Non-correctable Visual Impairment Research Articles

Children's visual impairment and visual care related to socioeconomic status in Catalonia (Spain).

The objective of this study is to assess the prevalence of visual impairment and visual care practices and its association with socioeconomic conditions in the infant population in Catalonia. The Catalan Institute of Statistics provided a random sample of 0 to 14-year-old non-institutionalized children whose parents were interviewed in a continuous health survey from 2011 to 2015 in Catalonia. A multistage stratified and random sampling procedure considering age, sex, county and town was followed. All results have been weighted according to the sample design and are presented as the proportion of the condition with its 95% confidence limits. Chi-square tests were performed to evaluate the association between categorical variables. To study the association of visual care with independent variables, a multiple logistic regression model was used. In 0 to 14-year-old children, a 12.9% (95% confidence interval [CI] [11.8-13.9]) prevalence of correctable visual impairment was observed. The prevalence of non-correctable visual impairment was 0.9% (95% CI [0.6-1.2]). Non-correctable visual impairment was more prevalent in families with lower education levels, manual professions or unemployed. Of children without visual impairment, 13,5% (95% CI:12.3-14.6) visited a visual care professional in the last 12 months while this proportion was 67.4% (95% CI [63.3-71.5]) among those with correctable visual impairment. When parents have a university degree or non-manual professions, a higher level of visual care was observed. In children with correctable visual impairment, visual reviews were more frequent when parents are employed in a non-manual profession. For the first time, indicators related to visual impairment in children in Catalonia have been recorded. There is an association between lower socioeconomic status and having non-correctable visual impairment, and conversely, having correctable visual impairment was significantly associated with employed parents. More visual care is associated with higher socioeconomic status.

Visual impairment and ten-year mortality: the Liwan Eye Study.

To explore associations between visual impairment (VI) and mortality in an adult population in urban China. The Liwan Eye Study was a population-based prevalence survey conducted in Guangzhou, Southern China. The baseline examination was carried out in 2003. All baseline participants were invited for the 10-year follow-up visit. VI was defined as the visual acuity of 20/40 or worse in the better-seeing eye with habitual correction if worn. Correctable VI was defined as the VI correctable to 20/40 or better by subjective refraction, and non-correctable VI was defined as the VI correctable to worse than 20/40. Mortality rates were compared using the log-rank test and Cox proportional hazards regression models. Of the 1399 participants (mean age: 65.3 ± 9.93 years; 56.4% female) with available baseline visual acuity measurement, 320 participants (22.9%) had VI. After 10 years, 314 (22.4%) participants died. Visually impaired participants had a significantly increased 10-year mortality compared with those without VI (40.0% vs. 17.2%, P < 0.05). After adjusting for age, gender, income, educational attainment, BMI, history of diabetes and hypertension, both VI (HR, 1.55; 95% CI, 1.14-2.11) and non-correctable VI (HR, 2.72; 95% CI, 1.86-3.98) were significantly associated with poorer survival, while correctable VI (HR, 0.99; 95% CI, 0.66-1.49) was not an independent risk factor for 10-year mortality. Our findings that VI, particularly non-correctable VI, predicting poorer survival may imply the underlying mechanism behind VI-mortality association and reinforce the importance of preventing and treating disabling ocular diseases to prevent premature mortality in the elderly.

The prevalence and causes of visual impairment and blindness among older adults in the city of Lodz, Poland.

