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PubMed2002

Aging and attentional guidance during visual search: functional neuroanatomy by positron emission tomography.

Positron emission tomography (PET) was used to examine adult age differences in neural activation during visual search. Target detection was less accurate for older adults than for younger adults, but both age groups were successful in using color to guide attention to a subset of display items. Increasing perceptual difficulty led to greater activation of occipitotemporal cortex for younger adults than for older adults, apparently as the result of older adults maintaining higher levels of activation within the easier task conditions. The results suggest that compensation for age-related decline in the efficiency of occipitotemporal cortical functioning was implemented by changes in the relative level of activation within this visual processing pathway, rather than by the recruitment of other cortical regions.

Adult↗

PubMed1988

Optic nerve sheath decompression for pseudotumor cerebri.

We studied optic nerve sheath decompressions for pseudotumor cerebri performed at the Kresge Eye Institute, Detroit, over the past year. Six patients (ten eyes) were operated on. Visual function improved in all ten eyes. A decision to operate was based on progressive loss of visual acuity or visual field unresponsive to medical therapy, accompanied by echographic evidence of a distended optic nerve sheath (positive 30 degrees test). Follow-up ranged from four to 11 months. Four patients underwent subarachnoid iopamidol (Isovue) contrast injection followed by orbital computed tomography. The subarachnoid space totally filled in all patients. No evidence of fibrosis or obstruction of the optic nerve sheath existed; however, leakage of dye from the optic nerve sheath could not be demonstrated. Postoperative complications included transient diplopia and transient atonic pupil (one patient each). Our results indicate that optic nerve sheath decompression improves and protects visual function in patients with pseudotumor cerebri who demonstrate progressive visual field loss and fluid in the optic nerve sheath.

Adult↗

PubMed2001

A double masked placebo controlled study on the effect of nifedipine on optic nerve blood flow and visual field function in patients with open angle glaucoma.

AIMS: To investigate whether nifedipine affects ocular perfusion or visual fields in open angle glaucoma patients. METHODS: In a parallel group study nifedipine or placebo was administered for 3 months (n = 30). Ocular fundus pulsation amplitude (FPA), cup blood flow (Flowcup) and visual field mean deviation (MD) were measured. RESULTS: Five patients receiving nifedipine discontinued due to adverse events. Nifedipine did not affect FPA [difference: 0.3 microm (95% CI -0.3,0.9); P = 0.70], Flowcup: [difference: -9 rel.units (95% CI -133,114); P = 0.99], or MD [difference: 0.2dB (95% CI -2.2,2.7); P = 0.51] vs placebo. CONCLUSIONS: Systemic nifedipine is not well tolerated in glaucoma patients and exerts no effect on visual fields or ocular perfusion.

Administration, Oral↗

PubMed1999

Integrated visualization of functional and anatomic brain data: a validation study.

UNLABELLED: Two-dimensional SPECT display and three methods for integrated visualization of SPECT and MRI patient data are evaluated in a multiobserver study to determine whether localization of functional data can be improved by adding anatomical information to the display. METHODS: SPECT and MRI data of 30 patients were gathered and presented using four types of display: one of SPECT in isolation, two integrated two-dimensional displays and one integrated three-dimensional display. Cold and hot spots in the peripheral cortex were preselected and indicated on black-and-white hard copies of the image data. Nuclear medicine physicians were asked to assign the corresponding spots in the image data on the computer screen to a lobe and a gyrus and give a confidence rating for both localizations. Interobserver agreement using kappa statistics and average confidence ratings were assessed to interpret the reported observations. RESULTS: Both the interobserver agreement and the confidence of the observers were greater for the integrated two-dimensional displays than for the two-dimensional SPECT display. An additional increase in agreement and confidence was seen with the integrated three-dimensional display. CONCLUSION: Integrated display of SPECT and MR brain images provides better localization of cerebral blood perfusion abnormalities in the peripheral cortex in relation to the anatomy of the brain than single-modality display and increases the confidence of the observer.

Cerebral Cortex↗

PubMed1998

[Congenital cataract extraction with intraocular lens implantation in children].

