In this study we examined the effects of simulated horizontal and vertical viewpoint jitter on the vection and postural sway induced by radial patterns of optic flow. During each trial, observers were exposed sequentially to 20 s periods of radially expanding flow, radially contracting flow, and static visual scenes. For half the trials, simulated viewpoint jitter was added to the radially expa...

Previously, we have shown that humans with amblyopia exhibit deficits for global motion discrimination that cannot be simply ascribed to a reduction in visibility or contrast sensitivity. Deficits exist in the processing of global motion in the fronto-parallel plane that suggest reduced extra-striate function (i.e., MT) in amblyopia. Here, we ask whether such a deficit also exists for rotation ...

BACKGROUND Randomized controlled trials in research settings have demonstrated the efficacy of percutaneous radiofrequency neurotomy of the medial branches of the cervical dorsal rami in the palliation of chronic zygapophysial joint pain, a common cause of chronic neck pain, but one that is under-recognized in some quarters. AIMS This study aimed to determine the outcomes of radiofrequency ne...

C entral retinal vein occlusion (CRVO) is second only to diabetic retinopathy as a vascular cause of vision loss.1 Visual morbidity and blindness are most commonly due to macular capillary nonperfusion and persistent macular edema, as well as macular hemorrhage, vitreous hemorrhage, retinal detachment, and neovascular glaucoma.1,2 As the precipitating event in CRVO is thought to be intravascula...

PURPOSE Amblyopic observers show deficits for global motion discrimination that cannot be accounted for by their contrast sensitivity impairment. The processing of first- and second-order translational global motion is deficient, as is the processing of first-order optic flow, suggesting that cortical function in extrastriate areas is impaired. The authors sought to determine whether amblyopes ...

Basic research on the visual control of locomotion has focused on optic flow rules that connect specific features of the optic flow field (e.g., global radial outflow, tau, and splay rate) with specific actions (aiming, braking, and alignment with a path, respectively). There is growing recognition that, while optic flow rules are important, visual control of vehicles involves much more, includ...

A fast and switchable electro-optic radial polarization retarder (EO-RPR) fabricated using the electro-optic ceramic Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) is presented. This EO-RPR is useful for fast and switchable generation of a pure cylindrical vector beam. When used together with a pair of half-wave plates, the EO-RPR can change circularly polarized light into any cylindrical vector beam of inter...

A technique for accurate measurement of the principle refractive indices and birefringence for silklike samples is presented. It is based on rotating the linear polarization of the illuminating light on a silk immersed in reference liquid to achieve index matching at the silk/liquid interface. The technique was used to measure the principal refractive indices of a P. eburnus radial silk at diff...