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Peculiarities of drivers' work require visual strain. The studies prove considerable changes in accommodation (value of absolute and resources of relative accommodation), muscular balance, visual performance in correction test, that prove visual fatigue of automobile drivers, especially aged 20 to 30.
BACKGROUND: The care of indirect traumatic optic neuropathy is still treated differently. Special diagnostic and therapeutic difficulties exist in comatose patients without definable visual acuity and in patients with complex failure of the visual field with central visual acuity still receiving sufficiently. METHOD: The total collective of optic nerve decompressions within the period between January 1992 and August 2000 was comprised of 66 patients. 18 of these 66 patients (average age: 40.5 years) were comatose and required critical care. 3 of the 48 consciousness-clear patients showed post-traumatically different defects of the visual field with a visual acuity of 0.3, 0.4 and 1.0. The indication for surgical decompression in both groups was based on the ophthalmological findings and the CT-finding of traumatization of the optic nerve, or the orbit apex respectively. RESULTS: During the subsequent postoperative examinations (on average 12.3 months postoperatively) five patients within the group of the unconscious patients showed a normal visual acuity (0.9-1.0), 3 patients a visual acuity of 0.7, 0.4 and 0.3 and one a visual acuity of 0.1. Six patients remained amaurotic. Three patients died from the general consequences of injury. Improvement of visual field and correction of stereoscopic function occurred in all patients, operated on primarily because of the described visual defects. CONCLUSIONS: Due to these results the indication for the decompression of the optic nerve should find special consideration in comatose patients and in cases of severe restriction of the visual field.
Long-term scotopic (rod-mediated) visual deficits following developmental lead exposure occur in monkeys and hooded rats. This report describes and summarizes previous ERG and biochemical findings, presents new biochemical data aimed at determining the mechanism of inhibition of lead on rod cGMP-PDE, presents an integratory framework for understanding the ERG and cGMP results and speculates on the implications of the present data. A- and b-wave voltage-log intensity and latency-log intensity functions, generated from single-flash ERGs in fully dark-adapted rats, revealed that low and moderate level lead exposure caused decreases in absolute sensitivity and amplitude, and increases in latency. Rod- and cone-mediated flicker fusion frequency measures revealed selective rod deficits in temporal resolution. In addition, the slope of the increment threshold function was decreased, but only at scotopic adapting backgrounds, and dark adaptation was delayed. Prior exposure to lead produced a dose-response inhibition of retinal cGMP-phosphodiesterase (PDE) resulting in an increase in cGMP in dark-adapted and light-adapted states and an increase in the calcium content of rods. In vitro experiments with adult rat retinas incubated with 10(-9) to 10(-4) M Pb2+ revealed a concentration-dependent inhibition of cGMP-PDE which suggested that Pb2+ directly inhibited the rod cGMP-PDE. This was confirmed in experiments conducted with isolated, purified, trypsin-activated bovine rod cGMP-specific PDE exposed to 5 x 10(-8) to 10(-4) M Pb2+. The cGMP data are entirely consistent with the observed ERG changes. The ERG data is relevant to low level pediatric lead poisoning since rat rods are similar to human rods. Finally, since a lesion in the gene that codes for a cAMP-PDE leads to defective learning and memory in the Drosophila dunce flies, it is possible that lead-induced alterations in cyclic nucleotide phosphodiesterases contribute to the long-term CNS deficits produced by developmental lead exposure.
The essential role of the primary visual cortex in visual processing has been extensively studied over the last century or more. Injuries to the visual cortex in adult humans can produce blindness, referred to as "cortical blindness". In children some degree of visual recovery has been noted in comparable injuries and for that reason the term "cortical visual impairment" has been suggested as a more appropriate diagnosis in children. This term is, however, inaccurate as a significant number of children with visual loss and neurologic damage have injuries to the noncerebral pathways (for example--optic radiations in children with periventricular leukomalacia). In this study we compare visual outcomes and recovery in children with primary visual cortex lesions vs those with periventricular leukomalacia. We suggest that the poorer outcomes of children with periventricular leukomalacia could have been predicted based on studies of the mechanisms of visual recovery in infant animals following visual cortex ablation.
The recovery of visual disturbances provoked by partial neocortical deafferentation was studied in dogs with two sets of visual patterns: figures and differently oriented lines. The disturbances were more prominent, when the dogs had to solve the most complex visual tasks (6 stimuli showed to a dog simultaneously). There was a distinct recovery of figure recognition in the process of compensation, i. e. in 4--6 months after the neocortical deafferentation. On the contrary, recognition of oriented lines did not improve. Probably the differences between the two sorts of recognition mentioned above may be explained by various changes of their mechanisms' properties in the process of compensation.
