Retinal Microvascular Network and Microcirculation Assessments in High Myopia

Optical Coherence Tomography Angiography Compared With Optical Coherence Tomography for Detection of Early Glaucoma With High Myopia

Purpose: To investigate the diagnostic abilities of the perfusion density (PD) and structural thickness parameters in the peripapillary and macular regions measured by optical coherence tomography angiography (OCTA) and optical coherence tomography (OCT) and to test if their diagnostic abilities of early glaucoma are different between highly myopic (HM) and non-highly myopic (NHM) patients. Methods: A total of 75 glaucoma patients and 65 controls were included in the analyses. The glaucoma detection abilities of macular PD and peripapillary PD, along with macular ganglion cell-inner plexiform layer (mGCIPL) thickness and peripapillary retinal nerve fiber layer (pRNFL) thicknesses were compared between the HM and NHM group. Diagnostic ability was assessed by area under the receiver operating characteristics (AUC) curves, adjusted by age, axial length, and signal strength. Results: The diagnostic ability of macular PD and mGCIPL thickness had no significant difference in both HM and NHM groups. However, the diagnostic ability of peripapillary PD except in the temporal section was significantly lower in the HM group than in the NHM group (all p < 0.05). The diagnostic ability of the superior, nasal, and average pRNFL thickness was also significantly lower in the HM group than in the NHM group (all p < 0.05). Conclusion: This study demonstrated that although peripapillary PD and macular PD were both significantly reduced in patients with highly myopia, the diagnostic ability of peripapillary PD in HM patients was significantly lower than that in NHM patients, while macular PD was not. Macular OCTA along with OCT imaging should be included in the imaging algorithm in early glaucoma diagnosis in highly myopic patients.

Assessment of optic nerve vascularity in healthy eyes using superb microvascular imaging: a preliminary study

BACKGROUND

Changes in optic nerve vascularity are observed in many diseases. Superb microvascular imaging (SMI) has the potential to become the method of choice for detecting microvasculature in the optic nerves.

PURPOSE

To evaluate optic nerve vascularity in healthy individuals through power Doppler sonography (PDUS) and SMI.

MATERIAL AND METHODS

Twenty-seven healthy patients with 54 eyes were prospectively evaluated. The duration of the examination for optic nerve vascularity lasted until the posterior ciliary artery blood supply was observed in PDUS and SMI. The visibility of vascularity, as well as the ratio of the vascular structures to the optic nerves (vascular index [VI]), was evaluated.

RESULTS

Fifty-four eyes were evaluated from a total of 27 patients (mean age = 49.0 ± 19.42 years). The VI value for the right optic nerve was 29.58 ± 4.00 while for the left optic nerve, it was 31.21 ± 3.52. Vascularity was clearly observed in both eyes (n = 54) in all 27 cases in the evaluation performed with the SMI technique. However, with the power Doppler examination, vascular flow was not observed in 14 right eyes and in 10 left eyes within the specified timeframe.

CONCLUSION

The results indicate that imaging of vascular structures can be done faster and better with SMI than PDUS examination. The normal VI values may provide important information about the blood supply of the optic nerve, which is of relevance in orbital pathologies and many systemic conditions.

Morphological characteristics of retinal vessels in eyes with high myopia: Ultra-wide field images analyzed by artificial intelligence using a transfer learning system

Purpose

The purpose of this study is to investigate the retinal vascular morphological characteristics in high myopia patients of different severity.

Methods

317 eyes of high myopia patients and 104 eyes of healthy control subjects were included in this study. The severity of high myopia patients is classified into C0-C4 according to the Meta Analysis of the Pathologic Myopia (META-PM) classification and their vascular morphological characteristics in ultra-wide field imaging were analyzed using transfer learning methods and RU-net. Correlation with axial length (AL), best corrected visual acuity (BCVA) and age was analyzed. In addition, the vascular morphological characteristics of myopic choroidal neovascularization (mCNV) patients and their matched high myopia patients were compared.

Results

The RU-net and transfer learning system of blood vessel segmentation had an accuracy of 98.24%, a sensitivity of 71.42%, a specificity of 99.37%, a precision of 73.68% and a F1 score of 72.29. Compared with healthy control group, high myopia group had smaller vessel angle (31.12 ± 2.27 vs. 32.33 ± 2.14), smaller fractal dimension (Df) (1.383 ± 0.060 vs. 1.424 ± 0.038), smaller vessel density (2.57 ± 0.96 vs. 3.92 ± 0.93) and fewer vascular branches (201.87 ± 75.92 vs. 271.31 ± 67.37), all P < 0.001. With the increase of myopia maculopathy severity, vessel angle, Df, vessel density and vascular branches significantly decreased (all P < 0.001). There were significant correlations of these characteristics with AL, BCVA and age. Patients with mCNV tended to have larger vessel density (P < 0.001) and more vascular branches (P = 0.045).

Conclusion

The RU-net and transfer learning technology used in this study has an accuracy of 98.24%, thus has good performance in quantitative analysis of vascular morphological characteristics in Ultra-wide field images. Along with the increase of myopic maculopathy severity and the elongation of eyeball, vessel angle, Df, vessel density and vascular branches decreased. Myopic CNV patients have larger vessel density and more vascular branches.

Association Between Types of Posterior Staphyloma and Refractive Error After Cataract Surgery for High Myopia

Purpose: To investigate the association between different types of posterior staphyloma (PS) and refractive error (RE) after cataract surgery in patients with high myopia.

Methods: This retrospective study included 113 eyes of 113 highly myopic patients with PS. PS was detected using a wide-field fundus imaging system. PS was classified into wide macular, narrow macular, and other types. RE equaled the actual spherical equivalent (SE) minus the targeted SE values 3 months after cataract surgery.

Results: The rates of wide macular, narrow macular, and other types of PS were 46.02, 39.82, and 14.16%, respectively. There were no significant differences in best corrected distance visual acuity (BCDVA) or SE among the three classifications of PS before cataract surgery (P > 0.05). However, postoperative BCDVA and SE were significantly different among the three types of PS patients (P < 0.05). The average RE values were 0.98 ± 1.00 D, 0.19 ± 0.87 D, 0.13 ± 0.59 D, respectively; the statistical differences of RE were <0.01, <0.01, and 0.81 (wide macular vs. narrow macular, wide macular vs. other types, narrow macular vs. other types), respectively. Multivariate linear regression analysis revealed that higher hyperopia RE after surgery was associated with wide macular staphyloma (P < 0.001), more myopic SE (P = 0.003), and increased BCDVA (P = 0.002) before surgery.

Conclusions: Wide macular PS may be associated with more hyperopic RE; it may serve as a critical biomarker of hyperopic RE after cataract surgery in highly myopic patients.

Long-term repeatability of peripapillary optical coherence tomography angiography measurements in healthy eyes

This is a prospective observational study to establish the short- and long-term repeatability of measurements of peripapillary optical coherence tomography angiography (OCTA) parameters in healthy eyes and identify factors affecting long-term repeatability. We enrolled 84 healthy eyes. Participants with a history of any ophthalmic disease (except high myopia) or intraocular surgery were excluded from the study. An experienced examiner performed OCTA using disc-centered 6 × 6 mm scans. All examinations were conducted twice at 5-min intervals at the initial visit and repeated at least 6 months later. For short-term repeatability, the coefficient of variation (CV) was 2.94–4.22% and the intraclass correlation coefficient (ICC) was 0.840–0.934. For long-term repeatability, the CV was 2.73–3.84% and the ICC was 0.737–0.934. Multivariate analyses showed that the axial length (AL) (B = 0.970; p = 0.002) and mean signal strength (SS) (B = − 2.028; p < 0.001) significantly affected long-term repeatability. Measurements of peripapillary OCTA parameters exhibited excellent short-term and good long-term repeatability in healthy individuals. The mean SS and AL affected long-term repeatability and should be considered while interpreting peripapillary OCTA images.

Longitudinal Macular Retinal and Choroidal Microvasculature Changes in High Myopia

Purpose

The purpose of this study was to determine the longitudinal changes in macular retinal and choroidal microvasculature in normal healthy and highly myopic eyes.

Methods

Seventy-one eyes, including 32 eyes with high myopia and 39 healthy control eyes, followed for at least 12 months and examined using optical coherence tomography angiography imaging in at least 3 visits, were included in this study. Fovea-centered 6 × 6 mm scans were performed to measure capillary density (CD) of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC). The rates of CD changes in both groups were estimated using a linear mixed model.

