RETINITIS PIGMENTOSA ASSOCIATED WITH THE EYS C2139Y VARIANT : An Important Cause of Blindness in East Asian Populations

PURPOSE

The study aimed to describe the phenotypic features of retinitis pigmentosa (RP) associated with the previously described EYS C2139Y variant in Singaporeans and establish the importance of this variant as a prevalent cause of RP among East Asians.

METHODS

A clinical phenotyping and exome-sequencing study was conducted on consecutive patients with nonsyndromic RP. Epidemiological analysis was performed using Singaporean and global population-based genetic data.

RESULTS

A study of 150 consecutive unrelated individuals with nonsyndromic RP found that 87 (58%) of cases had plausible genotypes. A previously described missense variant in the EYS gene, 6416G>A (C2139Y), occurred heterozygously or homozygously in 17 of 150 families (11.3%), all with autosomal recessive RP. Symptom onset in EYS C2139Y-related RP ranged from 6 to 45 years, with visual acuity ranging from 20/20 at 21 years to no light perception by 48 years. C2139Y-related RP had typical findings, including sectoral RP in cases with EYS E2703X in trans . The median age at presentation was 45 years and visual fields declined to less than 20° (Goldmann V4e isopter) by age 65 years. Intereye correlation for visual acuity, fields, and ellipsoid band width was high (r 2 = 0.77-0.95). Carrier prevalence was 0.66% (allele frequency of 0.33%) in Singaporean Chinese and 0.34% in East Asians, suggesting a global disease burden exceeding 10,000 individuals.

CONCLUSION

The EYS C2139Y variant is common in Singaporean RP patients and other ethnic Chinese populations. Targeted molecular therapy for this single variant could potentially treat a significant proportion of RP cases worldwide.

Cataract Surgical Coverage and Visual Acuity Outcomes in Rural China in 2014 and Comparisons With the 2006 China Nine-Province Survey

PURPOSE

To estimate surgical coverage of cataract-related vision impairment and blindness and visual acuity outcomes in operated eyes in rural China in 2014 with comparisons with the 2006 Nine-Province Survey.

DESIGN

Population-based, cross-sectional study.

METHODS

Geographical cluster sampling was used in randomly selecting residents from a rural county or semi-rural district within 9 provinces: Beijing, Jiangsu, Guangdong, Heilongjiang, Jiangxi, Hebei, Ningxia, Chongqing, and Yunnan. Persons 50 years of age or older were enumerated through household visits and invited to examination sites for visual acuity testing and ocular examination. Surgical coverage and visual acuity outcomes in 2014 were compared with data from the 2006 survey.

RESULTS

Among 51 310 examined persons, surgical coverage among those presenting with cataract-related severe visual impairment or blindness (<20/200) was 62.7% overall, ranging from 43.4% to 83.6% across the 9 study sites. Unoperated cataract was significantly associated with older age, female sex, and lack of education. Presenting visual acuity outcomes ≥ 20/63 in cataract-operated eyes was 62.2% overall, ranging from 51.6% to 78.6%, and 75.2%, ranging from 67.1% to 81.5%, with best-corrected visual acuity. As a proportional percentage of cataract surgical coverage in 2006, overall surgical coverage increased by 81.4% during the 2006-2014 interval, and by 110% when adjusted for visual acuity outcomes ≥ 20/63.

CONCLUSIONS

Cataract blindness control is well underway in rural China, as evidenced by significant increases in cataract surgical coverage and improvement in visual acuity outcomes during the 2006-2014 interval. Further efforts are needed to provide greater access to affordable cataract surgery for the elderly, female persons, and those with little or no education.

Cross-sectional study on prevalence, causes and avoidable causes of visual impairment in Maori children

AIMS

To provide information and comparison pertaining to visual impairment of Maori children with other children in New Zealand in particular: prevalence of blindness, causes of visual impairment, and avoidable causes of visual impairment.

METHODS

Retrospective data collection utilising the WHO/PBL eye examination record for children with blindness and low vision at Blind and Low Vision Education Network New Zealand (BLENNZ), Homai. Individuals not of Maori ethnicity or over the age of 16 were excluded from the study.

RESULTS

106 blind and 64 low-vision Maori children were studied. The main cause of blindness in Maori children is cortical visual impairment. Twenty-eight percent of causes of blindness in this population are potentially avoidable with non-accidental injury as the main cause.

CONCLUSION

The prevalence of blindness and low vision in children amounts to 0.05% and 0.03%, respectively. The prevalence and causes of childhood blindness are comparable to the other ethnic groups in New Zealand. The main difference lies in avoidable causes of blindness, which appeared to be much higher in the Maori population. The leading cause of avoidable blindness in Maori children is caused by non-accidental injuries.

Prevalence and causes of visual impairment and blindness in an urban Indian population: the Singapore Indian Eye Study

PURPOSE

To describe the prevalence and causes of visual impairment and blindness in an urban Indian population.

DESIGN

Population-based study.

PARTICIPANTS

Ethnic Indians aged more than 40 years living in Singapore.

METHODS

Participants underwent standardized ophthalmic assessments for visual impairment and blindness, defined using best-corrected visual acuity (BCVA) and presenting visual acuity (PVA), according to US and modified World Health Organization (WHO) definitions.

MAIN OUTCOME MEASURES

Unilateral visual impairment or blindness was defined on the basis of the worse eye, and bilateral visual impairment or blindness was defined on the basis of the better eye. Primary causes of visual impairment were determined.

RESULTS

A total of 3400 eligible individuals (75.6% response rate) participated. On the basis of US definitions, the age-standardized prevalence was 0.4% for bilateral blindness (≤20/200, better eye) and 3.4% for bilateral visual impairment (<20/40 to >20/200, better eye). Another 0.3% of bilateral blindness and 13.4% of bilateral visual impairment were correctable with refraction. Cataract was the principal cause of best-corrected bilateral blindness (60.0%) and bilateral visual impairment (65.7%). Other major causes of blindness and visual impairment included diabetic retinopathy, age-related macular degeneration, glaucoma, corneal opacity, and myopic maculopathy.

CONCLUSIONS

The prevalence of bilateral blindness and visual impairment in Indians living in Singapore is lower than estimates from populations living in India, but similar to estimates obtained from Singapore Malay and Chinese populations. Cataract is the leading cause of blindness and visual impairment. One in 20 cases of bilateral blindness and 1 in 10 cases of bilateral visual impairment are attributable to diabetic retinopathy. These data may have relevance to many ethnic Indian persons living outside India.

Do blind people see race? Social, legal, and theoretical considerations

Although the meaning, significance, and definition of race have been debated for centuries, one thread of thought unifies almost all of the many diverging perspectives: a largely unquestioned belief that race is self-evident and visually obvious, defined largely by skin color, facial features, and other visual cues. This suggests that “seeing race” is an experience largely unmediated by broader social forces; we simply know it when we see it. It also suggests that those who cannot see are likely to have a diminished understanding of race. But is this empirically accurate?I examine these questions by interviewing people who have been totally blind since birth about race and compare their responses to sighted individuals. I not only find that blind people have as significant an understanding of race as anyone else and that they understand race visually, but that this visual understanding of race stems from interpersonal and institutional socializations that profoundly shape their racial perceptions. These findings highlight how race and racial thinking are encoded into individuals through iterative social practices that train people to think a certain way about the world around them. In short, these practices are so strong that even blind people, in a conceptual sense, “see” race. Rather than being self-evident, these interviews draw attention to how race becomes visually salient through constitutive social practices that give rise to visual understandings of racial difference for blind and sighted people alike. This article concludes with a discussion of these findings' significance for understanding the role of race in law and society.

Assessment of visual status of the Aeta, a hunter-gatherer population of the Philippines (an AOS thesis)

PURPOSE

A screening study was performed to assess levels of visual impairment and blindness among a representative sample of older members of the Aeta, an indigenous hunter-gatherer population living on the island of Luzon in the Philippines.