Recent research has identified a low-level transient visual system deficit in patients with reading disability. This deficit has been shown to have consequences on higher level perceptual and cognitive functions, including reading. This new information provides optometrists with a theoretical framework to expand the understanding of the relationship between vision and reading. In this paper, traditional concepts are described and an extensive literature review is provided. The impact of these processing deficits on reading performance is discussed based on metacontrast masking and foveal-parafoveal sequential attention models of reading. Clinical implications of transient system function in other clinical entities are also provided.
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OBJECTIVE: To compare visual acuity, optic disc appearance, and transient pattern reversal visual evoked potentials as markers of possible visual dysfunction in children with syndromic craniosynostosis. METHODS: Serial visual acuity, optic disc appearance, and pattern reversal visual evoked potential data were recorded in 8 patients with syndromic craniosynostosis before and after cranial vault expansion. The pattern reversal visual evoked potentials were analyzed using linear regression modeling, applied to the N80 to P100 amplitude. RESULTS: Serial optic disc appearances were available for all 8 patients and visual acuities for 7 patients. The visual acuity deteriorated in only 1 patient, improved in 4, and fluctuated in 2, before surgery. Of the 8 patients, 3 showed no papilledema in either eye at any time, 3 showed progressive bilateral swelling before surgery, and 2 exhibited only unilateral disc swelling. In all 8 patients, there was a trend for the N80 to P100 amplitude to decrease before surgery and to increase, in all but 2 patients, after surgery. CONCLUSIONS: This study suggests that neither optic disc appearance nor visual acuity assessment alone is a reliable marker of potential visual dysfunction in children with syndromic craniosynostosis. It also suggests that the pattern reversal visual evoked potential can provide early evidence of visual dysfunction before vault expansion surgery in these children; this dysfunction may recover postoperatively.
Twenty myopic adults were randomly assigned to either a behavioral visual acuity training program or to a no-treatment control group in order to assess changes in several aspects of visual behavior. Measures were obtained both pre- and posttraining for a number of variables. These included recognition and resolution visual acuity, contrast sensitivity, perceived clarity and confidence of responses, and stimulus duration. Results indicated that training subjects significantly improved on all three measures of visual acuity: recognition acuity, resolution acuity, and contrast sensitivity. Improvements in acuity were associated with significant improvements in the perceived clarity of the stimuli but not in the confidence of the subject's response. These data expand our knowledge concerning the effectiveness of behavioral training programs in improving visual acuity in myopia. The potential utility of such programs is discussed.
PURPOSE: To compare best-corrected visual acuity (BCVA) and contrast sensitivity (CS) under different levels of illumination in patients who had monofocal and multifocal intraocular lenses (IOLs) and to establish the effect of different lighting conditions on vision in the two groups of patients. METHODS: We retrospectively reviewed 27 patients who underwent phacoemulsification for age-related cataract and IOL implantation of either monofocal (SI30NB; n=10, 37%) or multifocal (SA40N; n=17, 63%) IOLs. Binocular distance and near BCVA and CS were tested using logMAR and Pelli-Robson charts that were externally illuminated with 20, 200, 400, and 1600 lux, and were compared using repeated-measures analysis of variance. A questionnaire was administered to establish the lighting preference in the two groups and the effect of lighting conditions on their vision. RESULTS: Binocular distance and near BCVA and CS significantly increased with increasing illumination from 20 to 200 lux in the monofocal (mean=0.04 vs -0.07; P=0.006; 0.37 vs 0.26, P=0.002 and 1.47 vs 1.60, P=0.01) as well as in the multifocal group (mean=0.03 vs -0.12, P<0.001; 0.38 vs 0.23, P<0.001 and 1.47 vs 1.61, P=0.002). No significant difference in BCVA or CS was found between the two groups at any of the four illumination levels. Both groups had similar lighting preference, but 43.8% of patients in the multifocal group experienced subjective worsening of their vision in bright outdoor lights. CONCLUSIONS: Distance and near BCVA and CS improve with increasing illumination in patients with monofocal and multifocal IOLs, but remain comparable in the two groups under common levels of indoor illumination. Patients with multifocal IOLs may experience worsening of their vision in bright outdoor lights.
