Vertical Meridian Research Articles

The Mechanism of Macular Sparing.

Patients with homonymous hemianopia sometimes show preservation of the central visual fields, ranging up to 10°. This phenomenon, known as macular sparing, has sparked perpetual controversy. Two main theories have been offered to explain it. The first theory proposes a dual representation of the macula in each hemisphere. After loss of one occipital lobe, the back-up representation in the remaining occipital lobe is postulated to sustain ipsilateral central vision in the blind hemifield. This theory is supported by studies showing that some midline retinal ganglion cells project to the wrong hemisphere, presumably driving neurons in striate cortex that have ipsilateral receptive fields. However, more recent electrophysiological recordings and neuroimaging studies have cast doubt on this theory by showing only a minuscule ipsilateral field representation in early visual cortical areas. The second theory holds that macular sparing arises because the occipital pole, where the macula is represented, remains perfused after occlusion of the posterior cerebral artery because it receives collateral flow from the middle cerebral artery. An objection to this theory is that it cannot account for reports of macular sparing in patients after loss of an entire occipital lobe. On close scrutiny, such reports turn out to be erroneous, arising from inadequate control of fixation during visual field testing. Patients seem able to detect test stimuli on their blind side within the macula or along the vertical meridian because they make surveillance saccades. A purported treatment for hemianopia, called vision restoration therapy, is based on this error. The dual perfusion theory is supported by anatomical studies showing that the middle cerebral artery perfuses the occipital pole in many individuals.In patients with hemianopia from stroke, neuroimaging shows preservation of the occipital pole when macular sparing is present. The frontier dividing the infarcted territory of the posterior cerebral artery and the preserved territory of the middle cerebral artery is variable, but always falls within the representation of the macula, because the macula is so highly magnified. For physicians, macular sparing was an important neurological sign in acute hemianopia because it signified a posterior cerebral artery occlusion. Modern neuroimaging has supplanted the importance of that clinical sign but at the same time confirmed its validity. For patients, macular sparing remains important because it mitigates the impact of hemianopia and preserves the ability to read fluently.

Retinal Differential Light Sensitivity Variation Across the Macula in Healthy Subjects: Importance of Cone Separation and Loci Eccentricity.

PurposeMicroperimetry measures differential light sensitivity (DLS) at specific retinal locations. The aim of this study is to examine the variation in DLS across the macula and the contribution to this variation of cone distribution metrics and retinal eccentricity.MethodsForty healthy eyes of 40 subjects were examined by microperimetry (MAIA) and adaptive optics imaging (rtx1). Retinal DLS was measured using the grid patterns: foveal (2°–3°), macular (3°–7°), and meridional (2°–8° on horizontal and vertical meridians). Cone density (CD), distribution regularity, and intercone distance (ICD) were calculated at the respective test loci coordinates. Linear mixed-effects regression was used to examine the association between cone distribution metrics and loci eccentricity, and retinal DLS.ResultsAn eccentricity-dependent reduction in DLS was observed on all MAIA grids, which was greatest at the foveal-parafoveal junction (2°–3°) (−0.58 dB per degree, 95% confidence interval [CI]; −0.91 to −0.24 dB, P < 0.01). Retinal DLS across the meridional grid changed significantly with each 1000 cells/deg2 change in CD (0.85 dB, 95% CI; 0.10 to 1.61 dB, P = 0.03), but not with each arcmin change in ICD (1.36 dB, 95% CI; −2.93 to 0.20 dB, P = 0.09).ConclusionsWe demonstrate significant variation in DLS across the macula. Topographical change in cone separation is an important determinant of the variation in DLS at the foveal-parafoveal junction. We caution the extrapolation of changes in DLS measurements to cone distribution because the relationship between these variables is complex.Translational RelevanceCone density is an independent determinant of DLS in the foveal-parafoveal junction in healthy eyes.

