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PubMed1987

Residual vision in patients with retrogeniculate lesions of the visual pathways.

Twenty-five subjects have been studied who, as a result of damage to the striate cortex, were 'blind' in extensive areas (scotomata) of the visual fields. Of these 25 subjects, 5 exhibited residual vision in response to transient lights presented within the scotoma, which enabled them to locate the stimuli by hand-reaching or by eye movements; the latter have been measured by electro-oculography. The residual vision underlying their responses was characterized by low flicker-fusion and by sensitivity in detection of movement which increased as target speed was raised. Discrimination for the direction of target movement was poor, but spatial resolution in the discrimination of target displacement was essentially normal. The subjects were unable to recognize or discriminate the spatial structure of targets located within the 'blind' field, and the observed dissociation between spatial discrimination of displacement and pattern is examined in relation to the 'two systems' hypothesis of visual function. There is no obvious correlation between the extent of neuronal damage as revealed by CT scans and the existence of residual vision.

Adult↗
PubMed2006

Cross-modal interactions between olfaction and vision when grasping.

This study used kinematics to investigate the integration between vision and olfaction during grasping movements. Participants were requested to smell an odorant and then grasp an object presented in central vision. The results indicate that if the target was small (e.g., a strawberry), the time and amplitude of maximum hand aperture were later and greater, respectively, when the odor evoked a larger object (e.g., an orange) than when the odor evoked an object of a similar size as the target or no odor was presented. Conversely, the time and amplitude of maximum hand aperture were earlier and reduced, respectively, when the target was large (e.g., a peach) and the odor evoked a smaller sized object (e.g., an almond) than when the odor evoked an object of a similar size as the target or no odor was presented. Taken together, these results support the evidence of cross-modal links between olfaction and vision and extend this notion to goal-directed actions.

Adult↗
PubMed1996

The importance of friendship and family support in adaptation to chronic vision impairment.

The importance of friendship and family support in adaptation for 241 elders experiencing age-related vision loss was examined. Adaptation was operationalized with two global measures of psychological well-being (life satisfaction, depressive symptoms) and a domain-specific measure, adaptation to vision loss. Hierarchical regression analyses tested the effects of sociodemographic, vision, health, and functional disability variables in the first step, family support quality in the second step, and friendship support quality in the third step. Variables entered at each step contributed significant portions of explained variance in outcome variables. Thus, the importance of friendship support, independent of family support, in adaptation to chronic impairment was demonstrated. The effect of relationship type and gender on multiple support components was also assessed. Scores for family support were higher than those for friend support on almost all components. Close relationships were perceived as providing greater attachment in females and greater instrumental assistance and social integration in males.

Adaptation, Psychological↗
PubMed1994

Vision impairment and functional disability among nursing home residents.

The relationship was explored between vision impairment, defined by best corrected distance acuity, and functional dependency among nursing home residents. All data, including clinical information on visual acuity, were collected from nursing home records. Almost one-fourth of all residents were found to have at least a moderate vision impairment (20/70 or worse) even after best correction with refractive lenses. Findings from hierarchical regression analyses indicate that vision status is an independent significant predictor of activities of daily living (ADL) functional dependency even after age, gender, and comorbidity are accounted for. Implications for nursing home services and future research are discussed.

Activities of Daily Living↗
PubMed1997

The relationship between vision impairment and the assessment of disruptive behaviors among nursing home residents.

This study examines the relationship between vision impairment, defined as best corrected distance acuity, and disruptive behaviors among nursing home residents (N = 89). All data were collected from nursing home records. Vision impairment was significantly related on the bivariate level to the disruptive behavior index (r = .21; p < .05). Hierarchical regression analyses, with disruptive behaviors as the criterion and age and comorbid conditions as covariates, indicate that vision status is a significant independent contributor to disruptive behaviors among long-term care residents. Several interpretations for this observed relationship are discussed, as are implications for nursing home services and future research.

Aged↗
PubMed2002

The molecular basis of dichromatic color vision in males with multiple red and green visual pigment genes.

