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At least 487 records · Page 27Linked to original sources

PubMed1984

Critical period plasticity for visual function: definition in monocularly deprived rats using visually evoked potentials.

VEPs were used to study the effects of visual deprivation and to define the critical period in the hooded rat. It is shown that monocular deprivation in young animals reduces both the visual acuity and the contrast sensitivity of the deprived eye and that the depth of attenuation depends upon the age at onset of deprivation. This suggests that the critical period is almost over by 6 weeks postnatally. This simple recording technique might be useful in studying amblyopic children and in defining more clearly the critical period for human vision.

Aging↗

PubMed1998

[Visual evoked potentials and static perimetry in functional visual deficits].

The author presents application of visual evoked potentials and static perimetry in hysterical amblyopia, psychical blindness, malingerers, amblyopia, cortical blindness and visual acuity assessment in infants. The author emphasizes the influence of multiple factors on the results and interpretation of the examination.

Evoked Potentials, Visual↗

PubMed2006

[Early clinical evaluation of visual function in patients with age-related cataract].

OBJECTIVE: To investigate the characteristics of visual acuity, contrast sensitivity and glare contrast sensitivity in age-related cataract patients. METHODS: In this study, 115 eyes of 66 age-related cataract patients with a best corrected visual acuity of 0.5 or better, who had been classified into cortical cataract group (50 eyes of 31 subjects), nuclear sclerosis group (32 eyes of 17 subjects), posterior subcapsular cataract group (33 eyes of 18 subjects); and control group (34 eyes of 34 subjects) were examined with a contrast glare tester to assess contrast sensitivity and glare contrast sensitivity. RESULTS: There were statistically significant differences among contrast sensitivity and glare contrast sensitivity in the cataract patients with different visual acuity at low, medium spatial frequency (P < 0.01); there were no statistically significant differences among those at high spatial frequency (P > 0.05). Cortical cataract was associated with the contrast sensitivity at low, medium spatial frequency, where the glare contrast sensitivity fell into at low, medium and high spatial frequency; in the patients with cataract of nuclear sclerosis was associated with the contrast sensitivity at low spatial frequency, where the glare contrast sensitivity was at low, medium and high spatial frequency; in contrast to posterior subcapsular cataract both the contrast sensitivity and glare contrast sensitivity (at low, medium, high spatial frequency) were lower than normal eyes (P < 0.05). Each spatial frequency of contrast sensitivity and glare contrast sensitivity in 57 cataract eyes with a best corrected visual acuity of 0.8 or better were lower than normal eyes. In those eyes the contrast sensitivity at low spatial frequency and glare contrast sensitivity at low and high spatial frequency had statistically significant difference compared with control (P < 0.05); other spatial frequency had no statistically significant difference among groups (P > 0.05). The glare contrast sensitivity in cataract eyes was lower than contrast sensitivity at visual angle of 6.3 degrees, 4.0 degrees, 2.5 degrees, 1.6 degrees, 1.0 degrees, the difference was statistically significant (P < 0.01). CONCLUSION: Contrast sensitivity and glare contrast sensitivity are reliable in evaluating visual function in the patients with early age-related cataract.

Adult↗

PubMed2002

The effect of a hockey visor and sports goggles on visual function.

