Vertical Meridian Research Articles

How the window of visibility varies around polar angle.

Contrast sensitivity, the amount of contrast required to discriminate an object, depends on spatial frequency (SF). The contrast sensitivity function (CSF) peaks at intermediate SFs and drops at other SFs. The CSF varies from foveal to peripheral vision, but only a couple of studies have assessed how the CSF changes with polar angle of the visual field. For many visual dimensions, sensitivity is better along the horizontal than the vertical meridian and at the lower than the upper vertical meridian, yielding polar angle asymmetries. Here, for the first time, to our knowledge, we investigate CSF attributes around polar angle at both group and individual levels and examine the relations in CSFs across locations and individual observers. To do so, we used hierarchical Bayesian modeling, which enables precise estimation of CSF parameters. At the group level, maximum contrast sensitivity and the SF at which the sensitivity peaks are higher at the horizontal than vertical meridian and at the lower than the upper vertical meridian. By analyzing the covariance across observers (n = 28), we found that, at the individual level, CSF attributes (e.g., maximum sensitivity) across locations are highly correlated. This correlation indicates that, although the CSFs differ across locations, the CSF at one location is predictive of that at another location. Within each location, the CSF attributes covary, indicating that CSFs across individuals vary in a consistent manner (e.g., as maximum sensitivity increases, so does the corresponding SF), but more so at the horizontal than the vertical meridian locations. These results show similarities and uncover some critical polar angle differences across locations and individuals, suggesting that the CSF should not be generalized across isoeccentric locations around the visual field.

Зміни у показниках периферійного зору баскетболісток 11–12 років під впливом спеціально підібраних вправ

In team game sports, peripheral vision can be useful for simultaneously tracking the movements of opponents and teammates. The purpose of the study: to experimentally test the effectiveness of specially selected exercises aimed at changes in the peripheral vision of basketball players aged 11-12 years. Research methods: theoretical analysis of scientific and methodological literature, pyrometry method, pedagogical experiment, methods of mathematical statistics. The device ‘Forster's Perimeter’ was used to determine the index of peripheral visual field. The field of vision was determined for the left and right eyes separately for the white and green colours of the two main meridians - horizontal outward (to the temple) and to the middle (to the nose) and vertical - upward and downward. The study was conducted at the research laboratory of the Kharkiv State Academy of Physical Culture. The study involved 30 female basketball players from Kharkiv aged 11-12 years. In order to establish the effectiveness of using specially selected exercises during training, young basketball players were divided into control and experimental groups, each of which consisted of 15 girls. For 4 months, the training process of the experimental group was based on the standard training programme for basketball for children and youth sports schools and was supplemented by specially selected sets of exercises aimed at developing peripheral vision and improving the condition of the eye muscles. Special sets of exercises aimed at developing peripheral vision. Results of the study. The ‘Forster Perimeter’ device does not allow to set the field of vision in the selected direction by more than 90º. It should be noted that the index of peripheral vision horizontally outward, both with the right and left eyes, for both colours in all basketball players exceeded this index. Thus, it was not possible to establish the indicators of peripheral vision in the horizontal outward direction and to study the influence of specially selected exercises on these indicators. The analysis of indicators in the direction up, down and inwards revealed the highest indicators along the vertical meridian with the right and left eyes downwards, both in the CG and EG. Comparing the indicators of peripheral vision of the right and left eyes to white, it was found that in the EG there were significant differences in the indicators upwards (t=2.54, p<0.05) and in the middle (t=4.47, p<0.05), in the CG - in all three directions (t=2.43, p<0.05; t=2.27, p<0.05, t=3.56, p<0.05. In indicators of peripheral vision of the right and left eyes for green colour significant differences are observed only in EG in the upward direction (t=2.19; p<0.05) After the pedagogical experiment the repeated testing was conducted, the results of which indicated a significant improvement of indicators of peripheral vision of basketball players of EC of the right eye both for white and green colour in all three directions (p<0.005). Significant changes in the indicators of peripheral vision of the left eye occurred only for white colour along the vertical meridian downwards (t=2.06; p<0.05) and upwards (t=2.04; p<0.05). For other indicators, the changes were positive, but not significant. Conclusions. The use of specially selected exercises positively influenced on indicators of peripheral vision of sportswomen of 11-12 years old of EG. Thus, the improvement in the right eye was 5.08% upwards, 6.08% downwards, 9.58% in the middle of white colour; in green colour - 11.82%, 5.86%, 5.91%, respectively. In the left eye, the improvement was 6.58% for white, 7.57% for blue, and 1.08% for green; 7.38%, 7.81%, 5.70% for green, respectively.