METHODS

Unrelated older Aeta couples were randomly invited to participate in a visual screening study. All consented individuals had ocular history, medical history, complete ophthalmic examination, height, weight, and blood pressure taken.

RESULTS

A total of 225 individuals were screened from 4 villages. Visual acuity, both uncorrected and pinhole corrected, was significantly worse among older vs younger age-groups for women, men, and when combined (P < .001). Visual impairment was present in 48% of uncorrected and 43% of pinhole corrected eyes in the oldest age-group. Six percent of the screened population was bilaterally blind. The major causes of blindness were readily treatable. The most common etiologies as a proportion of blind eyes were cataract (66%), refractive error (20%), and trauma (7%). No cases of primary open-angle, primary angle-closure, or exfoliation glaucoma were observed in this population.

DISCUSSION

Visual impairment and blindness were common in the Aeta population. Primary forms of glaucoma, a major cause of blindness found in most population-based studies, were not observed. The absence of primary glaucoma in this population may reflect random sampling error. However, based on similar findings in the Australian Aborigine, this raises the possibility that these two similar populations may share genetic and/or environmental factors that are protective for glaucoma..

Six-Year Incidence of Visual Loss in African Americans With Type 1 Diabetes Mellitus

OBJECTIVE

To report the 6-year incidence of visual loss and associated risk factors in African Americans with type 1 diabetes mellitus.

METHODS

African Americans with type 1 diabetes (n=483) who participated in the New Jersey 725 study were reexamined as part of a 6-year follow-up. Best-corrected visual acuity, a structured clinical interview, fundus photographs, and blood pressure measurements were obtained. The biological evaluation included blood and urine assays. Any visual loss was defined as a visual acuity of 20/40 or worse in the better eye, blindness as a visual acuity of 20/200 or worse in the better eye, and doubling of the visual angle (DVA) as the loss of 15 or more letters between the first and second visits.

RESULTS

Over 6 years, 19 of 440 patients (4.3%) developed visual loss in the better eye, 3 of 472 patients (0.6%) became blind, 47 of 481 patients (9.8%) developed DVA in the better eye, and 65 of 481 (13.5%) developed DVA in either eye. Baseline older age, high glycosylated hemoglobin level, retinopathy severity, and proteinuria were characteristics significantly (P<.001 for all) and independently associated with DVA in either eye at follow-up.

CONCLUSIONS

The 6-year incidence of DVA in either eye (13.5%) is high in African Americans with type 1 diabetes. Baseline poor glycemic control, diabetic retinopathy severity, proteinuria, and older age are predictors of visual loss in this population.

Behcet disease in adult Druzes in north Israel: the influence of ethnic origin on disease expression and severity

BACKGROUND

Behcet's disease (BD) is known to vary in severity and manifestations in different populations.

OBJECTIVE

In an attempt to sort out genetic and environmental influences on disease expression, we carried out a study to assess the clinical features of BD in the adult Druze and Arab populations in north Israel, comparing 2 disparate ethnic groups of similar genetic background inhabiting the same geographic region.

METHODS

We compared 23 Druze and 30 Arab patients with BD. All patients fulfilled the classification criteria of the International Study Group for BD.

RESULTS

Manifestations were similar in 2 groups. The most frequent BD manifestations among the Druzes were recurrent oral aphthae (100%) and genital aphthae (61%) versus 100% and 53% in Arab patients, followed by inflammatory ocular involvement, 65% versus 53%, respectively. Arthritis was noted in 39% of Druze, with 27% in Arabs. Anterior uveitis occurred in 9 Druze patients (48%) and panuveitis in 4, with no case of blindness when compared with 30% with anterior uveitis, 4 with panuveitis, and 4 cases of blindness (P < 0.04) among the Arabs. One Druze BD patient had deep vein thrombosis versus 8 Arab patients (P < 0.017). No pulmonary embolism, aortic aneurysm, nor valvular involvement was documented in the Druze versus 1 case of each in Arabs. No case of neuro-Behcet was reported in Druzes versus 6 cases of neuro-Behcet among Arabs (P < 0.023). The severity score was 4.0 (SD, 1.2) in Druze and 5.8 (SD, 1.9) in Arabs (P = 0.0004). The prevalence of HLA B51 did not differ significantly between the groups.

CONCLUSION

Druze BD patients in Israel have a milder disease than do Arabs, similar to observations in familial Mediterranean fever. Druze BD patients had significantly less severe ocular disease and neurologic manifestations. Our results suggest an ethnic influence on expression of BD not related to HLA B 51.

Novel Mutations in Norrie Disease Gene in Japanese Patients with Norrie Disease and Familial Exudative Vitreoretinopathy

PURPOSE

To search for mutations in the Norrie disease gene (NDP) in Japanese patients with familial exudative vitreoretinopathy (FEVR) and Norrie disease (ND) and to delineate the mutation-associated clinical features.

METHODS

Direct sequencing after polymerase chain reaction of all exons of the NDP gene was performed on blood collected from 62 probands (31 familial and 31 simplex) with FEVR, from 3 probands with ND, and from some of their family members. The clinical symptoms and signs in the patients with mutations were assessed. X-inactivation in the female carriers was examined in three FEVR families by using leukocyte DNA.

RESULTS

Four novel mutations-I18K, K54N, R115L, and IVS2-1G-->A-and one reported mutation, R97P, in the NDP gene were identified in six families. The severity of vitreoretinopathy varied among these patients. Three probands with either K54N or R115L had typical features of FEVR, whereas the proband with R97P had those of ND. Families with IVS2-1G-->A exhibited either ND or FEVR characteristics. A proband with I18K presented with significant phenotypic heterogeneity between the two eyes. In addition, affected female carriers in a family harboring the K54N mutation presented with different degrees of vascular abnormalities in the periphery of the retina. X-inactivation profiles indicated that the skewing was not significantly different between affected and unaffected women.

CONCLUSIONS

These observations indicate that mutations of the NDP gene can cause ND and 6% of FEVR cases in the Japanese population. The X-inactivation assay with leukocytes may not be predictive of the presence of a mutation in affected female carriers.

Association of the Asn306Ser variant of the SP4 transcription factor and an intronic variant in the beta-subunit of transducin with digenic disease

PURPOSE

SP4 is a transcription factor abundantly expressed in retina that binds to the GC promoter region of photoreceptor signal transduction genes. We have previously shown that SP4 may be involved in the transcriptional activation of these genes alone or together with other transcription factors such as SP1, neural retina leucine zipper protein (NRL), and cone-rod homeobox gene (CRX). Since mutations in NRL and CRX are involved in inherited retinal degenerations, SP4 was considered a good candidate for mutation screening in patients with this type of diseases. The purpose of this work, therefore, was to investigate possible mutations in SP4 in a cohort of patients affected with different forms of retinal degenerations.

METHODS

270 unrelated probands with various forms of retinal degeneration including autosomal dominant and autosomal recessive retinitis pigmentosa (RP), autosomal dominant and autosomal recessive cone-rod dystrophy (CRD), and Leber's congenital amaurosis (LCA), were screened for mutations in the SP4 gene. Single strand conformation polymorphism (SSCP) analysis was performed on the six SP4 gene exons including flanking regions followed by direct sequencing of SSCP variants.

RESULTS

Nine different sequence variants were found in 29 patients, four in introns and five in exons. Many of the probands were previously screened for mutations in the genes encoding the alpha-, beta- and gamma-subunits of rod-specific cGMP phosphodiesterase (PDE6A, PDE6B, PDE6G), the beta-subunit of rod-specific transducin (GNB1), and peripherin/rds (RDS). One group of seven probands of Hispanic background that included five with arRP, one with RP of unknown inheritance (isolate) and 1 with arCRD carried an Asn306Ser mutation in SP4. Of the seven, the isolate case was homozygous and the other 6 heterozygous for the variant. Two arRP and the arCRD probands carried an additional intronic GNB1 variant. DNA from the family members of the arCRD proband could not be obtained, but for the other two families, all affected members and none of the unaffected carried both the SP4 Asn306Ser allele and the GNB1 intronic variant.