BACKGROUND: Despite the potential for eye injury, most hockey players in the National Hockey League do not use a protective face shield. We examined the effect of a hockey visor and sports goggle on visual function to see whether visual impediment is a substantial factor in the resistance to use of protective eyewear. METHODS: We measured Snellen visual acuity, Ishihara colour vision and contrast sensitivity and performed Humphrey central 30 degrees and peripheral 30 degrees to 60 degrees threshold perimetry in eight volunteers (10 eyes) with and without a sports goggle and a hockey visor (half face shield). Subjects with normal acuity and normal confrontation fields who did not require presbyopic correction at near were enrolled. Five subjects (10 eyes) had further testing with threshold perimetry of the temporal crescent. The order in which the tests were performed (no mask first, visor first or goggle first) was alternated between subjects. RESULTS: There was no difference in Snellen acuity or Ishihara colour vision, and no statistically significant difference in contrast sensitivity or foveal threshold with or without protective eyewear. The visor caused a statistically significant decrease in the central 30 degrees mean deviation index compared to no mask (p = 0.001), but the goggle did not. Each of the peripheral quadrant threshold totals was significantly decreased with the visor compared with no mask (p < 0.05). The 30 degrees to 60 degrees temporal field was better preserved with the goggle than with the visor, but the nasal peripheral field was worse with the goggle than with the visor. Both the visor and the goggle caused a statistically significant decrease of more than 4 decibels in the temporal crescent threshold (p = 0.000). INTERPRETATION: Protective eyewear does not adversely affect Snellen acuity, contrast sensitivity, Ishihara colour vision or foveal threshold. The central 30 degrees field of vision is not affected by the sports goggle and is minimally depressed by the hockey visor. The goggle better preserves the temporal midperipheral field, but, unlike the visor, the goggle caused a monocular nasal lens rim scotoma. Both devices caused a depression of more than 4 dB of the far temporal field beyond 60 degrees (temporal crescent).

Adult↗

PubMed1995

Optimal temporal frequencies in oscillatory movement hyperacuity measurements of visual function in cataract patients.

Hyperacuity tasks have been suggested for the assessment of potential visual function in the presence of cataracts. To test this suggestion, hyperacuity thresholds for an oscillating bar were measured in 30 subjects with idiopathic cataract and in 24 age-matched normals over a range of oscillation frequencies. Each subject's cataract was categorized using the Oxford Clinical Cataract Classification and Grading System. Cataract was found to have a significant effect on thresholds, although a differential morphological effect on thresholds was equivocal. Thresholds at higher temporal frequencies were significantly raised when compared to the normal group. The main conclusion to be drawn from this study is that motion hyperacuity thresholds appear unaffected by cataract at low oscillation frequencies and should be used in preference to higher frequencies in the assessment of such patients.

Aged↗

PubMed1998

Visual functioning and quality of life outcomes among cataract operated and unoperated blind populations in Nepal.

BACKGROUND: Visual acuity and vision related quality of life outcomes in cataract surgery were evaluated in a population based survey in two geographic zones in Nepal. METHODS: Case finding was based on random sampling using a stratified cluster design with door to door enumeration of people aged > or = 45 years followed by eye examinations at village sites. All aphakics/pseudophakics, those with visual acuity less than 6/60 in either eye, and a sample of those with normal visual acuity were administered visual functioning (VF) and quality of life (QOL) questionnaires. RESULTS: 15% of the 159 cataract operated cases had presenting visual acuity > or = 6/18 in both eyes, 38% with best corrected visual acuity. 21% were still blind with presenting visual acuity < 6/60 in both eyes, 7% with best correction. On a 0-100 scale, mean VF and QOL scores were 87.2 and 93.9 respectively in normally sighted unoperated individuals, dropping to 15.6 and 29.5 for those severely blind (< 3/60). Among the cataract operated, mean VF and QOL scores were 47.5 and 55.4, respectively. VF and QOL scores correlated with vision status at statistically significant levels (p < 0.0001). CONCLUSION: Cataract surgery outcomes, whether measured by traditional visual acuity or by patient reported VF/QOL, are at levels many would consider unacceptably low. It is apparent that in the quest to reduce cataract blindness much more attention must be given to improving surgery outcomes.

Aged↗

PubMedDate not supplied

Visual function following congenital cataract surgery.

