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Albinism is inherited as autosomal recessive, with one exception: Ocular albinism, which has an x-linked trait. Visual symptoms include photophobia, varying degrees of nystagmus, reduction in visual acuity from 20/30 to 20/400 and varying degrees of moderate to high amounts of corneal astigmatism. Albinism patients respond very well to low vision devices and glare filters.
1. Loneliness has been linked to both psychological and medical problems. The study of loneliness and social support should interest nurses because nursing interventions may assist in preventing or alleviating potential health problems. 2. Study results indicate that low-vision older clients who lived alone were no lonelier than those who lived with others. Clients who lived alone were as satisfied with their social networks as those who lived with others. The actual number of supporters in the social network had no effect on loneliness for either group. 3. Neither group was particularly lonely. The nurse cannot assume that the combination of low-vision and living alone results in loneliness. Because different categories of supporters were linked to different areas of need, nurses need to help clients determine their emotional needs and identify who in the clients' network can best meet these needs.
BACKGROUND: A 5-year-old Hispanic male with an ocular history of retinopathy of prematurity was seen for an evaluation of his functional abilities and a determination of the possible treatment options for rehabilitation. The greatest concern was to provide the boy with the tools necessary to ensure success in the educational system. METHODS: A low-vision evaluation was performed and baseline information was obtained, including distance visual acuities, near visual acuities, visual fields and refractive error. This data was then used to determine if, in a classroom setting, the child would encounter any difficulties that could benefit from assistive optical devices or modifications of environment. RESULTS: The child demonstrated a large angle of head turn in order to eccentrically view to obtain his best visual acuity. His refractive error had no effect on this visual acuity at distance. Visual acuities taken at near demonstrated a working distance of 4 cm with preference to using the right eye. A gross confrontation field suggested a relatively full field in the right eye, but a temporal field loss in the left eye. CONCLUSIONS: A monocular bifocal system was prescribed for use in the classroom and at home when studying. The bifocal segment was a round +24 diopter aspheric lens, 22 mm in diameter, which was reshaped into a flat-top and adhered to a carrier lens. The carrier lens was ordered with 10 prism diopters base left in each eye. This system addressed both the large eccentric viewing position and the magnification necessary to alleviate the accommodative system.
From the eye care professional's point of view, the three most common types of albinism are tyrosinase-negative oculocutaneous albinism, tyrosinase-positive oculocutaneous albinism and ocular albinism. Skin and uveal hypopigmentation is variable in this condition depending on the type of albinism. However, all types of albinism lack the necessary uveal pigmentation have subnormal visual acuity. Using low vision rehabilitation techniques such as modifying lighting and providing telescopic optical devices, these patients can experience dramatic improvements in functional visual acuity. This manuscript examines strategic approaches to visual rehabilitation as well as provides a clinical review of the condition.
A letter counting task was presented on a Macintosh computer screen using two different versions of 24 point Times Roman print. One version, called "grainy," had 12 matrix units per font height and the other, called "smooth," had 24. A mixed group of low vision subjects and a normally sighted group had speed and accuracy measured as they performed the test task from two different viewing distances. For both population groups, the remote test distances were arranged individually so that the letters subtended an angular size scarcely larger than threshold. The close distances were fairly representative of practical working distances. It was shown that, for both groups of subjects, smooth letters allowed faster performance for the closer working distances only. Smoothing the letters helped accuracy of performance at the far distances, and at the close distances, smoothing improved the accuracy for the low vision group but not for the normals. The implications are discussed.
A telescopic system for distance consisting of a negative contact lens (-10.0 - -20.0 D) as the eye piece and a positive spectacle lens (+8.0 - +16.0 D) as the objective, a modification of the Galilean telescope was examined. First the system was tried in 15 normal subjects, whose visual acuity was reduced to 20/200 or less by providing several occlusion membranes, and results were compared with customary full correction for distance. The best improvement of their vision by this system was achieved when the dioptric power of the spectacle was between +11.0 D and +13.75 D. This system was then applied to 78 eyes (61 patients) with visual acuity of 20/100 or less. Subjective improvement of vision was found in 55% of those patients' eyes. Eight patients out of 26 patients whose better eye acuity was 20/100 or less wanted to use this system and received prescription to result in the visual improvement, as evidenced by their continued use. This system can provide aid for low vision correction for distance.
