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At least 1,765 records · Page 98Linked to original sources
PubMed1987

Relation of visual field defects to neuropsychological outcome after closed head injury.

Neuropsychological outcome within two years after injury was determined in 159 head injured patients who were classified into three groups according to the presence of either unilateral, bilateral, or no visual field defects (VFDs). The VFDs occurred irrespective of injury severity as determined by the Glasgow coma scale, or social outcome as determined by the Glasgow outcome scale. Differences among the three visual field groups were obtained for several neuropsychological functions: intelligence, memory, learning, acquired verbal skills, visuospatial skills, and visuomotor speed. Patients with bilateral VFDs were more severely impaired neuropsychologically than those with unilateral or no VFDs. Occurrences of secondary complications (brain swelling, intracranial hypertension, and hyperemia) were more prevalent among the bilateral VFD cases. The findings suggested that bilateral VFDs may be indicators of increased brain damage from secondary insults.

Adult↗
PubMed1991

Detection of chromatic deviations from white across the human visual field.

We studied how much blue, green, or red light had to be added to or subtracted from white to obtain veridical hue perception (blue, green, red, or their complementary colours) at various locations in the temporal visual field. The CIE 1931 (x, y) chromaticity coordinates corresponding to a veridical hue perception were subtracted from the chromaticity coordinates of the white (0.35, 0.35) in order to obtain the threshold differences (dx, dy) in chromaticity coordinates. When stimulus size was constant at all visual field locations, dx and dy changed with eccentricity. However, when the stimulus was M-scaled by magnifying its size with increasing eccentricity in inverse proportion to the lowest local sampling density across the human retina (cones and ganglion cells at eccentricities 0-10 and above 10 deg, respectively), dx and dy remained constant at all eccentricities.

Adult↗
PubMed1981

Optic disc and visual field changes in primary open angle glaucoma.

Rapid and accurate detection of glaucomatous damage at its onset or on its progression is desirable for optimum patient management. Tonometry alone is insufficient in ensuring adequacy of therapy; also required are stereoscopic optic disc review and quantitative perimetry. Signs of early optic nerve head damage from primary open angle glaucoma (POAG) include nerve fibre layer haemorrhage, a generalised increase in optic cup size and a localised increase in optic cup size. The latter two are absolute indications for initiation or acceleration of ocular hypotensive therapy. Accurate perimetric plotting of the normal blind spot, careful examination for a nasal step, and a thorough search of the paracentral area of the visual field are recommended for detection of the earliest visual field changes in POAG. Paracentral scotomata, nasal steps and repeated asymmetric concentric contraction of the isopters are three early, specific signs of nerve fibre bundle damage.

Eye Diseases↗
PubMed1985

Correlation of visual field, treatment fields, and dose in helium ion irradiation of uveal melanoma.

We correlated predicted radiation distributions in 29 patients with uveal melanoma (treated with 5,000 to 8,000 rads of helium ion therapy) with fundus photography and visual field deficits. The tumor was entirely within the treatment region in all patients. The fraction of the predicted high-dose and low-dose regions corresponding with an absolute scotoma was fitted by a linear regression model (r2 = .721) with three independent variables: dose region, initial condition, and time since therapy. The defect in the maximum-dose region increased at an average rate of 0.270/year. This differed (P = .002) from the rate in the penumbra region: (0.104/year). The rate in the penumbra differed (P = .01) from that in the predicted low-dose region, where scotoma did not increase with time. The pattern and time course of visual field loss in the different radiation dose regions tended to support the conclusion that isodose calculations are accurate. The data were consistent with the hypothesis that visual loss secondary to irradiation results primarily from radiation vasculopathy and not from direct damage to photoreceptors or ganglion cells. Development of an absolute scotoma may require a dose in excess of 5,000 rads.

Helium↗
PubMed1993

Bilateral visual field processing and evoked potential interhemispheric transmission time.

