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PubMed2006

Ethambutol-associated optic neuropathy.

INTRODUCTION: Ethambutol is used in the treatment of tuberculosis, which is still prevalent in Southeast Asia, and can be associated with permanent visual loss. We report 3 cases which presented with bitemporal hemianopia. CLINICAL PICTURE: Three patients with ethambutol-associated toxic optic neuropathy are described. All 3 patients had loss of central visual acuity, colour vision (Ishihara) and visual field. The visual field loss had a bitemporal flavour, suggesting involvement of the optic chiasm. TREATMENT: Despite stopping ethambutol on diagnosis, visual function continued to deteriorate for a few months. Subsequent improvement was mild in 2 cases. In the third case, visual acuity and colour vision normalised but the optic discs were pale. OUTCOME: All 3 patients had some permanent loss of visual function. CONCLUSIONS: Ethambutol usage is associated with permanent visual loss and should be avoided if possible or used with caution and proper ophthalmological follow-up. The author postulates that in cases of ethambutol associated chiasmopathy, ethambutol may initially affect the optic nerves and subsequently progress to involve the optic chiasm.

Aged↗

PubMed1995

Regeneration of specific nerve cells in lesioned visual cortex of the human brain: an indirect evidence after constant stimulation with different spots of light.

The defective parts of the visual field of two brain-injured patients were stimulated with different spots of light. There is evidence for at least five independent visual functions which can be restored due to constant stimulation of the blind part of the visual field: (1) The constant stimulation of the blind part of the visual field with spots of white light leads to an increase of the visual field for the perception of white light only. (2) The constant stimulation with spots of light of different wavelengths leads to an increase of the visual field for different color perception. To enlarge the visual field for the perception of the color red, a light stimulus with the wavelength of 656 nanometers (nm) was used; for the visual field for the perception of the color green 525 nm; for yellow 578 nm; and for blue 450 nm. (3) The constant stimulation of the blind visual field with black and white light bars of different orientations and constellations leads to an increase of the foveal acuity and an improvement of form perception in the periphery of the visual field. The results suggest that the recovery of visual functions, different color perception and form perception, may depend upon neuronal regeneration in the human visual cortex; regeneration occurs with adequate and constant stimulation of its specific neurons.

Adolescent↗

PubMed1994

Electrophysiologic alterations in patients with optic nerve hypoplasia.

The clinical and electrophysiologic data (electroretinograms and visual evoked potentials) were studied in 45 patients with optic nerve hypoplasia. The patients were divided into three fairly distinct groups on the basis of their electrophysiologic alterations. Group 1 consisted of 13 patients with almost extinguished visual evoked potentials and with mild electroretinographic alterations. These were the cases that are traditionally recognized as optic nerve hypoplasia. The serious visual impairment in these cases was accompanied by various developmental ophthalmologic and nonophthalmologic abnormalities. Group 2 included 26 patients without any significant visual evoked potential or electroretinographic alterations, but with overt funduscopic signs of optic nerve hypoplasia. These patients were consistently suffering from strabismus and/or amblyopia. The visual functions based on visual evoked potential and electroretinographic recordings could be fairly normal apart from a pathologic ophthalmoscopic picture characteristic of optic nerve hypoplasia. Group 3 included six patients with abnormal albeit well-recordable visual evoked potentials and subnormal or negative-type electroretinograms that suggested an accompanying retinal disease. This finding seems to prove that a subset of patients with optic nerve hypoplasia with nystagmus may have a primary retinal abnormality. Our study provides further evidence that optic nerve hypoplasia is not a uniform disease entity.

Adolescent↗

PubMed1988

Visual evoked potentials in tumors from orbita to occipital lobe in childhood.

68 infants and children with proven tumours along the visual pathway visually evoked potentials with pattern reversal and flash were investigated. Subdivided in 5 locational groups (orbital, optic nerve, chiasmatic, retrochiasmatic and occipital lobe) best results were obtained by stimulation with pattern reversal using variable checksizes (91.2%) versus 61.8% by using flash evoked responses. Furthermore, using patterned stimuli not only latency shifts are best detected but also hints for visual function correlating to visual acuity could be given also in nonverbal or disabled children. For long term follow-up studies in known space-occupying lesions along the visual pathway, the use of pattern VEP is extraordinary because of its high sensitivity and complete harmlessness. Pattern VEP are even more sensitive than visual acuity testing in cooperative patients. The close interdisciplinary follow-up controls in these children between pediatric neurophysiologists and neurosurgeons are, therefore, strongly recommended.

