Fast and nonuniform dynamics of perisaccadic vision in the central fovea

Humans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primates’ social grooming, which—like most explorations of fine patterns—primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the perisaccadic time course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.

The RAP study, report 4: morphological and topographical characteristics of multifocal macular neovascularization type 3

Purpose To report on the morphological characteristics and regional distribution of multifocal macular neovascularization type 3 (mMNV3). Methods Twenty-two consecutive eyes of 21 patients with mMNV3 were included using multimodal imaging. The count and stage of lesions of all MNV types and the existence of exudate and hemorrhage were determined. Also, we addressed the regional distribution of MNV3 lesions between the superior-inferior and the nasal-temporal halves of the macula, and the range of the distance of the lesions from the central fovea. Furthermore, we explored the number of feeding vessels including the cilioretinal artery. Results We found 51 lesions in 22 eyes of 21 patients. They were bifocal in 16 (73%) eyes, trifocal in 5 (23%), and quadrifocal in one (4%). No lesion of MNV1 or 2 was found. Fifteen (68%), 2 (9%), and 16 (73%) eyes were associated with retinal hard exudate, subretinal pigment epithelium exudate, and intraretinal hemorrhage, respectively. Thirty (59%) lesions were located in the temporal half of the macula, whereas 21 (41%) were located nasally (p = 0.07). One (2%) lesion was closer than 500 µm, 49 (96%) between 500 and 1500 µm, and one (2%) between 1500 and 3000 µm. The lesions were supplied by one arteriole in one (4%) eye, two arterioles in 16 (73%) eyes, and 3 arterioles in 5 (23%) eyes. The CRA contributed as a feeding vessel in 5 (23%) eyes. Conclusion The multifocal variant of MNV3 has specific morphological and topographical characteristics. Multimodal imaging allows the understanding of the pathomorphological condition in more detail.

Factors Differentiating the Antioxidant Activity of Macular Xanthophylls in the Human Eye Retina

Macular xanthophylls, which are absorbed from the human diet, accumulate in high concentrations in the human retina, where they efficiently protect against oxidative stress that may lead to retinal damage. In addition, macular xanthophylls are uniquely spatially distributed in the retina. The zeaxanthin concentration (including the lutein metabolite meso-zeaxanthin) is ~9-fold greater than lutein concentration in the central fovea. These numbers do not correlate at all with the dietary intake of xanthophylls, for which there is a dietary zeaxanthin-to-lutein molar ratio of 1:12 to 1:5. The unique spatial distributions of macular xanthophylls—lutein, zeaxanthin, and meso-zeaxanthin—in the retina, which developed during evolution, maximize the protection of the retina provided by these xanthophylls. We will correlate the differences in the spatial distributions of macular xanthophylls with their different antioxidant activities in the retina. Can the major protective function of macular xanthophylls in the retina, namely antioxidant actions, explain their evolutionarily determined, unique spatial distributions? In this review, we will address this question.

Increase of central foveal and temporal choroidal thickness in patients with inactive thyroid eye disease

Background In this study, we aimed to compare the choroidal thickness between a group of Korean patients with inactive thyroid eye disease (TED) and a control group of Korean patients and to analyze the variables affecting choroidal thickness. Methods Patients diagnosed with inactive TED and without TED who underwent optical coherence tomography and axial length measurements were included and classified into the TED group and control group. Choroidal thickness was measured using images acquired in enhanced depth imaging (EDI) mode by cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, UAS) at the central fovea and points 1.5 mm nasal and 1.5 mm temporal from the central fovea using a caliper tool provided by OCT software. Results The mean central foveal choroidal thickness was 294.2 ± 71.4 µm and 261.1 ± 47.4 µm in the TED and control groups, respectively, while the mean temporal choroidal thickness was 267.6 ± 67.5 µm and 235.7 ± 41.3 µm in the TED and control groups, respectively, showing significant differences between the two groups (P = 0.011, P = 0.008). The mean nasal choroidal thickness was 232.1 ± 71.7 µm and 221.1 ± 59.9 µm in the TED and control groups, respectively, showing no significant difference between the two groups (P = 0.421). Multivariate regression analysis showed the factors affecting central foveal choroidal thickness were age, axial length, and degree of exophthalmos, and factors affecting temporal choroidal thickness were age and degree of exophthalmos. Conclusions Central foveal and temporal choroidal thickness were significantly thicker in patients with inactive TED than in control subjects, while age, axial length, and degree of exophthalmos were identified as major factors affecting choroidal thickness.

