D(max) for stereoscopic depth perception with simulated monovision correction.

PURPOSE: Persons who wear monovision correction typically receive a clear image in one eye and a blurred image in the other eye. Although monovision is known to elevate the minimum stereoscopic threshold (Dmin), it is uncertain how it influences the largest binocular disparity for which the direction of depth can reliably be perceived (Dmax). In this study, we compared Dmax for stereo when one eye's image is blurred to Dmax when both eyes' images are either clear or blurred.
METHODS: The stimulus was a pair of vertically oriented, random-line patterns. To simulate monovision correction with +1.5 or +2.5 D defocus, the images of the line patterns presented to one eye were spatially low-pass filtered while the patterns presented to the other eye remained unfiltered.
RESULTS: Compared to binocular viewing without blur, Dmin is elevated substantially more in the presence of monocular than binocular simulated blur. Dmax is reduced in the presence of simulated monocular blur by between 13 and 44%, compared to when the images in both eyes are clear. In contrast, when the targets presented to both eyes are blurred equally, Dmax either is unchanged or increases slightly, compared to the values measured with no blur.
CONCLUSION: In conjunction with the elevation of Dmin, the reduction of Dmax with monocular blur indicates that the range of useful stereoscopic depth perception is likely to be compressed in patients who wear monovision corrections.