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At least 325 records · Page 18Linked to original sources

PubMed1991

A new diffuse loss index for estimating general glaucomatous visual field depression.

Experience with a number of visual fields has shown that the algorithm used earlier for estimating general depression in glaucomatous visual fields was too conservative. A new, more sophisticated algorithm for calculating diffuse loss has been devised and the results obtained in the evaluation of 20 glaucomatous visual fields were compared with those obtained manually. The new algorithm is less restrictive, yet produces values for diffuse loss which agree well with the empirical estimates (R = 0.97, N = 14). The new diffuse loss index is also compared with the mean defect index (R = 0.77, N = 159), the 18th Bebie curve ranked value (R = 0.87, N = 159), and the previous diffuse loss index (R = 0.98, N = 105). A general discussion of various aspects of diffuse loss is included.

Algorithms↗

PubMed2002

Intraocular pressure and progression of visual field damage.

Contradicting results concerning IOP control and visual field deterioration are presented. Some of these inconsistencies may be due to the statistical method of analysis. Sixty POAG patients with a perimetric follow-up over 3 years were selected. Mean and maximum IOPs were considered during the same period. The patients were divided into two groups according to the IOP control (well controlled or poorly controlled). Visual field progression was defined as a reduction in sensitivity over the fifth percentile in more than four points. Mean IOPs were not significantly different in the group of patients with a visual field deterioration compared to the stable ones, but the percentage of patients with a visual field deterioration was significantly higher in patients with higher IOPs. This holds especially true if IOP below 16 mmHg (G) is considered the 'target pressure'. IOP reduction seems to play an essential role in visual field progression. In glaucomatous patients, a strict (<16 mmHg (G)) might be necessary.

Disease Progression↗

PubMed1983

Visual field measurements in binocularly deprived cats.

Visual fields were measured in 4 binocularly deprived cats and 2 controls. The animals were tested monocularly in the area between 60 degrees contralateral to the open eye and 105 degrees ipsilateral. No difference was found between visually deprived and control cats in response to stimuli presented in the binocular segment of the visual field from 30 degrees contra laterally to 30 degrees ipsilaterally. The stimuli placed on the 45 degrees line contralaterally elicited a lower response in binocularly deprived cats than in the controls. The results show that in binocularly deprived cats the visual field can be controlled by the retinal periphery up to 45 degrees.

Animals↗

PubMed1983

Incidence of visual field loss in 20,000 eyes and its relationship to driving performance.

Automated visual field screening of 10,000 volunteers (20,000 eyes) showed the incidence of visual field loss was 3.0% to 3.5% for persons aged 16 to 60 years but was approximately 13.0% for those older than 65 years. Approximately half of the persons with abnormal visual fields were previously unaware of any problem with peripheral vision. Follow-up results suggested that the most common causes of visual field loss were glaucoma, retinal disorders, and cataracts. Drivers with binocular visual field loss had accident and conviction rates twice as high as those with normal visual fields. Drivers with monocular visual field loss had accident and conviction rates equivalent to those of a control group. Our results have important implications for mass visual field screening to detect eye diseases and for vision-related factors in traffic safety.

Accidents, Traffic↗

PubMed1979

Quantification of visual fields for statistical analysis.

The importance of visual fields in the study of ocular vascular disorders prompted the development of a method to convert visual fields plotted on a Goldmann perimeter into a digital form so that the data could be analyzed and stored by a computer. An instrument called a scotometer was designed to measure the visual fields and the various scotomata, and a data coding form was developed to facilitate the entry of the data into the computer. After extensive testing, this method is now being used in several clinical trials. Statistics have been computed that support the reliability of the coding process.

Computers↗

PubMed1982

A clinical comparison of the Friedmann visual field analyser and tangent screen perimetry.