Adolescent↗

PubMed2005

Rehabilitation of hospital inpatients with visual impairments and disabilities from systemic illness.

OBJECTIVES: To describe the comorbidity of visual impairment and disability among patients hospitalized for systemic illness and to discuss rehabilitation. DESIGN: Retrospective study. SETTING: Hospital-based, academic tertiary medical center with referring neurology, ophthalmology, and rehabilitation units. PARTICIPANTS: Ninety-three hospitalized patients referred to the low vision rehabilitation clinic primarily by the physical medicine and rehabilitation and neurology units. INTERVENTIONS: Measurements of best-corrected visual acuity and other visual function testing. Referrals were made for prescriptive glasses, assistive devices, rehabilitation, resources, and ophthalmologic evaluation. MAIN OUTCOME MEASURES: Specialized services, presence of comorbidities, and visual function measurements. RESULTS: The mean admitting visual acuity revealed a moderate visual impairment. The primary diagnosis for admission (51%) was cerebrovascular accidents. There was a mean of 3.5 other comorbidities. CONCLUSIONS: The majority of patients admitted to the hospital for systemic diseases also had visual impairments. In many patients, this visual disability (either from the systemic and/or ocular disease) interfered with their activities of daily living.

Activities of Daily Living↗

PubMed2005

Cognitive, sensory and physical factors enabling driving safety in older adults.

We reviewed literature on cognitive, sensory, motor and physical factors associated with safe driving and crash risk in older adults with the goal of developing a model of factors enabling safe driving behaviour. Thirteen empirical studies reporting associations between cognitive, sensory, motor and physical factors and either self-reported crashes, state crash records or on-road driving measures were identified. Measures of attention, reaction time, memory, executive function, mental status, visual function, and physical function variables were associated with driving outcome measures. Self-monitoring was also identified as a factor that may moderate observed effects by influencing driving behavior. We propose that three enabling factors (cognition, sensory function and physical function/medical conditions) predict driving ability, but that accurate self-monitoring of these enabling factors is required for safe driving behaviour.

Accidents, Traffic↗

PubMed2001

Foveal translocation with scleral imbrication in patients with myopic neovascular maculopathy.

PURPOSE: To report our surgical results of foveal translocation with scleral imbrication in patients with myopic neovascular maculopathy. DESIGN: Noncomparative, interventional, consecutive case series. METHODS: Ten eyes of 10 myopic patients with subfoveal neovascular membranes that had undergone foveal translocation with scleral imbrication were recruited for this retrospective study. Inclusion criteria were myopia 6.0 diopters or greater in refractive error (or axial length 26.5 mm or longer), subfoveal choroidal neovascularization, and preoperative best-corrected visual acuity of 20/100 or worse. None of these eyes had undergone prior laser photocoagulation or submacular surgery. The main outcome measures were surgical complications and postoperative visual function. RESULTS: Postoperatively, visual acuity had improved more than 3 lines in the logarithm of minimum angle of resolution (logMAR) measurement in all eyes. The mean preoperative, postoperative best, and final visual acuity were 0.12, 0.59, and 0.51, respectively. Of the 10 eyes, six achieved a postoperative final visual acuity of 20/40 or better. The mean postoperative foveal displacement was 0.78 disk diameter (range, 0.3--1.3 disk diameter). Two patients underwent a reoperation because of insufficient foveal displacement. Furthermore, one of these two patients required a third operation to reduce an excessive retinal fold involving the fovea induced by the second surgery. Of the 10 patients, two noted transient diplopia. This complaint, however, resolved over time as suppression developed. Although unintentional iatrogenic retinal tears formed intraoperatively in two eyes, these were successfully treated without serious complications. Postoperatively, mild retinal pigment epithelial changes were observed in all cases, but none led to significant deterioration of visual acuity during the follow-up period. All patients but one were followed for a minimum of 6 months. CONCLUSIONS: In eyes with myopic neovascular maculopathy, foveal translocation with scleral imbrication may be useful in improving visual acuity. Further refinements in surgical technique and assessment of the long-term complications will be needed to make this procedure safer and more useful.

