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PubMed2005

A cost-effectiveness analysis of a health education programme for elderly persons with age-related macular degeneration: a longitudinal study.

PURPOSE: To analyse the cost-effectiveness of the activity-based Health Education Programme 'Discovering New Ways' versus a standard Individual Programme. METHOD: Two-hundred and twenty-nine persons were randomized to either the Health Education Programme or an Individual Programme. The present study is based on 131 persons who participated in the 28-month follow-up. Costs for the low vision clinic were documented prospectively along with external costs. A cost-effectiveness analysis was done using cases with an improved level of perceived security in daily activities as the effectiveness measure. RESULTS: The Health Education Programme led to significantly more cases with an improved level of perceived security (45 vs. 10%, CI 95%: 21-49, p value < 0.001) and the total social cost per treatment was lower (28,004 vs. 36,341 SEK). Taken separately the low vision clinic costs were slightly higher due to a higher prescription of assistive devices, but external costs were lower for the Health Education Programme compared to the Individual Programme, though neither of these differences was statistically significant. CONCLUSION: The results suggest that replacing the standard Individual Programme with the Health Education Programme 'Discovering New Ways' is cost-effective as more persons experience increased security to a lesser total cost.

Aged↗
PubMed2001

[Bilateral progressive supra-fixing eyes with congenital misinsertion of inferior rectus muscles--a case report].

BACKGROUND: We report on a rare case with misinsertion of the inferior rectus muscles, that showed bilateral progressive supra-fixing eyes. CASE: A 68-year-old woman showed bilateral progressive supra-fixing eyes with low vision that was caused by microcorneas and retionochoroidal atrophy. Passive infraduction was restricted bilaterally, but the right inferior rectus muscle was innervated normally. Magnytic resonance imaging(MRI) demonstrated nasal misposition of bilateral inferior rectus muscles. The patient's eye position was improved after combined transposition of the inferior rectus muscles that were misinserted nasally to the inferior poles of the eyes and superior rectus muscle recession, without any complications. CONCLUSION: A dysfunction of bilateral depressor muscles and low vision may cause this condition. Accurate diagnosis with MRI and correction of the affected muscles to the normal anatomical position produces satisfying results in such cases.

Aged↗
PubMed2002

Prevalence of visual impairment in people aged 75 years and older in Britain: results from the MRC trial of assessment and management of older people in the community.

AIMS: To measure the prevalence of visual impairment in a large representative sample of people aged 75 years and over participating in the MRC trial of assessment and management of older people in the community. METHODS: 53 practices in the MRC general practice research framework. Data were obtained from 14 600 participants aged 75 years and older. Prevalence of visual impairment overall (binocular visual acuity <6/18) which was categorised separately into low vision (binocular visual acuity <6/18-3/60) or blindness (binocular visual acuity of <3/60). The prevalence of binocular acuity <6/12 was presented for comparison with other studies. Visual acuity was measured using Glasgow acuity charts; glasses, if worn, were not removed. RESULTS: Visual acuity was available for 14 600 people out of 21 241 invited (69%). Among people with visual acuity data, 12.4% overall (1803) were visually impaired (95% confidence intervals 10.8% to 13.9%); 1501 (10.3%) were categorised as having low vision (8.7% to 11.8%), and 302 (2.1%) were blind (1.8% to 2.4%). At ages 75-79, 6.2% of the cohort were visually impaired (5.1% to 7.3%) with 36.9% at age 90+ (32.5% to 41.3%). At ages 75-79, 0.6% (0.4% to 0.8%) of the study population were blind, with 6.9% (4.8% to 9.0%) at age 90+. In multivariate regression, controlling for age, women had significant excess risk of visual impairment (odds ratio 1.43, 95% confidence interval 1.29 to 1.58). Overall, 19.9% of study participants had a binocular acuity of less than 6/12 (17.8% to 22.0%). CONCLUSION: The results from this large study show that visual impairment is common in the older population and that this risk increases rapidly with advancing age, especially for women. A relatively conservative measure of visual impairment was used. If visual impairment had been defined as visual acuity of <6/12 (American definition of visual impairment), the age specific prevalence estimates would have increased by 60%.