Comparison of Changes in Eye Findings of Premenopausal and Postmenopausal Women

ObjectivesThis study aimed to compare the presence of blepharitis, ocular tension (OT) with corneal thickness, refractive values and ocular axial length changes in premenopausal and postmenopausal women.Materials and methodsThyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), oestradiol (E2), refractive values with prolactin, refractions in horizontal and vertical meridians, OT values, ocular axial length, central corneal thickness and the presence of blepharitis were evaluated in 153 premenopausal patients and 142 postmenopausal patients.ResultsStatistically significant differences were found for the values for right eye OT (P < 0.001), left eye OT (P < 0.001) and presence of blepharitis. There appears to be no relationship between corneal refractive values corneal thickness or ocular axial length.ConclusionsWoman in postmenopausal period should be examined by ophthalmologist because of the significant increase in blepharitis and OT.

Influence of the “Inverted U Method” Nd: YAG Laser Posterior Capsulotomy on Anterior Segment Parameters, Decentration and Tilt of Intraocular Lens in Patients after Phaco-vitrectomy

ABSTRACT Purpose To investigate the effects of the “inverted U method” Nd:YAG laser posterior capsulotomy on anterior segment parameters, decentration and tilt of intraocular lens (IOLs) and visual acuity in posterior capsular opacification (PCO) patients after combined phaco-vitrectomy. Methods Seventy-six patients (76 eyes) were enrolled in this study, who were diagnosed as PCO and underwent “inverted U method” Nd:YAG laser posterior capsulotomy. All patients had undergone previous combined phaco-vitrectomy for rhegmatogenous retinal detachment. The parameters including IOL decentration, angle of IOL tilt, anterior chamber angle (ACA), anterior chamber depth (ACD), anterior chamber volume (ACV), central corneal thickness (CCT), keratometry, pupil size, axial length (AL), intraocular pressure (IOP), refractive status, corrected distance visual acuity (CDVA), objective scattering index (OSI) and Chinese version of Visual Function 14 (VF-14) index were obtained before and 3 months after capsulotomy. Results After capsulotomy, the tilt angle and decentration of the IOLs at both vertical (tilt: p = .004, decentration: p = .029) and horizontal meridian (tilt: p = .001, decentration: p = .017) were significantly decreased, ACA increased (p = .015), CDVA (p = .000), VF-14 score (p = .000) and OSI (p = .000) were significantly improved. There were a significant decrease in cylindrical error (p = .001) and a myopic shift in spherical error (p = .001) after the capsulotomy. No significant differences in ACD, ACV, CCT, keratometry, pupil size, AL and IOP were detected (p > .05 for all). Conclusion The “inverted U method” Nd: YAG laser posterior capsulotomy decreases tilt and decentration of the IOL, increases ACA and causes no change in ACD, ACV, CCT and IOP in patients after phaco-vitrectomy. These changes make a decrease in cylindrical error and a myopic shift in spherical error. Laser capsulotomy significantly improves visual acuity.

Sleep does not aid the generalisation of binocular disparity-based learning to the other visual hemifield.

Visual perceptual learning refers to long-lasting performance improvements on a visual skill - an ability supported by plastic changes in early visual brain areas. Visual perceptual learning has been shown to be induced by training and to benefit from consolidation during sleep, presumably via the reactivation of learning-associated neuronal firing patterns. However, previous studies have almost exclusively relied on a single paradigm, the texture discrimination task, on which performance improvements may rely on higher-order rather than lower-level perceptual skills. In the present study, we tested whether sleep has beneficial effects on a visual disparity discrimination task. We confirm previous findings in showing that the ability to discriminate different disparities is unaffected by sleep during a 12-hr retention period after training. Importantly, we extend these results by providing evidence against an effect of sleep on the generalisation of improved disparity discrimination across the vertical meridian. By relying on a between-subject design, we further exclude carry-over effects as a possible confound present in previous findings. These data argue against sleep as an important factor in the consolidation of a low-level perceptual skill. This sets important constraints on models of the role of sleep and sleep-associated neural reactivation in the consolidation of non-declarative memories.

