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PubMed1984

The detection of motion in the peripheral visual field.

To assess the sensitivity of the periphery to motion, we measured differential motion detection and velocity discrimination as a function of eccentricity in the lower visual field. The differential motion threshold, a measure of the ability to detect relative motion (shear) between adjacent visual stimuli, is smaller than the minimum angle of resolution at all retinal loci tested. The target size required to produce the lowest differential motion threshold is surprisingly large, ranging from 1 deg in the fovea to about 20 deg at 40 degrees eccentricity. When the peripheral thresholds for differential motion and for resolution are normalized against the fovea and plotted on linear axes, the eccentricity functions are linear. Velocity discrimination (delta V/V) is as precise in the periphery as it is in the fovea, amounting to about 6% for the optimum velocity range. In the fovea, the minimum Weber fraction is reached at velocities of 5 deg/sec or faster. In the periphery this minimum is found for a faster range of velocities (greater than 30 deg/sec at 40 degrees eccentricity). If target velocity is expressed in the resolution units/second appropriate to each tested eccentricity, the velocity discrimination functions coincide. Thus, while the spatial determinants of velocity discrimination follow the change in resolution found with eccentricity, peripheral temporal sensitivity must be nearly equal to foveal temporal sensitivity.

Fovea Centralis↗
PubMed2004

Visual field loss from primary angle-closure glaucoma: a comparative study of symptomatic and asymptomatic disease.

PURPOSE: To assess the degree of visual field (VF) loss in subjects diagnosed with primary angle-closure glaucoma (PACG), and to compare the severity of such loss between those with symptomatic and asymptomatic disease. DESIGN: Observational case series. PARTICIPANTS: Seventy-six consecutive subjects with PACG who presented at a Singapore hospital. METHODS: Primary angle-closure glaucoma was defined as the presence of glaucomatous optic neuropathy and compatible VF loss associated with closed angles. There were 2 groups of subjects studied: group A consisted of those who presented with acute symptomatic angle closure, and group B consisted of those who were asymptomatic. Subjects underwent static automated threshold perimetry, and the first reliable VF was analyzed using the Advanced Glaucoma Intervention Study (AGIS) scoring system. The field tests were graded according to severity as mild, moderate, severe, and end-stage VF defects, based on AGIS scores of 0 to 5, 6 to 11, 12 to 17, and 18 to 20 respectively. MAIN OUTCOME MEASURES: Advanced Glaucoma Intervention Study scores of the first reliable threshold VF test. RESULTS: The mean age of study subjects was 61.4+/-9.6 years (range: 33-84), and the majority of subjects were female (59%) and Chinese (91%). In group A (n = 40), most eyes had mild or moderate VF defects (23 eyes [57.5%]), whereas 7 eyes (17.5%) had end-stage defects. This was in contrast to group B (n = 36), in which the majority of eyes had end-stage VF loss (19 eyes [52.8%]), with only 5 eyes (13.7%) having mild VF defects. Mean AGIS scores were 9.1+/-7.6 for group A and 14.2+/-6.9 for group B (P = 0.004). Cup-to-disc ratio was a significant predictor for VF loss, but age, gender, and level of presenting intraocular pressure were not correlated with VF outcome. CONCLUSIONS: Eyes with asymptomatic PACG often present with severe to end-stage VF loss at the time of first presentation to hospital. In contrast, most PACG eyes with previous symptomatic angle closure present with mild or moderate VF defects. The visual morbidity of PACG may be related to the finding that the asymptomatic form of the disease is visually destructive.

Acute Disease↗
PubMed1985

[Differential light perception threshold of the visual field and ERG following operatively attached retinal detachment].

After surgical treatment of retinal detachment with a spontaneously pigmented demarcation line the visual fields of twelve patients were tested. The increment threshold of all positions (determined with the Octopus automatic perimeter system) was compared with the reduction in the scotopic and photopic ERG amplitudes (determinated with the CEMIDA system). This reduction in the ERG amplitudes was evaluated using the difference between the amplitude of the ERG waves of the eye with cured retinal detachment and of the healthy fellow eye. No great correlation between the two parameters was found, but it appeared that a reduced mean increment threshold correlated with a reduction in the a-wave amplitude.

Adolescent↗
PubMedDate not supplied

Topographic mapping of glaucomatous visual field defects to scanning laser polarimetry of the peripapillary nerve fiber layer.