OBJECTIVE: To evaluate the results of cataract extraction with intraocular lens (IOL) implantation in children. METHODS: Cataract extracapsular extraction with anterior vitrectomy and IOL implantation was performed on 104 eyes of 64 children with congenital cataract aged 1.5 - 14 years old. The visual acuity and possible complications were followed up for a mean period of 22 months. RESULTS: After operation 86.4% patients were relieved from blindness, 62.7% obtained corrected vision >or= 0.3, binocular vision and stereopsis were restored in 41.8% and 30.6% respectively. In 3 eyes secondary cataract developed and in 5 eyes slight iris capture occurred. CONCLUSIONS: Cataract extraction with anterior vitrectomy and IOL implantation is effective in pediatric cataract treatment. Most patients get remarkable improvement in visual acuity and visual function with minimal complications after surgery. The influence factors on the postoperative visual function need further study.

Adolescent↗

PubMed1989

Integration of distributed cortical systems by reentry: a computer simulation of interactive functionally segregated visual areas.

A computer model based on visual cortex has been constructed to analyze how the operations of multiple, functionally segregated cortical areas can be coordinated and integrated to yield a unified perceptual response. We propose that cortical integration arises through the process of reentry--the ongoing, parallel, recursive signaling between separate maps along ordered anatomical connections. To test the efficacy of this reentrant cortical integration (RCI) model, we have carried out detailed computer simulations of 3 interconnected cortical areas in the striate and extrastriate cortex of the macaque. The simulated networks contained a total of over 222,000 units and 8.5 million connections. The 3 modeled areas, called VOR, VOC, and VMO, incorporate major anatomical and physiological properties of cortical areas V1, V3, and V5 but are vastly simplified compared with monkey visual cortex. Simulated area VOR contains both orientation and directionally selective units; simulated area VMO discriminates the direction of motion of arbitrarily oriented objects; and simulated area VOC responds to both luminance and occlusion boundaries in the stimulus. Area VOC is able to respond to illusory contours (Kanizsa, 1979) by means of the same neural architecture used for the discrimination of occlusion boundaries. This architecture also generates responses to structure-from-motion by virtue of reentrant connections from VMO to VOC. The responses of the simulated networks to these illusions are consistent with the perceptual responses of humans and other species presented with these stimuli. The networks also respond in a consistent manner to a novel illusion that combines illusory contours and structure-from-motion. The response synthesized to this combined illusion provides a strong argument supporting the need for a recursive reentrant process in the cortex. Functional integration of the simulated areas in the RCI model were found to depend upon the combined action of 3 reentrant processes: (1) conflicting responses among segregated areas are competitively eliminated, (2) outputs of each area are used by other areas in their own operations, and (3) outputs of an area are "reentered" back to itself (through lower areas) and can thus be used iteratively to synthesize responses to complex or illusory stimuli. Transection of the reentrant connections selectively abolished these integrative processes and led to failure of figural synthesis. The proposed model of reentry suggests a basis for understanding how multiple visual areas as well as other cortical areas may be integrated within a distributed system.

Animals↗

PubMed2002

Face recognition in age related macular degeneration: perceived disability, measured disability, and performance with a bioptic device.

AIMS: (1) To explore the relation between performance on tasks of familiar face recognition (FFR) and face expression difference discrimination (FED) with both perceived disability in face recognition and clinical measures of visual function in subjects with age related macular degeneration (AMD). (2) To quantify the gain in performance for face recognition tasks when subjects use a bioptic telescopic low vision device. METHODS: 30 subjects with AMD (age range 66-90 years; visual acuity 0.4-1.4 logMAR) were recruited for the study. Perceived (self rated) disability in face recognition was assessed by an eight item questionnaire covering a range of issues relating to face recognition. Visual functions measured were distance visual acuity (ETDRS logMAR charts), continuous text reading acuity (MNRead charts), contrast sensitivity (Pelli-Robson chart), and colour vision (large panel D-15). In the FFR task, images of famous people had to be identified. FED was assessed by a forced choice test where subjects had to decide which one of four images showed a different facial expression. These tasks were repeated with subjects using a bioptic device. RESULTS: Overall perceived disability in face recognition did not correlate with performance on either task, although a specific item on difficulty recognising familiar faces did correlate with FFR (r = 0.49, p<0.05). FFR performance was most closely related to distance acuity (r = -0.69, p<0.001), while FED performance was most closely related to continuous text reading acuity (r = -0.79, p<0.001). In multiple regression, neither contrast sensitivity nor colour vision significantly increased the explained variance. When using a bioptic telescope, FFR performance improved in 86% of subjects (median gain = 49%; p<0.001), while FED performance increased in 79% of subjects (median gain = 50%; p<0.01). CONCLUSION: Distance and reading visual acuity are closely associated with measured task performance in FFR and FED. A bioptic low vision device can offer a significant improvement in performance for face recognition tasks, and may be useful in reducing the handicap associated with this disability. There is, however, little evidence for a correlation between self rated difficulty in face recognition and measured performance for either task. Further work is needed to explore the complex relation between the perception of disability and measured performance.