The central visual fields of 44 optometric patients with known or suspected field defects were measured with the Friedmann Visual Field Analyser (FVA) and a 2-m tangent screen. The clinical correlation of visual field characteristics was at least adequate in more than 90% of eyes. Statistically significant correlations were also found between the area of scotoma found on the tangent screen and (1) the number of locations with reduced sensitivity and (2) the average reduction in sensitivity of the stimulated locations as determined by the FVA.

Humans↗

PubMed2003

Vigabatrin: longterm follow-up of electrophysiology and visual field examinations.

BACKGROUND: To report the results of repeated electrophysiological and visual field examinations in patients with vigabatrin-associated visual field loss (VGB-VFL) and the relationship between these electrophysiological findings, the cumulative dose of vigabatrin and the extent of visual field loss. METHODS: Twenty-two eyes of 11 patients with VGB-VFL were studied. All patients underwent surgery for therapy-resistant epilepsy. Repeated electro-oculograms (EOGs) and flash electroretinograms (ERGs) were made and the cumulative dose of vigabatrin and the visual field loss were recorded after a period of 37-47 months. RESULTS: The visual field loss was stable in patients who had stopped vigabatrin at the time of the first examination. There was a slight increase in VFL in patients who continued vigabatrin. During the second EOG and ERG, abnormalities in scotopic and photopic a-wave latencies and in scotopic b-wave amplitude were found in more than 50% of patients. Only b-wave latency became normal, while EOG, a-wave latency, a-wave amplitude and b-wave amplitude stayed abnormal. The amount of VFL and the cumulative dose of vigabatrin were statistically correlated with the b-wave amplitude, mainly photopic, found during the first and second examinations. CONCLUSION: After 4 years, EOG, flash ERG and visual field loss had not improved in patients with VGB-VFL. The statistically significant correlation found during the first examination between the amount of VFL and the cumulative dose of vigabatrin with the (mainly photopic) b-wave amplitude remained constant.

Adult↗

PubMed1992

Visual field differences for clockwise and counterclockwise mental rotation.

Geometric line drawings were presented to normal subjects in the left visual field (LVF) or right visual field (RVF) at various degrees of rotation from a centrally presented vertical standard. The task of the subject was to indicate with a reaction time (RT) response whether the laterally presented stimulus could be rotated into the vertical standard or if it was a rotated mirror image of the standard. In Study 1, an overall right hemisphere superiority was found for RT and accuracy on match trials. Most interestingly, interactions between Visual Field and Rotation Angle for the match accuracy data and between Visual Field and Direction of Rotation (clockwise or counterclockwise) for the match RT slopes were found. These interactions suggested that clockwise rotations were more readily performed in the LVF and counterclockwise rotations in the RVF, consistent with other literature for mental rotation. The purpose of Study 2 was to replicate this finding of visual field differences for rotation direction using a design in which direction and degree of rotation were varied orthogonally. No main effect of Visual Field was found. However, significant interactions between Visual Field and Rotation Angle were found for both RT and accuracy, confirming the presence of visual field differences for rotation direction in a new sample of subjects. These differences were discussed in terms of the possibly greater relevance of medially directed stimuli and a possible hemispheric bias for rotation direction, and in terms of interhemispheric transmission factors.

Adolescent↗

PubMed1991

Association of Vistech contrast sensitivity and visual field findings in glaucoma.

Single eye visual fields and contrast sensitivity were assessed in 60 subjects, who were being followed up in a glaucoma clinic for manifest glaucoma or a suspicion of glaucoma because of raised intraocular pressure. The Fieldmaster 5000 (static/kinetic perimeter) was used for the visual fields, and a Vistech wall chart sine wave grating test was used for contrast sensitivity measurements. The subjects were divided into three groups--defect (D), suspect (S) and normal (N)--on the basis of their perimetric findings by subjective grading of 16 perimetric scoring categories for each visual field. The mean Vistech sensitivity levels were not found to be significantly different between the D, S, and N field subgroups at any of the five spatial frequencies provided on the test charts (1.5, 3, 6, 12, and 18 cycles per degree). Complex algorithms combining results from two or more spatial frequencies also failed to yield any significant differences between the groups. Diagnostic sensitivity and specificities relating Vistech contrast sensitivity findings to groups N and D never concomitantly exceeded 60%.