BACKGROUND AND OBJECTIVE: To map retinal sensitivity values within glaucomatous visual field defects (VFD) to corresponding values of scanning laser polarimetry (SLP) of the peripapillary retinal nerve fiber layer using the Wirtschafter disc sector classification. METHODS: Eyes with glaucomatous VFD (N = 28) underwent SLP and Humphrey automated perimetry. The Wirtschafter disc sector classification was used to obtain SLP values corresponding to VFD. The average and modulated SLP values were calculated and correlated with VFD. RESULTS: No significant correlation was found between retinal sensitivity and the Wirtschafter disc sector SLP values, using average values (P =.904) or modulated values (P =.409). CONCLUSION: Despite use of modulation parameters customized to correspond with the Wirtschafter disc sector classification, topographic mapping of retinal sensitivity levels within glaucomatous VFD to corresponding SLP values was not possible in this group of glaucomatous eyes.

Aged↗
PubMed2004

Reduction of left visual field lexical decision accuracy as a result of concurrent nonverbal auditory stimulation.

To investigate whether concurrent nonverbal sound sequences would affect visual-hemifield lexical processing, lexical-decision performance of 24 strongly right-handed students (12 men, 12 women) was measured in three conditions: baseline, concurrent neutral sound sequence, and concurrent emotional sound sequence. With the neutral sequence, Naveteru, Roy, Ovelac, and Steinling (1992) had observed a right greater than left cerebral blood flow, and an opposite pattern with the emotional sequence. In the present study, the neutral sound sequence induced a significant accuracy reduction for lexical decisions to stimuli presented in the left visual field. It is hypothesized that RH activation in response to neutral sounds interferes with the limited lexical processing resources of that hemisphere.

Adult↗
PubMed2000

Photoreceptor visual fields, ommatidial array, and receptor axon projections in the polarisation-sensitive dorsal rim area of the cricket compound eye.

We made intracellular recordings from the photoreceptors of the polarisation-sensitive dorsal rim area of the cricket compound eye combined with dye marking. By measuring visual field sizes and optical axes in different parts of the dorsal rim area, we assessed the optical properties of the ommatidia. Due to the large angular sensitivities (median about 20 degrees) and the high sampling frequency (about 1 per degree), the visual fields overlap extensively, such that a given portion of the sky is viewed simultaneously by a large number of ommatidia. By comparing the dye markings in the retina and in the optic lobe, the axon projections of the retinula cells were examined. Receptors R1, R2, R5 and R6 project to the lamina, whereas R7 projects to the medulla. The microvilli orientation of the two projection types differ by 90 degrees indicating the two analyser channels that give antagonistic input to polarisation-sensitive interneurons. Using the retinal marking pattern as an indicator for the quality of the intracellular recordings, the polarisation sensitivity of the photoreceptors was re-examined. The polarisation sensitivity of recordings from dye-coupled cells was much lower (median: 4.5) than that of recordings in which only one cell was marked (median: 9.8), indicating that artefactual electrical coupling between photoreceptors can significantly deteriorate polarisation sensitivity. The physiological value of polarisation sensitivity in the cricket dorsal rim area is thus typically about 10.

Animals↗
PubMed2005

Strength of visual percept generated by famous faces perceived without awareness: effects of affective valence, response latency, and visual field.

Participants who were unable to detect familiarity from masked 17 ms faces (Stone and Valentine, 2004 and Stone and Valentine, in press-b) did report a vague, partial visual percept. Two experiments investigated the relative strength of the visual percept generated by famous and unfamiliar faces, using masked 17 ms exposure. Each trial presented simultaneously a famous and an unfamiliar face, one face in LVF and the other in RVF. In one task, participants responded according to which of the faces generated the stronger visual percept, and in the other task, they attempted an explicit familiarity decision. The relative strength of the visual percept of the famous face compared to the unfamiliar face was moderated by response latency and participants' attitude towards the famous person. There was also an interaction of visual field with response latency, suggesting that the right hemisphere can generate a visual percept differentiating famous from unfamiliar faces more rapidly than the left hemisphere. Participants were at chance in the explicit familiarity decision, confirming the absence of awareness of facial familiarity.

Adult↗
PubMed1982

Oculoparalytic illusion: visual-field dependent spatial mislocalizations by humans partially paralyzed with curare.