We investigated the genotypic variation in 50 red-green color vision deficient males (27 deuteranopes and 23 protanopes) of middle European ancestry who possess multiple genes in the X-linked photopigment gene array. We have previously shown that only the first two genes of the array are expressed and contribute to the color vision phenotype. Therefore, the hypothesis is that the first two genes possessed by multigene-dichromats encode pigments of identical or nearly identical spectral sensitivity: one gene normal (R or G) and the other a hybrid (G/R or R/G). The spectral sensitivities of the encoded pigments were inferred from published in vitro and in vivo data. The color vision phenotype was assessed by standard anomaloscopy. Most genotypes (92%) included hybrid genes whose sequence and position and whose encoded pigment correlated exactly with the phenotype. However, one and possibly two of the protanopes had gene arrays consistent with protanomaly rather than protanopia, since two spectrally different pigments may be encoded by their arrays. Two of the deuteranopes had only R- and G-photopigment genes, without any detectable G/R-hybrid genes or any as-of-yet identified point mutation or coding/promoter sequence deletions. Further, an unexpectedly high number of multigene-deuteranopes (11%) had the C203R mutation in their most upstream G-pigment gene, suggesting a founder effect of middle European origin for this mutation. About half of the protanopes possessed an upstream R/G-hybrid gene with different exon 2 coding sequences than their downstream G-pigment gene(s), which is inconsistent with published data implying that a single amino acid substitution in exon 2 can confer red-green color discrimination capacity on multigene-protans by altering the optical density of the cones.

Color Perception↗
PubMed1994

Proposed protocol for a multi-centre study to compare clinical and trade tests of colour vision in firefighters.

Fire-brigade recruits in the UK have their colour vision screened using the Ishihara test. This is unsatisfactory because it rejects subjects with minor deficiencies in colour vision and does not test for blue defects. The Home Office is currently reviewing its recommendations on visual standards. This paper summarizes defects in colour vision, discusses alternative clinical and trade tests for the fire-brigade, and proposes a multi-centre study to collect data on the performance of fire-brigade recruits in clinical and trade tests.

Clinical Protocols↗
PubMed1996

Colour vision requirements of firefighters.

To perform their job safely firefighters must be able to identify colours on industrial gas cylinders, portable fire extinguishers, road traffic signals and several pieces of firefighting equipment. Although good colour vision is necessary we believe that the existing colour vision standard, which bars entry to the fire service to applicants who fail more than two plates of the Ishihara test, is unnecessarily stringent. We have identified and quantified the colour coded information encountered by firefighters. Colours were plotted on the CIE chromaticity diagram (1931) and isochromatic zones, which document the colour confusions of colour deficient observers, superimposed. This novel technique established possible colour confusions in different types of colour deficiency. Analysis of the results showed that red/green dichromats (protanopes and deuteranopes), severe deuteranomalous trichromats who fail the Farnsworth D15 test, and protanomalous trichromats are unsuitable for firefighting work. However, people with slight deuteranomalous trichromatism who pass the D15 test, are not disadvantaged and can be employed safely as firefighters. A new colour vision standard and a new testing procedure is recommended.

Color↗
PubMed1999

Medical students and congenital colour vision deficiency: unnoticed problems and the case for screening.

The results are given of a questionnaire study to determine the range of difficulties that doctors notice in their work due to congenital colour vision deficiency (CCVD). The study is primarily qualitative. A questionnaire was sent to 40 self-selected doctors, 35 of whom were general practitioners (GPs). All were administered a number of colour vision tests to assess the type and severity of their deficiency. Many difficulties and some ways of overcoming them were reported. Those with a mild deficiency reported fewer difficulties and this relationship was significant. Twenty-three of the doctors also reported difficulties as medical students and their answers are given verbatim. The results are discussed in relation to other studies and data on colour vision. The reasons for and against screening medical students for this deficiency are considered and it is concluded that there is a strong case for screening.

Color Perception Tests↗
PubMed1997

The role of vision and spatial orientation in the maintenance of posture.

This article reviews and analyzes the role of vision and spatial orientation in maintaining posture and balance. The key issues that relate to the development of postural control across the life span are discussed. Use of vision as a critical source of information that specifies spatial orientation in the environment is considered. We argue that the visual system functions as part of the perception-action cycle as promoted in ecological psychology by James Gibson. We compare and contrast theory and evidence of both standard and ecological accounts of how the visual system perceives the information and the findings relative to the role of the retinal vision in processing and acting on information related to motion. Changes in the ambient optical array (optical flow) as a non-force field are compared with gravity-based perturbations relative to the possible influence of the non-force field to changes in the motor system. Finally, a summary of some of our own work is presented, with comments about implications for further research and possible applications to clinical practice.

Humans↗
PubMed1996

Resection of bilateral orbital and cranial base basal cell carcinoma with preservation of vision.

The surgical resection of skull base tumors often presents technically challenging problems and can result in major deformities. In planning the operation, each individual patient must be evaluated not only with respect to the extent of the disease, but also with respect to the functional losses, which may severely affect the patient's quality of life. The patient presented is an elderly woman with a malignant anterior skull base basal cell carcinoma and multiple recurrences. The tumor extended to the orbits bilaterally, resulting in blindness in the right eye. The objective was to resect the tumor from the skull base and the orbits, while preserving vision in the left eye. Utilizing intraoperative frozen sections, extensive tumor resection in the left orbit was accomplished without compromising vision. This was followed by the reconstruction of the eyelids and periorbital tissues. Exenteration of the right orbit, anterior craniectomy, and partial dural resection were also performed. Ten years later, the patient remains free of tumor recurrence and has good vision in her left eye.

