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Biomedical subjects

J D Wirtschafter

Publications and source records attributed to J D Wirtschafter.

At least 55 records · Page 3Linked to original sources
PubMed1987

The role of medical imaging in the practice of neuro-ophthalmology.

The neuro-ophthalmologist is concerned with the myriad afflictions that can cause transient or permanent visual loss, derangement of ocular motor function, pupillary dysfunction, abnormality of lid position or function, and headache or facial pain syndrome. Once preliminary clinical evaluation has implicated dysfunction of a certain anatomic locale, the practitioner must precisely confirm or eliminate possible etiologies. This article examines pathology in six areas: orbital contents and optic nerve; cavernous sinus; chiasm; posterior visual pathway and cerebral cortex; brain stem and posterior fossa; and spinal cord. Through discussion of lesions in these areas the value of CT versus MR in making an accurate diagnosis is elucidated.

Brain Stem↗
PubMed1986

Abnormalities of the central visual pathways in Prader-Willi syndrome associated with hypopigmentation.

Patients with oculocutaneous or ocular albinism have misrouting of optic fibers, with fibers from 20 degrees or more of the temporal retina crossing at the chiasm instead of projecting to the ipsilateral hemisphere. Misrouting can result in strabismus and nystagmus. Because patients with the Prader-Willi syndrome may also have hypopigmentation and strabismus, we wondered whether they too might have misrouting of optic fibers. We therefore studied six patients with Prader-Willi syndrome selected for a history of strabismus, using pattern-onset visually evoked potentials with binocular and monocular stimulation to look for evidence of misrouted retinal-ganglion fibers. Four had hypopigmentation, and three of these four had abnormal evoked potentials indistinguishable from those recorded in human albinos. The two with normal pigmentation had normal responses. These findings indicate that patients with Prader-Willi syndrome who have hypopigmentation have a brain abnormality characterized by misrouting of retinal-ganglion fibers at the optic chiasm--a finding previously reported only in forms of albinism.

Adult↗
PubMed1986

Minimal pigment: a new type of oculocutaneous albinism.

Minimal pigment, a new type of oculocutaneous albinism (OCA), is described. At birth, affected individuals had no skin or eye pigment, and white hair and blue irides, but minimal amounts of pigment developed in the iris during the first decade of life. They had no measurable hairbulb tyrosinase activity. A characteristic and unusual pattern of parental activity was found in each of three families studied, with one parent having normal and the other parent having abnormally low tyrosinase activity. The melanocyte ultrastructure was normal and variations in premelanosomal pigmentation correlated with tyrosinase activity. This clinical and biochemical pattern has not been seen in any of the previously described types of OCA. The biochemical defect in minimal pigment OCA is unknown.

Albinism↗
PubMed1986

Tattooing of eyelids: magnetic resonance imaging artifacts.

We describe artifacts (linear densities and distortion of the shape of the globe) on Magnetic Resonance Imaging (MRI) of the brain and orbits that result from the tattooing of human eyelids with iron oxide particles. Similar artifacts are frequently seen with certain types of external eye cosmetics and dental fillings or braces that contain ferromagnetic materials. The artifacts are most likely due to the distortion of the local magnetic field by the iron oxide. The artifact was reproduced when a tattooed pig's ear was scanned. Plain x-ray films did not detect the iron oxide. These small artifacts should be recognized and not confused with abnormalities due to foreign bodies of surgical material.

Animals↗
PubMed1985

Classification of congenital and early onset retinitis pigmentosa.

We retrospectively studied 36 patients with congenital (Leber's amaurosis) and early onset retinitis pigmentosa (RP) to develop a new schematic classification system based on the age at onset of symptoms, severity of visual loss, and associated nonocular abnormalities. Our four groups were designated as complicated and uncomplicated Leber's congenital amaurosis and juvenile and early onset RP. Criteria for patient selection included an extinguished or barely recordable electroretinogram, well-documented age of onset, and comprehensive ocular and medical examinations before the age of 10 years. Among the congenitally blind, the distinguishing features were the degree of hyperopia and the presence or absence of neurologic abnormalities. Among patients with infantile or juvenile onset of retinal degeneration, the distinguishing features were the severity of visual loss and the age at onset of symptoms. The presence of nystagmus and hyperopia and the severity of central visual loss differentiated congenital from early onset RP.

