Assessing the accommodation response after near visual tasks using different handheld electronic devices

ABSTRACT Purpose: To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Methods: Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0.25 m from the subject's eyes. Three measurements of accommodation response were monocularly acquired at stimulus vergences ranging from 0 to 4 D (1-D step). Results: No statistically significant differences were found in the accommodation responses among the conditions. A moderate but gradually increasing root mean square, coma-like aberration was found for every condition. Conversely, the spherical aberration decreased as stimulus vergences increased. These outcomes were identified in comparison to the one-to-one ideal accommodation response, implying that a certain lag value was present in all stimulus vergences different from 0 D. Conclusions: The results support the hypothesis that the difference between the ideal and real accommodation responses is mainly attributed to parameters associated with the accommodation process, such as the near visual acuity, depth of focus, pupil diameter, and wavefront aberrations. The wavefront aberrations were dependent on the 3-mm pupil size selected in this study. The accommoda tion response was not dependent on the electronic device employed in each condition, and it was mainly associated with young age and level of amplitude of accommodation of the subjects.

摘要
研究目的：评估使用平板电脑与智能手机进行短时间阅读后的眼调节反应，并借助哈特曼-夏克波前像差仪（Hartmann-Shack aberrometer），探究不同调节刺激屈光度下眼调节反应的潜在差异。
方法：本研究纳入18名健康受试者，其散光度数低于1屈光度（D）、矫正视力达20/20及以上，且眼科检查结果正常。分别在三种不同条件下采集眼调节反应：眼调节系统处于放松状态，以及分别使用平板电脑、智能手机进行10分钟的近距离阅读以施加视觉负荷，测试距离为受试者眼前0.25米。随后在调节刺激屈光度范围为0至4屈光度、步长为1屈光度的条件下，单眼采集3次调节反应数据。
结果：三种条件下的眼调节反应均未出现统计学显著性差异。各条件下均观察到中度的彗差样像差均方根值，且该值随调节刺激屈光度升高而逐渐增大；与之相反，球差随调节刺激屈光度升高而降低。将上述结果与一对一的理想调节反应对比后发现，除0屈光度以外的所有调节刺激条件下均存在一定程度的调节滞后量。
结论：本研究结果支持如下假说：理想调节反应与实际调节反应之间的差异主要源于与调节过程相关的参数，例如近视力、焦深、瞳孔直径及波前像差。本研究采用的3mm瞳孔直径下，波前像差具有依赖性。眼调节反应与实验所用电子设备类型无关，主要与受试者的年轻年龄及调节幅度水平相关。