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Biomedical subjects

H F Piper

Publications and source records attributed to H F Piper.

At least 19 recordsLinked to original sources
PubMed2000

How do the corresponding eyes avoid disturbing contour overlaps? Historical answers (1859 - 1981).

The visual system has a limited capacity to fuse overlapping impressions. It takes advantage of three principles of organization: (1) The mixing of different impressions resulting in a new entity (compensation principle); examples are the mixing of colors, dark and light at the retina, Fechner's paradox. The twelve researchers whose work is reported here analyzed two other unifying principles: (2) Selection by successive contrasts (polarization principle) and (3) subordination in a hierarchy of vision (differentiation principle).

History, 19th Century↗
PubMed1999

[Peter Ludvig Panum's sensory physiological works from his years in Kiel 1853-1864].

In 1858 Panum published a monography on "Physiologische Untersuchungen über das Sehen mit zwei Augen". He proposed the concept of corresponding circles of perception instead of the absolute identity of corresponding points on the retina. This was met with opposition particularly by A. W. Volkmann of Halle who tried to explain psychologically all stereoscopic phenomena (Arch. Ophthalmol., 1859). Both authors defended their views with numerous experiments. Panum's results in "Uber einheitliche Verschmelzung verschiedenartiger Netzhauteindrücke beim Sehen mit zwei Augen" (Arch. Anatomie, 1861) is still valid today.

Depth Perception↗
PubMed1998

[Automobile driving fitness of patients with nystagmus].

BACKGROUND: By law, applicants for driver's licenses not only have to have sufficient vision, but also have to use this sight reliably. The nystagmus patient takes advantage of ocularly induced head turns and other forms of compensation. In the approved test procedures he is deprived of such compensations. MATERIALS AND METHODS: The eye movements of a nystagmus patient were recorded oculographically. He was allowed to use compensatory mechanisms of body posture and movement for stabilization of vision. RESULTS: The nystagmus patient can achieve better visual performance when he is allowed to utilize complex segmental body movements for stabilization of vision. CONCLUSIONS: It is proposed that test procedures for visual performance in traffic be altered as follows: nystagmus and abnormal head postures are admittable if sufficient binocular vision is achieved. The test may use illustrations of traffic situations containing relevant details such as traffic signs. These are to be understood by the test person on triplicate presentation.

Adult↗
PubMed1997

[The low vision cyclist: handicapped orientation and assessment with the nystagmogram].

BACKGROUND: Visually impaired individuals who are unable to obtain a driving licence may use a bicycle and feel fit for traffic as part of this "bio-physical model". MATERIALS AND METHODS: Five nystagmic amblyopes who claimed to ride a bicycle were tested in respect to visual acuity, peripheral vision and oculomotor functions. In three of these cases visual acuity amounted to 0.3, in one to 0.6, in another one only to 1/35. Eye movements were recorded by electro-oculography. The following qualities of gaze were determined: Fixation-saccadic eye movements-pursuit eye movements-behaviour in light and dark-vestibulo-optokinetic movements-eye positioning in resting states and influence of mood. RESULTS: In four of the cases oculomotor regularities were found. These were explained to the patients. One of the cases was affected with a form of chaotic nystagmus. CONCLUSION: Bicycling demands on both the vestibular and the visual system. Deficiencies relevant to behaviour in traffic and the possibilities to compensate for these may be estimated based on a oculographic evaluation. This should therefore be used to advise bicyclists with a visual impairment.

Adolescent↗
PubMed1995

[Congenital nystagmus in the ophthalmologic automobile driving fitness verdict].

