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PubMed2003

Central and peripheral vision loss associated with nefazodone usage.

A 35-year-old woman who reported persistent significant vision loss for 3 years after taking the antidepressant nefazodone was referred for electrophysiological assessment of vision. The vision changes included reduced acuities, reduced colour vision and visual field constriction in both eyes and were thought to be associated with the use of nefazodone for 6 - 8 weeks, 3 years earlier. Multifocal electroretinograms and visual evoked potentials were recorded using the Visual Evoked Response Imaging System (VERIS) to investigate the nature and site of the neural deficit. The summed retinal response showed a normal a- and b-wave latency and amplitude, however, the retinal topographic mfERGs showed a severe depression of the macular response in both eyes. The cortical topographic multifocal VEP mapping also showed a central depression in the right eye compared with the left. Two-frame motion and pattern custom mfVEP were also measured to assess different forms of cortical processing and especially of motion as nefazodone has previously been associated with image persistence with moving stimuli. The responses to two frame-motion showed signs of abnormality. Thus these results suggest that the primary locus of neural damage is retinal and is likely to have resulted from neurotoxicity. Other competing hypotheses such as hysterical blindness must be ruled out.

Adult↗
PubMedDate not supplied

Loss of spatial phase relationships in extrafoveal vision.

Objects in peripheral vision are not simply blurred but lack quality of form. Assuming that the visual system performs a (patchwise) Fourier analysis of the retinal image (for review see ref. 2), it has been suggested that this disadvantage of peripheral vision may be due to the inability to encode properly spatial phase relationships. This is of great interest for neurological research as certain visual pathologies imply alterations of perceived form. Previous attempts at measuring phase sensitivities failed to distinguish between the detection of phase-related changes in contrast and phase coding in the visual system. We separated these processing strategies by applying the iso-second-order texture paradigm of Julesz to the discrimination of compound gratings. Our results, reported here, show that the energy detection properties of both foveal and peripheral vision are comparable, however, independently of scale, peripheral vision ignores the relative position of image components.

Fovea Centralis↗
PubMed1988

A unique colour and polarization vision system in mantis shrimps.

The apposition compound eyes of mantis shrimps (stomatopods) are divided into three sections, the dorsal and ventral hemispheres and the midband. Many ommatidia of both hemispheres, and all those in the midband, sample the same narrow band in space. The function of the morphologically distinct midband region is not clear, but new evidence suggests that it may be adapted in a unique manner for colour and polarization vision. A series of carotenoid colour filters screen the photopigment and potentially provide a tetrachromatic input for contrast-enhanced vision or true colour vision. The filters are blocks of coloured droplets (red, orange, yellow, purple, pink or blue) within the rhabdoms of two rows of midband ommatidia. The arrangement of tiered microvilli in two other midband rows suggests that they provide a unique form of polarization vision.

Animals↗
PubMed1999

Position of a 'green-red' hybrid gene in the visual pigment array determines colour-vision phenotype.

The X-linked red- and green-pigment genes are arranged in a head-to-tail tandem array. The colour-vision defect of deuteranomaly (in 5% of males of European descent) is associated with a 5'-green-red-3' visual-pigment hybrid gene, which may also exist in males with normal colour vision. To explain why males with a normal red, a normal green and a green-red hybrid gene may have either normal or deutan colour vision, we hypothesized that only the first two genes are expressed and deuteranomaly results only if the green-red hybrid gene occupies the second position and is expressed preferentially over normal green-pigment genes occupying more distal positions. We used long-range PCR amplification and studied 10 deutan males (8 deuteranomalous and 2 deuteranopic) with 3 visual pigment genes (red, green and green-red hybrid) to investigate whether position of the hybrid gene in the array determined gene expression. The green-red hybrid gene was always at the second position (and the first position was always occupied by the red gene). Conversely, in two men with red, green and green-red hybrid genes and normal colour vision, the hybrid gene occupied the third position. When pigment gene mRNA expression was assessed in post-mortem retinae of three men with the red, green and green-red genotype, the green-red hybrid gene was expressed only when located in the second position. We conclude that the green-red hybrid gene will only cause deutan defects when it occupies the second position of the pigment gene array.