Adult↗

PubMed1997

Association of visual field, cup-disc ratio, and magnetic resonance imaging of optic chiasm.

OBJECTIVE: To assess the association of visual field, vertical cup-disc (VC/D) ratio, and vertical height of optic chiasm. DESIGN: Case series. SETTING: Outpatient eye clinic. PATIENTS: Eighteen patients with low, normal, or elevated intraocular pressure, with or without visual field defects. INTERVENTION: Measurement of visual field, VC/D ratio, and vertical height of optic chiasm. MAIN OUTCOME MEASURES: Association between VC/D ratio and visual field defects compared with association between vertical height of optic chiasm and visual field defects. RESULTS: Visual field defects were graded as 0, 1 to 10, and 11 to 20 (from least to most severe). Group mean VC/D ratios were 0.47 (0), 0.55 (1-10), and 0.69 (11-20) for right eyes and 0.48 (0), 0.57 (1-10), and 0.75 (11-20) for left eyes. The significance level for trend was P = .02 for right eyes and P = .006 for left eyes. Group mean chiasm heights were 3.5 (0), 2.9 (1-10), and 2.2 (11-20) mm for right eyes and 3.5 (0), 2.8 (1-10), and 2.2 (11-20) mm for left eyes. The significance level for trend was P < .001 for right eyes and P = .002 for left eyes. To assess the simultaneous effects of VC/D ratio and chiasm height on the visual field defects groups, we used ordinal logistic regression models. Models with both variables implied that chiasm height was a stronger predictor of visual field defects group than VC/D ratio (for right eyes, P = .04 [VC/D ratio], P = .001 [chiasm height]; for left eyes, P = .11 [VC/D ratio], P = .005 [chiasm height]). CONCLUSIONS: When chiasm and VC/D ratio were analyzed in the same model, chiasm height was a stronger predictor of visual field defects. In advanced visual field defects, the optic chiasm is atrophic.

Adolescent↗

PubMed1992

Visual field testing in the management of cytomegalovirus retinitis.

BACKGROUND: Sequential visual field testing is an extremely helpful adjunct to ophthalmoscopy and fundus photography in the management of cytomegalovirus (CMV) retinitis with the antiviral agents ganciclovir or foscarnet in patients with the acquired immune deficiency syndrome (AIDS). The authors studied the visual field defects found in a series of 110 patients with AIDS and CMV retinitis. METHODS: Ophthalmoscopy and fundus photography were performed on all patients. Visual field analysis was performed with either tangent screen, Goldmann kinetic, or Humphrey automated static perimetry. RESULTS: Of 166 eyes in 110 patients with CMV retinitis, visual field defects were present initially in 92 (55%) eyes of 78 (70%) patients, and ultimately in 97 (53%) eyes of 90 patients in whom follow-up was available. Stabilization of visual field defects was indicative of controlled retinitis. CONCLUSION: Sequential visual field testing will confirm ophthalmoscopic evidence of successful antiviral treatment of CMV retinitis and will corroborate very early progression of previously controlled retinitis.

AIDS-Related Opportunistic Infections↗

PubMed1996

Spatial classification of glaucomatous visual field loss.

AIMS: To develop and describe an objective classification system for the spatial patterns of visual field loss found in glaucoma. METHODS: The 560 Humphrey visual field analyser (program 24-2) records were used to train an artificial neural network (ANN). The type of network used, a Kohonen self organising feature map (SOM), was configured to organise the visual field defects into 25 classes of superior visual field loss and 25 classes of inferior visual field loss. Each group of 25 classes was arranged in a 5 by 5 map. RESULTS: The SOM successfully classified the defects on the basis of the patterns of loss. The maps show a continuum of change as one moves across them with early loss at one corner and advanced loss at the opposite corner. CONCLUSIONS: ANNs can classify visual field data on the basis of the pattern of loss. Once trained the ANN can be used to classify longitudinal visual field data which may prove valuable in monitoring visual field loss.

