Lower urinary cotinine level is associated with a trend toward more myopic refractive errors in Korean adolescents

Abstract

PurposeTo investigate the association between urinary cotinine levels as an objective biological marker for exposure to nicotine and refractive status.Patients and methodsThis cross-sectional study analyzed data from the Korea National Health and Nutrition Examination Survey between 2008 and 2011. A total of 1139 Korean adolescents aged 12-18 years were enrolled. Urinary cotinine concentrations and other potential risk factors for myopia were examined. Correlation analyses and multivariate regression analysis were performed to investigate the association between urinary cotinine level and refractive error.ResultsSpherical equivalent correlated significantly with urinary cotinine concentration (r=0.104, P=0.011). Lower urinary cotinine level was associated with a trend toward more myopic refractive errors (P for trend=0.003). After adjusting for age, sex, area of residence, physical activity, serum 25-hydroxyvitamin D level, parental income level, and receipt of basic livelihood security, subjects with a low urinary cotinine level had a significantly increased risk of myopia <-0.5 D (odds ratio (OR) 1.95, 95% confidence interval (CI) 1.18-3.21), <-3.0 D (OR 2.03, 95% CI 1.29-3.2), and <-6.0 D (OR 2.2, 95% CI, 1.15-4.23) when compared with subjects with a high urinary cotinine level. As urinary cotinine level decreased, the risks of myopia <-0.5 D, <-3.0 D, and <-6.0 D increased significantly (P for trend <0.05).ConclusionA trend toward less myopic refractive error was observed among Korean adolescents with higher urinary cotinine levels. This result provides the epidemiologic evidence implying nicotine as a potential modulator related with refractive development. Further studies with full consideration for myopia-associated risk factors are required to yield clear answers on the direct effect of smoking to the refractive status.

Risk Factors for Myopia: Putting Causal Pathways into a Social Context

“…A similar protective relationship was reported in a sample from a pediatric ophthalmology clinic, which largely persisted after adjustment for a range of factors including child's near work activity and parental myopia and education [167]. A detailed study from South Korea reported consistent results for exposure to passive smoke estimated from urinary cotinine level [168], supporting the suggestion that nicotinic pathways are involved in the regulation of eye growth. In contrast, Rahi et al reported a positive association between maternal smoking in early pregnancy and more myopia [47].…”

Updates on Myopia

“…The long-term outcome of CNV is poor if left untreated. In a 10-year follow-up study of 25 patients with myopic CNV, visual acuity deteriorated to 20/200 or worse in 89% and 96% of eyes in 5 years and 10 years, respectively [168].…”

“…Myopic choroidal neovascularization (myopic CNV) is the second most common cause of CNV after age-related macular degeneration (AMD) [167,168]. It is one of the most sight-threatening complications of pathological myopia [119,169] and is the most common cause of CNV in those 50 years or younger [167], with significant social and economic burden.…”

“…It is one of the most sight-threatening complications of pathological myopia [119,169] and is the most common cause of CNV in those 50 years or younger [167], with significant social and economic burden. The prevalence of myopic CNV is between 5.2% and 11.3% in individuals with pathological myopia [12], with female preponderance seen in most studies [167][168][169][170]. The long-term outcome of CNV is poor if left untreated.…”

“…On slit-lamp biomicroscopy, myopic CNV manifests as a small, flat, grayish subretinal lesion adjacent to or beneath the fovea [109,168,169,171]. On SD-OCT, myopic CNV presents as a hyper-reflective material above the retinal pigment epithelium band (type 2 CNV), with variable amount of subretinal fluid.…”