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Abstract

We compared the biomechanical properties of corneas in eyes of healthy chronic smokers and non-smokers. In this prospective, comparative, and cross-sectional study, 50 eyes of 50 healthy chronic smokers (Study group) and 50 eyes of 50 agematched, healthy non-smokers (Control group) were enrolled. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured intwo groups using the Ocular Response Analyzer (ORA). Differences in the corneal biomechanical properties were determined using an independent-samples t test. Urine samples were collected to measure urinary levels of cotinine. Correlations between the number of cigarettes smoked per day, smoking duration, age, and CH-CRF values in the smokers group were also evaluated. Mean CH was 10.63±2.08 (SD) mmHg and 10.57±1.45 mmHg and the mean CRF was 10.53±1.81 mmHg and 10.27±1.77 mmHg in the smoker and control groups, respectively (p>0.05). CH and CRF were not correlated with the number of cigarettes smoked per day, smoking duration, or age. The findings indicate that cigarette smoking does not affect corneal biomechanical parameters such as CH and CRF. In addition, CH and CRF are not affected by the number of cigarettes smoked per day, smoking duration, or age. Keywords 2/4 Results and Discussion Demographic FindingsIn this study, 50 eyes of 50 healthy chronic smokers admitted to our department were included. As a control group, 50 eyes of 50 age-matched, healthy non-smokers were included. The mean ± SD age of the included subjects was 36.28±5.91 years (range 28-48) and 35.02±5.83 years (range 27-49 years) for the smokers group and the non-smokers group, respectively (p ˃0.05). On average, smokers smoked 16.70±8.00 (range 10-30) cigarettes per day and had been smoking for 12.20±3.01 (range 10-20) years.). The characteristics of the two groups of subjects are shown in (Table 1). There were no statistically significant differences between the two groups with regard to gender, AL, and CCT distributions (p˃0.05).Cotinine levels in the urine were 44.2±9.8 ng/ml in nonsmokers and 2439±451 ng/ml in smokers (p˂0.05). These data clearly indicate that the smokers were accurately selected, because the urine cotinine concentration in nonsmokers is normally below 500 ng/ml [14]. Biomechanical Parameters (CH and CRF) Urinary Cotinine ConcentrationTo distinguish objectively between smokers and nonsmokers, it was necessary to determine the level of cotinine in the urine. Cotinine, the major metabolite of nicotine, has a half life of 24 hours and is readily detectable in the smoker's urine even several days after the smoker has terminated smoking. Urine samples were collected in clean plastic containers to measure urinary levels of cotinine [11], and the basic technique used was based on spectrophotometric assessment at wavelength 532 nm. Laboratory workups were performed in the laboratory of the Kanuni Sultan Suleyman Education and Research Hospital. The influence of diuresis on urinary cotinine concentrations was corrected using the method described by T...