing velocity or were linear. Both patients were able to evoke and to stop the nystagmus in front of visual contours and, one of them, also in the dark. CONCLUSIONS: This phenomenon could be the result of voluntary control of the visual input contributed by the amblyopic eye and/or a direct influence of will on the slow eye movement and fixation systems. A mechanism related to vergence eye movements is less likely. The ability to release and suppress a latent nystagmus at will is unusual and, to the authors' knowledge, has not been described before.

Adult↗
PubMed1993

[The Freiburg Vision Test. A computer-assisted procedure with sequential strategy].

Single Landolt Cs were presented in one of four positions on a monitor. Subjects responded by pressing one of four buttons (forced choice). A computer selected the size of the Landolt Cs on a logarithmic scale using the "Best PEST" algorithm (Best Parameter Estimation by Sequential Testing), a modern procedure to measure psychophysical thresholds. For comparison, conventional measurements according to DIN 58220 (Deutsche Industrie Norm) were performed with Landolt Cs projected in eight positions, using three out of five correct responses as the threshold criterion. Examination of 23 patients (most of them with senile cataract) did not show any significant difference between the two tests in either visual acuity or reproducibility on two consecutive days. The coefficients of variation between sessions were 22% for the Freiburg test and 26% for the DIN test and 18% between the two tests, pooled over two sessions. The Freiburg acuity test thus appears to be numerically equivalent to the DIN 58220 procedure. In addition, it has a number of advantages: (1) examiner-dependent variability is reduced; therefore, the test can be used by inexperienced examiners; (2) the forced choice technique is used rigorously; (3) mistakes in confounding oblique directions are largely avoided; (4) the procedure is about twice as fast.

Adult↗
PubMed1992

Misdirected regeneration of abducens nerve neurons into the parasympathetic pupillary pathway.

A 16-year-old girl suffered a severe head trauma with paralyses of the right oculomotor, trochlear, and abducens nerves. Three years later, only the abducens nerve had recovered. The pupil did not react to light or near. However, the diameter of the pupil correlated with horizontal gaze: with the gaze to the left, the diameter of the pupil was 8 mm, with the gaze straight ahead, 6 mm, and with the gaze to the right, 4 mm. With saccades to the right, the pupil started to constrict immediately and reached its smallest diameter after about 2 s. We conclude that the constriction of the pupil was due to misdirected regeneration of abducens nerve neurons into the parasympathetic pathway of the oculomotor nerve.

Abducens Nerve↗