Peripheral Ganglion Cell Complex Thickness and Retinal Microvasculature in Myopia Using Wide-Field Swept-Source OCT.

Purpose: This study aims to investigate the impact of axial elongation on ganglion cell complex thickness (GCCT) and retinal capillary density (CD) using wide-field swept-source optical coherence tomography angiography. Methods: A retrospective cross-sectional analysis was conducted involving 506 eyes. Fovea-centered scans were obtained to assess the subregional GCCT and capillary density across the whole retina, the superficial capillary plexus (SCP), and deep capillary plexus (DCP) among three groups: normal control, high myopia (HM) eyes with axial length < 28 mm, and HM eyes with axial length > 28 mm. Regional variations (central vs. peripheral, quadrants difference [superior, inferior, nasal, and temporal]) were analyzed. Results: In HM eyes with axial length > 28 mm, GCCT and retinal CD exhibit a general decline in most regions (P < 0.05). In HM eyes with axial length < 28 mm, significant reductions were observed specifically in peripheral regions, as in the GCCT beyond the 3 × 3 mm2 area and CD in the 9-12 mm whole retina, 9-12 mm superior SCP, and 6-12 mm DCP (P < 0.05). Maximum GCCT and retinal CD reduction with axial elongation was observed in subregions beyond 6 × 6  mm2. Conclusions: GCCT beyond the 3 × 3 mm2 area and peripheral retinal CD beyond the 6 × 6  mm2 area were more susceptible to axial elongation and are thereby deserving of particular attention. Translational Relevance: It is necessary to evaluate different regions during the clinical assessment of the effect of myopia on the fundus and pay close attention to the peripheral retina.

Automated eyeball volume measurement based on CT images using neural network-based segmentation and simple estimation.

With the increase in the dependency on digital devices, the incidence of myopia, a precursor of various ocular diseases, has risen significantly. Because myopia and eyeball volume are related, myopia progression can be monitored through eyeball volume estimation. However, existing methods are limited because the eyeball shape is disregarded during estimation. We propose an automated eyeball volume estimation method from computed tomography images that incorporates prior knowledge of the actual eyeball shape. This study involves data preprocessing, image segmentation, and volume estimation steps, which include the truncated cone formula and integral equation. We obtained eyeball image masks using U-Net, HFCN, DeepLab v3 +, SegNet, and HardNet-MSEG. Data from 200 subjects were used for volume estimation, and manually extracted eyeball volumes were used for validation. U-Net outperformed among the segmentation models, and the proposed volume estimation method outperformed comparative methods on all evaluation metrics, with a correlation coefficient of 0.819, mean absolute error of 0.640, and mean squared error of 0.554. The proposed method surpasses existing methods, provides an accurate eyeball volume estimation for monitoring the progression of myopia, and could potentially aid in the diagnosis of ocular diseases. It could be extended to volume estimation of other ocular structures.

Correlation in retinal thickness and macular retina plus choroidal microcirculation in pediatric myopia.

To analyze the relationship in retinal thickness, macula retina and choroidal microcirculation in pediatric patients with myopia. Pediatric patients with high myopia (high myopia group, n = 30, 60 eyes) and pediatric patients with low to moderate myopia (low myopia group, n = 30, 60 eyes) admitted to our hospital from January 2021 to January 2022 were randomly selected as the study subjects. Retinal thickness, the blood density of retina, and the blood density of the choroid were collected in each area of the macula by taking optical coherence tomography (OCT) and OCT angiography (OCTA). Pearson correlation analysis was conducted to compare the results from the 2 groups. Outer retinal thickness showed a weak positive correlation with Superficial vascular complex flow density (SVD) and deep vascular complex flow density (DVD) (P < .05), but no significant correlation with choroidal capillary density (P > .05); inner retinal thickness showed a weak positive correlation with SVD and DVD (P < .05), but no significant correlation with choroidal capillary density (P > .05). In pediatric patients with myopia, there is a positive correlation between the blood flow density of macular retina and retinal thickness, and the retinal thickness will become thinner with increasing myopia.

Parallel comparison of ocular metrics in non-human primates with high myopia by LS900, ultrasonography and MRI-based 3D reconstruction.

