Monocular blur effects on normal vision have been found to mimic some aspects of spatial perception in anisometropic amblyopia (Barbeito, Bedell, Flom, & Simpson,
1987; Formankiewicz & Waugh,
2013; Levi & Klein,
1985,
1990; Song, Levi, & Pelli,
2014). For example, Levi and Klein (
1982a,
1982b) found the same relative differences in Vernier and grating acuities in anisometropic amblyopia as those found in normal vision but scaled to their level of amblyopic eye visual acuity. Therefore, if normal vision could be “scaled up,” for example, by using optical blur, spatial perception similar to anisometropic amblyopes may occur. Additionally, Barbeito et al. (
1987) found that reducing luminance levels (with neutral density filters) degraded optotype acuity of anisometropic amblyopic eyes and monocularly blurred normal eyes similarly. Formankiewicz and Waugh (
2013) recently reported that the ratio of visual acuity to the extent of crowding remains constant in monocularly blurred normals, and this result was confirmed in anisometropic amblyopes (Song et al.,
2014). Interestingly, a close relationship between this ratio and stereopsis, a binocular measure related to interocular suppression, was also noted. Song et al. (
2014) further suggested that blur is a good model for purely anisometropic amblyopia, which is mainly size limited, like normal central vision with added blur. Pianta and Kalloniatis (
1998) compared binocular suppression characteristics of monocularly blurred normals and anisometropic amblyopes using a reaction time paradigm for the detection of a 0.65° dichoptically flashed test disc across different luminance levels. Similar reaction times were measured for the two groups, indicating similarity of interocular suppression characteristics. Physiological evidence also shows that rearing animals with monocular blur under binocular viewing conditions leads to anisometropic amblyopia (Kiorpes, Kiper, O'Keefe, Cavanaugh, & Movshon,
1998; Maguire, Smith, Harwerth, & Crawford,
1982; E. L. Smith et al.,
1997; E. L. Smith, Harwerth, & Crawford,
1985).