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PubMed1988

Progression of visual defects in ischemic optic neuropathy.

Six patients with nonarteritic ischemic optic neuropathy experienced worsening of visual acuity and field loss during the six-week period after onset (range, three to six weeks), without apparent ophthalmoscopic changes. Thereafter, visual function remained unchanged. Various medications were used, but none prevented deterioration of visual function. Although not a widely recognized phenomenon, progression of visual deficit occurred in these patients in the early weeks after onset of ischemic optic neuropathy.

Female↗

PubMed2000

Tests of the mouse visual system.

To apply the approach of forward genetics (e.g., gene identification with mutagenesis and screening, followed by positional cloning) to the mouse, it is necessary to have available screening tests that can be applied rapidly to individual mice and that give a reliable assessment of visual function. This paper reviews the strengths and limitations of two anatomical tests related to visual function, fundus examination and retinal histological examination. Two tests that do not depend on behavior of a conscious animal are reviewed: the electroretinogram and the visual evoked potentials of the cortex. Eight behavioral tests are also summarized: maze-based tests, cued fear conditioning, tests based on conditioned suppression, visual placing, optokinetic nystagmus, pupillary reflex, and light-induced shifts in circadian phase. It is recommended that retinal histology, the electroretinogram, and visual-evoked potentials be used at the present time for screening because they assess the function and structure of the visual system rapidly and reliably. In fact, the electroretinogram (or visually evoked potentials) can be recorded from several animals simultaneously in response to the same stimulus. It is also recommended that efforts be made to develop more appropriate, automated, behavioral tests of visual perception than are now available, particularly tests that rely solely on rewarding visually evoked behavior. Two other promising behavioral tests are cued fear conditioning and variants of maze tests.

Animals↗

PubMed2001

A randomized trial of intravenous immunoglobulin in inflammatory demyelinating optic neuritis.

OBJECTIVE: To determine whether IV immunoglobulin (IVIg) reverses chronic visual impairment in MS patients with optic neuritis (ON). METHODS: In this double-blind, placebo-controlled Phase II trial, 55 patients with persistent acuity loss after ON were randomized to receive either IVIg 0.4 g/kg daily for 5 days followed by three single infusions monthly for 3 months, or placebo. RESULTS: The trial was terminated by the National Eye Institute because of negative results when 55 of the planned 60 patients had been enrolled. Fifty-two patients completed the scheduled infusions, and 53 patients completed 12 months of follow-up. Analysis of this data indicated that a difference between treatment groups was not observed for the primary outcome measure, improvement in logMAR visual scores at 6 months (p = 0.766). Exploratory secondary analyses suggested that IVIg treatment was associated with improvement in visual function (including logMAR visual scores at 6 months and visual fields at 6 and 12 months) in patients with clinically stable MS during the trial. CONCLUSIONS: IVIg administration does not reverse persistent visual loss from ON to a degree that merits general use.

Adult↗

PubMed1986

Visual results and prognostic factors for vision following surgery for stage V retinopathy of prematurity.

As our surgical techniques improve we are able to achieve anatomic retinal reattachment in 48% of eyes with advanced retinopathy of prematurity. Only 31% of these eyes, however, have achieved visual function by the six-month follow-up visit. In an attempt to determine the factors that lead to better visual outcome, we analyzed 85 eyes of 45 children who underwent surgical therapy for Stage V retinopathy of prematurity by one surgeon. These eyes were followed from 6 to 36 months. We analyzed the timing of surgery, retinal configuration, subretinal fluid composition, and appearance of retinal pigment epithelium following resolution of detachment as these related to visual results. We also used visual evoked response testing in an attempt to predict which eyes might achieve visual function. Children with best visual results tended to have rapidly regressing vascular activity, were operated earlier, and had little subretinal exudate sparing the macula and little alteration of RPE following retinal reattachment, and if measured, low iron concentration in subretinal fluid.

Child, Preschool↗

PubMedDate not supplied

[Combination of new electrophysiological and imaging techniques in the study of primary visual cortex function].

INTRODUCTION: This work summarizes current research focused on explaining orientation selectivity of primary visual cortex (V1), and describes the electrophysiological and imaging techniques than are being used. DEVELOPMENT: The study of orientation selectivity in V1 is key to understanding the cortical mechanisms implicated in the processing of sensory information, but this enterprise has proved more challenging than previously thought and there is no consensus about the best model to explain V1 neurons activity. Ongoing research is focused on determining the importance of the different inputs that a cortical cell receives (thalamic and lateral cortical inputs), and their link to cortical architecture. To achieve that, current research is combining optical imaging techniques with intracellular recordings of V1 neurons. Recent findings have found differences in the synaptic integration performed by neurons located in the iso orientation domains vs orientation centers of the functional V1 map. CONCLUSIONS: Data describing synaptic activity combined with the cortical functional structure are yielding new clues about V1 computation, suggesting that there is more than one mechanism capable of generating orientation selectivity.

