Suh-Yuh Wu

Patterns of adherence to diabetes vision care guidelines: Baseline findings from the Diabetic Retinopathy Awareness Program☆

OBJECTIVES (1) To describe baseline patterns of adherence to American Diabetes Association and American Academy of Ophthalmology vision care guidelines for diabetes in the Diabetic Retinopathy Awareness Program, and (2) to evaluate factors associated with nonadherence. This paper describes the baseline characteristics of a population enrolled in a prospective, randomized clinical trial. DESIGN Cross-sectional study. PARTICIPANTS Between October 1993 and May 1994, the study identified 2308 persons with diabetes, 18 years of age or older, who were residents of Suffolk County, New York, via a multimedia community-wide recruitment campaign. INTERVENTION AND METHODS Eligibility for the trial was determined during a 20-minute phone interview, which included questions about vision care practices; diabetes management; and knowledge, attitudes, and beliefs about diabetes, vision, and diabetic retinopathy. This paper describes these patient characteristics at baseline. Eligible patients would be randomized subsequently to a 2-year diabetes educational intervention arm, which included mailed packets and newsletters focused on vision care, or to a control nonintervention arm. MAIN OUTCOME MEASURE Nonadherence to guidelines at baseline was defined as the absence of a dilated eye examination during the year before recruitment into the study. RESULTS Of the 2308 persons interviewed, 813 (35%) did not follow the vision care guidelines; two thirds of this group reported no eye examination in the year before the interview, and one third had an undilated examination. Ophthalmologists performed 49% of the examinations in the nonadherent group, versus 86% in the adherent group. In logistic regression analyses, factors related to nonadherence were: younger age (odds ratio [OR] = 0.97), type 2 diabetes with or without insulin use (OR = 1.62 and 1.99, respectively), shorter diabetes duration (OR = 0.97), last eye examination performed by an optometrist (OR = 5.32) or other nonophthalmologist (OR = 4.29), less practical knowledge about diabetes (OR = 1.57), and no prior formal diabetes education (OR = 1.30). CONCLUSIONS Within this population, more than one third of participants had not been following vision care guidelines. Nonadherence was linked to several potentially modifiable factors; changes in these factors could enhance the early detection of diabetic retinopathy.

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.

Antioxidant vitamins and nuclear opacities: the longitudinal study of cataract.

OBJECTIVE The association of antioxidant nutrients and risk of nuclear opacification was evaluated in the Longitudinal Study of Cataract. DESIGN Nutritional data were collected at baseline on the 764 participants, which included assessment of dietary intake, use of vitamin supplements, and plasma levels of vitamin E. Ophthalmologic and other data were collected at baseline and at yearly follow-up visits, including lens photographs, which were graded using the Lens Opacities Classification System III protocol. MAIN OUTCOME MEASURES Analyses examined whether the nutritional factors at baseline were related to increases in nuclear opacification at follow-up. The MULCOX2 approach, an extension of the Cox regression model, was used. Results are presented as relative risks (RRs) and 95% confidence intervals. INTERVENTION Intervention was not applicable. RESULTS The risk of nuclear opacification at follow-up was decreased in regular users of multivitamin supplements (RR = 0.69; 0.48-0.99), vitamin E supplements (RR = 0.43; 0.19-0.99), and in persons with higher plasma levels of vitamin E (RR = 0.58; 0.36-0.94). CONCLUSIONS In regular users of multivitamin supplements, the risk of nuclear opacification was reduced by one third; in regular users of vitamin E supplements and persons with higher plasma levels of vitamin E, the risk was reduced by approximately half. These results are similar to those obtained in our earlier case-control study. Because these data are based on observational studies only, the results are suggestive but inconclusive. The possible effect of nutritional supplements on the lens requires confirmation by ongoing clinical trials.

