Stereopsis and spatial perception in amblyopes and uncorrected ametropes.

Amblyopes and nonamblyopes were compared on 2 tests of spatial perception. One, the Titmus stereotest, provided only disparity cues and thus measured pure stereopsis. The other, the 3-rods test, provided a variety of monocular and binocular cues and measured the precision of distance discrimination. On both tests the amblyopes were significantly worse than nonamblyopes with equivalent acuity deficits. The Titmus stereotest was found to be an effective means of screening for amblyopia. The results of the distance discrimination test are discussed in terms of their clinical and physiological implications.