PURPOSE: We compare the contrast sensitivity and visual acuity obtained with an anterior surface modified prolate intraocular lens (Tecnis Z9000) with the contrast sensitivity and visual acuity obtained with a standard acrylic foldable intraocular lens (Acrysof SA60 AT). METHODS: In this prospective trial, 64 patients presenting for cataract surgery were randomized to receive in both eyes either the Tecnis Z9000 intraocular lens or the the Acrysof SA60AT intraocular lens: 32 Tecnis Z9000 and 32 Acrysof SA60AT. Visual acuity and contrast sensitivity were monocular and binocularly tested in all of them preoperatively and three months after surgery. RESULTS: The Tecnis Z9000 intraocular lens provided statistically significantly better monocular (Tecnis group: 0.85; Acrysof group: 0.78; p < 0.01) and binocular (Tecnis group: 0.95; Acrysof group: 0.86; p < 0.02) visual acuity. The contrast sensitivity mean was also greater in Tecnis group in monocular and binocular conditions, but without statistical signification. CONCLUSION: Visual acuity and contrast sensitivity after cataract surgery improved in both groups. But monocular and binocular visual acuity was statistically significantly better only in Tecnis group. The contrast sensitivity mean values were greater in Tecnis group but without statistically significant differences.
Many neurologic disorders cause acute or chronic hydrocephalus. Visual loss, diplopia, cranial nerve palsies, strabismus, and papilledema suggest hydrocephalus. Evaluation of these signs and symptoms aid in determining the etiology of the hydrocephalus.
Careful evaluation of all parameters of ocular function are required to delineate the cause of lack of visual responses in children. Any visual fixation, no matter how fleeting, is a sign of intact visual pathways. If no sign of ocular pathology can be found on the routine exam of the visually inattentive child, electrophysiologic testing may be necessary to confirm the presence of abnormality of the visual pathways. In the child with a generalized CNS disorder, the lack of visual response may be due to his inability to respond to visual information (perceptual blindness) rather than to organic pathology in the occipital cortex (cortical blindness).
SUMMARY: The Evolutionary Trace Viewer (ETV) provides a one-stop environment in which to run, visualize and interpret Evolutionary Trace (ET) predictions of functional sites in protein structures. ETV is implemented using Java to run across different operating systems using Java Web Start technology. AVAILABILITY: The ETV is available for download from our website at http://mammoth.bcm.tmc.edu/traceview/index.html. This webpage also links to sample trace results and a user manual that describes ET Viewer functions in detail.
PURPOSE: To assess functional and anatomical outcomes after foveal translocation with 360-degree retinotomy and simultaneous torsional muscle surgery in patients with myopic neovascular maculopathy. METHODS: Foveal translocation with 360-degree retinotomy was performed in 11 eyes of 11 patients with myopic neovascular maculopathy. Ten eyes had simultaneous torsional muscle surgery with recession of the superior oblique muscle and tucking of the inferior oblique muscle. Silicone oil removal with or without intraocular lens implantation was performed 2 to 8 weeks after the primary procedure. Visual acuity, binocular function, and degree of cyclotorsion were assessed preoperatively and postoperatively. Angles of retinal and globe rotation, distance of foveal shift, and surgical complications were also investigated. RESULTS: With a mean postoperative follow-up of 6.2 months (range, 3 to 13 months), vision improved (greater than 0.2 logarithm of minimal angle of resolution [logMAR] units) in eight eyes, was unchanged in two eyes, and worsened (greater than 0.2 logMAR units) in 1 eye. Seven of 11 eyes (64%) had a final visual acuity of 20/50 or better. Five patients developed or maintained binocular fusion, four patients continued to have suppression, and two patients developed diplopia that was managed by spectacles with Fresnel prisms. Subjective cyclotorsion was less than 8 degrees in 10 eyes. Mean retinal and globe rotations were 23.4 degrees and 19.8 degrees, respectively. Average size of the choroidal neovascular membrane was 0.8 disk diameter, whereas the average distance of foveal shift was 1.5 disk diameter. After the primary procedure, three eyes developed retinal detachment, one eye macular hole, and one eye proliferative vitreoretinopathy. These complications were successfully managed by additional surgery. CONCLUSION: Foveal translocation with 360-degree retinotomy is effective in restoring vision in some patients with myopic neovascular maculopathy. Although the development of torsional diplopia is generally obviated by simultaneous extraocular muscle surgery, a relatively high incidence of surgical complications should be taken into account with this procedure.