Color Perception↗
PubMed1989

Poor vision and the elderly--a domiciliary study.

Thirty-four patients living in Norfolk, aged 65 years and over, with visual acuities between 6/60 and counting fingers were interviewed at home to ascertain the degree of their disability and their use of low vision aids. Visual acuity in this range was not associated with patients' mobility or their dependence on others. A threshold of useful vision could not be identified within this range. Use of low vision aids, although disappointing, was more frequent by those who had attended a low vision clinic.

Activities of Daily Living↗
PubMed1998

The effect of anthocyanosides on night vision.

PURPOSE: In view of research demonstrating the ability of anthocyanosides in a single oral dose to improve night vision in normal individuals, it was decided to evaluate their effect on three night vision tests: full-field scotopic retinal threshold (SRT), dark adaptation rate (DAR) and mesopic contrast sensitivity (MCS). METHODS: In a double-masked, placebo-controlled, cross-over study, 16 young normal volunteers were randomly assigned to one of four different regimens of single oral administrations of 12, 24 and 36 mg of anthocyanosides, and a placebo, with a 2 week washout period between doses. SRT, DAR and MCS were measured immediately before, and 4, 8 and 24 h after treatment. RESULTS: No significant effect was found on any of the three night vision tests during the 24 h following a single oral administration of 12, 24 or 36 mg anthocyanosides. The study had a power of 0.95 to detect a 0.1 log unit improvement in SRT and 0.5 log unit improvement in MCS. CONCLUSIONS: Single oral administration of 12-36 mg of anthocyanosides appears to lack significant effect on militarily relevant night vision tests.

Adult↗
PubMed1999

The effect of anthocyanosides in a multiple oral dose on night vision.

PURPOSE: In view of research demonstrating the ability of anthocyanosides in a multiple oral dose to improve night vision in normal individuals, we assessed their effect on three night vision tests: full-field absolute scotopic retinal threshold (SRT), dark adaptation rate (DAR) and mesopic contrast sensitivity (MCS). METHODS: In a double-masked, placebo-controlled, cross-over study, 18 young normal volunteers were randomly assigned to one of three different regimens of multiple oral administrations of 12 and 24 mg anthocyanosides, and a placebo, given twice daily for 4 days. A 2 week washout period was allowed between each 4 day treatment period. SRT, DAR and MCS was tested 1 day before and at days 1, 2, 3 and 4 during the treatment period. RESULTS: No significant effect was found on any of the three above-mentioned night vision tests. The study had a power of 0.95 to detect a 0.1 log unit improvement in SRT and 0.5 log unit improvement in MCS. CONCLUSIONS: Multiple oral administrations of 12 and 24 mg anthocyanosides twice a day appear to lack significant effect on night vision tests.

Adult↗
PubMed2002

Vision and eating behavior.

OBJECTIVE: Eating behavior is influenced by internal and external factors. Vision is one part of the complex pattern of factors influencing the amount of food consumed during a meal. The aim of this study was to explore the impact of vision on the microstructure of eating behavior and the subjective motivation to eat. RESEARCH METHODS AND PROCEDURES: Nine blind subjects and nine matched seeing control subjects consumed a standardized meal registered by VIKTOR, an eating monitor, measuring the microstructure of the eating behavior. The eating behavior of the control subjects was registered twice, with and without blindfold. RESULTS: The eating behavior of the blind subjects did not differ from that of seeing control subjects. However, the eating behavior of seeing subjects eating with blindfold demonstrated a clear impact of vision on eating behavior. When blindfolded, subjects ate 22% less food (p < 0.05), had shorter meal durations (p < 0.05), and had less decelerated eating curves (p < 0.05). Despite a smaller amount of food consumed when blindfolded, the reported feeling of fullness was identical to that reported after the larger meal consumed without blindfold. DISCUSSION: The importance of vision in regulating our eating behavior is further stressed in this study. Eating with a blindfold decreased the intake of food, without making subjects feel less full. Eating blindfolded, therefore, may force subjects to rely more on internal signals. These results might be used as an aid in the development of new treatment strategies for obese subjects.

