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PubMed1993

Suboptimal vision after vitreous surgery in diabetics.

Between 1979-1985, 105 diabetic patients underwent vitreous surgery for diabetic eye disease in one or both eyes. By spring 1991, 40 patients (38%) had died, and 36 (55%) of the living 65 patients had good or moderate vision (visual acuity, VA > or = 0.3 in the better eye), 13 (20%) had low vision (VA 0.05-0.25), and 16 (25%) were blind (VA < 0.05). For 19 of the 65 patients (29%) impaired vision was the main factor that limited independent activities. Of the 29 patients with suboptimal vision, 2 were employed, and none needed institutional care. Nine (31%) participated in all household activities, and 14 (48%) were able to read. Near vision aids were used by 14 of the 19 patients (74%) with ambulatory vision (VA > or = CF), but only 2 of them (11%) had accepted telescopic aids. Eight patients (28%) had a guide dog. In spite of vitreoretinal surgery, almost half of diabetic patients may end up with suboptimal vision, emphasizing the need for active visual rehabilitation.

Activities of Daily Living↗
PubMed1987

A comparative study in the use of closed-circuit television reading machines and optical aids by patients with retinitis pigmentosa and maculopathy.

Patients with retinitis pigmentosa (RP) who have insufficient vision to benefit from optical low vision aids are frequently helped by the closed-circuit television (CCTV) reading machines. RP patients' use of the CCTV is compared with that of patients with maculopathy (i.e. a group with a central scotoma only, is compared to a group which also has additional peripheral field loss), and with that of a "normal" control group. The performance of people with RP is improved by using white print on a black background, while macular degeneration subjects have no significant preference. Speed limits appear to be a function of restrictions imposed by the machine. Both groups frequently read faster with "optical aids".

Adolescent↗
PubMed1991

Adjustable focus telescopes for near vision.

It is important for clinicians to know the equivalent viewing power and corresponding equivalent viewing distance of the adjustable-focus telescopes they prescribe for low vision patients. Formulas are presented here to calculate the equivalent viewing power and distance of these telescopes. The optical effects of adjusting a telescope for near vision are discussed and compared to using a lens cap fitted on the objective to permit focusing on a near target. Commonly prescribed adjustable-focus telescopes of four representative magnifications were evaluated. The results are presented in the form of a nomogram which can be used for determining the equivalent viewing distance of these telescopes based on the front vertex focal distance of the focused device. Other considerations including sources of error and field of view are also addressed.

Eyeglasses↗
PubMed1998

Image enhancement improves reading performance in age-related macular degeneration patients.

We wanted to determine whether the 2- to 4-fold increases in reading speed found for patients with age-related macular degeneration (ARMD) when reading filtered text, presented one word at a time in the middle of the display would also be found when filtered text was scrolled across the screen. Reading speeds for filtered text that compensates for an observer's reduced contrast sensitivity function (CSF) were compared with the reading speeds for unfiltered text, when continuous, non-repeating text was scrolled across the display. The reading speeds of the ARMD observers tested were 1.7-4.5-times faster when reading filtered text, than when reading unfiltered text that was scrolled across the screen. The largest increments, over a 4-fold increase, were obtained in those subjects with the lowest unfiltered reading rates and the greatest loss of central vision. This study illustrates the usefulness of individualized text filtering for image enhancement in digitally based viewing devices to provide low vision remediation.

Aged↗
PubMed1992

Patients' responses to retinitis pigmentosa.

Forty-eight patients with retinitis pigmentosa completed at home a questionnaire about everyday tasks, and recorded their distance visual acuities on reduced Snellen charts. Respondents were asked to assess their own abilities for seven tasks involving visual search and mobility on a 1 to 4 scale. This revealed the relative difficulty of each task for the whole group. Other questions were open-ended to allow respondents to express their individual visual problems and experiences. Several problems came to light that were not amenable to treatment with low vision aids, but should be considered as a guide to the clinician in counseling.

Activities of Daily Living↗
PubMed1990

Recent experiences in the management of visual impairment in albinism.