Child↗
PubMed1984

Hypersensitivity to DNA-damaging agents in cultured cells from patients with Usher's syndrome and Duchenne muscular dystrophy.

Lymphoblastoid lines from nine Usher's syndrome (recessively inherited retinitis pigmentosa and congenital sensorineural deafness) patients (representing eight kindreds) and from ten Duchenne muscular dystrophy patients (representing seven kindreds) showed a small but statistically significant hypersensitivity to the lethal effects of X-rays, as measured by the cellular ability to exclude the vital dye trypan blue, when compared with lines from 26 normal control subjects. Fibroblast lines from the Usher's syndrome patients, treated with X-rays or the radiomimetic, DNA-damaging chemical N-methyl-N'-nitro-N-nitrosoguanidine, also showed a statistically significant hypersensitivity when compared to normal fibroblast lines. These findings are consistent with the possibility that defective DNA repair mechanisms may be involved in the pathogenesis of these degenerative diseases.

Adolescent↗
PubMed1984

Evaluating the usefulness in neuro-ophthalmology of visual field examinations peripheral to 30 degrees.

The value of the information obtained from Goldmann manual kinetic perimetry beyond 30 degrees was examined. Of 229 randomly selected patients in a University eye clinic who had visual fields performed for reasons other than glaucoma or ocular hypertension only 3 patients had abnormalities confined to the PVF of one or both eyes. In none of these three patients was the PVF necessary to detect disease (Graves' disease, 2 cases; retinoschisis, 1 case). The PVF was useful in determining the localization of the disorder and/or the therapeutic management in 14 patients of whom 4 of these had retinitis pigmentosa and 5 had other disorders where the PVF showed the extent of the retinal damage. For ergo-ophthalmologic purposes the PVF was useful in 45 patients; most frequently because the extent of abnormality provided a basis for warning the patient. In some cases the PVF was considered to be useful for economic disability determination or to exclude significant PVF defects in a patient with only one visually useful eye. In 77 patients the PVF of each eye was abnormal but not of ergo-ophthalmologic significance. If these data can be extrapolated to automated static perimetry, there will be a very great incremental cost for any clinically useful information obtained from the examination of the PVF. Because the cost-effectiveness of the examination must be compared with competing methods of obtaining information, it is proposed that the PVF be examined (1) whenever indicated for ergo-ophthalmologic reasons, or (2) when the CVF examination does not resolve a clinical problem for which there is a reasonably high probability that (a) additional clinically useful information will be obtained by examination of the PVF after the results of the CVF examination have been analyzed, or (b) the eye is likely to have a condition that can be detected or followed best by PVF examination.

Adenoma↗
PubMed1984

Relationship of optic neuritis to disease of the paranasal sinuses.

The relationship of paranasal sinusitis to optic neuritis remains an intriguing curiosity to both the otolaryngologist and the ophthalmologist. The literature is replete with anecdotal case reports of patients whose sinusitis appears to have caused optic neuritis. There is much speculation about the pathophysiological mechanisms which relate these two distinct disease entities. Five new cases are described which highlight distinct pathophysiologic routes through which paranasal sinus disease has caused optic neuritis. These include compressive optic neuropathy secondary to mucoceles and/or pyoceles; direct extension of sinus infection to the optic nerve from suppurative paranasal sinusitis; and, in one case, from osteomyelitis of the ethmoid and sphenoid sinuses. The usefulness of computerized axial tomography of the orbits and paranasal sinuses to evaluate optic neuritis and to elucidate in detail the pathophysiology of its relationship to disease of the paranasal sinuses is emphasized. Currently, optic neuritis is felt to be a rare complication of paranasal sinusitis. Paranasal sinus surgery is advocated in those cases where sinus suppuration is suspected, or when a compressive optic neuropathy is caused by a sinus mucocele or pyocele. Since in most cases, however, optic neuritis is self-limited, it is difficult to evaluate the results of surgery in circumstances other than those mentioned already. Continued careful evaluation, management, and documentation of this group of patients is necessary to help better define the relationship between these two disease entities.

