Macular and peripapillary vessel density in myopic eyes of young Chinese adults

Morphological characteristics of the foveal avascular zone in pathological myopia and its relationship with macular structure and microcirculation

PURPOSE

To explore the characteristics of macular structure, microcirculation, and foveal avascular zone (FAZ) morphology in pathological myopia and to research the associations between these factors and pathological myopia.

METHODS

This is a cross-sectional study. The study included 103 eyes with non-high myopia and 206 eyes with high myopia (139 with simple high myopia and 67 with pathological myopia). Macular structural and microcirculation parameters were determined using optical coherence tomography angiography (OCTA). The FAZ morphological parameters were measured manually using Image J software. Correlations between pathological myopia and various factors were analyzed.

RESULTS

Patients with pathological myopia had a thinner retinal thickness (RT) and choroidal thickness (CT) and a lower retinal superficial vascular density (SVD), retinal deep vascular complex density (DVD), choriocapillaris perfusion area (CCPA), and choroidal vascularity index (CVI) (all P < 0.05). Patients with pathological myopia had a larger FAZ area, perimeter, major axis, minor axis, acircularity index (AI), and lower circularity index (CI) (all P < 0.01). The axial length (AL), the major axis of the superficial FAZ, CI, and AI were significantly correlated with myopia severity (all P < 0.05).

CONCLUSIONS

Patients with pathological myopia exhibited worse macular microcirculation and thinner macular retina and choroid. The FAZ in pathological myopia was larger and more irregular. The AL, CI, and AI were significantly associated with myopia severity. Thus, CI and AI might serve as new indicators for monitoring the progression of myopia. Further investigations should be performed.

TRIAL REGISTRATION

Clinical Trials.gov Identifier: ChiCTR2100046590.

Macula structural and vascular differences in glaucoma eyes with and without high axial myopia

AIMS

To identify clinically relevant parameters for identifying glaucoma in highly myopic eyes, an investigation was conducted of the relationship between the thickness of various retinal layers and the superficial vessel density (sVD) of the macula with axial length (AL) and visual field mean deviation (VFMD).

METHODS

270 glaucoma patients (438 eyes) participating in the Diagnostic Innovations in Glaucoma cross-sectional study representing three axial myopia groups (non-myopia: n=163 eyes; mild myopia: n=218 eyes; high myopia (AL>26 mm): n=57 eyes) who completed macular optical coherence tomography (OCT) and OCT-angiography imaging were included. Associations of AL and VFMD with the thickness of the ganglion cell inner plexiform layer (GCIPL), macular retinal nerve fibre layer (mRNFL), ganglion cell complex (GCC), macular choroidal thickness (mCT) and sVD were evaluated.

RESULTS

Thinner Global GCIPL and GCC were significantly associated with worse VFMD (R2=34.5% and R2=32.9%; respectively p<0.001), but not with AL (all p>0.1). Thicker mRNFL showed a weak association with increasing AL (R2=2.4%; p=0.005) and a positive association with VFMD (global R2=19.2%; p<0.001). Lower sVD was weakly associated with increasing AL (R2=1.8%; p=0.028) and more strongly associated with more severe glaucoma VFMD (R2=29.6%; p<0.001). Thinner mCT was associated with increasing AL (R2=15.5% p<0.001) and not associated with VFMD (p=0.194). mRNFL was thickest while mCT was thinnest in all sectors of high myopic eyes.

CONCLUSIONS

As thinner GCIPL and GCC were associated with increasing severity of glaucoma but were not significantly associated with AL, they may be useful for monitoring glaucoma in highly myopic eyes.

Characteristics of the optic disc in young people with high myopia

PURPOSE

This study aimed to investigate the characteristics of the optic disc in adolescents and young adults with high myopia by applying optical coherence tomography angiography.

METHODS

A total of 112 patients with high myopia (spherical equivalent refraction (SER) ≤ -6.00 D) aged 12 to 30 years old were enrolled in this cross-sectional study. Parapapillary atrophy (PPA) and ovality index from scanning laser ophthalmoscopy images and the degree of optic disc tilt from the optic nerve head (ONH) OCT B-scans were analysed using ImageJ and MATLAB software. Peripapillary retinal nerve fibre layer thickness (pRNFLT) and radial peripapillary capillary vessel density (RPC VD) around the optic disc were obtained from the images of the optic disc angiography scan.

