Cortical Visual Impairment

Our study provides the much-needed evidence on causes of childhood blindness in Eritrea. This will assist authorities to plan appropriate strategies and implement preventive, curative, and rehabilitative services to address these causes of vision loss in children in this resource-limited country. This study aims to identify the causes of severe vision impairment and blindness in children attending the only school for the blind in Eritrea. All children enrolled in the school were examined, and the World Health Organization form for the examination of visually impaired children was used to record the data. Examination included visual acuity, refraction, anterior segment, and fundus assessment. Causes of vision loss for children with severe vision impairment (visual acuity <6/60 to 3/60) and blindness (visual acuity <3/60) are reported. Causes were classified by the anatomical site affected and by underlying etiology based on the timing of the insult and causal factor. A total of 92 children were examined, and 71 (77.2%) of them had severe vision impairment and blindness. The major causes of vision loss were corneal scars (16.9%), cataract (12.7%), phthisis bulbi (11.3%), congenital eye deformities (11.3%), optic atrophy (9.3%), and presumed chorioretinal Toxoplasma scars (7.0%). Hereditary factors were the major known etiological category (15.5%) followed by the sequel of eye injuries (12.7%). Blindness due to vitamin A deficiency was not found, whereas infectious causes such as measles and ophthalmia neonatorum were relatively absent (one case each). Potentially avoidable causes of vision impairment were accounted for in 47.9% of children. This study provides the first direct evidence on childhood vision impairment in Eritrea. Despite the limitations, it is clearly shown that nearly half of the vision loss is due to avoidable causes. Thus, preventive public health strategies, specialist pediatric eye care, and rehabilitative services are recommended to address childhood vision impairment in Eritrea.

To assess the prevalence and causes of visual impairment in patients with craniosynostotic syndromes of Apert, Crouzon, Pfeiffer, Saethre-Chotzen and craniofrontonasal dysplasia. The medical records of patients who attended the Craniofacial Clinic at two large paediatric hospitals in Sydney, Australia between 1983 and 2004 were retrospectively reviewed. Presenting visual acuity (VA) was assessed using tests appropriate to age and cognition: 'fix and follow' in infants (<18 months old), Teller card acuity in preverbal children (18 months to less than 3 years old), Kay picture test or Sheridan-Gardiner test in children aged between 3 and less than 6 years and Snellen chart in those aged 6 years or older. Visual impairment was defined as the inability to fix and follow or presenting VA < 6/12 in the better eye. Amblyopia was defined as a two-line difference in VA between both eyes in the absence of an organic eye disease. Sixty-three patients with craniosynostotic syndromes were identified, of whom 55 had VA assessed at the first visit. Of these 55, 19 (35.5%) had bilateral visual impairment and 5 (9.1%) had unilateral visual impairment. Causes of visual impairment include amblyopia (16.7%), ametropia (25%), optic atrophy (16.7%) and exposure keratopathy (4.2%). Risk factors for amblyopia include strabismus (43.3%), astigmatism (> or =1.5 dioptres) (39.5%), hypermetropia (18.4%) and anisometropia (> or =1.5 dioptre difference between both eyes) (15.8%). Six of the 63 patients (9.5%) had papilloedema; those who were followed up showed gradual resolution of papilloedema following timely decompressive surgery. A high prevalence of visual impairment in patients with craniosynostotic syndromes was found, almost half of them due to potentially correctable causes, including amblyopia and ametropia. Optic atrophy remains an important cause of visual impairment. Further studies are needed to assess the timing and efficacy of intervention for modifiable causes of visual loss in craniosynostotic syndromes.