Adult↗

PubMed1998

Ophthalmological findings in patients with Takayasu disease.

We examined 65 (61 female and 4 male) Takayasu patients. Patient age ranged from 17 to 78 years old (mean 50.2); age of onset was from 11 to 60 years old (mean 32.8); and duration from onset to referral ranged from 1 month to 43 years (mean 16.8 years). Routine ophthalmological examinations were performed. Fluorescein angiography, kinetic perimetry by Goldmann perimetry, static perimetry by Octopus 1-2-3, electroretinography (ERG), and measurements of central retinal arterial pressure were also performed, as appropriate. Major causes of impaired visual acuity (less than 16/20) were cataract. A few patients had low visual acuity caused by Takayasu disease itself. On the other hand, although not many complained of visual disturbance, about 35% of patients had subnormal visual functions. Because the visual deterioration may be based on ocular hypoperfusion, which may subsequently lead to more serious changes, regular ophthalmological examination for every Takayasu disease patient is recommended.

Adolescent↗

PubMedDate not supplied

Long-term visual results in congenital cataract surgery associated with preoperative nystagmus.

BACKGROUND: Congenital cataracts are the leading cause of preventable blindness in children. The prevalence of this disease is higher in developing countries. The incidence and visual outcome of patients who have undergone congenital cataract surgery in Mexico is not currently known. The purpose of this study is to evaluate the long-term visual results in Mexican children with bilateral congenital cataracts associated with preoperative nystagmus. METHODS: In a tertiary-level hospital, the long-term visual results of 13 children (26 eyes) with bilateral congenital cataracts associated with preoperative nystagmus were evaluated. All patients had at least 5 years of follow-up after surgery, and all patients were subjected to an intentional ophthalmologic examination. Three types of visual function were evaluated: visual acuity, contrast sensitivity vision, and stereoscopic vision. Age at surgery was correlated with visual outcome. Optical rehabilitation and surgical complications were also analyzed. RESULTS: Our group found five patients (38%) with acceptable visual acuity levels. Eight patients (62%) were legally blind according to World Health Organization (WHO) guidelines. Contrast sensitivity vision and stereopsis were severely affected in all patients. We also found a high correlation between timing of surgery, optical rehabilitation, and visual outcome. CONCLUSIONS: Early diagnosis and treatment, in addition to adequate optical rehabilitation, are mandatory for preventing blindness secondary to congenital cataracts in developing countries. The current state of congenital cataract management in Mexico is also examined.

Adolescent↗

PubMed2000

Pit defects on the anterior surface of hydrophilic foldable intraocular lenses.

A series of pits varying in depth and size appeared on the anterior surface of hydrogel intraocular lenses (IOLs) soon after they were implanted. In all cases, the pits increased in size but not in number during a 1 year follow-up. The origin of the pit defects is unknown and does not seem related to inflammatory or lens epithelial cell activity. Hydration of the IOL could be a cause even if a manufacturing defect were present. This IOL surface alteration did not seem to impair visual function or cause visual disturbances.

Acrylic Resins↗

PubMed1998

Periventricular leukomalacia causes visual impairment in preterm children. A study on the aetiologies of visual impairment in a population-based group of preterm children born 1989-95 in the county of Värmland, Sweden.

PURPOSE: To determine the causes of visual impairment in a population-based group of visually impaired preterm children. METHODS: Ophthalmological examination and magnetic resonance imaging or computed tomography of the brain were performed in all visually impaired preterm children born 1989-95 in Värmland. RESULTS: Ten of 18 children had periventricular leukomalacia affecting the optic radiation, six had other lesions or malformations in the posterior visual pathways/cortex, but no child had visually impairing retinopathy of prematurity. CONCLUSION: We conclude that cerebral lesions or malformations are common causes of the visual functional deficit in visually impaired children born preterm. Brain damage should be suspected in a prematurely born child who presents with either of the signs: fixation difficulties, strabismus or nystagmus.

Adult↗

PubMed2002

[Rhegmatogenous PVR detachment: long-term results after extraocular minimal scleral buckling].