Results

Over a mean 14-month follow-up period, highly myopic eyes exhibited a faster rate of whole image CD (wiCD) loss (−1.44%/year vs. −0.11%/year, P = 0.001) and CD loss in the outer ring of the DCP (−1.67%/year vs. –0.14%/year, P < 0.001) than healthy eyes. In multivariate regression analysis, baseline axial length (AL) was negatively correlated with the rate of wiCD loss (estimate = −0.27, 95% confidence interval [CI] = −0.48 to −0.06, P = 0.012) and CD loss in the outer ring (estimate = −0.33, 95% CI = −0.56 to −0.11, P = 0.005), of the DCP. The CD reduction rates in the SCP and CC were comparable in both groups (all P values > 0.05).

Conclusions

The rate of CD loss in the DCP is significantly faster in highly myopic eyes than in healthy eyes and is related to baseline AL. The CD in the outer ring reduces faster in eyes with longer baseline AL.

Age-related changes in the fractal dimension of the retinal microvasculature, effects of cardiovascular risk factors and smoking behaviour

Purpose

This cross‐sectional study investigates the association between retinal vessel complexity and age and studies the effects of cardiovascular health determinants.

Methods

Retinal vessel complexity was assessed by calculating the box‐counting fractal dimension (D_f) from digital fundus photographs of 850 subjects (3–97 years). All photographs were labelled as ‘non‐pathological’ by the treating ophthalmologist.

Results

Statistical models showed a significantly decreasing relationship between age and D_f (linear: R‐squared = 0.1897, p < 0.0001; quadratic: R‐squared = 0.2343, p < 0.0001; cubic: R‐squared = 0.2721, p < 0.0001), with the cubic regression model offering the best compromise between accuracy and model simplicity. Multivariate cubic regression showed that age, spherical equivalent and smoking behaviour have an effect (p < 0.0001) on D_f. A significantly increasing effect of the number of pack‐years on D_f was observed (effect: 0.0004, p = 0.0017), as well as a significantly decreasing effect of years since tobacco abstinence (effect: −0.0149, p < 0.0001).

Conclusion

We propose using a cubic trend with age, refractive error and smoking behaviour when interpreting retinal vessel complexity.

Prediction of Cardiovascular Parameters With Supervised Machine Learning From Singapore "I" Vessel Assessment and OCT-Angiography: A Pilot Study

Purpose

Assessment of cardiovascular risk is the keystone of prevention in cardiovascular disease. The objective of this pilot study was to estimate the cardiovascular risk score (American Hospital Association [AHA] risk score, Syntax risk, and SCORE risk score) with machine learning (ML) model based on retinal vascular quantitative parameters.

Methods

We proposed supervised ML algorithm to predict cardiovascular parameters in patients with cardiovascular diseases treated in Dijon University Hospital using quantitative retinal vascular characteristics measured with fundus photography and optical coherence tomography – angiography (OCT-A) scans (alone and combined). To describe retinal microvascular network, we used the Singapore “I” Vessel Assessment (SIVA), which extracts vessel parameters from fundus photography and quantitative OCT-A retinal metrics of superficial retinal capillary plexus.

Results

The retinal and cardiovascular data of 144 patients were included. This paper presented a high prediction rate of the cardiovascular risk score. By means of the Naïve Bayes algorithm and SIVA + OCT-A data, the AHA risk score was predicted with 81.25% accuracy, the SCORE risk with 75.64% accuracy, and the Syntax score with 96.53% of accuracy.

Conclusions

Performance of these algorithms demonstrated in this preliminary study that ML algorithms applied to quantitative retinal vascular parameters with SIVA software and OCT-A were able to predict cardiovascular scores with a robust rate. Quantitative retinal vascular biomarkers with the ML strategy might provide valuable data to implement predictive model for cardiovascular parameters.

Translational Relevance

Small data set of quantitative retinal vascular parameters with fundus and with OCT-A can be used with ML learning to predict cardiovascular parameters.

Retinal microvascular and neuronal function in patients with multiple sclerosis: 2-year follow-up

OBJECTIVE

To determine the longitudinal changes in retinal microstructure, microvasculature, microcirculation, and axonal and neuronal functions in patients with relapsing-remitting multiple sclerosis (RRMS) over the time course of about two years.

METHODS

A total of 30 patients (60 eyes) with RRMS were followed for a period of 27 ± 6 months and evaluated with a battery of clinical tests including low contrast letter acuity (LCLA), intraretinal layer thicknesses by optical coherence tomography (OCT), ganglion cell function by steady-state pattern electroretinography (PERG), axonal function by polarization-sensitive OCT, volumetric vessel density (VVD) by OCT angiography, and retinal tissue perfusion (RTP) by retinal function imager.

RESULTS

Axonal function measured as retinal nerve fiber layer birefringence in the temporal quadrant and vessel density in the deep vascular plexus were significantly decreased at 2-year follow-up (P < 0.05). Subgroup analyses showed that the increased retinal blood flow volume occurred in patients with no evidence of disease activity (NEDA), and with stable or improved visual function (P < 0.05). There was no significant difference in the expanded disability state scale, LCLA, RTP, VVD, or PERG measures between the two visits (P > 0.05).

CONCLUSION

To our best knowledge, this is the first 2-year prospective comprehensive study with a detailed assessment of retinal microstructure and neuronal functions in patients with RRMS. The recovery of retinal microcirculation occurred in patients with NEDA, and stable or improved visual function, suggesting these measurements as potential imaging biomarkers for monitoring disease progression.

Induced Refractive Error Changes the Optical Coherence Tomography Angiography Transverse Magnification and Vascular Indices

PURPOSE

To assess the effect of changing anterior eye refractive power with contact lenses on the transverse magnification of en face images and associated vascular indices from optical coherence tomographic angiography (OCT-A).

DESIGN

Prospective crossover study.

METHODS

Spherical soft contact lenses (-6 diopter [D] to +6 D in 2 D steps) were used to induce anterior eye refractive power changes in 11 healthy young adults and 3 × 3-mm macular scans were captured using OCT-A (Zeiss AngioPlex, software version 11.0; Cirrus HD-OCT 5000, Carl Zeiss Meditec Inc). Image transverse magnification was predicted based on refraction and biometry measurements and compared with empirical changes in the en face images measured with image analysis. Linear regression analysis was performed to assess the relationship between induced refractive ametropia and foveal avascular zone (FAZ) area, perimeter, circularity, and vessel density and perfusion density.

RESULTS

The predicted transverse magnification was linearly related to induced refractive ametropia and to the empirical transverse magnification changes (average slope: 1.02, 95% CI: 0.90-1.34). All the OCT-A indices showed linear relationships with induced refractive ametropia (P < .05) with the 12 D tested range altering the indices by 7% to 12%. After correcting for transverse magnification, all OCT-A indices except FAZ area were linearly related to induced refractive ametropia (P < .05) and were reduced to 1% to 9%.

CONCLUSIONS

This study is the first to show that induced refractive ametropia can affect OCT-A image magnification and indices. These changes are clinically important and need to be considered along with biometry effects when interpreting OCT-A indices. Transverse magnification changes can affect the ability of OCT-A to precisely measure linear dimensions of blood vessels.

Macular density alterations in myopic choroidal neovascularization and the effect of anti-VEGF on it

AIM

To analyse macular microvascular alterations in myopic choroidal neovascularization (mCNV) and the efficiency of anti-vascular endothelial growth factor (anti-VEGF) therapy for mCNV by optical coherence tomography angiography (OCTA).

METHODS

A total of 123 patients were included in this retrospective study, divided into mCNV group, high myopia (HM) group, and normal group at the Affiliated Eye Hospital of Wenzhou Medical University from January 2017 to January 2019. Superficial vessel density, deep capillary density, foveal avascular zone (FAZ) area, A-circularity index (AI) and vessel density around the 300 µm width of the FAZ region density (FD) and the area of choroidal neovascularization (CNV) lesion (only for mCNV group) were measured on 3×3 mm² OCTA images. FAZ area was corrected for axial length. Central macular thickness (CMT) was measured on OCT in mCNV group. Compared the parameters on OCTA of 3 groups and pre-anti-VEGF and post-anti-VEGF at 1, 2, 3, and 6mo follow-up in mCNV group.

RESULTS

There were significant differences among 3 groups in superficial vessel density, deep capillary density and FD (P<0.05). FAZ area in HM group was smaller than normal group (P<0.05), but there was no significant difference between mCNV group and the other two group. AI increased in mCNV group (P<0.05). The mean CMT, area and flow area of CNV lesion decreased after treatment (P<0.05), while vessel density and FAZ didn't change. The mean CMT, area and flow area of CNV lesion statistically decreased after anti-VEGF treatment in mCNV group (P<0.05), while superficial vessel density, deep capillary density and FAZ area, AI and FD didn't change. The mean reduction ratio of lesions was 50.32% (7.07% to 100%). Lesion regression 100% was observed in 2 cases (4.88%). There was a negative correlation between the CNV lesion area and reduction ratio (r=-0.380, P=0.042) and the flow lesion area and reduction ratio (r=-0.402, P=0.030).