Relationship between Choroidal Thickness and Anterior Scleral Thickness in Patients with Keratoconus.

To evaluate the relationship between choroidal thickness (CT) and anterior scleral thickness (AST) in patients with subclinical keratoconus (SKC) and established keratoconus (KC). This single-center prospective case-control study included 97 eyes of 97 patients: 44 KC eyes, 14 SKC eyes, and 39 age- and axial length (AL)-matched healthy eyes. Using swept-source optical coherence tomography, the AST was manually measured in four directions and the CT was obtained automatically from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Principal component analysis (PCA) was used to linearly reduce the dimensionality of nine CT inputs to one significant component, CT1. A multivariate model was created to evaluate the association between CT1, AST, and several ocular parameters in SKC and KC patients. Partial correlation was then performed to adjust the confounding factors and to examine the effect of AST on CT1. The PCA showed that CT1 accounts for 86.54% of the total variance in the nine original CTs of the ETDRS grid. The CT1 model was associated with age, AL, and AST in the superior meridian in SKC eyes, whereas in KC eyes, it was correlated with gender, age, AL, and AST in the inferior meridian (p < 0.001). The partial correlation between CT1 and AST in the superior zone was found to be significant, positive, and strong in SKC eyes (r = 0.79, p = 0.019), whereas a significant, positive, and moderate correlation between CT1 and AST at the inferior zone (r = 0.41, p = 0.017) was observed in KC eyes. Choroidal tissue was significantly correlated with the anterior sclera across the vertical meridian. This relationship was observed over the superior sclera in SKC eyes, whereas in established KC, it was over the inferior sclera. These results reveal new insights regarding the interactions between the anterior and posterior structures of the KC eyes and confirm the enigma of the pathophysiology of KC.

Morphology of the normative human cone photoreceptor mosaic and a publicly available adaptive optics montage repository.

Adaptive optics ophthalmoscopy has enabled visualization of the in vivo human photoreceptor mosaic in health, disease and its treatment. Despite this, the clinical utility of the imaging technology has been limited by a lack of automated analysis techniques capable of accurately quantifying photoreceptor structure and a lack of an available normative image database. Here, we present a fully automated algorithm for estimating cone spacing and density over a complete adaptive optics montage along with a database of normative images and cone densities. We imaged the cone mosaics surrounding the fovea and along the horizontal and vertical meridians of fifty normal-sighted controls with a custom-built, multimodal adaptive optics scanning light ophthalmoscope. Cone spacing was automatically measured in the frequency domain and spacing measurements were converted to estimates of cone density at all locations across the montage. Consistent with previous reports, cone density measurements were highest near fovea (152,906 ± 53,209 cones/mm2) and decreased exponentially with eccentricity. A 2.5-fold variation was found in cone density estimates at 0.1mm, this variation decreased to 1.75-fold at 1mm. We provide all images, mosaic quantifications, and automated software open source. This database will aid investigators in translating adaptive optics ophthalmoscopy to clinical applications.

