The influence of age, refractive error, visual demand and lighting conditions on accommodative ability in Malay children and adults
Near work, accommodative inaccuracy and ambient lighting conditions have all been implicated in the development of myopia. However, differences in accommodative responses with age and refractive error under different visual conditions remain unclear. This study explores differences in accommodative ability and refractive error with exposure to differing ambient illumination and visual demands in Malay schoolchildren and adults.
Sixty young adults (21–25 years) and 60 schoolchildren (8–12 years) were recruited. Accommodative lag and accommodative fluctuations at far (6 m) and near (25 cm) were measured using the Grand Seiko WAM-5500 open-field autorefractor. The effects of mesopic room illumination on accommodation were also investigated.
Repeated-measures ANOVA indicated that accommodative lag at far and near differed significantly between schoolchildren and young adults [F(1.219, 35.354) = 11.857, p < 0.05]. Post hoc tests using the Bonferroni correction showed that at near, there was a greater lag in schoolchildren (0.486 ± 0.181 D) than young adults (0.259 ± 0.209 D, p < 0.05). Repeated-measures ANOVA also revealed that accommodative lag at near demands differed statistically between the non-myopic and myopic groups in young adults and schoolchildren [F(3.107, 31.431) = 12.187, p < 0.05]. Post hoc tests with Bonferroni correction showed that accommodative lag at near was significantly greater in myopic schoolchildren (0.655 ± 0.198 D) than in non-myopic schoolchildren (0.202 ± 0.141 D, p < 0.05) and myopic young adults (0.316 ± 0.172 D, p < 0.05), but no significant difference was found between myopic young adults (0.316 ± 0.172 D) and non-myopic young adults (0.242 ± 0.126 D, p > 0.05). Accommodative lag and fluctuations were greater under mesopic room conditions for all ages [all p < 0.05].
Greater accommodative lag was found in myopes than in emmetropes, in schoolchildren than in adults, and under mesopic conditions than under photopic conditions. Accommodative fluctuations were greatest in myopes and in mesopic conditions. These results suggest that differences exist in the amount of blur experienced by myopes and non-myopes at different ages and under different lighting conditions.
KeywordsAccommodation Myopia Lag of accommodation Illumination Children
Special thanks to Prof. Edward Mallen (University of Bradford, UK) and Saiful Azlan Rosli (iROViS, UiTM) for their technical assistance with Grand Seiko and lighting setup.
This study was financially supported through an E-Science Fund grant (06-01-01-SF0452) under the Ministry of Science, Technology and Innovation of Malaysia.
Compliance with ethical standards
All procedures in this research adhered to the ethical standards of the institutional research committee in accordance with the 1964 Helsinki declaration.
Informed consent was obtained from all participants and the legal guardians in the study.
Conflict of interest
None of the authors has any proprietary interests or conflicts of interest related to this submission.
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