CONCLUSION

Macular vessel density decreases, FAZ turns smaller and more irregular in mCNV eyes. Anti-VEGF therapy is efficient for mCNV without affecting vessel density and FAZ, but it is unable to completely eliminate CNV lesions in most cases. The bigger mCNV lesions have lower reduction ratio.

Structural and haemodynamic properties of ocular vasculature in axial myopia

The high prevalence of myopia has become a global concern, especially in East and Southeast Asia. Alarmingly, the prevalence of high myopia is increasing. Mechanical stretching caused by excessive eyeball elongation leads to various anatomical changes in the fundus. This stretching force may also lead to the development of vascular abnormalities, which tend to be subtle and easily overlooked. A healthy ocular vasculature is a prerequisite of adequate oxygen supply for normal retinal functions. This review summarises previous findings on structural and haemodynamic aspects of myopia-related vascular changes.

Evaluation of retinal vascular density and related factors in youth myopia without maculopathy using OCTA

To evaluate the retinal vascular flow density changes of myopic eyes of young adults using optical coherence tomography angiography and the factors affecting these changes. In this cross-sectional study, 90 eyes of 45 participants were analyzed and divided into three groups: mild, moderate, and high myopia (without pathological changes). Macular and radial peripapillary capillary flow densities were measured using optical coherence tomography angiography. Their relationships with the axial length, the spherical equivalent of the refractive error, and age were analyzed using analysis of variance, Pearson's correlation coefficient, and multivariate linear regression analysis. Superficial and deep macular vascular densities were significantly decreased in the high myopia group compared to the other groups. In the high myopia group, the nasal peripapillary flow density decreased, whereas the flow density inside the disc increased. The axial length negatively correlated with the superficial and deep macular vascular density, but positively correlated with the vascular density inside the disc. The spherical equivalent of the refractive error negatively correlated with the macular vascular density. The retinal vascular density decreased in the high myopia group. Hence, the microvascular network inside the disc may have a compensatory action in the hypoxic setting of high myopia.

TREND database: Retinal images of healthy young subjects visualized by a portable digital non-mydriatic fundus camera

Topological characterization of the Retinal microvascular nEtwork visualized by portable fuNDus camera (TREND) is a database comprising of 72 color digital retinal images collected from the students of the Faculty of Medicine at the University of Montenegro, in the period from February 18th to March 11th 2020. The database also includes binarized images of manually segmented microvascular networks associated with each raw image. The participant demographic characteristics, health status, and social habits information such as age, sex, body mass index, smoking history, alcohol use, as well as previous medical history was collected. As proof of the concept, a smaller set of 10 color digital fundus images from healthy older participants is also included. Comparison of the microvascular parameters of these two sets of images demonstrate that digital fundus images recorded with a hand-held portable camera are able to capture the changes in patterns of microvascular network associated with aging. The raw images from the TREND database provide a standard that defines normal retinal anatomy and microvascular network geometry in young healthy people in Montenegro as it is seen with the digital hand-held portable non-mydriatic MiiS HORUS Scope DEC 200.This knowledge could facilitate the application of this technology at the primary level of health care for large scale telematic screening for complications of chronic diseases, such as hypertensive and diabetic retinopathy. In addition, it could aid in the development of new methods for early detection of age-related changes in the retina, systemic chronic diseases, as well as eye-specific diseases. The associated manually segmented images of the microvascular networks provide the standard that can be used for development of automatic software for image quality assessment, segmentation of microvascular network, and for computer-aided detection of pathological changes in retina. The TREND database is freely available at https://doi.org/10.5281/zenodo.4521043.

Transient reduction in the retinal microvascular network following implantation surgery of implantable collamer lens: An OCT angiography study

Purpose

To evaluate changes in the retinal microvascular network after posterior chamber phakic implantable collamer lens (ICL) surgery using optical coherence tomography angiography (OCTA) in patients with high myopia.

Methods

Patients with high myopia who underwent ICL surgery were enrolled in this study. All patients underwent comprehensive ophthalmologic exams preoperatively and 1 week, 1 month, and 3 months postoperatively. The vascular densities (VDs) in the retina and the superficial and deep capillary plexuses of different annular and quadrantal areas were evaluated from OCTA images (Zeiss Cirrus 5000). Correlations between the variations in microvascular density and possible factors were further analyzed.

Results

The study comprised 32 eyes of 32 patients. The mean age of the patients was 26.91±7.610 years (15 men and 17 women). A statistically significant reduction in microvascular density in the retina and the superficial plexus was found 1 week and 1 month postoperatively (p<0.05, repeated-measures ANOVA). Further fractal analysis found that the VD of the outer ring declined statistically significantly (p<0.05). A statistically significant decrease was also found in the inferior nasal sector 1 week postoperatively, with an overall decrease in all four quadrants 1 month postoperatively. The microvascular density recovered toward the baseline level 3 months postoperatively. No correlations were observed between the variation in microvascular density and the spherical equivalent (SE), axial length (AL), intraocular pressure (IOP), amplitude of accommodation (AA), or contrast sensitivity.

Conclusions

Retinal microvascular density was decreased postoperatively and then recovered toward the baseline level after 3 months. ICL surgery may have a transient influence on the retinal microvascular network without affecting visual function.

Longer Axial Length Potentiates Relationship of Intraocular Pressure and Peripapillary Vessel Density in Glaucoma Patients

Purpose

The purpose of this study was to investigate how axial length (AL) changes the relationship of intraocular pressure (IOP) with peripapillary vessel density (pVD) in glaucoma versus non-glaucomatous eyes.

Methods

A population-based, cross-sectional study of 2127 African Americans aged 40 years and older in Inglewood, California, were imaged with 6 × 6-mm optic disc optical coherence tomography angiography scans. There were 1028 healthy subjects (1539 eyes) and 65 subjects with glaucoma (86 eyes) who met inclusion criteria. A multivariable linear mixed effects regression model investigated the relationship of IOP on pVD after controlling for signal strength, retinal nerve fiber layer thickness, and age. These results were stratified by AL groups.

Results

Higher IOP was a significant predictor of lower pVD among subjects with glaucoma (P = 0.009), but not among healthy subjects (P = 0.26). After stratifying by the sample median AL (23.46 mm), higher IOP was associated with lower pVD among subjects with glaucoma with longer AL (≥ 23.46 mm, P = 0.005), but not among those in the shorter AL (< 23.46 mm, P = 0.45). IOP was not significantly associated with pVD among healthy subjects in either AL stratum.

Conclusions

Among subjects with glaucoma with longer AL, IOP was significantly associated with pVD. This relationship was not seen among subjects with glaucoma with shorter AL or non-glaucomatous subjects in either AL group. These findings support the hypothesis that disturbed retinal autoregulation may be present in subjects with glaucoma with longer AL. Longitudinal studies are needed to further investigate whether axial elongation increases glaucoma risk by compromising retinal autoregulation.

Assessing the Use of Incorrectly Scaled Optical Coherence Tomography Angiography Images in Peer-Reviewed Studies: A Systematic Review

Importance

Individual differences in axial length affect the lateral magnification of in vivo retinal images and as a result can affect the accuracy of quantitative measurements made from these images. As measurements from optical coherence tomography angiography (OCTA) images are becoming increasingly used in the diagnosis and monitoring of a wide range of diseases, evaluating which studies use correctly scaled images is crucial to their interpretation.

Objective

To perform a systematic literature review to assess the percentage of articles that report correcting the scale of their OCTA images for individual differences in retinal magnification.

Evidence Review

A PubMed (MEDLINE) search was conducted for articles on OCTA retinal imaging published between June 1, 2015, and June 1, 2018. Initial results included 7552 articles. Initial exclusion criteria removed studies of animal models, as well as reviews, letters, replies, comments, and image-based or photographic essays. Articles not written in English and those that required purchase from non-English language websites were excluded. Articles that did not use OCTA for imaging the retina were also excluded. Remaining articles were reviewed in detail to assess whether the OCTA measurements required correct lateral scaling, and if so, whether axial length was reported or used to scale the images. We also determined the number of articles that mentioned the lack of correct lateral scaling as a limitation of the study.

Findings

A total of 989 articles were included in the detailed review. Of these, 509 were determined to require correct image scaling for their analyses, but only 41 (8.0%) report measuring and using axial length to correct the lateral scale of their OCTA images. Furthermore, of the 468 articles that did not correctly scale their images, only 18 (3.8%) mentioned this as a limitation to their study.

Conclusions and Relevance

These findings suggest that most peer-reviewed articles in PubMed that use quantitative OCTA measurements use incorrectly scaled images. This could call into question the conclusions of such studies and warrants consideration by OCTA manufacturers, physicians, authors, journal reviewers, and journal editors.