BACKGROUND: To present the long-term anatomical and functional results and the dynamics of proliferative vitreoretinopathy (PVR) after precise segmental scleral buckling without drainage, known as extraocular minimal surgery. PATIENTS AND METHODS: In a prospective study 172 consecutive rhegmatogenous PVR detachments were included which were operated on between January 1994 and February 1996 at the Department of Ophthalmology, Higher Medical Institute, Plovdiv, Bulgaria, with cryopexy and segmental scleral buckling without drainage. The follow-up ranged between 54 and 79 months (xmacr; 5S years). In 43 eyes was a PVR stage A, in 50 stage B, in 60 stage CP, and in 19 a PVR stage CA. All detachments were studied precisely for retinal breaks pre- and intraoperatively and the breaks tamponaded by a precise buckle. RESULTS: 1. Anatomical results: Complete retinal reattachment in 145 eyes (84 %) after 1 operation and in 148 eyes (86 %) after reoperation, residual tractional detachment with reattached macula in 12 eyes (7 %) and detachment due to progression of PVR in 12 eyes (7 %). 2. Functional results: Postoperative visual acuity ranged between 0.3 and 1.0 in 111 eyes after xmacr; 5S years. 3. Dynamics of PVR: In 113 detachments (65,7 %) PVR regressed completely and in 12 (7 %) it progressed; among these were 8 eyes with preoperative PVR-CA and 4 eyes with PVR-CP. CONCLUSIONS: Treatment of PVR detachments with nondrainage and minimal buckling provides good anatomical results with macular reattachment in 93 %, resulting in good long-term visual function. Results were best in detachments with PVR stage A, B and CP.

Adolescent↗

PubMed1995

[Congenital nystagmus in the ophthalmologic automobile driving fitness verdict].

BACKGROUND: A driver with congenital nystagmus (CN) is supposed to have a certain minimum visual acuity and a minimum velocity of reading, with the head directed straight ahead or 10 degrees laterally. The ability to perform different oculomotor tasks depends, however, on individual properties of nystagmus and compensatory mechanisms, as is demonstrated in 4 cases. METHODS: Detailed electrooculographic (EOG) recordings were performed in 4 CN patients, in addition to the examination of visual functions. RESULTS: The visual acuity of patient 1 is sufficient (0.6 on both eyes), yet his retinal image is intermittently destabilized by a periodic alternating nystagmus. Case 2 with high myopic astigmatism and severely reduced visual acuity (right eye: finger counting; left eye: 0.2) compensates for his vertical pendular nystagmus by head nodding and for his manifest-latent horizontal nystagmus by a head turn. The optimal visual acuity of patient 3 (horizontal pendular nystagmus) is 0.3, with an oblique head position and convergence. In other head and gaze positions he has a coarse jerk nystagmus beating in the direction of gaze. Patient 4, with a high myopic astigmatism, microstrabism and manifest-latent fixational nystagmus, has a visual acuity between 0.2 and 0.3 in both eyes. He had been a licensed professional car driver, in spite of contradicting national and international criteria: but his license was refused later. CONCLUSIONS: In patients with CN, the influence of head and gaze position, monocular fixation, convergence and self or object motion on nystagmus intensity and wave forms could be important for driving, because it might influence visual acuity and motion perception. The latter hypothesis still has to be proven in further studies, performed under conditions relevant for traffic.

Adult↗

PubMed2006

Consistent resting-state networks across healthy subjects.

Functional MRI (fMRI) can be applied to study the functional connectivity of the human brain. It has been suggested that fluctuations in the blood oxygenation level-dependent (BOLD) signal during rest reflect the neuronal baseline activity of the brain, representing the state of the human brain in the absence of goal-directed neuronal action and external input, and that these slow fluctuations correspond to functionally relevant resting-state networks. Several studies on resting fMRI have been conducted, reporting an apparent similarity between the identified patterns. The spatial consistency of these resting patterns, however, has not yet been evaluated and quantified. In this study, we apply a data analysis approach called tensor probabilistic independent component analysis to resting-state fMRI data to find coherencies that are consistent across subjects and sessions. We characterize and quantify the consistency of these effects by using a bootstrapping approach, and we estimate the BOLD amplitude modulation as well as the voxel-wise cross-subject variation. The analysis found 10 patterns with potential functional relevance, consisting of regions known to be involved in motor function, visual processing, executive functioning, auditory processing, memory, and the so-called default-mode network, each with BOLD signal changes up to 3%. In general, areas with a high mean percentage BOLD signal are consistent and show the least variation around the mean. These findings show that the baseline activity of the brain is consistent across subjects exhibiting significant temporal dynamics, with percentage BOLD signal change comparable with the signal changes found in task-related experiments.

