Abstract
Abstract: :
Purpose:Reduced levels of antioxidants have been demonstrated in smokers and it has been shown that nicotine and its major metabolite cotinine can liberate arachidonic acid, precursor to prostaglandins and pro–inflammatory mediators. Lipofuscin (LF) accumulates as a result of outer segments photoreceptor metabolism, and can be increased as a consequence of increased oxidative stress as in smoking. The purpose of this work was to test whether LF levels are affected by smoking status and sex in a population of ocularly normal subjects. Methods:We performed a retrospective study of 138 normal subjects between 20 and 70 years of age (74 females, 64 males). Smoking history was ascertained to estimate lifelong consumption in pack–years and date of smoking cessation for former smokers. Non–smokers were defined as either subjects who had never smoked or who had smoked less than 20 pack–years but had stopped smoking more than seven years prior to LF measurement. Smokers were defined as subjects who smoked 20 or more pack–years (either current or past smokers). Lipofuscin was measured photometrically, both at the fovea and at 7° temporal to the fovea. Signals resulting from extraneous fluorophores, macular pigment, and melanin were minimized by using an excitation at 550 nm; all measurement were individually corrected for crystalline lens. Since the rate of LF accumulation increases slightly with age, linearization of age was used to allow multiple regression analysis. Stepwise regression analyses were used to assess the effect of age, gender, smoking status and pigmentation on LF levels. Results:In all analyses, age is the strongest modulator of LF levels (p<0.0001). Neither sex nor smoking alone show an effect on LF accumulation, and no statistically significant effect of pigmentation was found on either test site. In the non smoker population a tendency was found for females to have higher LF levels compared to males (p=0.06). Stepwise regression analyses indicate higher LF levels in smoking females both at fovea (p=.002) and at 7° temporal (p=0.01). Conclusions:This study suggests that there may be an interaction between smoking and being female. As both being female and smoking have been cited in the literature as risk factor for developing AMD, these data support the hypothesis that LF may be related to AMD
Keywords: oxidation/oxidative or free radical damage • clinical (human) or epidemiologic studies: risk factor assessment • retina