In darkness, observers partially paralyzed with curare make large (greater thn 20 degrees) gaze- and dosage-dependent errors in visually localizing eye-level-horizontal and median planes, in matching the location of a sound to a light, and in pointing at a light. In illuminated, structured visual localization and pointing are accurate but errors in auditory-to-visual matches remain. Defects in extraretinal eye position information are responsible for all errors. The influence of extraretinal eye position information on visual localization is suppressed by a structured visual field but is crucial both in darkness and for intersensory localization if visual capture is prevented.

Auditory Perception↗
PubMed1998

Multifocal electroretinogram indicates visual field loss in acute zonal occult outer retinopathy.

PURPOSE: To report alterations of electrophysiologic tests, including the multifocal electroretinogram, in a case of acute zonal occult outer retinopathy. METHOD: We recorded photopic, scotopic, and single-flash electroretinograms and a multifocal electroretinogram in a 47-year-old woman with acute zonal occult outer retinopathy in the right eye. RESULTS: Her visual acuity was 20/20 in the right eye throughout the follow-up period. The electroretinograms indicated retinal impairment of the right eye, predominantly in the cones. The multifocal electroretinogram showed reduced responses corresponding to the visual field defect of the static perimetry. CONCLUSIONS: In acute zonal occult outer retinopathy, impairment of the retinal area results in a visual field defect. The multifocal electroretinogram can be useful in determining the location of the defect.

Acute Disease↗
PubMed1993

Geometry of the projection of the visual field onto the superior colliculus of the wallaby (Macropus eugenii). II. Stability of the projection after prolonged rearing with rotational squint.

At about the time of eye opening, one eye of seven tammar wallaby pouch young was surgically rotated about the optic axis by approximately 90 degrees. In adulthood the projection of the visual field through the rotated eye onto the contralateral superior colliculus was mapped electrophysiologically. Although apparently distorted, the projection could be coherently re-rotated mathematically to a reasonable copy of the normal projection from the opposite eye of the same animal, including details such as regional variations of the magnification factor. The same was true of three adult animals in which the eye rotation was done after anaesthesia immediately before the electrophysiological mapping. In animals in which the visual field seen through one eye, the other being normal, was rotated for the entire period of visual experience, there was no sign of compensation or rearrangement of the topographic map. Retinocollicular synaptic connections appear unmoved by such discordant visual experience.

Animals↗
PubMed2004

Visual field defects after temporal lobectomy -- comparing methods and analysing resection size.

OBJECTIVES: The frequency of visual field defects (VFD) after temporal lobe resections (TLR) was compared for two types of TLR and VFD frequency was correlated to resection size. METHODS: Pre- and post-operative perimetry results were analysed for 50 patients with TLR for medically intractable epilepsy. Thirty-three patients had a classical TLR and 17 had a TLR with less lateral extension. Post-operative MRIs were studied in 34 patients by scoring resection size in 12 compartments in the temporal lobe. RESULTS: Twenty-five patients developed a VFD. In the classical TLR group, 16 of 33 developed a VFD, compared with nine of 17 in the other group. The resection points were higher for the VFD group in the most anterior compartment studied, in the superior temporal gyrus. CONCLUSIONS: There was no clearcut difference in VFD frequency between the surgical methods studied. However, the compartmentalized analysis disclosed a relation between the extent of resection in the anterior part of the superior temporal gyrus and VFD frequency.

Adolescent↗
PubMed2004

The effects on the intraocular pressure and visual field resulting from a switch in the treatment from timolol to betaxolol.

Patients with primary open-angle glaucoma (POAG) were dosed twice-daily with 0.5% timolol maleate for 2 years, followed by 2 years of twice-daily dosing with 0.5% betaxolol hydrochloride. The changes in intraocular pressure (IOP) and effects on visual field by each treatment were monitored over this 4-year period. Both the timolol and betaxolol treatments controlled IOP. The mean MD (mean deviation in visual field) values at 24 months of the timolol treatment were -6.18 dB (decibels) and -5.32 dB. Mean MD baseline values following 24 months of the timolol treatment produced 2.31 dB and 0.95 dB reductions in sensitivity in the right and left eyes, and the reduction in the right eye was statistically significant (p < 0.01). The mean MD values after 24 months of the betaxolol treatment were -3.82 dB in the right eyes, an increase of 2.36 dB, and -4.05 dB in the left eyes, up by 1.28 dB. The results from this clinical trial demonstrated that betaxolol was superior over timolol in improving mean retinal sensitivity.

