OBJECTIVE although numerous studies have reported the association between birth season and sex ratio, few studies have been conducted in subtropical regions in a non-Western setting. The present study assessed the effects of pregnancy season on birth sex ratio in China. METHODS We conducted a national population-based retrospective study from 2006-2008 with 3175 children-parents pairs enrolle...

PURPOSE To objectively determine the effects of pupil size on optical quality parameters in astigmatic eyes using a double-pass instrument. METHODS We examined twenty-two eyes of 22 healthy volunteers (mean age  ±  standard deviation, 27.1 ± 2.8 years) who had no ophthalmic diseases other than refractive errors (manifest cylinder ≤ 0.25 diopters (D)). After we fully corrected cycloplegic refr...

PURPOSE To explore the associations between anisometropia and spherical ametropia, astigmatism, age, and sex. METHOD Associations between the prevalence and magnitude of anisometropia with age, sex, spherical power, and cylindrical power, were assessed in a group of 90,884 subjects attending optometry practices in the United Kingdom. Logistic regression models were used to assess the independ...

Acute acquired comitant esotropia has been used to describe a dramatic onset of a relatively large angle of esotropia with diplopia and minimal refractive error. We describe six children aged 5 to 11 years who developed an acute non-accommodative esotropia with diplopia. Neurological examination, including CT scan, in each of these children gave negative results. We suggest that this is an unus...

PURPOSE To evaluate the factors affecting the area under the log contrast sensitivity function (AULCSF) in healthy myopic eyes. METHODS We retrospectively examined 201 eyes of 201 consecutive subjects (age, 31.8 ± 7.4 years (mean ± standard deviation)) with myopic refractive errors of -1.25 to -8.25 diopters (D). From the contrast sensitivity data, the area under the log contrast sensitivity ...

Changes in ocular axial dimensions and refraction were followed longitudinally, using ultrasonography and retinoscopy, during the first year of life (mean ages 4-53 weeks) of a group of 20 full-term infants (10 male, 10 female). Using a mixed-model regression analysis, axial length changes as a function of time were found to be best described by a quadratic expression (AL=17.190+0.128x-0.0013x(...

PURPOSE The relationship between refractory errors and intelligence and the importance of genetic, regional and environmental factors in such associations, were investigated in a group of school children. SUBJECTS AND METHODS One hundred and thirty-seven students (34.3% boys and 65.7% girls) from two primary schools were enrolled in the study. Cycloplegic refraction was performed and a spheri...

IMPORTANCE Myopia has reached epidemic levels in parts of East and Southeast Asia. However, there is no effective intervention to prevent the development of myopia. OBJECTIVE To assess the efficacy of increasing time spent outdoors at school in preventing incident myopia. DESIGN, SETTING, AND PARTICIPANTS Cluster randomized trial of children in grade 1 from 12 primary schools in Guangzhou, ...

PURPOSE Chicks' eyes rapidly compensate for defocus imposed by spectacle lenses by changing their rate of elongation and their choroidal thickness. Compensation may involve internal emmetropization signals that rise and become saturated during episodes of lens wear and decline between episodes. The time constants of these signals were measured indirectly by measuring the magnitude of lens compe...

Myopia is emerging as a major public health issue due to its increasing prevalence and long-term pathological outcomes. Prevention must focus on limiting excessive axial elongation which is the cause of both myopic refractive error and its pathological outcomes. The increasing prevalence appears to be due to environmental changes involving near work, rather than to a genetic failure of emmetrop...