OBJECTIVES: To test the validity and reliability of measures of visual ability and to evaluate the relation between measurements made at the task level and measurements made at the goal level of a hierarchical model for visual disability. DESIGN: Validation of a telephone-administered functional assessment instrument using Rasch analysis on self-assessment ratings. SETTING: Telephone interviews of respondents in their homes. PARTICIPANTS: Consecutive series of 600 outpatients with low vision. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Ordinal ratings of the difficulty in performing a subset of 337 tasks. Measures of the visual ability of each patient and the required visual ability to perform each task were made using the Andrich rating scale model. Measurement validity and reliability were tested statistically by comparing response patterns and distributions to measurement model expectations. RESULTS: Results were consistent with a single visual ability construct. Patients' visual ability estimated from task difficulty ratings agreed with estimates from goal difficulty ratings ( r =.74); the difficulty of individual goals was equal to the weighted average of the difficulties of subsidiary tasks ( r =.79). However, conclusions from the Rasch analysis were not confirmed by principal components analysis of item residuals, which indicated that visual ability had a 2-dimensional structure, with 1 factor related to mobility and the other related to reading. Factor analysis on person measures estimated from subsets of functionally grouped items confirmed the 2-dimensional structure of visual ability. CONCLUSIONS: Our study results confirm the hierarchical structure of the Activity Breakdown Structure model and show how the individualized Activity Inventory can produce measures of limitations in functional vision.
PURPOSE: The study has investigated the effect of lighting on the daily activities (ADL) of the visually impaired in their homes by comparison before and after light adjustments were made in the kitchen, hall and bathroom. It has also investigated the additional effects on the quality of life after providing task lighting in the living room. METHOD: A total of 56 people were consecutively recruited from those receiving lighting adaptation help by the Low Vision Clinic in Göteborg. Ten persons did not complete the study. After medical examinations, lighting standards and psychosocial factors were charted. After lighting improvements were carried out in the kitchen, hall and bathroom, the subjects were randomly divided into two groups, an intervention and a comparison group. The task lighting in the living room was also improved for those included in the intervention group. Follow-up interviews to determine ADL and quality of life were performed 6 months after lighting adaptation. RESULTS: A marked effect on quality of life of the lighting in the living room was found for the intervention group. The effect on ADL of the basic lighting adaptation in kitchen, hall and bathroom for both groups was significant for tasks carried out on the working surface in the kitchen. Other activities in the kitchen and in the bathroom tended to improve but changes were not significant. CONCLUSION: The results confirm that it is possible to increase quality of life by improving the lighting conditions.
PURPOSE: To examine the causes and outcome of subnormal vision starting in childhood in Uganda, to aid in planning for its avoidance and for rehabilitation. METHODS: All those seen having subnormal vision with onset from birth to 15 years (total 1135) (schools 1983-97; community 1988-97) were included in the study. Clinical examination was performed and a World Health Organisation (WHO) form completed, with analysis by its computer program. Main outcome measures were visual acuity, signs of eye pathology, outcome of treatment and refraction and low vision assessment. RESULTS: By WHO category 14.8% had visual impairment, 6.5% severe visual impairment, 63.2% were blind and 15.2% were too young to test. The acuities and causes were similar in school and community groups, excepting cortical visual impairment and multiple impairment, which are much commoner in the community. Cataract was the largest cause of visual impairment (30.7%) and surgical outcome was unsatisfactory. Visual loss following corneal ulceration was the second commonest cause of subnormal vision (22.0%). CONCLUSIONS: Cataract and corneal damage cause half of all subnormal vision, which is avoidable for both. Cataract surgery needs to be upgraded. To prevent corneal visual loss, primary health care should continue to be expanded, especially measles immunisation and nutrition care; rubella immunisation should be added. Special education needs to be greatly expanded. Public perceptions need changing if results are to be improved and help offered to more than the present minority.
Two wall test charts with Snellen letters on both sides have been designed for the purpose of testing vision accurately, especially for the patient with low vision. Visual designations of 20/160 (6/48) and 20/125 (6/37.5) are included on the chart. This makes each line 26% larger. Sloan letters are used and arranged so that each line is of equal difficulty.
Patient use of low-vision aids to improve postoperative vision was evaluated in 32 eyes after successful repair of retinal detachment that involved the macular area. Despite best-corrected postoperative visual acuity ranging from 5/155 to 10/38, both distance and near vision could be improved in all cases using telescopic and microscopic systems, respectively. Patient acceptance of the telescopic systems was 62%, and of the microscopic systems, 96%.
When we look at our spatial environment we have the feeling that the whole visual field is coloured, yet the density of cone photoreceptors decreases considerably as eccentricity increases. We investigated colour perception (coloured/noncoloured), colour naming and whether colour helps object recognition at eccentricities varying from 0 degrees to 80 degrees in healthy observers and patients with low vision. We found that colours can be perceived and even identified above chance at very large eccentricities (60 degrees). When asked to categorize coloured and grey level objects as edible/nonedible, both healthy observers and patients with low vision showed better performance for coloured edible objects at 50 degrees suggesting that colour is used for object recognition in conditions of degraded form perception.
