ABSTRACT
Detection of refractive error in children is crucial to avoid amblyopia and its impact on quality of life. We here performed a retrospective study in order to develop prediction models for spherical and cylinder refraction in children. The enrolled 1221 eyes of 617 children were divided into three groups: the development group (710 eyes of 359 children), the validation group (385 eyes of 194 children), and the comparison group (126 eyes of 64 children). We determined noncycloplegic and cycloplegic refraction values by autorefractometry. In addition, several noncycloplegic parameters were assessed with the use of ocular biometry. On the basis of the information obtained from the development group, we developed prediction models for cycloplegic spherical and cylinder refraction in children with the use of stepwise multiple regression analysis. The prediction formulas were validated by their application to the validation group. The similarity of noncycloplegic and predicted refraction to cycloplegic refraction in individual eyes was evaluated in the comparison group. Application of the developed prediction models for spherical and cylinder refraction to the validation group revealed that predicted refraction was significantly correlated with measured values for cycloplegic spherical refraction (R = 0.961, P < 0.001) or cylinder refraction (R = 0.894, P < 0.001). Comparison of noncycloplegic, cycloplegic, and predicted refraction in the comparison group revealed that cycloplegic spherical refraction did not differ significantly from predicted refraction but was significantly different from noncycloplegic refraction, whereas cycloplegic cylinder refraction did not differ significantly from predicted or noncycloplegic values. Our prediction models based on ocular biometry provide estimates of refraction in children similar to measured cycloplegic spherical and cylinder refraction values without the application of cycloplegic eyedrops.
Subject(s)
Amblyopia , Mydriatics/administration & dosage , Quality of Life , Refractive Errors , Visual Acuity/drug effects , Amblyopia/diagnosis , Amblyopia/drug therapy , Amblyopia/physiopathology , Child , Child, Preschool , Female , Humans , Male , Refraction, Ocular , Refractive Errors/diagnosis , Refractive Errors/drug therapy , Refractive Errors/physiopathology , Retrospective Studies , Vision ScreeningABSTRACT
Purpose: To provide insight into the mechanism underlying corneal deformation in keratoconus, we examined the relations among corneal curvature, thickness, and volume as well as the association of corneal scar formation with these parameters. Methods: A total of 288 corneas of 174 keratoconus patients and 114 corneas of 57 control subjects were examined by anterior segment-optical coherence tomography (AS-OCT). Anterior and posterior refractive values, corneal thickness (CT), and corneal volume (CV) were determined by AS-OCT for both control and keratoconic eyes. The pattern of corneal stromal scarring was also determined from the AS-OCT images. Results: The distribution of CV was similar for keratoconic and control eyes, whereas anterior and posterior refractive values as well as CT showed a wider distribution for keratoconic eyes. The progression of corneal deformation initially occurred without corneal thinning but was later associated with a decrease in CT and an eventual loss of CV. The progression of scarring from the anterior to the posterior stroma was associated with an increase in anterior refractive value and decreases in posterior refractive value, CT, and CV. Conclusions: The progression of keratoconus as reflected by corneal deformation was associated with a reduction in CT and CV as well as stromal scar formation. The loss of CV occurred after the initial decline in CT, suggesting that stromal degradation occurred only at the advanced stage of keratoconus.