Adult↗
PubMed2006

Quality of life and visual rehabilitation: an observational study of low vision in three general practices in West Glamorgan.

AIM: To survey low vision in an urban population and assess impact on quality of life, rehabilitation and support. METHODS: In a cross-sectional population survey, 66 patients were identified from databases of three general practices and surveyed by investigator administered questionnaire. Main outcome measures were ocular diagnoses, (US) National Eye Institute Visual Function-Questionnaire (NEI-VFQ) scores assessing visual and nonvisual disability, eligibility for, awareness and receipt of rehabilitation and support. RESULTS: Of 24,420 individuals on the lists of the three study practices, we found 101 registered as blind or partially sighted (prevalence 0.41%). A total of 66 patients participated with ocular diseases of age-related macular degeneration 39 (59%), glaucoma 11 (17%), diabetic retinopathy two (3%), retinitis pigmentosa two (3%), and 12 (18%) 'others'. Better eye visual acuity was counting fingers or worse in 32 (48.5%). NEI-VFQ scores were poor-overall mean 41.5% (SD 23.5). In all, 80% had a social services home visit with one-third of these still in contact. In all, 66% had undergone a low vision aid assessment and 57.6% of these used their aid. The awareness and receipt of benefits arising from registration as visually impaired were lower than for other supportive measures available for reasons unrelated to vision. None had a guide dog. CONCLUSIONS: We found expected patterns of low vision but poorer levels of function and support that may reflect age and deprivation in a population failed by the current systems for identification, registration, and rehabilitation based on legislation overtaken by demographic change and social provision independent of visual status.

Activities of Daily Living↗
PubMed2003

Measurement of indirect costs for people with vision impairment.

From a societal perspective, chronic eye diseases can affect not only the person who has vision impairment but also the economics of that society. To obtain comprehensive medical and non-medical expenditures for people with impaired vision, direct and indirect costs should be collected. Indirect costs are usually not included in cost evaluation in health economics due to the difficulty of the data collection and analysis. Questionnaires and cost diaries have been developed in this study to estimate total resource use, expenses, and lost production from the participants or their caregivers due to the participants' vision loss. Pilot testing was conducted to verify the format, clarity of instructions, relevance of content and completeness of the questionnaires and diary. Modifications were then made to the format from feedback from the participants. Diaries using large print, audio and Braille facilitate data collection for people with impaired vision.

Cost of Illness↗
PubMed2001

The ChromaGen contact lens system: colour vision test results and subjective responses.

The ChromaGen lens system is designed to enhance colour perception in colour vision deficiency (CVD). To investigate its efficacy, 14 CVD subjects were prescribed ChromaGen contact lenses. Colour vision tests (Ishihara, Farnsworth Munsell D-15, Farnsworth Lantern) were administered at baseline, lens dispensing, and after a 2-week lens-wearing trial during which subjective responses were recorded daily using visual analogue scales. ChromaGen lenses significantly reduced ishihara error rates (p < 0.001; ANOVA), particularly for deutan subjects. There was also a significant reduction in errors (p < 0.005) on the D-15 test. Conversely, lens wear had no significant effect on Farnsworth Lantern test performance. Subjectively, subjects reported enhanced colour perception, but poor vision in dim light. Judgement of distance and motion were only slightly affected. We conclude that ChromaGen lenses may enhance subjective colour experience and assist in certain colour-related tasks, but are not indicated as an aid for CVD in occupations with colour vision-related restrictions.

Adolescent↗
PubMed2001

Low vision in the geriatric population: rehabilitation and management.