Corneal Curvature Change After Strabismus Surgery: An Experience from a Single-academic Center

Objective: This study aimed to explore corneal curvature changes following strabismus surgery using a quadric surface fitting model to address ocular misalignment. Material and Methods: In this prospective cross-sectional study, 54 completed cases (84 eyes) of patients aged 6–60 years old (mean 10 years old) undergoing horizontal rectus muscle surgery were examined using placido-based keratometry with the Oculus Keratograph 5M system. Data on corneal curvature were collected one week pre-operation, and again one week, one month, and three months post-operation. Asphericity in the vertical meridian (Qy) and horizontal meridian (Qx), and surgical-induced astigmatism (SIA) were calculated. Results: The 84 eyes included were categorized into three groups: horizontal muscle surgeries, oblique muscle surgery, and combined horizontal and oblique muscle surgeries. Significant corneal prolation (steep central, flat peripheral) was revealed in the vertical meridian (Qy) at 3 months postoperatively for lateral rectus (LR) recession in the first group (p &lt; 0.001), and the mean SIA was 0.45 D (95% CI: 0.35–0.56 D). A similar effect was seen in the vertical meridian of the third group (p &lt; 0.01), with a mean SIA at 3 months of 0.27 D (95% CI: 0.23–0.32 D). Conclusion: Lateral rectus muscle recession induces corneal vertical prolation for up to 3 months post-operation. Surgeons are thus advised to re-evaluate refraction and defer contact lens refitting, refractive surgery, and intraocular lens calculations for at least 3 months after the procedure.

New results in stereopsis and Listing's law.

Human eyes' optical components are misaligned. This study presents comprehensive geometric constructions in the binocular system, with the eye model incorporating the fovea that is displaced from the posterior pole and the lens that is tilted away from the eye's optical axis. It extends their previously considered horizontal misalignment with the vertical components. When the eyes' binocular posture changes, 3D spatial coordinates of the retinal disparity (iso-disparity curves), the subjective vertical horopter, and the eye's torsional orientation transformations are visualized in GeoGebra's simulations. The consequences and functional roles of vertical misalignment of the eye's optical components are explained in the following findings: (1) The classic Helmholtz theory, which states that the subjective vertical retinal meridian inclination to the retinal horizon explains the backward tilt of the perceived vertical horopter, is less relevant when the eye's optical components are misaligned. Instead, the lens vertical tilt provides the retinal vertical criterion that explains the experimentally measured vertical horopter inclination. (2) Listing's law, which originally restricts single-eye torsional positions and has imprecise binocular extensions, is formulated for binocular fixations using Euler's rotation theorem. It, however, replaces Listing's plane, which is defined for eyes looking at infinity, with the eyes muscles' natural tonus resting position corresponding to the abathic distance fixation of empirical straight frontal horopter. This new meaning of Listing's plane provides neurophysiological significance that has remained elusive.

Visual adaptation is more pronounced at the horizontal than vertical meridian

Visual adaptation is more pronounced at the horizontal than vertical meridian

Corneal changes after large (9mm) lateral rectus muscle recession measured with Pentacam®

ABSTRACT Introduction: The aim of this study was to evaluate alterations in corneal astigmatism, axial anterior corneal curvature, anterior chamber depth, and central corneal thickness (CCT) two months after the unilateral recession of lateral rectus muscle in children. Methods: This prospective study included 37 children with intermittent exotropia who would undergo unilateral lateral rectus muscle recession. All measurements were performed using Pentacam®. Comparisons were made between the operated and fellow unoperated eyes, pre- and post-operatively. The assessment was made for changes in the radius of axial curvature on major meridians at 3 and 3.5 mm from the optical corneal center in the mid-peripheral zone. Astigmatism changes of the anterior and posterior corneal surface were calculated using vector analysis software (astigMATIC®). The interaction between age or CCT and postoperative changes in anterior and posterior surface corneal astigmatism were examined with ANOVA model. Results: In the intervention group, changes in anterior and posterior corneal surface astigmatism were statistically significant, with a mean increase of 0.56Dx90 and 0.08Dx87, respectively. In the mid-peripheral corneal zone, an increase was observed in the radius of anterior corneal axial curvature, more evident temporal 3 and 3.5 mm from the corneal center on the horizontal meridian, with corresponding decrease superiorly and inferiorly at 3 and 3.5 mm from the corneal center on the vertical meridian. Discussion: The changes in total astigmatism of the operated eyes are mainly attributed to the anterior corneal surface. These changes are associated with flattening in the 180 meridian of the cornea, leading to a shift to “with-the-rule” astigmatism.

Presaccadic Attention Enhances and Reshapes the Contrast Sensitivity Function Differentially around the Visual Field.