CONCLUSIONS

If mutations in SP4 do cause retinal degenerative disease, their frequency would be low. While digenic disease with the SP4 Asn306Ser and the GNB1 intronic variant alleles has not been established, neither has it been ruled out. This leaves open the possibility of a cooperative involvement of SP4 and GNB1 in the normal function of the retina.

Association between Vision Loss and Higher Medical Care Costs in Medicare Beneficiaries

PURPOSE

To identify the cost to the Medicare program for patients with either stable or progressive vision loss and to estimate the impact on eye-related and non-eye related care.

DESIGN

Retrospective cohort study.

PARTICIPANTS

The study population was Medicare beneficiaries included in the standard 5% analytic sample and continuously enrolled from 1999 to 2003, excluding Medicare managed-care enrollees.

METHODS

Vision loss was categorized as moderate loss, severe loss, and blindness, based on International Classification of Diseases 9, Clinical Modification codes.

MAIN OUTCOME MEASURES

Average yearly cost of eye-related and non-eye related medical care during 1999 to 2003, in 2003 dollars.

SECONDARY OUTCOMES

(1) depression, (2) injury, (3) skilled nursing facility (SNF) utilization, and (4) long-term care facility (LTC) admission.

RESULTS

Compared with patients with normal vision, excess adjusted mean eye-related costs were 345 dollars, 407 dollars, and 237 dollars annually for those with moderate loss, severe loss, and blindness, respectively; annual excess non-eye related costs were 2193 dollars, 3301 dollars, and 4443 dollars, respectively. At each level of vision loss, those progressing from a presumably normal state at baseline incurred higher Medicare costs than those with that level of vision loss at baseline. Any degree of progressive vision loss was associated with an increased risk of depression, injury, SNF utilization, and LTC admission. Identifiable costs attributable to these complications explained 27% to 41% of the excess costs associated with vision loss.

CONCLUSIONS

Medicare beneficiaries with coded diagnoses of vision loss incur significantly higher costs than those with normal vision, and approximately 90% of these costs are non-eye related medical costs. Extrapolating to the entire Medicare population, blindness and vision loss are associated with $2.14 billion in 2003 non-eye related medical costs. Preventing vision loss is not only a medical imperative but also an economic one.

Natural history of the visual impairment of relapsing neuromyelitis optica

PURPOSE

To describe the clinical features and natural history of the visual impairment of relapsing neuromyelitis optica.

DESIGN

Prospective observational case series.

PARTICIPANTS

Thirty patients of Afro-Caribbean origin with neuromyelitis optica and 47 patients with multiple sclerosis.

METHODS

A complete ophthalmologic examination was performed with each ocular attack and during a remission period at least 6 months after the last attack.

MAIN OUTCOME MEASURES

Incidence of unilateral and bilateral optic neuritis and incidence of unilateral and bilateral severe visual loss, defined as visual acuity (VA) < or = 20/200.

RESULTS

Twenty-eight patients (93%) with neuromyelitis optica were female and 2 (7%) were male. The mean age of onset was 30+/-10.5 years. Mean disease duration was 9.5+/-5.4 years. Neuromyelitis optica first manifested by an episode of optic neuritis in 23 cases (76.6%), bilateral in 4. The average number of ocular attacks per patient was 2.7+/-1.6. Twenty-one patients (70%) showed impairment in both eyes. Median times from onset to unilateral optic neuritis, bilateral optic neuritis, mono-ocular severe visual loss, and binocular severe visual loss were 0+/-0.08, 1+/-1.6, 2+/-0.8, and 13+/-3 years, respectively. Fifteen patients (50%) experienced severe visual loss in both eyes and 6 (20%) in one eye. Severe visual loss occurred in as few as 2 attacks.

CONCLUSION

This study is the largest series of relapsing neuromyelitis optica in a population of African descent. Neuromyelitis optica's visual impairment is very severe; it contrasts drastically with that typically observed in multiple sclerosis. We confirmed that the prognosis for optic neuritis in patients with neuromyelitis optica is worse than the prognosis in patients with multiple sclerosis.

Causes of Low Vision and Blindness in Adult LatinosThe Los Angeles Latino Eye Study

OBJECTIVE

To describe the causes of low vision and blindness in a population-based sample of adult Latinos.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in Los Angeles, California.

METHODS

Participants underwent a detailed ophthalmologic examination including measurement of best-corrected distance visual acuity using a standard Early Treatment for Diabetic Retinopathy Study protocol, a complete anterior and posterior segment evaluation by an ophthalmologist, Humphrey Visual field testing, and optic disc and fundus photography. Consensus diagnosis of independent investigators reviewing all patient data was used to determine the major causes of low vision and blindness in adult Latinos.

MAIN OUTCOME MEASURES

Primary causes of vision loss in persons with low vision and blindness.

RESULTS

The leading causes of low vision were cataract, diabetic retinopathy, and age-related macular degeneration, together accounting for approximately 82% of all persons with low vision. The primary causes of blindness were age-related macular degeneration, diabetic retinopathy, and myopic degeneration, accounting for 63% of the cases of blindness.

CONCLUSIONS

Many of the leading causes of low vision and blindness in adult Latinos are potentially preventable and treatable diseases. Given the projected aging and growth in the Latino population, consideration needs to be given to the development of targeted early detection and treatment programs.

Perception of blindness and blinding eye conditions in rural communities

PURPOSE

The purpose of this qualitative study was to explore the causes and management of blindness and blinding eye conditions as perceived by rural dwellers of two Yoruba communities in Oyo State, Nigeria.

METHODS

Four focus group discussions were conducted among residents of Iddo and Isale Oyo, two rural Yoruba communities in Oyo State, Nigeria. Participants consisted of sighted, those who were partially or totally blind and community leaders. Ten patent medicine sellers and 12 traditional healers were also interviewed on their perception of the causes and management of blindness in their communities.

FINDINGS

Blindness was perceived as an increasing problem among the communities. Multiple factors were perceived to cause blindness, including germs, onchocerciasis and supernatural forces. Traditional healers believed that blindness could be cured, with many claiming that they had previously cured blindness in the past. However, all agreed that patience was an important requirement for the cure of blindness. The patent medicine sellers' reports were similar to those of the traditional healers. The barriers to use of orthodox medicine were mainly fear, misconception and perceived high costs of care. There was a consensus of opinion among group discussants and informants that there are severe social and economic consequences of blindness, including not been able to see and assess the quality of what the sufferer eats, perpetual sadness, loss of sleep and dependence on other persons for daily activities.

CONCLUSION

Local beliefs associated with causation, symptoms and management of blindness and blinding eye conditions among rural Yoruba communities identified have provided a bridge for understanding local perspectives and basis for implementing appropriate primary eye care programs.

Prevalence of age-related macular degeneration in a population-based sample of Hispanic people in Arizona: Proyecto VER

OBJECTIVE

To report the prevalence of age-related macular degeneration (AMD) in a population-based sample of Hispanic individuals aged 50 years and older.

METHODS

Proyecto VER (Vision and Eye Research) is a population-based study of blindness and visual impairment of Hispanic people in Arizona. Participants underwent complete ophthalmic evaluation, including stereoscopic fundus photography of fields 1, 2, and 4. All photographs for participants aged 50 years and older were graded using the Wisconsin Age-Related Maculopathy Grading system. The following signs were graded: drusen size, drusen type, and the area covered by drusen; pigmentary abnormalities; geographic atrophy; and exudative AMD.

RESULTS

Sixty-seven percent (3178) of the original 4774 participants were 50 years of age or older. Of those, 92% (2928) had fundus photographs in at least 1 eye, and 95% (2780) of the photographs were of sufficient quality to grade early and late AMD.

