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Aim: Diabetic retinopathy (DR) and glaucoma are two most common retinal disorders that are major causes of blindness in diabetic patients. DR caused in retinal images due to the damage in retinal blood vessels, which leads to the formation of hemorrhages spread over the entire region of retina. Glaucoma is caused due to hypertension in diabetic patients. Both DR and glaucoma affects the vision loss in diabetic patients. Hence, a computer aided development of diagnosis system for Diabetic retinopathy and Glaucoma screening is proposed in this paper to prevent vision loss. Method: The diagnosis system of DR consists of two stages namely detection and segmentation of fovea and hemorrhages. The diagnosis system of glaucoma screening consists of three stages namely blood vessel segmentation, Extraction of optic disc (OD) and optic cup (OC) region and determination of rim area between OD and OC. Results: The specificity and accuracy for hemorrhages detection is found to be 98.47% and 98.09% respectively. The accuracy for OD detection is found to be 99.3%. This outperforms state-of-the-art methods. Conclusion: In this paper, the diagnosis system is developed to classify the DR and glaucoma screening in to mild, moderate and severe respectively.

Evidence is strong that the visual pathway is segregated into two distinct streams – ventral and dorsal. Two proposals theorize that the pathways are segregated in function: The ventral stream processes information about object identity, whereas the dorsal stream, according to one model, processes information about either object location, and according to another, is responsible in executing movements under visual control. The models are influential; however recent experimental evidence challenges them, e.gs. the ventral stream is not solely responsible for object recognition; conversely, its function is not strictly limited to object vision; the dorsal stream is not responsible by itself for spatial vision or visuomotor control; conversely, its function extends beyond vision or visuomotor control. In their place, we suggest a robust dichotomy consisting of a ventral stream selectively sampling high-resolution/focal spaces, and a dorsal stream sampling nearly all of space with reduced foveal bias. The proposal hews closely to the theme of embodied cognition: Function arises as a consequence of an extant sensory underpinning. A continuous, not sharp, segregation based on function emerges, and carries with it an undercurrent of an exploitation-exploration dichotomy. Under this interpretation, cells of the ventral stream, which individually have more punctate receptive fields that generally include the fovea or parafovea, provide detailed information about object shapes and features and lead to the systematic exploitation of said information; cells of the dorsal stream, which individually have large receptive fields, contribute to visuospatial perception, provide information about the presence/absence of salient objects and their locations for novel exploration and subsequent exploitation by the ventral stream or, under certain conditions, the dorsal stream. We leverage the dichotomy to unify neuropsychological cases under a common umbrella, account for the increased prevalence of multisensory integration in the dorsal stream under a Bayesian framework, predict conditions under which object recognition utilizes the ventral or dorsal stream, and explain why cells of the dorsal stream drive sensorimotor control and motion processing and have poorer feature selectivity. Finally, the model speculates on a dynamic interaction between the two streams that underscores a unified, seamless perception. Existing theories are subsumed under our proposal.

Purpose The deep component of the distal radioulnar ligament provides translational stability and rotational guidance to the forearm. However, controversy exists regarding the importance of this structure as well as the nature of its attachment to the distal ulna. We aimed to evaluate the topographic anatomy of the distal ulna attachment of both the superficial and the deep components of the radioulnar ligament and to assess the relationship between its internal and its external morphometry. Methods Thirteen human distal ulnae attached by ulnar part of the distal radioulnar ligament were scanned using micro–computed tomography and reconstructed in 3 dimensions. In addition, the distal radioulnar ligaments were examined under polarized light microscopy to determine the histological characteristics of collagen contained within the ligaments. Results The deep limbs have broad marginal insertions at the fovea, whereas the superficial limbs have a circular and condensed insertion to the ulnar styloid. The center of the deep limb was separated from the base of the ulnar styloid by a mean of 2.0 ± 0.76 mm, and this distance was positively correlated with the width of the ulnar styloid. The mean distance between the center of the ulnar head and the center of the fovea was 2.4 ± 0.58 mm. The proportion of collagen type I was lower in the deep limb than in the superficial limb. Conclusions This new observation of the footprint of the radioulnar ligament in the distal ulna indicates that the deep limb may serve as an internal capsular ligament of the distal radioulnar joint, whereas the superficial limb as the external ligament. Clinical relevance Knowledge of the topographic anatomy of the radioulnar ligament’s attachment to the distal ulna may provide a better understanding of distal radioulnar ligament–related pathologies. [ABSTRACT FROM AUTHOR]