Studying Spatial Visual Attention: The Attention-Window Task as a Measurement Tool for the Shape and Maximum Spread of the Attention Window

Visual attentional processes have been an important topic in psychological research for years. Over the last few decades, new methods have been developed, aiming to explore the characteristics of the focus of attention in more detail. Studies that applied the “Attention-Window Task” (AWT) quantified the maximum extent of the “Attention Window” (AW) along its horizontal, vertical, and diagonal meridians, when subjects were required to perceive two peripheral stimuli simultaneously. In three experiments using the AWT, we investigated the effects of cue validity (Experiment 1), stimulus-onset asynchrony (SOA) (i.e., the interval between the onset of the cues and the onset of the target stimuli), and target stimuli complexity (Experiment 3) on the size and shape of the AW. Results showed that the AW was greater under valid cue conditions compared to invalid conditions, when the locations of cue and target stimuli differed. Furthermore, the AW decreased when the SOA between the cue and targets was reduced and also when the task complexity was higher and more objects within the target stimuli had to be classified. Overall, it can be stated that the AWT with its possible task changes and adjustments can be considered as a potential standard tool to measure the maximum spread and shape of the spatial AW.

Crossed–uncrossed projections from primate retina are adapted to disparities of natural scenes

In mammals with frontal eyes, optic-nerve fibers from nasal retina project to the contralateral hemisphere of the brain, and fibers from temporal retina project ipsilaterally. The division between crossed and uncrossed projections occurs at or near the vertical meridian. If the division was precise, a problem would arise. Small objects near midline, but nearer or farther than current fixation, would produce signals that travel to opposite hemispheres, making the binocular disparity of those objects difficult to compute. However, in species that have been studied, the division is not precise. Rather, there are overlapping crossed and uncrossed projections such that some fibers from nasal retina project ipsilaterally as well as contralaterally and some from temporal retina project contralaterally as well as ipsilaterally. This increases the probability that signals from an object near vertical midline travel to the same hemisphere, thereby aiding disparity estimation. We investigated whether there is a deficit in binocular vision near the vertical meridian in humans and found no evidence for one. We also investigated the effectiveness of the observed decussation pattern, quantified from anatomical data in monkeys and humans. We used measurements of naturally occurring disparities in humans to determine disparity distributions across the visual field. We then used those distributions to calculate the probability of natural disparities transmitting to the same hemisphere, thereby aiding disparity computation. We found that the pattern of overlapping projections is quite effective. Thus, crossed and uncrossed projections from the retinas are well designed for aiding disparity estimation and stereopsis.

Agreement Between Angle-to-Angle Distance and Aqueous Depth Obtained With Two Different Optical Coherence Tomographers and a Scheimpflug Camera.

To compare angle-to-angle (ATA) distance and aqueous depth (AQD) readings produced by two different optical coherence tomography (OCT) devices and a Scheimpflug camera. ATA distance and AQD were measured in 60 eyes using the Visante time-domain OCT (TD-OCT) (Carl Zeiss Meditec AG), the Anterion swept-source OCT (SS-OCT) (Heidelberg Engineering GmbH), and the Pentacam HR Scheimpflug camera (Oculus Optikgeräte GmbH). Moreover, ATA distance was measured along the horizontal and vertical meridians. Bland-Altman analysis was used to assess the agreement between devices. All three devices did not yield similar horizontal ATA distance: 11.96 ± 0.47 mm (TD-OCT), 11.96 ± 0.42 mm (SS-OCT), and 11.05 ± 0.52 mm (Pentacam). More specifically, the Pentacam yielded significantly smaller values (approximately 0.9 mm, P < .001). Mean vertical ATA distance was 12.61 ± 0.65 and 12 ± 0.65 mm for the TD-OCT and SS-OCT, respectively (P = .983). Vertical ATA distance was significantly larger than horizontal ATA distance for both OCT devices (approximately 0.6 mm, P < .001). The lowest mean difference was found between both OCT devices (0.0068 and -0.0415 mm, for horizontal and vertical meridians, respectively) and the highest between the Pentacam and the two OCT devices (approximately 0.9 mm). As for AQD, inter-device mean values were also statistically significant: 2.89 ± 0.48, 2.82 ± 0.49, and 2.79 ± 0.50 mm, for the TD-OCT, SS-OCT, and Pentacam, respectively (P < .001). Mean differences were similar for the TD-OCT versus SS-OCT and SS-OCT versus Pentacam (approximately 0.02 mm), and larger between the TD-OCT and Pentacam (approximately 0.05 mm). The results show that the TD-OCT and SS-OCT are interchangeable instruments for ATA distance measurement but the Pentacam is not with either of the two OCT devices. A clinical criterion should assess whether these three devices could be used interchangeably for AQD measurement. [J Refract Surg. 2021;37(2):133-140.].