Macular Microvasculature in High Myopia without Pathologic Changes: An Optical Coherence Tomography Angiography Study

Purpose

To investigate macular microvasculature changes using optical coherence tomography angiography (OCTA) and analyze their correlation with the structural parameters in highly myopic eyes.

Methods

We measured the area of the foveal avascular zone (FAZ) and the parafoveal vessel density in the superficial and deep retinal plexuses using OCTA. The magnification effect of the FAZ area was corrected using Bennett's formula. Retinal thickness measured at each corresponding area of the OCTA parameters, subfoveal choroidal thickness, and ocular characteristics were reviewed, and the relationships between the microvasculature measurements and the ocular structural characteristics were explored.

Results

Fifty-two eyes with high myopia and 52 normal sex- and age-matched controls were included in the analysis. The FAZ area was significantly larger in the myopic eyes (p = 0.023). The superficial parafoveal vascular density was significantly decreased (p = 0.007) in the myopic eyes compared with the normal eyes, whereas there was no significant difference in the deep parafoveal vascular density (p = 0.226). Regarding the retinal thickness, only the parafoveal inner retinal thickness was significantly smaller in the myopic eyes than in the normal eyes (p = 0.023). The FAZ and subfoveal choroidal thickness were significantly correlated with the axial length, and the parafoveal inner retinal thickness was significantly correlated with the superficial parafoveal vascular density (all p < 0.05).

Conclusions

The FAZ was enlarged and the parafoveal vascular density was reduced in the highly myopic eyes. The decrease was prominent in the superficial capillary plexuses and well-correlated with the retinal thickness profiles. The macular microvascular network alteration may be attributed to the ocular axial elongation that occurs with myopia.

Evaluation of retinal and choroidal changes in patients with Alzheimer's type dementia using optical coherence tomography angiography

AIM

To evaluate the changes in fundus parameters in patients with Alzheimer's type dementia (ATD) using optical coherence tomography angiography (OCTA), to record flash electroretinograms (ERG) using the RETeval system and to explore changes in retinal function.

METHODS

Twenty-nine patients with ATD and 26 age-matched normal subjects were enrolled. All subjects underwent OCTA scans to analyse the superficial retinal vessel parameters in the macular area, including the vessel length density, the vessel perfusion density and the area of foveal avascular zone (FAZ), as well as the choroidal thickness. The differences between the patients with ATD and the normal control group were compared and explored the relevant factors affecting vessel parameters. We also recorded the flash ERGs using the RETeval system and intended to explore changes in retinal function by analysing the ERG image amplitude in patients with ATD.

RESULTS

The vessel parameters [P _{vessel length density}=0.005 and P _{vessel perfusion density}=0.006) and average choroid thickness (P<0.001) in the macular area of the ATD group was less than the control group. The FAZ area was statistically significantly enlarged in the ATD group (P<0.001). These parameters were correlated with the Mini-Mental State Examination (MMSE) score and the Montreal Cognitive Assessment (MoCA).

CONCLUSION

Patients with ATD exhibit decreases in the parameters associated with fundus. In addition, these indicators significantly correlate with the MMSE score and the MoCA score. OCTA may be an adjunct tool with strong potential to track changes in the diagnosis and monitoring the progression of the disease.

Retinal microvascular density modifications during the water drinking test

PURPOSE

The water drinking test (WDT) is a well-known stress test that increases intraocular pressure (IOP) momentarily and can indicate risk of glaucoma progression. This study focuses on correlating changes in the retinal microvascular plexus with the WDT in young healthy subjects.

METHODS

A total of 20 eyes of 20 healthy young subjects (mean age 24.37 ± 2.17 years) were included in this study. In our protocol, WDT consisted of drinking 1 L of water within 5 min. Outcome measures in this prospective observational study were mean arterial pressure (MAP), heart rate (HR), IOP, and retinal vessel density of both superficial and deep macular retina using optical coherence tomography angiography (OCTA), which were assessed before water ingestion and four times after at 15-min intervals. OCTA images were later quantified by fractal analysis (box counting [D_box]). One-way repeated measures analysis of variance (ANOVA) was used to assess the effects of WDT on each of the parameters.

RESULTS

The WDT resulted in significant peak changes of the following parameters compared to baseline: IOP: 15.63 ± 3.37 versus 18.38 ± 4.53 mmHg at 30 min, p < 0.001; HR: 75.74 ± 12.23 versus 64.95 ± 11.37 bpm at 15 min, p < 0.001; deep retinal vessel density 1.758 ± 0.14 versus 1.749 ± 0.16 at 15 min, p = 0.040.

CONCLUSIONS

Besides IOP elevation and systemic effects in HR, WDT is associated with temporary modifications of the deep vascular plexus in young healthy subjects.

Macular Vessel Density Changes in Young Adults With High Myopia: A Longitudinal Study

Background: To characterize the longitudinal changes of macular vessel density in young adults and its associated factors.

Methods: The right eyes of 309 participants (75 high myopic, 194 mild-to-moderate myopic, and 40 healthy) were followed up for 21 months. OCTA images were acquired at two visits using follow-up scans. Macular vessel density was calculated globally and in the nine early treatment diabetic retinopathy study (ETDRS) subfields of the macula superficial layer.

Results: The macular vessel density significantly decreased in young myopes after a 21-month follow up (p < 0.05), with variations among sectors. Compared with healthy eyes, HM group exhibited a faster reduction in global macular vessel density (p = 0.0307) as well as in sectors of inner-inferior (II), inner-temporal (IT), and outer-temporal (OT) (all p < 0.05). Multivariate regression analysis showed that longer baseline axial length (AL) was significantly associated with larger reduction of macular vessel density in the inner-inferior, inner-temporal and outer-temporal sectors (all p < 0.05).

Conclusions: Compared with emmetropes, high myopes presented greater loss of macular vessel density over time in global and in the inner-inferior, inner-temporal and outer-temporal sectors. A longer baseline AL was associated with larger changes of macular vessel density in the inner-inferior, inner-temporal and outer-temporal sectors.

A method for the automatic detection of myopia in Optos fundus images based on deep learning

Myopia detection is significant for preventing irreversible visual impairment and diagnosing myopic retinopathy. To improve the detection efficiency and accuracy, a Myopia Detection Network (MDNet) that combines the advantages of dense connection and Residual Squeeze-and-Excitation attention is proposed in this paper to automatically detect myopia in Optos fundus images. First, an automatic optic disc recognition method is applied to extract the Regions of Interest and remove the noise disturbances; then, data augmentation techniques are implemented to enlarge the data set and prevent overfitting; moreover, an MDNet composed of Attention Dense blocks is constructed to detect myopia in Optos fundus images. The results show that the Mean Absolute Error of the Spherical Equivalent detected by this network can reach 1.1150 D (diopter), which verifies the feasibility and applicability of this method for the automatic detection of myopia in Optos fundus images.

Assessment of the Macular Microvasculature in High Myopes With Swept Source Optical Coherence Tomographic Angiography

Background: The risk of pathologic myopia (PM) increases with worsening myopia and may be related to retinal microvasculature alterations. To evaluate this, we analyzed the macular microvasculature of myopes with swept source-optical coherence tomographic angiography (SS-OCTA) in adolescent and young adult Singaporeans.

Methods: This is a prevalent case-control study including 93 young Chinese from the Strabismus, Amblyopia and Refractive error in Singaporean children (STARS, N = 45) study and the Singapore Cohort Study of Risk Factors for Myopia (SCORM, N = 48) studies. Macular vessel density (VD) measurements were obtained from 3 × 3 mm SS-OCTA scans and independently assessed using ImageJ. These measurements were compared between individuals with non-high myopia [non-HM, N = 40; SE >-5.0 diopter (D)] and HM (SE ≤-5.0D, N = 53).

Results: The mean macular VD was 40.9 ± 0.6% and 38.2 ± 0.5% in the non-HM and HM, groups, respectively (p = 0.01 adjusted for age and gender). Mean FAZ area in the superficial layer was 0.22 ± 0.02 mm² in the HM group, which was smaller compared to non-HM group (0.32 ± 0.03 mm², p = 0.04). Mean deep FAZ area was similar between the two groups (0.45 ± 0.03 mm² and 0.48 ± 0.04 mm² in the HM and non-HM groups, respectively, p = 0.70).

Conclusions: VD was lower and superficial FAZ area was smaller, in adolescents and young adults with HM compared to non-HM. These findings require validation in prospective studies to assess their impact on the subsequent development of PM.

Retinal microvasculature and optic disc alterations in non-pathological high myopia with optical coherence tomography angiography

PURPOSE

This study aims to investigate the early characteristics of retinochoroidal and peripapillary perfusion in non-pathological high myopia (HM) without retinopathy and compare them to the age- and sex-matched healthy subjects using optical coherence tomography angiography (OCTA).

