People with Type 2 diabetes who drink alcohol are at increased risk for blurry vision unrelated to retinopathy….
A new study showed that moderate drinking did not increase the risk for or progression of retinopathy in a study of more than 1,200 diabetics, but it nearly doubled the risk of losing two eye-chart lines of visual acuity over an average of five years.
Joline W.J. Beulens, PhD, of University Medical Centre Utrecht in the Netherlands, and colleagues write that, “Multivariate analysis yielded an odds ratio of 1.83 (95% CI 1.34 to 2.48) for a two-line loss of acuity in participants reporting one to 14 drinks a week compared with those who don’t drink.”
Heavy drinking (more than 14 drinks a week) was also associated with two-line acuity losses to about the same degree (adjusted OR 2.09, 95% CI 1.28 to 3.40), the researchers found.
They calculated that each additional drink per week increased the risk of two-line acuity loss by 2%.
Retinal vascular lesions as detected by mydriatic stereoscopic photography, on the other hand, were no more common in diabetics who drank than in those who didn’t, with odds ratios of 0.88 and 1.08 for moderate and heavy drinking, respectively.
Beulens and colleagues had no definitive explanation for the association of drinking with acuity loss in the absence of an effect on retinopathy, but they offered some speculation.
“Alcohol is known for its neurotoxic properties, which could induce oxidative damage to the retina and the optic nerve, leading to visual loss,” they noted.
A bit of support for this mechanism came from the researchers’ finding that study participants who preferred beer or hard liquor tended to be at greater risk for acuity loss than wine drinkers. “The natural antioxidants in wine may partially offset the adverse effects of alcohol,” Beulens and colleagues suggested. Or, drinkers may have an unhealthier diet, with lower levels of vitamins essential for eye health, the researchers speculated.
They also acknowledged that drinkers in their sample differed from abstainers in socioeconomic status and lifestyle factors other than smoking and exercise, which were not measured in the study.
“If participants in lower social classes both drank more alcohol and were less able to afford glasses with prescription, this would overestimate the reported association between alcohol consumption and the decline of visual acuity as visual measurement was performed corrected by glasses or contact lens, or through a pinhole,” Beulens and colleagues wrote.
The analysis was a substudy of the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation) diabetes trial, involving 1,239 patients without previous history of invasive ophthalmic interventions, or severe cataracts or problems with pupillary contraction that would interfere with retinopathy measurement.
With a mean of 5.5 years of follow-up, 182 patients showed significant progression of retinopathy and 640 had retinal vascular lesions. A total of 693 lost two lines of corrected visual acuity in their best-functioning eye.
Two-line losses were seen in just over half of the 833 abstainers in the study and in two-thirds of the moderate drinkers and heavy drinkers.
The adjusted odds ratios controlled for age, sex, blood pressure, glycemic control, body mass index, smoking, duration of diabetes, and smoking status.
Limitations of the study included self-reported alcohol intake, possible inability to cooperate fully with visual acuity examination for those who consume more alcohol, and a small number of patients with retinopathy, which decreased the power of the study.
- Explain that among patients with Type 2 diabetes, those with even moderate alcohol consumption (1 to 14 drinks/week) had significant visual acuity loss over five years of follow-up but no difference in development or progression of retinopathy.
- Note that the overall number of patients who developed retinopathy was small, which limited the analysis.
Beulens J, et al “Association between alcohol consumption and diabetic retinopathy and visual acuity — the AdRem Study” Diabet Med 2010; 27: 1130-1137