Contrast sensitivity (CS), which constrains human vision, decreases from fovea to periphery, from the horizontal to the vertical meridian, and from the lower vertical to the upper vertical meridian. It also depends on spatial frequency (SF), and the contrast sensitivity function (CSF) depicts this relation. To compensate for these visual constraints, we constantly make saccades and foveate on relevant objects in the scene. Already before saccade onset, presaccadic attention shifts to the saccade target and enhances perception. However, it is unknown whether and how it modulates the interplay between CS and SF, and if this effect varies around polar angle meridians. CS enhancement may result from a horizontal or vertical shift of the CSF, increase in bandwidth, or any combination. In addition, presaccadic attention could enhance CS similarly around the visual field, or it could benefit perception more at locations with poorer performance (i.e., vertical meridian). Here, we investigated these possibilities by extracting key attributes of the CSF of human observers. The results reveal that presaccadic attention (1) increases CS across SF, (2) increases the most preferred and the highest discernable SF, and (3) narrows the bandwidth. Therefore, presaccadic attention helps bridge the gap between presaccadic and postsaccadic input by increasing visibility at the saccade target. Counterintuitively, this CS enhancement was more pronounced where perception is better-along the horizontal than the vertical meridian-exacerbating polar angle asymmetries. Our results call for an investigation of the differential neural modulations underlying presaccadic perceptual changes for different saccade directions.

Choroidal vascular changes in early-stage myopic maculopathy from deep learning choroidal analysis: a hospital-based SS-OCT study

BackgroundThe objective of this study is to illustrate the changes in the choroidal vasculature in individuals with diffuse chorioretinal atrophy (DCA, early-stage myopic maculopathy) and investigate the association between them.MethodsThis study included 1418 highly myopic eyes from 720 participants aged 18 − 60 years from the Wenzhou High Myopia Cohort Study. These participants underwent comprehensive ophthalmic assessments. Myopic maculopathy classification followed the Meta-PM system, with pathological myopia defined as myopic maculopathy of DCA or severer. Eyes with myopic maculopathy categorized as no macular lesions (C0), tessellated fundus (C1), and DCA (C2) were enrolled in the analysis. Choroidal images were obtained from swept-source optical coherence tomography (SS-OCT), and the images were processed with a deep learning-based automatic segmentation algorithm and the Niblack auto-local threshold algorithm.ResultsDCA was detected in 247 eyes (17.4%). In comparison to eyes with C0, those with C2 exhibited significant reductions in choroidal thickness (ChT), luminal area (LA), and stromal area (SA) across all evaluated regions (all P < 0.001). An increase in choroidal vascular index (CVI) was observed in all regions, except for the nasal perifoveal (N2) and inferior perifoveal (I2) regions (all P < 0.01). Multivariable logistic regression analysis revealed a negative association between the presence of DCA and increases in choroidal LA and SA (odds ratio ≤ 0.099, P < 0.001). Multivariable linear regression analysis showed that the mean deviation of the visual field test was positively associated with LA and SA at the vertical meridian (B = 1.512, P < 0.001 for LA; B = 1.956, P < 0.001 for SA). Furthermore, the receiver operating characteristic curve analyses showed the optimal ChT to diagnose pathological myopia was 82.4 µm in the N2 region, the LA was 0.076 mm2 and the SA was 0.049 mm2, with area under the curves of 0.916, 0.908, and 0.895, respectively.ConclusionsThe results of this study indicated that both the presence of DCA and visual function impairment were associated with reductions in choroidal perfusion and stromal components. Moreover, we established threshold values for choroidal parameters in diagnosing pathological myopia, offering valuable references for clinical diagnosis and management.

How the window of visibility varies around polar angle.