METHODS

This prospective, cross-sectional study included 35 eyes of 35 patients in the non-pathological HM group (axial length (AL) ≥ 26 mm) and 35 eyes of 35 subjects in the control group. OCT and OCTA were used for the assessment of vessel density, foveal avascular zone, subfoveal choroidal thickness, choriocapillaris flow area, retinal nerve fiber layer thickness, and optic nerve head measurements.

RESULTS

The VDs of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were significantly reduced in the HM group (47.9 ± 3.8%; 47.3 ± 6.6%) compared to the control group (50.8 ± 2.6%; 54.1 ± 4.8%) (p < 0.001). The whole vessel density (wpVD) (53.7 ± 2.7% vs. 56.2 ± 2.2%) and peripapillary VD (ppVD) (56.4% (range, 45.8-60.4%) vs. 58.4% (range, 52.6-62.3%)) values were significantly lower in the HM group (p < 0.005). The inside disc vessel density (iVD) was similar in both groups (62 ± 3.3% vs. 61.4 ± 2.7%) (p = 0.511).

CONCLUSION

The vessel densities (VDs) of SCP and DCP, wpVD, and ppVD were lower in the non-pathological HM group, but the iVD value was similar in both groups. This suggests that the main cause of VD reduction is more likely related to globe elongation rather than reduced oxygen and nutrients due to the thinning of the posterior pole (retina, sclera, and choroid). CLINICALTRIALS.

GOV REGISTRATION ID

NCT04631991, 11/11/2020.

Repeatability of Macular and Optic Nerve Head Measurements by Optical Coherence Tomography Angiography in Healthy Children

Aims: To evaluate the repeatability of the peripapillary and macular vascular parameters using optical coherence tomography angiography (OCT-A) in healthy children.Materials and methods: Cross-sectional study including 34 eyes of 34 healthy children. After a complete medical examination, two consecutive OCT-A exams were done using AngioPlex Cirrus 5000 (Carl Zeiss Meditec, Dublin, CA, USA) in the same session. The scan area used was 6 × 6 mm for the analysis of the superficial vascular plexus (SVP) in the macula, and 4.5 × 4.5 mm for the peripapillary plexus. To study the repeatability of the measurements, the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) of each pair of exams were calculated.Results: The mean age of the children included was 10.77 ± 2.49 years (range 6 to 15 years). Good and excellent ICCs were obtained for all the parameters considered. Peripapillary vascular parameters showed greater reproducibility than macular ones (global peripapillary perfusion density (pPD): ICC = 0.834 CV = 0.89% vs. whole macular area PD (w-mPD): ICC = 0.697 CV = 3.49%; global peripapillary flux index (FI): ICC = 0.858 CV = 1.28%; whole macular area vascular density (VD): ICC = 0.699 CV = 3.30%). Amongst the macular parameters, the characteristics of the foveal avascular zone (FAZ) were the ones showing higher rates of repeatability (FAZ circularity: ICC = 0.858 CV = 8.83%).Conclusion: OCT-A is a non-invasive, time-efficient technology that may be useful in the evaluation of the retinal and peripapillary vascular network in healthy children. The repeatability of the measures will allow the follow-up and evaluation of any change occurring in the macular or optic nerve perfusion.

Advances in translational imaging of the microcirculation

The past few decades have seen an explosion in the development and use of methods for imaging the human microcirculation during health and disease. The confluence of innovative imaging technologies, affordable computing power, and economies of scale have ushered in a new era of "translational" imaging that permit us to peer into blood vessels of various organs in the human body. These imaging techniques include near-infrared spectroscopy (NIRS), positron emission tomography (PET), and magnetic resonance imaging (MRI) that are sensitive to microvascular-derived signals, as well as computed tomography (CT), optical imaging, and ultrasound (US) imaging that are capable of directly acquiring images at, or close to microvascular spatial resolution. Collectively, these imaging modalities enable us to characterize the morphological and functional changes in a tissue's microcirculation that are known to accompany the initiation and progression of numerous pathologies. Although there have been significant advances for imaging the microcirculation in preclinical models, this review focuses on developments in the assessment of the microcirculation in patients with optical imaging, NIRS, PET, US, MRI, and CT, to name a few. The goal of this review is to serve as a springboard for exploring the burgeoning role of translational imaging technologies for interrogating the structural and functional status of the microcirculation in humans, and highlight the breadth of current clinical applications. Making the human microcirculation "visible" in vivo to clinicians and researchers alike will facilitate bench-to-bedside discoveries and enhance the diagnosis and management of disease.

The Role of Multimodal Approach in the Assessment of Glaucomatous Damage in High Myopes

Purpose

To compare the optic disc structure and peripapillary retinal function between high myopes with and without glaucoma and to address the differential role of papillary optical coherence tomography angiography (OCT-A) and circumpapillary microperimetry (cpMP) on the diagnosis and prognosis of this patients.

Patients and Methods

It is a cross-sectional study including 30 high myopic patients (60 eyes), divided into 15 with (GG) and 15 without glaucoma (NGG). Demographic and clinical data were collected from patient records. Papillary structure (peripapillary retinal nerve fiber layer thickness, ppRNFLTs) and vascularization (small vessel densities, SVD´s) were assessed with SD-OCT (RTVue XR Avanti, with AngioVue system, Optovue^®). cpMP was carried out with the MP-3 microperimeter (Nidek^®).

Results

The GG were older, had lower best-corrected visual acuities and higher intraocular pressures and axial lengths (p<0.001). The GG showed lower values in all ppRNFLTs (p<0.05), lower values in all SVDs (p<0.001), except the SVD-inside disc (p=0.638) and lower retinal sensitivities within all cpMPs (p<0.001). The adjusted analysis computing the best two parameters per exam revealed that the anatomical model including the ppRNFLT-inferior and ppRNFLT-temporal and the vascular model including SVD-inferior and SVD-superior had the best discrimination power between groups, with cross-validated AUROCs of 0.9599 and 0.9921, respectively.

Conclusion

Despite the apparent superiority of the papillary vascular study, a multimodal approach including the papillary anatomic and circumpapillary microperimetric assessments can be the new way on the diagnosis and prognosis of glaucoma in high myopia.

Impact of cardiometabolic factors on retinal vasculature: A 3 × 3, 6 × 6 and 8 × 8-mm ocular coherence tomography angiography study

BACKGROUND

Ocular coherence tomography angiography (OCTA) is available in varying size and resolution. We sought to characterise associations of cardiometabolic factors with retinal microvascular changes using 3 × 3, 6 × 6 and 8 × 8-mm OCTA scans to determine differences in detection with varying scan size.

METHODS

Cross-sectional study of 247 cardiovascular patients from a single-centre tertiary-care hospital. Demographic, comorbidity and medication data were obtained. Patients underwent 3 × 3, 6 × 6 and 8 × 8-mm macula OCTA scanning using Carl Zeiss CIRRUS HD-OCT Model 5000. Angioplex and AngioTool software was used to quantify vascular parameters in the superficial capillary plexus.

RESULTS

Increasing age, hypertension, dyslipidaemia, diabetes, chronic kidney disease, coronary artery disease and peripheral vascular disease were associated with reductions in vessel density, vessel perfusion, average vessel length and/or junction density in 3 × 3-mm OCTA (P < .05 for all). Conversely, smoking was associated with increased vessel density, vessel length and junction density in 3 × 3-mm OCTA (P < .05 for all). Associations of vessel abnormalities with cardiometabolic factors were progressively weakened and statistically attenuated in 6 × 6 and 8 × 8-mm OCTA scans. In multivariate analyses, dyslipidaemia remained an independent predictor of reduced vessel density, average vessel length and junction density (P < .05).

CONCLUSIONS

Cardiometabolic factors are associated with multiple retinal microvascular changes in 3 × 3-mm OCTA scans. These associations were weakened and progressively attenuated in OCTA scans of larger 6 × 6 and 8 × 8-mm size. These findings advance our understanding of microcirculatory dysfunction and may have future implications for the screening and management of patients with cardiometabolic risk factors. Additional studies are required to further investigate these important associations.

Correlation between optic disc deformation and retinal vasculature in non-pathological high myopia

The aim of the current study was to investigate the correlation between optic disc deformation and retinal vasculature in high myopia. A total of 130 eyes with non-pathological high myopia were included in the current cross-sectional study. β-zone parapapillary atrophy (β-PPA), optic disc tilt ratio, and horizontal and vertical disc diameters were analyzed using fundus color photography. A 3x3 mm grid and a 4.5x4.5 mm grid were used to scan parafoveal and peripapillary regions, respectively, using optical coherence tomography angiography. Vessel flow density (VFD) and fractal dimension of the retina, as well as the foveal avascular zone (FAZ), were analyzed and quantified using en face projection images. Optic disc parameters that were associated with vascular changes were determined using multiple linear regression analysis. The results from the multivariate analysis revealed that β-PPA was negatively correlated with the VFD of the superficial retinal plexus (R=-2.805; P=0.006), deep retinal plexus (R=-2.801; P=0.006), radial parapapillary capillaries (R=-3.936; P<0.001) and enhanced-depth imaging of the fovea (R=-2.161; P=0.034). Additionally, FAZ was not significantly correlated with any factors in the current study. Age was negatively correlated with the VFD of the retina (R=-4.234; P<0.001), while the optic tilt ratio (R=-2.291; P=0.025) was negatively correlated with three sectors in the deep layer. Overall, the present results demonstrated that optic disc deformation was negatively correlated with the retinal microvasculature in non-pathological high myopia, particularly in the radial peripapillary capillaries and the deep retinal plexus. Therefore, optic disc deformation may be used to predict the retinal vasculature in high myopia.