Age Factors↗
PubMed2000

[Treatment of exudative age-related macular degeneration].

I PROPHYLACTIC TREATMENT: We followed 75 eyes contralateral to eyes with exudative age-related macular degeneration (AMD), using indocyanine green angiography (IA), for more than one year. Hyperfluorescent areas in the late phase of IA were seen in 19 eyes at the initial examination, and in 25 eyes during follow-up. Exudative AMD developed in 9 of the 25 eyes. Using timetable analysis, we estimated that 11% of these 27 eyes developed AMD within one year and 55% within three years. The hyperfluorescent areas seen on IA appeared to be latent choroidal neovascularization (CNV) under the retinal pigment epithelium. We propose that photocoagulation aimed at hyperfluorescent areas should be considered in such cases. We performed prophylactic laser photocoagulation in 21 eyes, which were then followed up for at least six months. These eyes all had 10 or more serous drusen within 1,500 microns of the fovea and did not show hyperfluorescence, suggesting latent CNV in the late phase of IA. The majority or a small fraction of the serous drusen disappeared in 48% and 18% of the 21 eyes, respectively. CNV appeared adjacent to the laser scar in one eye (5%). Judging from these results, it is important to establish a method of definitively abolishing drusen and preventing the development of CNV. II TREATMENT OF CNV: Of 229 eyes which showed occult CNV in fluorescein angiography (FA), 124 eyes (54%) showed classic CNV outside the fovea on IA. One hundred and two of the 124 eyes (45%) underwent laser photocoagulation. We evaluated indocyanine green guided laser photocoagulation of extrafoveal CNV in 139 eyes. The success rate was 81% at 3 months after laser photocoagulation. This was estimated using timetable analyses to have decreased to 78% at one year and 71% at three years. Eighty percent of successfully treated eyes showed maintained or improved visual acuity. These results did not differ significantly from those obtained with laser photocoagulation based on FA findings. When classic CNV is not detected on FA, IA is indicated and if classic CNV is detected outside the fovea, photocoagulation should be performed aggressively. We compared the histological findings of removed subfoveal CNV with the IA findings prior to removal. IA findings of CNV before removal were divided into four types. Types I and II showed numerous vascular lumina in von Willebrand factor staining. Prominent proliferation in types I and II was demonstrated with Ki-67. Vascular endothelial growth factor (VEGF) showed strong staining in types I, II and III. Therefore, CNV in eyes with types I, II and III, and especially type I, requires urgent treatment. We compared visual outcomes one year after treatment between 52 eyes that underwent removal and 56 eyes that underwent laser photocoagulation of subfoveal CNV. When CNV size was one disc diameter or less, mean visual acuity, the percentage of eyes with improved vision and with a visual acuity of 0.1 or more, was significantly greater in operated eyes than in coagulated eyes. Removal is therefore superior to photocoagulation in subfoveal CNV of one disc diameter or less in size. We evaluated preoperative factors influencing the best corrected visual acuity at least six months after removal of subfoveal CNV in 67 eyes. Factors influencing the best corrected visual acuity were IA findings, feeder vessel ingrowth sites and CNV sizes. Good indications for removal included types I, II and III IA findings, extra foveal location feeder vessel ingrowth sites, and small CNV. III LOW VISION CARE: We performed reading tests using the MN read J chart for 90 eyes with the scar stage of CNV. Reading speed profiles of the 90 eyes were classified into two groups: 48 eyes showing a plateau with a relatively constant reading rate at the maximum level; and 42 eyes showing steadily increasing reading rate without a plateau. Eyes without a plateau had worse visual acuity, worse reading acuity, and slower reading speed. We evaluated newspaper reading performance by comparing conventional versus new methods based on the critical print size of the MN read J chart. Magnification power based on the critical print size were similar to those finally chosen as the best aid by the patients. On the other hand, magnification power was lower when conventional methods were used. The critical print size of the MN Read J chart appears to be valuable for determining low vision aids which facilitate reading by AMD patients.