To evaluate the results of congenital cataract extraction and postoperative visual function, we retrospectively reviewed the records of 95 patients who underwent pars plana (plicata) lensectomy or aspiration surgery. Forty-nine percent of the patients with bilateral aphakia and 25% with bilateral pseudophakia had a Landolt visual acuity of 0.5 or above at the final visit. The figures were 31% and 66% for patients with unilateral aphakia and pseudophakia, respectively. Eight patients (16.3%) with bilateral and 2 patients (5.8%) with unilateral cataract for whom contact lenses were prescribed after surgery attained fine stereopsis. Five of 8 patients (62.5%) with unilateral cataract who had intraocular lens implantation ended up with gross or fine stereopsis. We stress that very early surgery and optical correction in the sensitive period of binocular visual development should be instituted, especially in the presence of dense opacities. A good postoperative visual outcome can be achieved in patients undergoing late surgery if the opacities are light or partial in nature. We also reemphasize the importance of aggressive and diligent visual rehabilitation and occlusion therapy against amblyopia.

Cataract↗

PubMedDate not supplied

Curved-surface projection: an alternative method for visualizing functional MR imaging results.

Curved-surface projection (CSP) is a new technique for visualizing functional MR imaging data. This technique helps in identifying anatomic structures by demonstrating the whole gyral and sulcal pattern of the brain at once. Compared with other techniques, CSP preserves the spatial relation of eloquent areas to lesions. Especially in neurosurgical patients with space-occupying lesions, CSP helps in assigning the anatomy to its function.

Astrocytoma↗

PubMed1984

Rocket-ship psychophysics. Assessing visual functioning in young children.

A set of psychophysical procedures is described for rapidly measuring visual functions such as spatial contrast sensitivity, flicker fusion, and rod and cone two-color increment thresholds in young children. The psychophysical procedures, disguised as electronic space games, use a forced-choice paradigm combined with the method of descending limits. Because children enjoy the tasks and are highly motivated, the tests yield good sensory thresholds in a short period of time. However, when thresholds from 6-8-year-old children are compared with those of adults, the children have slightly higher thresholds for all of the functions tested. The differences are ascribed to the tendency of children to adopt a guessing strategy when stimuli are close to threshold.

Adolescent↗

PubMed2003

The effect of membrane differential filtration on the colloid osmotic pressure in patients with age-related macular degeneration: significance to visual function?

To investigate the effect of membrane differential filtration (MDF) on plasma colloid osmotic pressure (COP) and visual functions in age-related geographic macular degeneration (AMD). Ten consecutive patients with non-exudative AMD underwent one MDF cycle. Primary endpoint was COP. Secondary endpoints were visual acuity and the mean defect of visual field. The COP was markedly reduced after one MDF cycle by 23.9% (P = 0.001). Compared with the baseline examination, visual acuity and the mean defect of visual field improved significantly after MDF. A significant positive correlation was found between the improvement in visual field and the decrease in COP (Pearson's coefficient = 0.65; P = 0.04). Membrane differential filtration lowers plasma colloid osmotic pressure in patients with non-exudative AMD. Based on the observation that visual field and COP are correlated, one may hope for a means to improve decreased central retinal function in eyes with geographic AMD by modulation of COP plasma level.

Female↗

PubMed1994

Longitudinal study of visual functions in young insulin dependent diabetics.

The aim of this study was to compare the visual functions of a group of young insulin dependent diabetes mellitus patients (IDDMs), (n = 42) with an age and sex matched control group (n = 24). Examinations were carried out every 3 months for 2 years. There were no significant differences in visual acuity between IDDMs and control subjects. The IDDMs made significantly more errors with the desaturated D15 compared with the control group (P < 0.05). The contrast sensitivity for the IDDMs was lower at each spatial frequency compared with the control group, being significantly different from 3 c/deg and above (P < 0.05). A negative correlation was found between HbA1 and contrast sensitivity at 6 and 12 c/deg; as the HbA1 increased the contrast sensitivity decreased (P < 0.05). As the blood glucose level decreased, the colour vision deteriorated (P < 0.05). There was no significant difference between the visual performance of those IDDMs with retinopathy (n = 5) compared to those without.