Comparative Study of the Intravenous Infusion of Umbilical Cord Mesenchymal Stem Cells and A Modified Sub-Tenon’s Capsule Injection of Triamcinolone Acetonide in Retinitis Pigmentosa Combined with Macular Edema

Background: Retinitis pigmentosa (RP) is a hereditary retinal degenerative disease leading to eventual blindness. Macular edema (ME) is a frequent complication in RP. When RP is combined with ME, the visual impairment further worsens. Well controlled ME is crucial to prevent RP from advancing. We compared the intravenous infusion of umbilical cord mesenchymal stem cells (UCMSCs) and a modified sub-Tenon’s capsule injection of triamcinolone acetonide (TA) in the treatment of RP combined with ME to assess their safety and efficacy in eliminating macular edema. Methods: A phase I/II clinical trial enrolled 20 patients was conducted. Patients in the UCMSCs infusion group received a single intravenous infusion of 3 × 106 UCMSCs, and patients in the TA injection group received a modified sub-Tenon’s capsule injection of 20 mg of TA. All patients were followed up for 6 months. Systemic and ophthalmological investigations were performed to assess the safety and efficacy.Results: There were no severe adverse effects in both groups. At 2nd month follow up, the thickness of the central fovea in TA injection group was significantly lower than that in UCMSCs infusion group (P<0.05). The gradient of decrease of average macular thickness in TA injection group was significantly higher than that in UCMSCs group (P<0.05). At 6th month follow up, the central fovea thickness was higher in the TA injection group than that in UCMSCs infusion group (P<0.05). The average amplitude/latency (A/L) of the P2 wave in the flash visual evoked potential (FVEP) in UCMSCs infusion group was significantly higher at 6th month follow up than that in TA injection group (P<0.05). Conclusions: This study suggests TA injection is more effective at reducing ME in a short term. UCMSC intravenous infusion exerts slow but persistent action in reducing ME, and can maintain the visual function for a longer time. These approaches can be applied separately or jointly depending on the disease condition for patients to benefit maximumly. Trial registration: chictr.org.cn: ChiCTR-ONC-16008839. Registered on July 14, 2016.

Visual Adaptations in Predatory and Scavenging Diurnal Raptors

Ecological diversity among diurnal birds of prey, or raptors, is highlighted regarding their sensory abilities. While raptors are believed to forage primarily using sight, the sensory demands of scavengers and predators differ, as reflected in their visual systems. Here, I have reviewed the visual specialisations of predatory and scavenging diurnal raptors, focusing on (1) the anatomy of the eye and (2) the use of vision in foraging. Predators have larger eyes than scavengers relative to their body mass, potentially highlighting the higher importance of vision in these species. Scavengers possess one centrally positioned fovea that allows for the detection of carrion at a distance. In addition to the central fovea, predators have a second, temporally positioned fovea that views the frontal visual field, possibly for prey capture. Spatial resolution does not differ between predators and scavengers. In contrast, the organisation of the visual fields reflects important divergences, with enhanced binocularity in predators opposed to an enlarged field of view in scavengers. Predators also have a larger blind spot above the head. The diversity of visual system specializations according to the foraging ecology displayed by these birds suggests a complex interplay between visual anatomy and ecology, often unrelatedly of phylogeny.