Electrophysiology↗

PubMed2001

Perimetric visual field and functional MRI correlation: implications for image-guided surgery in occipital brain tumours.

OBJECTIVE: To compare the results of visual functional MRI with those of perimetric evaluation in patients with visual field defects and retrochiasmastic tumours and in normal subjects without visual field defect. The potential clinical usefulness of visual functional MRI data during resective surgery was evaluated in patients with occipital lobe tumours. METHODS: Eleven patients with various tumours and visual field defects and 12 normal subjects were studied by fMRI using bimonocular or monocular repetitive photic stimulation (8 Hz). The data obtained were analyzed with the statistical parametric maps software (p<10(-8)) and were compared with the results of Goldmann visual field perimetric evaluation. In patients with occipital brain tumours undergoing surgery, the functional data were registered in a frameless stereotactic device and the images fused into anatomical three standard planes and three dimensional reconstructions of the brain surface. RESULTS: Two studies of patients were discarded, one because of head motion and the other because of badly followed instructions. On the remaining patients the functional activations found in the visual cortex were consistent with the results of perimetric evaluation in all but one of the patients and all the normal subjects although the results of fMRI were highly dependent on the choices of the analysis thresholds. Visual functional MRI image guided data were used in five patients with occipital brain tumours. No added postoperative functional field defect was detected. CONCLUSIONS: There was a good correspondence between fMRI data and the results of perimetric evaluation although dependent on the analysis thresholds. Visual fMRI data registered into a frameless stereotactic device may be useful in surgical planning and tumour removal.

Adult↗

PubMed2006

Travoprost versus latanoprost combinations in glaucoma: economic evaluation based on visual field deficit progression.

OBJECTIVE: Changes in intraocular pressure (IOP) are known to be related to visual field deficit progression, although multiple models of this relationship exist. In addition, visual functioning is known to affect medical costs. The objective of this study was to project visual field deficit progression and subsequent costs based on clinical trial data. RESEARCH DESIGN AND METHODS: Using data from a randomized, 12-month, double-masked study, we compared the use of a fixed combination of travoprost 0.004%/timolol 0.5% (T/T) versus a fixed combination of latanoprost 0.005%/timolol 0.5% (L/T) on visual field deficit progression and associated costs. We applied published algorithms linking IOP to visual field changes to calculate the likelihood of visual field deterioration by treatment group. Differences in medical care costs were estimated using guideline-recommended practice patterns, Medicare hospital costs, and published estimates of differences in hospitalization by visual functioning. MAIN OUTCOME MEASURES: Increase in visual field deficit progression rates, increase in annual hospital days per subject, and increase in annual hospital, outpatient, and total costs per subject. RESULTS: Predicted visual field deficit progression for T/T patients was less than that for L/T patients (not statistically significant). Projected annual medical care costs were 43 dollars lower for T/T vs. L/T patients. CONCLUSIONS: By applying published algorithms linking IOP to visual field changes, this study projected long-term visual field deficit and associated costs. Use of a fixed travoprost/timolol solution may lead to less long-term visual field deficit progression and lower annual medical care costs than a fixed latanoprost/timolol solution. DISCUSSION: The use of clinical trial data may limit the applicability of these findings. However, this analysis of direct medical costs only is likely a conservative estimate of the costs associated with visual field deficits.

Adult↗

PubMed1982

[Functional eye testing in the mentally retarded].

Simple clinical testing procedures, devised by Sheridan, to test visual functions in young and/or handicapped children are discussed. Using these methods, combined with experience obtained in studying visuo-motor behaviour in cats, vision was tested in 30 severely mentally handicapped children. For 17 of these, it was unclear whether they possessed any usable visual functions. For 29 out of the 30 tested children it was possible to reach a reasonably confident conclusion regarding presence or absence of functional vision. Thirteen patients appeared to be functionally blind. In 17 children the size of the visual field could be determined; 7 showed normal, 10 restricted visual fields. In 6 children acuity could be measured. The importance of early detection of visual defects is discussed.

Child↗

PubMed1993

Quantal and visual efficiency of fluorescence in the lens of the human eye.

