Prevalence of astigmatism in a paediatric population with malocclusions.

AIM The purpose of this study was to investigate the prevalence of astigmatism among a paediatric population. MATERIALS AND METHODS A total of 322 consecutive patients of the department of Orthodontics and Gnathology, Dental Clinic, University of L'Aquila, were enlisted for the study and 176 were selected according to the exclusion criteria. Pre- treatment diagnostic data, which included radiographic cephalometric and dental cast evaluation, were recorded and presence of astigmatism was assessed through an ophthalmological examination. Differences in the prevalence of astigmatism by sex and malocclusion were analysed by using the chi-square (Pearson's chi-square test) and Fisher's exact tests. RESULTS According to the sagittal malocclusion, patients were classified as Class I (N=122), Class II Division 1 (N=26), Class II Division 2 (N=9), or Class III (N=19); according to the transverse malocclusion patients were classified into cross-bite (N=39) and no cross-bite (N=137) groups; after ophthalmological examination astigmatism was detected in 32 patients (18.18%). Statistically significant correlations were found between astigmatism and cross-bite (p < 0.0001), while no associations were found with other malocclusions. No gender influence was found for astigmatism or malocclusion. DISCUSSION Few study investigated a possible relationship between the ocular and stomatognathic system, and no data are available in the scientific literature. A higher prevalence of astigmatism was found in patients with cross-bite: as expected no other significant association was found. The relationship between astigmatism and cross-bite could be either related to a specific skeletal pattern, which could induce visual alterations, or to the effect of abnormal visual input on the postural system, which could induce stomatognathic alterations. CONCLUSION The findings of the present study suggest a possible association between astigmatism and cross-bite, but future studies are needed to confirm and explain this observation.