Contrast sensitivity, the amount of contrast required to detect or discriminate an object, depends on spatial frequency (SF): The Contrast Sensitivity Function (CSF) peaks at intermediate SFs and drops at lower and higher SFs and is the basis of computational models of visual object recognition. The CSF varies from foveal to peripheral vision, but only a couple studies have assessed changes around polar angle of the visual field. Sensitivity is generally better along the horizontal than the vertical meridian, and better at the lower vertical than the upper vertical meridian, yielding polar angle asymmetries. Here, we investigate CSF attributes at polar angle locations at both group and individual levels, using Hierarchical Bayesian Modeling. This method enables precise estimation of CSF parameters by decomposing the variability of the dataset into multiple levels and analyzing covariance across observers. At the group level, peak contrast sensitivity and corresponding spatial frequency with the highest sensitivity are higher at the horizontal than vertical meridian, and at the lower than upper vertical meridian. At an individual level, CSF attributes (e.g., maximum sensitivity, the most preferred SF) across locations are highly correlated, indicating that although the CSFs differ across locations, the CSF at one location is predictive of the CSF at another location. Within each location, the CSF attributes co-vary, indicating that CSFs across individuals vary in a consistent manner (e.g., as maximum sensitivity increases, so does the SF at which sensitivity peaks), but more so at the horizontal than the vertical meridian locations. These results show similarities and uncover some critical polar angle differences across locations and individuals, suggesting that the CSF should not be generalized across iso-eccentric locations around the visual field. Our window of visibility varies with polar angle: It is enhanced and more consistent at the horizontal meridian.

Posterior Eye Shape in Myopia

PurposeTo explore prevalence and associated factors of abnormalities of the posterior eye shape in dependence of axial length. DesignPopulation-based study. ParticipantsOut of the participants (n=3468) of the Beijing Eye Study, we included all eyes with an axial length of ≥25 mm, and a randomized sample of eyes with an axial length of <25 mm. MethodsUsing 30°-wide, serial horizontal, and fovea-centered radial, optical coherence tomographic (OCT) images, we examined location and depth of the most posterior point of the retinal pigment epithelium/Bruch´s membrane line (PP-RPE/BML). Main Outcome ParametersPrevalence and depth of an extrafoveal PP-RPE/BML. ResultsThe study included 366 eyes (314 individuals;age:63.7±9.7 years). On the radial OCT scans, the PP-RPE/BML was located in the foveola in 190 (51.9%;95%CI:46.9,56.9) eyes, in 121 (33.1%;95%CI:28.1,38.1) eyes in the 6 o´clock part of the vertical meridian at a mean distance of 1.73±0.70mm from the foveola, and in 54 (14.8%;95%CI:11.1,18.4) eyes in the 12 o´clock part of the vertical meridian at a distance of 2.01±0.66mm from the foveola. Deeper PP-RPE/BML depth increased with longer axial length (beta:0.28;B:12.3;95%CI:7.5,17.1;P<0.001), female sex (beta:0.17;B:30.2;95%CI:10.7,49.6;P=0.002), and higher corneal astigmatism (beta:0.12;B:13.9;95%CI:1.50,26.3;P=0.03). On the horizontal OCT scans, the PP-RPE/BML was located in the foveola in 304 (83.1%;95%CI:79.2,86.9) eyes, between the foveola and the optic disc in 36 (9.8%;95%CI:6.8,12.9) eyes (mean depth: 119±142μm; mean distance:1.59±0.76mm from the foveola), and temporal to the foveola in 26 (7.1%;95%CI:4.5,9.8) eyes (depth:71±46μm; distance:1.20±0.60mm). Higher prevalence of an extrafoveal PP-RPE/BML correlated with longer axial length (OR:1.55;95%CI:1.28,1.89;P<0.001), higher corneal astigmatism (OR:1.78;95%CI:1.14,2.79;P=0.01) and female sex (OR:2.74;95%CI:1.30,5.77;P=0.008). The curvature of the RPE/BM line at the posterior pole was similar to the RPE/BM line curvature outside of the posterior pole in 309 (84.4%;95%CI:80.7,88.2) eyes, and it was steeper (i.e., smaller curvature radius) in 57 (15.6%;95%CI:12.1,19.1) eyes. In these eyes, axial length was longer (24.41±1.78mm versus 27.74±1.88mm;P<0.001). ConclusionsWith longer axial length, the foveola is more often located outside of the geometrical posterior pole. It may be of importance for biometric axial length measurements. An extrafoveal location of the PP-RPE/BML may be due to an axial elongation-associated, meridionally asymmetric enlargement of Bruch´s membrane in the fundus midperiphery.