Adult↗
PubMed2002

The learning effect in visual field testing of healthy subjects using frequency doubling technology.

PURPOSE: To evaluate the presence, duration and magnitude of a learning effect in serial visual field (VF) testing, using the commercially available frequency doubling technology (FDT) instrument. PATIENTS AND METHODS: 21 healthy adults with no prior VF experience underwent 6 serial VF tests, using the full-threshold C-20 program of the Zeiss-Humphrey FDT analyzer, on one randomly chosen eye. Tests were spaced at least two days apart. RESULTS: The average mean sensitivity was 32.37 +/- 2.6 dB; the average mean deviation (MD) was 1.22 +/- 1.8 dB. The MD at the first examination (0.28 +/- 2.1 dB) was significantly poorer than at any of the other testing sessions (p<0.003). Similarly, the mean sensitivity at the first examination (31.16 +/- 3.0 dB) was significantly lower than any other testing session (p<0.004). The proportion of improvement from the first to the second session was 63% and 65% of the total improvement, for mean sensitivity and MD, respectively. Mean test duration showed a modest reduction, from 4.40 +/- 0.3 minutes in the first session to 4.17 +/- 0.4 minutes in the last session (p = 0.023). A sub-analysis comparison of the different VF segments showed a more prominent learning effect in the peripheral and nasal visual segments (p<0.0001). CONCLUSION: Baseline measurements should best rely on the second testing session, since MD and mean sensitivity are somewhat poorer when subjects with no prior VF experience are first tested on the FDT instrument. This may be especially true for the purpose of following patients over time.

Adult↗
PubMed1987

The projection of the visual field upon the retina of the pigeon.

Co-ordinates in the visual field of the pigeon eye were located in the eye cup anatomically by marking the position of the trans-scleral image. The retinal horizon and vertical meridian at azimuths 0 deg (frontal field) and 90 deg (lateral field) were located. Approximately 18 deg of binocular field are available in frontal vision and the frontal meridian projects to temporal retina outside the red field. Spatial distributions of ganglion cells, displaced ganglion cells, and centrifugal terminals were located in the eye cup. Retinal magnification factors in the posterior pole and temporal periphery are close to 120 microns/deg.

Animals↗
PubMed2005

Visual field testing in glaucoma Medicare beneficiaries before surgery.

OBJECTIVE: The standard of care for progressive glaucoma that requires medical or surgical intervention includes visual field (VF) testing at least annually. This study aims to assess how commonly ophthalmologists perform VF testing before planned glaucoma surgery in the Medicare population, and whether variations in conformance occur across demographic and clinical subgroups. DESIGN: Retrospective, observational, population-based analysis. PARTICIPANTS: Thirteen thousand seven hundred fifty-three Medicare beneficiaries. METHODS: Data were obtained from a 5% random sample of Medicare beneficiaries undergoing glaucoma surgery in the United States from 1995 to 1999. The proportion of patients with evidence of at least 1 VF examination in the year before glaucoma surgery was determined. MAIN OUTCOME MEASURE: Rate of VF testing in the year before glaucoma surgery. RESULTS: Overall, 70% of patients had at least 1 VF test in the year preceding glaucoma surgery. This rate was significantly lower (P<0.001) in patients > or =85 years (56%), blacks (64%), patients with race other than white or black (66%), patients with diabetic retinopathy (60%), and patients with bilateral blindness (47%). CONCLUSIONS: The use of VF testing before surgery in glaucoma Medicare beneficiaries is suboptimal relative to the recommended standard of care. Underutilization is of particular concern in blacks, who are at increased risk of glaucomatous damage. Quality-of-care initiatives are needed to facilitate appropriate preoperative evaluations of glaucoma Medicare beneficiaries for glaucoma surgery.

Aged↗
PubMed1977

The visual field examination and its automation.

An automated system for examination of the visual fields is described. The entire campimetric examination was simulated in order to enable an in-depth analysis of actual examinations. The program runs on a HP2100 computer with a 16K core. The main advantages of the system are: greater speed, less patient fatigue, greater reliability, repeatability and accuracy.

Diagnosis, Computer-Assisted↗

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