Hypertension, diabetes, and longitudinal changes in intraocular pressure

PURPOSE Diabetes and hypertension are recognized risk factors for raised intraocular pressure (IOP). This report examines the longitudinal relationship of hypertension and diabetes to a 4-year IOP change in a black population with high prevalence of these conditions. DESIGN Population-based cohort study of a simple random sample of residents of Barbados, West Indies, aged >/=40 years. PARTICIPANTS A total of 2996 persons without open-angle glaucoma or receiving IOP-lowering medication at baseline. METHODS Participants underwent standardized examinations including applanation tonometry, measurement of blood pressure, and anthropometric indices; a detailed interview; various ocular measurements; and venipuncture for glycosylated hemoglobin (GHb). Diabetes was defined by self-reported physician diagnosis and hypertension by blood pressure >/=140/90 mmHg and/or treatment history. MAIN OUTCOME MEASURES The 4-year person-based IOP change between baseline and follow-up was defined as the more positive IOP difference in either eye. RESULTS An IOP >21 mmHg at baseline was more likely in black and in mixed (black and white) participants (age-gender adjusted odds ratio [OR], 3.9 and 3.8, respectively) than in whites. Similarly, these groups had more hypertension (age-gender adjusted OR, 2.4 and 2.1, respectively) and diabetes (age-gender adjusted OR, 3.9 and 1.7, respectively) than did whites. Mean IOP in black participants increased by 2.5 (standard deviation, 3.9) mmHg over 4 years. Multiple regression analyses showed that baseline diabetes history and hypertension, as well as older age, elevated GHb, higher blood pressures, and lower baseline IOP were associated with a 4-year increase of IOP. The association between diabetes history/GHb and IOP increase became borderline/nonsignificant when persons who underwent cataract surgery during follow-up were excluded. CONCLUSIONS This report provides new data on the relationship of systemic factors to longitudinal increases in IOP in an African-origin population. Results highlight the increased risk of elevated IOP in populations with high prevalences of diabetes and hypertension.

Risk factors for incident nuclear opacities

PURPOSE To evaluate risk factors for the 4-year incidence of nuclear opacities. DESIGN Population-based cohort study (85% participation at 4-year follow-up). PARTICIPANTS Two thousand six hundred nine black participants of the Barbados Eye Studies, without any nuclear opacities at baseline. METHODS Participants completed a standardized protocol at baseline and follow-up, including ophthalmic and other measurements, an interview, slit-lamp lens grading, fundus photography, and an ophthalmologic examination. Factors associated with the incidence of nuclear opacities (Lens Opacities Classification System II N > or = 2) were evaluated by logistic regression. MAIN OUTCOME MEASURE Relative risks (RR) with 95% confidence intervals (95% CI). RESULTS The 4-year incidence of nuclear opacities was 9.2% (241 of 2609) and increased greatly with age. Women were at significantly greater risk (RR = 1.8), as were persons with darker iris color (RR = 4.9), myopia (RR = 2.8), history of diabetes (RR = 1.6), leaner body mass (RR = 0.95 for each unit increase in body mass index [kg/m(2)]), and intraocular pressure (IOP)-lowering treatment (RR = 2.7), mainly with topical beta-blockers. Treated participants had a threefold RR of nuclear opacities (RR = 3.2; 95% CI, 1.6, 6.5) compared with those untreated and with IOP < or =21 mmHg. Among participants with IOP >21 mmHg, those receiving treatment (n = 33) had a fivefold RR (RR = 5.0; 95% CI, 1.7, 15.1) versus those who were untreated. The RR was similar for treated persons with and without open-angle glaucoma (RR = 3.1; 95% CI, 1.3, 7.4 and RR = 2.8; 95% CI, 0.9, 8.6 respectively) but was lower in persons with newly detected (and thus untreated) glaucoma at baseline (RR = 1.2; 95% CI, 0.6, 2.6) compared with those without open-angle glaucoma or treatment. CONCLUSIONS The 4-year risk of nuclear opacities increased with age, female gender, darker iris color, myopia, diabetes, and leaner body mass, indicating similarities with other populations. The use of topical IOP-lowering medications tripled the RR of nuclear opacities in this study, an association that requires verification from clinical trials.