Aged↗

PubMed1992

A randomized, controlled trial of corticosteroids in the treatment of acute optic neuritis. The Optic Neuritis Study Group.

BACKGROUND AND METHODS: The use of corticosteroids to treat optic neuritis is controversial. At 15 clinical centers, we randomly assigned 457 patients with acute optic neuritis to receive oral prednisone (1 mg per kilogram of body weight per day) for 14 days; intravenous methylprednisolone (1 g per day) for 3 days, followed by oral prednisone (1 mg per kilogram per day) for 11 days; or oral placebo for 14 days. Visual function was assessed over a six-month follow-up period. RESULTS: Visual function recovered faster in the group receiving intravenous methylprednisolone than in the placebo group; this was particularly true for the reversal of visual-field defects (P = 0.0001). Although the differences between the groups decreased with time, at six months the group that received intravenous methylprednisolone still had slightly better visual fields (P = 0.054), contrast sensitivity (P = 0.026), and color vision (P = 0.033) but not better visual acuity (P = 0.66). The outcome in the oral-prednisone group did not differ from that in the placebo group. In addition, the rate of new episodes of optic neuritis in either eye was higher in the group receiving oral prednisone, but not the group receiving intravenous methylprednisolone, than in the placebo group (relative risk for oral prednisone vs. placebo, 1.79; 95 percent confidence interval, 1.08 to 2.95). CONCLUSIONS: Intravenous methylprednisolone followed by oral prednisone speeds the recovery of visual loss due to optic neuritis and results in slightly better vision at six months. Oral prednisone alone, as prescribed in this study, is an ineffective treatment and increases the risk of new episodes of optic neuritis.

Acute Disease↗

PubMedDate not supplied

Bilateral visual loss and disc edema in a 15-year-old girl.

A 15-year-old girl with a ventriculoperitoneal shunt for congenital hydrocephalus presented with bilateral visual loss and disc edema. Although a CT scan showed no change in ventricular size, subsequent evaluation revealed elevated intracranial pressure and shunt malfunction. Initial visual loss was secondary to chronic papilledema. The rapid reduction of longstanding elevated intracranial pressure may have contributed to worsening of visual function after shunt revision. Subsequent optic nerve sheath fenestration did not improve visual function. In patients with treated hydrocephalus and symptoms of signs of raised intracranial pressure, shunt malfunction should be suspected even if neuro-imaging proves unremarkable.

Adolescent↗

PubMed2000

Retinal function in diabetic macular edema after focal laser photocoagulation.

PURPOSE: To assess the effects of focal photocoagulation on retinal function in the macular and perimacular areas in patients with diabetes who have clinically significant macular edema. METHODS: Eleven patients were assessed after focal laser treatment. Multifocal electroretinogram (ERG) and full-field ERG techniques were used to evaluate the effects of treatment on macular, paramacular, and peripheral retinal function. A modified visual field technique was used to obtain local threshold fields. The posttreatment results were compared with pretreatment results. Changes in local ERG response amplitudes and implicit times were calculated for each patient and presented as difference fields. The changes in local ERG responses were compared with the changes in local field sensitivity. RESULTS: After treatment, the results of the psychophysical tests suggested little or no change in visual function, but changes in retinal function were observed with the multifocal ERG technique. Local ERG responses showed increases in implicit time and decreases in amplitude, compared with pretreatment values. Timing was affected more than amplitude. CONCLUSIONS: The results suggest that focal treatment produces changes in retinal function, and these changes are not restricted to the treated macular area.