OUTCOME MEASURES

The overall prevalence of late AMD was 0.5%. The prevalence increased from 0.1% in the 50- to 59-year age group to 4.3% in the group aged 80 years and older. Likewise, early AMD was strongly associated with age with a prevalence of 20% in the 50- to 59-year age group, increasing to 54% in the group aged 80 years and older. The prevalence of early AMD in Hispanic people was significantly higher than the reported prevalence in the white population. However, the prevalence of late AMD was lower than the estimates for the white population of the United States.

CONCLUSIONS

Although early macular changes were very common among Hispanic people, the prevalence of late AMD was infrequent. Further work is necessary to understand the underlying reasons for the different patterns of presentation of early and late signs of AMD among racial/ethnic groups and to characterize early AMD based on predictive value for severe disease in different populations.

[Cataract blindness in people 50 years old or older in a semirural area of northern Peru]

OBJECTIVE

To determine the prevalence of blindness and of cataract blindness in persons 50 years of age or older in Piura and Tumbes, which are two departments in northern Peru, and to describe the coverage and quality of cataract surgery services in that area, and the barriers that prevent access to those services.

METHODS

Systematic sampling of persons 50 years old or older was done in Piura and Tumbes between August 2002 and March 2003, with 80 clusters of 60 people each being selected. Of the 4 800 persons chosen, 4,782 of them were examined, using a survey instrument that gathered general information on each person, the results of the visual acuity test and the lens examination, and information on cataract surgery or why that surgery had not been done. Visual acuity (VA) testing was done with a Snellen optotype with the letter "E," with sizes of 20/60 and 20/200 at distances of 6 m and 3 m, respectively, with the person using the visual correction (glasses) available. When the VA was less than 20/60 in one of the eyes, vision was tested with pinhole glasses.

RESULTS

The prevalence of bilateral blindness (VA < 20/400) due to cataract, adjusted by age and sex, was 2.1% (95% confidence interval (CI): 1.7% to 2.6%). Among the 193 persons with bilateral blindness due to any cause, cataract was the cause in 104 of them (53.9%). The prevalence of blindness due to cataract or other causes increased with age and was higher in women than in men. Only 25% of the persons studied who needed cataract surgery had had that done. The prevalence of bilateral VA less than 20/200 due to unoperated cataract was 6.3% (95% CI: 5.3% to 7.3%); only 12% of the persons with that level of visual deficiency had had cataract surgery. The VA of 26% of the eyes operated on for cataract was lower than 20/200. The reasons given by persons who needed cataract surgery but who had not had it included not being able to pay for the operation (28%), lack of knowledge concerning cataracts (25%), fear of the operation (23%), and fear of completely losing their sight (17%).

CONCLUSIONS

Most of the cases of blindness and of serious deficiency in visual acuity in persons 50 years old or older in Piura and Tumbes are due to uncorrected refractive defects, especially cataracts. The high prevalence of bilateral blindness due to cataracts (2.1%) could be reduced with measures that facilitate access to appropriate treatment.

Exclusion of LCA5 locus in a consanguineous Turkish family with macular coloboma-type LCA

BACKGROUND

Leber's congenital amaurosis (LCA) is an inherited retinal dystrophy, which causes severe visual impairment in early childhood. Recent molecular genetic studies have linked 11 loci (AIPL1, CRB1, CRX, GUCY2D, RPE65, RDH12, RPGRIP1, TULP1, LCA3, LCA5, and LCA9) to LCA. LCA5 is a new locus, which maps to the 6q11-q16 chromosomal region and was found to be associated with macular coloboma-type LCA in a Pakistani family. Herein, we describe the molecular genetic features of a consanguineous Turkish family in which four children have macular coloboma-type LCA.

METHODS

Haplotype analysis was performed on the DNA of the family members using microsatellite markers against GUCY2D, RPE65, and LCA5. Genomic DNA was screened for mutations by means of single-strand conformational polymorphism (SSCP) analysis in exons of the RPE65 and CRX genes.

RESULTS

In haplotype analysis, no linkage to LCA5 or GUCY2D loci was detected. None of the tested markers showed homozygosity or segregation between affected siblings. PCR-SSCP mutation analysis revealed no mutations in the screened RPE65 and CRX genes.

CONCLUSION

We excluded LCA5 as the genetic cause of macular coloboma-type LCA in this Turkish family. Macular coloboma-type LCA shows genetic heterogeneity and it is not possible to establish a phenotype-genotype correlation with LCA5 and macular coloboma.

Access to vision care in an urban low-income multiethnic population

OBJECTIVE

This study applied a well-known, recently revised theoretical model of healthcare access and utilization, the Behavioral Model for Vulnerable Populations, to examine the relationship between access to care and utilization of eye care services among a multiethnic, predominately minority sample of residents from low-income public housing.

DESIGN

Population-based, cross-sectional survey of community sample.

SETTING

Urban Public Housing Communities in Los Angeles County, California.

PARTICIPANTS

A geographically defined stratified random sample of 152 residents (86% Latino or African American) 40 years of age and older from three urban public housing communities.

RESULTS

Only 62% of our sample of persons 40 years and older had received an eye examination within the past 2 years. Sixty-one percent of participants reported having vision care coverage. Yet, one out of four respondents claimed that no health care provider had ever told them that they needed an eye-examination. Applying multiple logistic regression and controlling for a number of predisposing, enabling, and need-for-care characteristics, the variables 1) receiving advice from health care providers for eye examination (OR = 3.9, p < 0.01), 2) possessing coverage for eye-care (OR = 3.2, p < 0.01), and 3) having regular and continuity of medical care (OR = 2.4, p < 0.01) remained significant predictors of eye-examination within the past 2 years.

CONCLUSION

This study documents significantly diminished utilization of eye care services relative to recommended guidelines for a low-income, predominately minority sample of residents from public housing communities. We documented no association between presence of diabetes or hypertension and recency of eye examination. Affordability, continuity, and regular sources of care, as well as receiving physician advice, remain the core factors significantly associated with receiving vision care. These results underscore the need for continued efforts to ensure that the medically underserved minority have access to vision care services. These findings also point toward the urgent need for educational and motivational interventions that encourage health care providers serving underserved communities to promote eye examination, particularly among diabetic patients, hypertensive patients, and other individuals at risk for eye-related disease and complications.

Racial Variations in Causes of Vision Loss in Nursing Homes

OBJECTIVE

To determine the prevalence and causes of low vision in a large sample of nursing home residents.

METHODS

Twenty-eight nursing homes on the Eastern Shore of Maryland and Delaware were enrolled in a clinical trial to assess the impact of vision restoration/rehabilitation on nursing home residents. Visual acuity was measured using both recognition charts and preferential looking techniques. An ophthalmologist examined all residents with visual acuity worse than 20/40 in the better-seeing eye and determined the primary cause for decreased vision. Results are reported for the better-seeing eye.

RESULTS

Of 2544 eligible residents, 1591 (63%) participated, but 286 residents were unable to respond to visual acuity testing. Of the remaining 1307 residents, 496 (37%) had best-corrected visual acuity worse than 20/40 in the better-seeing eye. Causes were ascribed for 412 subjects. Rates of low vision were similar between African American subjects and white subjects (39% and 38%, respectively; age-adjusted P =.18). Cataract was the leading cause of low vision, responsible for 37% of low vision among white subjects and 54% of low vision among African American subjects. Macular degeneration was responsible for 29% of low vision among white subjects but only 7% among African American subjects. Glaucoma caused low vision in 4% of white subjects and 10% of African American subjects. Refractive error was not a frequent cause of low vision in nursing home residents.

CONCLUSIONS

Low vision is highly prevalent among nursing home residents, with 37% having visual acuity worse than 20/40 in the better-seeing eye. Differences in causes of low vision between African American subjects and white subjects were noted, with African American subjects more likely to have vision loss on the basis of cataract, a readily treated condition. Appropriate interventions for nursing home residents, who face significant obstacles in accessing eye care services, have the potential to improve the quality of life of this at-risk older population.