Adult↗
PubMed1984

Comparison of manual Goldmann and automated static visual fields using the Dicon 2000 perimeter in the detection of chiasmal tumors.

We report that changes in the program (software) operating an automated perimeter (hardware) remarkably improved its ability to produce interpretable diagnostic information. A group of 11 postoperative patients with pituitary adenomas and other chiasmal tumors having stable visual field defects demonstrated by manual kinetic and suprathreshold Goldmann perimetry were re-examined with automated suprathreshold static perimetry performed by the Dicon model 2000 perimeter. During the study a program for two-zone (central and peripheral), three-level suprathreshold static perimetry became available. With optimum test administration and interpretation, the Dicon 2000 perimeter with the two-zone, three-level suprathreshold program can at least equal the performance of an experienced perimetrist using manual Goldmann kinetic and selective static perimetry in the detection of visual field defects resulting from chiasmal tumors. The two-zone, three-level suprathreshold suprathreshold program was superior to a single zone, one-level programs in examining this population.

Adenoma↗
PubMed1983

Optic nerve axons and acquired alterations in the appearance of the optic disc.

The pathophysiologic events in optic nerve axons have recently been recognized as crucial to an understanding of clinically significant acquired alterations in the ophthalmoscopic appearance of the optic disc. Stasis and related abnormalities of axonal transport appear to explain most aspects of optic nerve head swelling, including optic disc drusen and retinal cottonwool spots. Loss of axoplasm and axonal death can be invoked to interpret optic disc pallor, thinning and narrowing of rim tissue, changes in the size and outline of the optic cup, laminar dots, atrophy of the retinal nerve fiber layer, and acquired demyelination and myelination of the retinal nerve fiber layer. It is speculated that the axons may also play a role in the mechanical support of the lamina cribrosa in resisting the pressure gradient across the pars scleralis of the optic nerve head. Axons and their associated glial cells may be involved in those cases where "reversibility" of cupping of the optic disc has been reported. The structure, physiology, and experimental pathologic findings of the optic nerve head have been reviewed. Many aspects concerning the final anatomic appearance of the optic nerve head have been explained. However, many questions remain concerning the intermediate mechanisms by which increased intracranial pressure retards the various components of axonal transport in papilledema and by which increased IOP causes axonal loss in glaucoma. Investigation of the molecular biology of axonal constituents and their responses to abnormalities in their physical and chemical milieu could extend our understanding of the events that result from mechanical compression and local ischemia. Moreover, we have identified a need to further explore the role of axons in the pathophysiology of optic disc cupping.

Animals↗
PubMed1982

Glaucoma visual field analysis by computed profile of nerve fiber function in optic disc sectors.

Automated perimetry has decreased the subjective aspects of data collection, but analysis has remained largely subjective. A microcomputer permits more objective analysis by regrouping and averaging data points in the threshold static visual field according to their retinotopic projection onto the optic disc rather than according to their eccentricity from the point of fixation. The applications of the technique include (1) following glaucomatous visual field loss, (2) differentiating glaucomatous from other forms of visual loss, and (3) studying the effects of aging on the visual field. Six formulas for data analysis are described, and their relative usefulness discussed. Percent loss or gain seemed to convey the most diagnostic information to the clinician. Percent of expected sensitivity was less than the decimal visual acuity when the diagnosis was glaucoma but greater when the diagnosis was cataract. In some cases this analytic method should provide information that could favorably affect patient management.

Adolescent↗