One hundred patients with albinism seen within two years in the Low Vision Clinic at Moorfields Eye Hospital are reviewed. They are predominantly young people within the definition of 'Partially-sighted' rather than blind. Clinical methods are described and the distribution of alternative types of appliance loaned surveyed. Emmetropia and low ametropia are rare in the group. Most patients are using telescopic lenses for distance vision, tending to select binocular devices. Over half are able to read print of newsprint size in a clinical situation without extra magnification, but often elect to use extra magnification for some tasks. The need for near vision aids increases with age.

Adolescent↗
PubMed1996

Assessment of cataract surgery in rural India. Visual acuity outcome.

A socio-epidemiological assessment of what happens to the visual outcome after camp-based intracapsular cataract extraction was conducted in 6 villages and periurban areas in North India. 120 patients (143 eyes) were included in the study. The mean age at cataract extraction was 64.39 (range 33-83 years). 44.7% of the operated eyes obtained a good vision ( > or = 6/18) while 39.9% had low vision (6/24-3/60). The duration since the cataract extraction was seen to influence visual outcome. 70% of the respondents were satisfied with the surgical outcome. 76% of those with unilateral aphakia and 8.3% of those with bilateral aphakia were regularly using spectacles. 58.3% were satisfied with the spectacles. Dissatisfaction was generally due to lack of visual improvement. The major benefits accruing to the patients were improved personal activity, increased mobility and recognition of family members. It is our opinion that camp-based intracapsular cataract extraction with aphakic correction is still an important alternative in rural India.

Activities of Daily Living↗
PubMed1998

[Visual information processing and the mechanism of vision. Clinical application].

Psychogenic disturbance of vision includes various abnormalities such as low vision, abnormal visual field, abnormal color sense and disturbance of binocular function, although there are no abnormalities either in the eyeball or optic nerve, and no organic changes in brain computed tomography (CT) or magnetic resonance imaging (MRI). To clarify these abnormalities, it is necessary first to study the mechanism of visual information processing. In this report, the mechanism of visual information processing such as visual acuity, visual field, vision and attention and binocular function was studied by standard electrophysiological methods as well as by new techniques including electroencephalography (EEG) topography, visual evoked response imaging system (VERIS), and magnetoencephalogram (MEG). The following four items and the possibilities for clinical application were studied and discussed. The subjects were normal adults and child volunteers, patients with disturbance of vision of psychogenic origin, and patients with abnormal visual fields caused by organic changes in the visual pathway. 1. Visual acuity (form vision). 1) Visually evoked potemtial (VEP), early receptor potential (ERP), and MEG examination were carried out for normal subjects and patients with psychogenic disturbance of vision. 2) The P 100 of pattern reversal VEP of the patients showed a significantly higher response. 3) In normal subjects, the P 300 was observed widely around the Pz in the ERPs during Landolt's ring stimulation. 4) In normal children, the P 300 was observed slightly temporal to the Pz. 5) In some patients maximum amplitude of P 300 was observed in the occipital or temporal region, but in other patients there was no P 300 response in any derivation. 6) MEG in patients with the conversion type of psychogenic disturbance of vision showed only 2 small dipolar patterns around 117 ms during flash stimulation. It was quite different from that of normal subjects. 2. Visual field. 1) Multifocal VEP using VERIS could detect experimental artificial hemianopia caused by conclusion of the half visual field in normal subjects. 2) Multifocal VEP could detect hemianopia or quadratanopia. 3) In multifocal VEP in normal subject, off-latency time was about 36 ms longer than on-latency time both in the center and at the periphery of the retina. The ratio of on/off response decreased from the center to the periphery. 4) In MEG using flash stimulation, hemianopia could be detected even in patients with fixation difficulties. 5) As the subjective visual field was not always in accord with the objective field, objective visual field evaluation is important. 3. Vision and attention. 1) To confirm the influence of attention on visual information processings in patients with disturbance of vision of psychogenic origin, a hypothetical 'island of attention' was postulated. 2) The 'spiral visual field' and the 'Inazuma-type visual field' could be explained by application of this hypothesis for patients with disturbance of vision. 3) Three kinds of waves in VEF, W 1, W 2, and W 3, were detected by MEG after the stimulation of line motion illusion. There was a tendency for the latency time on the attention side to be shorter than on the non-attention side in waves W 2 and W 3. 4) There was a tendency for the amplitude of the attention side to be higher than that of the non-attention side in wave W 3. 5) Attention may influence vision. 4. Binocular vision. 1) A stimulus target was devised which did not elicit N 75, P 100, or N 140 waves. When this target was used for stereoptic stimulation, a negative wave was elicited with a latency of 170 to 280 ms. 2) When the same stimulus target without parallax was used, this negative wave was elicited but the amplitude was small. 3) When evoked potentials were measured under the same conditions, an electric dipole was elicited from the occipital to the temporal region by the electric current source. (ABSTRACT TRUNCATED)