Large individual differences in cone densities occur even in healthy, young adults with low refractive error. We investigated whether cone density follows a simple model that some individuals have more cones, or whether individuals differ in both number and distribution of cones. We quantified cones in the eyes of 36 healthy young adults with low refractive error using a custom adaptive optics scanning laser ophthalmoscope. The average cone density in the temporal meridian was, for the mean±SD, 43,216±6039, 27,466±3496, 14,996±1563, and 12,207±1278cones/mm2 for 270, 630, 1480, and 2070μm from the foveal center. Cone densities at 630μm retinal eccentricity were uncorrelated to those at 2070μm, ruling out models with a constant or proportional relation of cone density to eccentricity. Subjects with high central macula cone densities had low peripheral cone densities. The cone density ratio (2070:630μm) was negatively correlated with cone density at 630μm, consistent with variations in the proportion of peripheral cones migrating towards the center. We modelled the total cones within a central radius of 7deg, using the temporal data and our published cone densities for temporal, nasal, superior, and inferior meridians. We computed an average of 221,000 cones. The coefficient of variation was 0.0767 for total cones, but higher for samples near the fovea. Individual differences occur both in total cones and other developmental factors related to cone distribution. [ABSTRACT FROM AUTHOR]

Fixational eye movements ( FEMs), including microsaccades, drift, and tremor, shift our eye position during ocular fixation, producing retinal motion that is thought to help visibility by counteracting neural adaptation to unchanging stimulation. Yet, how each FEM type influences this process is still debated. Recent studies found little to no relationship between microsaccades and visual perception of spatial frequencies ( SF). However, these conclusions were based on coarse analyses that make it hard to appreciate the actual effects of microsaccades on target visibility as a function of SF. Thus, how microsaccades contribute to the visibility of stimuli of different SFs remains unclear. Here, we asked how the visibility of targets of various SFs changed over time, in relationship with concurrent microsaccade production. Participants continuously reported on changes in target visibility, allowing us to time-lock ongoing changes in microsaccade parameters to perceptual transitions in visibility. Microsaccades restored/increased the visibility of low SF targets more efficiently than that of high SF targets. Yet, microsaccade rates rose before periods of increased visibility, and dropped before periods of diminished visibility, for all the SFs tested, suggesting that microsaccades boosted target visibility across a wide range of SFs. Our data also indicate that visual stimuli fade/become harder to see less often in the presence of microsaccades. In addition, larger microsaccades restored/increased target visibility more effectively than smaller microsaccades. These combined results support the proposal that microsaccades enhance visibility across a broad variety of SFs. [ABSTRACT FROM AUTHOR]

Purpose To describe the grey fovea sign of fovea-involving macular oedema or subretinal fluid accumulation in red-free fundus photography. Methods A test set of 91 digital fundus photographs of good quality from 100 consecutive eyes in 72 patients with diabetic retinopathy or central serous chorioretinopathy was composed by one of the investigators and evaluated by four masked observers. The photographs were graded as to whether a normal dark fovea was present or absent. The reference method was foveal thickness measurement using optical coherence tomography ( OCT). Results Eyes graded as having a grey fovea on fundus photographs ( n = 67) had a median foveal thickness of 279 μm (interquartile range 130 μm), whereas eyes graded as having a normal dark fovea ( n = 24) had a median foveal thickness of 238 μm (interquartile range 44.5 μm, p = 0.025). Conclusion The absence of a dark fovea on red-free greyscale fundus photographs is a sign of foveal thickening or detachment that can be reliably recognized by graders when using OCT as the reference diagnostic method. Awareness of the grey fovea sign may facilitate fundus photographic screening for maculopathy because its absence is a reliable sign that no foveal oedema or detachment is present. Its presence may indicate that such conditions are present, but it can also be induced by various other conditions, for which reason it should prompt further investigations by OCT. [ABSTRACT FROM AUTHOR]