Purpose:This was a population-based study to determine the prevalence and causes of visual impairment in children less than 16 years in Urban North India.Methods:This cross-sectional study was conducted in 40 clusters of urban Delhi. 20,955 children aged less than 16 years underwent visual acuity screening using age-appropriate visual acuity charts. Unaided visual acuity of enumerated children aged over 2 years was assessed by using Lea symbols chart in 3-5 years age group and logMAR tumbling E charts for the 6-15 years age group. For children aged 0-2 years, fixation and following to torch light was assessed. All the children with unaided visual acuity of <6/12 in any eye in age group 3–15 years and inability to follow the light in age <3 years were referred for detailed ophthalmic examination.Results:Amongst 20,955 children examined for visual acuity a total of 789 children were referred to the central clinic for detailed ophthalmic examination. Of these referred children, a total of 124 had presenting visual acuity <6/18 in the better eye. The prevalence of visual impairment (VI) was 5.92 per thousand (95% CI: 4.96-7.05). The prevalence of moderate to severe visual impairment was maximum in the age group of 11 to 15 years. The main cause of avoidable VI in these children was a refractive error (75.7%). The prevalence of blindness was 0.42 per thousand.Conclusion:Optic nerve abnormalities were the most important cause of blindness in children. Refractive error is the most important cause of visual impairment amongst children and needs to be addressed.

Changes in visual cortex excitability in blind subjects as demonstrated by transcranial magnetic stimulation. Gothe J, Brandt SA, Irlbacher K, Roricht S, Sabel BA, Meyer B-U. Brain 2002;125:479–490.

Visual performance and brain structures in the developing brain of pre-term infants

BackgroundChildhood blindness and low vision have become major public health problems in developing countries. The purpose of this study was to categorise the causes of visual impairment according to aetiology and provide detailed local information on visually impaired children seeking low‐vision services in a tertiary eye centre in Nepal.MethodsA retrospective study was conducted of all visually impaired children (visual acuity of less than 6/18 in the better eye), aged less than 17 years seen in the low‐vision clinic at the Sagarmatha Chaudhary Eye Hospital in Lahan between January 1, 2012 and December 31, 2013.ResultsOf the 558 visually impaired children, the majority were males, 356 (63.7 per cent). More than half (56.5 per cent) of the children were in the 11 to 16 years age group. Many of the low‐vision children (52.9 per cent) were identified as having moderate visual impairment (visual acuity less than 6/18 to 6/60). Most children were diagnosed with childhood (36.2 per cent) or genetic (35.5 per cent) aetiology, followed by prenatal (22.2 per cent) and perinatal (6.1 per cent) aetiologies. Refractive error and amblyopia (20.1 per cent), retinitis pigmentosa (14.9 per cent) and macular dystrophy (13.4 per cent) were the most common causes of paediatric visual impairment. Nystagmus (50.0 per cent) was the most common cause of low vision in the one to five years age group, whereas refractive error and amblyopia were the major causes in the six to 10 and 11 to 16 years age group (17.6 and 22.9 per cent, respectively). Many of the children (86.0 per cent) were prescribed low‐vision aids and 72.0 per cent of the low‐vision aid users showed an improvement in visual acuity either at distance or near.ConclusionPaediatric low vision has a negative impact on the quality of life in children. Data from this study indicate that knowledge about the local characteristics and aetiological categorisation of the causes of low vision are essential in tackling paediatric visual impairment. The findings also signify the importance of early intervention to ensure a better quality of life.

Emmetropization is the reduction in neonatal refractive errors that occurs after birth. Ocular disease may affect this process. We aimed to determine the relative frequency of ocular conditions causing vision impairment in the pediatric population and characterize the refractive anomalies present. We also compared the causes of vision impairment in children today to those between 1974 and 1981. Causes of vision impairment and refractive data of 872 children attending a pediatric low-vision clinic from 1985 to 2002 were retrospectively collated. As a result of associated impairments, refractive data were not available for 59 children. An analysis was made of the causes of vision impairment, the distribution of refractive errors in children with vision impairment, and the average type of refractive error for the most commonly seen conditions. We found that cortical or cerebral vision impairment (CVI) was the most common condition causing vision impairment, accounting for 27.6% of cases. This was followed by albinism (10.6%), retinopathy of prematurity (ROP; 7.0%), optic atrophy (6.2%), and optic nerve hypoplasia (5.3%). Vision impairment was associated with ametropia; fewer than 25% of the children had refractive errors < or = +/-1 D. The refractive error frequency plots (for 0 to 2-, 6 to 8-, and 12 to 14-year age bands) had a Gaussian distribution indicating that the emmetropization process was abnormal. The mean spherical equivalent refractive error of the children (n = 813) was +0.78 +/- 6.00 D with 0.94 +/- 1.24 D of astigmatism and 0.92 +/- 2.15 D of anisometropia. Most conditions causing vision impairment such as albinism were associated with low amounts of hyperopia. Moderate myopia was observed in children with ROP. The relative frequency of ocular conditions causing vision impairment in children has changed since the 1970s. Children with vision impairment often have an associated ametropia suggesting that the emmetropization system is also impaired.