Adolescent↗
PubMed1990

Visual and neural function in Leber's optic neuropathy.

This report details the chronology of vision loss for an 18-year-old Caucasian male with Leber's optic neuropathy. Findings of an oculo-visual assessment with auxiliary in-office tests of visual neural function, results of neurophysiological testing, and rehabilitative therapy with low vision aids are presented. The clinical characteristics of this devastating disorder are reviewed.

Adolescent↗
PubMed2005

The development of the Indian vision function questionnaire: questionnaire content.

AIM: To elicit problem statements describing the consequences of vision impairment as a first step towards the development of a vision related quality of life instrument for use in India METHODS: 46 focus groups were conducted in three regions of India. Separate focus groups were held for men and women and according to disease categories: cataract (24), glaucoma (six), diabetic retinopathy or macular degeneration (10), and "mixed low vision" (six). Facilitators followed a topic guide and sessions were audio taped and transcribed. Problem statements were extracted and coded and summarised into major problem domain areas. RESULTS: Nearly 5000 problem statements, an average of 15 statements per participant, were consolidated into 18 broad domain areas. The most important problem areas accounting for over 50% of all statements were ambulation, household or occupational activities, vision symptoms, and people recognition. A further quarter of statements related to difficulties with eating and drinking, psychological concerns, self care, reading, and watching television. Problem statements were similar across the disease groups, although rankings varied. CONCLUSIONS: The functional and psychological impacts described by visually impaired participants in India are similar to those reported in other population settings although the context and impact of problems vary.

Activities of Daily Living↗
PubMed2000

Understanding nystagmus.

BACKGROUND: Nystagmus is one of the more-common, yet least-understood, neuro-ophthalmic findings in the clinical setting, affecting one in every 5,000 to 10,000 individuals. Several electrodiagnostic techniques are available for characterizing congenital nystagmus, as well as for differentiating it from pathological forms. Ruling out central nervous system involvement is critical. A variety of treatments--including contact lenses, optical aids, vision therapy, biofeedback, pharmaceuticals, surgery, and low-vision rehabilitation--are available to nystagmus patients to improve visual functioning. Eye care practitioners should be familiar with this condition, its differential diagnoses, and strategies for management. METHOD: A comprehensive guide for clinical management of nystagmus is presented. Concerns such as differentiating congenital nystagmus from acquired nystagmus and management techniques for both forms of nystagmus are described. Myths of congenital nystagmus are dispelled, while newer theories are reinforced by the presentation of current research. CONCLUSION: Although nystagmus is a complicated entity, the optometric practitioner can successfully manage cases by using principles of diagnosis and being aware of the unique problems associated with nystagmus.

Humans↗
PubMed1999

The decrease of visual acuity in cataract patients waiting for surgery.

