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At least 163 records · Page 9Linked to original sources
PubMed1991

[Central visual fields in pure alexia "without hemianopsia"--visual dysfunction in the right hemifield, and alexia for "kana" words in the left].

Following a left occipito-temporal subcortical hematoma, a 57-year-old, right-handed man developed pure alexia that was more prominent in kana words, especially in kana nonwords, than in kanji letters. Although a kinetic perimetry with a Goldmann perimeter showed his visual fields to be full, a static perimetry with a Humphrey visual field analyzer disclosed decreased visual sensitivity in the right visual field in its central 30 degrees. In addition, a tachnistoscopic examination with Landolt rings revealed his visual acuity (the ability of two points discrimination) to have decreased in the right half of his central visual filed in its 3 degrees. In the right central vision, he was unable to recognize the letters, pictures or colors presented by the tachistoscope. Concerning the reading, the more letters in kana words or the higher the number of strokes in kanji letters, the more difficulty he experienced in orally reading both kana and kanji. On the contrary, in the left central vision, kanji reading was not so affected by an increased number of strokes as the kana-word reading which became difficult when the number of the letters increased. CT scan showed subcortical hematoma in the left occipitotemporal region. Magnetic resonance imaging 3 months after onset revealed a localized injury in the region between the left postero-inferior temporal lobe and the infero-lateral occipital lobe, including the fusiform gyrus. None of the splenium, the lingual gyrus or the optic area were affected. The spared structures also included the angular gyrus, the Wernicke area and their subcortical white matter.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Hemorrhage↗
PubMed2001

Multifocal pupillary light response fields in normal subjects and patients with visual field defects.

The optimal conditions for recording focal pupillary light responses with a multifocal stimulation technique were determined, and the technique was applied to normal subjects and patients with visual field defects. Thirty-seven hexagonal stimuli were presented on a TV monitor with a visual field of 40 degrees diameter under a constant background illumination. Using a slow (4.7 Hz) m-sequence, reliable focal responses were obtained in both normal subjects and patients. The pupillary field and visual field were well correlated in patients with retinal diseases, but the correlation was not strong in patients with optic-nerve diseases. Pupillary light responses were reduced in the blind hemifield in patients with post-geniculate lesions. These results indicate that the multifocal stimulation technique can be used clinically to obtain a pupillary field for objective visual field testing.

Adult↗
PubMed1992

Disc and field damage in patients with unilateral visual field loss from primary open-angle glaucoma.

To assess the temporal relationship between field and disc change in early glaucoma, 24 patients with unilateral visual field loss from primary open angle glaucoma were identified for planimetric optic disc measurements. Cross-sectional analysis of disc rim area was performed and compared to 25 age-matched normal controls. The mean (+/- SD) disc rim area in eyes with normal visual fields (1.10 +/- 0.31 mm2) was slightly larger than that of eyes with visual field loss (0.90 +/- 0.33 mm2). The mean disc rim area in the control group (1.49 +/- 0.19 mm2) was significantly different from both sets of eyes in the asymmetric primary open angle glaucoma patients (p = 0.000). These findings support the hypothesis that loss of the optic disc rim can be detected before perimetric abnormalities develop in patients with glaucoma.

Aged↗
PubMed1982

Functional organization of neurons in cat striate cortex: variations in ocular dominance and receptive-field type with cortical laminae and location in visual field.

1. Binocularity and receptive-field type of cortical neurons were assessed relative to the cortical layer in which the neurons were recorded and to receptive-field position in the visual field. 2. Receptive fields were observed up to 2 degrees into the ipsilateral half of the visual field. In the region up to 2 degrees on either side of the vertical meridian, the relative contribution of the ipsilateral eye was reduced. This progression in ocular dominance from ipsilateral to contralateral visual field agrees well with the distribution of X-cells about the nasotemporal division. 3. The region of maximum binocularity in each hemifield was found to be a 12 degree wide vertical strip extending from the vertical meridian to 12 degrees contralateral. In the representation of the central 12 degree strip, most units in all cortical layers were binocular. 4. Low levels of binocularity were observed at a considerable distance before the monocular portion of the visual field was reached. 5. The decrease in binocularity for simple cells occurred closer to the vertical meridian than for complex cells. 6. The proportions of cells classified as simple or complex did not change with position in the visual field. 7. At all locations in the visual field, complex cells showed a higher percentage of binocularity than simple cells. 8. The proportions of two types of simple cells, I and II, and complex cells were variable between cortical layers. Layer IV contained predominantly simple II cells, whereas layer V contained predominantly complex cells. 9. The results are discussed in terms of visual perception and the dynamic pattern of visual stimulation around a moving animal, the optic flow field.

Animals↗
PubMedDate not supplied

Constriction of the visual field of children after early visual deprivation.