Adolescent↗

PubMedDate not supplied

[Physiotherapeutic correction of functional visual disturbances].

The authors describe a physiotherapeutic technique of functional stimulation of the organ of vision which allows effective prevention and correction of functional manifestations of visual asthenia syndrome in persons with normal visual status. The effectiveness of the technique was proved by improvement in clinical (sight acuteness, accommodation reserves), functional and subjective (visual life quality) parameters of the visual analyzer function.

Accommodation, Ocular↗

PubMed1998

Visual function in professional truck drivers.

OBJECTIVES: The purpose of this study was to examine the visual function of professional truck drivers at working age to find out whether older drivers had any defective function and should therefore be given less demanding duties at work. METHODS: Of the 100 drivers invited to the study, 77 came to the examination, including 74 men and 3 women aged from 30 to 66 years (mean 50.3+/-10.3 years). In addition to the basic eye examination, visual fields, dark adaptation, contrast sensitivity, color vision, and glare sensitivity were studied. RESULTS: Two drivers (2.6%) had an incipient cataract in one eye, four (5.2%) had slight fundus abnormalities, five (6.5%) had exo- or esotropia, and five (6.5%) had amblyopia. Visual acuity in the better eye varied from 0.4 to 1.2 (mean 1.06+/-0.17) and in the other eye from 0.1 to 1.2 (mean 0.96+/-0.23). Five drivers (6.5%) had inadequate visual acuity for a professional driver's license. Visual fields were interpreted as normal in all drivers. The results of the dark-adaptation, contrast-sensitivity, and glare testing showed values within normal ranges for all drivers. In the color-vision tests, five male drivers (6.8% of the men) had a slight congenital green defect, and two drivers had an acquired blue defect in one eye because of cataract and diabetes. CONCLUSIONS: According to the present study, there is no need to give older drivers less demanding duties because of their eyes. However, one serious finding in the present study needs attention: the visual acuity was lower than that required for a professional driver's license in five drivers. Evidently, more regular checkups of visual acuity are needed for a professional driver's license.

Adaptation, Ocular↗

PubMed1999

Validity of the visual function index (VF-14) in patients with retinal disease.

OBJECTIVE: To test the validity of the Visual Function Index (VF-14) in patients with retinal disease. DESIGN: A self-administered questionnaire package in association with clinical examination findings. PARTICIPANTS: Consecutive patients attending the Vancouver General Hospital Eye Care Centre, Vancouver, British Columbia, retina clinic between May 1 and August 15, 1998. MAIN OUTCOME MEASURES: Responses to the questionnaire package as they relate to global self-assessment scales and visual acuity. In addition, correlations were calculated between the VF-14, the 36-Item Short-Form Health Survey, a Weighted Comorbidity Scale, and visual acuity scores. RESULT: Five hundred forty-seven patients were given the questionnaire package to complete. The VF-14 demonstrated a moderately strong positive association with patient self-rating of amount of trouble, satisfaction, and overall quality of vision. Correlations between the 36-Item Short-Form Health Survey, visual acuity, and the global scales were mild to moderate. The VF-14 was moderately correlated with visual acuity in the better and the worse eyes. CONCLUSIONS: This study provides support for the validity of the VF-14 as a measure of functional impairment in patients with retinal disease. Once responsiveness has been measured and an analysis of disease subtypes has been carried out, the VF-14 will be ready for inclusion in clinical trials to evaluate patients' functional ability. Further implementation and development of this outcome measure will better our understanding of the utility of the functional assessment format for patients with retinal disease.

Adolescent↗

PubMed1992

Optic nerve decompression surgery improves visual function in patients with pseudotumor cerebri.

