The amount of light coming to the eye from an object depends on the amount of light striking the surface, and on the proportion of light that is reflected. If a visual system only made a single measurement of luminance, acting as a pho-tometer, then there would be no way to distinguish a white surface in dim light from a black surface in bright light. Yet humans can usually do so, and this skil...

Intractable diplopia occurs in approximately 0.8% of patients following strabis-mus surgery, with considerable detriment to visual quality of life. Long-term therapeutic occlusion is required to permit functional vision. Black intraocular lens (IOL) implantation is an effective therapeutic option associated with high rates of postoperative satisfaction. 1 Black IOL implantation entails a cost t...

BACKGROUND Complete blindness generally results in the loss of synchronization of circadian rhythms to the 24-hour day and in recurrent insomnia. However, some blind patients maintain circadian entrainment. We undertook this study to determine whether some blind patients' eyes convey sufficient photic information to entrain the hypothalamic circadian pacemaker and suppress melatonin secretion, ...

PURPOSE To assess visual task performance in three blind subjects implanted with epiretinal prostheses. DESIGN Prospective, investigational device exemption trial. METHODS Three subjects with light perception or no light perception vision were enrolled at a single center. All subjects had retinitis pigmentosa (RP). Main inclusion criteria: light perception or worse vision in one eye and som...

Illumination of only a few key points on a moving human body or face is enough to convey a compelling perception of human motion. A full understanding of the perception of biological motion from point-light displays requires accurate comparison with the perception of motion in normal, fully illuminated versions of the same images. Traditionally, these two types of stimuli (point-light and fully...

In etiolated seedlings, phytochrome A (phyA) mediates very-low-fluence responses (VLFRs), which initiate de-etiolation at the interphase between the soil and above-ground environments, and high-irradiance responses (HIR), which complete de-etiolation under dense canopies and require more sustained activation with far-red light. Light-activated phyA is transported to the nucleus by FAR-RED ELONG...