[Visual field changes in mesopic and scotopic conditions using Friedmann visual field analyser. I. Normal values].
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Acquired blepharoptosis has been associated with loss of the superior visual field (SVF) in primary gaze. Because many patients with acquired blepharoptosis complained of difficulty reading or performing other visual functions in reading gaze, a prospective study was undertaken to determine if acquired blepharoptosis was the cause of these visual dysfunctions. Preoperative and postoperative SVFs were tested in primary gaze and reading gaze in 19 patients with unilateral or bilateral acquired blepharoptosis totaling 30 eyes. Preoperative testing revealed a marked loss of the SVF in both primary gaze and reading gaze. All patients underwent levator aponeurosis defect repair. Postoperative results showed a significant improvement in both primary and reading gaze SVFs. Therefore, patients with good visual acuity complaining of difficulty reading or carrying out other visual functions in reading gaze should be examined for the presence of acquired blepharoptosis. Blepharoptosis repair can be expected to improve the SVF in both primary gaze and reading gaze.
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Visually evoked cortical potentials were studied in six patients with a homonymous and six with a bitemporal hemianopia by presenting a pattern-reversal stimulus separately to a temporal or nasal retinal area and by recording the responses from leads over the hemispheres. Homonymous visual field defects are characterized by a reduction of VECPs from the affected hemisphere. The disturbance of VECPs in bitemporal hemianopia is more serious, since the fibres from both retinal halves may be damaged by a chiasm tumour.
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A transient episode of bilateral amaurosis fugax, or transient visual loss, occurred in a patient with ophthalmic migraine associated with mitral valve prolapse while computerized visual field testing was performed. This fortunate finding illustrated characteristic defects which are compared with the patient's visual field tested 24 hours later. Statistical analysis of both examinations is stressed here.
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)
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.
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In the typical visual laterality experiment, words and letters are more rapidly and accurately identified in the right visual field than in the left. However, while such studies usually control fixation, the deployment of visual attention is rarely restricted. The present studies investigated the influence of visual attention on the visual field asymmetries normally observed in single-letter identification and lexical decision tasks. Attention was controlled using a peripheral cue that provided advance knowledge of the location of the forthcoming stimulus. The time period between the onset of the cue and the onset of the stimulus (Stimulus Onset Asynchrony--SOA) was varied, such that the time available for attention to focus upon the location was controlled. At short SOAs a right visual field advantage for identifying single letters and for making lexical decisions was apparent. However, at longer SOAs letters and words presented in the two visual fields were identified equally well. It is concluded that visual field advantages arise from an interaction of attentional and structural factors and that the attentional component in visual field asymmetries must be controlled in order to approximate more closely a true assessment of the relative functional capabilities of the right and left cerebral hemispheres.
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The 4-m confrontation visual field test has been successfully used at the Mayo Clinic for many years in addition to the standard 0.5-m confrontation visual field test. The 4-m confrontation visual field test is a test of macular function and can identify small central or paracentral scotomas that the examiner may not find when the patient is tested only at 0.5 m. Also, macular sparing in homonymous hemianopias and quadrantanopias may be identified with the 4-m confrontation visual field test. We recommend use of this confrontation visual field test, in addition to the standard 0.5-m confrontation visual field test, on appropriately selected patients to obtain the most information possible by confrontation visual field tests.
The concept of visual field enhancement is to increase the effect of the patient's habitual scanning skills by displacing peripheral images toward the residual field and mid-line. This reduces the extent of ocular and head rotation by patients with severely restricted and hemianopic visual fields. High power fresnel press-on prisms are used to effect the image displacement. This paper describes a technique that we believe to be less empirical and more reproducible than previously described in the literature.
One of the major benefits of pseudophakia is to maintain a good visual field. Visual field was therefore studied in 40 pseudophakic eyes using: 1. kinetic perimetry according to Goldmann using 3 tests: I1, I2, I4; 2. Automated perimetry. Insertion of a posterior chamber intraocular lens was performed in 85% of cases whereas the remaining 15% received an anterior chamber intraocular lens. Visual acuity was > 5/10 P2-P4 in all patients. The results showed a 15% reduction in the visual field compared to normal values. This reduction was concentric and harmonious but was more marked in internal isopters. This reduction was less marked with posterior chamber intraocular lenses. On the other hand, automated perimetry showed that global retinal sensitivity was decreased in pseudophakia, and this deficiency was more pronounced in the periphery.
The authors evaluated the influence of aging on the normal visual field sensitivity and the color visual field sensitivity. The central 5 degrees visual field of 259 normal subjects (ages 10 to 79) was evaluated with Program Macula of the Humphrey Field Analyzer. Visual field sensitivity remained constant, irrespective of age, until 40 years. In contrast, sensitivity decreased linearly with aging after 40 years. The age-related decline of visual field sensitivity was most remarkable using a blue target. Visual field sensitivity gradually decreased toward the peripheral retina measured by white, red and green targets. However, using a blue target, at 1 degree-2 degrees locations from the fovea, sensitivity was the same as foveal sensitivity. There were no statistically significant differences of visual field sensitivity between the lower half of visual field and the upper half, and between the temporal half and the nasal half. At all test locations, the ordering of visual field sensitivity was white > red > blue > green target.