We investigate the ocular dimensions and shape by using Lenstar900 (LS900), A-scan ultrasonography, and Magnetic Resonance Imaging (MRI) in highly myopic Macaca fascicularis. The ocular dimensions data of LS900, A-scan ultrasonography and MRI was assessed from 8 eyes (4 adult male cynomolgus macaque) with extremely high myopia (≤-1000DS) and compared by means of coefficients of concordance and 95% limits of agreement. Multiple regression analysis was performed to explore the associations between ocular biometry, volume, refraction and inter-instrument discrepancies. Test-retest reliability of three measurements of ocular parameters at two time points was almost equal (intraclass correlation = 0.831 to 1.000). The parallel-forms reliability of three measurements was strong for vitreous chamber depth (VCD) (coefficient of concordance = 0.919 to 0.981), moderate for axial length (AL) (coefficient of concordance = 0.486 to 0.981), and weak for anterior chamber depth (ACD) (coefficient of concordance = 0.267 to 0.621) and lens thickness (LT) (coefficient of concordance = 0.035 to 0.631). The LS900 and MRI systematically underestimated the ACD and LT comparing to A-scan ultrasonography (P < 0.05). Notably, the average AL on LS900 displayed a significant correlation with those on MRI (r = 0.978, P < 0.001) and A-scan ultrasonography (r = 0.990, P < 0.001). Almost 4/5 eyeballs were prolate. The mean eyeball volume positively correlated with AL (r = 0.782, P = 0.022), the width (r = 0.945, P = 0.000), and the length (r = 0.782, P = 0.022) of eyeball, while negatively correlated with SER (r = -0.901, P = 0.000). In conclusion, there was a high inter-instrument concordance for VCD with LS900, A-scan ultrasonography and MRI, while ACD and LT were underestimated with LS900 compared to A-scan ultrasonography, and the LS900 and A-scan ultrasonography could reliably measure the AL. MRI further revealed an equatorial globe shape in extremely myopic non-human primates.

Clinical History Method versus Corneal Tomographers in Estimating Corneal Power after Photorefractive Surgery

AIMS: To investigate the concordance between the corneal power determined by various approaches with two tomographers (MS-39® and Galilei G6®) and the clinical history method (CHM) in patients undergoing photorefractive surgery with excimer laser for myopic errors. MATERIAL AND METHODS: Prospective cohort study. Patients undergoing keratorefractive surgery, and having pre- and postoperative keratometries, and tomographies, were included. RESULTS: In 90 eyes, the differences in the power estimated by the CHM and the one determined by four approaches with the corneal tomographers, which included measurements of the posterior cornea, did not show statistically significant differences in their averages. However, the 95% limits of agreement were very wide. After obtaining regression formulas to adjust the values of these four variables, the results of the agreement analysis were similar. CONCLUSION: Although certain values either directly determined or derived from measurements with the Galilei® and MS-39®corneal tomographers, approximated the estimated value of postoperative corneal power according to the CHM, due to the amplitude of their limits of agreement, these calculations must be taken with care, because they may not be accurate in a given eye.

Peripapillary atrophy area predicts the decrease of macular choroidal thickness in young adults during myopia progression.

OBJECTIVE: This study aimed to investigate the influence of peripapillary atrophy (PPA) area and axial elongation on the longitudinal changes in macular choroidal thickness (ChT) in young individuals with myopia. METHODS AND ANALYSIS: In this longitudinal investigation, 431 eyes-342 categorised as non-high myopia (non-HM) and 89 as HM-were examined for 2 years. Participants were examined with swept-source optical coherence tomography. The macular ChT, PPA area and axial length (AL) were measured at baseline and follow-up visits. Multiple regression analysis was performed to identify factors associated with ChT changes. The areas under the receiver operating characteristic curves were analysed to ascertain the predictive capacity of the PPA area and axial elongation for the reduction in macular ChT. RESULTS: Initial measurements revealed that the average macular ChT was 240.35±56.15 µm in the non-HM group and 198.43±50.27 µm in the HM group (p<0.001). It was observed that the HM group experienced a significantly greater reduction in average macular ChT (-7.35±11.70 µm) than the non-HM group (-1.85±16.95 µm, p=0.004). Multivariate regression analysis showed that a greater reduction of ChT was associated with baseline PPA area (ß=-26.646, p<0.001) and the change in AL (ß=-35.230, p<0.001). The combination of the baseline PPA area with the change in AL was found to be effective in predicting the decrease in macular ChT, with an area under the curve of 0.741 (95% CI 0.694 to 0.787). CONCLUSION: Over 2 years, eyes with HM exhibit a more significant decrease in ChT than those without HM. Combining the baseline PPA area with the change in AL could be used to predict the decrease of macular ChT.

