Ocular Component Development during Infancy and Early Childhood.

SIGNIFICANCE: The study fills an important gap by providing a longitudinal description of development of the major structural and optical components of the human eye from 3 months to nearly 7 years of age. Normative development data may provide insights into mechanisms for emmetropization and guidance on intraocular lens power calculation. PURPOSE: The purpose of this study was to describe the pattern of development of refractive error and the ocular components from infancy through early childhood. METHODS: Cycloplegic retinoscopy (cyclopentolate 1%), keratophakometry, and ultrasonography were performed longitudinally on between 162 and 293 normal birth weight infants at 0.25, 0.75, 1.5, 3, 4.5, and 6.5 years of age. RESULTS: Refractive error and most ocular components displayed an early exponential phase of rapid development during the first 1 to 2 years of life followed by a slower quadratic phase. Anterior and vitreous chamber depths, axial length, and crystalline lens radii increased at every visit. The crystalline lens thinned throughout the ages studied. The power of the cornea showed an early decrease, then stabilized, whereas the crystalline lens showed more robust decreases in power. The crystalline lens refractive index followed a polynomial growth and decay model, with an early increase followed by a decrease starting at 1 to 2 years of age. Refractive error became less hyperopic and then was relatively stable after 1 to 2 years of age. Axial lengths increased by 3.35 ± 0.64 mm between ages 0.25 and 6.5 years, showed uniform rates of growth across the range of initial values, and were correlated with initial axial lengths (r = 0.44, P < .001). CONCLUSIONS: Early ocular optical and structural development appears to be biphasic, with emmetropization occurring within the first 2 years of infancy during a rapid exponential phase. A more stable refractive error follows during a slower quadratic phase of growth when axial elongation is compensated primarily by changes in crystalline lens power.

Comparison of the experience sampling method and questionnaires to assess visual activities in pre-teen and adolescent children.

AIM: A study was conducted to assess the feasibility of the experience sampling method (ESM) to quantify the daily visual tasks of children. METHODS: Thirty-one children (9-14 years old, 39% male) were randomly paged after school (four times per day) and on weekends (eight times per day) for seven consecutive days. When paged, the children completed a voicemail survey regarding the nature, duration, working distance and type of visual correction worn during the activity. Responses of the subjects were grouped into 14 categories. Before beginning the paging, each child and one parent also reported, via survey, the number of hours and working distance for several visual activities. RESULTS: The usable (complete voicemail responses) response rate was 87.1%. The most commonly reported activity category was watching television (17.8%). Other common responses included distance activities (12.5%), reading/studying (12.2%) and sports/outdoor activities (12.0%). Of the total number of responses, 25% were near work activities (reading/studying, computer use, near hobbies and playing Game Boy). The mean working distance (+/-S.D.) reported was 40.4 +/- 36.9 cm for reading/studying, 232.9 +/- 127.1 cm for watching television, 354.7 +/- 345.8 cm for distance activities and 438.5 +/- 421.0 cm for sports/outdoor activities. When comparing the ESM to surveys, the only significant difference was for the amount of time estimated to be spent in talking/conversation (p < 0.0001). No differences were found for any of the near work activities. CONCLUSIONS: The ESM provides a feasible way to quantify daily near work tasks in children.

The relation between tear film tests in patients with dry eye disease.

PURPOSE: The purpose of this report was to investigate the relation between dry eye diagnostic tests. METHODS: Dry eye patients were enrolled to complete a clinical examination, including the following dry eye tests: a meibomian gland evaluation, tear meniscus height, fluorescein tear breakup time, fluorescein staining of the cornea, the Schirmer 1 test, the phenol red thread test, and rose bengal staining of the conjunctiva. Statistical analyses, including correlation coefficients, the Wilcoxon sign rank test, chi-square test, and logistic regression were used to address the relation between these clinical tests of dry eye. RESULTS: There was a strong relation between the Schirmer test and fluorescein staining in all four statistical analyses. Similarly, there was also a strong relation between the phenol red thread test and both fluorescein and rose bengal staining. Finally, the results of the Schirmer test were associated with the tear breakup time test in three of four analyses. CONCLUSIONS: The results indicate that tests of aqueous deficiency (volume or production) are associated with ocular surface desiccation. This important relation should be recognized when choosing dry eye tests as outcomes in clinical trials and epidemiological studies.