Adaptive optics (AO) imaging tools enable direct visualization of the cone photoreceptor mosaic, which facilitates quantitative measurements such as cone density. However, in many individuals, low image quality or excessive eye movements precludes making such measures. As foveal cone specialization is associated with both increased density and outer segment (OS) elongation, we sought to examine whether OS length could be used as a surrogate measure of foveal cone density. The retinas of 43 subjects (23 normal and 20 albinism; aged 6–67 years) were examined. Peak foveal cone density was measured using confocal adaptive optics scanning light ophthalmoscopy (AOSLO), and OS length was measured using optical coherence tomography (OCT) and longitudinal reflectivity profile-based approach. Peak cone density ranged from 29,200 to 214,000 cones/mm 2 (111,700 ± 46,300 cones/mm 2 ); OS length ranged from 26.3 to 54.5 μm (40.5 ± 7.7 μm). Density was significantly correlated with OS length in albinism (p < 0.0001), but not normals (p = 0.99). A cubic model of density as a function of OS length was created based on histology and optimized to fit the albinism data. The model includes triangular cone packing, a cylindrical OS with a fixed volume of 136.6 μm 3 , and a ratio of OS to inner segment width that increased linearly with increasing OS length (R 2 = 0.72). Normal subjects showed no apparent relationship between cone density and OS length. In the absence of adequate AOSLO imagery, OS length may be used to estimate cone density in patients with albinism. Whether this relationship exists in other patient populations with foveal hypoplasia (e.g., premature birth, aniridia, isolated foveal hypoplasia) remains to be seen. [ABSTRACT FROM AUTHOR]

Blue cone monochromacy (BCM) is a rare X-linked retinal disease characterized by the absence of L- and M-opsin in cone photoreceptors, considered a potential gene therapy candidate. However, most experimental ocular gene therapies utilize subretinal vector injection which would pose a risk to the fragile central retinal structure of BCM patients. Here we describe the use of ADVM-062, a vector optimized for cone-specific expression of human L-opsin and administered using a single intravitreal (IVT) injection. Pharmacological activity of ADVM-062 was established in gerbils, whose cone-rich retina naturally lacks L-opsin. A single IVT administration dose of ADVM-062 effectively transduced gerbil cone photoreceptors and produced a de novo response to long-wavelength stimuli. To identify potential first-in-human doses we evaluated ADVM-062 in non-human primates. Cone-specific expression of ADVM-062 in primates was confirmed using ADVM-062.myc, a vector engineered with the same regulatory elements as ADVM-062. Enumeration of human OPN1LW.myc-positive cones demonstrated that doses ≥3 × 10 10 vg/eye resulted in transduction of 18%-85% of foveal cones. A Good Laboratory Practice (GLP) toxicology study established that IVT administration of ADVM-062 was well tolerated at doses that could potentially achieve clinically meaningful effect, thus supporting the potential of ADVM-062 as a one-time IVT gene therapy for BCM., Competing Interests: Declaration of interests K.H., D.C., J.N., C.D., P.S., K.O.B., M.R., B.S., C.M.G., B.E.R., and R.N.G. are current or previous employees of Adverum Biotechnologies and hold stock grants. J.V.H. is a paid consultant of Adverum Biotechnologies., (Copyright © 2023 Adverum Biotechnologies Inc. Published by Elsevier Inc. All rights reserved.)

Background: Fovea plana is defined as an immature macula diagnosed by OCT, showing the unusual shunt of the inner retinal layers into the fovea. The incidence of fovea plana in the adult population remains to be determined. The aim of this study was to determine the incidence of fovea plana in the French population with age-related cataract., Methods: Consecutive patients who underwent cataract surgery in Rothschild Foundation Hospital, France, between January and March 2021, with preoperative analyzable OCT scans available, were retrospectively screened in order to determine the incidence of fovea plana in these population. Ophthalmological characteristics of patients were reported, and detailed., Result: Fovea plana was encountered in 20 out of 204 patients during the 3 months corresponding to an incidence of 9.8%. One of those patients had stage 2 fovea plana., Conclusion: Although fovea plana is defined as an immature macula, it is not rare in preoperative population. This macular aspect was not associated with poor visual acuity in our cohort.

