Do optical aberrations contribute to visual loss in strabismic amblyopia?

If aberrations contribute significantly to the decreased visual function of strabismic amblyopic eyes, one would predict that (1) the pupil size for optimum resolution should be smaller in the amblyopic than in the normal eyes, (2) increasing target contrast by a constant ratio should not compensate for defocus of an amblyopic eye, and (3) the contrast sensitivity of the amblyopic eye should improve when tested with a stimulus that bypasses the eye's optics. We tested these predictions, using contrast sensitivity techniques, and found no evidence that aberrations contribute to the amblyope's abnormality.