The treatment and diagnosis of keratoconus has progressed in recent years. The development of devices for measuring both the anterior and posterior cornea has enabled diagnosis of early-stage keratoconus. Moreover, advances in aberrometers have enabled analysis of corneal aberrations and intraocular aberrations individually. These advances have led to dramatic changes in the treatment of keratoconus. Various treatment options including corneal cross-linking to stop progression of keratoconus, intracorneal ring implantation, contact lens treatment, and keratoplasty are being evaluated while taking into consideration changes in visual optics.

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Responses to local light stimulation (LS), transcorneal electrical stimulation (TES), optic chiasm stimulation (OX), and suprachroidal-transretinal stimulation (STS) before and after tetrodotoxin intravitreal injection were analyzed with independent component analysis (ICA). The responses were imaged by ophthalmoscopes modified for consecutive near infrared imaging. Time and spatial information was obtained by obtaining the images before and after the stimulus. The time and spatial information consists of several responses with different origins and noises not related to the stimulus. We used spatial ICA to separate spatial components from compounded signals. ICA applied to the data from three anesthetized cats and comparisons with previous researches revealed that origin of response of LS and STS is hemodynamics in the outer retinal and that of TES and OX is blood flow in the retinal artery. Two independent components were found in ICA of TES and those were different in time and spatial characteristics.

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We measured the perceived depth defined by motion parallax and/or size cue to examine the interaction of depth information from these two cues. The test stimulus consisted of 320 white discs distributed in a virtual three-dimensional space randomly either in front of or behind a CRT display. In the motion parallax only condition, the positions of the discs were shifted according to a monocularly viewing observer's head position, which oscillated horizontally. In the size cue only condition, the sizes of the discs were graded according to their distances from an observer viewing the stimulus while standing still. The results showed that perceived depth was very limited in the motion parallax only and size cue only conditions, while much greater depth was perceived when the two cues were available simultaneously. It appears that depth information from these two cues are integrated in a nonlinear fashion.

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