To investigate the prevalence and causes of visual impairment and blindness in a sample of Polish older adults.The study was designed in a cross-sectional and observational manner. Data concerning the vision status were assessed in 2214 eyes from 1107 subjects of European Caucasian origin; most of whom live in the city of Lodz, in central Poland. Visual impairment was defined as distance visual acuity <20/40 in the worse-seeing eye. Low vision was defined as best-corrected visual acuity (BCVA) <20/40 but >20/200 in better-seeing eye, and blindness was defined as BCVA ≤20/200 in both eyes (United States criteria).Visual impairment was found in 27.5% subjects in the worse-seeing eye. Multiple regression analysis showed that increasing age (OR 0.98, 95% CI 0.97–0.99) and female gender (OR 1.47, 95% CI 1.11–1.93) were independent risk factors. No association was found between visual impairment and socioeconomic status of subjects. Noncorrectable visual impairment was found in 7.0% of subjects, including 5.2% of subjects with unilateral and 1.8% of subjects with bilateral visual impairment. Low vision and blindness accounted for 1.3% and 0.5%, respectively, and were only associated with older age (OR 1.05, 95% CI 1.02–1.10). Retinal diseases represented the major cause of noncorrectable visual impairment and accounted for more than half of causes of blindness.Provision of appropriate refractive correction improves visual acuity in 75% subjects presenting with visual impairment. Retinal diseases are a major cause of noncorrectable visual impairment and blindness in this older population.

Motion perception within the blind hemifield

BackgroundHomonymous visual field deficit is a common clinical problem, most frequently caused by stroke or traumatic brain injury. After 3 months, the visual field loss is generally considered to be permanent. In certain cases, however, information within the blind hemifield can influence behaviour despite the individual often having no conscious awareness of the stimulus. The mechanism and extent of this function remains poorly understood, especially in cases of adult-onset injury. We aimed to investigate the ability of patients with primary visual cortex damage sustained in adulthood to detect and discriminate direction of low-luminance moving targets within the blind visual field. Our hypothesis was that individuals will retain some ability beyond chance, optimally for speeds between 8°/s and 30°/s. MethodsParticipants were recruited from ophthalmological or stroke services in three UK centres. Testing was done at the John Radcliffe Hospital, Oxford. Of 14 participants recruited, two were excluded after structural imaging showed almost complete damage to the occipital lobe, extending to parietal and temporal lobes including subcortical nuclei. Cases with additional non-correctable visual impairment, or previous neurological disease, were also excluded. All patients had sustained unilateral damage to the primary visual cortex (V1), causing homonymous visual field loss recorded by Humphrey perimetry. Pathological changes had been caused by posterior circulation stroke in 11 patients, or by benign tumour resection in three patients, at least 6 months previously. Psychophysical testing was conducted with a 60Hz monitor at a distance of 68 cm. Visual stimuli consisted of moving black dots (8 dots per deg2) in an aperture of 5° or 8° diameter. Stimulus location was restricted to the scotoma, on a grey background. Each stimulus appeared for 500 ms with jittered onset while the participant fixated on a central black cross. In experiment 1, participants indicated whether a stimulus appeared in the first or second time-interval. If they saw nothing, they were instructed to guess. In experiment 2, participants reported horizontal or vertical direction of motion. In both experiments, stimulus speed was altered parametrically: 4°/s, 8°/s, 20°/s, 32°/s, with 20 trials per condition. Fixation was recorded with an eye tracker, and any trials containing eye movements were removed from analysis. All patients underwent high-resolution structural MRI on the day of testing. Primary outcome was whether patients could demonstrate significant detection or discrimination of visual stimuli above chance. Secondary analysis considered how accuracy altered as a function of stimulus speed. Statistical testing was modelled with a binomial distribution. Written and verbal consent was given by all participants. Ethics approval was provided by the Oxford Research Ethics Committee (ref B 08/H0605/156). FindingsEight patients showed significant detection above chance (patient [P] 1 94%, p<0·01; P2 55%, p=0·04; P3 57%, p=0·03; P4 58·8%, p=0·02; P5 55·8%, p=0·04; P6 67·3%, p=0·01; P7 69·9%, p=0·001; P8 100%, p<0·001), and three patients correctly discriminated direction of motion (P4 75%, p=0001; P6 60%, p=0·018; P7 58·7%, p=0·026). Group analysis revealed an inverted-U pattern of accuracy as a function of speed across both experiments. Performance was best at 20°/s (mean detection 60·3% [SE 3·1], p<0·001, with patients 1 and 8 excluded from analysis because of performance at ceiling; mean discrimination 56·0% [SE 2·6], p=0·01), and also significantly above chance at 4°/s and 8°/s, but not 32°/s. InterpretationThis study is one of the few to assess visual performance in patients with homonymous visual field deficit due to primary visual cortex damage in adulthood. We have shown that even low-contrast complex motion can elicit blindsight in most patients, with optimum detection and discrimination at speeds of 20°/s. In some cases, particularly for direction discrimination, differences in performance can be subtle. Such trends become more apparent at a group level, or perhaps if patients were to undertake a greater number of trials. Performance as a function of speed echoes research into motion processing in area MT+/V5, where an optimum response is seen for intermediate speeds. It provides further evidence for a direct, perhaps subcortical route to this region when V1 is damaged, which may be present in most patients with these areas intact. That slow motion (postulated to depend upon V1 processing) was discriminated above chance, though small, warrants further investigation. FundingRoyal Society, Wellcome Trust, NIHR Oxford Biomedical Research Centre.

