The relationship of retinal vessel diameter to changes in diabetic nephropathy structural variables in patients with type 1 diabetes.

AIMS/HYPOTHESIS: We examined whether retinal vessel diameter in persons with type 1 diabetes mellitus is associated with changes in subclinical anatomical and functional indicators of diabetic nephropathy. METHODS: Persons with type 1 diabetes mellitus had gradable fundus photographs and renal biopsy data at baseline and 5-year follow-up (n = 234). Retinal arteriolar and venular diameters were measured at baseline and follow-up. Central retinal arteriole equivalent (CRAE) and central retinal venule equivalent (CRVE) were computed. Baseline and 5-year follow-up renal structural variables were assessed by masked electron microscopic morphometric analyses from percutaneous renal biopsy specimens. Variables assessed included: mesangial fractional volume, glomerular basement membrane width, mesangial matrix fractional volume and glomerular basement membrane width composite glomerulopathy index. RESULTS: While controlling for other covariates, baseline CRAE was positively associated with change in the glomerulopathy index over the 5-year period. Change in CRAE was inversely related to a change in mesangial matrix fractional volume and abnormal mesangial matrix fractional volume, while change in CRVE was directly related to change in the volume fraction of cortex that was interstitium [Vv((Int/cortex))] over the 5-year period. Baseline CRAE or CRVE or changes in these diameters were not related to changes in other anatomical or functional renal endpoints. CONCLUSIONS/INTERPRETATION: Independently of other factors, baseline CRAE correlated with changes in glomerulopathy index, a composite measure of extracellular matrix accumulation in the mesangium and glomerular basement membrane. A narrowing of the CRAE was related to mesangial matrix accumulation. Changes in CRVE were related to changes in Vv((Int/cortex),) a measure of interstitial expansion in persons with type 1 diabetes mellitus.

Physical activity and the 15-year cumulative incidence of age-related macular degeneration: the Beaver Dam Eye Study.

BACKGROUND: Cardiovascular disease and age-related macular degeneration (AMD) may share common risk factors. Physical activity improves the cardiovascular risk profile; however, there have been few studies investigating a relationship between physical activity and the long-term incidence of AMD. METHODS: The 15-year cumulative incidence of AMD was determined through four examination phases at 5-year intervals of a population-based study conducted in Beaver Dam, Wisconsin, USA, initiated in 1988-90 (n = 3874 men and women between ages 43 and 86 years). Early AMD (pigment abnormalities or soft indistinct drusen), exudative AMD and geographic atrophy were determined by grading stereoscopic colour fundus photographs. Measures of physical activity were obtained through a questionnaire administered at the baseline examination. RESULTS: After controlling for age, sex, history of arthritis, systolic blood pressure, body mass index, smoking and education, people with an active lifestyle (defined as regular activity > or =3 times/week) at baseline were less likely to develop exudative AMD (odds ratio (OR) 0.3, 95% confidence interval (CI) 0.1 to 0.7) compared with people without an active lifestyle. After multivariate adjustment, increased categories of number of blocks walked per day decreased the risk of exudative AMD (OR 0.7, 95% CI 0.6 to 0.97). Physical activity was not related to the incidence of early AMD or pure geographic atrophy. CONCLUSIONS: These data show a protective effect of physical activity for incident exudative AMD, independent of body mass index and other confounders. They also suggest a possible modifiable behaviour that might be protective against developing AMD.

Intraocular pressure and systemic blood pressure: longitudinal perspective: the Beaver Dam Eye Study.

AIM: To investigate the relation between change in systemic blood pressures and change in intraocular pressure. METHODS: This was a population based study of people 43-86 years old living in Beaver Dam, Wisconsin. Measurements at baseline (1988-90) and 5 year follow up of systemic blood pressures, intraocular pressures, and history of use of blood pressure medications. RESULTS: Intraocular pressures were significantly correlated with systolic and diastolic blood pressures at both baseline and follow up. There were significant direct correlations between changes in systemic blood pressures and changes in intraocular pressure. There was a 0.21 (95% CI: 0.16 to 0.27) mm Hg increase in IOP for a 10 mm Hg increase in systolic and 0.43 (0.35 to 0.52) mm Hg increase in IOP for a 10 mm Hg increase in diastolic blood pressure. Further adjustment for diabetes and medication use did not alter these associations. Decreased systolic or diastolic blood pressures of more than 10 mm Hg over 5 years were significantly associated with decreased IOP. CONCLUSIONS: Reduced systemic blood pressure is associated with reduced intraocular pressure. This finding should be evaluated in other studies, especially with respect to the possibility of resultant decreased risk of open angle glaucoma.

Variation associated with measurement of retinal vessel diameters at different points in the pulse cycle.

BACKGROUND/AIMS: To assess the variability in retinal vessel measurements at different points in the pulse cycle. METHODS: A healthy white male aged 19 years had 30 digitised images taken at three distinct points in the pulse cycle over a one hour period. A pulse synchronised ear clip trigger device was used to capture images at the desired point in the pulse cycle. Two trained graders measured the retinal vessel diameter of one large arteriole, one large venule, one small arteriole, and one small venule 10 times in each of these 30 images. RESULTS: Within an image, variability was similar between graders, pulse point, and vessel type. Across images taken at the same point in the pulse period, the change from the minimum to maximum measurement was between 6% and 17% for arterioles and between 2% and 11% for venules. In addition, measurements of small vessels had greater changes than large vessels and no point in the pulse period was more variable than another. Ignoring pulse cycle increased variability across images in the large venule, but not in the other vessel types. Mixed effect models were fit for each of the vessel types to determine the greatest source of variability. Controlling for pulse point and grader, the largest source of variability for all four vessels measured was across images, accounting for more than 50% of the total variability. CONCLUSION: Measurements of large retinal venules is generally less variable than measurements of other retinal vessels. After controlling for pulse point and grader, the largest source of variation is across images. Understanding the components of variability in measuring retinal vessels is important as these techniques are applied in epidemiological studies.

Associations of selected medications and visual function: the Beaver Dam Eye Study.

AIM: To investigate association of drug use and visual function. METHODS: A cross sectional population based study was carried out on participants in the 1993-5 examination phase of the Beaver Dam Eye Study. All drugs in current use by study participants were recorded. Performance based and self assessed visual functions were obtained at the time of the study evaluation. The main outcome measure was the relation of levels of visual functions by use of specific drugs. RESULTS: Many classes of drugs were associated with decreases in at least two performance based visual functions. For example, high blood pressure drugs were significantly associated with poorer best corrected visual acuity, poorer near vision, and poorer contrast sensitivity (p<0.001 for all). Patterns of association for self assessed visual functions were not as strong. However, use of glaucoma drops and benzodiazepines were associated with poorer self assessed visual functions in most circumstances cited. CONCLUSIONS: Many commonly used medications are inversely associated with visual functions in a middle and older aged population. This may influence the ability to perform complex tasks and quality of life.

Assessing school readiness through the school-entry screening exam.

Although there exists no perfect screening tool that is predictive of a child's success in school, an office visit prior to school enrollment can detect potential problems. This visit should include a history and physical, and developmental assessment. The developmental assessment involves a sampling of a child's abilities in the areas of language, reasoning, gross and fine motor skills, and personal-social development. Providers must be alert to signs and symptoms indicating impediments to learning. Clinicians who are knowledgeable about trends in education regarding readiness testing, birth-date cutoffs and retention can serve as a valuable resource to parents. The clinician can also be a major contributor to the achievement of national education goals set forth by the Bush administration. Ten tools for assessing children are compared, and their appropriate use is discussed.