Older persons represent the fastest growing segment of individuals with visual impairments in industrialized countries. This population is expected to grow dramatically in the coming years. This article discusses the common age-related changes in vision and the most prevalent visual impairments associated with aging, and the resulting functional implications. It includes information for health care professionals about preparing an older person to benefit from low-vision rehabilitation services, environmental evaluations and modifications, and orientation to the environment. The importance of functional assessment and instruction in the use of visual skills and vision devices is stressed. The article also emphasizes the need for teamwork to provide a full scope of rehabilitation services to older adults with low vision, and the importance of support by family members and caregivers to maximize coping, adjustment, independence and quality of life.

Adaptation, Psychological↗
PubMed2002

Vision, attention, and self-reported driving behaviors in community-dwelling stroke survivors.

OBJECTIVE: To elucidate the relationships among vision, attention, driving status, and self-reported driving behaviors in community-dwelling stroke survivors. DESIGN: A cross-sectional design to compare stroke survivors to older adults without stroke on visual measures, attentional measures, and self-reported driving behaviors. SETTING: Rehabilitation center at a university hospital. PARTICIPANTS: Fifty stroke survivors and 105 older adults without neurologic or visual impairment. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Visual acuity, contrast sensitivity, peripheral vision, useful field of view (UFOV), Behavioral Inattention Test, and a driving habits questionnaire. RESULTS: Stroke survivors had impaired contrast sensitivity, peripheral vision, and UFOV compared with older adults in good visual and neurologic health. Driving stroke survivors typically had less attentional impairment than nondrivers. Stroke survivors who returned to driving reported difficulty in challenging driving conditions, drove less, and relied more on other people for transportation than older adults without stroke. CONCLUSIONS: These results suggest that vision and attention, both of which are important for driving, are often impaired in stroke survivors. The severity of these deficits could be an influence on driving status and driving behavior. Stroke survivors who return to driving strategically limit their driving exposure and rely on others for transportation, which suggests that they may deliberately self-regulate their driving behavior.

Activities of Daily Living↗
PubMed2002

[Satisfaction with low vision aids].

PURPOSE: To study satisfaction with the prescription of low vision aids (LVA) and to correlate LVA with eye disease and visual function one year after prescription. METHODS: A questionnaire was sent out to 576 patients who had received LVAs in 1998. We evaluated their subjective satisfaction with the LVA as well as with the whole examination in our low vision department and compared the kind of LVA with disease and visual acuity. In addition, we observed whether additional functional deterioration led to problems with the LVA. RESULTS: 301 questionnaires were returned (52 %). They reported on high satisfaction with the management and the LVA (> 90 %). 57 % used their optical LVAs more than 5 times daily mostly for reading and writing (74 % and 78 %, respectively). However, 20 patients were no longer able to read with their LVA due to decrease of function. When comparing the LVAs, most patients with age-related macular degeneration were supplied with magnifiers (30 %). Thirty percent of the patients supplied with CCTVs (43 %; visual acuity 0.02 to 0.3) used the CCTV daily. CONCLUSIONS: The majority of low vision patients is very satisfied with the prescription of LVAs and frequently uses these aids. The adequate LVA is a major factor improving the quality of life. However, due to the possibility of greater deterioration after the disease, follow-up examinations on a regular basis appears to be necessary. The early prescription of CCTVs often helps to preserve the reading ability and should therefore be kept in mind by the physician dealing with low vision patients.

Adolescent↗
PubMed1997

[Use of a new optoelectronic vision aid for highly visually handicapped patients].