PURPOSE: To document quantitatively the fluorescence in the human lens relevant to its interference with visual function. To explain quantitatively the experimental findings relative to loss of visual function. To study the relation between the fluorescence and the light transmission of the lens. METHODS: Three normal lenses, from 22-, 28-, and 69-year-old donors, were used. Fluorescent light was induced by a 4-mm diameter pencil beam of 380, 400, or 420 nm. It was measured as a function of the deflection angle from -10 to 150 degrees for different wavelengths. RESULTS: The shapes of the emission spectra were comparable to those reported in the literature. Total quantal efficiency of fluorescence was between 5% for 69 years and 380 nm excitation and 0.4% for 22 years and 420 nm excitation. The forward intensity was less than the backward intensity because of secondary absorption. CONCLUSIONS: Fluorescence of the lens causes light with wavelengths of 420 nm and lower to be much more visually effective. A marked homogeneous veil is added to the point spread function. The total increase in luminous efficiency was a factor 3 to 6 at 400 nm, and a factor 70 to 150 at 380 nm. For other visual effects (glare) the increase can be larger.

Adult↗

PubMed1997

Cerebral vascular malformations adjacent to sensorimotor and visual cortex. Functional magnetic resonance imaging studies before and after therapeutic intervention.

BACKGROUND AND PURPOSE: It is not known how cerebral vascular malformations affect the function of the surrounding brain. Functional magnetic resonance imaging (fMRI) can provide information about normal functional neuroanatomy and its alteration by vascular lesions and therapeutic intervention. METHODS: We performed fMRI studies in 24 patients harboring vascular malformations adjacent to primary somatosensory, motor, and visual cortex. The fMRI studies consisted of the acquisition of an image time series coupled with functional activation of motor, sensory, or visual cortex in both hemispheres. Activated voxels were identified using frequency domain analyses, and their number and anatomic location were compared between the affected and unaffected hemispheres. RESULTS: Every patient capable of performing the desired task showed functional activation. Eight patients without neurological deficits showed a symmetrical pattern of activation between the hemispheres. Each had a vascular malformation located one or more gyri from the functional region imaged. Three patients showed hemispheric symmetry in the location of activated cortex but with a marked asymmetry in the number of activated voxels. Each harbored vascular malformations located within one gyrus of the functional region and showed either subtle or no neurological deficit. Eleven patients showed hemispheric asymmetry in the location of activated cortex. In 6, the anatomic displacement appeared to be due to a mass effect of the lesion. In 5, the activation occurred at a different anatomic locale, and the patients exhibited gross neurological deficit in the respective function. Posttherapeutic changes in functional activation reflected elimination of the mass effect or recovery of clinical function. CONCLUSIONS: Systematic fMRI studies are possible in patients with vascular malformations in brain regions adjacent to primary somatosensory, motor, and visual cortex. Displacement of the activated region and hemispheric asymmetry in the number of activated voxels in the functional regions appear to reflect the anatomic and physiological impact of the vascular malformation. Changes in fMRI findings after intervention reflect the consequences of therapy and parallel clinical recovery.

Adolescent↗

PubMed1994

Relation between neonatal cranial ultrasound abnormalities and cerebral visual impairment in infancy.

A prospective follow-up study was conducted of a cohort of 65 at-risk neonates to assess the predictive value of neonatal cranial ultrasound abnormalities for cerebral visual impairment in infancy. Visual function was assessed using the acuity card procedure and behavioural visual responses were tested. Normal visual function was found in controls as well as in infants with small haemorrhages or mild leukomalacia. Infants with large haemorrhages performed poorly at 40 weeks postmenstrual age, but recovered to within the normal range in the first half year. In contrast, of the infants with extensive cystic leukomalacia, four of nine preterm infants and three of four term infants were severely visually impaired at 18 months. In the more mature infants, the cystic lesions extended deeper into the subcortical white matter, and this appeared to be associated with a worse visual outcome. Cystic leukomalacia proved to be highly predictive of cerebral visual impairment in infancy.

Cerebral Hemorrhage↗

PubMed2005

Vision requirements for driver's license examiners.