Transient effect of suction on the retinal neurovasculature in myopic patients after small-incision lenticule extraction

PURPOSE

To characterize retinal neurovasculature changes after small-incision lenticule extraction (SMILE) in myopic patients.

SETTING

Ophthalmic Center, the Second Affiliated Hospital of Guangzhou Medical University, China.

DESIGN

Prospective interventional study.

METHODS

The corrected distance visual acuity/uncorrected distance visual acuity, corrected intraocular pressure (CIOP), and corneal tomography were evaluated at baseline (PRE), postoperative day (POD) 1, and POD 7. Ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thicknesses were measured. The vessel area densities (VADs, %), vessel skeleton densities (VSDs, %), vessel diameter index (VDI), and fractal dimensions (Dbox) of the superficial vascular plexus (SVP) and deep vascular plexus (DVP) were measured in a circular area (ϕ 2.5 mm) centered on the fovea.

RESULTS

A total of 38 myopic patients were recruited. The GCIPL thickness was increased after SMILE at POD 1 and POD 7 (P < .01) but no significant changes in the pRNFL thickness. The VAD, VSD, and Dbox of the SVP were decreased at POD 1 (P < .01), but not at POD 7. The VDI in small vessels of the SVP and DVP was decreased at POD 1 (P < .05) and increased at POD 7 (P < .05). Changes in CIOP were positively correlated with changes in the GCIPL thickness. Changes in CIOP were negatively correlated with changes in the VAD of small vessels and the Dbox of total vessels in the DVP. Changes in CIOP were negatively correlated with the VSD and VDI of small vessels in the DVP and changes in the VDI of big vessels in the SVP.

CONCLUSIONS

The transient fluctuations in the retinal neurovasculature after SMILE may represent a characteristic homeostasis pattern in patients after refractive surgery.

Retinal applications of swept source optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA)

The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited. In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.

Quantitative OCT angiography of the retinal microvasculature and choriocapillaris in highly myopic eyes with myopic macular degeneration

PURPOSE

To quantify retinal and choriocapillaris (CC) microvasculature in highly myopic (HM) eyes with myopic macular degeneration (MMD) using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

162 HM eyes (spherical equivalent ≤ -6.0 dioptres or axial length (AL) ≥26.5 mm) from 98 participants were enrolled, including 60 eyes (37.0%) with tessellated fundus, 54 eyes (33.3%) with peripapillary diffuse chorioretinal atrophy (PDCA), 27 eyes (16.7%) with macular diffuse chorioretinal atrophy (MDCA) and 21 eyes (13.0%) with patchy or macular atrophy. PLEX Elite 9000 SS-OCTA was performed to obtain perfusion densities (PD) of the superficial and deep retinal capillary plexus, and CC signal voids (number, area and density).

RESULTS

Retinal PD decreased with increasing severity of MMD. Multivariable analysis showed that after adjustment of age and other factors, retinal PD decreased significantly in eyes with longer AL (β≤-0.51, p<0.001) and with an MMD severity of MDCA or worse (β≤-1.63, p<0.001). Reduced retinal PD were significantly associated with worse vision (β≤-0.01, p≤0.04). In terms of CC signal voids, multivariable analysis showed that longer AL (p<0.001), but not MMD severity (p≥0.12) was significantly associated with CC signal void changes in the earliest stage of MMD.

CONCLUSION

We demonstrate significant OCTA alterations in the retina and CC in HM eyes with varying severities of MMD. In eyes with early-stage PDCA, lower retinal PD and more extensive CC signal voids are predominantly associated with increasing AL. In contrast, in eyes with MDCA or worse, MMD itself was associated with sparser retinal and CC circulation.

Choroidal blood perfusion as a potential "rapid predictive index" for myopia development and progression

Myopia is the leading cause of visual impairment worldwide. The lack of a "rapid predictive index" for myopia development and progression hinders the clinic management and prevention of myopia. This article reviews the studies describing changes that occur in the choroid during myopia development and proposes that it is possible to detect myopia development at an earlier stage than is currently possible in a clinical setting using choroidal blood perfusion as a "rapid predictive index" of myopia.

Compensatory Changes in the Anterior Segment and Vascular System of the Eye in Myopic Children After Orthokeratology

Purpose: To analyze changes in the anterior segment, retinal vessel density, and choroidal thickness (ChT) after orthokeratology (Ortho-K). Methods: Myopic children were enrolled from Ruijin Hospital, Shanghai, China. Ortho-K lenses and single-vision spectacles were fitted for myopia correction. Ocular measurements were taken at baseline and 6 months, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), ChT, macular vessel density (MVD), and optic disc vessel density (OVD). Results: Seventy-six patients were enrolled in this study, including 40 in the Ortho-K group and 36 in the control group. At baseline, no parameters between the two groups were statistically different. After 6 months, changes in CCT and ACD decreased in the Ortho-K group compared with those in the control group (p < 0.05); LT and ChT in the Ortho-K group were thicker than those in the control group (p < 0.05), while there was no difference in MVD and OVD compared with those in the control group (p > 0.05). There were moderate positive correlations between ChT and LT and between ChT and OVD in the Ortho-K group (p < 0.05). Conclusion: The changes in the anterior and posterior segments of the eye after Ortho-K lens wearing suggest that the human eye has a powerful compensatory effect on the imposed defocus.

Cilioretinal Arteries in Highly Myopic Eyes: A Photographic Classification System and Its Association With Myopic Macular Degeneration

Purpose: To develop a photographic classification for cilioretinal arteries and to investigate its association with myopic macular degeneration (MMD).

Methods: One thousand six hundred ninety-two highly myopic eyes of 1,692 patients were included. The presence of a cilioretinal artery was determined by fundus photographs, and a photographic classification was proposed. MMD was classified according to the International META-PM Classification. Associations of the cilioretinal artery and its classifications with MMD and visual acuity were analyzed.

Results: Of the eyes tested, 245 (14.5%) had a cilioretinal artery. The cilioretinal arteries were classified into four categories (temporal “cake-fork,” 35.92%; temporal “ribbon,” 53.47%; “multiple,” 6.53%; “nasal,” 4.08%) and 3 distributions based on whether its visible branches reached the central foveal area. Eyes with cilioretinal arteries had significantly less MMD of grade ≥3 and better visual acuity than those without (P < 0.01). Multiple linear regression analysis showed that younger age, male sex, shorter axial length, and the presence of a cilioretinal artery were associated with better visual acuity in highly myopic eyes (all P < 0.05). The “nasal” category presented more MMD with grade ≥3 and worse visual acuity than the other categories (P < 0.05), whereas the “multiple” category contained no eyes with MMD grade ≥3. The cilioretinal arteries reaching the central foveal area showed less MMD of grade ≥3 and better visual acuity than those not (P < 0.05).

Conclusions: We propose a photographic classification for cilioretinal arteries that has good clinical relevance to visual functions. The cilioretinal artery may potentially afford protection against MMD.

Analysis of macular microvasculature and thickness after ICL implantation in patients with myopia using optical coherence tomography

AIM

To investigate changes in macular vessels and thickness in myopic eyes after intraocular collamer lens (ICL) implantation using quantitative optical coherence tomography angiography (OCTA).

METHODS

This retrospective included 73 myopic eyes of 73 patients (average age, 27.53±6.16y) who underwent ICL implantation (28 eyes were Toric ICL). Axial length (AL), uncorrected visual acuity (UCVA), refractive dioptre (RD), intraocular pressure (IOP) and OCTA were measured and compared with before and 1wk, 1, and 3mo after surgery. OCTA was used to image vessel density (VD) and skeleton density (SD) in both the superficial (SCP) and deep capillary plexus (DCP). Central retinal thickness (CRT) and ganglion cell-inner plexiform layer thickness (GCT) were also measured. Changes between pre- and postoperative measurements were analysed by repeated measures analysis of variance.