PURPOSE: Premature infants are at increased risk of impaired visual performance related to both cortical and subcortical pathways for oculomotor control. The hypothesis for the current study was that preterm infants with impaired saccades, smooth pursuit, and binocular eye alignment at age 2 years would have smaller occipital brain volumes at term equivalent, as measured by volumetric magnetic resonance (MR) techniques, than would preterm infants without such abnormalities. METHODS: Study participants consisted of 68 infants from a representative regional cohort of 100 preterm infants born between 23 and 33 weeks' gestation. At term equivalent, all infants underwent MR imaging, and the images were coregistered, tissue segmented into five cerebral tissue subtypes, and further subdivided into eight regions for each hemisphere. At 2 years corrected, all infants completed a comprehensive orthoptic evaluation performed by a single examiner. RESULTS: Twenty-four (35%) of the 68 infants had abnormal oculomotor control at 2 years, including abnormalities in saccadic movements (n = 7), smooth pursuit (n = 14), or strabismus (n = 9, four with esotropia and five with exotropia). When compared with preterm infants without visuomotor impairment, these infants had significantly smaller inferior occipital region brain tissue volumes bilaterally (n = 24 vs. n = 44; total tissue, mean +/- SD, left, 37.9 +/- 7.4 cm(3) vs. 43.7 +/- 7.4 cm(3); mean difference [95% CI] -5.7 [-9.4 to -2.0] cm(3), P = 0.003; right, 36.8 +/- 7.1 cm(3) vs. 41.4 +/- 6.2 cm(3), mean difference -4.6 [-7.9 to -1.3] cm(3), P = 0.007). This difference remained significant after adjusting for intracranial volume (ICV; left, mean difference -3.5 [-6.7 to -0.2] cm(3), P = 0.04; right, mean difference -2.4 [-5.2 to -0.4] cm(3), P = 0.09). Within this region, the cortical gray matter volume was the most significantly reduced (left, 20.4 +/- 6.2 cm(3) vs. 25.4 +/- 5.6 cm(3), mean difference -3.1 [-5.7 to -0.5] cm(3), P = 0.02; right 21.0 +/- 5.4 cm(3) vs. 24.9 +/- 5.0 cm(3), mean difference -2.2 [-4.4 to 0.0] cm(3), P = 0.05, ICV adjusted). Abnormalities in saccadic eye movements accounted for the largest effect on inferior occipital regional brain volumes (left side, P = 0.02). CONCLUSIONS: Volumetric MR imaging techniques demonstrated an overall reduction in the inferior occipital regional brain volumes in preterm infants at term corrected who later exhibit impaired oculomotor function control. These findings assist in understanding the neuroanatomic correlates of later visual difficulties experienced by infants born prematurely.
PURPOSE: To investigate whether initial valproate (VPA) monotherapy for the treatment of epilepsy causes visual field defects and visual dysfunction. METHODS: In a cross-sectional study, visual fields were examined with the kinetic Goldmann and automated Humphrey perimeters, contrast sensitivity function with the Pelli-Robson letter chart and colour vision with the Standard Pseudoisochromatic Plates Part 2 (SPP 2) and Farnsworth-Munsell 100 Hue test (FM 100) in eighteen epilepsy patients (aged 18--50 years, 30.2.+/-10 years, mean+/-S.D.) treated with initial valproate monotherapy for 2--20 years (8.4+/-5.1 years). RESULTS: None had vigabatrin-type, concentric visual field defect with the kinetic Goldmann or automated Humphrey perimetries. In the Humphrey perimetry, the mean deviation for the group was within normal limits varying from -2.53 to 0.59 dB (-0.74+/-0.80 dB) in the right eye and from -2.66 to 0.67 dB (-0.78+/-0.82 dB) in the left eye. In the FM 100 test, acquired colour vision deficiency was found in two out of 18 patients (11%, 95% CI: 0--25%). However, the mean total error score was lower in the patient group than in the control group. All patients had normal contrast sensitivity function. CONCLUSIONS: The use of VPA in the treatment of epilepsy is not associated with visual field defects similar to vigabatrin, but may induce abnormalities in colour vision.
PURPOSE: To evaluate retinal sensitivity and fixation patterns in patients with Best's dystrophy by microperimetry (MP) and to correlate the results with static perimetry and retinal morphology seen by autofluorescence (AF). METHODS: Central 10 degrees visual fields in 11 patients with Best's dystrophy (VA: 0.5+/-0.38) were recorded by the Octopus M2 TOP program and by MP (MP1, Nidek Technologies). AF was recorded by HRA (Heidelberg Engineering). RESULTS: High correlation (R=0.75, -0.76, -0.48) was found between static perimetry (MS, MD and CLV indices) and MP. Based on MP and AF results, three groups of patients were formed. Patients in the first two groups fixated inside the central nonuniform hypo- and hyperfluorescent AF ring area, next to relative (Group 1) or absolute scotoma (Group 2). Inner parts of the retina close to the fovea were most affected, whereas regions closer to the periphery of the 10 degrees visual field showed near normal function. As the disease progressed, there was an evident shift of fixation to preferential retinal locus (PRL) in eight eyes with visual acuity 0.2 or less (Group 3). Fixation shift was superior in four eyes, temporal in two eyes, and nasal in two eyes. CONCLUSION: MP enabled a highly sensitive topographic monitoring of retinal function, showing central or pericentral fixation in the early stages, until loss of central function, in eyes with VA 0.2 or less, caused evident shift of fixation to PRL. PRL was never situated inside the central uniform hypofluorescent area, but corresponded with the hyperfluorescent ring seen with AF imaging.