Changes in the Thickness of the Sublens Water Layer in Patients Using Scleral Lenses

Purpose of the study. To analyze the change in the thickness of the sub­lens water layer depending on the time of wearing lenses in patients using scleral lenses using the SkyOptix Laboratory lenses as an example.Patients and methods. To determine the thickness of the sublens water layer in the vertical and horizontal meridians, a study was performed in 33 people in 46 eyes. Among the patients there were 25 men and 8 women, from 18 to 59 years old (mean 37.3 ± 9.5 years). The main indication for the use of scleral lenses was the ineffectiveness of other methods of vision correction.Results. The mean sublens water layer thickness reduction in the total group of examined patients using scleral lenses was 9.3 % or 37.73 μm after 1 hour of wear and 20.8 % or 84.48 μm after 4 hours of wear compared to initial values.Conclusions. The largest and clinically significant changes in the thickness of the sublens water layer occur during the first hour of lens wear, which, according to our study, is approximately 40 microns. Considering the temporal dynamics of changes in the thickness of the sublens water layer, the final calculation of the parameters must be made no earlier than after 1 hour of wearing the scleral lens. The thickness of the sublens water layer should be assessed in relation to the time spent in the scleral lens. According to our survey, over the entire period of observation in all patients using scleral lenses, there is a decrease in the thickness of the sublens water layer over time of wearing, which requires further additional research to determine identifying the exact causes and factors underlying this process.

Pre-saccadic Preview Shapes Post-Saccadic Processing More Where Perception is Poor.

The pre-saccadic preview of a peripheral target enhances the efficiency of its post-saccadic processing, termed the extrafoveal preview effect. Peripheral visual performance -and thus the quality of the preview- varies around the visual field, even at iso-eccentric locations: it is better along the horizontal than vertical meridian and along the lower than upper vertical meridian. To investigate whether these polar angle asymmetries influence the preview effect, we asked human participants (to preview four tilted gratings at the cardinals, until a central cue indicated to which one to saccade. During the saccade, the target orientation either remained or slightly changed (valid/invalid preview). After saccade landing, participants discriminated the orientation of the (briefly presented) second grating. Stimulus contrast was titrated with adaptive staircases to assess visual performance. Expectedly, valid previews increased participants' post-saccadic contrast sensitivity. This preview benefit, however, was inversely related to polar angle perceptual asymmetries; largest at the upper, and smallest at the horizontal meridian. This finding reveals that the visual system compensates for peripheral asymmetries when integrating information across saccades, by selectively assigning higher weights to the less-well perceived preview information. Our study supports the recent line of evidence showing that perceptual dynamics around saccades vary with eye movement direction.

Do microsaccades vary with discriminability around the visual field?

Microsaccades-tiny fixational eye movements-improve discriminability in high-acuity tasks in the foveola. To investigate whether they help compensate for low discriminability at the perifovea, we examined microsaccade characteristics relative to the adult visual performance field, which is characterized by two perceptual asymmetries: horizontal-vertical anisotropy (better discrimination along the horizontal than vertical meridian) and vertical meridian asymmetry (better discrimination along the lower than upper vertical meridian). We investigated whether and to what extent microsaccade directionality varies when stimuli are at isoeccentric locations along the cardinals under conditions of heterogeneous discriminability (Experiment 1) and homogeneous discriminability, equated by adjusting stimulus contrast (Experiment 2). Participants performed a two-alternative forced-choice orientation discrimination task. In both experiments, performance was better on trials without microsaccades between ready signal onset and stimulus offset than on trials with microsaccades. Across the trial sequence, the microsaccade rate and directional pattern were similar across locations. Our results indicate that microsaccades were similar regardless of stimulus discriminability and target location, except during the response period-once the stimuli were no longer present and target location no longer uncertain-when microsaccades were biased toward the target location. Thus, this study reveals that microsaccades do not flexibly adapt as a function of varying discriminability in a basic visual task around the visual field.