Evaluation and comparison of optical coherence tomography angiography (OCTA) parameters in normal and moderate myopic individuals.

OBJECTIVE: The objective of this study was to evaluate and compare Optical Coherence Tomography Angiography (OCTA) parameters in patients with moderate myopia and healthy individuals retrospectively. METHODS: A total of 80 male individuals aged 18-20 years were included in the study with 40 moderate myopic and 40 healthy persons. All participants underwent detailed ocular examination including refraction, intraocular pressure (IOP), visual acuity, biomicroscopy, OCTA measurement and optic biometry measurement. Retinal, retinal nerve fiber layer and choroidal layer thicknesses were evaluated in µm with the help of the software available in the OCTA device. RESULTS: The mean axial length (24.32 ± 0.53 mm) was statistically significantly higher in the moderate myopic group (24.32 mm) compared to the healthy group (23.33 ± 0.61 mm) (p < 0.001). Spherical equivalent (SE) was found as -3.79 ± 0.91 D in the moderate myopic group and -0.22 ± 0.32 D in the healthy group (p < 0.05). The mean superficial foveal mean density (FovSupMVD) and the mean deep foveal mean density (FovDepMVD) were statistically significantly lower in the moderate myopic group than in the healthy group (both, p < 0.001). The mean retinal temporal thickness (RTt) was statistically significantly lower in the moderate myopic group (p = 0.017). There was a mild negative correlation between axial length and FovSupMVD, FovDepMVD in myopes. In axial length ROC analysis, the cutoff value for moderate myopes was found to be 24.15 mm. Mean superficial foveal mean density (FovSupMVD) and mean deep foveal mean density (FovDepMVD), mean retinal temporal thickness (RTt) were significantly lower in the group above 24.15 mm axial length compared to the group below 24.15 mm axial length (all three, p < 0.001). Foveal avascular zone was significantly higher in the group above 24.15 mm axial length (p = 0.016) CONCLUSION: The results of our study indicate that the mean axial length and spherical equivalent were significantly higher, while retinal temporal thickness, the mean superficial foveal mean density and the mean deep foveal mean density were significantly lower in patients with myopia up to -6.0 D compared to the healthy individuals.

Diagnostic performance of wide-field optical coherence tomography angiography for high myopic glaucoma.

Diagnosing and monitoring glaucoma in high myopic (HM) eyes are becoming very important; however, it is challenging to diagnose this condition. This study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (WF-OCTA) maps for the detection of glaucomatous damage in eyes with HM and to compare the diagnostic ability of WF-OCTA maps with that of conventional imaging approaches, including swept-source optical coherence tomography (SS-OCT) wide-field maps. In this retrospective observational study, a total 62 HM-healthy eyes and 140 HM eyes with open-angle glaucoma were included. Patients underwent a comprehensive ocular examination, including SS-OCT wide-field and 12 × 12 WF-OCTA scans. The WF-OCTA map represents the peripapillary and macular superficial vascular density maps. Glaucoma specialists determined the presence of glaucomatous damage in HM eyes by reading the WF-OCTA map and comparing its sensitivity and specificity with those of conventional SS-OCT images. The sensitivity and specificity of 12 × 12 WF-OCTA scans for HM-glaucoma diagnosis were 87.28% and 86.94%, respectively, while, the sensitivity and specificity of SS-OCT wide-field maps for HM-glaucoma diagnosis were 87.49% and 80.51%, respectively. The specificity of the WF-OCTA map was significantly higher than that of the SS-OCT wide-field map (p < 0.05). The sensitivity of the WF-OCTA map was comparable with that of the SS-OCT wide-field map (p = 0.078). The WF-OCTA map showed good diagnostic ability for discriminating HM-glaucomatous eyes from HM-healthy eyes. As a complementary method to an alternative imaging modality, WF-OCTA mapping can be a useful tool for the detection of HM glaucoma.

