Foveal

About: Foveal is a research topic. Over the lifetime, 2652 publications have been published within this topic receiving 94120 citations.

Optical Coherence Tomography Imaging of the Fovea in Retinopathy of Prematurity

Abstract: Background and objective To report foveal optical coherence tomography (OCT) findings in patients with a history of retinopathy of prematurity (ROP). Patients and methods In a case-control study, OCT imaging of the fovea was performed on mostly adult patients with a history of ROP and no significant macular pathology. The same OCT imaging was performed on control subjects who were born full-term. Results Fourteen eyes of 12 patients with ROP were studied. Mean age was 39 years and mean gestational age at birth was 28 weeks. Of the 11 eyes with no cataract or pseudophakia, median best-corrected visual acuity was 20/40. Three eyes with cataracts had visual acuities of 20/50, 20/60, and 20/100. OCT imaging showed that eyes in the ROP group had a relative loss of the foveal depression, increased macular thickness, and continuation of inner retinal layers within the fovea. Conclusion OCT imaging demonstrated abnormal foveal architecture in patients with a history of ROP, but most of these patients maintained good visual acuity.

Control of a Camera for Active Vision: Foveal Vision, Smooth Tracking and Saccade

Abstract: Several characteristics of the human oculomotor system have been suggested to be useful also for active vision mechanisms. Among others, foveal vision and a tracking scheme based on two different modes, called smooth pursuit and saccade have often been postulated or implemented. The purpose of this paper is to formulate a setup in which the benefit of implementing these schemes can be evaluated in a systematic manner, based on control considerations but incorporating image processing constraints. First, the advantage of using foveal vision is evaluated by computing the size of the foveal window which will allow tracking of the largest possible class of signals. By using linear optimal control theory, this problem can be formulated as a one-variable maximization. Second, foveal vision leads naturally to smooth pursuit, defined as the performance that can be achieved by the controller resulting in the optimal size of the foveal window. This controller is relatively simple (i.e., linear, time-invariant) as is to be expected for this control loop. Finally, when smooth pursuit fails a corrective action must be performed to re-center the target on the fovea. Recent results in linear optimal control, provide the necessary tools for addressing this challenging problem in a systematic manner.

Spectral domain-optical coherence tomography study of retinas with a normal foveal contour and thickness after retinal detachment surgery.

Abstract: Purpose:The purpose was to study the disruption of the inner segment (IS) and outer segment (OS) junction associated with suboptimal visual outcome after successful retinal detachment surgery with an otherwise normal foveal contour and thickness.Materials and Methods:A comparative study of 2 groups,

Invariant spatial context is learned but not retrieved in gaze-contingent tunnel-view search.

Abstract: Our visual brain is remarkable in extracting invariant properties from the noisy environment, guiding selection of where to look and what to identify. However, how the brain achieves this is still poorly understood. Here we explore interactions of local context and global structure in the long-term learning and retrieval of invariant display properties. Participants searched for a target among distractors, without knowing that some “old” configurations were presented repeatedly (randomly inserted among “new” configurations). We simulated tunnel vision, limiting the visible region around fixation. Robust facilitation of performance for old versus new contexts was observed when the visible region was large but not when it was small. However, once the display was made fully visible during the subsequent transfer phase, facilitation did become manifest. Furthermore, when participants were given a brief preview of the total display layout prior to tunnel view search with 2 items visible, facilitation was already obtained during the learning phase. The eye movement results revealed contextual facilitation to be coupled with changes of saccadic planning, characterized by slightly extended gaze durations but a reduced number of fixations and shortened scan paths for old displays. Taken together, our findings show that invariant spatial display properties can be acquired based on scarce, para-/foveal information, while their effective retrieval for search guidance requires the availability (even if brief) of a certain extent of peripheral information.