Background: There are currently two versions of rapid assessment of avoidable blindness (RAAB) method in use: RAAB5 and RAAB6. While RAAB5 uses visual acuity (VA) of 6/18 as cutoff for visual impairment (VI), RAAB6 uses VA of 6/12. Aim: The aim of the study was to determine the average additional time it will take to test from 6/18 to 6/12 VA levels and to compare the causes of VI across these VA cutoffs. Methods: It was a cross-sectional study of patients aged 50 years and above attending a tertiary hospital in Jos between April and September 2016 (6 months). RAAB6 methodology was used to test presenting VA of all participants. The time taken to obtain a VA of 6/18 and to test from 6/18 to 6/12 was recorded separately for each eye. Those with VA worse than 6/12 in one or both eyes had their eyes examined to determine the cause of VI. The data collected were analyzed using the Statistical Package for Social Sciences for windows software, version 20. Results: The average additional time taken to test VA from 6/18 to 6/12 was 42.11 seconds (95% confidence interval: 32.86–51.35). Cataract was the major cause of VI with both VA cutoffs with no significant difference in its proportion (P = 0.924). Uncorrected refractive error and glaucoma were the next important causes of VI with 6/12 (P = 0.041) and 6/18 (P = 0.041) cutoffs, respectively. Conclusion: The spectrum of disease causing VI may not differ significantly between the two RAAB versions, but survey duration will likely be prolonged with RAAB6.

PurposeEpidemiologic evaluation and investigating the causes of visual impairment in any society is a matter of concern and has a direct effect on the country's health care planning. In this study we describe causes of low vision and blindness in Iranian patients referred to rehabilitation clinics for taking vision aids.MethodsIn this cross-sectional study, visual acuity was classified based on best-corrected visual acuity in the better eye according to the World Health Organization definition (blindness, visual acuity [VA] < 20 / 400; severe visual impairment, VA < 20 / 200-20 / 400; mild to moderate visual impairment, VA < 20 / 60-20 / 200). The causes of blindness and low vision were determined using the 10th version of International Classification of Diseases based on the main cause in both eyes. To describe data, we used mean ± SD and frequency.ResultsThe study included 432 patients, 65% male, with a mean age of 43.6 ± 25.5 years (range, 3 to 92 years). Mild to moderate visual impairment, severe visual impairment and blindness were present in 122 (28.8%), 196 (46.4%) and 105 (24.8%) of the patients, respectively. The main causes of visual impairment were retinal and choroidal diseases (74.5%), optic nerve and optic tract diseases (9.8%), vitreous and globe disorders (5.3%), congenital cataract (3.1%), and glaucoma (2.6%). The distribution pattern of the causes was similar in all age subgroups.ConclusionsDiseases of the retina and choroid are the main cause of visual impairment among patients referredto an academic visual rehabilitation clinic in Iran.