Papilledema from pseudotumor cerebri can cause severe loss of visual acuity and visual field. We performed optic nerve decompression surgery on 17 patients with pseudotumor cerebri who, despite maximum conventional therapy, developed progressive loss of visual acuity and/or visual field. Postoperatively, visual acuity improved or stabilized in 33 of 34 eyes (97%). Visual fields improved in 20 of 21 eyes that underwent surgery. Optic nerve decompression surgery relieves local cerebrospinal fluid pressure on the optic nerve. Progressive loss of visual function associated with pseudotumor cerebri can be reversed or stabilized with optic nerve sheath decompression surgery.

Adolescent↗

PubMed1990

Age-related maculopathy. I: A review of its morphology and effects on visual function.

Age-related maculopathy (ARM) is a leading cause of permanent vision loss in elderly people. ARM therefore constitutes an important public health problem which will increase in magnitude as the number of aged people in the general population becomes greater. The consequences of this condition are exacerbated by the fact that treatment, especially of the atrophic form of the disease, is ineffective. While laser photocoagulation may be helpful in the exudative form of ARM, there is often an inexorable progression towards severe vision loss in these patients. Therefore considerable attention needs to be paid to the aetiology of ARM, the potential for its prevention or delayed onset and its recognition through functional disturbances. This is the first of three papers dealing with ARM and its effects on visual function. We review its morphology and the visual disturbances that may ensue. The second and third papers will discuss the nature and detection of the central visual field loss due to ARM.

Aging↗

PubMed1999

Preliminary report: indications of improved visual function after retinal sheet transplantation in retinitis pigmentosa patients.

PURPOSE: To report indications of new visual function after retinal transplantation in two blind patients with retinitis pigmentosa. METHODS: Intact sheets of fetal retina (15 and 17 weeks gestational age) were transplanted subretinally (between the neurosensory retina and the retinal pigment epithelium) near the fovea in the left eye of a 23-year-old white man (Patient A) and in the left eye of a 72-year-old white woman (Patient B), both with autosomal-recessive retinitis pigmentosa. RESULTS: Postoperatively, at 6 and 5 months, respectively, both patients reported new visual sensation in the visual field corresponding to the transplant. In both patients, the visual sensation continued to be present after transplantation, at 12 and 8 months, respectively. In Patient A, a transient multifocal electroretinography (mfERG) response was observed in the transplant area 4 months postoperatively but was not detectable in Patient A at 6.0 and 9.5 months post-retinal transplantation. In Patient B, no positive mfERG responses were seen up to 5 months postoperatively. No rejection (presenting as cystoid macular edema, macular pucker, and extensive intraretinal edema with disrupted retinal pigment epithelium) to the transplanted tissue was seen up to 13 months in Patient A and 9 months in Patient B by fluorescein angiography. CONCLUSION: Transplantation of intact sheets of fetal human retina in two patients with retinitis pigmentosa was not associated with evidence of transplant rejection. Subjective improvement and an indication of objective improvement 4 months postoperatively were seen in Patient A, and subjective improvement only was seen in Patient B.

Adult↗

PubMed1996

Visual function of prematurely born children with and without perceptual-motor difficulties.

The relationship between visual and perceptual-motor abilities at 6 years of age was investigated in a cohort of 141 prematurely born children without cerebral palsy. Visual acuity was assessed using the Sonksen-Silver Acuity System and stereopsis with the Titmus stereo test. Perceptual motor abilities were evaluated using the Movement Assessment Battery for Children and the Developmental Test of Visual-Motor Integration. The results showed a higher incidence of abnormalities both of linear acuity and stereopsis in the study group when compared to a group of reference children. Whereas abnormalities of linear acuity were not associated with perceptual-motor difficulties, abnormal stereopsis was significantly associated with poor performance on both perceptual-motor tests. Our results suggest that infants born preterm, even in the absence of other major neurological signs, are at risk for abnormal visual function and perceptual-motor difficulties. As these could interfere with everyday life and school performance, a longitudinal assessment of both areas of competencies is recommended so that diagnosis and possible intervention can take place as early as possible.

Brain Diseases↗