Quantitative fundus autofluorescence in smokers compared to non-smokers

Increased fundus autofluorescence is directly related to increased RPE lipofuscin deposition in the retina and has been observed in eyes with age-related macular degeneration (AMD). Smoking is the most significant modifiable risk factor for the development and progression of AMD, in which one of the main mechanisms is oxidative damage from smoking leading to RPE cell toxicity. The relationship between smoking and autofluorescence is not established and could provide insight into pathogenic mechanism of AMD. Therefore, our objective was to compare quantitative fundus autofluorescence (qAF) in the retinae of healthy non-smokers to smokers. We conducted a cross-sectional study at the 2016 Minnesota State Fair. Participants self-reported past medical and ocular history and underwent eye examination as well as qAF imaging with Spectralis confocal scanning laser ophthalmoscope (cSLO) equipped with an internal fluorescent reference. Two sets of images were obtained per eye. Stepwise multiple mixed effects regression model was used to examine the relationship between mean qAF values and smoking status. We enrolled 105 individuals (54 smokers, 61 females, mean age 41 years with range 18-78 years old). Fundus autofluorescence images were analyzable for 85 of 105 individuals contributing 161 eyes (80 right, 81 left). The repeatability coefficients between the first set and second set of images were +/- 21% of their mean qAF values. Older age and female gender were independently associated with higher qAF. Positive smoking history tended to result in higher qAF values after adjusting for age and gender but was not statistically significant (0.118, 95%CI -0.003, 0.240, P = 0.056). Among smokers, the number of pack-years smoked was not significantly associated with higher qAF. Our study's results are consistent with existing literature in which older age is predictive of intensified autofluorescence, while smoking history does not have as important of an impact on autofluorescence as hypothesized. Several large epidemiological studies have shown that smoking is significantly associated with AMD, and qAF is likely not the appropriate modality to clinically assess smoking's impact on retinae.