Nandakumar Krithika, Leat Susan J
School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Optom Vis Sci. 2009 Mar;86(3):196-207. doi: 10.1097/OPX.0b013e318196cd93.
Among children and young people with Down syndrome (DS) there is a high prevalence of reduced accommodation. Prescribing bifocals for these patients has not become fully clinically accepted, although it would be anticipated to improve visual acuity (VA). The aim of this study is to investigate the impact of bifocal correction on VA, visual perceptual skills and early literacy development in children with DS who have reduced accommodation and who are provided with a bifocal correction. This paper describes the study design and the baseline optometric findings.
We have chosen a longitudinal design with frequent measures of subtests of performance to control for progression with time. The main outcome measures are early literacy and visual perception skills. Secondary outcomes are VA and accommodative function. These are measured at baseline, the participant followed for 6 months when bifocals are prescribed if necessary, and the participants were followed for another 6 months with bifocals.
Fourteen participants with DS aged 8 to 19 years were enrolled. At baseline 79% required a change in their distance spectacle prescription. One hundred percent had reduced accommodation both before and after new single vision glasses were prescribed. None had an adverse reaction to 0.5 or 1% Cyclopentolate. All the subjects were able to perform either a distance or near crowded Patti-pics symbols test and 93% were able to perform both. There was a significant improvement of near VA with the new single vision spectacles (p = 0.015). The mean binocular distance VA was 0.362 +/- 0.17 logMAR whereas binocular near VA was 0.489 +/- 0.235.
This study confirms previous findings of a high prevalence of reduced accommodation and shows that near VA is reduced compared to distance VA. The present results indicate that all subjects might benefit from bifocals.
在唐氏综合征（DS）儿童和青少年中，调节功能减退的患病率很高。尽管预计双焦点眼镜能提高视力（VA），但为这些患者开双焦点眼镜尚未在临床上完全被接受。本研究的目的是调查双焦点矫正对调节功能减退且佩戴双焦点矫正眼镜的DS儿童的视力、视觉感知技能和早期识字能力发展的影响。本文描述了研究设计和基线验光结果。
我们选择了纵向设计，通过频繁测量性能子测试来控制随时间的进展。主要结局指标是早期识字能力和视觉感知技能。次要结局指标是视力和调节功能。这些指标在基线时进行测量，必要时为参与者开具双焦点眼镜并随访6个月，之后再佩戴双焦点眼镜随访6个月。
招募了14名年龄在8至19岁的DS参与者。基线时，79%的人需要更换远用眼镜处方。在开具新的单焦点眼镜前后，100%的人调节功能减退。没有人对0.5%或1%的环喷托酯有不良反应。所有受试者都能够进行远用或近用拥挤的帕蒂图片符号测试，93%的人能够进行两种测试。新的单焦点眼镜使近视力有显著改善（p = 0.015）。双眼平均远视力为0.362 +/- 0.17 logMAR，而双眼近视力为0.489 +/- 0.235。
本研究证实了先前关于调节功能减退患病率高的发现，并表明近视力低于远视力。目前的结果表明，所有受试者可能都能从双焦点眼镜中受益。