To describe the prevalence of visual impairment/blindness among older adults aged > or = 50 years in rural populations in Shandong Province, China. Population-based, cross-sectional study was designed in this survey. Three counties and one suburbs representative of the different levels of socioeconomic development were selected as the study areas within the province from April to July 2008. Geographically defined cluster sampling was used in randomly selecting a cross-section of residents aged > or = 50 years from each county. Eligible persons were invited to local examination sites for visual acuity (VA) testing and eye examination. Those presenting with VA < or = 0.5 in either eye were refracted to achieve best-corrected VA. Chi2-test was used to compare the prevalence of blindness and visual impairment in the different groups. Multiple logistic regressions were used to investigate the association of age, gender, education, and county with presenting and best-corrected visual impairment and blindness. Adjusted odds ratio was used to compare the prevalence of blindness and visual impairment in the different counties. Of 19 583 enumerated eligible persons, 17 816 (90.98%) were examined and tested for VA. The prevalence of presenting visual impairment (0.05- < 0.3) in the better-seeing eye was 7.01% (the age-standardized rate was 6.56%) and presenting blindness (< 0.05) was 1.58% (the age-standardized rate was 1.48%). Across the 4 counties, presenting visual impairment ranged from 4.51% to 8.65%, and presenting blindness from 1.35% to 1.77%. With best-corrected VA, the prevalence of visual impairment was 3.66% (the age-standardized rate was 3.38%), and 1.33% for blindness (the age-standardized rate was 1.24%). The ranges across the 4 counties were 2.63% to 4.38% for visual impairment and 1.06%-1.54% for blindness. The prevalence of visual impairment with presenting VA was higher than that with best-corrected VA (2 = 201.262, P = 0.000). There was no significant difference between the prevalence of blindness with presenting VA and that with best-corrected VA (Chi2 = 0.117, P = 0.732). Based on both presenting and best-corrected VA, visual impairment and blindness were associated with older age, female gender, lack of education, and county (P < or = 0.05). Visual impairment and blindness are important public health problems in rural older adults aged > or = 50 years in Shandong Province. Un-corrected refractive error is one of the main causes of visual impairment.

Hypoxic-ischemic injury to the periventricular cerebral white matter [periventricular leukomalacia (PVL)] results in cerebral palsy and is the leading cause of brain injury in premature infants. The principal feature of PVL is a chronic disturbance of myelination and suggests that oligodendrocyte (OL) lineage progression is disrupted by ischemic injury. We determined the OL lineage stages at risk for injury during the developmental window of vulnerability for PVL (23-32 weeks, postconceptional age). In 26 normal control autopsy human brains, OL lineage progression was defined in parietal white matter, a region of predilection for PVL. Three successive OL stages, the late OL progenitor, the immature OL, and the mature OL, were characterized between 18 and 41 weeks with anti-NG2 proteoglycan, O4, O1, and anti-myelin basic protein (anti-MBP) antibodies. NG2+O4+ late OL progenitors were the predominant stage throughout the latter half of gestation. Between 18 and 27 weeks, O4+O1+ immature OLs were a minor population (9.9 +/- 2.1% of total OLs; n = 9). Between 28 and 41 weeks, an increase in immature OLs to 30.9 +/- 2.1% of total OLs (n = 9) was accompanied by a progressive increase in MBP+ myelin sheaths that were restricted to the periventricular white matter. The developmental window of high risk for PVL thus precedes the onset of myelination and identifies the late OL progenitor as the major potential target. Moreover, the decline in incidence of PVL at approximately 32 weeks coincides with the onset of myelination in the periventricular white matter and suggests that the risk for PVL is related to the presence of late OL progenitors in the periventricular white matter.

To evaluate and analyze the causes of visual impairment, handicap, and blindness in a tertiary eye hospital among patients applying blindness certificates in Chennai. Applications for blindness certificates were analyzed over two years (2019-2021). The main cause of blindness, visual handicap, and visual impairment in these applications was ascertained by age group and etiology. Visual impairment disability percentages and definitions proposed by the Government of India [category 0-4, 20-100%] were used to categorize and give a percentage to all applicants. Results were compared with data from studies on blindness certificates and population-based studies. A total of 118 applications were reviewed. The mean age was 23.5±7.9 (range 12 to 65 years). The most common causes of blindness were retinitis pigmentosa and optic atrophy. In the age group 0-15 years, phthisis bulbi followed by microphthalmos were found to be the most common cause of blindness. Among the 15-30 years age group, macular pathology was the most common cause of visual blindness. Between 30-40 years of age group Retinitis pigmentosa is most common. Above 40-60 years of age, optic atrophy and glaucoma were the most common cause of blindness. Data from applications for blindness certificates provide valuable information regarding different causes of visual blindness provide an insight into the overall trends in disease profile and service delivery.

