• Age-related macular degeneration (AMD) accounts for 8.7% of blindness worldwide, making it a leading cause of blindness in western countries. In the next 20 years, the prevalence of AMD is expected to rise by 47%.
• It is crucial to identify causal, modifiable risk factors for advanced AMD before applying preventative measures.
• A two-sample mendelian randomisation (MR) was conducted; summary-level data of genetic variants were obtained from study samples that did not overlap with those for advanced AMD and its subtypes associated with certain genetic variants (Figure 1).

• The largest genome-wide association studies (GWAS) for these exposures yielded summary-level statistics for smoking features, alcohol intake, body mass index (BMI), blood pressure, and glycaemic traits.
• The study outcomes are explained in Figure 2.

AMD: Age-related macular degeneration; CI: Confidence interval; GA: Geographic atrophy; OR: Odds ratio; SD: Standard deviation.

• There was insufficient data to demonstrate that genetically predicted blood pressure, BMI, or glycaemic traits were related to advanced AMD.

Conclusion

In conclusion, according to genetic data:
• Increased alcohol consumption has a potential causal association with the risk of geographic atrophy (GA).
• Smoking initiation and lifetime smoking behaviour may be causally associated with the risk of advanced AMD.
• Smoking cessation reduces the risk of advanced AMD compared to continuing to smoke.
• These associations were stronger in the case of neovascular AMD than in the case of GA.

To lower the prevalence of advanced AMD in the elderly, public health campaigns and programmes promoting smoking cessation and reduced alcohol consumption should include information that these behaviours can lead to blindness.

Source:
Kuan V, Warwick A, Hingorani A, et al. Association of Smoking, Alcohol Consumption, Blood Pressure, Body Mass Index, and Glycemic Risk Factors With Age-Related Macular Degeneration: A Mendelian Randomization Study. JAMA Ophthalmol. 2021;139(12):1299–1306. doi:10.1001/jamaophthalmol.2021.4601

NON-2022-15053 - Date of creation January 2023