Background: RS3PE (remitting seronegative symmetrical synovitis with edema and pitting) is a rare entity of unknown etiology that has been related to genetic predisposition due to the presence of HLA-A2 in 50% of cases and less frequently HLA-B7. Its pathogenesis is unknown, but it has been related to growth factors, and some mediators (TNF, IL-6). It is common in elderly people and the course of this illness presents with acute symmetrical polyarthritis, accompanied by edema in hands and feet. The diagnosis requires a high index of suspicion and to differentiate it from other entities such as rheumatoid arthritis, complex regional pain syndrome, rheumatic polymyalgia, in addition to ruling out malignant neoplasms, since there are many reports of its association with both solid and hematological neoplasms, being of bad prognosis when there is association. When there is no association with cancer, it responds well to the use of low doses of steroids and its prognosis is usually favorable., Clinical Case: 80-year-old woman with an acute onset with polyarthralgia, functional limitation associated with pitting edema in hands and feet. After approaching the patient and ruling out associated neoplasms, it was diagnosed RS3PE. It was managed with prednisone, observing a good response, with remission of the manifestations at 6 weeks and subsequent suspension of the steroid., Conclusions: RS3PE is a rare entity, and a high index of suspicion is required for the diagnosis. A complete approach is important to rule out cancer in patients affected with this syndrome. Prednisone continues to be the best therapeutic option., (© 2023 Revista Médica del Instituto Mexicano del Seguro Social.)

Evidence is strong that the visual pathway is segregated into two distinct streams-ventral and dorsal. Two proposals theorize that the pathways are segregated in function: The ventral stream processes information about object identity, whereas the dorsal stream, according to one model, processes information about either object location, and according to another, is responsible in executing movements under visual control. The models are influential; however recent experimental evidence challenges them, e.g., the ventral stream is not solely responsible for object recognition; conversely, its function is not strictly limited to object vision; the dorsal stream is not responsible by itself for spatial vision or visuomotor control; conversely, its function extends beyond vision or visuomotor control. In their place, we suggest a robust dichotomy consisting of a ventral stream selectively sampling high-resolution/focal spaces, and a dorsal stream sampling nearly all of space with reduced foveal bias. The proposal hews closely to the theme of embodied cognition: Function arises as a consequence of an extant sensory underpinning. A continuous, not sharp, segregation based on function emerges, and carries with it an undercurrent of an exploitation-exploration dichotomy. Under this interpretation, cells of the ventral stream, which individually have more punctate receptive fields that generally include the fovea or parafovea, provide detailed information about object shapes and features and lead to the systematic exploitation of said information; cells of the dorsal stream, which individually have large receptive fields, contribute to visuospatial perception, provide information about the presence/absence of salient objects and their locations for novel exploration and subsequent exploitation by the ventral stream or, under certain conditions, the dorsal stream. We leverage the dichotomy to unify neuropsychological cases under a common umbrella, account for the increased prevalence of multisensory integration in the dorsal stream under a Bayesian framework, predict conditions under which object recognition utilizes the ventral or dorsal stream, and explain why cells of the dorsal stream drive sensorimotor control and motion processing and have poorer feature selectivity. Finally, the model speculates on a dynamic interaction between the two streams that underscores a unified, seamless perception. Existing theories are subsumed under our proposal. [ABSTRACT FROM AUTHOR]

Aim: Diabetic Retinopathy (DR) is one of the major problems of diabetic patients. The diabetic patient is not aware of any symptom until it is too late for effective treatment. It is the leading cause of blindness. Diabetic retinopathy results in retinal disorders that include Microaneurysms (MA), soft exudates, hard exudates and intra-retinal vascular abnormalities. Methods: Soft Computing Neural Networks are used to detect and diagnose lesions or abnormalities associated with diabetic retinopathy which facilitate the Ophthalmologists in accurate diagnosis and early treatment to prevent vision loss in diabetic patients. Results: The result shows that the methodology used is well suited for the early diagnosis of the diabetic retinopathy disease. Conclusions: By evaluating the exudates and fovea region, and analyzing the relation between them, the severity of DR can be easily identified to prevent vision loss in diabetic patients.