PURPOSE: To investigate the rapidity of vision loss in eyes waiting for cataract surgery and to estimate what proportion of life expectancy the extended wait for surgery comprised. METHODS: The visual acuities at the time of referral and on the day before surgery were compared in 124 patients operated on for cataract in the Vaasa Central Hospital, Finland. The expected survival of the patients after surgery was calculated individually using the Finnish life statistics. RESULTS: During the waiting time of 13 months on the average, the visual acuity in the study eye decreased from 0.68 logMAR (0.2 in decimal values) to 0.96 logMAR (0.1). The average decrease in vision was 0.27 logMAR per year varying from none to 2.07 logMAR units. 30% of the eyes experienced worsening of vision by 60% or more while 48% had no or minimal worsening (<0.2 logMAR). The rapidity of change in visual acuity was somewhat less in older patients (75 years or older), but the difference was not statistically significant. The percentage of persons with visual acuity of 0.5 or better in the better eye decreased from 66% to 41% and those with low vision (<0.3 in the better eye) increased from 8% to 21%. The mean waiting time in relation to the expected survival for all patients was 13% varying from less than 5% in 10 patients to more than 25% in 8 patients. CONCLUSION: Progression of vision loss in eyes waiting for cataract surgery varies significantly. For many patients the extended delay caused remarkable disability for a considerable part of their remaining lifetime.

Aged↗
PubMed2005

Social and visual function in nystagmus.

AIM: To investigate the influence of nystagmus on visual and social function and determine if parents are able to assess visual and social function in children with nystagmus. METHOD: A postal questionnaire comprising 14 questions related to visual function (VF-14) and questions pertaining to social function were sent to all 1013 members of the Nystagmus Network-a UK based organisation for nystagmus sufferers and their families. Visual and social function scores were compared by regression analysis. RESULTS: 180 adult, 233 parent, and 124 child questionnaires were returned. Idiopathic nystagmus was the most common cause. In adults the mean VF-14 score indicated very low visual function, in the same range as patients assessed in low vision services. Children's visual function scored better than adults, between scores of patients with age related macular disease and corneal grafts. There was a strong correlation between perceived visual and social function for adults (p<0.001) and parental assessment of their children (p<0.001), but not between child self assessment of visual and social function. There was strong correlation between parental and child assessment of visual and social function (p<0.001, p<0.001) CONCLUSION: Questionnaires indicated that nystagmus is associated with very low visual function. There is a strong correlation between visual and social impairment. The authors have shown for the first time in an ophthalmic disease that parents are able to estimate the impact of nystagmus on their child both in terms of visual and social functioning, although they underestimate the impact of nystagmus on emotional aspects of wellbeing.

Adolescent↗
PubMed2006

Visual field expansion in patients with retinitis pigmentosa.

BACKGROUND: To determine the effectiveness of using spectacle-mounted prisms for field expansion in patients with retinitis pigmentosa (RP). METHODS: Vision-related activities of daily living (V-ADL) questionnaire scores and functional visual field score (FFS) measurements were conducted before and after a one-month trial of spectacle-mounted prisms in those patients with RP who had residual central visual fields of less than 10 degrees. RESULTS: 16 patients were recruited who met study inclusion criteria. Mean V-ADL and FFS at baseline were 67.6 (73%) and 22.9 (46%), respectively. After a 1-month trial using spectacle-mounted prisms, V-ADL and FFS demonstrated significant improvement to 73.4 (80%, p < 0.05) and 27.0 (54%, p < 0.001), respectively. INTERPRETATION: Spectacle-mounted prisms effectively create visual field expansion and noticeable spatial orientation benefits in patients with RP. This may provide an adjunctive tool in low vision rehabilitation and should be considered in all cases with RP with less than 10 degrees of visual field.

Adult↗
PubMed2000

Distance telescopes: a survey of user success.

The distance telescope has a historical reputation for causing difficulties in prescribing and adaptation. Hence, we considered that a retrospective survey of patients at Nottingham Low Vision Clinic might elucidate specific attributes that influence an individual patient's success in using a distance telescope. From 142 patients prescribed distance telescopes since the Clinic's inception, 133 apparently remained users and were mailed a preliminary three-question enquiry about usage of their distance telescopes. The 87 respondents were followed up with questionnaire 2, requesting explicit information about usage, namely frequency, degree of ease or difficulty, and purpose. Older patients required higher magnification (p < 0.025). Seventeen of 74 respondents to questionnaire 2 had various adaptational problems, which are discussed; 57 of 74 patients found their distance telescopes easy to use, and 49 of 57 were frequent users. Thus, ease and frequency are linked (p < 0.05). People tended to use their distance telescopes outdoors and indoors with similar frequency (p > or = 0.29). Adaptation was found to be unrelated to visual acuity, binocularity/monocularity, ocular pathology, or restricted mobility; magnification seemed to be influential, although not significantly. Aging did not significantly impede adaptation. We infer that the universal criterion for selecting treatable patients seems to be personality type. We conclude that adaptation to a device is dependent upon active recognition of its benefits, paralleled with a tolerance of its constraints, which combine to make usage easy and regular on at least one common task.