Direct and Indirect Effects of Visual Impairment on Mortality Risk in Older Persons

To investigate pathways from visual impairment to increased all-cause mortality in older persons. The Blue Mountains Eye Study examined 3654 persons 49 years and older (82.4% response) during 1992-1994 and after 5 and 10 years. Australian National Death Index data confirmed deaths until 2005. Visual impairment was defined as presenting, correctable, and noncorrectable, using better-eye visual acuity. Associations between visual impairment and mortality risk were estimated using Cox regression and structural equation modeling. After 13 years, 1273 participants had died. Adjusting for mortality risk markers, higher mortality was associated with noncorrectable visual impairment (hazard ratio [HR], 1.35; 95% confidence interval [CI], 1.04-1.75). This association was stronger for ages younger than 75 years (HR, 2.58; 95% CI, 1.42-4.69). Structural equation modeling revealed greater effects of noncorrectable visual impairment on mortality risk (HR, 5.25; 95% CI, 1.97-14.01 for baseline ages <75 years), with both direct (HR, 2.16; 95% CI, 1.11-4.23) and indirect (HR, 2.43; 95% CI, 1.17-5.03) effects. Of mortality risk markers examined, only disability in walking demonstrated a significant indirect pathway for the link between visual impairment and mortality. Visual impairment predicted mortality by both direct and indirect pathways, particularly for persons younger than 75 years with noncorrectable visual impairment. Disability in walking, which can substantially influence general health, represented a major indirect pathway.

Correctable and non‐correctable visual impairment among young males: a 12‐year prevalence study of the Military Service in Poland

To evaluate the prevalence of correctable and non-correctable visual impairment in a representative sample of young males commissioned for Military Service in Poland. Data concerning vision status was retrospectively reviewed in 969 subjects of European Caucasian origin, most of whom live and have lived in Poland. They were selected from the original database comprising 105017 subjects examined in the period 1993-2004. Based on the age of subjects they were divided into two groups; group I aged 18-24 and group II aged 25-34 years. Visual impairment was defined as distance visual acuity of <20/40 in one or both eyes. Non-correctable impairment was defined as that which was not eliminated by refractive correction. A total of 1938 eyes of 969 white males were examined. There was statistically significant association between rates of visual impairment and increasing age (p < 0.001). Visual impairment was found in 128 (13.2%) subjects in at least one eye. Non-correctable visual impairment was found in 12 (1.2%) subjects. Amblyopia was the main cause, accounting for eight cases (66.67%). Correctable visual impairment was found in the remaining 116 (12.0%) patients. Among them myopia was the most common refractive error and accounted for 75.8%. Differences between age-specific rates of refractive errors were statistically significant (p = 0.003). Appropriate refractive correction improves visual acuity in most subjects presenting with visual impairment. There was a relatively low prevalence of non-correctable visual impairment in a population of young adults in Poland, and this was mainly due to amblyopia.