The fovea is one of the most studied retinal specializations in vertebrates, which consists of an invagination of the retinal tissue with high packing of cone photoreceptors, leading to high visual resolution. Between species, foveae differ morphologically in the depth and width of the foveal pit and the steepness of the foveal walls, which could influence visual perception. However, there is no standardized methodology to measure the contour of the foveal pit across species. We present here FOVEA, a program for the quantification of foveal parameters (width, depth, slope of foveal pit) using images from histological cross-sections or optical coherence tomography (OCT). FOVEA is based on a new algorithm to detect the inner retina contour based on the color variation of the image. We evaluated FOVEA by comparing the fovea morphology of two Passerine birds based on histological cross-sections and its performance with data from previously published OCT images. FOVEA detected differences between species and its output was not significantly different from previous estimates using OCT software. FOVEA can be used for comparative studies to better understand the evolution of the fovea morphology in vertebrates as well as for diagnostic purposes in veterinary pathology. FOVEA is freely available for academic use and can be downloaded at: http://estebanfj.bio.purdue.edu/fovea.

Currently, medical image processing draws intense interests of scien- tists and physicians to aid in clinical diagnosis. The retinal Fundus image is widely used in the diagnosis and treatment of various eye diseases such as Diabetic Retinopathy, glaucoma etc. If these diseases are detected and treated early, many of the visual losses can be pre- vented. This paper presents the methods to detect main features of Fundus images such as optic disk, fovea, exudates and blood vessels. To determine the optic Disk and its centre we find the brightest part of the Fundus. The candidate region of fovea is defined an area circle. The detection of fovea is done by using its spatial relationship with optic disk. Exudates are found using their high grey level variation and their contours are determined by means of morphological recon- struction techniques. The blood vessels are highlighted using bottom hat transform and morphological dilation after edge detection. All the enhanced features are then combined in the Fundus image for the detection of abnormalities in eye.

The macula, as the central part of the retina, plays an important role in the reading process. However, its morphology has not been previously studied in the context of dyslexia. In this research, we compared the thickness of the fovea, parafovea and perifovea between dyslexic subjects and normal controls, in 11 retinal segmentations obtained by optical coherence tomography (OCT). With this aim, we considered the nine sectors of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid and also summarized data from sectors into inner ring subfield (parafovea) and outer ring subfield (perifovea). The thickness in all the four parafoveal sectors was significantly thicker in the complete retina, inner retina and middle retina of both eyes in the dyslexic group, as well as other macular sectors (fovea and perifovea) in the inner nuclear layer (INL), inner plexiform layer (IPL), IPL + INL and outer plexiform layer + outer nuclear layer (OPL + ONL). Additionally, the inner ring subfield (parafovea), but not the outer ring subfield (perifovea), was thicker in the complete retina, inner retina, middle retina (INL + OPL + ONL), OPL + ONL, IPL + INL and INL in the dyslexic group for both eyes. In contrast, no differences were found between the groups in any of the sectors or subfields of the outer retina, retinal nerve fiber layer, ganglion cell layer or ganglion cell complex in any eye. Thus, we conclude from this exploratory research that the macular morphology differs between dyslexic and normal control subjects, as measured by OCT, especially in the parafovea at middle retinal segmentations.

The relationship of macular pigments and foveal anatomy to the perception of Maxwell's spot (MS) and Haidinger's brushes (HB) entoptic phenomena were investigated. Dual-wavelength-autofluorescence and OCT were used to define macular pigment density and foveal anatomy in 52 eyes. MS was generated by alternating unpolarized red/blue and red/green uniform field illumination. HB was generated by alternating the linear polarization axis of a uniform blue field. In Experiment 1, horizontal widths of MS and HB were measured using a micrometer system and compared with macular pigment densities and OCT-defined morphometry. MS radius (mean 1.4°) was significantly less than HB radius (mean 1.6°), with the spatial extent of both phenomena falling between the boundaries of the foveola and foveal pit. Multiple regression showed MS and HB radii to be significantly associated with the macular pigment spatial profile radius. HB radius, but not MS radius, was also significantly associated with foveolar morphometry. Experiment 2 compared perceptual profiles of MS with macular pigment distribution patterns and demonstrated close agreement. The size and appearance of MS is a direct indicator of macular pigment density and distribution. Measures of HB radii are less specific, with dependence on both macular pigment density and foveal structure., Competing Interests: The authors declare no conflicts of interest.