PURPOSE: The purpose of this study was to determine the vision requirements for licensing and registration examiners (LREs) of motor vehicle drivers in the state of California. METHODS: A comprehensive investigation was conducted that included a literature review, consideration of the Americans with Disabilities Act, analysis of materials with a subject matter expert panel, an overview of visual function tests, a formal job analysis, job audits and site visits to licensing offices, analysis of accidents and critical incidents, performance of simulation studies, and a review and evaluation of all materials collected during the study. RESULTS: Based on this analysis, three visual functions (best-corrected visual acuity, peripheral visual field extent, and color vision) were determined to be important for performing the essential job functions of an LRE. It was recommended that LREs demonstrate a best-corrected visual acuity of at least 20/20 in each eye, a peripheral visual field of at least 100 degrees diameter of horizontal and vertical extent in each eye (with no evidence of scotomas or pathologic areas of nonseeing within the visual field), and color vision capabilities that permit a passing score on the Farnsworth Panel D-15 color vision test. DISCUSSION: The findings of this investigation provide a strong basis for specifying and justifying vision requirements for performing essential job functions for an LRE in the state of California.

Adult↗

PubMedDate not supplied

Visual acuity losses in pigeons with lesions of the nucleus of Edinger-Westphal that disrupt the adaptive regulation of choroidal blood flow.

Choroidal blood flow (ChBF) in birds is regulated by a neural circuit whose components are the retina, the suprachiasmatic nucleus, the medial division of the Edinger-Westphal nucleus (EWM), the ciliary ganglion, and the choriod. We have previously shown that lesions of EWM appear to result in pathological alterations in the retina. To determine whether EWM lesions also lead to altered visual functions, we have examined the effects of EWM lesions on visual acuity in pigeons. Bilateral lesions of EWM were made electrolytically, and visual acuity for high-contrast, square-wave gratings was determined behaviorally about 1 year later and compared to that of a group of pigeons that had received sham lesions of EW about 1 year prior to acuity testing. Because lesions targeting EWM invariably resulted in damage to the adjoining lateral part of the Edinger-Westphal nucleus (EWL), which controls pupillary constriction and accommodation, two additional control groups were studied. In one such control group, bilateral lesions in the area pretectalis (AP), which innervates the pupillary control part of EWL and thereby controls pupillary constriction, were made and the effects on visual acuity determined about 1 year later. In the second such control group, the effects of acute accommodative and pupillary dysfunction on acuity were studied in pigeons made cycloplegic. The accuracy of all lesions was later confirmed histologically. The mean acuities of birds with AP lesions (9.1+/-1.4 cycles/deg) and sham lesions (7.1+/-1.5 cycles/deg) were not significantly different from normal, based on published normative data on pigeons. In contrast, pigeons with lesions that completely destroyed EW bilaterally showed visual acuity (2.7+/-0.1 cycles/deg) that was well below the acuity of the sham and AP-lesion control groups. The acuity of the cycloplegic pigeons (4.8+/-0.3 cycles/deg) and one pigeon with a nearly complete bilateral EWL but a unilateral EWM lesion (6.4 cycles/deg) indicated that only about half of the loss with a bilateral EW lesion could be attributed to accommodative dysfunction. Thus, bilateral destruction of EWM appears to have led to a loss in visual acuity. This conclusion suggests that disruption of adaptive neural regulation of ChBF may impair visual function. Destruction of EWM was, however, associated with damage to the somatic components of the oculomotor and trochlear nuclei. The possibility cannot be excluded that such damage also contributed to the acuity loss.

Adaptation, Physiological↗

PubMed1998

Visual field defects in optic neuritis and anterior ischemic optic neuropathy: distinctive features.

BACKGROUND: We analyzed the value of visual-field defects in the differential diagnosis of optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (AION). METHODS: Ninety-nine consecutive patients with acute-onset optic neuropathy formed the basis for this study. Compressive and vasculitic neuropathies were excluded. Eighty-six patients fulfilled the criteria for either ON (50 patients): < or = 35 years, normal disk, recovery of visual function, or AION (36 patients): > or = 60 years, swelling of the disk, no recovery of visual function. Without knowledge of other clinical data, visual fields obtained by Gold-mann perimetry were classified into five types of defects (forced choice). With the correct diagnosis at hand, fields were reviewed for characteristic features. RESULTS: Forced-choice classification into defect types [%]: Central scotoma ON 68, AION 18; superior altitudinal defect ON 13 AION 7; inferior altitudinal defect ON 8, AION 52; peripheral defect ON 1, AION 5; diffuse defect ON 10, AION 18. Search for pathognomonic defects: a scotoma centered on the fixation point with a sloping border occurred exclusively in ON (25 of 50 patients). An inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, occurred only in AION (10 of 36 patients). A steep centrocecal scotoma occurred in 3 of the 36 AION cases and not at all in the ON cases. Scotomas in the center breaking through to the periphery, superior altitudinal defects (with a sloping border along the horizontal meridian) and diffuse depressions verging on blindness occurred in both ON and AION. CONCLUSION: A sctoma centered on the fixation point with a sloping border is highly characteristic of ON, while an inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, is highly characteristic of AION. To identify these diagnostic criteria, it can be necessary to examine full fields. With restriction of perimetry to 30 degrees a large central scotoma can be mistaken for a diffuse defect and the border in the nasal periphery can be missed.