BACKGROUND: A driver with congenital nystagmus (CN) is supposed to have a certain minimum visual acuity and a minimum velocity of reading, with the head directed straight ahead or 10 degrees laterally. The ability to perform different oculomotor tasks depends, however, on individual properties of nystagmus and compensatory mechanisms, as is demonstrated in 4 cases. METHODS: Detailed electrooculographic (EOG) recordings were performed in 4 CN patients, in addition to the examination of visual functions. RESULTS: The visual acuity of patient 1 is sufficient (0.6 on both eyes), yet his retinal image is intermittently destabilized by a periodic alternating nystagmus. Case 2 with high myopic astigmatism and severely reduced visual acuity (right eye: finger counting; left eye: 0.2) compensates for his vertical pendular nystagmus by head nodding and for his manifest-latent horizontal nystagmus by a head turn. The optimal visual acuity of patient 3 (horizontal pendular nystagmus) is 0.3, with an oblique head position and convergence. In other head and gaze positions he has a coarse jerk nystagmus beating in the direction of gaze. Patient 4, with a high myopic astigmatism, microstrabism and manifest-latent fixational nystagmus, has a visual acuity between 0.2 and 0.3 in both eyes. He had been a licensed professional car driver, in spite of contradicting national and international criteria: but his license was refused later. CONCLUSIONS: In patients with CN, the influence of head and gaze position, monocular fixation, convergence and self or object motion on nystagmus intensity and wave forms could be important for driving, because it might influence visual acuity and motion perception. The latter hypothesis still has to be proven in further studies, performed under conditions relevant for traffic.

Adult↗
PubMed1992

[Vision disorders in children with acquired severe brain damage].

27 children with severe brain injuries were examined by an ophthalmologist and had several paediatric examinations during an eight or ten weeks' course of rehabilitation. With highly reduced levels of consciousness they had hardly any cortical visual function but frequently had brainstem controlled reactions of eyelids, pupils and eyeballs. The development of these reactions was followed up and correlated to the recovering visual functions. Some of the palpebral reflexes seemed to be of prognostic significance to the reappearance of cortical visual functions.

Adolescent↗
PubMed1991

[Temporary vision disorders, accentuated by deficient illness adjustment].

A medical expert's opinion had to be given on five patients complaining about temporary visual disturbances. 1. Haze caused by keratoconjunctivitis sicca; 2. changing refraction related to diabetes; 3. phosphenes in a paralyzed monoculus; 4. double vision with fatigue in myasthenia; 5. presumed elevation of the risk for accidents in congenital nystagmus. The loss of earning capacity in these cases should be calculated as the mean of the earning capacity during the phases of least and maximal disturbance, if it is not yet included in the loss caused by additional stationary defects. Psychological adaptation to or an additional disturbance by the disease has to be considered and may justify a higher loss of earning capacity.

Adaptation, Psychological↗
PubMed1991

[Complicated oculomotor disorders evaluated by the medical expert].

The association of sensory and motor defects may lead the medical expert to a false estimation of a patient's impairment, especially (1) if he simply adds to the sensory impairment of one eye the motor impairment of the other, without thinking of the eyes as a paired organ; (2) if he underestimates a cumulation of sensory and motor defects in the case of partial adaptation, and (3) if he judges from dyskinetic behavioral characteristics that the patient is blind. Several clinical cases illustrating these problems and allowing the following recommendations are described: (1) Prior to simply summing up the single impairments one should examine if an overlap exists. (2) In the case of cumulative disturbances with incomplete adaptation the estimated impairment should be higher. (3) To estimate an individual sensorimotor impariment that is not covered by the common recommendations, one should refer to analogous impairments, e.g. hemianopias or zones of diplopia. One should further have in mind that a patient's impairment not only depends on the objective defects, but on his personality as well. (4) Oculomotor behavioral characteristics of multiply handicapped children or of demented patients must be taken into account in order to decide whether the patient is blind or not.

Adolescent↗
PubMed1990

[100 years of the Mikulicz syndrome].

