The microstructural and functional changes in the macula of heavy habitual smokers

To investigate whether heavy habitual smoking affects microstructures and functions of the macula, 45 age- (20-39 years old) and sex-matched adult smokers (≥1 box/day for ≥5 years) and 45 nonsmokers (controls) were enrolled in this case-control study. Central macular thickness (CMT), macular autofluorescent pigment density (MAPD), macular electroretinogram (ERG), and photostress recovery time (PRT) measurements were performed. The mean age of smokers and nonsmokers was 32.9 ± 3.9 and 33.1 ± 4.1 years, respectively (p = 0.43), and smoking duration was 11 ± 5.6 years. CMT in smokers (220 ± 28 μm) and nonsmokers (217.2 ± 31 μm; p = 0.57) was similar. Smokers had lower MAPD values (124.6) than nonsmokers (138.2) (p = 0.010). Multifocal ERG parameters in the central (6°) hexagon were similar in both groups (p > 0.05 for latency and amplitudes of P1 and N1). PRT in smokers and nonsmokers was similar (7.2 ± 1.2 and 7.4 ± 1.9 min, respectively; p = 0.33); however, foveal threshold value (FTV) at the first minute after photostress was statistically higher in smokers (36.1 ± 1.04 dB) than nonsmokers (34.8 ± 1.05 dB) (p = 0.011). We conclude that decreased MAPD and altered response to photostress may be indicative of early nicotine toxicity in microstructurally sound macula of adult chronic smokers.