Smoking and choroidal thickness in patients over 65 with early-atrophic age-related macular degeneration and normals

Abstract

Objective: To compare macular choroidal thickness between cigarette smokers, those with a history of smoking, and nonsmokers in patients over 65 years of age with early-atrophic age-related macular degeneration (AMD) and normals.

Methods: Prospective, consecutive, observational case series. Enhanced depth imaging spectral domain optical coherence tomography 12-line radial scans were performed and choroidal thickness manually quantified at 84 points in the central 3 mm of the macula. Data of normals, soft drusen alone, and soft drusen with additional features of early AMD were compared. A multivariate analysis of variance (MANOVA) model, controlling for age, was constructed to evaluate the effect of smoking history and AMD features on choroidal thickness.

Results: A history of smoking was significantly associated with a thinner choroid across all patients via logistic regression (P=0.004; O.R.=12.4). Mean macular choroidal thickness was thinner for smokers (148±63 μm) than for nonsmokers (181±65 μm) among all diagnosis categories (P=0.003). Subgroup analysis of patients with AMD features revealed a similar decreased choroidal thickness in smokers (121±41 μm) compared with nonsmokers (146±46 μm, P=0.006). Bivariate analysis revealed an association between increased pack-years of smoking and a thin choroid across all patients (P<0.001) and among patients with features of early AMD (P<0.001). Both the presence of features of macular degeneration (P<0.001) and a history of smoking (P=0.024) were associated with decreased choroidal thickness in a MANOVA model.

Conclusion: Chronic cigarette smoke exposure may be associated with decreased choroidal thickness. There may be an anatomic sequelae to chronic tobacco smoke exposure that underlies previously reported AMD risk.

Figure 1

Enhanced depth imaging optical coherence tomography of smokers and nonsmokers with early age-related macular degeneration and normal. (a) Normal control 72 year-old demonstrating normal retina and choroidal anatomy with mean central macular choroidal thickness (CMCT), 204 μm; (b) Normal 75 year-old with 18 pack-year history of smoking and mean CMCT, 91 μm; (c) 72 year-old nonsmoker with drusen and CMCT, 176 μm; (d) 76 year-old with 17 pack-year history of smoking and CMCT, 86 μm; (e) 78 year-old with drusen, pigmentary alteration, and subretinal drusenoid deposits and CMCT, 143 μm; (f) 77 year-old with drusen, pigmentary alteration, and subretinal drusenoid deposits as well as a 34 pack-year history of smoking with CMCT, 43 μm.

Figure 2

Comparison of mean macular choroidal thickness (CT) among smoking categories. (a) One-way analysis of variance (ANOVA) between lifetime nonsmokers, current smokers, and former smokers; green diamonds vertically centered on mean spanning 1 SD; horizontal width proportional to sample size; mean CT as follows: nonsmokers, 181±65, n=80; current smokers, 147±61, n=10; former smokers, 149±64 μm, n=57; P=0.011; (b) Two-sample t-test subgroup analysis of patients with drusen or early AMD; mean CT is as follows: nonsmokers, 146±46 μm, n=49; history of smoking, 121±41 μm, n=49; P=0.006.

Figure 3

Bivariate analysis of mean macular choroidal thickness by pack-year history of smoking. (a) Fit-line analysis across all patients; red line indicates overall mean, 166 μm; green line indicates fit-line analysis; mean macular choroidal thickness (μm), 186–1.76 (pack-years); (b) Subgroup analysis of patients with drusen or early-atrophic AMD; overall mean, 133 μm; mean macular choroidal thickness (μm), 147–1.02 (pack-years).