Patterns of open-angle glaucoma in the Barbados Family Study

OBJECTIVE To describe the Barbados Family Study of open-angle glaucoma (OAG) and present risk factors for OAG in siblings of study probands. DESIGN Observational study of families of probands with OAG. PARTICIPANTS Two hundred thirty probands and 1056 relatives (from 207 families). METHODS Probands and their family members underwent standardized examinations, including automated perimetry, applanation tonometry, ophthalmologic evaluation, fundus photography, blood pressure, interview, and genotyping. Generalized estimation equation methods were used to evaluate risk factors. MAIN OUTCOME MEASURES Presence of OAG in the relatives, as defined by both visual field and optic disc findings, after ophthalmologic exclusion of other causes. RESULTS The median ages of probands and relatives were 68 and 47 years, respectively. In the 207 families, 29% of the probands had one relative with OAG and 10% had two or more relatives affected. Of the 1056 family members, 10% had OAG, 13% had suspect OAG, and 6% had ocular hypertension. One fifth of the 338 siblings had OAG (n = 67); they tended to be older and more often were male. Multivariate comparisons between siblings with and without OAG found that age, higher intraocular pressure (IOP), myopia, and lower diastolic blood pressure-IOP differences were related to OAG, whereas hypertension and diabetes were not. CONCLUSIONS Based on standardized protocols and examinations, approximately one quarter of the relatives had OAG or suspected OAG, despite their relatively young age. Risk factors for OAG in siblings were similar to risk factors in unrelated individuals. Analyses are ongoing to determine OAG inheritance and to localize potential gene(s) involved.

Diabetic retinopathy in a black population ☆: The Barbados eye study

OBJECTIVE The distribution of diabetic retinopathy in black populations is largely unknown. The authors present retinopathy data from the predominately black participants of the Barbados Eye Study (BES). DESIGN AND PARTICIPANTS Prevalence study of 4631 participants based on a random sample of the Barbados population 40 to 84 years of age (84% participation). MAIN OUTCOME MEASURES Diabetes was defined as self-reported history of physician-diagnosed diabetes or glycosylated hemoglobin greater than 10% (>2 standard deviations above the population mean of persons without a diabetes history). Retinopathy was assessed by independent gradings of 30 degrees color stereo fundus photographs of the disc and macula. RESULTS Diabetes was present in 19.4% of black (n = 4314), 15.2% of mixed (black and white; n = 184), and 7.5% of white/other (n = 133) self-reported racial groups. In the black/mixed population, regardless of diabetes status, the prevalence of retinopathy was 5.9%. In the 636 black and mixed participants with diabetes, the prevalence of retinopathy was 28.5%: 19.8% had minimum changes, 7.7% had moderate changes, and 0.9% had severe retinopathy. Clinically significant macular edema (CSME) was found in 8.6% of those with diabetes. CONCLUSIONS In the population of African origin, approximately 1 in 17 persons had retinopathy. Among those with diabetes, 28.5% had retinopathy and 8.6% had CSME. These results highlight the clinical and public health relevance of diabetic retinopathy in the black population.

Incidence and progression of lens opacities in the Barbados Eye Studies

OBJECTIVE To provide 4-year cumulative incidence and progression rates of age-related lens opacities in a population > or =40 years of age, which is mainly of African origin. DESIGN Cohort study that reexamined surviving members of the population-based Barbados Eye Study 4 years after baseline. PARTICIPANTS Three thousand four hundred twenty-seven members of the Barbados Eye Study cohort (85% of those eligible). MAIN OUTCOME MEASURES The Lens Opacities Classification System II (LOCS II) was used at the slit lamp. Cumulative incidence was defined as the development of any nuclear, cortical or posterior subcapsular (PSC) opacities (LOCS II scores > or =2) among persons without that opacity type at baseline. Cumulative progression was defined by at least two-step increases in scores among persons with preexisting lens opacities. RESULTS The incidence of cortical opacities was about five times greater in black than white participants (age-gender adjusted relative risk = 4.7; 95% confidence interval: 1.9-11.4). In the black population, the 4-year incidence rates were 22.2% (20.4%-24.0%) for any cortical, 9.2% (8.2%-10.4%) for any nuclear, and 3.3% (2.7%-4.0%) for any PSC opacities; rates increased greatly with age. Four-year progression rates were 12.5% for cortical, 3.6% for nuclear, and 23.0% for PSC opacities, without consistent pattern by age. Women had a greater risk of cortical and nuclear opacities (P<0.05) than men and greater progression of nuclear opacities. The presence of PSC opacities at baseline seemed to at least double the incidence and progression rates of other opacities. In persons initially opacity free, single cortical opacities were the predominant type to develop at followup. Visual acuity loss frequently accompanied incident opacities. CONCLUSIONS This longitudinal study provides new population-based data on the natural history of lens opacities. Incidence and progression of opacities, especially of cortical opacities, were high. After 4 years of followup, 1 in 4 to 5 participants developed cortical opacities, 1 in 11 developed nuclear opacities, and 1 in 30 developed PSC opacities. The information obtained attests to the public health impact of age-related cataract, as well as its extent, in this and similar black populations.

