Of the 7599 children who completed the vision-testing session, 491 (6.5%) wore glasses frequently, and 185 (2.4%) wore glasses only occasionally. Fifty-seven (0.8%) children had a “large” angle of strabismus and 96 (1.3%) had a “small” angle. Some children (
n = 264; 3.5%) had received occlusion treatment for amblyopia.
Figure 1shows the overlaps between binary versions of these three vision outcomes in which frequent/occasional glasses wearers were grouped together as were children with large/small angles of strabismus. Of the 6815 children with usable victimization data, 2348 (34.5%) were overt victims. One hundred fifty-two children failed to make sufficient responses in the relational section of the interview to be classified. Of the remainder, 1106 (16.6%) were relational victims. Seven hundred sixteen children were victims of both overt and relational bullying.
Table 2shows the uncorrected prevalences of victimization due to either overt or relational according to each individual visual category: wearing glasses, strabismus, and having worn an eye patch and also according to number of defects. Unadjusted and adjusted odds ratios (ORs) are shown in
Table 3 . It can be seen that, in all visual categories and also for the number of defects, children are most often victims of overt as opposed to relational bullying. There is some evidence for an association between glasses-wearing and overt victimization (
P = 0.016) that is not substantially altered on adjustment for sex and socioeconomic status (
P = 0.017). Children wearing glasses were more likely to be victimized, with a larger effect for frequent (adjusted OR: 1.35; 95% CI: 1.09–1.69) than occasional (adjusted OR: 1.26; 95% CI: 0.86–1.84) glasses wearers. Similarly, there is some evidence for an association between the number of visual defects and overt victimization (
P = 0.006 both with and without adjustment), with children with defects being more likely to be victimized. However, no dose–response relationship was found, the effect size being larger for children with one defect than for those with two or more defects. This is probably due to the construction of the number of defects variable, which is dominated by glasses wearers and children who wore patches (see
Fig. 1 ). As an alternative to this approach, strabismus and patching were fitted separately in the model for overt victimization after correction for glasses-wearing. In neither case was the effect significant (
P = 0.421 and 0.576, respectively), nor was there any evidence for interactions between the vision defects in predicting overt victimization. Although the uncorrected association between wearing an eye patch and overt victimization was not significant at the 5% level, after adjustment it was (
P = 0.048), with patched children being more likely to be victims (adjusted OR: 1.37; 95% CI: 1.01–1.86).
No significant evidence was found at the 5% level for an association between strabismus and overt victimization or for any associations between the vision defect outcomes and either relational victimization or being a victim of both forms of bullying (P = 0.145). The analysis for strabismus was rerun with only large versus small/no strabismus as an alternative but there was still no statistically significant effect (P = 0.182). Similarly, no evidence was found for interactions between vision defects and sex in predicting overt victimization. The results were not altered after excluding 82 children identified with multiple disabilities from the models for overt victimization and 76 from the models for relational victimization.
In this age group, when bullying occurs, it is most likely to be overt bullying. However, because a considerable number of children (
n = 716) reported that they had experienced both overt and relational bullying, uncorrected prevalences of victimization are provided for orthogonal bullying groups in
Table 4 . It can be seen that, for those children who have experienced both types of bullying, there is no suggestion of an increase in bullying in line with more severe visual defects. The trends for those experiencing only overt or only relational are very similar to those in
Table 2 , which shows that the significant effects are due to differences in overt but not relational bullying. The logistic model was not repeated for the groups in
Table 4 , as adjustment in the previous model made little difference to the estimates.