Glaucoma↗

PubMed2000

Use of a portable head mounted perimetry system to assess bedside visual fields.

AIM: This study was designed to test the ability of a portable computer driven, head mounted visual field testing system to perform automated perimetry on patients at their bedside and to compare these results with the "gold standard" for bedside examinations, confrontation visual fields. METHODS: The Kasha visual field system is a portable automated perimeter which utilises a virtual reality headset. 37 neurosurgery patients were examined at their bedside with a central 24 degree suprathreshold testing strategy after confrontation visual field testing. The patterns of visual field defects were categorised and compared with the results of confrontation testing. RESULTS: A total of 42 field examinations were completed on 37 patients, and the average testing time for both eyes was 4.8 minutes with the perimetry system. Each of the 11 fields (100%) classified with defects on confrontation testing was similarly categorised on head mounted perimetry. 26 out of 31 (84%) visual fields were normal on both confrontation and perimetry testing, while five out of the 31 fields (16%) which were full on confrontation had visual field defects identified by head mounted perimetry. CONCLUSION: The head mounted, automated perimetry system proved easily portable and convenient for examining neurosurgical patients at their bedside in the perioperative period. The device demonstrated equal sensitivity to confrontation visual field testing methods in detecting field defects and offers the advantage of standardised, quantifiable testing with graphic results for follow up examinations.

Adult↗

PubMed1967

Spatial and temporal summation in impaired regions of the visual field.

1. Spatial and temporal summation have been measured in perimetrically impaired regions of the visual field. Two classes of impairment have been studied: that resulting from lesions in the pre-geniculate visual pathways, and that resulting from post-geniculate lesions (optic radiation and/or striate cortex).2. Control measurements were made in the perimetrically normal visual fields of subjects without visual pathway damage.3. Spatial summation was found altered in all impaired visual fields: the greater the threshold elevation produced by the lesion, the more nearly complete was spatial summation.4. The above relation between threshold and spatial summation has also been given numerical form. This has been shown to be very nearly identical to the threshold-spatial summation relation which is seen as stimuli are increasingly peripherally presented in normal visual fields.5. It has been shown that the alterations of spatial summation brought about by a lesion are found only in those parts of the visual field which are perimetrically impaired: spatial summation is always normal in perimetrically normal regions of a visual field, even if other parts of the same field show impairment.6. Temporal summation has been found altered in visual fields impaired by post-geniculate lesions: the greater the threshold elevation produced by the lesion, the more nearly complete was temporal summation. These changes in temporal summation were found only in perimetrically impaired regions of the field.7. Temporal summation was normal in visual fields impaired by pregeniculate lesions.

Geniculate Bodies↗

PubMed2004

Visual field defects after intravitreous administration of indocyanine green in macular hole surgery.

