This study is unique in that it evaluates the impact of presenting visual impairment and refractive errors in an Asian population of adolescent school pupils.
Adolescents with myopia did not report a significantly different quality of life for both classifications of five refractive error groups or three groups in 2005 / 2006, except healthy adolescents with persistent myopia reported lower social functioning score than those with persistent emmetropia. Although myopic adolescents might have visual function impairments, practical difficulties associated with the wearing
86 and maintenance of optical corrective devices, restrictions on sport and profession opportunities, our study suggests that the perceived general HRQoL of them was not diminished compared to their non-myopic peers. The self-reported total and summary scores of children with myopia were similar to the school healthy samples in the USA (total 81.1, physical 85.6, psychosocial 78.7).(Varni, Burwinkle & Seid, 2006) These similarities could be attributed to the lower degree of disability of myopia because myopia is not associated with the considerable morbidity or mortality associated with adolescents with some cancer, cardiac, orthopaedic, rheumatic or diabetic conditions.(Varni, Burwinkle, Katz, et al., 2002; Varni, Seid & Kurtin, 2001) Much lower HRQoL scores were reported by the children with cancer (total 72.2, physical 71.8 and psychosocial 72.6) and chronically ill children (total 77.2, physical 77.4 and psychosocial 77.1).
Overall we found similar QoL scores for adolescents with and without refractive errors. Unlike cataract and glaucoma which usually require surgical intervention, refractive errors are corrected using spectacles or contact lenses. Thus, most people with refractive error have good vision and show no reduction in their QoL. Although an adult study suggested that high-myopic patients had poorer vision- related QoL compared to moderate and mild-myopic patients, this result was not observed in our study.(K. Rose, Harper, Tromans, et al., 2000) A possible explanation is that most complications associated with high myopia such as myopic macular degeneration, macular holes, retinal breaks and tears occur during the later years of life. In our study, there was a low prevalence of complications secondary to high myopia.
87 The prevalence of presenting visual impairment of > 0.3 LogMAR in the better-seeing eye amongst 1,249 adolescents with a mean age of 13.8 years was 5.7%.
Adolescents with impairment reported lower total, psychosocial, and school scores, as measured by the PedsQL v4. Thus, presenting BEVI was significantly associated with a decrement in their overall well-being although these differences are below the minimal clinically meaningful differences (Total: 4.36, Psychosocial: 5.30, School:
9.12) suggested by Varni et al.(Varni, Burwinkle, Seid & Skarr, 2003) The most common cause of low presenting visual impairment in our study, and in others, is under-corrected refractive errors but we found no association between refractive errors per se and QoL.
Nevertheless, presenting visual impairment may affect school learning, outdoor activity, and social life. This may compromise an adolescent’s school achievement and thus a lower school functioning score is reported. Our study also showed a deleterious effect on psychosocial functioning of adolescents with visual impairment. However, much lower PedsQL scores have been reported by children with cancer (total 72.2, physical 71.8, and psychosocial 72.6) and chronically ill children (total 77.2, physical 77.4, psychosocial 77.1).(Varni, Burwinkle, Katz, et al., 2002; Varni, Seid & Kurtin, 2001)
The concordance in QoL measures between adolescents with BEVI or refractive errors and their parent-proxy were small. The result of Bland-Altman plot also showed that there was considerable difference between scores reported by child and their parent-proxy, that is, difference ranges within 2-points on the Likert-scale.
The lack of correlation between the parent-proxy and child’s report may be due to differences in perception of the teenager’s HRQoL. Our study also suggested that
88 parents are able to rate more accurate the child’s HRQoL in relation to domains of physical functioning compared with less visible domains such as social or emotional functioning. These findings agree well with evidence from previous studies (Achenbach, McConaughy & Howell, 1987; Varni, Seid & Rode, 1999). Hence, parent-proxy report should be included to complement child-self report in paediatric populations with better eye presenting visual impairment or refractive errors.
Unlike the various instruments for the measurement of vision-related QoL in adults such as Vision-Related QoL Core Measure and NEI-VFQ-25, PedsQL v4 is a generic instrument, and thus may not be sensitive enough to detect subtle effects due to ocular conditions. Nevertheless, this well validated (Cronbach’s alphas reported were all > 0.70)) and widely used instrument has been used for comparisons of QoL in the paediatric population across a variety of medical conditions such as asthma, cancer, diabetes, epilepsy, inflammatory bowel disease, headaches, obesity, paediatric rheumatology, cardiology, orthopaedic and psychiatric condition, and thus was felt to be appropriate for the purpose of this study. (Bastiaansen, Koot, Bongers, et al., 2004;
Felder-Puig, Frey, Proksch, et al., 2004; Powers, Patton, Hommel & Hershey, 2003;
Upton, Eiser, Cheung, et al., 2005; Varni, Burwinkle, Katz, et al., 2002; Varni, Seid &
Kurtin, 2001) Furthermore, with its parallel parent-proxy report, we were allowed to investigate the relationship between child and parent-proxy ratings of their QoL.
Although the multiplicity of potential endpoints arises with PedsQL v4, as with other QoL instruments, we have focused on the total score as the principal endpoint and regarded the other scores as secondary to this. In addition, multiple statistical testing can create problems in the interpretation of the results and may inflate the number of statistically significant differences found. In our case, there was
89 a paucity of statistically significant differences (using the conventional p < 0.05) so this is likely to have little impact on the conclusions we draw.
The results of this study must be considered in light of the following limitations. The cross-sectional nature of the study limits the inferences relating to possible causal relationships. There is a possibility of reporting bias in self-reported medical conditions of the child because the condition was not assessed by health care professionals or substantiated by medical record reviews. Another limitation of our study is that the best corrected visual acuity was not assessed, and thus visual impairment due to uncorrected refractive error (differences of habitual and best- corrected visual acuity) cannot be determined. Other causes of visual impairment such as congenital glaucoma and cataract were also not assessed; however, these conditions are likely to be rare. Our study was also limited by the differences found in child’s age, gender and ethnicity between the respondents and non-respondent of the parent-proxy report. The samples were school-based rather than population-based.
As such, the generalisation of the findings to general paediatric population may be limited.
This study is the first Asian study to investigate the impact of presenting better-seeing eye visual impairment and refractive errors on HRQoL using the PedQoL v4 instrument in the paediatric population, and to evaluate the concordance between child self-report and parent proxy-report of QoL with a well validated measure. Other strengths of the study include the use of a standardised method (including cycloplegic refraction) in all three schools, a high participation rate of 80%
for the child self-report, 61% for the parent-proxy report. The use of PedQoL, which is a generic form for measurement of HRQoL, allows for direct comparisons between
90 children with visual impairment or refractive errors, and those with other childhood diseases or a healthy population. Research is required to replicate and refine this study to elaborate the needs of children with visual impairments. Longitudinal studies of HRQoL will be of interest to assist in evaluating the magnitude of change in HRQoL over time, with changes in the children’s vision and refractive status during key developmental transition periods such as development of myopia.
In summary, we show in this population of healthy adolescents that BEVI was statistically though not clinically associated with impaired total, psychosocial and school functioning QoL scores. Thus, there is a need to understand and address visual impairment at a young age. However, similar HRQoL scores were reported by adolescents with and without refractive errors.