Prevalence and risk indicators of visual impairment and blindness in Latinos: the Los Angeles Latino Eye Study

OBJECTIVE

To determine the age- and gender-specific prevalence and risk indicators of visual impairment and blindness in urban Latinos 40 years and older.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in Los Angeles, California.

METHODS

Of the 6357 study participants, 6122 underwent a complete ophthalmologic examination at the clinical center, including measurement of best-corrected distance visual acuity (VA) using a standard Early Treatment Diabetic Retinopathy Study protocol. Age- and gender-specific prevalence of visual impairment and blindness were contrasted using Mantel-Haenszel procedures. Sociodemographic and clinical risk indicators of visual impairment were explored using stepwise logistic regression.

MAIN OUTCOME MEASURES

Prevalence and odds ratios for risk indicators of visual impairment and blindness.

RESULTS

The overall prevalence for visual impairment (best-corrected VA of <==20/40 in the better eye) was 3.0% (n = 182) (range, 0.9% [40-49 years]-27.8% [>/=80 years]). The overall prevalence for blindness (best-corrected VA of <==20/200 in the better eye) was 0.4% (n = 26) (range, 0.2% [40-49 years]-4.2% [>/=80 years]). Visual impairment increased with age (P<0.0001) and was greater in women (P = 0.02). Independent risk indicators (odds ratio [95% confidence interval]) for visual impairment were age 70-79 years (2.8 [1.3-5.8]) or >/=80 years (8.7 [3.9-19.6]), history of ocular disease (3.2 [2.1-4.8]), being unemployed (3.3 [1.7-6.3]), diabetes (2.2 [1.5-3.2]), and being separated/divorced (1.8 [1.0-3.1]) or widowed (2.8 [1.8-4.4]). Participants with >/=12 years of education (0.5 [0.3-0.8]) were less likely to be visually impaired.

CONCLUSIONS

Rates of visual impairment and blindness in Latinos are high, especially in older individuals. Better education and employment are likely to decrease the burden of visual impairment in Latinos.

The Los Angeles Latino Eye Study: design, methods, and baseline data

OBJECTIVE

To describe the study design, operational strategies, procedures, and baseline characteristics of the Los Angeles Latino Eye Study (LALES), a population-based assessment of the prevalence of visual impairment, ocular disease, and visual functioning in Latinos.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in Los Angeles, California.

METHODS

A detailed interview and eye examination were performed on each eligible participant. The interview included an assessment of demographic, behavioral, and ocular risk factors and health-related and vision-related quality of life. The eye examination included a measurement of visual acuity, intraocular pressure, and visual fields; fundus and optic disc photography; a detailed anterior and posterior segment examination; and measurement of blood pressure, glycosylated hemoglobin levels, and blood glucose levels.

MAIN OUTCOME MEASURES

Prevalence of visual impairment, blindness, cataract, glaucoma, diabetic retinopathy, and age-related macular degeneration constitute the study's primary outcome variables. Secondary outcomes include odds ratios for risk factors associated with eye disease, health-related quality of life, and vision-related quality of life. Response rates and baseline characteristics are presented.

RESULTS

Of the 7789 individuals eligible for LALES, 6357 (82%) had a clinical examination; an additional 524 completed only an in-home interview. The majority of participants were female (58%), the average (+/- standard deviation) age was 54.9 (+/-10.8) years, and 80.0% were of Mexican origin and 0.4% self-identified as American Indian or Alaskan Native. The age distribution of LALES participants was similar to that of Latinos of Mexican origin in the rest of the United States.

CONCLUSION

The LALES has recruited Latinos 40 and older for an ophthalmic epidemiologic study. The LALES cohort will provide information about the prevalence and risk factors of ocular disease in the largest and fastest growing minority in the United States.

Attitudes towards and perceptions of visual loss and its causes among Hong Kong Chinese adults

BACKGROUND

As part of a study of visual function among Hong Kong Chinese adults, their attitudes and perceptions related to visual loss were examined. These included fear of visual loss, negative functional impacts of visual loss, the relationship between ageing and visual loss and help-seeking behaviours related to visual loss. Demographic factors associated with these variables were also studied.

METHODS

The study population were people aged 40 and above randomly selected from the Shatin district of Hong Kong. The participants underwent eye examinations that included visual acuity, intraocular pressure measurement, visual field, slit-lamp biomicroscopy and ophthalmoscopy. The primary cause of visual disability was recorded. The participants were also asked about their attitudes and perceptions regarding visual loss using a structured questionnaire.

RESULTS

The prevalence of bilateral visual disability was 2.2% among adults aged 40 or above and 6.4% among adults aged 60 or above. Nearly 36% of the participants selected blindness as the most feared disabling medical condition, which was substantially higher than conditions such as dementia, loss of limbs, deafness or aphasia. Inability to take care of oneself (21.0%), inconvenience related to mobility (20.2%) and inability to work (14.8%) were the three most commonly mentioned 'worst impact' effects of visual loss. Fully 68% of the participants believed that loss of vision is related to ageing. A majority of participants would seek help and advice from family members in case of visual loss.

CONCLUSIONS

Visual function is perceived to be very important by Hong Kong Chinese adults. The fear of visual loss is widespread and particularly affects self-care and functional abilities. Visual loss is commonly seen as related to ageing. Attitudes and perceptions in this population may be modified by educational and outreach efforts in order to take advantage of preventive measures.

Causes and Prevalence of Visual Impairment Among Adults in the UnitedStates

OBJECTIVES

To estimate the cause-specific prevalence and distribution of blindness and low vision in the United States by age, race/ethnicity, and gender, and to estimate the change in these prevalence figures over the next 20 years.

METHODS

Summary prevalence estimates of blindness (both according to the US definition of < or =6/60 [< or =20/200] best-corrected visual acuity in the better-seeing eye and the World Health Organization standard of < 6/120 [< 20/400]) and low vision (< 6/12 [< 20/40] best-corrected vision in the better-seeing eye) were prepared separately for black, Hispanic, and white persons in 5-year age intervals starting at 40 years. The estimated prevalences were based on recent population-based studies in the United States, Australia, and Europe. These estimates were applied to 2000 US Census data, and to projected US population figures for 2020, to estimate the number of Americans with visual impairment. Cause-specific prevalences of blindness and low vision were also estimated for the different racial/ethnic groups.

RESULTS

Based on demographics from the 2000 US Census, an estimated 937 000 (0.78%) Americans older than 40 years were blind (US definition). An additional 2.4 million Americans (1.98%) had low vision. The leading cause of blindness among white persons was age-related macular degeneration (54.4% of the cases), while among black persons, cataract and glaucoma accounted for more than 60% of blindness. Cataract was the leading cause of low vision, responsible for approximately 50% of bilateral vision worse than 6/12 (20/40) among white, black, and Hispanic persons. The number of blind persons in the US is projected to increase by 70% to 1.6 million by 2020, with a similar rise projected for low vision.

CONCLUSIONS

Blindness or low vision affects approximately 1 in 28 Americans older than 40 years. The specific causes of visual impairment, and especially blindness, vary greatly by race/ethnicity. The prevalence of visual disabilities will increase markedly during the next 20 years, owing largely to the aging of the US population.

Impact of age and duration on sight–threatening retinopathy in South Asians and Caucasians attending a diabetic clinic

AIMS

To examine diabetic retinopathy in Asians and Caucasians attending a hospital diabetic clinic and to evaluate the impact of the significant risk factors on the probability of sight-threatening retinopathy.

METHODS

A total of 500 diabetic patients (268 Asians, 232 Caucasians) who attended a diabetic clinic within a defined time period were examined for severity of diabetic retinopathy. The existence of sight-threatening retinopathy (STR) was compared in the two groups. Significant risk factors such as age, duration and hypertension were analysed against the probability of STR in each of the two races.