Biometry-Based Technique for Determining the Anterior Scleral Thickness: Validation Using Optical Coherence Tomography Landmarks.

Purpose: Considering the potential role of anterior scleral thickness (AST) in myopia and the ubiquitous use of optical biometers, we applied and validated a biometry-based technique for estimating AST using optical coherence tomography (OCT) landmarks. Methods: The AST was determined across four meridians in 62 participants (aged 20-37 years) with a swept-source OCT and a noncontact optical biometer at a mean ± SD distance of 3.13 ± 0.88 mm from the limbus. The biometer's graticule was focused and aligned with the anterior scleral reflex, which led to the generation of four prominent A-scan peaks: P1 (anterior bulbar conjunctiva), P2 (anterior episclera), P3 (anterior margin of anterior sclera), and P4 (posterior margin of anterior sclera), which were analyzed and compared with the corresponding OCT landmarks to determine tissue thickness. Results: The AST measurements between biometer and OCT correlated for all meridians (r ≥ 0.70, overall r = 0.82; coefficient of variation [CV], 9%-12%; P < 0.01). The mean difference ± SD between two instruments for overall AST measures was 3 ± 2.8 µm (range, -18 to +16 µm; lower limits of agreement, -89 to +83 µm; P = 0.23) across all meridians. The mean ± SE AST with both instruments was found to be thickest at the inferior (562 ± 7 µm and 578 ± 7 µm) and thinnest at the superior (451 ± 7 µm and 433 ± 6 µm) meridian. The biometer demonstrated good intrasession (CV, 8.4%-9.6%) and intersession (CV, 7.9%-13.3%) repeatability for AST measurements across all meridians. Conclusions: The noncontact optical biometer, which is typically used to determine axial length, is capable of accurately estimating AST based on OCT landmarks. Translational Relevance: The high-resolution optical biometers can demonstrate wider application in the field of myopia research and practice to determine AST.

Prediction of Myopia Eye Axial Elongation With Orthokeratology Treatment via Dense I2I Based Corneal Topography Change Analysis.

While orthokeratology (OK) has shown effective to slow the progression of myopia, it remains unknown how spatially distributed structural stress/tension applying to different regions affects the change of corneal geometry, and consecutive the outcome of myopia control, at fine-grained detail. Acknowledging that the underlying working mechanism of OK lens is essentially mechanics induced refractive parameter reshaping, in this study, we develop a novel mechanics rule guided deep image-to-image learning framework, which densely predicts patient's corneal topography change according to treatment parameters (lens geometry, wearing time, physiological parameters, etc.), and consecutively predicts the influence on eye axial length change after OK treatment. Encapsulated in a U-shaped multi-resolution map-to-map architecture, the proposed model features two major components. First, geometric and wearing parameters of OK lens are spatially encoded with convolutions to form a multi-channel input volume/tensor for latent encodings of external stress/tension applied to different regions of cornea. Second, these external latent force maps are progressively down-sampled and injected into this multi-scale architecture for predicting the change of corneal topography map. At each feature learning layer, we formally derive a mathematic framework that simulates the physical process of corneal deformation induced by lens-to-cornea interaction and corneal internal tension, which is reformulated into parameter learnable cross-attention/self-attention modules in the context of transformer architecture. A total of 1854 eyes of myopia patients are included in the study and the results show that the proposed model precisely predicts corneal topography change with a high PSNR as 28.45dB, as well as a significant accuracy gain for axial elongation prediction (i.e., 0.0276 in MSE). It is also demonstrated that our method provides interpretable associations between various OK treatment parameters and the final control effect. Our project code package is available at https://github.com/Rongdingyi/PhyIntNet.

Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography.

PURPOSE: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects. METHODS: Cross-sectional study that included 34 high myopic patients (≥ -6 diopters [D]), 90 emmetropes (-1 to +1 D) and 38 hyperopic patients (≥ +3.5 D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3 mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated. RESULTS: The dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P < .001). However, there were no differences between high myopes and emmetropes for any of the parameters (P ≥ .076) except for the CMT at 3 mm in the temporal quadrant (P < .001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P > .05). CONCLUSIONS: The SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction.

Characteristics of ciliary muscle profile in high myopes measured by swept-source anterior segment optical coherence tomography.

