Impact of cigarette smoking on fluorescence lifetime of ocular fundus

Cigarette smoking is known to adversely affect cellular metabolism and is a risk factor for various retinal diseases. Fluorescence lifetime imaging ophthalmoscopy (FLIO) has the potential to detect metabolic changes in the ocular fundus. Aim of this study was to analyze the influence of cigarette smoking on fluorescence lifetime (FLT) of healthy eyes using FLIO. Twenty-six non-smokers and 28 smokers aged between 20 and 37 years without systemic and ocular diseases were investigated by FLIO (excitation: 473 nm, emission: short spectral channel (SSC) 498–560 nm, long spectral channel (LSC) 560–720 nm). The FLT at the ETDRS grid regions were analyzed and compared. In SSC, the mean FLT (τ(m)) of smokers was significantly longer in the ETDRS inner ring region, whereas the τ(m) in LSC was significantly shorter in the outer ring. For the long component (τ(2)), smokers with pack year < 7.11 showed significantly shorter τ(2) in SSC than non-smokers and the smokers with pack year ≥ 7.11. There were no significant differences in retinal thickness. The lack of obvious structural differences implies that the observed FLT changes are likely related to smoking-induced metabolic changes. These results suggest that FLIO may be useful in assessing retinal conditions related to lifestyle and systemic metabolic status.