Adult↗

PubMed1993

Optic nerve sheath decompression may improve blood flow in anterior ischemic optic neuropathy.

PURPOSE: The purposes of this study are to evaluate the retrobulbar circulation in progressive nonarteritic ischemic optic neuropathy (NAION) and to assess changes in blood flow after optic nerve sheath decompression (ONSD). METHODS: Twenty-five patients with progressive NAION were studied using color Doppler imaging (CDI) before and after ONSD. Blood flow velocities and vascular resistance were calculated for the ophthalmic artery, central retinal artery, and posterior ciliary arteries in each eye. Contralateral eyes served as the control group. RESULTS: Preoperatively, the study group demonstrated significantly lower blood flow velocities in the central retinal artery (P < 0.002) and posterior ciliary arteries (P < 0.02) when compared with the contralateral control group. Postoperatively, there was a significant increase in blood flow velocity in the ophthalmic artery (P < 0.04) and the central retinal artery (P < 0.05) as well as a significant decrease in vascular resistance in the posterior ciliary arteries (P < 0.02) in the study group. There were no significant changes in blood flow velocity or vascular resistance in the contralateral control group. Long-term follow-up on eight patients suggests a persistence of this trend. Seventeen of the 25 operated eyes demonstrated a postoperative improvement in visual function, defined as a gain of two lines or more in Snellen visual acuity or at least 20 degrees of visual field expansion. CONCLUSIONS: These data demonstrate that eyes with acute NAION have impaired blood flow when compared with the contralateral control group. Furthermore, they suggest that ONSD may improve blood flow to the ischemic optic nerve halting the progression of visual loss and in some cases improving visual function.

Adult↗

PubMed2000

New low-contrast vision charts: reliability and test characteristics in patients with multiple sclerosis.

The quantitative assessment of visual function in multiple sclerosis (MS) clinical trials has been limited to Snellen visual acuity. The purpose of this study was to examine the inter-rater reliability and test characteristics of a new visual outcome measure, the Low-Contrast Sloan Letter Charts, in patients with MS and visually-asymptomatic volunteers. Contrast letter acuity scores (letter scores) were measured at each of four contrast levels (100, 5, 1.25 and 0.6%) by two independent raters. Inter-rater agreement was described with the intraclass correlation coefficient (ICC) and comparison of mean scores. Excellent inter-rater agreement (ICC=0.86 - 0.95) was demonstrated at each contrast level among MS patients (n=100) and visually-asymptomatic volunteers (n=33). Average letter scores at the lowest contrast level (0.6%) were highly variable in the MS group, even among patients with visual acuities of 20/20 or better, and among those who required no assistance for ambulation. Low-Contrast Sloan Letter Chart testing is a highly reliable method of visual assessment, and provides information on an aspect of neurologic impairment in MS which is not captured by Snellen visual acuity or ambulation status. This new method demonstrates excellent potential as a visual function outcome measure for future MS clinical trials.

Adolescent↗

PubMed2006

Retinal repair by transplantation of photoreceptor precursors.

Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors need only make single, short synaptic connections to contribute to the retinotopic map. So far, brain- and retina-derived stem cells transplanted into adult retina have shown little evidence of being able to integrate into the outer nuclear layer and differentiate into new photoreceptors. Furthermore, there has been no demonstration that transplanted cells form functional synaptic connections with other neurons in the recipient retina or restore visual function. This might be because the mature mammalian retina lacks the ability to accept and incorporate stem cells or to promote photoreceptor differentiation. We hypothesized that committed progenitor or precursor cells at later ontogenetic stages might have a higher probability of success upon transplantation. Here we show that donor cells can integrate into the adult or degenerating retina if they are taken from the developing retina at a time coincident with the peak of rod genesis. These transplanted cells integrate, differentiate into rod photoreceptors, form synaptic connections and improve visual function. Furthermore, we use genetically tagged post-mitotic rod precursors expressing the transcription factor Nrl (ref. 6) (neural retina leucine zipper) to show that successfully integrated rod photoreceptors are derived only from immature post-mitotic rod precursors and not from proliferating progenitor or stem cells. These findings define the ontogenetic stage of donor cells for successful rod photoreceptor transplantation.