BOLD Contrast Response Characteristics of Aberrant Voxels with Bilateral Visual Population Receptive Fields in Human Albinism.

Albinism is an inherited disorder characterized by disrupted melanin production in the eye, and often in the skin and hair. This retinal hypopigmentation is accompanied by pathological decussation of many temporal retinal afferents at the optic chiasm during development, ultimately resulting in partially superimposed representations of opposite visual hemifields in each cortical hemisphere. Within these aberrant regions of hemifield overlap, individual voxels have been shown to have bilateral, dual population receptive fields (pRFs) responding to roughly mirror-image locations across the vertical meridian. Nonetheless, how these two conflicting inputs combine to determine a voxel's response to image contrast is still unknown. To address this, we stimulated the right and left hemifields with separately controlled sinusoidal gratings, each having a variety of contrasts (0, 8, 20, 45, 100%), and extracted voxel-wise BOLD response amplitudes to each contrast combination in visual areas V1-V3. We then compared voxels' responses to each hemifield stimulated individually with conditions when both hemifields were stimulated simultaneously. We hypothesized that simultaneous stimulation of the two pRF components will result in either a suppressive or facilitative interaction. However, we found that BOLD responses to simultaneous stimulation appeared to reflect simple summation of the neural activity from the individual hemifield conditions. This suggests that the superimposed opposite hemifield representations do not interact. Thus, dual pRFs in albinism likely reflect two co-localized, but functionally independent populations of neurons each of which respond to a single hemifield. This finding is commensurate with psychophysical studies which have shown no clear perceptual interaction between opposite visual hemifields in human albinism.

The resolution of face perception varies systematically across the visual field.

Visual abilities tend to vary predictably across the visual field-for simple low-level stimuli, visibility is better along the horizontal vs. vertical meridian and in the lower vs. upper visual field. In contrast, face perception abilities have been reported to show either distinct or entirely idiosyncratic patterns of variation in peripheral vision, suggesting a dissociation between the spatial properties of low- and higher-level vision. To assess this link more clearly, we extended methods used in low-level vision to develop an acuity test for face perception, measuring the smallest size at which facial gender can be reliably judged in peripheral vision. In 3 experiments, we show the characteristic inversion effect, with better acuity for upright faces than inverted, demonstrating the engagement of high-level face-selective processes in peripheral vision. We also observe a clear advantage for gender acuity on the horizontal vs. vertical meridian and a smaller-but-consistent lower- vs. upper-field advantage. These visual field variations match those of low-level vision, indicating that higher-level face processing abilities either inherit or actively maintain the characteristic patterns of spatial selectivity found in early vision. The commonality of these spatial variations throughout the visual hierarchy means that the location of faces in our visual field systematically influences our perception of them.

Influence of back optic zone diameter on corneal morphology with orthokeratology lenses

ObjectiveThis study aimed to compare the changes in corneal morphological characteristics in corneal topography assessments performed after wearing orthokeratology (OK) lenses with different back optic zone diameters (BOZDs). These changes included the change ratios of the apical corneal power (ACP), the maximum relative corneal refractive power (mRCRP), and the treatment zone diameter (TZD). MethodsData from 133 children with myopia (average age 9.50 ± 1.23 years) treated at Fudan University Eye and Ear, Nose, and Throat Hospital were retrospectively analyzed. All participants wore the same brand of tangent-design OK lens (corneal refractive therapy, CRT). According to the BOZD, the patients were divided into two groups, of 5.0 and 6.0 mm BOZD, respectively. Corneal topography was analyzed at baseline, as well as 1 day, 1 week, and 1 month after wearing the lenses, and the change ratios of ACP, mRCRP, and TZD were compared between the two groups. ResultsThe change ratio of the ACP did not differ significantly between the BOZD 5.0 and 6.0 groups after 1 day or 1 week of lens wear (P = 0.170 and P = 0.113, respectively). However, after 1 month of lens wear, the change ratio of the ACP in the BOZD 5.0 group was significantly larger than that in the BOZD 6.0 group (P < 0.001). After 1 month of lens wear, the mRCRP along the horizontal and vertical meridians was higher (P < 0.05) and the TZD was significantly smaller (P < 0.001) in the BOZD 5.0 group than in the BOZD 6.0 group. ConclusionIn CRT OK lenses, a small BOZD lens can produce faster corneal shaping, a larger mRCRP, and a smaller TZD, which may have a better effect on slowing ocular axial length elongation. The lens parameters are also a factor affecting the TZD.