Aged↗
PubMed2001

Changes in fixation in the presence of prism monitored with a confocal scanning laser ophthalmoscope.

BACKGROUND: The main optical effect of an ophthalmic prism is to deviate uniformly the entire field of view seen through the prism, resulting in an equal eye movement, if fixation on the same object is to be maintained. Conversely, it has been suggested that, in the case of low vision due to central scotoma, the eye changes its eccentric viewing behaviour when a prism is introduced, that is, the eye remains stationary with a change of retinal image location. METHOD: A new method is described in which retinal image position was recorded with a confocal scanning laser ophthalmoscope in four experimental conditions. RESULTS: Results showed that the normally-sighted eye rotates rapidly to compensate for the introduction of a prism. CONCLUSION: Future studies are required involving subjects with central scotoma but it is likely that many subjects with low vision will also refixate behind a prism and that the prescribing and wearing of bilateral prism in cases of central vision loss will have limited effectiveness in the demonstration or training of eccentric viewing.

Journal Article↗
PubMed2004

The prevalence and causes of visual impairment in Tehran: the Tehran Eye Study.

AIMS: To determine the prevalence and causes of visual impairment in Tehran, Iran, through a population based study. METHODS: In a population based, cross sectional study, 6497 Tehran citizens were sampled from 160 clusters using a stratified, random, cluster sampling strategy. The eligible people were enumerated through a door to door household survey in the selected clusters and were invited. All participants were transferred to a clinic for an extensive eye examination and interview. Visual impairment was determined using presenting and best corrected visual acuity (low vision: visual acuity of less than 6/18 to 3/60 in the better eye; blindness: visual acuity of less than 3/60 in the better eye). RESULTS: Of those sampled, 4565 (70.3%) people participated in the study. The age and sex standardised prevalences of visual impairment on the basis of best corrected and presenting visual acuity were 1.39% (95% confidence interval (CI), 1.07 to 1.71) and 2.52% (95% CI, 2.07 to 2.97), respectively. 15 people (0.28%; 95% CI, 0.14 to 0.42) were blind with corrected vision while 22 (0.39%; 95% CI, 0.23 to 0.56) were blind with presenting vision. Using the corrected and presenting vision, the prevalence of low visual impairment was 1.11% (95% CI, 0.84 to 1.39) and 2.13% (95% CI, 1.71 to 2.55), respectively. The causes of visual impairment according to the best corrected vision were cataract (36.0%), macular degeneration (20.0%), and amblyopia (10.7%). However, according to the presenting vision, uncorrected refractive errors were the most frequent primary cause (33.6%) and cataract (25.4%), macular degeneration (12.7%), and amblyopia (8.2%) were the other main causes of visual impairment in the study sample. The prevalence of visual impairment was associated with advancing age and lower education. CONCLUSION: The results indicate that the burden of visual impairment is important and, although easily preventable, uncorrected refractive errors and cataract have a major role as causes of visual impairment in this population. Results also highlight the need for visual impairment prevention programmes, with emphasis on treatment of refractive errors and cataract.

Adolescent↗
PubMed2006

Revision of visual impairment definitions in the International Statistical Classification of Diseases.

