Cigarette Smoking is Negatively Associated With Keratoconus

Abstract

<h4>PURPOSE</h4><p> To investigate a correlation between cigarette smoking and keratoconus.</p> <h4>METHODS</h4><p>Patients with keratoconus who were treated with corneal collagen cross-linking from June 2006 to November 2007 were asked about their smoking habits. A person smoking a minimum of two cigarettes per day for more than 1 year was classified as a smoker.</p> <h4>RESULTS</h4><p>A total of 180 patients with keratoconus (mean age 28±9 years [range: 15 to 41 years]) were asked about their smoking habits. One hundred seventy-one (95%) were non-smokers and only 9 (5%) were smokers (95% confidence interval, 2.31 to 9.28). Using the chi-square test, a significant correlation was found between non-smokers and keratoconus (<i>P</i><.001). </p> <h4>CONCLUSIONS</h4><p>In this group of patients with keratoconus, few were smokers. Cigarette smoke contains toxic substances. Consequently, people are advised not to smoke. However, we speculate that the by-products of cigarette smoke may lead to cross-linking of collagen, which in the cornea, may prevent the development and progression of keratoconus. [<cite>J Refract Surg.</cite> 2008;24:S737-S740.]</p> <h4>ABOUT THE AUTHORS</h4> <p>From the Department of Ophthalmology (Spoerl, Raiskup-Wolf, Pillunat) and Institute of Medical Informatics and Biometry (Kuhlisch), Technical University Dresden, Germany.</p> <p>The authors have no commercial or proprietary interest in the materials presented herein.</p> <p>Presented in part at the International Congress of Corneal Cross-Linking; December 7-8, 2007; Zurich, Switzerland.</p> <p>Correspondence: Eberhard Spoerl, PhD, Dept of Ophthalmology, Carl Gustav Carus University Hospital, Fetscherstr 74, 01307 Dresden, Germany. Tel: 49 351 458 3763; Fax: 49 351 458 4335; E-mail: <a href="mailto:eberhard.spoerl@uniklinikum-dresden.de">eberhard.spoerl@uniklinikum-dresden.de</a> </p>

What Causes Keratoconus?

“…16 Factors that may reduce keratoconus risk include smoking, which seems to have a reduced prevalence in keratoconus patients and perhaps reduces the risk by increasing corneal collagen cross-linking. 50 Diabetic hyperglycemia may increase corneal collagen cross-linking as well, 51 and it seems that diabetic patients with keratoconus have less severe disease. 52 In reviewing the possible mechanisms of keratoconus formation associated with eye rubbing, we have discussed that epithelial trauma is a result of eye rubbing.…”

The Effects of Smoking on Anterior Segment Parameters, Retinal Nerve Fiber Layer, and Pupillary Functions

“…10 The authors claimed that tobacco smoking represents a source of advanced glycosylation products (AGEs), similar to diabetes mellitus. Also, in the study of Spoerl et al 9 smoking was found to be negatively associated with keratoconus due to increased cross-linking in the cornea.…”

“…Nishitsuka et al have reported that smoking is related to increased corneal thickness, and Spoerl et al proposed that cigarette smoking is negatively associated with keratokonus. 8,9 In this study, we have evaluated the anterior segment parameters and pupillary functions in heavy smokers, with optical low coherence reflectometry and a corneal-topographyaberrometer device respectively. Dry eye evaluation with Schirmer's test was also performed in these patients, and the results were compared to those in age-and gender-matched healthy control subjects.…”

The Role of Nonenzymatic Glycation and Carbonyls in Collagen Cross-Linking for the Treatment of Keratoconus

“…who underwent CXL showed lower incidence of keratoconus among smokers compared with non-smokers. 34 Cigarette smoke contains toxic substances that have been shown to increase the formation of AGEs in several tissues. 35 Furthermore, keratoconus tends to appear in patients early in life, before oxidative stress has produced significant numbers of AGE cross-links.…”