RESULTS

Asians demonstrated significantly higher rates of STR. Univariate analysis showed age, duration, race, gender, and insulin-requiring status to be significantly associated with STR. Multivariate logistic regression showed a significant association of STR with race, age and duration of diabetes, with no significant interaction effects between variables. The logistic regression model predicted STR in Asians to be matched to that in Caucasians by a 12.5-year difference factor; that is, Caucasians were older by 12.5 years or had a 12.5-year longer duration than Asians for the same level of STR.

CONCLUSIONS

After adjusting for age and duration of diabetes, the probability of STR in Asian diabetic patients attending the diabetic clinics in Bradford is significantly higher than that in Caucasians (odds ratio=3.184, P<0.05). The impact of age and duration was significantly higher in patients of South Asian origin compared to Caucasians.

Prevalence and causes of visual impairment in an elderly Chinese population in Taiwan: the Shihpai Eye Study

OBJECTIVE

Few population-based data on the prevalence and causes of visual impairment are available from East Asia. The purpose of this study was to determine the prevalence and causes of visual impairment in an elderly Chinese population in Taiwan.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

The Shihpai Eye Study was a survey of vision and ocular disease among an elderly Chinese population 65 years of age or older residing in Shihpai, Taiwan. A random sample of 2045 elderly residents was identified and selected from the household registration databank. Among them, 1361 (66.6%) underwent a detailed ophthalmic examination.

METHODS

The ophthalmic examination included best-corrected visual acuity measurements using standardized protocols. Visual acuity was assessed with a Snellen E chart. The major cause of visual loss was identified for all participants who were visually impaired.

MAIN OUTCOME MEASURES

Low vision and blindness were defined as a best-corrected visual acuity in the eye with better vision worse than 20/60 to a lower limit of 20/400 and worse than 20/400, respectively, according to World Health Organization categories of visual impairment.

RESULTS

The mean age of the participants was 72.2 (range, 65-91) years old. A total of 40 participants met the World Health Organization criteria of low vision, and 8 were diagnosed as blind. The rate of blindness and low vision was estimated to be 0.59% (95% confidence interval, 0.25%, 1.16%) and 2.94% (95% confidence interval, 2.11%, 3.99%), respectively. There was a significant increase in the rate of low vision (P<0.001) from 0.83% at 65 to 69 years of age to 8.33% at age 80 years or older. There was no gender difference in the prevalence of blindness or low vision. The leading cause of visual impairment was cataract (41.7%), followed by myopic macular degeneration (12.5%) and age-related macular degeneration (10.4%).

CONCLUSIONS

The rate of blindness and low vision is close to that reported for other developed countries. The high frequency of myopic macular degeneration as a major cause of visual loss, however, is not observed in European-derived populations. Specific prevention or low-vision rehabilitation programs should be developed for the elderly Chinese population.

Four-year incidence of visual impairment: Barbados Incidence Study of Eye Diseases

OBJECTIVE

To describe the 4-year incidence of visual impairment and causes of blindness among black participants of the Barbados Eye Studies.

DESIGN

Population-based incidence study.

SETTING AND PARTICIPANTS

The Barbados Incidence Study of Eye Diseases (BISED) followed the cohort of the Barbados Eye Study (BES), a prevalence study based on a simple random sample of Barbadians 40 to 84 years of age. BISED included 3193 black participants from the original cohort (85% of those eligible).

MAIN OUTCOME MEASURES

Best-corrected visual acuity (Ferris-Bailey chart) at baseline and follow-up was measured according to a modified Early Treatment of Diabetic Retinopathy Study protocol. By use of World Health Organization (WHO) criteria, low vision and blindness for an individual were defined as visual acuity (VA) <6/18 to 6/120 and <6/120, respectively, in the better eye. By commonly used US criteria, low vision and blindness were defined as VA < or = 20/40 and < or = 20/200, respectively. Vision loss was defined as a doubling of the visual angle (i.e., decrease of 15 letters or more read correctly between baseline and follow-up examinations). Progression was defined as vision loss among those with low vision at baseline.

RESULTS

On the basis of WHO criteria, the overall 4-year incidence was 3.6% (95% confidence interval [CI], 3.0%-4.4%) for low vision and 0.6% (95% CI, 0.4%-1.0%) for blindness. Incidence rates were higher using US criteria: 5.3% (95 % CI, 4.5%-6.2%) and 1.5% (95% CI, 1.1%-2.0%), respectively, reaching 21.5% and 7.3% for persons aged 70 years or older at baseline. One tenth of the cohort had vision loss, and 28.6% of those with low vision progressed. About one half of incident blindness was due to age-related cataract. Nearly one fifth was caused by open-angle glaucoma (OAG) alone or combined with cataract, and approximately 10% was caused by diabetic retinopathy (DR).

CONCLUSIONS

The incidence of visual impairment was high in this Afro-Caribbean population, particularly in older age groups, indicating the public health significance of visual loss for this and similar black populations. Cataract, OAG, and DR were among the leading causes of incident blindness, paralleling their high prevalence in this population.

Novel mutation in FOXC1 wing region causing Axenfeld-Rieger anomaly

PURPOSE

To determine the possible molecular genetic defect underlying Axenfeld-Rieger anomaly (ARA) and to identify the pathogenic mutation causing this anterior segment dysgenesis in an Indian pedigree.

METHODS

The FOXC1 gene was amplified from genomic DNA of members of an ARA-affected family and control subjects using four novel sets of primers. The amplicons were directly sequenced, and the sequences were analyzed to identify the disease-causing mutation.

RESULTS

A heterozygous novel missense mutation was identified in the coding region of the FOXC1 gene in all three patients in this family. Consistent with the autosomal dominant inheritance pattern, the mutation segregated with the disease phenotype and was fully penetrant. The mutation was found in the wing region of the highly conserved forkhead domain of the FOXC1 gene and resulted in a very severe phenotype leading to blindness.

CONCLUSIONS

This is the first study to demonstrate that a mutation in the FOXC1 wing region can cause an anterior segment dysgenesis of the eye. This mutation resulted in blindness in the ARA-affected family, and the findings suggest that the FOXC1 wing region has a functional role in the normal development of the eye. Moreover, this is the first study from India to report the genetic etiology of Axenfeld-Rieger anomaly. Genotype-phenotype correlations of FOXC1 may help in establishing the disease prognosis and also in understanding the clinical and genetic heterogeneity associated with various anterior segment dysgenesis caused by this gene.

The clinical characteristics of Asian and Caucasian patients on Bradford's Low Vision Register

AIM

To analyse the clinical characteristics of patients on the Bradford Low Vision Register with regards to the type (partially sighted or blind), sex, race, causes and age at registration.

METHODS

All the data were obtained from the Morley Street Resource Centre, which keeps records of all registrations in the Bradford Metropolitan District. Information including postcode, date of birth, age, gender, ethnic group, degree, date of registration, cause of registration and age at registration were entered into a database.

RESULTS

Of all registrations, 64% were blind and 36% were partially sighted. Asians were younger at registration and there were a significantly lower number of females compared to Caucasians. When data were analysed for the different age groups, in the older group of over 65 years, Asians showed significantly more diabetic retinopathy (26.1%) compared to Asians (7.8%), while Caucasians demonstrated significantly more glaucoma (C: 29.3%; A: 17.4%). In the younger age group (<30 years), the leading causes for Asians were retinitis pigmentosa and nystagmus while for Caucasians it was congenital cataracts and optic atrophy. The proportion of Asians registered was significantly lower than expected from the projected population estimates in Bradford.

CONCLUSIONS

The study indicates significant differences in the clinical profiles of the two racial groups. The data do not follow the predictions from published population estimates, with Asians, especially females, being under-represented in the register.