BACKGROUND: The existing definitions of visual impairment in the International Statistical Classification of Diseases are based on recommendations made over 30 years ago. New data and knowledge related to visual impairment that have accumulated over this period suggest that these definitions need to be revised. DISCUSSION: Three major issues need to be addressed in the revision of these definitions. First, the existing definitions are based on best-corrected visual acuity, which exclude uncorrected refractive error as a cause of visual impairment, leading to substantial underestimation of the total visual impairment burden by about 38%. Second, the cut-off level of visual impairment to define blindness in the International Statistical Classification of Diseases is visual acuity less than 3/60 in the better eye, but with increasing human development the visual acuity requirements are also increasing, suggesting that a level less than 6/60 be used to define blindness. Third, the International Statistical Classification of Diseases uses the term 'low vision' for visual impairment level less than blindness, which causes confusion with the common use of this term for uncorrectable vision requiring aids or rehabilitation, suggesting that alternative terms such as moderate and mild visual impairment would be more appropriate for visual impairment less severe than blindness. We propose a revision of the definitions of visual impairment in the International Statistical Classification of Diseases that addresses these three issues. According to these revised definitions, the number of blind persons in the world defined as presenting visual acuity less than 6/60 in the better eye would be about 57 million as compared with the World Health Organization estimate of 37 million using the existing International Statistical Classification of Diseases definition of best-corrected visual acuity less than 3/60 in the better eye, and the number of persons in the world with moderate visual impairment defined as presenting visual acuity less than 6/18 to 6/60 in the better eye would be about 202 million as compared with the World Health Organization estimate of 124 million persons with low vision defined as best-corrected visual acuity less than 6/18 to 3/60 in the better eye. CONCLUSION: Our suggested revision of the visual impairment definitions in the International Statistical Classification of Diseases takes into account advances in the understanding of visual impairment. This revised classification seems more appropriate for estimating and tracking visual impairment in the countries and regions of the world than the existing classification in the International Statistical Classification of Diseases.

Biometry↗
PubMedDate not supplied

Evaluation of fixation one year after perifoveal laser treatment of subfoveal choroidal neovascularization.

The natural prognosis of subfoveal neovascularization is severe visual acuity loss. Perifoveal laser photocoagulation is meant to spare a small portion of the central retina so as to possibly preserve foveal fixation. The aim of this retrospective study was to detect the persistence of central fixation and to evaluate the visual function of patients who had undergone perifoveal laser photocoagulation one year before, due to the presence of age-related macular degeneration with subfoveal neovascularization. The visual function was assessed by means of visual acuity (VA) measurement, central perimetry, scanning laser ophthalmoscope (SLO) scotometry and capability of using low-vision aids with success. Twelve eyes of 12 patients, 5 males and 7 females, with mean age 72.6 +/- 9.62 years, were included in the Study Group. Mean VA was 0.22 +/- 0.089 before laser treatment, 0.17 +/- 0.054 one week after laser treatment (p = 0.0152) and 0.13 +/- 0.063 one year after laser treatment (p = 0.045), with a statistically significant reduction of VA overtime (initial-final p = 0.0015). Mean lesion size was 2.12 +/- 0.528 disc diameters on the last follow-up fluorescein angiogram. One year after laser treatment, perimetry showed the persistence of central fixation in 2 eyes, while 10 eyes seemed to have lost it. SLO scotometry revealed central dot stimulus perception in 6 eyes and no central residual in 6 eyes. The SLO fixation plot showed persistence of central fixation also in 1 eye in which static perimetry had not detected it. The preferential retinal locus was located on the upper or upper-right margin of the lesion in 8 of the 9 eyes with paracentral fixation. All patients achieved a useful reading VA using low-vision aids, with 7.16 +/- 6.1 mean magnification power. The eyes with central visual residual on SLO scotometry had a final VA slightly higher than those without central residuals (VA 0.158 +/- 0.03 and 0.098 +/- 0.07, respectively), though the difference was not statistically significant (p = 0.0977).

Aged↗
PubMed1993

Visual requirements for reading.

We have applied research on the visual psychophysics of reading to low vision assessment. Research on different aspects of the reading process found that reading rate rather than reading comprehension is more sensitive to variations in a subject's visual functioning or the stimulus properties of print. The research identified four different visual factors that significantly affect reading rate: (1) acuity reserve [print size relative to acuity threshold], (2) contrast reserve [print contrast relative to contrast threshold], (3) field of view [number of letters visible], and (4) in cases of maculopathy, central scotoma size. Our research indicates that fluent reading rates can be attained with a restricted field of view, as little as four characters. However, attainment of fluent reading levels requires that print size and contrast should be several times threshold and the diameter of a central scotoma should be less than 22 degrees. Although important clinical studies are lacking, we derived specific visual requirements for different reading rates from published experimental research to provide a starting point and to illustrate how visual requirements could be derived, even with poor correlations. Research has made significant progress toward the development of a comprehensive low vision assessment that will allow the practitioner to identify visual impediments to reading, other than reduced visual acuity. Having more fully characterized a visual impairment, the practitioner may tailor devices or interventions to the individual's needs and capabilities.