Correctable and Non-Correctable Visual Impairment in a Population-Based Sample of 12-Year-Old Australian Children

To document the prevalence of correctable and non-correctable visual impairment in a representative sample of Australian children, predominantly age 12 years. Population-based cross-sectional study. Logarithm of the minimum angle of resolution (logMAR) visual acuity was measured in both eyes unaided, with spectacles if worn, and after subjective refraction if required, in 2353 children, examined during 2004 to 2005. Cycloplegic autorefraction (using cyclopentolate) and dilated fundus examination were performed. Using a cut-off of 0.3 logMAR units (<20/40), presenting visual impairment was defined using unaided visual acuity if spectacles were not worn or with usual correction if spectacles were worn. Impairment not eliminated by refraction was considered non-correctable; any difference between this and presenting impairment was defined as correctable impairment. Myopia was defined as spherical equivalent refraction (SER) < or =-0.50 diopters (D), hyperopia as SER > or =+2.0 diopters, anisometropia as SER difference > or =1.00 diopters, and astigmatism as cylinder > or =1.0 diopters. Amblyopia was defined as corrected visual acuity <0.3 logMAR not attributable to an underlying structural eye or visual pathway abnormality. Visual impairment was found in the worse eye of 117 children (5.0%) and comprised correctable (82%) and non-correctable impairment (18%). Correctable impairment was due to myopia in 67 (69.8%), hyperopia in 11 (11.5%) and astigmatism in 32 subjects (33.3%). Causes of non-correctable impairment were: amblyopia 66.7%, congenital glaucoma 9.5%, optic nerve hypoplasia 9.5%, congenital nystagmus 4.8%, and cortical blindness 4.8%. Visual impairment had a relatively low prevalence in this older childhood population, a large proportion of which was correctable by refraction alone.

Assessment of Vision-Related Quality of Life in an Older Population Subsample: The Blue Mountains Eye Study

Purpose: To assess visual functioning and vision-specific health-related quality of life (HRQOL) in an older, community-dwelling-based population subsample, using the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). Methods: Three-quarters (76%, n = 892) of Extension Blue Mountains Eye Study participants (aged ≥ 50 years, mean 60.8 years) completed the self-administered NEI-VFQ-25, an instrument consisting of 12 dimensions and one summary composite score, and comprehensive eye examinations, including monocular distance visual acuity. Visual impairment was defined as visual acuity < 6/12. Unilateral and bilateral visual impairment was defined by the worse eye and better eye, respectively. Correctable visual impairment was defined as that which improved, and non-correctable visual impairment as that which persisted after subjective refraction. Mild visual impairment was defined as visual acuity < 6/12 but ≥ 6/24, moderate as < 6/24 but ≥ 6/60, and severe as < 6/60. Results: There were no significant differences in age, sex, or vision status between NEI-VFQ-25 responders and non-responders. Men had significantly better scores in three subscales than women but there were no significant differences in their overall composite scores (men 88.5± 0.5; women 88.1± 0.4). Persons aged 60–69 years had the best NEI-VFQ-25 profiles (mean composite score ± standard error, 90.2 ± 0.5; 50–59 years, 88.5 ± 0.4; ≥70 years, 86.2 ± 0.8). Presenting bilateral visual impairment (77.1 ± 1.4) was associated with significantly poorer functioning than unilateral (87.5 ± 0.8) or no visual impairment (89.4 ± 0.3). Increasing levels of impairment were associated with poorer levels of visual functioning. The impact of impairment was principally from non-correctable (49.2 ± 2.6) rather than refractive impairments (85.3 ± 1.4), although the latter accounted for over three-quarters (77.5%) of presenting bilateral impairment. Non-correctable unilateral impairment (85.3 ± 1.1) was associated with poorer functioning than no impairment. Conclusions: The findings from this community-dwelling older population show that the NEI-VFQ-25 differentiates well between various levels of visual impairment with regard to the magnitude of their impact on vision-specific quality of life. Greater impacts were noted among persons with bilateral compared to unilateral impairment, with increasing impacts at greater severities of visual impairment. Visual impairment from refractive errors is more frequent than from underlying pathologic disorders, but the impact of correctable visual impairment was considerably milder than the impact of non-correctable visual impairment.

Impact of bilateral visual impairment on health-related quality of life: the Blue Mountains Eye Study.