Acute Disease↗

PubMed2006

Bilateral optic neuropathy associated with multiple myeloma.

A 51-year-old man had reduced vision and bilateral optic disc swelling as the initial clinical manifestation of multiple myeloma. Brain imaging failed to disclose any abnormalities. Before any therapy was begun, visual function began to improve substantially. Three months after chemotherapy was started, visual function and optic disc appearance returned to near normal. There were no features to suggest polyneuropathy-organomegaly-endocrinopathy-M protein-skin changes (POEMS) syndrome. Visual loss in myeloma is usually caused by compression or infiltration of the optic nerves by tumor. The mechanism of the optic neuropathy in this case remains unknown.

Diagnosis, Differential↗

PubMed1999

Surgical treatment in nystagmus.

PURPOSE: To evaluate the effect of symmetric recession surgery on all four horizontal rectus muscles in the treatment of patients with congenital motor nystagmus and sensory nystagmus secondary to albinism, dyschromatopsia and degenerative myopia. METHODS: Prospectively, four patients with a diagnosis of congenital motor nystagmus and eight patients with sensory nystagmus were operated on. The amount of recession was determined according to the ocular alignment of the patients. Electronystagmographic recordings were conducted in every patient pre-operatively and post-operatively, as well as an ophthalmological examination. RESULTS: Mean age of the patients at the time of the first visit was 6.7 +/- 4.2 years (range 9 months to 14 years) and mean age at the time of operation was 8.3 +/- 2.7 years (range 6-14 years). In 8 cases an equal amount of weakening of the four horizontal recti was done, whereas in 2 cases more recession on the lateral recti due to exotropia and in 2 cases more recession on the medial recti due to esotropia was performed. Mean follow-up time was 15.8 months (min. 6 months, max. 28 months). Improvement in visual function was achieved in 7 patients. Amplitude decreased in 9 patients. One patient had a decrease in visual acuity due to progression of her primary macular degeneration. Improvement in head posture was seen in 3 patients and there was no change in the head posture in 2 patients. One patient acquired head posture after surgery. Restriction of motility was seen in none of the patients after surgery in spite of large amounts of recession. Recession of horizontal recti decreased nystagmus amplitude and frequency in 81.8% of patients. Improvement in visual function, measured as an increase in visual acuity in terms of Snellen lines, was achieved in 63.6% of patients. CONCLUSION: Symmetric recession of the horizontal rectus muscles is shown to be a successful procedure to perform in nystagmus patients, resulting in an increase in visual acuity and a decrease in nystagmus amplitude and frequency. It is a reliable alternative to the Kestenbaum operation and is easier to perform surgically.

Adolescent↗

PubMed2003

Visual backward-masking deficits in schizophrenia: relationship to visual pathway function and symptomatology.

Patients with schizophrenia have information processing deficits which can be measured using visual backward-masking (VBM) tasks. There are two types of visual pathways: transient and sustained. The former is more sensitive to low spatial frequency (LSF) and the latter to high spatial frequency (HSF) stimuli. It has been hypothesized that the VBM deficit in schizophrenia is due to an overactive transient channel response to the mask. To examine this hypothesis, patients with schizophrenia and comparison volunteers were tested on a traditional backward-masking task as well as on tasks that altered the mask to bias stimulation toward transient (LSF) or sustained (HSF) channels. Medication effects and relationship to symptomatology were also examined. Patients with schizophrenia showed a significant deficit on the traditional backward-masking task and were also significantly impaired on the LSF- and HSF-masking tasks, though a differential deficit was not found on the latter two tasks. A U-shaped function, indicative of masking by interruption, was found on the LSF- and HSF-masking tasks. Masking performance was not altered when the same patients were tested on and off medication, and performance was related to positive and negative symptoms. In conclusion, the finding of a deficit in patients with schizophrenia on tasks producing a U-shaped function suggests that an aberrant transient response to the mask is producing increased interruption of the sustained response to the target.

Adult↗

PubMed1986

The colour-matching functions and visual research.

The following points are examined: the problem of how to define the colour of a stimulus used in visual research; the limited relation of the colour-matching functions to the spectral sensitivity curves of the individual colour receptors in the retina; and the case for abandoning luminance as a colorimetric variable and lightness as a colour appearance variable.

Color↗