Ostrin Lisa, Kasthurirangan Sanjeev, Win-Hall Dorothy, Glasser Adrian
University of Houston College of Optometry, Houston, Texas 77004, USA.
Optom Vis Sci. 2006 Sep;83(9):657-65. doi: 10.1097/01.opx.0000232810.61191.02.
Accommodation is a dioptric change in power of the crystalline lens resulting from ciliary muscle contraction that leads to an increase in lens surface curvatures and thickness and changes in the position of lens surfaces. Previous studies have used A-scan ultrasound to measure changes in the position of lens surfaces with voluntary accommodation, but have not simultaneously measured the change in refraction. The goal of this study is to simultaneously measure and correlate refractive and biometric changes in the lens during voluntary accommodation in humans.
Refraction was measured off-axis in the right eye and biometry on-axis in the left eye simultaneously during voluntary accommodation in 22 human subjects between the ages of 21 and 30 years (mean +/- standard deviation: 25.8 +/- 2.3 years). Subjects viewed a distant target and four near targets spanning the full accommodative range available to evaluate refraction and lens surface position at each accommodative state.
Maximum objectively measured accommodative amplitude of all subjects was 5.64 +/- 0.21 D (mean +/- standard error of mean). Biometric and refractive changes during accommodation were linearly correlated. The mean +/- standard error of mean decrease in anterior chamber depth was 0.051 +/- 0.008 mm/D, increase in lens thickness was 0.067 +/- 0.008 mm/D, and increase in anterior segment length was 0.017 +/- 0.005 mm/D during accommodation. There was a net anterior movement of the lens center of 0.017 +/- 0.005 mm/D.
Anterior chamber depth, lens thickness, and anterior segment length change linearly with refraction during accommodation. Per-diopter changes in the lens were greater in the current study compared with previous studies in which only accommodative demand was measured, which overestimates the accommodative response.
调节是由睫状肌收缩引起的晶状体屈光力的屈光度变化，导致晶状体表面曲率和厚度增加以及晶状体表面位置改变。先前的研究使用A超测量了晶状体表面位置随自主调节的变化，但未同时测量屈光变化。本研究的目的是在人类自主调节过程中同时测量晶状体的屈光和生物测量变化，并建立两者之间的关联。
在22名年龄在21至30岁之间（平均±标准差：25.8±2.3岁）的人类受试者自主调节过程中，同时测量右眼的离轴屈光和左眼的同轴生物测量。受试者观察一个远处目标和四个近目标，这些目标涵盖了整个可用的调节范围，以评估每个调节状态下的屈光和晶状体表面位置。
所有受试者的最大客观测量调节幅度为5.64±0.21 D（平均±平均标准误差）。调节过程中的生物测量和屈光变化呈线性相关。调节过程中，前房深度平均±平均标准误差减少0.051±0.008 mm/D，晶状体厚度增加0.067±0.008 mm/D，前段长度增加0.017±0.005 mm/D。晶状体中心有0.017±0.005 mm/D的净向前移动。
调节过程中，前房深度、晶状体厚度和前段长度随屈光呈线性变化。与之前仅测量调节需求的研究相比，本研究中晶状体每屈光度的变化更大，之前的研究高估了调节反应。