Learning to live with glaucoma: a qualitative study of diagnosis and the impact of sight loss

Glaucoma is a major cause of preventable sight loss. As there are no obvious symptoms in the early stages, when it is most beneficial to start treatment, the key to reducing undiagnosed glaucoma in the community is better case finding among those at higher risk. This qualitative study aimed to identify triggers to self-referral for glaucoma symptoms in a sample from Britain, and to explore the meaning of symptoms for people living with moderate to severe glaucoma. Participants (N = 28) reported low levels of awareness of glaucoma prior to their diagnosis, and had assumed that symptoms were the 'normal' deterioration of eyesight expected with other morbidity or advancing age. As symptoms have a gradual onset, participants had learnt to cope with diminishing sight ability. However, many reported that such coping was 'at a cost', and that managing in a world designed for the well sighted caused problems for activities of everyday living, work and family life. The salience of these problems was shaped primarily by social factors, which framed both the practical consequences of sight loss and their meaning for respondents. Findings from this study suggest health promotion is a priority to increase public awareness of the existence and symptoms of glaucoma among those at high risk, and that more attention could be given to reducing the environmental and social causes of disability.

Causes of blindness and visual impairment in a population-based sample of U.S. Hispanics

OBJECTIVE

To describe the causes of blindness and visual impairment in a population-based sample of Hispanics.

DESIGN

A cross-sectional study.

PARTICIPANTS

A random sample of 4774 Hispanic residents of Santa Cruz and Pima Counties in Southern Arizona aged 40 years and older who participated in Proyecto VER (Vision Evaluation and Research).

TESTING

Subjects were interviewed and underwent a thorough ophthalmic examination. Presenting and best-corrected visual acuity was determined using the Early Treatment of Diabetic Retinopathy Study protocol, followed by a standardized ophthalmic examination to determine the causes of visual loss. Anterior and posterior segment specialists in ophthalmology confirmed the causes.

MAIN OUTCOME MEASURES

Causes of visual loss (best-corrected acuity worse than 20/40).

RESULTS

The response rate of eligible participants was more than 70%. Best-corrected acuity in the better seeing eye worse than 20/40 increased from 0.3% in those aged 40 to 49 to 5.6% in those aged 65 and older. The leading cause was cataract, accounting for 42% of all visual loss, followed by age-related macular degeneration (15%), and diabetic retinopathy (13%). Among 14 people who were bilaterally blind, open-angle glaucoma was the leading cause. Women had higher age-adjusted prevalence of severe cataract compared with men and were more likely to be visually impaired from cataract, diabetic retinopathy, and open-angle glaucoma, although gender differences were not statistically significant.

CONCLUSIONS

Causes of visual impairment differ from those reported in Caucasian populations, with open-angle glaucoma being the leading cause of blindness. Further work on gender-based obstacles to eye care in the Hispanic community may be warranted.

Blindness, visual impairment and the problem of uncorrected refractive error in a Mexican-American population: Proyecto VER

PURPOSE

To report the prevalence of blindness and visual impairment and the contribution of uncorrected refractive error to visual loss, in a population-based sample of Mexican Americans aged 40 and older.

METHODS

Proyecto VER is a population-based study of blindness and visual impairment in Mexican Americans in Arizona. Block groups in Tucson and Nogales were randomly selected with probability proportional to the size of the Mexican-American population aged 40 and older. Participants had a complete ophthalmic evaluation, including assessment of presenting and best corrected visual acuity using standardized procedures. Those with presenting visual acuity worse than 20/30 had refraction to determine best corrected vision. A home questionnaire and a clinic examination provided data on education, perception of visual impairment, income, and acculturation.

RESULTS

The prevalence of presenting visual acuity worse than 20/40 was 8.2%, with uncorrected refractive error accounting for 73% of the impaired acuity. In multivariate models comparing those who improved two or more lines on the acuity chart with proper refraction with those who had adequate optical correction, uncorrected refractive error showed a strong association with age, less than 13 years of education (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.5-2.0), low acculturation index (OR 1.3, CI 1.1-1.3), lack of insurance coverage (OR 1.4, CI 1.1-1.7), and not having seen an eye-care provider in the past 2 years (OR 2.5, CI 2.1-3.0). Prevalence of best corrected acuity worse than 20/40 increased from 0.3% in those aged 40 to 49 years to 18% in those aged 80 years or more.

CONCLUSIONS

Visual loss in this Mexican-American population is higher than has been reported in whites and is comparable to that in African Americans. Almost three quarters of those with visual acuity impairment would improve with optical correction. Socioeconomic factors that are probable markers of limited access to health care services were associated with uncorrected refractive error. These data suggest that education programs and interventions to improve access to eye care could significantly decrease the burden of visual loss among Mexican Americans.

Prevalence and causes of visual impairment in The Barbados Eye Study

OBJECTIVE

To determine the prevalence and causes of low vision and blindness in a predominantly black population.

DESIGN

Population-based prevalence study of a simple random sample of Barbados-born citizens aged 40 to 84 years.

PARTICIPANTS

Four thousand seven hundred nine persons (84% participation).

METHODS

The standardized protocol included best-corrected visual acuity (with a Ferris-Bailey chart), automated perimetry, lens gradings (LOCS II), and an interview. Participants with visual acuity of worse than 20/30, other positive findings, and a 10% sample also had an ophthalmologic examination that evaluated the cause and extent of vision loss (resulting from that cause), if any.

MAIN OUTCOME MEASURES

Low vision and blindness were defined as visual acuity in the better eye between 6/18 and 6/120 and visual acuity worse than 6/120, respectively (World Health Organization [WHO] criteria).

RESULTS

Of the 4631 participants with complete examinations, 4314 (93%) reported their race as black, 184 (4%) reported their race as mixed (black and white), and 133 (3%) reported their race as white or other. Low vision was found in 5.9% of the black, 2.7% of the mixed, and 3.0% of white or other participants. Bilateral blindness was similar for black and mixed race participants (1.7% and 1.6%, respectively) and was not found in whites. Among black and mixed participants, the prevalence of low vision increased with age (from 0.3% at 40-49 years to 26.8% at 80 years or older). The prevalence of blindness was higher (P < 0.001) for men than women at each age group (0.5% versus 0.3% at ages 40-49 and 10.9% versus 7.3% at 80 years or more). Sixty percent of blindness was due to open-angle glaucoma and age-related cataract, each accounting for more than one fourth of cases. Other major causes were optic atrophy or neuropathy and macular and other retinal diseases. Few cases of blindness were due to diabetic retinopathy (1.4%), and none were due to age-related macular degeneration.

CONCLUSIONS

Using the WHO criteria, prevalence of visual impairment was high in this African-origin population, particularly at older ages. Most blindness was due to open-angle glaucoma and cataract, with open-angle glaucoma causing a higher proportion of blindness than previously reported. The increased prevalence of blindness in men may be due to the increased male prevalence of glaucoma in this population and warrants further investigation. Results underline the need for blindness prevention programs, with emphasis on effective treatment of age-related cataract and enhancing strategies for early detection and treatment of open-angle glaucoma.

Leber's congenital amaurosis with anterior keratoconus in Pakistani families is caused by the Trp278X mutation in the AIPL1 gene on 17p

BACKGROUND

Leber's congenital amaurosis (LCA) represents the earliest and severest form of retinal dystrophy leading to congenital blindness. A total of 20% of children attending blind schools have this disease. LCA has a multigenic basis and is proving central to our understanding of the development of the retina. We describe the clinical and molecular genetic features of four inbred pedigrees from neighbouring remote villages in northern Pakistan, in which some of the affected members have concurrent keratoconus.

METHODS

History-taking and physical and eye examinations were performed in the field. Venipuncture, DNA extraction, studies of linkage to known LCA genes, automated sequencing and polymorphism analyses for haplotype assessments were done.

RESULTS

We examined 12 affected and 15 unaffected family members. By history, there were an additional nine blind people in the four pedigrees. In each pedigree a consanguineous marriage was evident. We found a homozygous nonsense mutation in the AIPL1 gene, which replaces a tryptophan with a stop codon (Trp278X). The phenotype is severe and variable, despite the common molecular genetic etiology in each family. Affected patients had hand motion to no light perception vision and fundus findings ranging from maculopathy to diffuse pigmentary retinopathy. Three affected members had definite keratoconus, and two were suspects based on mild cone formation in the cornea of at least one eye.