PURPOSE: We measured the extent of the monocular visual fields of children deprived of normal visual experience and examined the influence of the timing and duration of deprivation, of whether deprivation was monocular or binocular, of having patched the fellow eye, and of optical factors. METHODS: The Goldmann perimeter and a 6.4' stimulus of either 31.8 cd/m2 (target 12e) or of 318 cd/m2 (target 14e) were used to test 44 children treated for a dense and central cataract in one (n = 25) or both (n = 31) eyes that developed before 6 years of age. Then, the influence of optical factors was assessed in two adults treated for a late-onset, unilateral cataract and in two children treated for unilateral congenital cataract. RESULTS: Compared with age norms or the normal fellow eye, all children treated for cataract showed a restricted field, especially temporally, even when deprivation began as late as 6 years of age and lasted less than 6 months. The restrictions were larger than those shown by the adults who developed cataracts. The restrictions were larger after longer deprivation and monocular deprivation than after binocular deprivation. However, children who regularly patched the fellow nondeprived eye and, therefore, experienced less interocular competition, exhibited smaller restrictions temporally. Neither visual acuity nor optical factors could account for all of the restrictions in the deprived children. CONCLUSIONS: The development of the visual field is vulnerable to the effects of deprivation, especially to unilateral deprivation and to long deprivation. The losses likely reflect alterations in the visual pathways subserving peripheral vision.

Adult↗
PubMed1996

Correlation between the progression of optic disc and visual field changes in glaucoma.

Visual field test and optic disc evaluation are the standard examination techniques used to detect the onset and progression of glaucoma. This explorative study was performed to assess the temporal correlation between visual field and optic disc changes in eyes with ocular hypertension and well-established glaucoma. Eighty-six hypertensive and 16 glaucomatous eyes were followed up for a period of up to 9 years (average 4.4 yrs) using kinetic and computerized static perimetry and optic disc manual morphometry. Perimetric changes were based on a series of strict criteria and optic disc changes were based as a reduction in the baseline rim area/disc area ratio (R/D) measurement exceeding the 99% confidence interval for intraobserver reproducibility (7.7%). Optic disc changes were found prior to visual field changes in four hypertensive eyes, whereas visual field changes were found prior to disc changes in six glaucomatous eyes (p = 0.042). The results of our explorative study suggest that quantitative optic disc analysis may be more sensitive than visual field examination in detecting early glaucomatous changes, whereas visual field examination may be more sensitive than quantitative optic disc analysis in detecting glaucomatous progressions in eyes with well established glaucoma.

Aged↗
PubMed1990

Visual acuity loss in retinitis pigmentosa. Relationship to visual field loss.

We compared visual acuity with visual field radius in 235 patients with typical retinitis pigmentosa and no evidence of other visual acuity-limiting problems (such as cataract or foveal cystoid edema). Results show a strong relationship between visual acuity loss and proximity to the fovea of the visual field border (shortest distance from the foveal center to the border of the V-4-e isopter) for these patients. Ninety-six percent of patients with central visual field radii greater than 30 degrees have visual acuities of 20/40 or better; 32% of patients with central visual field radii smaller than 10 degrees have visual acuity of 20/40 or better.

Humans↗
PubMed1996

A note on the concept of the visual field in neurology, psychology, and visual neuroscience.

Some current confusions in visual neuroscience and psychology over the use of the terms 'visual field', 'field of vision', 'stimulus field', and topographic 'brain maps' are reviewed. These are often used as synonyms, whereas they refer to quite different things. A plea is made that visual scientists should use these terms correctly to avoid conceptual and engineering confusion.

Brain↗
PubMed1997

Lack of association between localized cataract and visual field loss: the Blue Mountains Eye Study.

PURPOSE: To examine whether localized cataract is related to localized field defects on suprathreshold visual field testing. METHODS: Suprathreshold screening visual fields (Humphrey 76-point test) and lens photographs, graded using the Wisconsin System, were performed on participants attending the Blue Mountains Eye Study, which examined 3654 subjects residing in an area west of Sydney, NSW, Australia. The results for 2276 subjects were analysed in the present study. RESULTS: There were no significant relationships between total points missing in the visual field and the degree of cortical, posterior subcapsular (PSC) or nuclear cataract after adjusting for confounders (test for trend P = 0.9, 0.7 and 0.9, respectively). Adjusted prevalence ratios and 95% confidence limits for the association between 10 or more points missing and the presence of cataract were 0.94 (0.77-1.25) for cortical, 1.26 (0.82-1.93) for PSC and 1.06 (0.86-1.30) for nuclear cataract. Similarly, there was no relationship between the presence of cortical or PSC cataract and sectoral visual field loss in any quadrant or hemifield. CONCLUSIONS: Neither cortical, nuclear nor PSC cataracts increase the total points missing on the 76-point suprathreshold field test. Similarly, neither cortical nor PSC cataracts cause sectoral visual field loss on this screening field test. In the presence of cataract, sectoral visual field loss on non-thresholding visual field screeners must be attributed to other causes, such as glaucoma. The present study provides a clinical alert that localized field loss is unlikely to be related to cataract.

Aged↗
PubMed1983

Does reduction of intraocular pressure (IOP) prevent visual field loss in glaucoma?

The visual fields of 54 eyes (27 patients) having a medical diagnosis of open-angle glaucoma and receiving treatment were compared with the visual fields recorded at the time of diagnosis of the disease. Visual fields remained stable in 34 (62%) of the glaucomatous eyes. However, reduction of the intraocular pressure (IOP) did not prevent the progression of existing field defects in 16 of 21 eyes nor prevent field damage from occurring in 4 of 33 eyes which had normal visual fields at the commencement of treatment. The presence of a visual field defect at the time of diagnosis was clearly associated with a high risk of continued field decay during treatment. Intraocular pressure at the time of diagnosis did not identify which eyes would develop visual field loss or suffer further loss despite hypotensive treatment. Likewise, the extent to which the IOP was reduced by treatment did not appear to be related to the decay of visual field.

Adult↗