The relationship between the efficiency of interhemispheric interactions via the corpus callosum and the speed and accuracy in making comparisons of information simultaneously presented to the right and left visual fields was studied by comparing bilateral (vs unilateral) advantages in matching letters, with evoked potential measures of interhemispheric transmission time (EP-IHTT). The primary finding was a strong correlation suggesting that larger bilateral field advantages in reaction time are associated with faster EP-IHTT. However, the association between EP-IHTT and bilateral advantage was strong only for transmission speed from left hemisphere to right hemisphere, but not for speed of transmission in the opposite direction. The data are consistent with a hypothesis of asymmetric homologue enhancement, i.e. a directionally asymmetric callosal influence which facilitates processing of letter stimuli in the right hemisphere allowing for increased response speed and accuracy of bilateral visual field comparisons.

Adolescent↗
PubMed1986

Multi-flash campimetry as an indicator of visual field loss in glaucoma.

Multi-flash campimetry is a computer-implemented technique used for the rapid assessment of temporal resolving power across the visual field. On the basis of previous reports that glaucoma patients exhibit impaired temporal sensitivity earlier than conventional perimetric field loss, the question of whether multi-flash campimetry might also be sensitive to the visual consequences of glaucoma was explored. Of the 27 patients that were tested, only one had normal temporal resolving power in both eyes, suggesting that multi-flash campimetry might be a useful aid in determining whether a patient should be diagnosed and treated as a glaucoma suspect or as a confirmed glaucoma patient.

Adult↗
PubMed1994

[Influence of refraction on the visual field defects in normal tension glaucoma and primary open angle glaucoma eyes].

The prevalence of normal tension glaucoma (NTG) or primary open angle glaucoma (POAG) is higher in myopic populations and the prevalence of myopia and NTG is relatively high in the Japanese. To evaluate the influence of myopic refractive error on the central visual field defect in NTG eyes, the data obtained from NTG eyes with the Humphrey Visual Field Analyser were analysed in comparison with those from POAG eyes. One hundred and twenty NTG eyes and one hundred and ninety-seven POAG eyes were included. All of them had clear ocular media, but no myopic degeneration in the fundus. Multiple linear regression analysis was performed with a dependent variable of the deviation of the measured threshold value from normal reference value (total deviation, STATPAC) and independent variables of refractive error and mean deviation (STATPAC). Myopic power was found to be positively correlated with the depression in the lower papillo-macular area in both NTG and POAG eyes, and it was negatively correlated with the depression in an upper arcuate area extending just nasal to the fixation only in NTG eyes.

Adult↗
PubMed2005

Orientation discrimination across the visual field: size estimates near contrast threshold.

Performance in detection and discrimination tasks can often be made equal across the visual field through appropriate stimulus scaling. The parameter E2 is used to characterize the rate at which stimulus dimensions (e.g., size or contrast) must increase in order to achieve foveal levels of performance. We calculated both size and contrast E2 values for orientation discrimination using a spatial scaling procedure that involves measuring combination size and contrast thresholds for stimuli with constant size-to-contrast ratios. E2 values for size scaling were 5.77 degrees and 5.92 degrees. These values are three to four times larger than those recovered previously using similar stimuli at contrasts well above detection threshold (Sally & Gurnsey, 2003). E2 values for contrast scaling were 324.2 degrees and 44.3 degrees, indicating that for large stimuli little contrast scaling (.3% to 2.3% increase) was required in order to equate performance in the fovea and the largest eccentricity (10 degrees). A similar pattern of results was found using a spatial scaling method that involves measuring contrast thresholds for target identification as a function of size across eccentricities. We conclude that the size scaling for orientation discrimination at near-threshold stimulus contrasts is much larger than that required at suprathreshold contrasts. This may arise, at least in part, from contrast-dependent changes in mechanisms that subserve task performance.

Differential Threshold↗
PubMed1985

Critical fusion frequency in the central visual field.

The critical fusion frequency (CFF) was measured across the central visual field. Stimulus parameters were adjusted to ensure an increase in CFF at the fovea. Comparison was made between the foveal and extra-foveal CFF values. The study showed that, while the CFF may be highest at the fovea when the CFF values are generally low, stimulus parameter changes that increase the CFF result in a greater increase extra-foveally. Ultimately, then, the CFF maximum shifts from the fovea to an extra-foveal area. Under the experimental conditions used in the study, the maximum occurred approximately 10 degrees from fixation.