OBJECTIVE: To characterize and compare the ciliary muscle thickness (CMT) between low and high myopes using swept-source anterior segment optical coherence tomography (AS-OCT). METHODS: Forty visually healthy young Chinese adults aged 18-25 years were divided into two groups based on refractive errors: low myopia (n = 20, spherical-equivalent refractive error (SER) between -0.50 D to -3.00 D) and high myopia (n = 20, SER ≤ -6.00 D). Cycloplegic refractions were performed before axial length (AL) and CMT were measured using a partial coherence laser interferometer and an AS-OCT respectively. CMT was measured perpendicularly to the sclera-ciliary muscle interface at 1 mm (CMT_1), 2 mm (CMT_2), and 3 mm (CMT_3) posterior to the scleral spur, and at the location with maximal thickness (CMT_MAX). RESULTS: High myopes demonstrated thicker CMT at 2 mm (CMT_2, p = 0.035) and 3 mm (CMT_3, p = 0.003) posterior to the scleral spur, but thinner maximal CMT (CMT_MAX, p = 0.005) than low myopes. The apical CMT_1 and CMT_MAX were also thinner in high myopes than in low myopes (both p< 0.001). CMT_MAX, apical CMT_1, and apical CMT_MAX correlated directly with SER and inversely with AL; in contrast, CMT_2 and CMT_3 showed inverse correlations with SER but direct correlations with AL. CONCLUSION: Our findings revealed significant differences in CMT between low and high myopes, with high myopes showing thicker CMT at 2 mm and 3 mm posterior to the scleral spur, but thinner maximal CMT. These results provide new evidence of the potential structural differences in ciliary muscles during myopia development and progression.

Characteristics of the Peripapillary Structure and Vasculature in Patients With Myopic Anisometropia.

Purpose: To evaluate the interocular differences of the peripapillary structural and vascular parameters and that of association with axial length (AL) in participants with myopic anisometropia using swept-source optical coherence tomography. Methods: This prospective cross-sectional study included 90 eyes of 45 participants. Each participant's eyes were divided into the more and less myopic eye respectively according to spherical equivalent. The ß- and γ-parapapillary atrophy (PPA) areas, Bruch's membrane opening distance, border length, and border tissue angle were measured manually. Peripapillary choroidal vascularity index and choroidal thickness (CT) values in superior, nasal, inferior, and temporal were calculated using a custom-built algorithm based on MATLAB. Results: The interocular difference in AL and spherical equivalent was 0.62 ± 0.26 mm and -1.50 (-2.13, -1.25) diopters (D), respectively. The interocular difference in spherical equivalent was highly correlated with that of the AL. The ß- and γ-PPA areas were significantly greater in more myopic eyes. The mean and inferior peripapillary choroidal vascularity index and all regions of peripapillary CT were significantly lower in the more myopic eyes. The interocular difference in AL was significantly positively correlated with the interocular differences in γ-PPA area and border length and negatively correlated with the interocular differences in temporal choroidal vascularity index and mean, inferior, and temporal peripapillary CT. There was an independent correlation between the interocular differences in AL and the interocular differences in γ-PPA area, inferior, and temporal peripapillary CT. Conclusions: Significant differences between both groups were detected in most peripapillary parameters, especially in peripapillary CT. The γ-PPA area, border length, and peripapillary CT were significantly correlated with the elongation of AL. Translational Relevance: The current study characterized and analyzed the peripapillary parameters in myopic anisometropia, which helped to monitor myopic progression.

Poster Session: Optical coherence elastography for In situ measurement of stiffness increase in posterior sclera after crosslinking.

During eye growth, scleral development critically determine eye size and thus the refractive status of the eye. Scleral remodeling in myopia includes scleral thinning, loss of scleral tissue, and weakening of the mechanical properties. Therefore, an intervention aiming at stiffening scleral tissues (crosslinking, SCXL) may provide a way to prevent or treat myopia. The development of SCXL requires tools to evaluate the effects of crosslinking on the mechanical properties of tissues, particularly in sclera where the mechanical properties are more spatially heterogeneous than in the cornea, anisotropic, and varying locally from the anterior to posterior regions. Here, we apply the high-frequency OCE technique to measure the heterogeneous mechanical properties of posterior scleral tissues and, evaluate the changes in shear moduli after SCXL. As a model system, we use ex vivo in porcine eyes and riboflavin-assisted UV crosslinking. From measured elastic wave speeds (6-16kHz), the average out-of-plane shear modulus was 0.71±0.12MPa (n=20) for normal scleras. After treatment, the shear modulus increased to 1.50±0.39MPa. This 2-fold change was consistent with the increase of static Young's modulus from 5.5±.1 to 9.3±1.9MPa after crosslinking, using conventional uniaxial extensometry. OCE revealed regional stiffness differences across the temporal, nasal, and deeper posterior sclera, demonstrating its potential as a noninvasive tool to test the effect of scleral crosslinking.