Septo-optic dysplasia with fovea plana: A case report

Septo-optic dysplasia (SOD) is characterized by optic nerve hypoplasia, pituitary gland hypoplasia, and midline abnormalities of the brain. The phenotype of SOD is highly heterogeneous, and the existence of at least two features is considered sufficient for diagnosis. Fovea plana is the absence of a foveal pit in the central fovea, and despite being a developmental abnormality of the fovea, good visual acuity may be retained in some individuals. In this case, a 12-year-old female presented to the ophthalmology clinic with the complaint of blurred vision in her right eye. In dilated fundus examination, optic disc hypoplasia and no foveal light reflex were seen. Magnetic resonance imaging and optical coherence tomography revealed optic nerve, brain midline, and foveal abnormalities. The patient was diagnosed as having SOD with optic nerve hypoplasia and septum pellucidum agenesis, and fovea plana. Both SOD and fovea plana are rare conditions, and there are several reports in the literature that separately describe their clinical features. The most important aspect of this case report is to reveal the unusual co-existence of SOD and fovea plana in a young patient.

Why Is Zeaxanthin the Most Concentrated Xanthophyll in the Central Fovea?

Diet-based xanthophylls (zeaxanthin and lutein) are conditionally essential polar carotenoids preferentially accreted in high concentrations (1 mM) to the central retina, where they have the capacity to impart unique physiologically significant biophysical biochemical properties implicated in cell function, rescue, and survival. Macular xanthophylls interact with membrane-bound proteins and lipids to absorb/attenuate light energy, modulate oxidative stress and redox balance, and influence signal transduction cascades implicated in the pathophysiology of age-related macular degeneration. There is exclusive transport, sequestration, and appreciable bioamplification of macular xanthophylls from the circulating carotenoid pool to the retina and within the retina to regions required for high-resolution sensory processing. The distribution of diet-based macular xanthophylls and the lutein metabolite meso-zeaxanthin varies considerably by retinal eccentricity. Zeaxanthin concentrations are 2.5-fold higher than lutein in the cone-dense central fovea. This is an ~20-fold increase in the molar ratio relative to eccentric retinal regions with biochemically detectable macular xanthophylls. In this review, we discuss how the differences in the specific properties of lutein and zeaxanthin could help explain the preferential accumulation of zeaxanthin in the most vulnerable region of the macula.

The Difference in Repeatability of Automated Superficial Retinal Vessel Density according to the Measurement Area Using OCT Angiography

Purpose. To evaluate the difference in the repeatability of automated superficial retinal vessel density and foveal avascular zone (FAZ) metrics according to the measurement area of optical coherence tomography angiography (OCTA). Methods. A total of 127 normal eyes from 127 healthy subjects were included. Macular angiography images were acquired from all subjects using the Zeiss Cirrus 5000 with AngioPlex™ OCTA software. Scans of 3 × 3 mm and 6 × 6 mm were each performed twice in a randomly arranged sequence. Vessel density (VD), perfusion density (PD), and FAZ metrics of the superficial capillary plexus were calculated automatically for all scans, and the repeatabilities for both scan patterns were assessed based on intraclass correlation (ICC), coefficient of variation (CV), and coefficient of repeatability (CR) parameters. The average measured values in the two scan patterns were also compared. Results. VD was significantly greater in the 3 × 3 mm scan than in the 6 × 6 mm scan according to all parameters, whereas PD was significantly less in the 3 × 3 mm scan than in the 6 × 6 mm scan. The ICCs for VDs in the central fovea were 0.826 and 0.741 for the 3 × 3 and 6 × 6 mm scans, respectively, and the CVs were 8.00% and 12.75%. For PDs, the ICCs were 0.839 and 0.762 and the CVs were 9.32% and 14.90%. The FAZ metrics in the 3 × 3 mm scan showed good repeatability with an ICC >0.75 and a CV <10.0%. However, all ICCs for the 6 × 6 mm scans were <0.75, and the CVs were all >10%. Conclusions. The 6 × 6 mm macular angiography scans resulted in lower repeatabilities than the 3 × 3 mm scans according to all OCTA parameters, particularly in the central fovea and FAZ metrics. The 3 × 3 mm scan was more suitable than the 6 × 6 mm scan for analyzing macular microvascular density and FAZ metrics.