Color appearance of small stimuli presented in central and near peripheral visual fields

AbstractThis study investigates the change in the color appearance of a small stimulus with a diameter of 0.5° presented at various locations along the vertical and horizontal meridians in the visual field. To determine the color appearance, the hue and saturation judgment method and the categorical color naming method were used. The results obtained using these two methods at 0° exhibit the same quality of color appearance as that of a stimulus with a diameter of about 2° reported in previous studies. A more rapid decrease in perceived saturation and hue shift toward yellow in reddish and greenish stimuli are indicated in the hue and saturation judgment, whereas early distinction of “red” and persistence of “yellow” and “blue” responses are observed in the categorical color naming method. Despite the evident change in color appearance for each stimulus, the relationship between the responses obtained by the two methods for all stimuli was approximately the same across the visual field examined here. The unique hue component needed to elicit the color name of “yellow,” “green,” or “blue” is nearly constant along the eccentricity. However, the hue component of “red” is significantly higher than that of the other primary colors, especially at 0°, which suggests the specificity of that color.

Asymmetries in visual acuity around the visual field.

Human vision is heterogeneous around the visual field. At a fixed eccentricity, performance is better along the horizontal than the vertical meridian and along the lower than the upper vertical meridian. These asymmetric patterns, termed performance fields, have been found in numerous visual tasks, including those mediated by contrast sensitivity and spatial resolution. However, it is unknown whether spatial resolution asymmetries are confined to the cardinal meridians or whether and how far they extend into the upper and lower hemifields. Here, we measured visual acuity at isoeccentric peripheral locations (10 deg eccentricity), every 15° of polar angle. On each trial, observers judged the orientation (± 45°) of one of four equidistant, suprathreshold grating stimuli varying in spatial frequency (SF). On each block, we measured performance as a function of stimulus SF at 4 of 24 isoeccentric locations. We estimated the 75%-correct SF threshold, SF cutoff point (i.e., chance-level), and slope of the psychometric function for each location. We found higher SF estimates (i.e., better acuity) for the horizontal than the vertical meridian and for the lower than the upper vertical meridian. These asymmetries were most pronounced at the cardinal meridians and decreased gradually as the angular distance from the vertical meridian increased. This gradual change in acuity with polar angle reflected a shift of the psychometric function without changes in slope. The same pattern was found under binocular and monocular viewing conditions. These findings advance our understanding of visual processing around the visual field and help constrain models of visual perception.

Assessment of a software guided system to reduce pre-existing astigmatism in cataract surgery.

