Optic flow generated by rigid surface patches can be decomposed into a small number of elementary motion types. In these experiments, we show that the human visual system can evaluate expansion, one of these motion types, metrically. Moreover, we show that the discrimination of rates of expansion are spatially local. Because the estimation of the focus of expansion is somewhat imprecise, this l...

Four questions concerning the use and perception of time to contact, tc, are identified. (i) Is tc information used in the timing of interceptive actions? (ii) If so, what control strategies are used? (iii) What are the perceptual sources of tc information and which of them do people use? (iv) How is the information extracted by the perceptual systems? Research relevant to these questions is re...

Congenital aplasia and hypoplasia of the optic nerves are rarely seen in human beings4 and an imak6 Similar conditions occur infrequently in but no detailed description of the condition has been given, except for the Bmn-wys strain of rat. Bmn-wys rats are animal models of inherited retinal degeneration; aplasia or hypoplasia of the optic nerve occurs in association with microphthalmosI0 in the...

An 81-year-old woman presented with light perception vision in her left eye and had pallid swelling of the left optic disk. Temporal artery biopsy was normal. Magnetic resonance imaging revealed enlargement and enhancement of the left orbital optic nerve. There were vitreous cells, but a vitrectomy specimen showed only a benign lymphocytic population. Her vision deteriorated to no light percept...

Imaging studies in typical glaucomatous cupping are usually needless. This article reviews the various clinical presentations for considering imaging in patients presenting with cupped disc.

In all of 100 consecutive patients referred for retinal angiography with a clinical diagnosis of probable or possible papilloedema a definite diagnosis was made from neurological assessment, neuroradiological investigations, and follow-up. The cases have been divided into 2 groups--those with proved papilloedema and those which have been called either normal or pseudopapilloedema. In all cases ...

The authors describe a case of nasal and macular retinoschisis in a patient with open angle glaucoma. A 75 year-old female with optic nerve head damage secondary to chronic open angle glaucoma developed macular schisis and a separate area of retinoschisis nasal to her optic disk. There were no other identifiable causes for her retinoschisis. Glaucoma related structural defects offer a plausible...

AIMS To compare monoscopic and stereoscopic assessment of the optic disc using novel software for the digital stereoscopic analysis of optic disc stereopairs. METHODS Software was developed for the stereoscopic display of digital optic disc images using an interlaced display method. Neuroretinal rim width was determined at 10 degree intervals around the optic disc using a custom (stereoscopic...