Background: To introduce a modified surgical technique, the "parafoveal multiple curvelinear internal limiting membrane (ILM) peeling", to preserve epi-foveal ILM in myopic foveoschisis surgery. Methods: Consecutive patients with myopic foveoschisis were enrolled in the present prospective interventional case series. The surgeries were performed using transconjunctival 23-gauge system. The macular area was divided into quadrants. ILM was peeled off in a curvilinear manner centered around the site that was away from the central fovea in each quadrant. Shearing forces were used to control the direction to keep the peeling away from central fovea. ILM at central fovea of about 500 to 1000 μm was preserved by this technique. Results: This technique was performed in 20 eyes of 20 consecutive patients. Epi-foveal ILM was successfully preserved in all cases using the technique. Patients were followed up for more than 12 months. The mean postoperative logMAR visual acuity improved from 1.67 ± 0.65 preoperatively to 1.15 ± 0.49 (P = 0.015; paired t-test). Postoperative OCT examinations showed that full-thickness macular holes (MHs) did not developed in any case. Central fovea thickness decreased from 910 ± 261 μm preoperatively to 125 ± 85 postoperatively (P = 0.001; paired ttest). Conclusion: Fovea sparing ILM peeling using multiple parafoveal curvilinear peels prevents the development of postoperative full-thickness MHs in eyes with myopic foveoschisis. [ABSTRACT FROM AUTHOR]

Recent studies have shown that information from peripherally presented images is present in the human foveal retinotopic cortex, presumably because of feedback signals. We investigated this potential feedback signal by presenting noise in fovea at different object-noise stimulus onset asynchronies (SOAs), whereas subjects performed a discrimination task on peripheral objects. Results revealed a selective impairment of performance when foveal noise was presented at 250-ms SOA, but only for tasks that required comparing objects' spatial details, suggesting a task- and stimulus-dependent foveal processing mechanism. Critically, the temporal window of foveal processing was shifted when mental rotation was required for the peripheral objects, indicating that the foveal retinotopic processing is not automatically engaged at a fixed time following peripheral stimulation; rather, it occurs at a stage when detailed information is required. Moreover, fMRI measurements using multivoxel pattern analysis showed that both image and object category-relevant information of peripheral objects was represented in the foveal cortex. Taken together, our results support the hypothesis of a temporally flexible feedback signal to the foveal retinotopic cortex when discriminating objects in the visual periphery. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the characteristics of the late foveal response component (lfrc) that presents on the first slice of the second-order kernel (K2.1) in multifocal electroretinograms (mfERGs). Methods: mfERGs with 37 hexagonal stimulus elements were obtained from 27 healthy subjects under a stimulus intensity of 2.67 cds/m, base rate of 75 Hz, and a net recording time of 1 min 49.2 s, using bipolar contact lens electrodes. The responses on the centermost hexagon (with a diameter of 4.5°-5.2°) were designated as foveal mfERGs. Results: The foveal mfERG of the first-order kernel (K1) was shaped similarly to the K1 of the surrounding mfERGs. The foveal mfERG of K2.1 differed from the K2.1s of the surrounding mfERGs. This difference varied among subjects; however, the potential (0.34 ± 0.10 µV: mean ± SD) of the lfrc acutely changed at approximately 50 ms (range 48.56 ± 1.02-56.86 ± 1.99 ms). Whereas the amplitudes of the other major components of K1 and K2.1 significantly decreased with increasing refractive error, the amplitude of lfrc was not significantly correlated with refraction in this cohort. Conclusions: The lfrc was obtained only on the centermost hexagon within an appropriate recording time (<2 min). This finding reflects the particular structure and peculiar adaptiveness of the fovea, a specialized area of the human retina, and enables the estimation of foveal function in clinical practice. [ABSTRACT FROM AUTHOR]

Biederman et al. [1, 2] have shown that the priming effect does not depend on the difference between the angular sizes of the test stimulus and the primer. However, these two and other similar studies investigated only a small range of the angular sizes of stimuli. Vakhrameeva et al. [3] have shown that there exist two perceptionally different size ranges: perception of the objects with an angular size varying between 1-1.5 and 50 degrees was found to be invariant, but for the objects whose angular size is less than 1-1.5 degrees, their perception is no longer invariant. In this study, the presence of the priming effect has been investigated in the match-to-sample task with such a difference in the angular sizes of the primer and test stimuli that the sizes of the primer (about 4 degrees) and the test stimulus (about 0.5 degrees) belonged to two different size ranges. The sample stimulus was presented with and without noise superposition. It has been shown that the priming effect is suppressed when the size difference between the primer and the test stimulus is large. A congruent primer can have a positive impact on the recognition of the test objects, but this occurs under the viewing conditions complicated by noise superposition. [ABSTRACT FROM AUTHOR]

