Analysis of familial aggregation in total, against-the-rule, with-the-rule, and oblique astigmatism by conditional and marginal models in the Tehran eye study

Abstract

Purpose:The purpose was to determine the familial aggregation of the total, against-the-rule (ATR), with-the-rule (WTR), and oblique astigmatism by conditional and marginal models in the Tehran Eye Study.Materials and Methods:Total, ATR, WTR, and oblique astigmatism were studied in 3806 participants older than 5 years from August 2002 to December 2002 in the Tehran Eye Study. Astigmatism was defined as a cylinder worse than or equal to −0.5 D. WTR astigmatism was defined as 0 ± 19°, ATR astigmatism was defined as 90 ± 19°, and oblique when the axes were 20–70° and 110–160°. The familial aggregation was investigated with a conditional model (quadratic exponential) and marginal model (alternating logistic regression) after controlling for confounders.Results:Using the conditional model, the conditional familial aggregation odds ratios (OR) (95% confidence interval) for the total, WTR, ATRs, and oblique astigmatism were 1.49 (1.43–1.72), 1.91 (1.65–2.20), 2.00 (1.70–2.30), and 1.86 (1.37–2.54), respectively. In the marginal model, the marginal OR of the parent-offspring and sib-sib in the total astigmatism were 1.35 (1.13–1.63) and 1.54 (1.13–2.11), respectively; WTR 1.53 (1.06–2.20) and 1.94 (1.21–3.13) and; ATR 2.13 (1.01–4.50) and 2.23 (1.52-3.30). The model was statistically significant in sib-sib relationship only for oblique astigmatism with OR of 3.00 (1.25–7.20).Conclusion:The results indicate familial aggregation of astigmatism in the population in Tehran adjusted for age, gender, cataract, duration of education, and body mass index, so that the addition of a new family member affected with astigmatism, as well as having a sibling or parents with astigmatism, significantly increases the odds of exposure to the disease for all four phenotypes. This aggregation can be due to genetic and/or environmental factors. Dividing astigmatism into three phenotypes increased the odds ratios.

Screen Exposure during Early Life and the Increased Risk of Astigmatism among Preschool Children: Findings from Longhua Child Cohort Study

“…Previous studies have showed that children whose parents have myopia and/or astigmatism are at higher risk of astigmatism than those whose parents have good vision [15,16]. Analogous to this, astigmatism was more prevalent in children whose parents had poor uncorrected vision than in those whose parents had good uncorrected vision, regardless of the screen exposure status.…”

“…The routine vision screening of kindergarten children in Longhua District of Shenzhen and the survey of Longhua Children Cohort Study (LCCS) provided us an opportunity to evaluate the relationship between screen exposure during early life with astigmatism based on a life-course approach [14]. Given that parental history of refractive errors was associated with astigmatism [15,16], we also assessed the combined influence of parental eyesight and screen exposure on astigmatism among preschool children aged 2-7 years in Longhua District, Shenzhen, China.…”

Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium

“…The results of twin (Dirani et al 2008 ; Grjibovski et al 2006 ; Parssinen et al 2012 ; Teikari and O’Donnell 1989 ), family (Rakhshani et al 2012 ; Mash et al 1975 ) and molecular genetic studies (Fan et al 2011 ; Lopes et al 2013 ; Mackey et al 2011 ) suggest that astigmatism is highly heritable, as does its high prevalence in specific ethnic groups such as Native Americans (McKean-Cowdin et al 2011 ; Mohindra and Nagaraj 1977 ; Harvey et al 2010 ). For refractive astigmatism, the heritability has been estimated at 0.33 to 0.63 from twin studies (Hammond et al 2001 ; Grjibovski et al 2006 ; Parssinen et al 2013 ).…”