Biomedical subjects

S G Jacobson

Publications and source records attributed to S G Jacobson.

136 records · Page 8Linked to original sources

PubMed1979

Foveal cone electroretinograms in strabismic amblyopia: comparison with juvenile macular degeneration, macular scars, and optic atrophy.

A hand-held stimulator-ophthalmoscope was used to elicit foveal cone electroretinograms (ERGs) from fifteen patients with strabismic amblyopia. The ERGs were in response to a 4 degrees stimulus visualized on the fundus and centred on the fovea throughout testing. Foveal cone ERGs from amblyopic eyes were normal in amplitude and normal in b-wave implicit time. Interocular differences in ERGs in patients with amblyopia were no greater than those in normal subjects. Patients with comparable visual acuity loss due to macular scars or juvenile hereditary macular degeneration had abnormal foveal cone ERGs, while patients with optic atrophy had normal responses. These findings support the idea that the defect in strabismic amblyopia does not involve a functional abnormality in the fovea distal to the ganglion cell layer.

Adolescent↗

PubMed1979

Development of amblyopia in infants.

New techniques have permitted serial assessments of visual acuity in infants. Acuity measurements in infants with astigmatism did not reveal meridional amblyopia during the first year of life. Measurements in infants with esotropia showed marked differences in acuity of the two eyes as early as the first 6 months of life. Therapeutic occlusion of the non-deviating eye improves the acuity of the deviating eye but at the expense of the occluded eye. After discontinuing occlusion, rapid increases in acuity of the formerly occluded eye can occur.

Aging↗

PubMed1977

Pathological changes in the optic chiasm of the cat following local injection of diphtheria toxin.

The optic chiasm in 14 cats was injected stereotactically with small amounts of diphtheria toxin and the morphological changes were examined by light and electron microscopy. Phagocytosis was already well-marked at 3 hr after injection and massive at 1 week. Intercellular oedema was extensive in the first week and, though diminished, was still present after 1 month. The oedema was most marked in the subendothelial regions in the early stages but was found among the nerve fibres and glial processes in those animals which survived for longer periods. Demyelination and Wallerian-type degeneration were established at 3 hr after injection and both processes continued up to 2 months and beyond. Scarring and an absolute loss of nerve fibres were present in the longer-surviving animals. Unequivocal evidence of remyelination was not obtained.

Animals↗

PubMed1977

Nasal field loss in cats reared with convergent squint: behavioural studies.

1. The extent of the monocular visual field in cats reared with convergent squint in one eye was determined by a behavioural perimetry technique. 2. Significant reduction in the extent of the visual field was found in the squinting eyes. 3. The visual field defect is a graded one, located mainly in the nasal field, but in some cats extending into the temporal visual field. The defect includes a zone of absolute loss of response to stimuli at the extreme nasal field, adjacent areas of partial response and areas of 100% response in the periphery of the temporal field. 4. A direct relationship was found between the angle of horizontal deviation of the squinting eye and the amount of visual field loss: i.e. the larger the angle of squint, the greater the loss of nasal field. 5. It is suggested that the process leading to a loss in nasal visual field is independent of the loss of visual acuity in squinting cats, since the latter is not related to the angle of squint. 6. The significant loss in nasal visual field found by behavioural experiments in cats reared with a convergent squint thus correlates with comparable deficits found in the physiology and morphology of the lateral geniculate nucleus (Ikeda, Plant & Tremain, 1977), although the behaviourally determined loss of nasal field is greater than would be expected from the study of the response of the LGN neurones.

Animals↗

PubMed1977