Animals↗

PubMed2002

Levodopa-carbidopa with occlusion in older children with amblyopia.

PURPOSE: To study the role of levodopa-carbidopa in supplementing occlusion therapy in older children with strabismic or anisometropic amblyopia. METHODS: A clinical study was performed on 40 amblyopic children (19 strabismic and 21 anisometropic), 6 to 18 years old (mean age, 10.9 years). They received an average dose of 1.86 mg/kg/day (1.33-2.36 mg/kg/day) of levodopa and carbidopa (4:1 ratio) or a placebo in 3 divided doses over a 4-week period, combined with full-time occlusion. The occlusion was continued for the study duration of 3 months. Early Treatment Diabetic Retinopathy Study visual acuity charts and Cambridge low-contrast gratings for contrast sensitivity (CS) were used to assess visual functions. Tolerance and compliance with occlusion and capsule consumption were assessed. RESULTS: Visual acuity of the nonamblyopic eye did not deteriorate during the study in either group. CS decreased by 22 units in the levodopa group and increased in the placebo group by 53 units at the first month. The CS in the levodopa group recovered later by the third month of follow-up. Both the levodopa and the placebo groups showed significant improvement in visual function in the amblyopic eye (P <.001). Overall changes in logarithm of minimum angle of resolution values and CS in the amblyopic eyes were similar in both groups (P >.05). Strabismic and anisometropic amblyopes did not behave differently. Drug tolerance, occlusion compliance, and capsule ingestion compliance were similar between the groups, with no significant side effects. CONCLUSIONS: Clinically, levodopa supplementation does not offer any advantage over occlusion alone. Moreover, the risk of occlusion amblyopia could increase with the use of drugs like levodopa that might affect the plasticity of the visual cortex.

Adolescent↗

PubMed2003

Neuropsychological sequelae of exposure to welding fumes in a group of occupationally exposed men.

This study compares the neuropsychological function, emotional status, visual function, and illness prevalence of 76 former and current chemical industry welders primarily involved in steel welding, and exposed to welding fumes for an average of 24.9 years with that of 42 unexposed, non-welder controls. Health and occupational history questionnaires were administered, as were the neuropsychological tests included in the World Health Organization Neurobehavioral Core Test Battery, Luria Motor Test, and selected tests from the WAIS-III, and WMS-III. Emotional status tests included the BSI, POMS, BAI, and BDI, and vision tests included the Snellen near visual acuity, Lanthony d-15 color vision, Vistech Contrast Sensitivity, and Schirmer strips. While welders and controls performed similarly on tests of verbal skills, verbal retention, and auditory span, welders performed worse than controls on tests of verbal learning, working memory, cognitive flexibility, visuomotor processing speed, and motor efficiency. Welders had poorer color vision and emotional status, and increased prevalence of illnesses and psychiatric symptoms. The increased symptoms in welders were related to decreased scores on tasks measuring verbal learning, visuomotor abilities, visuospatial abilities, and information processing, and motor efficiency. Within the group of welders, the number of hours welding was negatively related to scores on verbal learning, auditory span, working memory, cognitive flexibility, and motor efficiency.

Adult↗

PubMed1998

Perception of movement and shape in Alzheimer's disease.

Alzheimer's disease is the most prevalent cause of abnormal cognitive decline in older adults and commonly affects visual function. Recent evidence suggests that Alzheimer's disease impairs the processing of visual motion, but these conclusions are based on conflicting results in the few cases studied, and the processing of complex motion images has not been investigated. In the present study of motion processing in Alzheimer's disease we assessed visual functions in 63 adults: 41 with mild to moderate Alzheimer's disease (mean age 72.3 years) and 22 without dementia (mean age 71.7 years). Processing of motion cues was tested with computer animation sequences known as random-dot cinematograms, which resemble the stimuli used to define motion processing deficits in primates with lesions of cortical area MT. Results showed that participants with Alzheimer's disease required significantly greater thresholds for perceiving shapes defined by motion cues compared with participants without dementia (P = 0.0005). There were no significant differences between the two groups (P < 0.05) in static visual acuity, static spatial contrast sensitivity and, surprisingly, dynamic visual acuity, which was normal, and motion direction discrimination, which was relatively spared. We conclude that mild to moderate Alzheimer's disease has significant effects on the perception of structure from motion with relative sparing of motion direction discrimination. We cannot exclude a contribution by retinal pathology, but retinal dysfunction alone cannot explain the pattern of defects we observed. The complex motion image processing deficit we identified is likely to have a cerebral basis and has the potential to affect navigation and the recognition of objects in relative motion, as encountered during walking and automobile driving.