Purpose: To determine the possible relationship between foveal and subfoveal-layer thickness, visual acuity changes, foveal serous detachment heights and resolution times in spontaneously resolved central serous chorioretinopathy (CSCR) patients. Materials and Methods: Clinical data of unilateral spontaneously resolved CSCR patients were reviewed retrospectively in our clinic. Unaffected fellow eyes of patients accepted as control group. Optical Cohorens Tomography (OCT) and fundus flurescein angiography (FFA) were used to diagnose CSCR. Data of resolution time, visual acuity changes, central foveal thickness (CFT), sub-macular layer thicknesses and foveal serous detachment height were recorded. Results: Thirty eyes of 30 CSCR patients included the study. As control group unaffected eyes were used. CFT, outer nuclear layer(ONL) and photoreceptor layer thickness was thinner in affected eyes (CFT; 249.69±19.67 µm and 259.37±19.54 µm, p<0.001, ONL; 89.77±5.89 µm and 92.63±5.54 µm, p<0.001 photoreceptor layer; 70.9±3.75 µm and 76.03±4.76 µm, p<0.001). Foveal serous detachment height was 345.12±161.18 µm in patients with micropsia and 151.92 ±62.6 µm in without. (p<0.01) There was no statistically significant difference between these groups in CFT measurements. Photoreceptor and ONL thicknesses were significantly thinner in patients with final visual acuity of logMAR 0,1 than patients with visual acuity of logMAR 0. (68.29±3.25 µm, 71.7±3.5 µm p=0.032 for photoreceptor layer and 85.14±5.04 µm, 91.14±5.47 µm p=0.021 for ONL) Significant negative correlation between final CFT and logMAR visual acuity also supports these findings. Conclusion: Central foveal thickness, ONL and photoreceptor layer thickness may be a predictor for final visual acuity in spontaneously resolved CSCR patients. [ABSTRACT FROM AUTHOR]

Differences in visual capabilities are known to reflect differences in foraging behaviour even among closely related species. Among birds, the foraging of diurnal raptors is assumed to be guided mainly by vision but their foraging tactics include both scavenging upon immobile prey and the aerial pursuit of highly mobile prey. We studied how visual capabilities differ between two diurnal raptor species of similar size: Harris's hawks, Parabuteo unicinctus, which take mobile prey, and black kites, Milvus migrans, which are primarily carrion eaters. We measured visual acuity, foveal characteristics and visual fields in both species. Visual acuity was determined using a behavioural training technique; foveal characteristics were determined using ultra-high resolution spectraldomain optical coherence tomography (OCT); and visual field parameters were determined using an ophthalmoscopic reflex technique. We found that these two raptors differ in their visual capacities. Harris's hawks have a visual acuity slightly higher than that of black kites. Among the five Harris's hawks tested, individuals with higher estimated visual acuity made more horizontal head movements before making a decision. This may reflect an increase in the use of monocular vision. Harris's hawks have two foveas (one central and one temporal), while black kites have only one central fovea and a temporal area. Black kites have a wider visual field than Harris's hawks. This may facilitate the detection of conspecifics when they are scavenging. These differences in the visual capabilities of these two raptors may reflect differences in the perceptual demands of their foraging behaviours. [ABSTRACT FROM AUTHOR]

The objective of this research was to compare the features of the shape of the foveolar area with the characteristics of eye movements in reading. To measure the size of the fovea, we used the method of optical coherence tomography of the retina. Based on this method, the diameter of the upper part of fovea (fovea diameter) and fovea bottom (foveola diameter) were determined. We found a negative correlation between the fovea diameter and fixation duration and positive correlations at the level of tendency between the foveola diameter and the number of saccades performed and between the foveola diameter and the number of characters captured by eye per fixation. [ABSTRACT FROM AUTHOR]

