Department of Applied Physics, Biomedical and X-Ray Physics, Royal Institute of Technology, Stockholm, Sweden.
Invest Ophthalmol Vis Sci. 2012 Oct 17;53(11):7176-82. doi: 10.1167/iovs.11-9034.
Animal studies suggest that the periphery of the eye plays a major role in emmetropization. It is also known that human myopes tend to have relative peripheral hyperopia compared to the foveal refraction. This study investigated peripheral sensitivity to defocus in human subjects, specifically whether myopes are less sensitive to negative than to positive defocus.
Sensitivity to defocus (logMAR/D) in the 20° nasal visual field was determined in 16 emmetropes (6 males and 10 females, mean spherical equivalent -0.03 ± 0.13 D, age 30 ± 10 years) and 16 myopes (3 males and 13 females, mean spherical equivalent -3.25 ± 2 D, age 25 ± 6 years) using the slope of through-focus low-contrast resolution (10%) acuity measurements. Peripheral wavefront measurements at the same angle were obtained from 13 of the myopes and 9 of the emmetropes, from which the objective depth of field was calculated by assessing the area under the modulation transfer function (MTF) with added defocus. The difference in depth of field between negative and positive defocus was taken as the asymmetry in depth of field.
Myopes were significantly less sensitive to negative than to positive defocus (median difference in sensitivity 0.06 logMAR/D, P = 0.023). This was not the case for emmetropes (median difference -0.01 logMAR/D, P = 0.382). The difference in sensitivity between positive and negative defocus was significantly larger for myopes compared to emmetropes (P = 0.031). The correlation between this difference in sensitivity and objective asymmetry in depth of field due to aberrations was significant for the whole group (R(2) = 0.18, P = 0.02) and stronger for myopes (R(2) = 0.8, P < 0.01).
We have shown that myopes, in general, are less sensitive to negative than to positive defocus, which can be linked to their aberrations. This finding is consistent with a previously proposed model of eye growth that is driven by the difference between tangential and radial peripheral blur.
动物研究表明，眼睛的周边在正视化过程中起着重要作用。已知人类近视者的周边远视相对于中心凹屈光而言往往相对较高。本研究调查了人类受试者对离焦的周边敏感性，特别是近视者对负离焦是否比对正离焦的敏感性更低。
使用通过焦点低对比度分辨率（10％）视力测量的斜率，在 16 名正视者（6 名男性和 10 名女性，等效球镜-0.03 ± 0.13 D，年龄 30 ± 10 岁）和 16 名近视者（3 名男性和 13 名女性，等效球镜-3.25 ± 2 D，年龄 25 ± 6 岁）中确定 20°鼻侧视野的离焦敏感性（logMAR/D）。从 13 名近视者和 9 名正视者中获得了相同角度的周边波前测量值，并通过评估调制传递函数（MTF）的面积来计算客观景深，从而在添加离焦后添加了调制传递函数（MTF）。将负离焦和正离焦之间的景深差异视为景深的不对称性。
近视者对负离焦的敏感性明显低于正离焦（敏感性差异的中位数为 0.06 logMAR/D，P = 0.023）。正视者则不然（敏感性差异中位数为-0.01 logMAR/D，P = 0.382）。与正视者相比，近视者的正负离焦之间的敏感性差异明显更大（P = 0.031）。整个组的这种敏感性差异与由于像差引起的客观景深不对称之间的相关性具有统计学意义（R²= 0.18，P = 0.02），并且近视者的相关性更强（R²= 0.8，P <0.01）。
我们已经表明，一般来说，近视者对负离焦的敏感性低于正离焦，这与他们的像差有关。这一发现与之前提出的眼球生长模型一致，该模型由切向和径向周边模糊之间的差异驱动。