Aged↗
PubMed2002

Acquired monocular vision: functional consequences from the patient's perspective.

PURPOSE: The study is conducted to determine the effect of acquired monocular vision (enucleation, phthisis) on the daily activities of patients. METHODS: Sixty-five patients in a case series completed a 30-question survey evaluating the functional consequences of monocular vision. RESULTS: Patients with sudden visual loss adapted more slowly than those with gradual loss (8.8 versus 3.6 months). Difficulties with depth perception and cosmesis were prevalent. Unexpected consequences included neck pain, strain with reading, employment change, depression, car accidents, and alcoholism. Ninety-one percent of patients had no formal training to help them adapt. CONCLUSIONS: More than previously appreciated, there are many obstacles that patients face in making the transition to monocular vision. Few patients receive any formal instruction to help them adapt, yet many indicate that it would be beneficial.

Activities of Daily Living↗
PubMed1983

Sociodemographic differences in access to vision care among adults in the United States, 1974-1975.

Access to refractive care is examined by comparing uncorrected and corrected (with eyeglasses or contact lenses) distance visual acuity across eight race-sex-economic status groups. Of those with less than 20/20 uncorrected distance visual acuity, the age-adjusted proportion using corrective lenses is examined across these sociodemographic groups to assess unmet need in vision care. Measurements of distance visual acuity were obtained for 2,828 adults aged 25-74 years from the national probability sample selected for the 1974-1975 National Health and Nutrition Examination Augmentation Survey. Questionnaire responses were collected on usual correction. Individuals were classified by race, sex, and economic status. Weighted least squares categoric data analysis showed that blacks, males, and nonpoor persons have a higher proportion with 20/20 uncorrected distance vision than whites, females, and poor persons. Individuals who are white, male, and nonpoor are more likely to have 20/20 corrected distance vision than their counterparts.

Adult↗
PubMed1978

Research needs in low vision.

Research needs are presented for several areas of low vision: (1) reading and learning, (2) new low-vision aids, (3) modifying the environment, (4) utilization of disciplines, (5) new technologies, and (6) integrating low-vision services.

Audiovisual Aids↗
PubMed1981

Problem orientation in vision therapy.

Quantification and retrieval of data in vision therapy is a difficult task for both the private practitioner and optometric educator. The problem-oriented record provides an organizational approach that readily identifies patient's problems, therapeutic objectives, and the results of administered therapy. A minimum data base and the resultant problem list for vision therapy has been designed by us. By combining these two through a system of coding, a ready computer data retrieval system was devised. This system provides a method to clearly define terms, objectives, and results. Utilization of this record system by optometric schools and practitioners should reduce much of the confusion existing in the specialty field of vision therapy.

Amblyopia↗
PubMed1985

Vergence adaptation maintains heterophoria in normal binocular vision.

This investigation sought to determine whether vergence adaptation serves to maintain orthophoria or heterophoria in normal binocular vision. While wearing prisms which neutralized their nearpoint (40 cm) heterophorias, 27 of 30 nonstrabismic subjects adapted from their prismatically created orthophoria toward their habitual heterophoria. Three subjects showed no adaptive response. A symptom questionnaire distributed to these subjects determined that the maintenance of heterophoria by vergence adaptation is: characteristic of normal and comfortable binocular vision, and neither an entirely necessary nor sufficient condition for normal and comfortable binocular vision.

Adaptation, Physiological↗
PubMed1986

Dichromatic confusion lines and color vision models.

An attempt has been made to explain how dichromatic confusion lines can be used in building a model for color vision. In the König color vision model the fundamental colors are located on the mixture diagram at the copunctal points for protanopes, deuteranopes, and tritanopes. In Fry's model the copunctal points fall on the alychne and cannot represent the fundamental colors. On a constant luminance diagram the confusion lines for the different dichromats are sets of parallel lines. This arrangement of the confusion lines can be explained in terms of a zone theory of color vision.

Color Perception↗
PubMed1988

Treatment of low vision in the progressive cone dystrophies.

Twenty-three patients suffering from the progressive cone dystrophies (PCD) were evaluated retrospectively, after they had undergone treatment for low vision. All patients were able to read 1 M or smaller print with magnification, despite poor central acuity. Eighteen (78%) patients achieved their primary rehabilitation goal, and 86% of the low vision devices prescribed were used at follow-up. Photosensitivity was reported by a large number of patients. Seven patients indicated that alleviating this problem was their primary rehabilitation goal. Eight (35%) found sun filters to be helpful. Our successful experience with patients with these disorders suggests that examination for, and trial of, low vision devices is warranted.

Adolescent↗