Aged↗
PubMed2004

The prevalence of depressive symptoms among elderly Chinese private nursing home residents in Hong Kong.

BACKGROUND: Privately-owned Nursing homes (PNH) in Hong Kong present a unique setting of institutional care where elderly with the whole spectrum of health status live together. OBJECTIVES: This cross-sectional descriptive study aimed to determine the prevalence of significant depressive symptoms in a group of Cantonese-speaking Chinese private nursing home elderly living in Hong Kong, and to identify associated psychosocial and health factors. METHODOLOGICAL RESULTS: Two hundred and forty five residents fulfilled the inclusion criteria. Using the Chinese version of the Geriatric Depression Scale--Short Form (GDS-SF), we detected significant depressive symptoms in 29% of subjects. Univariate analysis revealed some associated socio-economic risk factors including current non-Comprehensive Social Security Assistance (CSSA) recipients, education levels and low abilities for social activities. Low vision, swallowing difficulties and low levels of basic activities of daily living (BADL) as reflected by the total Modified Barthel Index of less than 61 were important health predictors. Depression was also associated with features of self-perception of financial inadequacy, life dissatisfaction, poor self-perceived health, poor attitudes towards living arrangement and suicidal thoughts. Stepwise logistic regression identified swallowing problems, current non-CSSA recipient and low BADL ability as independent risk factors. CONCLUSION: The high prevalence of depressive symptoms in the nursing home elderly requires the attention of Government authorities, health care and social service providers.

Aged↗
PubMed1998

Adaptive response organizer network for space-time patterns in low level vision.

In this paper we present a biologically-inspired generalized artificial model of retinal neural response organization that can serve as a useful framework for analysis of response dynamics in artificial neural networks, specially in the visual systems. Adaptive Response Organizer (ARO), is an ON-centre OFF-surround class of artificial neural network models for feature abstraction and object identification under varying background conditions. The proposed architecture utilizes the existing literature on retinal functionality to develop a self-organized scheme to form visually evoked activation maps in response to arbitrary sequences of analog (gray scale) visual input patterns. It is conceptually organized into three processing layers, where visual information flows vertically through the layers and reorganized laterally by interneuronal action. The temporal response configuration of visually responsive neurons acquire the antagonistic centre-surround characteristics to promote detection of weak contrasts and rapid changes to transient and steady state stimulus at early stages of vision, for optical scene interpretation.

Journal Article↗
PubMed1979

[Risk of damage to the organ of vision in low birth weight infants].

The authors presented their own material of years 1974-1977. During this period 8788 children were born, in it 737 (8,3%) with low birth weight (below 2500 g). Retrolental fibroplasia was diagnosed in 4 children, it was 0,5% of newborns with low birth weight, and 0,04% of the all live-borns. The retrolental fibroplasia was diagnosed in: 1) the child born in 27 week of pregnancy with 1000 g of body weight, 2) in two children born in 32-33 week of pregnancy with 1450 g and 1350 g of body weight, 3) in a child born in 31 week of pregnancy with 1600 g of body weight. The infants were nursed in incubators with about 30% of oxygen during 36 to 46 days. Contemporary hypoglycemia, hypoproteinemia, atelectasia of lungs with respiratory insufficiency were diagnosed. In the discussion the authors underlined the role of immaturity and hypoxia of the premature baby, which play the role in the secondary injury of vessel's walls of retina. The disturbancy of carbohydrate and protein metabolism were certainly secondary pathogenic agent sin retrolental fibroplasia. There exists the necessity of oxygen therapy of premature baby, but to take cre of the infant in the incubator does not mean the necessity of oxygen therapy . Even with controlled oxygen dosage in incubator the retrolental fibroplasia may occur as a result of relative hyperoxydation induced by the constriction of retina vessels. The authors underlined the necessity of repeated ophthalmologic examination of premature babies in about every 2 weeks, what makes very early diagnosis possible.

