McCourt M E, Jacobs G H
Vision Res. 1984;24(10):1261-6. doi: 10.1016/0042-6989(84)90180-9.
Retinoscopy and electrophysiological refraction were performed on 55 and 24 far-accommodated eyes of California ground squirrels (Spermophilus beecheyi), respectively. These two indices were highly correlated, revealing the eye of this animal to be roughly emmetropic (-0.25 to -0.13 D). Depth of focus was assessed by measuring the effect which defocusing produced on the spatial resolving power of 32 optic nerve fibers. Depth of focus of the ground squirrel eye for a pupil diameter of 2.5 mm is estimated to be +/- 1.6 D, but will increase rapidly for smaller pupils. Accommodation in eleven ground squirrels ranged from 2 to 6 D, with a mean value of 3.9 D.
分别对55只和24只处于远调节状态的加利福尼亚地松鼠（Spermophilus beecheyi）的眼睛进行了检影验光和电生理验光。这两个指标高度相关，表明该动物的眼睛大致为正视眼（-0.25至-0.13 D）。通过测量散焦对32条视神经纤维空间分辨能力的影响来评估焦深。对于瞳孔直径为2.5 mm的地松鼠眼睛，焦深估计为±1.6 D，但对于较小的瞳孔，焦深将迅速增加。11只地松鼠的调节范围为2至6 D，平均值为3.9 D。