Visual space is retinotopically mapped such that peripheral objects are processed in a cortical region outside the region that represents central vision. Despite this wellknown fact, neuroimaging studies have found information about peripheral objects in the foveal confluence, the cortical region representing the fovea. Further, this information is behaviorally relevant: disrupting the foveal confluence using transcranial magnetic stimulation impairs discrimination of peripheral objects at time-points consistent with a disruption of feedback. If the foveal confluence receives feedback of information about peripheral objects to boost vision, there should be behavioral consequences of this phenomenon. Here, we tested the effect of foveal distractors at different stimulus onset asynchronies (SOAs) on discrimination of peripheral targets. Participants performed a discrimination task on target objects presented in the periphery while fixating centrally. A visual distractor presented at the fovea ~100 ms after presentation of the targets disrupted performance more than a central distractor presented at other SOAs. This was specific to a central distractor; a peripheral distractor at the same time point did not have the same effect. These results are consistent with the claim that foveal retinotopic cortex is recruited for extra-foveal perception. This study describes a new paradigm for investigating the nature of the foveal feedback phenomenon and demonstrates the importance of this feedback in peripheral vision. [ABSTRACT FROM AUTHOR]

Images that move rapidly across the retina of the human eye blur because the retina has sluggish temporal dynamics. Voluntary smooth pursuit eye movements are modeled as matching object velocity to minimize retinal motion and prevent retinal blurring. However, "catch-up" saccades that are ubiquitous during pursuit interrupt it and disrupt clear vision. But catch-up saccades may not be a common feature of ocular pursuit, because their existence has been documented with a small moving spot, the classic pursuit stimulus, which is a weak motion stimulus that may poorly emulate larger pursuit objects. We found that spot pursuit does not generalize to that of larger objects. Observers pursued a spot or a larger virtual object with or without a superimposed spot target. Single-spot targets produced lower pursuit acceleration than larger objects. Critically, more saccadic intrusions occurred when stimuli had a central dot, even when position and velocity errors were equated, suggesting that catch-up saccades result from pursuing a single, small object or a feature on a large one. To determine what differentiates a large object from a small one, we progressively shrank the featureless virtual object and found that catch-up saccade frequency was highest when it fit in the fovea. The results suggest that pursuit of a small target or an object feature recruits a saccade mechanism that does not compensate for a weak motion signal; rather, the target compels foveation. Furthermore, catch-up saccades are likely generated by neural circuitry typically used to foveate small objects or features. [ABSTRACT FROM AUTHOR]

Disease-causing variants of a large number of genes trigger inherited retinal degeneration leading to photoreceptor loss. Because cones are essential for daylight and central vision such as reading, mobility, and face recognition, this review focuses on a variety of animal models for cone diseases. The pertinence of using these models to reveal genotype/phenotype correlations and to evaluate new therapeutic strategies is discussed. Interestingly, several large animal models recapitulate human diseases and can serve as a strong base from which to study the biology of disease and to assess the scale-up of new therapies. Examples of innovative approaches will be presented such as lentiviral-based transgenesis in pigs and adeno-associated virus ( AAV)-gene transfer into the monkey eye to investigate the neural circuitry plasticity of the visual system. The models reported herein permit the exploration of common mechanisms that exist between different species and the identification and highlighting of pathways that may be specific to primates, including humans. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Following a period of quiescence at the end of last century, the study of microsaccades has now regained strong impetus and broad attention within the vision research community. This wave of interest, partly fueled by the advent of user-friendly high-resolution eyetrackers, has attracted researchers and led to novel ideas. Old hypothesis have been revisited and new ones formulated. This article is designed to serve as a practical guide for researchers in the field. Because of the history of the field and the difficulty of measuring very small eye movements, the study of microsaccades presents peculiar challenges. Here, we summarize some of the main challenges and describe methods for assessing and improving the quality of the recordings. Furthermore, we examine how these experimental challenges have influenced analysis of the visual functions of microsaccades and critically review current evidence on three long-debated proposals: the maintenance of fixation, the prevention of visual fading, and the exploration of fine spatial detail. [ABSTRACT FROM AUTHOR]

A set of structured demonstrations of the vividness of peripheral color vision is provided by arrays of multicolored disks scaled with eccentricity. These demonstrations are designed to correct the widespread misconception that peripheral color vision is weak or nonexistent. [ABSTRACT FROM AUTHOR]

Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ∼45,000 cells·mm-2, and a temporal area with lower densities (38,000-39,000 cells·mm-2). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cycles·degree-1. Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]