Poster Session: Experimental assessment of scleral anisotropy using multi-meridian air-coupled ultrasonic optical coherence elastography.

Scleral biomechanics plays a key role in the understanding of myopia progression. In this study, we characterized the elastic properties of sclera using an air-coupled ultrasonic (ACUS) optical coherence elastography (OCE) system. New Zealand rabbit eyes (n=7) were measured (<24hr postmortem) in four scleral locations: superior/inferior temporal (ST, IT), and superior/inferior nasal (SN, IN) maintaining an intraocular pressure of 15 mmHg. Elastic waves were induced in the sclera, and wave propagation velocity and shear modulus were measured along two directions: circumferential (superior-inferior) and meridional (nasal-temporal). Wave velocity in scleral tissue ranged from 6 to 24 m/s and shear modulus from 11 to 150 kPa. Velocity was significantly higher (p<.001) in the circumferential vs. meridional directions in the following locations: ST:15.83±2.85 vs 9.43±1.68 m/s, IT:15.00±3.98 vs 8.93±1.53 m/s; SN:16.79±4.30 vs 9.27±1.47 m/s; and IN:13.92±3.85 vs 8.57±1.46 m/s. The average shear modulus in the circumferential was also significantly higher (p<.001) than in the meridional direction for all locations: 65.37±6.04 vs 22.55±1.36 kPa. These results show that the rabbit sclera is mechanically anisotropic with higher rigidity in the circumferential direction compared to the meridional direction. ACUS-OCE is a promising non-invasive method to quantify the biomechanical changes in scleral tissue for future studies involving myopia treatments.

Poster Session: Estimation of scleral biomechanical properties from air-puff-coupled optical coherence tomography.

Progression of myopia is usually accompanied by axial overgrowth of the eyeball, which affects scleral biomechanics (BM). To study scleral biomechanics, we propose the use of air-puff deformation swept-source OCT imaging. Air-puff deformation imaging was performed at different sites of ex vivo porcine (n=5) and rabbit (n=3) eyes, (<24hr postmortem): Nasal/temporal equatorial and posterior sclera (NE, NP, TE, TP), superior (S) and inferior (I) sclera, and cornea (C). Intraocular pressure was kept at 15mmHg. Deformation data were used as input to inverse finite element model (FEM) algorithms to reconstruct BM properties. Experimental deformation amplitudes showed dependence on the animal model, with porcine scleras exhibiting greater inter-site variation (displacement of S, I was up to four times greater than that of N, T), while rabbit scleras exhibited at most 40% of displacement differences between all sites. Both models showed significant (p<.001) differences in the temporal deformation profile between sclera and (C), but similarities in all scleral locations, suggesting that the scleral temporal profile is independent of scleral thickness variations. The FEM estimated an elastic modulus of 1.84 ± 0.30 MPa (I) to 6.04 ± 2.11 MPa (TE) for the porcine sclera. The use of scleral air-puff imaging is promising for noninvasive investigation of structural changes in the sclera associated with myopia and for monitoring possible modulation of scleral stiffness with myopia treatment.

Performance of neuroretinal rim thickness measurement by Cirrus high-definition optical coherence tomography in myopic eyes.