Flicker Fusion↗
PubMed1994

Directional anisotropy of motion sensitivity across the visual field.

There is an implicit assumption in most models of movement direction perception that sensitivity to motion is directionally isotropic, i.e. equal for movement in all directions. However, most previous research on directional effects on human motion perception have measured responses (e.g. manual reaction times) to suprathreshold stimuli rather than motion sensitivity. I investigated this possibility by measuring monocular sensitivity to motion coherence in small field random-dot kinematograms with global leftwards or rightwards motion as a function of eccentricity along the horizontal meridian in each eye of six observers. Although foveal motion sensitivity was isotropic, small but significant differences (about 0.1 log units) in sensitivity in favour of centripetal motion were observed at eccentricities between 5.0 and 12.5 deg. Motion anisotropy was significantly larger in the temporal than the nasal visual hemifield. In a second experiment, motion coherence thresholds for upwards and downwards movement were measured foveally and at +/- 5 deg on the vertical meridian. At the fovea, no difference in sensitivity to upwards vs downwards motion was observed but these vertical axis thresholds were significantly higher than foveal thresholds for movement along the horizontal axis. Directional anisotropy in favour of centripetal motion was present in the inferior visual field but directional isotropy was found for the superior visual field. Perhaps this generally heightened sensitivity to centripetal directions may function normally to facilitate figure/ground segmentation in the presence of centrifugally-moving background contours that typically accompany forward locomotion.

Adolescent↗
PubMed1986

Visual field area response to increased target intensity: a method of detecting ocular disease.

Application of computer digitizing methods to conventional kinetic visual field test data permits mathematical analysis of these data. In some cases this provides more information than is available by a simple inspection of the field charts. This is demonstrated by analysis of multiple isopter data for a patient with open-angle glaucoma and a patient with retinitis pigmentosa.

Adult↗
PubMed1980

Visual field decay in normal subjects and in cases of chronic glaucoma.

Visual field information obtained with the automatic Computer-Perimeter ('Competer') can be condensed into a single numerical value. This performance measure was applied to a normal population to determine the physiologic decay of retinal sensitivity with aging. Further, the development of this performance measure was followed in 54 glaucoma eyes which were divided into three groups: Untreated, treated with satisfactory intraocular pressure (IOP) regulation, and treated with satisfactory IOP regulation. All eyes were examined perimetrically on at least three separate occasions. Decaying performance measures were found in the preponderance of glaucoma eyes. Therapy aimed at lowering the IOP did not offer a protective effect. Papillary hemorrhage and a significant decay in performance are usually found in the same eye.

Aged↗
PubMed1982

Risk factors for progression of visual field defects in medically treated patients with glaucoma.

A multivariate discriminant analysis of potential risk factors for the progression of visual field defects was performed in 70 patients with chronic open-angle or low-tension glaucoma. Male sex, low diastolic blood pressure and diabetes mellitus were found to be significant risk factors. When the patients with low-tension glaucoma were excluded, a high mean intraocular pressure was identified as a risk factor. It was concluded that there is no reliable way to predict future visual field loss in patients with glaucoma.

Blood Pressure↗
PubMed2005

The visual field in toxoplasmic retinochoroiditis.

AIMS: To document loss of central field in patients with scars from toxoplasmic retinochoroiditis close to the disc after resolution of disease. METHODS: Patients with a clinical diagnosis of toxoplasmic retinochoroiditis were enrolled from four centres. Automated central visual field testing was performed when their disease had settled and retinal photographs of the lesions were taken. The type of central field defect (whether absolute or relative) and whether it broke out to the periphery were correlated with the size of the retinochoroidal scar and its proximity to the optic nerve head. RESULTS: 69 eyes were enrolled; 16 (26%) were discarded because of poor field performance. Of the 53 remaining eyes, 31 showed absolute defects and 20 relative defects. Scars within one disc diameter of the disc were more likely to be associated with absolute defects breaking out to the periphery. CONCLUSION: The scarring induced by toxoplasmic retinochoroiditis is associated with considerable field loss when it occurs close to the optic nerve head. Current treatment is unlikely to ameliorate this situation. The degree of visual field loss should be an outcome measure for future trials of the efficacy of treatment trials for the disease.