Adaptation, Physiological↗
PubMed2006

Reliability and consistency of dark-adapted psychophysical measures in advanced eye disease.

PURPOSE: To establish reliable vision measures allowing functional monitoring in patients with severe vision loss. METHODS: Legally blind and normally sighted subjects were enrolled in a repeated-measures study to determine the reproducibility of psychophysical vision measures under scotopic conditions. The tests included dark adaptometry, dark-adapted, full-field flash testing, and dark-adapted macular thresholds, obtained by using a perimeter with 500- and 650-nm targets. Two to five test repetitions were performed on the better eye of each subject at monthly intervals. Subject groups included retinitis pigmentosa (RP; n = 33), macular disease (MD; n = 14), optic nerve disease (ON; n = 4), diabetic retinopathy (DR; n = 5), and other retinal diseases (OR; n = 9), and normally sighted control (CTL; n = 12). RESULTS: Dark adaptometry timing yielded mean coefficients of variation for subjects across all groups that averaged approximately 20% throughout the test. For dark-adapted perimetry, the coefficients of repeatability (CR(.95)) were <7 dB (CTL), <8 dB (OR), <6 dB (ON and RP), and <15 dB (MD). Full-field flash test CR(.95) by group varied from 5 to 15 dB, and most low-vision groups performed more reliably than CTL subjects. CONCLUSIONS: Dark-adapted psychophysical tests can provide reproducible vision measures in subjects with severe visual impairments, and these tests would be useful in monitoring outcomes in future clinical trials to reverse, halt, or slow vision loss. The most valuable measure of remaining vision was the dark-adapted, full-field flash test, as it produced repeatable results at all levels of vision loss and for all disease states included in this study.

Adult↗
PubMed2006

Evaluation of cross-sectional and longitudinal construct validity of two vision-related quality of life questionnaires: the LVQOL and VCM1.

The Low Vision Quality of Life (LVQOL) questionnaire and the Vision-related Quality of Life Core Measure (VCM1) are two of the many vision-related quality of life (QOL) questionnaires that have been developed in recent years. Although psychometric properties of the LVQOL and VCM1 compare well with other vision-related QOL questionnaires, construct and longitudinal validity have not been assessed (adequately). The purpose of this study was to examine the cross-sectional and longitudinal construct validity of these questionnaires by testing specific pre-specified hypotheses about the relations of these questionnaires with other measures. The percentage of hypotheses regarding the cross-sectional construct validity that were refuted for the LVQOL was 22% for the basic aspects of vision subscale, 50% for the mobility subscale, 39% for the adjustment subscale and 17% for the reading and fine work subscale. For the VCM1 this percentage was 57%. For the longitudinal construct validity the percentage of hypotheses that were refuted ranged from 33 to 75% for the LVQOL subscales and was 50% for the VCM1. In conclusion, cross-sectional construct validity was satisfactory for the LVQOL subscales, but seemed poor for the VCM1. In addition, the longitudinal validity of these scales was poor to moderate.

Aged↗
PubMed1985

Aiding the vision in albinism--optical and non-optical means considered.

Not 'Low Vision Aids' alone, but the full range of methods of helping sight in these visually handicapped persons--a much wider range than is generally realised--and which includes many non-optical manoeuvres and various 'gadgets' available to all forms of defective vision, as well as the newer electronic aids is described. The difficulty for the ophthalmologist in knowing how best to help patients with albinism should be resolved by 'customer research'; this paper attempts to do so by analysis of a questionnaire to members of the Albino Fellowship.

Adolescent↗