UNLABELLED: A new low vision aid (LVA)-the Low Vision Enhancement System or LVES, which were as developed at the Johns Hopkins University in Baltimore, is now commercially available. This instrument allows a magnification up to 10 times with control of contrast and luminance while the field of view is very large: 60 x 40 degrees. We present first results concerning LVES in comparison to conventional LVAs. PATIENTS AND METHODS: 60 consecutive patients suffering from macular dystrophy, macular degeneration, optic atrophy, tapetoretinal degeneration, or diabetic retinopathy were included in this study. We compared visual acuity with glasses, with telescope and using LVES. Furthermore we compared contrast acuity by the use of the Pelli-Robson-charts as well as the subjective impression of the patients. RESULTS: Improvement of visual acuity with LVES compared to correction with glasses was 8 log steps on average and up to 3 steps as compared to the use of telescopes. More important is the improvement of contrast sensitivity (0-16 steps) and the reduced glare. Despite the subjective improvement of visual acuity and contrast sensitivity the majority of patients could not imagine to use LVES regularly. A significant improvement as compared to conventional low vision aids is possible for special applications such as office work, recognition of faces or images or for looking at a blackboard. CONCLUSION: In addition to traditional LVAs, the Low Vision Enhancement System opens up possibilities for a very small group of patients. Especially patients suffering from macular dystrophy or Lebers optic atrophy may benefit from this new system. The most important advantage of LVES is the improvement of contrast sensitivity and the significantly decreased glare sensitivity. Additionally the near working distance is changeable. The variable magnification allows an easier fitting to various tasks. Prior to the prescription of LVES a detailed and time consuming testing is necessary.

Activities of Daily Living↗
PubMed1980

[Investigation of mesopic vision and sensitivity to glare by means of the new "nyktometer" (author's transl)].

In addition to photopic visual acuity both mesopic vision and sensitivity to glare play an important role in road traffic safety. It is known since the comprehensive investigations by Harms and Aulhorn that mesopic vision and sensitivity to glare are subjected to interindividually different changes with increasing age. 350 persons divided into three age groups were tested with a recently developed "Nyktometer" in order to gain some information about the influence of age on mesopic vision and sensitivity to glare. The results clearly show that both mesopic vision and visual performance in the presence of glare are strongly reduced with increasing age.

Adult↗
PubMed2005

Night-vision brain area in migratory songbirds.

Twice each year, millions of night-migratory songbirds migrate thousands of kilometers. To find their way, they must process and integrate spatiotemporal information from a variety of cues including the Earth's magnetic field and the night-time starry sky. By using sensory-driven gene expression, we discovered that night-migratory songbirds possess a tight cluster of brain regions highly active only during night vision. This cluster, here named "cluster N," is located at the dorsal surface of the brain and is adjacent to a known visual pathway. In contrast, neuronal activation of cluster N was not increased in nonmigratory birds during the night, and it disappeared in migrants when both eyes were covered. We suggest that in night-migratory songbirds cluster N is involved in enhanced night vision, and that it could be integrating vision-mediated magnetic and/or star compass information for night-time navigation. Our findings thus represent an anatomical and functional demonstration of a specific night-vision brain area.

Animal Migration↗
PubMed2000

Detection of female carriers of congenital color-vision deficiencies by visual pigment gene analysis.

PURPOSE: Congenital color-vision deficiencies are frequent among males, 4.7-8.0%, suggesting that female carriers are present at a frequency of 9-15%. The purpose of this study was to determine whether carriers could be detected by analysis of the visual pigment genes. METHODS: DNA from 29 males with congenital color-vision deficiencies, from their mothers, and from 117 randomly-selected females was analyzed. The most upstream genes, the downstream genes, and the most downstream genes in the red/green pigment gene arrays were amplified separately by PCR. Exon 5 of each gene was analyzed by single-strand conformation polymorphisms (SSCP). RESULTS: Analysis of the visual pigment genes suggests that one of the 29 mothers examined is a female protan and two others are carriers of both protan and deutan defects. The remaining 26 mothers were confirmed to be carriers of congenital color-vision deficiencies. Unusual patterns were observed in 15 (13%) of the randomly-selected females; among them, 5 appeared to be protan carriers and at least 4 to be deutan carriers. CONCLUSIONS: Female carriers of congenital color-vision deficiencies can be detected by analysis of the visual pigment genes. Since the proportion of females showing unusual patterns was slightly higher than expected, some must be false-positives and require more detailed examination.

Color Perception↗