The aim of this pilot study was to assess the astigmatism after small incision cataract surgery by use of a novel software guided surgical technique. The software system guides the surgeon toward a hypothetical shape of the cornea. When this shape is achieved, the vertical meridian is relaxed and the incision does not produce any astigmatism. How that hypothetical shape is to be achieved by the surgeon is described. If preoperative astigmatism exists, the hypothetical shape calculated by the system takes that into account. This enables the surgeon to reduce preexisting astigmatism, without having to change the site or size of the standard 6 mm 12 o clock incision of SICS. Results: Results indicated that preoperative astigmatism reduced in 11 out of 14 cases at the end of 8 weeks, remained unchanged in one, and increased by less than 0.5D in two cases. This proves the hypothesis that the vertical corneal meridian is under higher tension and relaxing it by flattening the perpendicular meridian has a reducing effect on postoperative astigmatism.

Discovery of Meridian Entities and the Third Regulatory Framework

Human diseases are the result of neuromodulation and humoral regulation disorders. However, the Chinese people have carried out acupuncture experiments on the body for thousands of years, and their curative effects have convinced them that the meridians and acupoint structure based on acupuncture and moxibustion is not a simple mechanism of nerve conduction and humoral regulation. This study adopts Xu's pulse diagnosis Intangible Cultural Heritage Inheritance technology. According to Lingshu · the pulse on the skin surface of the whole body was perceived. Pulse diagnosis found that there were longitudinal and transverse pulsating thin lines on the body surface. Then through the meridian pen to test the vertical and horizontal conduction path, acupuncture to verify the clinical effect, and local anatomy to confirm the existence of meridian and acupoint entities in the human body. Finally, it is determined that there are 31 pairs of transverse meridians and 13 pairs of longitudinal meridians in human epidermis and dermis. It is highly consistent with the meridian path of the twelve meridians, the odd meridians and the eight meridians of traditional Chinese medicine, and the position of acupoints is also highly consistent. According to the new development of skin anatomy, this paper expounds the physiological and pathological regulation mechanism of meridian structure, and determines that there is an artificial external regulation system based on vertical and horizontal meridian structure in human body.

Микроструктура внутриполушарных восходящих путей в экстрастриарные поля коры кошки

To study the microstructure of intrahemispheric connections between cortical areas of different hierarchical levels, horseradish peroxidase was microionophoretically injected into the vertical columns of areas 19, 21a. Retrogradely labeled cells in areas 17 and 18 were identified and reconstructed on the unfolded cortical surface. It was found that the columns of areas 19, 21a, in addition to the inputs from the zones of contralateral visual hemifield projection in areas 17, 18, also receive afferentation from the transition zone 17/18, which partly represents ipsilateral hemifield. The distance between these zones of afferentation depended on the distance of the injected column from the projection of the central vertical meridian of the visual field and coincided with the visual projection maps of areas 17, 18. Revealed changes in the position of afferent cells in the transition zone 17/18 were also dependent on the azimuth of the columns. It indicates the transition zone 17/18 division into two retinotopically ordered subzones related to areas 17 and 18. It is assumed that the convergence of inputs from areas 17, 18 makes it possible for the neurons of areas 19, 21a to tune for more complex features in the configuration of images and the spatial location of objects in comparison with neurons in areas 17, 18.

Presaccadic Attention Enhances Contrast Sensitivity, But Not at the Upper Vertical Meridian

Presaccadic Attention Enhances Contrast Sensitivity, But Not at the Upper Vertical Meridian

Power profiles of centre-distance multifocal soft contact lenses.

Centre-distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined. Three centre-distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from -1.00D to -6.00D in 1D steps were stored in ISO 18369-3:2017 standard phosphate buffered saline for 24h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer-reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One-way anova with Tukey's HSD post-hoc t-tests were used to analyse maximum add power by lens design. Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6mm radius), intermediate zone (about 1.6mm radius to 2.1mm) and near zone (about 2mm radius to 4mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7mm. From 2.7mm to 3.0mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32±0.44D), then Proclear D (+1.84±0.28D) and Biofinity D (+1.47±0.34D) MFCLs (all p<0.04). Add power peaked at different locations for different lens powers and designs. Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.

Cortical Distance but Not Physical Distance Modulates Attentional Rhythms.

