Smoking history and the incidence of age-related macular degeneration--results from the Muenster Aging and Retina Study (MARS) cohort and systematic review and meta-analysis of observational longitudinal studies.

To compare the association of smoking with age-related macular degeneration (AMD) in the Muenster Aging and Retina Study (MARS) cohort with current evidence. Adjusted risk ratios for incident AMD in MARS were compared with findings of a systematic review and meta-analysis of observational prospective studies. 9.6% of MARS participants progressed to AMD over a median of 30.9 months. In MARS the adjusted risk ratio in current versus never smokers was 3.25 (95% confidence interval [1.50-7.06]), and 1.28 [0.70-2.33] in former smokers versus never smokers. The meta-analysis of previous studies showed a pooled adjusted risk ratio of 2.51 [1.09-5.76] in current versus never smokers. Inclusion of the MARS findings removed between-study heterogeneity and accentuated the pooled adjusted risk ratio for current smokers to 2.75 [1.52-4.98]. Specific analyses in MARS revealed a protective effect for time since smoking cessation in former smokers with an adjusted risk ratio=0.50 [0.29-0.89] per log(year). Current smoking nearly triples AMD incidence, while smoking cessation lowers AMD incidence in a non-linear fashion even in the elderly.