Eyeworld

EW INTERNATIONAL 92 February 2017 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer More evidence Heavy alcohol consumption signifi- cantly increased the risk of age-re- lated cataract, whereas moderate consumption was seen as poten- tially protective against cataract, according to the results of a recent meta analysis. 1 The investigation searched PubMed and Embase from their inception until May 2014 and identified five case-control and five cohort studies that provided data on alcohol consumption and age-related cataract. Heavy alcohol consumption was defined as more than two standard drinks per day (20 g alcohol/day) and moderate consumption defined as less than 20 g of alcohol per day but more than never any alcohol. Adjusting for smoking as a potential confounder attenuated the association between heavy alcohol consumption and cataract. While this evidence sup- ports the observations made in the EPIC-Norfolk study regarding the benefits of moderate alcohol con- sumption, further studies examining the potential relationship between alcohol consumption and cataract are required, Dr. Khawaja said. He explained, "The dose-re- sponse relationship supports a casual association. Residual confounding may also explain the association, e.g., by social class. There were very few heavy drinkers in our cohort, so our results only apply to mild and moderate alcohol consumption. The association with alcohol may be driven by factors related to undergo- ing surgery in general, like access to care, rather than the development of visually significant cataract." EW Reference 1. Gong Y, et al. Different amounts of alcohol consumption and cataract: a meta-analysis. Optom Vis Sci. 2015;92:471–9. Editors' note: Dr. Khawaja has no financial interests related to his comments. Contact information Khawaja: anthony.khawaja@gmail.com The first step of the investiga- tion included the entire cohort. It revealed that alcohol consumers were less likely to undergo cataract surgery than non-alcohol consum- ers (P<0.00001). The multivariable adjusted hazard ratio for alcohol consumption versus non-consump- tion was 0.92 (95% CI 0.85–0.92; P=0.015). The second step included the data from the alcohol consumers only. A dose-response effect was evident among alcohol consumers: The risk of undergoing cataract surgery was progressively reduced with greater alcohol consumption (P=0.002 for trend). Participants in the highest quartile of alcohol intake were at 16% less risk of inci- dent cataract surgery compared to participants in the lowest quartile of intake (hazard ratio 0.86 [95% CI 0.78–0.96; P=0.005]). A subgroup analysis according to the type of alcohol intake was found to have a significant asso- ciation with alcohol among wine drinkers only, but not beer or spirit drinkers. Participants in the highest tertile of wine consumption were 18% less likely to undergo cataract surgery than participants in the lowest tertile of wine consumption (hazard ratio 0.85 [95% CI 0.76– 0.94; P=0.001]). "Examining the epidemiological association with alcohol consump- tion is problematic, as non-drinkers are potentially different to drinkers in aspects other than alcohol use. We carried out a two-step anal- ysis. In step one, we compared drinkers of any amount of alcohol to non-drinkers, and in step two, among drinkers, we examined for a dose response of effect by compar- ing across quartiles of intake," Dr. Khawaja said. The study also plotted Kaplan-Meier survival curves and comparisons between groups using the log-rank test. Cox proportion- al hazards regression was used to examine associations adjusted for potential confounders, such as age, sex, social class, BMI, diabetic status, and smoking status. cohort study's aim is to understand the connection among diet, lifestyle factors, and cancer, with a wid- ened spectrum that includes other conditions as well, such as cataract, and the factors that may or may not affect its development. EPIC pro- vides data-based evidence for health policies to prevent or delay disease onset. The participants in the EPIC- Norfolk population-based study are men and women who joined the study between the ages of 40 to 79, who live in the area of Norwich, and have been contributing informa- tion about their diets, lifestyles, and health through questionnaires for more than 20 years. In all, 25,639 patients were recruited and exam- ined in the time period from 1993 to 1997. In total, 22,848 participants were included in analyses following the exclusion of participants report- ing cataract at baseline (n=1,138) or with missing data for any covari- ables. The mean participant age was 59 years, 46% of the participants were men, and 54% were wom- en. The mean length of follow-up until cataract surgery or censoring (death or end of data linkage period) was 193 months (range 1 to 265 months). The participants' usual alcohol consumption was measured using a validated food frequency ques- tionnaire. Incident cataract surgery was defined as cataract surgery in either eye, and the date of the event defined as the date of the first eye cataract surgery in participants un- dergoing bilateral surgery. The study region of Norfolk is served by one major hospital, and incident cataract surgery was ascertained by linkage with hospital records. Results A total of 4,497 (19.7%) participants underwent cataract surgery in at least one eye, since baseline. The baseline characteristics were even between participants undergoing cataract surgery and controls including sex distribution, BMI, non-manual oc- cupation versus manual occupation, diabetic versus non-diabetic, and their smoking status. The EPIC-Norfolk study concludes that moderate alcohol intake may provide protection against cataract development I t seems that moderate alcohol intake may protect the eyes against the development of cataract, according to a popu- lation-based study that inves- tigated alcohol consumption and incident cataract surgery in a large adult cohort of more than 25,000 participants. The data were collected via food frequency questionnaires as part of the European Prospective Investigation of Cancer (EPIC)- Norfolk prospective cohort study and presented at a poster session at the 2016 annual meeting of the American Academy of Ophthalmol- ogy (AAO). Presenting his work on behalf of the Department of Public Health & Primary Care, University of Cambridge, and NIHR Biomedical Research Centre for Ophthalmolo- gy, Moorfields Eye Hospital and the University College London, London, U.K., Anthony Khawaja, PhD, FRCOphth, said that understanding lifestyle risk factors for cataract can teach us about etiological mech- anisms and help inform public health strategies. He explained that while cataract remains the most common cause of blindness in the world today, we only recognize age as a strong risk factor for cataract development. Having said that, Dr. Khawaja noted that people develop cataract at different ages, and some people will not even require cataract surgery in their lifetime. Without continued research on the factors affecting cataract, the fact remains that the biological processes under- lying the development of cataract continue to be unclear. EPIC-Norfolk The EPIC-Norfolk study, based at the University of Cambridge, is one of the U.K.'s arms of EPIC, the largest study of diet and health ever under- taken, involving the participation of more than half a million people in 10 countries. The large multicenter "EPIC" results give a good reason to celebrate Presentation spotlight

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