It has been well documented that the spotlight of attention is intrinsically rhythmic and oscillates by discretely sampling either single or multiple objects. However, the neural site of attentional rhythms remains poorly understood. Considering the topography of visual cortical areas, we modulated the cortical distances of two gratings while fixing the corresponding retinal distance by setting the gratings on different sides (cortically far, Experiment 1) or on the same side (cortically near, Experiment 2) of the vertical median, to investigate the interhemispheric divide effect in attentional rhythms. The cue-target stimulus onset asynchrony (SOA) varied from 0.1 s to 1.08 s in 20-ms increments, allowing fluctuations below 50 Hz to be examined. The results showed that when the two stimuli were on opposite sides of the vertical meridian, attentional rhythms were observed at theta and alpha frequencies, consistent with the results reported in previous studies. However, when the two stimuli were located on the same side of the vertical meridian, attentional rhythms were not observed. This study indicates that attentional rhythms are modulated by cortical distance but not by physical distance.

Wide-field choroidal vascular analysis in central serous chorioretinopathy.

To report the wide-field choroidal vessel analysis in central serous chrorioretinopathy (CSCR) and their fellow eyes. Wide-field optical coherence tomography (WF-OCT) images (55°) were obtained using Spectralis HRA + OCT (Heidelberg Engineering, Germany) in extremes of gazes in all quadrants and manual montages were created to obtain wide field images up to equator. Choroidal thickness (CT), large choroidal vessel layer thickness (LCVT), and choroidal vascularity index (CVI) were calculated in macular segment (twice the disc to fovea distance) and all four quadrants. Regression analysis was performed to identify the factors influencing CVI. Thirty-one patients of CSCR including 39 eyes of CSCR (32 chronic, 7 acute) and 23 fellow eyes were analyzed. CT and LCVT were significantly higher in submacular choroid than all extramacular segments in both CSCR and fellow eyes (all p values <0.01). CVI varied significantly in different segments in horizontal (p < 0.01 in both) and vertical meridian (p < 0.01 and p = 0.01 respectively) in CSCR and fellow eyes. Both CSCR and fellow eyes had highest CVI in nasal segment with minimum CVI in macular segment. Age (p = 0.85), gender (p = 0.39), chronicity of the disease (acute vs chronic, p = 0.57), axial length (p = 0.67), SBP (p = 0.81), and DBP (p = 0.94) were not significantly correlated to CVI. CVI shows significant regional variation with macular segment showing the lowest CVI whereas nasal segments have highest CVI in both CSCR and their fellow eyes. On the contrary, submacular segment has highest CT and LCVT with taper towards periphery in both CSCR and fellow eyes.

Stimulus-dependent contrast sensitivity asymmetries around the visual field.

Asymmetries in visual performance at isoeccentric locations are well-documented and functionally important. At a fixed eccentricity, visual performance is best along the horizontal, intermediate along the lower vertical, and poorest along the upper vertical meridian. These performance fields are pervasive across a range of visual tasks, including those mediated by contrast sensitivity. However, contrast performance fields have not been characterized with a systematic manipulation of stimulus spatial frequency, eccentricity, and size; three parameters that constrain contrast sensitivity. Further, individual differences in performance fields measurements have not been assessed. Here, we use an orientation discrimination task to characterize the pattern of contrast sensitivity across four isoeccentric locations along the cardinal meridians, and to examine whether and how this asymmetry pattern changes with systematic manipulation of stimulus spatial frequency (4 cpd to 8 cpd), eccentricity (4.5 degrees to 9 degrees), and size (3 degrees visual angle to 6 degrees visual angle). Our data demonstrate that contrast sensitivity is highest along the horizontal, intermediate along the lower vertical, and poorest along the upper vertical meridian. This pattern is consistent across stimulus parameter manipulations, even though they cause profound shifts in contrast sensitivity. Eccentricity-dependent decreases in contrast sensitivity can be compensated for by scaling stimulus size alone. Moreover, we find that individual variability in the strength of performance field asymmetries is consistent across conditions. This study is the first to systematically and jointly manipulate, and compare, contrast performance fields across spatial frequency, eccentricity, and size, and to address individual variability in performance fields.