Brain↗

PubMed2005

The effect of an ergonomic intervention on musculoskeletal, psychosocial and visual strain of VDT entry work: organization and methodology of the international study.

This special issue of the International Journal of Occupational Safety and Ergonomics (JOSE) reports the results from an extensive multinational and multidisciplinary collaborative investigation of the impacts on visual display terminal (VDT) work of musculoskeletal, visual, ergonomic, and psychosocial factors. For brevity, this effort has been referred to as the MEPS project (musculoskeletal--eyestrain--psychosocial--stress). This paper lays out the basic methodological structure of the study. The study was conducted in 4 countries utilizing VDT data entry workers as the primary subject population. A battery of objective and subject assessment measures, including muscle load, visual function, physical and visual strain, postural, ergonomic and psychosocial factors, were assessed at 3 different points in time. A pre-test was given prior to an ergonomic intervention. Two post-tests were given 1 month and 1 year after the ergonomic intervention.

Computer Terminals↗

PubMed1994

Epidemiology and screening of open-angle glaucoma.

Two major prevalence surveys for chronic open-angle glaucoma have been published in the last year. These are discussed in relation to the comprehensive Baltimore Eye Survey of 2 years ago, which also studied the blindness arising from the disease and comparative figures for white and black individuals. The newer tests for identification of loss of visual function prior to visual field loss as demonstrated by conventional automated perimetry are considered. The three main screening tests for chronic open-angle glaucoma--ophthalmoscopy, tonometry, and perimetry--are evaluated in the light of case finding experience in the United Kingdom. The maximum detection of asymptomatic early chronic open-angle glaucoma in the community is likely to be best achieved by a combination of public awareness of glaucoma aided by patient-based associations and the promotion of improved glaucoma testing and case finding by the army of professionals who are already in place in most developed countries and who carry out primary eye examinations.

Electroretinography↗

PubMed1976

Cysteine sulphinate decarboxylase in chick and rat retina during development.

The activity, properties and developmental pattern of cysteine sulphinate decarboxylase (CSD) were studied in chick and rat retina. Retinal CSD shows properties similar to those of the enzyme in brain with respect to optimum pH, saturating substrate concentrations and stimulation by pyridoxal phosphate, CSD activity increased 3-fold from the 10th day of embryogenesis to hatching in chicks and in postnatal development in rats. The developmental pattern of CSD activity in both species is coincident with the functional maturation of visual function.

Aging↗

PubMed2005

Modulatory effects of low- and high-frequency repetitive transcranial magnetic stimulation on visual cortex of healthy subjects undergoing light deprivation.

The aim of the present study was to explore further the effects of light deprivation (LD) on visual cortex excitability. Healthy subjects reporting reliable induction of phosphenes by occipital transcranial magnetic stimulation (TMS) underwent 60 min of complete LD. Phosphene threshold (PT) was measured before (T0), after 45 min (T1) and 60 min (T2) of LD, and then every 10 min after light re-exposure until recovery to T0 values. Repetitive TMS (rTMS) (at 1 or 10 Hz) was applied in separate sessions during the last 15 min of LD. PTs significantly decreased after 45 min of LD. rTMS differentially modified the effects of 60 min LD on PTs depending on stimulation frequency. One hertz rTMS did not change the decreasing of PT values as observed in baseline condition, but significantly prolonged the time to recover T0 PT values after light re-exposure. By contrast, 10 Hz rTMS significantly increased PT and the time to recover T0 PT values after light re-exposure was shortened. The results of this study show that the modulatory effects of different rTMS frequencies on visual cortex critically depend on the pre-existing excitability state of inhibitory and facilitatory circuits, and provide novel insights into the neurophysiological changes that take place in the visual cortex following functional visual deafferentation.

Adult↗