Stereothresholds during Voluntary Head Movement and Disconjugate Image Motion.

Significance: Stereothresholds increase in the presence of disconjugate image motion, whether this motion results from vergence errors that occur during active head movements or is imposed externally.

Purpose: During rapid voluntary oscillations of the head, vergence eye position has been reported to vary with a peak-to-peak amplitude of about 0.5°-a considerably greater amplitude than when the head is still.

Optical Rehabilitation of a Patient with Keratoconus and Nystagmus.

Keratoconus is a progressive corneal disease characterized by bilateral yet usually asymmetric thinning of the cornea with an onset typically in teenage years. While it often presents as an isolated condition, keratoconus may also be associated with many systemic and/or ocular diseases, such as connective tissue and chromosomal disorders. Its association with nystagmus has been described in Leber's congenital amaurosis, where patients also exhibit abnormal pupillary responses, early-onset retinal dystrophy, mental developmental delays, and eventual blindness.

Relationship between threshold and suprathreshold perception of position and stereoscopic depth.

We seek to determine the relationship between threshold and suprathreshold perception for position offset and stereoscopic depth perception under conditions that elevate their respective thresholds. Two threshold-elevating conditions were used: (1) increasing the interline gap and (2) dioptric blur. Although increasing the interline gap increases position (Vernier) offset and stereoscopic disparity thresholds substantially, the perception of suprathreshold position offset and stereoscopic depth remains unchanged.