Between 1888 and 1892, Mikulicz as well as Fuchs observed each a case of oculo-salivary glandular syndrome. Ten years later, Heerfordt described uveitis complicated by swelling of the lacrimal and salivary glands. Within 100 years, the interpretation of this disease changed repeatedly and considerably: infection of particularly exposed organs--non-avirulent tuberculosis--salivotropic virus--Boeck's disease--allergic-hyperergic reaction--diencephalic and nervous dystrophy with segmental projection--(auto)immune disease--oculo-salivary complex including Sjøgren's syndrome--all these were discussed as possible aetiologies. Short biographies of Johannes von Mikulicz-Radecki, surgeon at Austrian and Prussian universities; Ernst Fuchs, ophthalmologist of Vienna; Christian Frederik Heerfordt, a Danish ophthalmologist particularly fond of publicity.

Austria↗
PubMed1987

Eye movements and vestibulo-ocular reflex in the blind.

To assess the effect of chronic deprivation of visual feedback, 21 blind patients underwent clinical and electronystagmographical examination. Patients with congenital blindness were characterized by spontaneous eye movements, inability to consciously move the eyes and absence of the vestibulo-ocular reflex (VOR), whereas eye movement abnormalities were practically absent in those with blindness acquired late in life. Active visual experience, at least in early life, seems to be crucial for the development of eye movements and VOR adjustment.

Adult↗
PubMed1985

[Dysplasia of the corneal limbus, the mesodermal iris layer and the jaw skeleton in a family].

Ten members of the family B./A. (belonging to two generations) who had dysplasia of the anterior mesodermal layer of the iris were examined. Several of them also had moderate microcornea. The shape of the skull was remarkable, with micrognathia, in some cases combined with mandibular prognathism and early loss of the teeth. Members of the older generation suffered from pannus, although only pingueculae had been present in youth and adolescence. The anomaly of the anterior part of the eye combined with "dysostosis maxillofacialis" (Peters and Hövels) may represent an abortive form of Rieger's syndrome. An aggressive pannus does not appear to have been described before in this syndrome or related diseases.

Adult↗
PubMed1984

[Right-left differences in nystagmus direction. Observations in congenital and acquired ophthalmoneurologic syndromes].

We report about 8 patients all showing a nystagmus rotatorius or giratoire and differences of the horizontal component. In syndromes of the nervous system monocular nystagmus was combined with a scew-deviation or tremor of the lids. Similar to the syndromes of the fasciculus longitudinalis posterior defects in smooth or quick movements on both sides were different. After operation of a congenital cataract a vertical nystagmus was transformed in a nystagmus latens. In congenital squint syndromes monocular vertical nystagmus may be seen if one eye or both are closed. Separate pathways from the vestibular system only lead to the vertical-moving muscles of one eye.

Adult↗
PubMed1983

[Palinopsia (visual preservation) and cerebral polyopia--clinical analysis and computed tomographic findings].

The positive visual phenomena of palinopsia and cerebral diplopia/polyopia have only rarely been recorded. The complex phenomenology (visual/oculomotor) is described based on two cases with right occipital infarcts and a review of the literature. In each case demonstrated CT revealed a small area of decreased density confined to the border region of the right area striata causing homonymous field defects. The phenomena are discussed in the light of what is known about visual after-images and hallucinations. The underlying neural mechanisms are still unknown; a defective cortical visual information processing is suggested.

Aged↗
PubMed1983

[Epidermal nevus syndrome (Schimmelpenning-Feuerstein-Mims syndrome) and early childhood cataract development].

UNLABELLED: The patient, now 14 years old, has been kept under observation since birth (and was the subject of a paper published in 1973 by Leyh and Loewel). She has cataract in both eyes, caused by intensive treatment with corticosteroids. HISTOLOGY: initially adenoma sebaceum, subsequently syringocystadenoma papilliferum. Plastic surgery was performed. With regard to visual development, the patient suffered first from deviations without fixation and now has a visual acuity of 0.25 with cataract lenses, with strabismus and nystagmus latens. Epilepsy and mental retardation have also been diagnosed.

Adenoma↗