Axial Length and its Associations in an Adult Japanese Population: The Funagata Study

Abstract

Purpose: To describe the distribution of axial length (AxL) and its associations in an adult Japanese population sample, the Funagata Study.

Methods: The Funagata study is a population based epidemiologic study of Japanese aged 35+ years. We used 1219 data from participants of ophthalmological examination in 2010-2012 (33.19% of eligible). AxL was obtained using a partial coherence laser interferometry (OA-1000, TOMEY cooperation, Nagoya, Japan). Body height and weight were measured while subject were wearing light clothing without shoes. Body mass index BMI was calculated as body weight (kg) divided by the square of body height (m). Other information including physical activity, smoking, frequency of alcohol consumption, and time spent watching television per day were collected from a self-reporting questionnaire. Risk associations of the AxL were determined using multiple linear regression models. We used logarithm transformed AxL in this analysis, because AxL was deviated from normal distribution (Kolmogorov-Smirnov test p<0.01). We first analyze the data for right eyes, and then repeated the analysis for left eyes to confirm the result from right eyes.

Results: In multivariable adjusted model, younger age (0.002mm per 10 year of age, 95%CI 0.001 to 0.004), taller body height (0.012mm per 10cm in body height, 95%CI 0.003 to 0.021), and lower level of physical activity were independently associated with longer axial length. The body height-specific AxL and 95% range for <149 cm, 150-159 cm, 160-169 cm, and >170 cm were 21.04-25.82 mm, 21.74-26.28 mm, 21.95-26.74 mm, and 23.38-27.61 mm, respectively.

Conclusions: Younger age, taller body height, and lower physical activity were associated with longer AxL. Longitudinal study examining association between lower physical activity and longer axial length are warranted because this might identify potential intervention to prevent myopia.

Keywords: 605 myopia • 464 clinical (human) or epidemiologic studies: risk factor assessment • 676 refraction