Neuroretinal rim (NRR) measurement can aid the diagnosis of glaucoma. A few studies reported that Cirrus optical coherence tomography (OCT) had NRR segmentation errors. The current study investigated segmentation success of NRR in myopic eyes using the Cirrus built-in software and to determine the number of acquisitions required to identify NRR thinning. Right eye of 87 healthy adult myopes had an optic disc scanned using Cirrus HD-OCT for five successive acquisitions. A masked examiner evaluated 36 radial line images of each scan to screen for segmentation errors using the built-in software at the Bruch's membrane opening (BMO) and/or internal limiting membrane (ILM). Participants with three accurate NRR acquisitions had their average NRR thickness determined. This result was compared with average of the two acquisitions and the first acquisition. Among 435 OCT scans of the optic disc (87 eyes × 5 acquisitions), 129 (29.7%) scans had segmentation errors that occurred mainly at the ILM. The inferior-temporal and superior meridians had slightly more segmentation errors than other meridians, independent of axial length, amount of myopia, or presence of peripapillary atrophy. Sixty-five eyes (74.7%) had at least three accurate NRR measurements. The three acquisitions had high reliability in NRR thickness in the four quadrants (intraclass correlation coefficient > 0.990, coefficient of variation < 3.9%). NRR difference between the first acquisition and the average of three acquisitions was small (mean difference 2 ± 13 µm, 95% limits of agreement within ± 30 µm) among the four quadrants. Segmentation errors in NRR measurements appeared regardless of axial length, amount of myopia, or presence of peripapillary atrophy. Cirrus segmentation lines should be manually inspected when measuring NRR thickness.

Macular Imaging Characteristics in Children with Myelinated Retinal Nerve Fiber and High Myopia Syndrome.

Objectives: To investigate the macular imaging features in patients with unilateral myelinated retinal nerve fiber (MRNF) and high myopia syndrome. Materials and Methods: Six patients with unilateral MRNF and high myopia syndrome and 13 myopic controls were enrolled in this study. Spectral domain (SD) optical coherence tomography (OCT), SD enhanced depth imaging OCT, and OCT angiography (OCTA) imaging results of MRNF-affected eyes were compared with the fellow eyes and myopic controls. Results: All patients had abnormal foveal reflex and/or ectopia. No significant difference in retinal thickness parameters were noted between the groups. In OCT scans, posterior vitreous detachment (PVD) was observed in 4 out of the 6 MRNF-affected eyes. Regarding OCTA parameters, only a significant increase in acircularity index was noted in myelinated eyes (p=0.01). Conclusion: All patients demonstrated normal foveal contours, macular structure, and OCTA features except for a higher acircularity index. The incidence of PVD was notably increased in the myelinated eyes.

Posterior scleral birefringence measured by triple-input polarization-sensitive imaging as a biomarker of myopia progression.

In myopic eyes, pathological remodelling of collagen in the posterior sclera has mostly been observed ex vivo. Here we report the development of triple-input polarization-sensitive optical coherence tomography (OCT) for measuring posterior scleral birefringence. In guinea pigs and humans, the technique offers superior imaging sensitivities and accuracies than dual-input polarization-sensitive OCT. In 8-week-long studies with young guinea pigs, scleral birefringence was positively correlated with spherical equivalent refractive errors and predicted the onset of myopia. In a cross-sectional study involving adult individuals, scleral birefringence was associated with myopia status and negatively correlated with refractive errors. Triple-input polarization-sensitive OCT may help establish posterior scleral birefringence as a non-invasive biomarker for assessing the progression of myopia.

Development of a deep learning system to detect glaucoma using macular vertical optical coherence tomography scans of myopic eyes.

Myopia is one of the risk factors for glaucoma, making accurate diagnosis of glaucoma in myopic eyes particularly important. However, diagnosis of glaucoma in myopic eyes is challenging due to the frequent associations of distorted optic disc and distorted parapapillary and macular structures. Macular vertical scan has been suggested as a useful tool to detect glaucomatous retinal nerve fiber layer loss even in highly myopic eyes. The present study was performed to develop and validate a deep learning (DL) system to detect glaucoma in myopic eyes using macular vertical optical coherence tomography (OCT) scans and compare its diagnostic power with that of circumpapillary OCT scans. The study included a training set of 1416 eyes, a validation set of 471 eyes, a test set of 471 eyes, and an external test set of 249 eyes. The ability to diagnose glaucoma in eyes with large myopic parapapillary atrophy was greater with the vertical than the circumpapillary OCT scans, with areas under the receiver operating characteristic curves of 0.976 and 0.914, respectively. These findings suggest that DL artificial intelligence based on macular vertical scans may be a promising tool for diagnosis of glaucoma in myopic eyes.