RESULTS

Compared with preoperative data, postoperative data on UCVA revealed significant improvements in all patients (P<0.05). However, there was no significant difference in IOP. After the operation, CRT and GCT exhibited significant changes (P<0.05). Among these measures, CRT was significantly higher at one and three months postoperative (all P<0.01). GCT was significantly higher at 1wk, 1, and 3mo postoperative (all P<0.01). Changes in VD and SD were nonsignificant in both the SCP and DCP. There was no difference in postoperative changes between the ICL and Toric ICL groups.

CONCLUSION

ICL and Toric ICL implantation both have good efficacy and safety for myopic eyes, but macular area changes that occur after surgery need attention.

Transient Alteration of Retinal Microvasculature after Refractive Surgery

PURPOSE

The purpose of this study was to determine the retinal microvasculature in myopic patients after refractive surgery.

METHODS

Thirty-six right eyes of 36 patients who undertook femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) were imaged using optical coherence tomography angiography preoperatively, 1-week, 1-month, and 3-month postoperation, respectively. Vessel density was analyzed after the correction of magnification, and results were correlated with clinical manifestations, including spherical equivalent (SE), amplitude of accommodation, intraocular pressure, and axial length.

RESULTS

There was a significant decrease in microvascular density 1-week postoperation compared to preoperative measurement (p < 0.05), and it recovered 1-month postoperation. Microvascular densities in superficial vascular plexus (r = 0.528, p < 0.01), deep vascular plexus (r = 0.500, p < 0.01), and retinal vascular network (r = 0.390, p < 0.05) were all positively correlated with the decrease of the SE 1-week postoperation.

CONCLUSION

The transient alteration of the retinal microvasculature after refractive surgery appeared to recover quickly, which may not impact the visual function after FS-LASIK.

Clinical efficacy of phacoemulsification combined intraocular lens implantation for treatment of high myopia with cataract: A protocol of systematic review

BACKGROUND

The purpose of this study is to assess the clinical efficacy of phacoemulsification combined intraocular lens implantation (PILI) for the treatment of high myopia with cataract (HMC).

METHODS

In this study, the electronic databases (PUBMED, EMBASE, Cochrane Library, Scopus, AMED, CINAHL, PsychINFO, CBM, and China National Knowledge Infrastructure) will be searched from inception to present. All randomized controlled trials on assessing the PILI for patients with HMC will be included. Two authors will carry out study selection, information extraction, and study quality assessment, respectively. We will invite another author to solve any disagreement through discussion. RevMan 5.3 software will be performed for data synthesis and analysis.

RESULTS

This study will present a detailed synthesis and/or descriptive analysis of the most recent evidence to evaluate the efficacy of PILI for HMC.

CONCLUSION

The results of this study may provide possible guidance to determine whether or not PILI is effective on HMC.

The Effect of Software Versions on the Measurement of Retinal Vascular Densities Using Optical Coherence Tomography Angiography

BACKGROUND

The goal of the study was to determine the effect of different software versions on the measurement of retinal vessel densities using optical coherence tomography angiography (OCTA) in normal subjects.

METHODS

Thirty-two eyes of eighteen healthy subjects were imaged using two OCTA devices: the Optovue RTVue and the Zeiss Cirrus. The macular 3 × 3 mm scan protocol was used. The images acquired using the Optovue OCTA device were exported using two different software versions in the system and compared to the images acquired through the Zeiss OCTA. In addition, the Optovue OCTA images were exported after manual adjustment of the segmentation boundaries according to the intraretinal layer definition. The densities of the superficial vascular plexus (SVP) and deep vascular plexus (DVP) were measured using fractal analysis by box-counting (Dbox).

RESULTS

Both the vessel densities of the SVP and DVP acquired using the Optovue OCTA device were significantly different when compared to those from the Zeiss OCTA device (all, P <.05). No significant difference was found between the vessel densities of the SVP exported using both the new and old versions of Optovue (P >.05). However, the DVP exported using the new Optovue software version was significantly different compared to those exported using the old version (P <.05). The vessel densities of the SVP and DVP were related among the Optovue OCTA software versions and manual adjustment method (r ranged from 0.55 to 0.77; all P <.05).

CONCLUSION

This is the first study to determine that different software versions with various intraretinal layer segmentation methods affect the vessel density measurements of the SVP and DVP.

Characterization of retinal microvasculature and its relations to cognitive function in older people after circuit resistance training

PURPOSE

To characterize the changes of retinal microvascular density and their relations to cognitive function in the healthy older people without known cognitive impairment after an 8-week high-speed circuit resistance training program (HSCT).

METHODS

Twenty cognitively normal older people were recruited and randomly assigned to either the HSCT group or control group (CON). Twelve subjects (age 70.8 ± 5.8 yrs) in the HSCT group trained three times per week for 8 weeks. Eight subjects in the CON group (age 71.8 ± 4.8 yrs) did not perform formal training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at 8-week follow-up. The densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. In addition, their cognitive functions were tested using the NIH toolbox.

RESULTS

There were significant increases in pattern comparison processing speed (PAT, P = 0.02) and fluid composite score (FCS, P = 0.005) at the follow-up in the HSCT group. Although the vessel densities did not differ between visits in either group, the variation (i.e., change) in retinal vessel density of SVP was negatively related to the changes of FCS (r = -0.54, P = 0.007) and the List Sorting Working Memory test (r = -0.43, P = 0.039) in the HSCT group.

CONCLUSIONS

This is the first study to reveal that the individual response of the SVD was related to the improvement in the cognition in cognitively normal older people after HSCT.

Myopia-related stepwise and quadrant retinal microvascular alteration and its correlation with axial length

PURPOSE

To investigate the characteristics of retinal vascular alterations in patients with varying degrees of myopia, and to determine correlated variables and alteration patterns over different retinal zones.

METHODS

A total of 208 right eyes of 208 patients with myopia were enrolled and divided into mild, moderate, high, and extreme myopia groups. The macular vasculature in superficial, deep, and whole retinal layers was imaged with optical coherence tomography angiography (OCTA). The vessel densities over the whole annular zone, four quadrants, and six annuli were quantified as fractal dimension using a customized software. Simple linear regressions and ridge regression were used to determine and compare explanatory variables of microvascular density.

RESULTS

The microvascular density within the superficial, deep and whole retinal layers was highest in mild myopia group, second highest in moderate myopia group, second lowest in high myopia group and lowest in extreme myopia group. Within the same layer, differences between any two groups were significant (all p < 0.05). Among the four quadrants, only the inferior nasal (IN) quadrant showed no difference in microvascular density between mild and moderate groups. Ridge regression indicated that microvascular density values in all three layers were more strongly correlated with axial length (AL) (scaled estimates -0.139, -0.103, -0.154; all p < 0.001) than with spherical equivalent (SE) (scaled estimates -0.052, -0.096, -0.057; all p < 0.05).

CONCLUSIONS

We characterized a stepwise and quadrant alteration of retinal microvascular density from mild to extreme myopia, which was more strongly affected by axial elongation, although both AL and SE were meaningful indicators.

Short-term changes in the anterior segment and retina after small incision lenticule extraction

Background

To analyse short-term changes in the anterior segment and retina after small incision lenticule extraction (SMILE).

Methods

Patients with myopia scheduled for SMILE were recruited from Ruijin Hospital, Shanghai, China. Basic patient information such as age, sex, and refractive errors was recorded. Ocular measurements were taken before surgery, and 1 day and 1 week after surgery; they included axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), pupil diameter (PD), macular thickness (MT), ganglion cell layer thickness (GCL), retinal nerve fiber layer thickness (RNFL), choroidal thickness (CT), macular vessel density, and optic disc vessel density.

Results

Sixty-one eyes of 31 patients were selected for this study. AL, CCT, ACD, and postoperative PD were significantly reduced (p < 0.05), while LT was thickened after surgery (p < 0.05). MT at the fovea decreased 1 day and 1 week after surgery (p < 0.05). GCL showed no significant changes after surgery. RNFL was unchanged 1 day after surgery, but the inferior sector was thickened 1 week after surgery. CT was thicker at the fovea 1 day after surgery and 1.0 mm from the fovea in the nasal sector 1 week after surgery. Macular vessel density was significantly decreased 1 day after surgery and most recovered in 1 week. Optic disc vessel density decreased at the peripapillary part 1 day after surgery and recovered after 1 week. ΔACD and ΔLT showed no significant correlation 1 day after surgery. ΔACD was negatively correlated with ΔLT and sphere 1 week after surgery (r = − 0.847, p < 0.000; r = − 0.398, p = 0.002). ΔLT was positively correlated with the sphere 1 week after surgery (r = 0.256, p = 0.048).

Conclusion

The anterior segment was the most affected, while the retina also underwent changes with regard to MT, RNFL, CT, macular vessel density, and peripapillary vessel density.