AIMS To describe the causes of bilateral and unilateral blindness and visual impairment in two cross-sections of an older Australian population 6 years apart. METHODS The Blue Mountains Eye Study examined 3654 persons aged 49-97 years during 1992-1994 (population cross-section 1). Cohort survivors (2335) and 1174 persons who moved to the area or reached an eligible age were examined during 1997-2000, a total of 3509 persons (population cross-section 2). LogMAR visual acuity was measured after standardized refraction. Blindness and visual impairment were respectively defined by visual acuity <6/60 and <6/12. Causes were determined for the two temporal cross-sections. RESULTS Age-related macular degeneration (AMD) was the principal cause of bilateral and unilateral non-correctable blindness in both cross-sections. AMD caused 77% of bilateral blindness in Cross-section 1 and 50% in Cross-section 2. Cataract, glaucoma, corneal and neurological disease were next equally frequent causes (6% each) of bilateral blindness in Cross-section 1. In Cross-section 2, cataract ranked as the third most frequent principal cause (10%) after other retinal diseases (40%). The proportion of unilateral blindness with AMD as principal cause was very similar (around one-third of cases) in the two cross-sections; while in Cross-section 2 blindness was less frequently caused by cataract (19% vs. 13%). Cataract was the principal cause of both bilateral and unilateral visual impairment, responsible for 50% of bilateral (better eye) and 35-40% of unilateral (worse eye) impairment, with slightly lower rates found in Cross-section 2 than in Cross-section 1. AMD was consistently the second most frequent cause, causing one-third of bilateral and one-fifth of unilateral visual impairment. CONCLUSIONS These data indicate a relative stable pattern of causes for blindness and visual impairment, with AMD and cataract, respectively, dominating these two levels.

PurposeTo assess the prevalence and causes of visual impairment and blindness in a Central European country. The findings may have implications for the planning of further research and development of therapies in order to prevent blindness.SettingDepartment of Ophthalmology, Medical University of Graz, Austria.DesignRetrospective, epidemiological study.MethodsThe database of the Main Confederation of Austrian Social Insurances was searched for patients with visual impairment, legal blindness or deaf-blindness. This database gathers data from patients of all insurance providers in the country who receive care due to visual impairment and blindness. To determine the prevalence of these conditions, the number of all entries recorded in February 2019 was evaluated. Additionally, all new entries between (January 1st,) 2017, and (December 31st,) 2018, were analysed for distinct characteristics, such as sex, the cause of blindness/visual impairment, and age. Since health care allowances can provide a considerable source of income (459.90€-936.90€ per month), good coverage of practically all patients who are blind and visually impaired in the country can be assumed.ResultsOn February 2nd, 2019, 17,730 patients with visual impairments, blindness or deaf-blindness were registered in Austria, resulting in a prevalence of these diagnoses of 0.2% in the country. During the observational period from 2017 to 2018, 4040 persons met the inclusion criteria. Of these, 2877 were female (65.3%), and 1527 were male (34.7%). The mean age was 75.7 ± 18.0 years (median 82). Most patients (n = 3675, 83.4%) were of retirement age, while 729 (16.6%) were working-age adults or minors. In total, an incidence of 25.0 (95% confidence limit (CL) 24.3–25.8) per 100,000 person-years was observed from 2017 to 2018. A higher incidence was observed for females (32.2, 95% CL 31.0–33.3) than for males (17.7, 95% CL 16.8–18.5). Incidences where higher for males in lower age groups (e.g. 10–14 years: rate ratio RR = 2.7, 95% CL 1.1–6.8), and higher for females in higher age groups (e.g. 70–74 years: RR = 0.6, 95% CL 0.5–0.8). In total, the most frequent diagnoses were macular degeneration (1075 persons, 24.4%), other retinal disorders (493 persons, 11.2%) and inherited retinal and choroidal diseases (IRDs) (186 persons, 4.2%). Persons with IRDs were significantly younger compared to persons with macular degeneration or retinal disorders (IRDs: median 57, range 2–96 vs 83, 5–98 and 82, 1–98 years, p<0.001). For persons of retirement age, macular degeneration, other retinal disorders and glaucoma were the three most frequent diagnoses. In contrast, among working-aged adults and children, IRDs were the leading cause of visual impairment and blindness (103 persons, 14.1%).ConclusionThese data show that IRDs are the leading cause of blindness and visual impairment in working-aged persons and children in Austria. Thus, these findings suggest to draw attention to enhance further research in the fields of emerging therapies for IRDs.

Cranial Ultrasonography