Child, Preschool↗
PubMed1994

[Results of occupational rehabilitation of patients with severe vision impairment].

The authors had interviewed 134 former students of the Thuringian low vision school, of Weimar, concerning the course and outcomes of their vocational training as well as their current occupational situation at the study time, i.e. May/June 1990. The findings show a picture of largely successful vocational rehabilitation within the then-existing societal conditions.

Adolescent↗
PubMed2004

Image enhancement in the JPEG domain for people with vision impairment.

An image enhancement algorithm for low-vision patients was developed for images compressed using the JPEG standard. The proposed algorithm enhances the images in the discrete cosine transform domain by weighting the quantization table in the decoder. Our specific implementation increases the contrast at all bands of frequencies by an equal factor. The enhancement algorithm has four advantages: 1) low computational cost; 2) suitability for real-time application; 3) ease of adjustment by end-users (for example, adjusting a single parameter); and 4) less severe block artifacts as compared with conventional (post compression) enhancements. Experiments with visually impaired patients show improved perceived image quality at moderate levels of enhancement but rejection of artifacts caused by higher levels of enhancement.

Algorithms↗
PubMed2004

An instrument capable of grading visual function: results from patients with retinitis pigmentosa.

There was no device to grade visual function in patients with retinitis pigmentosa (RP). We have therefore developed an instrument capable of measuring and quantifying the visual capabilities, and here present the results from patients with RP. In total, 118 eyes of 59 patients, 26 men and 33 women, with RP were studied. Seven eyes had hand movement (HM) and eight had light perception (LP) vision, and the others had better visual acuity. The Low Vision Evaluator (LoVE) consists of a pair of goggles with white, light-emitting diodes as the stimulus, a control box, an on-off button to signal the detection of the stimulus, and a printer for permanent records. There are 15 luminance levels of stimuli (combination of 5 intensities and 3 durations). The stimuli are delivered in a random sequence with an audio signal presented 0.3 seconds prior to the light stimulus. Each eye was tested separately, and each stimulus magnitude (intensity x duration) was presented 3 times for a total of 27 stimuli per eye. With 6 catch trials (audio signal without a light stimulus), a total of 60 trials were examined in a full examination. The conventional visual acuity and kinetic visual fields were determined. 59 patients had different visual acuities that ranged from no light perception (NLP) to 1.5 vision, and visual field sizes that ranged from 0.0001 to 3.96 steradians. The visual acuity and visual field size were significantly correlated with the LoVE score (r=0.58 and 0.64, respectively; p<0.01). These results indicate that the LoVE is capable of grading the visual function of RP patients with various visual acuities and visual fields. The testing procedures are simple for the patient and examiner, and this instrument can be used to assess the effectiveness of medical and surgical therapy.

Adult↗
PubMed1998

Use of bioptic amorphic lenses to expand the visual field in patients with peripheral loss.

PURPOSE: To test the effectiveness of a bioptic form of a peripheral vision-enhancement lens in patients with retinitis pigmentosa (RP), choroideremia, and Usher's syndrome Type II. METHODS: Fifteen patients with peripheral visual field loss were trained in the use of the amorphic lenses for driving and other everyday activities for a 3-month period. A cross-over study design was used, where one group of eight patients received training during the first 3 months of the 6-month study, and another group of seven patients received training during the second 3 months. All patients were administered a battery of clinical, psychophysical, functional, mobility, and driving assessment tests at the beginning of the study, at 3 months, and at 6 months. The assessment tests were coded according to the primary visual skill involved in the task. These visual skills included: recognition, peripheral detection, scanning, tracking, visual memory, and mobility. RESULTS: After training, the patients showed improvement in all visual skills categories on the assessment tests, with overall improvement of 37%. There was no significant difference in the levels of improvement between the two groups. Those with smaller visual field extents showed significantly greater improvement on peripheral detection and scanning tasks. Those patients trained during the first 3 months of the study maintained their skills when tested at the 6-month point. CONCLUSION: Patients with peripheral vision loss may benefit from a rehabilitation program which combines low vision training with amorphic lenses in a bioptic configuration.

Adult↗