Relationship between Three-Dimensional Magnetic Resonance Imaging Eyeball Shape and Optic Nerve Head Morphology

To determine if the 3-dimensional (3D) eyeball shape is associated with the positions of the central retinal vascular trunk (CRVT) and the externally oblique border (EOB) in the optic nerve head (ONH). Prospective, cross-sectional study. Fifty-six subjects (112 eyes) with a diagnosis of glaucoma or glaucoma suspect. The eyeball shape on 3D magnetic resonance imaging (MRI) scans was classified according to the dimension of the longest diameter: axial dimension (prolate sphere), group 1; horizontal dimension (horizontally oblate sphere), group 2; and vertical dimension (vertically oblate sphere), group 3. The deviation of the CRVT, as a surrogate of lamina cribrosa (LC) shift, was measured from the center of the Bruch's membrane opening (BMO) demarcated by OCT imaging, with the horizontal midline as 0° and the superior location as a positive value. The angular location of the longest EOB was also measured. Positions of CRVT and EOB according to the 3D eyeball shape. Among 112 eyes, 54 (48%) had a prolate shape (group 1), 23 (21%) had a horizontally oblate shape (group 2), and 35 (31%) had a vertically oblate shape (group 3). The angular deviation of the CRVT differed among the groups: to the nasal side in group 1, to the temporal side in group 2, and along the vertical meridian in group 3. In cases of asymmetric eyeball shape, the CRVT was deviated toward the undergrown side from the overgrown side, regardless of grouping. The angular location of the longest EOB was in the direction opposite to the CRVT position (P < 0.001). A generalized estimating equation analysis revealed that the temporal location of the CRVT was associated with older age (P= 0.001), nasal location of the longest EOB (P < 0.001), and oblate shape of the eyeball (P < 0.001, group 2; P= 0.007, group 3). The position of the CRVT and EOB were associated with the 3D eyeball shape. Considering that infant ONH morphology is highly uniform, various modes of eyeball expansion during growth can result in diverse directionalities of offset between the LC and the BMO in adults.

Manipulation of Front-Surface Profile of Scleral Contact Lenses to Alter Peripheral Refraction

The front optic zone diameter of scleral contact lenses was manipulated to mimic the central treatment zone induced by orthokeratology contact lens wear, to explore potential effects on the peripheral refraction profile. The purpose of this study was to investigate effects on the peripheral refraction profile of changing front optic zone diameters of scleral contact lenses. Twelve young adults were fitted with scleral contact lenses (diameter, 16.5 mm) with two front optic zone diameters (6 and 4 mm) on one eye only on 2 separate days. Both lenses were fabricated with front optic zone power of -3.00 D and plano power outside the optic zone to mimic the orthokeratology treatment effect. All lenses had the same spherical back-surface design with a toric lens periphery. Peripheral refraction was measured at 10° increments along horizontal (±35°) and vertical (±30°) meridians before lens insertion and after 10 minutes of lens wear. Mixed-model analysis and post hoc t tests with Bonferroni correction were performed. Compared with baseline, no significant change in relative spherical equivalent refraction M was observed with 6-mm optic zone lenses along the horizontal meridian. However, a significant difference in relative M profile was found with 4-mm optic zone lenses (P = .009). M became myopic at all locations in the nasal visual field (P < .05) except at 35°. In contrast, compared with baseline, no significant changes in relative M were found with either 6- or 4-mm optic zone lenses along the vertical meridian. The greater myopic shift in relative peripheral refraction with 4-mm compared with 6-mm front optic zone lenses suggests that a reduced treatment zone diameter in orthokeratology may induce more myopic peripheral refraction changes. This may guide us toward novel orthokeratology lens designs for more effective myopia control.