Visually impaired people rank obstacle location and identification as two of the most important mobility problems faced. Traditional mobility aids (the long cane) provide information about where an object is located but only within their limited (one metre) range. Although objects are located when traditional aids are used, it is unlikely that they are identified. The Bristol Mobility Aid (BMA) is an electronic travel aid that presents scene images to remaining residual vision in a number of view formats. Previous work has suggested visually impaired observers have better static object recognition using this aid. We investigated the mobility performance of subjects with retinitis pigmentosa using the BMA by determining the percentage preferred walking speed (PPWS), and the number of errors made with three different BMA headset views on an indoor mobility course. We found low-vision subjects had significantly reduced PPWS in two of the three headset views and interestingly, sighted subjects had significantly reduced PPWS when using the BMA in all three views. The numbers of errors made were significantly higher across all vision groups when the BMA was worn. We found that the BMA does not currently increase mobility in the visually impaired. Results are discussed in terms of modifications that could be made to the aid and methodological limitations.
A closed circuit television (CCTV) magnifier was used to measure the reading rates of nine fluent low-vision subjects. Performance was found to be dependent on field width, character size, and the number of characters displayed in line. A field width of 70 degrees and a mean of 24 characters were commensurate with the fastest reading rate. The optimal character size that elicited the fastest reading was determined for each subject. In seven of the nine subjects, this differed from the character size selected by chance at their initial CCTV sessions, prior to these experiments. A clinical procedure is recommended, which avoids inappropriate choice, and guides the examiner in achieving directly the most efficient CCTV reading conditions for each individual patient.
INTRODUCTION: Glaucoma is one of the major causes of visual impairment, especially in the older population. The aim of this paper is to examine the demographics of patients with glaucoma-induced visual impairment. METHOD: Visual rehabilitation information was analysed for 590 visually impaired patients attending the multi-disciplinary low vision clinic at Kooyong in Melbourne. Data collected included age, subjective assessment of glare, mobility and visual needs, visual acuity (at distance and near), contrast sensitivity, visual field loss or disruption and magnifiers prescribed. An assessment was also made of the patients' psychological status and the members of the multi-disciplinary team involved in their rehabilitation was noted. RESULTS: Glaucoma was the primary cause of visual loss in 8.5 per cent of patients and was a secondary contributor to visual impairment in 5.9 per cent. The mean distance visual acuity was 6/38 and peak contrast sensitivity was 10 dB. Sixty-four per cent of glaucoma patients had magnifiers prescribed to help them achieve their visual needs, which were to read newspapers in the majority of cases. CONCLUSIONS: In the management of low vision patients, it is important to understand the eye disease causing the visual impairment and its effects. The glaucoma sufferer must be treated as a whole person. The psychological state and the need for services such as welfare and mobility training must be considered to enable him or her to enjoy an improved quality of life.
The authors evaluated a preferential looking technique (Teller acuity cards) and a set of gross behavioral indicators (visual function battery) for the ability to rank visually impaired children and infants on the basis of their visual function. Fourteen older children with a diagnosis of cicatricial retinopathy of prematurity who were capable of giving Snellen acuities and a group of 31 preverbal infants with decreased vision due to a variety of causes were tested. Teller acuity card and visual function battery findings were highly correlated with each other (and with Snellen acuities in the older group); however, the Teller acuity cards provided better discrimination in the moderately visually impaired range, whereas the visual function battery was better in the severely impaired range. It is concluded that, in children and infants, visual function over the entire spectrum of low vision can be characterized by using a combination of the Teller acuity cards and the visual function battery.
Presentation of the Lausanne school for blind and visually impaired children. 38 children were admitted in the school in 1996-1997. 16 have a visual acuity of less than 3/60. Ocular malformations of various origins are the main reason of the handicap, followed by visual lesions of central origin. Comparing the study with those of 1992 and 1993, it seems that the number of retrolental fibroplasia and cataracts (operated or not) is decreasing. The authors present the educational care of these children. At present, the goal is to maintain the children in their own family. Most of them are day pupils and the transportation organisation is therefore very important. In special cases, it is possible to leave the children in a non-specialized school, provided the children receive a good educational support by one of our specialized low-vision teachers.
Normally sighted younger and elder subjects as well as subjects with central visual field loss (CFL) from age-related maculopathy read rapid serial visual presentation (RSVP) text with words presented at a constant rate and at three different rates where word presentation duration varied according to word length. The elder subjects reading sentences foveally read fastest when word duration was constant. The younger group reading random words peripherally read faster at a variable word duration rate. The subjects with CFL read sentences an average of 33% faster when the presentation rate varied with word length. There was a trend for slow readers with CFL to benefit more than fast readers with CFL. We conclude that varying word duration based on word length in rapid serial visual presentation reading would improve reading rates for low-vision patients with CFL.