Adolescent↗
PubMed1993

[Changes in optic disc rim color with glaucomatous visual field damage--a quantitative study on pattern of color changes].

We developed a new computerized method for measuring the color of the optic disc directly with objective reproductivity. We compared the optic disc color with sensitivity loss in visual fields corresponding to the disc area measured by Humphrey Field Analyzer. 11 normal eyes, 40 glaucomatous eyes, and 27 eyes with ocular hypertension were studied. In the temporal segment of the disc rim, with the exception of the area, a significant correlation between rim color and sensitivity loss was detected. In the nasal rim and macular area, however, the correlation was less significant in early stage glaucoma. Compared with normal discs, glaucomatous discs showed significant decrease in the red color element of the rim area, and some discs with ocular hypertension showed a decrease without any visual field defect.

Aged↗
PubMed1975

The effect of yttrium-90 implantation on endocrine function and visual fields in patients with "functionless" pituitary tumors, with biopsy and radiological findings.

Thirty patients with symptoms from "functionless" pituitary tumours were treated by yttrium-90 implants, and we report here the effects on symptoms, pituitary function and visual fields. On biopsy, about a third of the tumours showed some hormone granules. In the sixteen fully assessed at 1 year, pituitary function was improved in 25%, unchanged in 62-5%, and reduced in 12-5%. Improvement was confined to those in whom gonadotrophin secretion was the only function impaired pre-implant. Visual field defects were present pre-implant in ten patients (twenty eyes); at 1 year post-implant these defects had lessened in 80% and deteriorated in only 5% of eyes. Subsequently, within 5 years of the implant the field defects had worsened or recurred in four patients, all with initially extensive suprasellar projection; further treatment was then given. Remineralization of the sella was seen after implantation in seven cases, with reduction in fossa size in five. Thus pituitary implantation appears to be a practicable and reasonably simple procedure suitable for the treatment of most cases of "functionless" pituitary tumour. The "supressive" doses of irradiation used are adequate to shrink most tumours without loss of pituitary function.

Adenoma↗
PubMed1998

Occipital lobe vascular malformations: prevalence of visual field deficits and prognosis after therapeutic intervention.

BACKGROUND: The prevalence of visual field (VF) deficits in association with vascular malformations of the occipital lobe is not known, and the prognosis of the VF after therapeutic intervention has not been systematically documented. METHODS: We reviewed the clinical records of 23 consecutive patients who were managed at a single institution during a 3-year period with intracranial vascular malformations extending within the anatomic borders of the occipital lobe. Lesion location and treatment rendered were correlated with formal VF testing performed before and after therapeutic intervention. RESULTS: Twenty-one of the 23 patients underwent treatment of their lesions. Treatment included resection after preoperative embolization (12 patients), resection alone (2 patients with arteriovenous malformations and 3 patients with cavernous malformations), and stereotactic radiosurgery (4 patients; preceded by embolization in 3 of the 4). One patient was followed expectantly, and another died as a result of hemorrhage soon after undergoing endovascular embolization. The VFs were assessed before and after therapeutic intervention (follow-up assessment, 2-29 mo). New VF deficits or worsening of preexisting VF deficits were documented in 5 of the 21 treated patients (24%), but only 2 of these patients (9.5%) had persistent deficits at the time of their follow-up examinations. Among the 10 patients with pretreatment VF deficits, 5 improved and the other 5 were unchanged after treatment. CONCLUSION: Patients with occipital lobe vascular malformations frequently present with associated VF deficits. Surgical resection or stereotactic radiosurgery (with or without previous embolization) of these lesions can be performed with little risk of causing new VF deficits or worsening of preexisting ones. Many VF deficits can be expected to improve or resolve after therapy.

Adult↗