OBJECTIVES: To report the findings on a patient cohort with visual field defects after macular hole surgery with indocyanine green (ICG)-assisted internal limiting membrane peeling and to investigate the correlation between the defects and the use of ICG. DESIGN: Retrospective, noncomparative interventional case series. PARTICIPANTS: Thirty-nine eyes of 38 patients having the clinical diagnosis of a macular hole who underwent pars plana vitrectomy between January 1, 2001, and December 31, 2002, were enrolled in this study. INTERVENTION: Indocyanine green-assisted internal limiting membrane peeling was performed on a series of 22 eyes: 12 eyes using a 0.5% ICG solution and 3-minute exposure to the retina (group 1), 4 eyes using a 0.5% ICG solution and immediate washout (group 2), and 6 eyes using a 0.25% ICG solution and immediate washout (group 3). The remaining 17 eyes underwent vitrectomy without ICG-assisted internal limiting membrane peeling (group 4). MAIN OUTCOME MEASURES: Visual field, best-corrected visual acuity, and fundus photography were evaluated. RESULTS: Postoperatively, all patients (100%) in group 1 and 1 (25%) of 4 eyes in group 2 had visual field defects. None of the patients in group 3 had a visual field defect. The visual field defects included 10 eyes (84%) with nasal defects, 1 eye (8%) with an inferotemporal defect, and 1 eye (8%) with an extensive visual field defect. Ophthalmoscopy revealed mild to moderate optic disc pallor in 8 (62%) of 13 eyes with postoperative visual field defects. Only 1 patient in group 4 had an inferotemporal defect; none of the other patients in group 4 had visual field defects. There was no statistically significant difference in postoperative visual acuity between patients with and without postoperative visual field defects. CONCLUSIONS: Although this study was limited by the few patients enrolled, our experience indicates that visual field defects, specifically nasal defects, can occur after macular hole surgery with ICG-assisted internal limiting membrane peeling, and that the incidence depends on the concentration of the ICG solution and/or the exposure time to the retina. Further studies are needed to clarify the pathomechanism of visual field defects.

Coloring Agents↗

PubMed1999

The effect of mental workload on the visual field size and shape.

Mental workload is known to reduce the area of one's visual field, but little is known about its effects on the shape of the visual field. Considering this, the visual fields of 13 subjects were measured concurrently under three levels of mental workload using a Goldmann visual perimeter. Tone counting tasks were employed to induce mental workload, avoiding interference with visual performance. Various methods of shape measurement and analysis were used to investigate the variation of the shape of the visual field as a function of mental load. As expected, the mean area of visual fields reduced to 92.2% in the medium workload condition and to 86.41% under heavy workload, compared to light load condition. This tunnelling effect was not uniform, but resulted in statistically significant shape distortion as well, as measured by the majority of the 12 shape indices used here. These results have visual performance implications in many tasks that are susceptible to changes in visual fields and peripheral vision. Knowledge of the dynamics of the visual field as a function of mental workload can offer significant advantages also in mathematical modelling of visual search.

Adult↗

PubMed1993

Functional properties of neurons in area V1 of awake macaque monkeys: peripheral versus central visual field representation.

The region of the striate cortex where the visual field is represented up to 52 degrees from the fovea was explored in awake, behaving monkeys. Extracellular recordings were made from 241 neurons. On the basis of their receptive field position in the visual field, they were subdivided into a central (within 10 degrees from the fovea) and a peripheral (beyond 10 degrees) group. Sensitivity to orientation, length, direction and velocity of movement of conventional light stimuli was tested and compared in the two samples. Besides the well-known increase of receptive field size with eccentricity, gross differences were found only for the sensitivity to the velocity of stimulus movement. The great majority of neurons in the central sample preferred slow velocities and showed no sensitivity to velocities above 100 degrees/sec. In contrast, many peripheral neurons were poorly sensitive to slow speeds of movement and well responsive to high velocities, above 100 degrees/sec. Cells that showed a better response to an actual stimulus movement in the visual field than to a retinal image movement self-induced by an eye-movement ("real-motion" cells) were also searched for in the two samples. They were found in the 13% of the central neurons and in the 25% of the peripheral neurons. Present data extend to the awake, behaving animal what already known from paralysed animal, indicating that in physiological conditions central and peripheral vision have a different functional role in the analysis of motion within the visual field.

Animals↗

PubMed1990

Evaluating human and automated interpretation of visual field data in perimetry.

The complexity of visual field result evaluation has increased with the advent of automated perimetry. This in turn makes software assistance such as provided by the new Octosmart program interesting and desirable. Its accuracy and reliability in visual field evaluation must be tested, though, and the testing methodology itself must be developed. For this purpose, 27 visual fields were evaluated by three human interpreters and the Octosmart program. Based on a newly developed compound index, the performance of the three interpreters and Octosmart is described and a high degree of consistency is demonstrated.

Diagnosis, Computer-Assisted↗