To assess the impact of visual impairment on health-related quality of life (HRQOL) in an older population and compare it with the impact of major medical conditions. Participants of the second cross-sectional Blue Mountains Eye Study (BMES; n = 3509; mean age, 66.7 years; 57% female) were asked to complete the self-administered 36-item Short-Form health survey (SF-36), a comprehensive interview, and an eye examination. Visual impairment was defined as visual acuity less than 20/40 (better eye). Of 3154 (89.9%) participants with complete data, 172 (5.5%) had visual impairment due to refractive errors (correctable visual impairment) and 66 (2.1%) due to eye conditions (noncorrectable visual impairment; 49 mild, 9 moderate, 8 severe). After adjustment for demographic and medical confounders, there was a trend toward lower SF-36 scores in participants with noncorrectable impairment than in those with correctable impairment (physical component score [PCS] Ptrend = 0.01 and mental component score [MCS] Ptrend = 0.02). Increasingly severe noncorrectable visual impairment was associated with significantly poorer SF-36 scores in all but two dimensions. The impact of noncorrectable visual impairment was comparable to that from major medical conditions (e.g., stroke) and had a greater impact on mental than physical domains (mean MCS = 46.2, PCS = 41). No significant differences in HRQOL were demonstrated between visual impairment cases caused by age-related maculopathy and cataract, after adjusting for severity of visual impairment. Noncorrectable visual impairment was associated with reduced functional status and well-being, with a magnitude comparable to major medical conditions. These data have implications for disability weights such as those developed by the Global Burden of Disease study.

Correctable visual impairment in an older population: the blue mountains eye study

PURPOSE: To describe temporal changes in the characteristics of older persons with visual impairment in their better eye correctable by refraction. DESIGN: Study of two cross sections of a community 6 years apart. METHODS: The Blue Mountains Eye Study examined 3654 persons aged 49 to 97 during 1992 to 1994 (cross-section 1) and 3509 persons (2335 cohort survivors plus 1174 persons who moved to the area and age group) during 1997 to 2000 (cross-section 2). Logarithm of minimal angle of resolution visual acuity was measured before and after refraction. Correctable visual impairment was defined as visual impairment < 20/40 in the better eye before refraction that improved after refraction to no impairment (≥ 20/40). Factors associated with correctable visual impairment and persistent correctable impairment were determined. RESULTS: Cross-sections 1 and 2 had similar age-gender distributions. In cross-section 1, 7.5% of participants had correctable visual impairment, 3.6% had noncorrectable visual impairment, and 88.9% had no impairment. Corresponding rates in cross-section 2 were 5.6%, 2.7%, and 91.7%. In both cross sections, similar proportions (around 68%) of those visually impaired had correctable visual impairment and similar sociodemographic measures predicted correctable visual impairment. Cross-section 1 participants who were married, owned their home, had high job prestige, gained qualifications after high school, or were current drivers were less likely to have correctable visual impairment after controlling for age and gender. Adjusted odds for correctable visual impairment increased in those living alone, using community support services, dependent on others, with myopia, wearing distance glasses, or with low perceived health and heart disease. Histories of stroke, cancer, and diabetes were similar between groups with correctable and no visual impairment. CONCLUSION: Socioeconomic parameters, myopia, wearing distance glasses, reported health problems, and poor perceived health were associated with correctable visual impairment in this older population.

Five-year outcome of correctable visual impairment: the Blue Mountains Eye Study.

This report aims to describe the outcome and socio-economic characteristics of older persons attending the Blue Mountains Eye Study (BMES) with persistent correct-able visual impairment (VI). The BMESI examined 3654 persons aged 49+ during 1992-1994 and re-examined 2335 survivors during 1997-1999 (BMES II). Visual acuity was measured before and after standardized refraction. Participants had correctable VI if their better eye was visually impaired <6/12 before refraction (with distance glasses if worn) and was unimpaired after refraction. In BMES I,274 persons (7.5%) had correctable VI, of whom 127 returned to BMES II. Of this group of 127, 34 had persistent correctable VI and 74 were no longer impaired. Fewer persons with correctable VI returned and more died prior to BMES II, compared to persons with no or non-correctable VI. This study showed that persistent correctable impairment was more frequent with increasing age, among women, in those living alone, using community support services,or with a history of heart disease.