RNFL measurements vary with the axial length/refractive error of the eye. Analysis of RNFL thickness in the evaluation of glaucoma should always be interpreted with reference to the refractive status. Although the normative database provided by OCT has been helpful in identifying ocular diseases involving the RNFL, it may not be reliable in the analysis of myopic eyes.

Aim: To study the prevalence, type, and progression of astigmatism in Chinese preschool children, and its effect on refractive development. Methods: A cross sectional study of preschool children was carried out in two randomly selected kindergartens. A cohort study was performed on a subset of children, five years after initial examination. Refractive error (measured by cycloplegic autorefraction) and axial ocular dimensions (measured by ultrasonography) were the main study outcomes. Results: 522 children participated in the study; the mean age was 55.7 months (SD 10.9; range 27 to 77). Mean cylinder reading was 20.65 D (SD 0.58; range 0.00 to 24.75), and with the rule astigmatism was predominant (53%). In the 108 children studied longitudinally, the mean cylinder reading reduced from 20.62 D to 20.50 D (p = 0.019). The presence of astigmatism in initial examination predisposed the eyes towards greater myopisation (p,0.001). In addition, children with increased astigmatism had greater myopic progression (p,0.001) and axial length growth (p = 0.002).Conclusions: This study reports a high prevalence of astigmatism in Chinese preschool children. The presence of astigmatism, and particularly with increasing astigmatism, appears to predispose the children to progressive myopia. Further studies are warranted.

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