Associations between dietary factors and diabetic retinopathy and the Optometrists' Practices in Advising about Lifestyle Study
Sahli, Michelle Wasserman
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Background : Epidemiologic studies have shown protective associations between both dietary factors and chronic eye diseases, but few studies have examined the associations between lutein or dietary patterns and diabetic retinopathy. Moreover, although lifestyle may influence eye health, there are only a small number of studies that have examined lifestyle advice offered to patients by optometrists, and these studies have focused primarily on advice provided on tobacco or dietary supplement use. Objectives : We examined the associations between dietary factors and diabetic retinopathy, a retinal microvascular complication of diabetes, and the leading cause of blindness in working aged individuals in the U.S. We then investigated the advice optometrists give their patients on lifestyle factors including diet and dietary supplementation. Methods : Our first two studies were conducted in individuals with diabetes from the Atherosclerosis Risk in Communities (ARIC) Study. Study 1 focused on dietary intake of lutein and Study 2 focused on adherence to a healthy diet. These studies evaluated the association between self-reported diet, assessed with a food frequency questionnaire, and the prevalence of diabetic retinopathy assessed with graded, fundus photographs taken six years later. Adherence to a healthy diet was assessed using both an index-based score based on the Mediterranean Diet, and a data driven approach using reduced rank regression to derive scores from the resulting factors. Our third study, the Optometrists’ Practices in Advising about Lifestyle (OPAL) Study, was conducted among optometrists in the Western New York region. We sought to describe the lifestyle advice these practitioners offer to patients via a survey administered by mail. Results : Our first two studies found increasing odds of prevalent retinopathy with increasing intake of lutein and increasing dietary pattern scores, indicating better adherence to a healthy diet, after adjusting for ARIC study field center, race, duration of diabetes, glycosylated hemoglobin levels, and energy intake. This association was only statistically significant in the healthy diet pattern analysis. In both analyses this association persisted only in those participants with a longer duration of diabetes (≥6 years). In those with a shorter duration of diabetes (>6 years) this association was attenuated and inverse (odds ratios <1.0 in those with greater intakes of lutein or better adherence to a healthy diet pattern vs. those with lesser intake of lutein or worse adherence to healthy diet pattern). In the OPAL Study, 42 optometrists out of 140 (30%) returned completed surveys. Most optometrists who enrolled in the study reported offering advice about smoking, diet, and dietary supplement use, but this advice was usually targeted to those reporting an undesirable level of a lifestyle factor or to those with certain health conditions. When advice was given, it most often consisted of mentioning that the lifestyle factor contributes to eye and/or overall health. Common reasons for not giving lifestyle advice were lack of proper training to offer such advice or the belief that the optometrists’ advice would do little to change patients’ behaviors. Conclusions : The observed increased odds of retinopathy with higher intake of lutein and better adherence to healthy diets are likely reflective of dietary changes in individuals after diagnosis with diabetes or diabetic complications before the start of our study. Our findings in participants with diabetes for a shorter period of time than 6 years suggest that lutein intake or healthy diets are not associated with increased odds of retinopathy. Further research is needed to better understand how diet changes after a diagnosis with diabetes or its complications. A potential change in diet in individuals newly diagnosed with diabetes or its complications could be due to advice given by one or more healthcare professionals and demonstrates that this advice may influence lifestyle behaviors. Optometrists are well placed to advise patients to participate in healthy lifestyles behaviors, and the majority of optometrists in our study did offer advice on lifestyle; however, due to low response rates, it is difficult to determine whether all optometrists offer lifestyle advice or if these findings were the result of selection bias. Future studies using techniques that are more likely to increase response rates in healthcare providers including optometrists are warranted. Public health professionals should ensure that all health care providers, not just physicians, have the necessary information and training to advise and refer patients on matters related to lifestyle change.