Observation on the tilt and decentration of multifocal intraocular lens with optic capture in Berger space for pediatric cataract.

This study aimed to observe the tilt and decentration of multifocal intraocular lens (IOL) with optic capture in Berger space within 2 years after pediatric cataract surgery. This is a prospective observational study. The implantation of multifocal IOL (Tecnis ZMB00) with optic capture in Berger space was performed on 33 patients (48 eyes) with pediatric cataract at Qingdao Eye Hospital. Tilt and decentration of IOL was measured using Scheimpflug system (Pentacam) at 1month and 2years postoperatively. All the multifocal IOLs were successfully implanted in Berger space with optic capture and no visually significant complications were detected during the follow-up. The mean tilt of IOLs was 2.779° ± 0.950° in the vertical plane and 2.399° ± 0.898° in the horizontal plane at 1month postoperatively, and the mean length of the decentration was 0.207 ± 0.081mm in vertical plane and 0.211 ± 0.090mm in the horizontal plane. Compared with 1month after surgery, the angle of tilt decreased by a mean of 0.192° and decentration increased by a mean of 0.014mm at the vertical meridian at 2 years postoperatively (P = 0.37 and P = 0.27, respectively), meanwhile, tilt increased by 0.265° and decentration increased by 0.012mm at the horizontal meridian (P = 0.11 and P = 0.22, respectively). The follow-up results suggest the tilt and decentration of multifocal IOL implantation with optic capture in Berger space remain stable in an acceptable range within 2years after cataract surgery in children above the age of 5. The study was approved by the Ethics Committee of Qingdao Eye Hospital, and registered on Chinese Clinical Trial Registry (ChiCTR identifier: 1900023155).

THREE-DIMENSIONAL RETINAL DISPLACEMENT BEFORE AND AFTER MACULAR PUCKER SURGERY.

To measure the coronal and sagittal retinal displacement before and after surgery for epiretinal membranes in InfraRed horizontal foveal sections and optical coherence tomography scans and describe displacement tridimensionality, vision loss, and metamorphopsia. Retrospective series with greater than 6-month average follow-up before and after surgery. The record included best-corrected visual acuity, optical coherence tomography, M-charts, and InfraRed retinography. Overall, pre- and postoperative coronal and sagittal retinal displacement across the entire field, concentric circles at 0.5-, 1.5-, and 4.5-mm radii, and the central horizontal and vertical meridian were calculated as the optical flow of consecutive images. This study comprised 10 patients (4 men, 6 women), with 22.7 ± 25.2 months follow-up before surgery and 16.2 ± 7.3 months after. Best-corrected visual acuity reduced before surgery (0.15 ± 0.67 logarithm of minimum angle of resolution to 0.38 ± 0.85 logarithm of minimum angle of resolution; P < 0.05) and increased afterward (0.086 ± 0.61 logarithm of minimum angle of resolution; P = 0.003). Preoperative coronal displacement was 30.1 ± 29.1 µm versus 67.0 ± 23.4 µm after (P = 0.002). Sagittal retinal displacement was 140.9 ± 84.6 µm before surgery, 339.7 ± 172.5 µm after (P = 0.017), and 357.6 ± 320.8 µm across the entire follow-up. Preoperative best-corrected visual acuity decreases correlated with the foveal coronal displacement. Vertical metamorphopsia correlated with the average coronal displacement within a 4.5-mm radius. Pre- and postoperative sagittal displacement correlated with horizontal metamorphopsia (P = 0.006 and P = 0.026). Postoperative sagittal displacement correlated with postoperative best-corrected visual acuity (P = 0.026) and foveal thickness (P = 0.009). This study confirms that postoperative displacement is greater than preoperative and that sagittal displacement is greater than coronal and correlates with best-corrected visual acuity and metamorphopsia changes.