Open-angle glaucoma and ocular hypertension: The Long Island Glaucoma Case-control Study

This case-control study evaluated risk factors for open-angle glaucoma (OAG) and high intraocular pressure (IOP), including systemic hypertension and its treatment, other systemic factors, familial, and demographic variables. The three study groups were based on masked ophthalmologic gradings of visual fields and fundus photographs, as well as tonometry. The OAG group (n = 122) had OAG field defects, IOP > 21 mmHG, and cup-disc ratios > or = 0.5 and/or evidence of glaucoma disc damage. The ocular hypertensives (n = 108) had no field defects, IOP > 21 mmHg and normal discs. The controls (n = 190) had no field defects, IOP < 21 mmHg and normal discs. The data collection protocol included a standardized interview and measurements. Medical history was confirmed by contacting the primary care physicians (89% response from physicians). Study groups were compared by polychotomous logistic regression analyses. Men were more likely to have OAG and less likely to have ocular hypertension. Systemic hypertension was more frequent in ocular hypertensives (Odds Ratio = 2.36); high diastolic pressure was associated with OAG and ocular hypertension (OR = 2.13 and 2.21, respectively). Treatment for systemic hypertension was unrelated to OAG risk. Low perfusion pressures (blood pressure-IOP differences) were strongly associated with OAG and ocular hypertension, a finding that could be due to the high IOP in these groups. A family history of glaucoma was more frequent in OAG (OR = 3.08) and ocular hypertension (OR = 2.38) than in controls. Alcohol consumption was related to ocular hypertension (OR = 2.32). No other associations were significant. The results confirm an association of blood pressure with intraocular pressure. Since the OAG and ocular hypertensive groups had similar blood pressure results, an independent effect of blood pressure on OAG was not substantiated.

Admixture and Population Stratification in African Caribbean Populations

Throughout biomedical research, there is growing interest in the use of ancestry informative markers (AIMs) to deconstruct racial categories into useful variables. Studies on recently admixed populations have shown significant population substructure due to differences in individual ancestry; however, few studies have examined Caribbean populations. Here we used a panel of 28 AIMs to examine the genetic ancestry of 298 individuals of African descent from the Caribbean islands of Jamaica, St. Thomas and Barbados. Differences in global admixture were observed, with Barbados having the highest level of West African ancestry (89.6%± 2.0) and the lowest levels of European (10.2%± 2.2) and Native American ancestry (0.2%± 2.0), while Jamaica possessed the highest levels of European (12.4%± 3.5) and Native American ancestry (3.2%± 3.1). St. Thomas, USVI had ancestry levels quite similar to African Americans in continental U.S. (86.8%± 2.2 West African, 10.6%± 2.3 European, and 2.6%± 2.1 Native American). Significant substructure was observed in the islands of Jamaica and St. Thomas but not Barbados (K=1), indicating that differences in population substructure exist across these three Caribbean islands. These differences likely stem from diverse colonial and historical experiences, and subsequent evolutionary processes. Most importantly, these differences may have significant ramifications for case‐control studies of complex disease in Caribbean populations.