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Biomedical subjects

R E Carr

Publications and source records attributed to R E Carr.

At least 73 records · Page 4Linked to original sources
PubMed1983

Pigmented paravenous chorioretinal atrophy.

Six patients (three men and three women, ranging in age from 19 to 65 years) with pigmented paravenous chorioretinal atrophy, a rare disorder of unknown origin, were studied for three- to 21-year periods. The diagnosis was made on the basis of the distinctive fundus appearance of bilateral, symmetrical bone corpuscular pigment accumulation exclusively along the distribution of the retinal veins. Although the fundus abnormalities can be mild or severe, retinal function tests indicated that this is a geographic and not a generalized disorder. Central visual acuities were normal. Follow-up studies showed no evidence of ophthalmoscopic or functional deterioration in five of the patients. In the sixth (Patient 6, the most severely affected), there was a mild progression of the fundus abnormality during the 21-year follow-up period.

Adult↗
PubMed1983

The visual-evoked potential in tobacco-alcohol and nutritional amblyopia.

Twelve subjects, nine with tobacco-alcohol amblyopia and three with nutritional amblyopia, were studied with pattern and flash visual-evoked potentials. We found abnormal steady-state responses in all 12 patients, including those with minor visual abnormalities, when the contrast of the stimulus was decreased. The latency of the first major positive wave (P100) of the flash- or pattern-evoked potential was not delayed in 11 of the 12 patients. The normal P100 latencies differed from the prolonged latencies found in other patients with loss of central nervous system myelin caused by vitamin B12 deficiency or multiple sclerosis.

Alcoholism↗
PubMed1983

The pattern electroretinogram in optic nerve disease.

Pattern evoked electroretinograms (PERG), diffuse flash electroretinograms (ERG) and visual evoked potentials were studied in patients with unilateral optic nerve disease. Patients with Snellen acuities of less than 6/30 did not have recordable PERGs in their affected eye, whereas their diffuse flash ERGs were normal. The VEPs were correspondingly reduced or absent when recorded from the poorer seeing eyes. A second group of patients with Snellen acuity between 6/6 and 6/30 in the involved eye showed reductions in the mean PERG amplitude of the affected as compared with the normal eyes. All affected eyes showed an abnormal contrast threshold measured with the PERG amplitude. Such results underscore the diagnostic value of the PERG in detecting even mildly affected cases of optic nerve disease.

Adult↗
PubMed1983

The 20/20 eye in multiple sclerosis.

Using clinical and electrophysiologic measures, we evaluated the visual pathway of patients who had multiple sclerosis, 20/20 Snellen acuity, and no history of optic neuritis. Delayed latencies were found in the transient visual evoked potentials (VEPs) of 38% of the patients, and interocular latency differences were abnormal in 67%. Contrast VEPs were abnormal in 46%. Psychophysical determinations of contrast sensitivity were abnormal in 78%. Only 17% of the patients had dyschromatopsia, 36% had afferent pupillary abnormalities, and 59% had optic nerve pallor or nerve fiber layer loss. Psychophysical contrast evaluations and VEP studies were superior to other clinical evaluations in demonstrating visual dysfunction in these patients.

Evoked Potentials, Visual↗
PubMed1982

Subtle disturbances of vision with compressive lesions of the anterior visual pathway measured by contrast sensitivity.

Contrast thresholds were determined for patients with compressive lesions of the chiasm or optic nerve but whose visual acuity was 20/20 on the Snellen scale. A generalized loss of contrast sensitivity for spatial frequencies ranging from 0.2 to 6.4 cycles per degree was found even in patients with normal color vision and full visual fields. After surgery was performed, improvements in the fields and color vision were seen in those patients who also showed a significant increase in their postoperative contrast sensitivity scores. Contrast sensitivity is shown to be a useful procedure for evaluating very mild visual complaints as well as for establishing early diagnosis and evaluation of surgical therapy in patients with compressive lesions of the anterior visual pathway.

Adult↗
PubMed1981

Visual evoked potentials in chiasmal gliomas in four adults.

Visual evoked potentials (VEPs) were recorded from four patients with surgically verified chiasmal gliomas. Despite good visual acuity, 6/12(20/40) or better in each eye, these patients showed substantially reduced VEP amplitudes to a diffuse flash stimulus and hardly detectable responses to a highly textured checkerboard-pattern stimulus. The dissociation between evoked electrical activity and visual acuity is noteworthy; this differs from previously reported findings in patients with extrinsic compressing lesions of the chiasm or with lesions of demyelinating disease, which usually reduce VEP amplitude and increase conduction time in rough proportion to a loss of visual acuity.

Adult↗
PubMed1981

Reduced contrast sensitivity in compressive lesions of the anterior visual pathway.

A clinical procedure for determining contrast sensitivity was performed on patients with suspected sella area masses. The test consisted of a series of six plates, each containing a bar pattern of fixed sinusoidal spatial frequency in which contrast varies along the length of the bar. Patients with compressive lesions of the chiasm of optic nerve showed loss of contrast sensitivity over the whole range of spatial frequencies. The general loss in contrast was evident even in patients with 20/20 Snellen acuity. After surgery, contrast sensitivity improved, as did other measures of vision, but significant contrast deficits remained. Contrast sensitivity is a sensitive indicator for the diagnosis and evaluation of compressive lesions of the chiasm.

Adult↗