Aged↗

PubMed1994

Effect of methazolamide on chronic macular edema in patients with retinitis pigmentosa.

PURPOSE: To determine the effectiveness of methazolamide for improving visual acuity and macular edema in patients with retinitis pigmentosa. METHODS: Seventeen subjects with retinitis pigmentosa and chronic macular edema participated in a prospective, placebo-controlled, double-masked, crossover design study in which either methazolamide or a placebo was taken for 3 weeks. Visual acuity, fluorescein angiograms, and subjective impressions were obtained at baseline and after 3 weeks of treatment with each substance. A subgroup of subjects were enrolled in a more extended period of methazolamide treatment for an additional 3 months. RESULTS: Methazolamide resulted in the improvement of angiographic macular edema in 9 of 17 subjects. As a group, visual acuity statistically improved with methazolamide. However, improvement in at least one eye, of between two and four lines more than while taking placebo, occurred in only three (undilated pupils) or four (dilated pupils) subjects. Subjective improvement during treatment with methazolamide but not placebo occurred in only one subject. An extended period of methazolamide treatment for an additional 3 months in a subgroup of patients did not result in additional beneficial effects on visual acuity. In fact, a partial rebound in the extent of macular edema was found. CONCLUSIONS: Although angiographic improvement of macular edema can occur in patients with retinitis pigmentosa treated with methazolamide, notable (between 3 and 4 lines) or even moderate (between 2 and 3 lines) visual acuity improvement was seen in relatively few patients. When methazolamide was administered in a placebo-controlled fashion, subjective improvement in visual function also was not readily apparent. A more substantial subjective improvement in visual function had occurred with the use of acetazolamide in five of six subjects who also had participated in a previous treatment trial with the use of acetazolamide.

Adolescent↗

PubMed2003

Development of the National Eye Institute refractive error correction quality of life questionnaire: focus groups.

OBJECTIVE: To identify the content area for a questionnaire designed to measure the vision-targeted, health-related quality of life for persons with well-corrected refractive error. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-two focus groups were conducted with 414 patients from 5 geographically diverse ophthalmic and optometric sites to identify the content area of a questionnaire for use among persons with myopia and hyperopia. METHODS: A standard protocol was used to structure each focus group discussion, and groups were led by centrally trained moderators at each participating site. Results were summarized and analyzed using a standard set of codes. Qualitative and quantitative analyses were conducted. MAIN OUTCOME MEASURE: Self-reported observations or comments about vision, vision correction, and other aspects of quality of life. RESULTS: Among the 414 participants, 9262 mentions of comments were recorded. The most frequent comments reported by participants were about types of vision correction, followed by comments with their own vision and vision-related symptoms. The distribution of comments by topic domain was generally similar across types of correction and type of refractive error. The most frequent specific comments about glasses concerned problems with reading, adjustment between near and far vision, and appearance. The most frequent comments about contact lenses included those on symptoms such as dry eyes, itching and tired eyes, and headaches, and negative comments about ease of use. The most frequent comments among patients with surgical correction concerned fewer driving problems; fewer symptoms; and improvement in vision, recreation, and comfort. Participants provided equal numbers of positive and negative comments about glasses. Twice as many positive as negative comments were given by contact lens wearers, and 4 times as many positive comments were provided by patients who had undergone surgical correction. CONCLUSIONS: Using focus groups, we were able to identify content areas and aspects of visual functioning in persons with refractive error that are not measured by standard visual acuity testing in the clinic or by other vision-targeted, health-related quality of life instruments such as the 25- or 51-item National Eye Institute-Visual Functioning Questionnaire. The similarity of problems mentioned across refractive error type and correction method suggests it will be possible to develop a single questionnaire with adequate content validity to compare the impact of different modes of correction in vision-targeted, health-related quality of life.

Adult↗