INTERPRETATION

We have identified four Pakistani families with a severe form of LCA that is associated with severe keratoconus in some affected members. The molecular etiology in all four families is a homozygous nonsense mutation, Trp278X, in the photoreceptor-pineal gene AIPL1. To our knowledge, this is one of the first phenotype-genotype correlations of AIPL1-associated LCA.

Screening for CRX gene mutations in Chinese patients with Leber congenital amaurosis and mutational phenotype

PURPOSE

To screen for possible disease-causing mutations in the CRX gene in Chinese patients with Leber congenital amaurosis (LCA) and to enrich the understanding of its mutational phenotype.

METHODS

Genomic DNA was collected from 27 patients with LCA. The coding sequences of the CRX gene were analyzed using the PCR-heteroduplex-SSCP method. Mutations were confirmed by DNA sequencing.

RESULTS

We identified two heterozygous variations in the CRX gene in two patients with LCA. One was a deletion (GCC-->-CC, A181D1bp) leading to a frameshift and protein truncation. This mutation was present in a patient with LCA, but not in his healthy parents. The ocular manifestations of this A181Delta1bp mutation are described. An intronic variation (IVS1-13G-->C) was found in a patient with LCA as well as in his healthy father.

CONCLUSION

A heterozygous A181D1bp mutation in the CRX gene caused an LCA phenotype in a Chinese patient.

The prevalence of glaucoma in Chinese residents of Singapore: a cross-sectional population survey of the Tanjong Pagar district

BACKGROUND

Data on prevalence of glaucoma in East Asia are scarce.

OBJECTIVE

To determine the prevalence and clinical characteristics of glaucoma in adult Chinese Singaporeans.

METHODS

A group of 2000 Chinese people, aged 40 to 79 years, were selected from the electoral register of Tanjong Pagar district in Singapore using a disproportionate, stratified, clustered, random-sampling procedure. Glaucoma was diagnosed in people with an excavated optic neuropathy and a reproducible visual field defect or on the basis of severe structural disc abnormality alone, if reliable field results could not be obtained. The diagnosis was also made in blind subjects with raised intraocular pressure or previous glaucoma surgery.

RESULTS

Of 1717 eligible subjects, 1232 were examined, with a response rate of 71.8%. There were 45 cases of glaucoma: 27 were men and 18 were women. The main diagnoses were primary open-angle glaucoma (n = 22 [49%]), primary angle-closure glaucoma (n = 14 [31%]), and secondary glaucoma (n = 7 [16%]). It was not possible to determine the mechanism in 2 (4%).

CONCLUSIONS

The age-standardized prevalence of glaucoma was 3.2% (95% confidence interval, 2.3-4.1) in the population 40 years and older. Glaucoma was the leading cause of blindness. Primary angle-closure glaucoma and secondary glaucoma were the most visually destructive forms of the disease. Our findings suggest current projections of glaucoma prevalence among ethnic Chinese are a substantial underestimate. Arch Ophthalmol. 2000;118:1105-1111

Causes of blindness and visual impairment in a population of older Americans: The Salisbury Eye Evaluation Study

OBJECTIVE

To determine the causes of blindness and visual impairment in a population-based sample of older Americans.

METHODS

A random sample of 3821 residents of Salisbury, Md, between the ages of 65 and 84 years was identified from Medicare records. Sixty-six percent (2520 persons) agreed to undergo an eye examination; 26% of the participants were African American. The clinical examination included acuity testing with an Early Treatment Diabetic Retinopathy Study chart and standardized refraction testing for those with a visual acuity worse than 20/30, slitlamp and dilated retinal examination by an ophthalmologist, tonometry, lens and fundus photography, and a suprathreshold visual field test. Visual impairment was defined as a best-corrected acuity in the better-seeing eye worse than 20/40 and better than 20/200, while blindness was acuity in the better-seeing eye of 20/200 or worse. For those with a visual acuity worse than 20/40 in either eye, one or more causes were assigned by an ophthalmologist and a final cause for each eye was confirmed by a panel of 3 subspecialty ophthalmologists (O.D.S., H.A.Q., and S.B.B.) based on all available evidence.

RESULTS

Bilateral presenting acuity worse than 20/40 increased from 4% in the 65- to 74-year age group to 16% in the 80- to 84-year age group. One third of those with presenting acuity worse than 20/40 improved to 20/40 or better with refraction. Overall, 4.5% had a best-corrected acuity worse than 20/40. African Americans were more likely to remain visually impaired than were whites despite refraction (odds ratio [95% confidence interval], 1.7 [1.1-2.6]). Whites were most often impaired or blind from age-related macular degeneration (1.2% vs 0.5%; P=.09). African Americans had higher rates of impairment and blindness from cataract or posterior capsular opacification (2.7% vs 1.1%; P=.006), glaucoma (0.9% vs 0.1%; P=.006), and diabetic retinopathy (1.2% vs 0.2%; P=. 004).

CONCLUSIONS

More than half of those with visual impairment or blindness had conditions that were either surgically treatable or potentially preventable. African Americans had a disproportionate number of blinding diseases, particularly those amenable to eye care intervention. Targeted interventions for specific populations to increase appropriate eye care use would greatly improve vision and function in older Americans. Arch Ophthalmol. 2000;118:819-825

Sorsby's fundus dystrophy in two Japanese families with unusual clinical features

PURPOSE

To describe two Japanese families with Sorsby's fundus dystrophy (SFD) with unusual clinical features.

METHODS

Two families from Kagoshima Prefecture with senile-onset macular dystrophy were examined. Three affected individuals through three successive generations of one family and three affected siblings in another family were examined and followed.

RESULTS

The initial symptom of these patients was a rapid or slow central visual loss that occurred at an average age of 67.4 years. The major ophthalmoscopic changes consisted of soft drusen and hemorrhagic or atrophic lesions in the macula, which were progressive and ultimately led to disciform scarring. They had no difficulty with night vision. All the patients had normal peripheral retina with intact peripheral fields. They maintained good ambulatory vision and could walk unguided until late in life. These patients had a novel mutation in the tissue inhibitor of the metalloproteinases-3 (TIMP3) gene.

CONCLUSIONS

This is the first report of SFD from the East. Its clinical features differ from those of SFD patients of the West, appearing closer to features of age-related macular degeneration. These two unrelated Japanese families with an identical mutation in the TIMP3 gene might be descendants of a common ancestor who carried the mutant gene.

The causes of childhood blindness in South Africa

OBJECTIVES

1. To ascertain the causes of severe visual impairment and blindness in children in schools for the blind in South Africa. 2. To determine the major avoidable causes. 3. To determine causation by ethnic group.

DESIGN

A cross-sectional survey, undertaken at 15 of the 16 schools for the blind in South Africa, during May-September 1996, using standard WHO methodology.

SUBJECTS

Children less than 16 years of age on May 1996.

RESULTS

Of 1,615 eligible children, 1,311 were examined. According to WHO categories of visual impairment, using the corrected visual acuity in the better eye, 30.4% of children were blind (< 3/60, BL), 12.6% had severe visual impairment (< 6/60-3/60, SVI), 42.3% were visually impaired (< 6/18-6/60), and 12.0% had no impairment (6/18 or better). The anatomical sites of SVI/BL in 564 children were: retina 38.5%; optic nerve 15.2%; cornea/phthisis bulbi 11.0% and glaucoma 6.7%. Aetiological categories of SVI/BL were: hereditary diseases 33.0%; intra-uterine factors 0.9%; perinatal conditions 13.1%; acquired conditions of childhood 11.5%. In 41.5% the underlying cause could not be determined. In 38.8% of children with SVI/BL the cause was avoidable, i.e. preventable or treatable. The main causes varied between ethnic groups, the major difference being the higher proportion of retinopathy of prematurity in white and Indian children.

CONCLUSIONS

The study suggests that 38.8% of causes of SVI or blindness in children in schools for the blind in South Africa are avoidable, and that specific control measures need to be targeted at different ethnic groups.