New cases of myopia in children.

OBJECTIVE: To report the percentage of new cases of myopia in 4927 children aged 5 to 16 years who participated in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study between 1989 and 2009. DESIGN: A multicenter, longitudinal, observational, volunteer study of refractive error and ocular development in children from 5 racial/ethnic groups in which the participants were children who were not myopic (right eye cycloplegic auto refraction of less myopia/more hyperopia than -0.75 diopters [D] in both principal meridians) at study entry. A new case was a diagnosis of myopia (right eye cycloplegic auto refraction of -0.75 D or more myopia in both principal meridians) after study entry. RESULTS: Of the 4556 children entering the study who were not myopic, 749 (16.4%) received a diagnosis of myopia after study entry. Among these 749 children, the ages of the participants at diagnosis varied from 7 to 16 years, with the largest number diagnosed at age 11 years(136 participants [18.2%]). New cases of myopia occurred in 27.3% of Asians, 21.4% of Hispanics, 14.5% of Native Americans, 13.9% of African Americans, and 11% of whites. Female participants had more new cases than did male participants (18.5% vs 14.5%). Normal-birth weight children had more new cases than did low-birth weight children (16.9% vs 15.5%). CONCLUSIONS: Sixteen percent of children enrolled in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study developed myopia during their school-aged years. The percentage increased yearly until age 11 years, after which it decreased. New cases of myopia varied by ethnic/racial group.

Visual activity before and after the onset of juvenile myopia.

PURPOSE: To investigate visual activities before and after the onset of juvenile myopia. METHODS: The subjects were 731 incident myopes (-0.75 D or more myopia on cycloplegic autorefraction in both meridians) and 587 emmetropes (between -0.25 and +1.00 D) in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. Parents supplied visual activity data annually. Data from myopic children 5 years before through 5 years after myopia onset were compared to data from age-, sex-, and ethnicity-matched models of children who remained emmetropic. RESULTS: Hours per week spent reading or using a computer/playing video games did not differ between the groups before myopia onset; however, hours per week for both activities were significantly greater in myopes than in emmetropes at onset and in 4 of the 5 years after onset by 0.7 to 1.6 hours per week. Hours per week spent in outdoor/sports activities were significantly fewer for children who became myopic 3 years before onset through 4 years after onset by 1.1 to 1.8 hours per week. Studying and TV watching were not significantly different before myopia onset. CONCLUSIONS: Before myopia onset, near work activities of future myopic children did not differ from those of emmetropes. Those who became myopic had fewer outdoor/sports activity hours than the emmetropes before, at, and after myopia onset. Myopia onset may influence children's near work behavior, but the lack of difference before onset argues against a major causative role for near work. Less outdoor/sports activity before myopia onset may exert a stronger influence on development than near work.