Vascular density with optical coherence tomography angiography and systemic biomarkers in low and high cardiovascular risk patients

We aimed to compare retinal vascular density in Optical Coherence Tomography Angiography (OCT-A) between patients hospitalized for acute coronary syndrome (ACS) and control patients and to investigate correlation with angiogenesis biomarkers. Patients hospitalized for an acute coronary syndrome (ACS) in the Intensive Care Unit were included in the "high cardiovascular risk" group while patients without cardiovascular risk presenting in the Ophthalmology department were included as "control". Both groups had blood sampling and OCT-A imaging. Retina microvascularization density in the superficial capillary plexus was measured on 3 × 3 mm angiograms centered on the macula. Angiopoietin-2, TGF-β1, osteoprotegerin, GDF-15 and ST-2 were explored with ELISA or multiplex method. Overall, 62 eyes of ACS patients and 42 eyes of controls were included. ACS patients had significantly lower inner vessel length density than control patients (p = 0.004). A ROC curve found that an inner vessel length density threshold below 20.05 mm^-1 was moderately associated with ACS. Significant correlation was found between serum levels of angiopoietin-2 and osteoprotegerin, and retinal microvascularization in OCT-A (R = - 0.293, p = 0.003; R = - 0.310, p = 0.001). Lower inner vessel length density measured with OCT-A was associated with ACS event and was also correlated with higher concentrations of angiopoietin-2 and osteoprotegerin.

Deep Retinal Capillary Plexus Decreasing Correlated With the Outer Retinal Layer Alteration and Visual Acuity Impairment in Pathological Myopia

Purpose

The purpose of this study was to measure alterations of inner retinal microvascular density and outer retinal sublayer thicknesses in pathological myopia, and to correlate the measured parameters with best corrected visual acuity (BCVA).

Methods

Optical coherence tomography (OCT) and OCT angiography (OCTA) images of 21 control, 48 simple high myopia, and 22 pathological myopia eyes were analyzed to quantify the thicknesses of the outer retinal sublayers and the density of the inner retinal microvascular network that includes the superficial retinal capillary plexus (SRCP) and deep retinal capillary plexus (DRCP). Retinal sublayer thicknesses and microvascular densities were compared among the three groups, and correlations of sublayer thicknesses and microvascular densities with BCVA were determined.

Results

In pathological myopia, density of the DRCP, thicknesses of myoid and ellipsoid zone (MEZ), interdigitation zone and retinal pigment epithelium/Bruch complex (IZ + RPE), and choroid were lower than in simple high myopia (P < 0.05). The decreased DRCP density was correlated with thinner MEZ and IZ+RPE in pathological myopia (P < 0.05), but not in simple high myopia (P > 0.05). Simple linear regression showed that axial length, female, thicknesses of outer plexiform layer (OPL), MEZ, IZ + RPE, choroid, and density of the SRCP and DRCP were correlated with BCVA. In multiple regression analysis, worse BCVA was associated only with thinner MEZ, thinner choroid, and decreased DRCP (P < 0.05).

Conclusions

Alteration of inner retinal microvascular density and outer retinal sublayer thicknesses occurred in pathological myopia, especially decreased DRCP and thinner MEZ, which were significantly associated with worse BCVA.

Refractive Errors, Ocular Biometry and Diabetic Retinopathy: A Comprehensive Review

Purpose: To summarize the association between diabetic retinopathy and refractory status as well as ocular biometric parameters; To review the theories of the protective effect of high myopia against diabetic retinopathy. Methods: A comprehensive literature search on MEDLINE, EMBASE, Web of Science and Scopus databases as well as reference list search, and systematic review of relevant publications.  Results: Myopia may delay the onset and progression of diabetic retinopathy. Increased axial length in myopia is associated with reduced risk of any diabetic retinopathy and vision-threatening diabetic retinopathy. The possible mechanisms for the protective effect of myopia against diabetic retinopathy may include posterior vitreous detachment, change in retinal blood flow and oxygen demand, choroidal thinning and altered cytokine profiles.  Conclusions: High myopia may be a protective factor against the onset and progression of diabetic retinopathy. Further studies about the mechanisms of how myopia, axial length and ocular biometrics influence the onset and progression of DR are needed.

Effect of color information on the diagnostic performance of glaucoma in deep learning using few fundus images

PURPOSE

The purpose of this study was to evaluate the accuracy of the convolutional neural network (CNN) model in glaucoma identification with three primary colors (red, green, blue; RGB) and split color channels using fundus photographs with a small sample size.

METHODS

The dataset was prepared using color fundus photographs captured with a fundus camera (VX-10i, Kowa Co., Ltd., Tokyo, Japan). The training dataset consisted of 200 images, and the validation dataset contained 60 images. In the preprocessing stage, the color channels for the fundus images were separated into red (red model), green (green model), and blue (blue model) using OpenCV on Windows. All images were resized to squares with a size of 512 × 512 pixels for preprocessing before input into the model, and the model was fine-tuned with VGG16.

RESULTS

The diagnostic performance was significantly higher in the green model [area under the curve (AUC) 0.946; 95% confidence interval (CI) 0.851-0.982] than in the RGB model (AUC 0.800; 95% CI 0.658-0.893; P = 0.006), red model (AUC 0.746; 95% CI 0.601-0.851; P = 0.002), and blue model (AUC 0.558; 95% CI 0.405-0.700; P < 0.001).

CONCLUSION

The present study showed that the green digital filter is useful for structuring CNN models for automatic discrimination of glaucoma using fundus photographs with a small sample size. The present findings suggest that preprocessing, when creating the CNN model, is an important step for the identification of a large number of retinal diseases using color fundus photographs.

Cilioretinal Arteries and Macular Vasculature in Highly Myopic Eyes: An OCT Angiography-Based Study

PURPOSE

To determine the association between the presence of cilioretinal arteries and the macular vasculature in highly myopic eyes using OCT angiography (OCTA).

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Four hundred eighty-one highly myopic eyes of 481 patients.

METHODS

Fundus photographs were reviewed to determine the presence of a cilioretinal artery and its distribution, based on whether its path or visible branches reached the region within 500 μm of the foveal center. The macular vasculature was analyzed in OCTA images, including the vessel density (VD), fractal dimension (FD), and foveal avascular zone (FAZ). The associations between the presence of a cilioretinal artery and its distribution and between the macular vasculature and visual acuity were evaluated.

MAIN OUTCOME MEASURES

Cilioretinal arteries, macular vasculature, and their associations.

RESULTS

Of the eyes included, 17.05% (82/481) had a cilioretinal artery. Based on the OCTA analysis, the eyes with cilioretinal arteries showed significantly higher VD and FD in both superficial and deep capillary plexuses and smaller FAZ than those without (all P < 0.001). However, these differences were not found in the subgroup of eyes with an axial length of more than 30 mm. Eyes with cilioretinal arteries that reached the central foveal area showed significantly higher VD and FD in both capillary plexuses and smaller FAZ than those that did not (all P < 0.05). Better best-corrected visual acuity was identified in the eyes with cilioretinal arteries than in those without (0.09 ± 0.14 logarithm of the minimum angle of resolution [logMAR] vs. 0.21 ± 0.27 logMAR, respectively; P < 0.001). In particular, eyes with cilioretinal arteries that reached the central foveal area had better visual acuity than those without (0.05 ± 0.06 logMAR vs. 0.16 ± 0.20logMAR, respectively; P = 0.005).

CONCLUSIONS

This OCTA-based study suggested that cilioretinal arteries in highly myopic eyes potentially may improve the macular vasculature and influence visual function.

Altered Macular Microvasculature in Mild Cognitive Impairment and Alzheimer Disease

BACKGROUND

The goal of the present study was to analyze the macular microvacular network in mild cognitive impirment (MCI) and Alzheimer disease (AD).

METHODS

Twelve patients with AD and 19 patients with MCI were recruited together with 21 cognitively normal controls with a similar range of ages. Optical coherence tomography angiography was used to image the retinal microvascular network at the macular region, including retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP). Fractal analysis (box counting, Dbox) representing the microvascular density was performed in different annular zones and quadrantal sectors. The macular ganglion cell-inner plexiform layer (GC-IPL) thickness was measured using Zeiss OCT. The relationship between the retinal microvasculature and clinical manifestations was analyzed.

RESULTS

Patients with AD had lower densities of RVN, SVP, and DVP in the annulus, from 0.6 to 2.5 mm in diameter (P < 0.05) in comparison with controls. Patients with MCI had lower density of DVP in the superior nasal quadrant (P < 0.05) than that of the controls. There were no significant differences of GC-IPL thickness among groups (P > 0.05). There was a trend of vascular density loss from control to MCI then AD (P < 0.05). Retinal microvascular density of DVP was correlated with GC-IPL thickness (P < 0.05) in patients with AD, but not in patients with MCI and controls.

CONCLUSIONS

Patients with AD had less density of retinal microvascular networks than controls. Our findings suggest the presence of retinal microvascular dysfunction in AD.