RESULTS

In young high myopia patients, the PPA area was positively correlated with age, axial length (AL) and pRNFLT (all p < 0.05) and negatively correlated with SER (r = -0.222, p = 0.020). The degree of the optic disc tilt was associated with increasing AL and pRNFLT (all p < 0.05). The disc area was positively correlated with AL, pRNFLT, and RPC VD (all p < 0.05). In the multivariate regression analysis, PPA area was independently associated with the degree of optic disc tilt and disc area. The degree of optic disc tilt was affected by AL and PPA area while the change of disc area was influenced by PPA area and pRNFLT (all p < 0.05).

CONCLUSION

In young patients with high myopia, PPA area, the degree of optic disc tilt and disc area increased with AL and pRNFLT, while decreased with SER. The association between these factors was slightly different in the adolescent and young adult groups. The degree of the optic disc tilt was more associated with AL and SER in the adolescent group while disc area showed more correlated with AL and SER in the young adult group.

Functions of retinal astrocytes and Müller cells in mammalian myopia

Background

Changes in the retina and choroid blood vessels are regularly observed in myopia. However, if the retinal glial cells, which directly contact blood vessels, play a role in mammalian myopia is unknown. We aimed to explore the potential role and mechanism of retinal glial cells in form deprived myopia.

Methods

We adapted the mice form-deprivation myopia model by covering the right eye and left the left eye open for control, measured the ocular structure with anterior segment optical coherence tomography, evaluated changes in the morphology and distribution of retinal glial cells by fluorescence staining and western blotting; we also searched the online GEO databases to obtain relative gene lists and confirmed them in the form-deprivation myopia mouse retina at mRNA and protein level.

Results

Compared with the open eye, the ocular axial length (3.54 ± 0.006 mm v.s. 3.48 ± 0.004 mm, p = 0.027) and vitreous chamber depth (3.07 ± 0.005 mm v.s. 2.98 ± 0.006 mm, p = 0.007) in the covered eye became longer. Both glial fibrillary acidic protein and excitatory amino acid transporters 4 elevated. There were 12 common pathways in human myopia and anoxic astrocytes. The key proteins were also highly relevant to atropine target proteins. In mice, two common pathways were found in myopia and anoxic Müller cells. Seven main genes and four key proteins were significantly changed in the mice form-deprivation myopia retinas.

Conclusion

Retinal astrocytes and Müller cells were activated in myopia. They may response to stimuli and secretory acting factors, and might be a valid target for atropine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02643-0.

Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters.

Methods

OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis.

Results

A total of 1346 eyes from 792 participants were divided into 4 subgroups: high myopia (<−6D), low myopia (−6D to −1D), emmetropia (−1D to 1D), and hyperopia (>1D). After accounting for age, sex, and signal strength, multivariable regression showed strong dependence in most models for NFLT, GCCT, and NFLP-CD on axial eye length (AL), spherical equivalent (SE) refraction, and apparent optic disc diameter (DD). Optical analysis indicated that AL-related transverse optical magnification variations predominated over anatomic variations and were responsible for these trends. Compared to the emmetropic group, the false positive rates were significantly (Chi-square test P < 0.003) elevated in both myopia groups for NFLT, NFLP-CD, and GCCT. Regression-based adjustment of these diagnostic parameters with AL or SE significantly (McNemar test P < 0.03) reduced the elevated false positive rates.

Conclusions

Myopic eyes are biased to have lower NFLT, GCCT, and NFLP-CD measurements. AL- and SE-based adjustments were effective in mitigating this bias.

Translational Relevance

Adoption of these adjustments into commercial OCT systems may reduce false positive rates related to refractive error.

Assessment of macular structures and vascular characteristics in highly myopic anisometropia using swept-source optical coherence tomography angiography

Purpose: This study aimed to explore the macular structures and vascular characteristics of more myopic (MM) and contralateral eyes with highly myopic anisometropia.

Methods: Comprehensive ophthalmic examinations were performed for 33 patients with highly myopic anisometropia. Macular structures (total retinal layer [TRL], ganglion cell and inner plexiform layer [GCIPL], inner nuclear layer [INL], outer retinal layer [ORL], nerve fiber layer [NFL], choroidal layer [CHL]) and vascular characteristics (superficial vascular complex density [SVD], deep vascular complex density [DVD], choriocapillaris perfusion area [CCPA]) were assessed using swept-source optical coherence tomography (SS-OCT) and OCT angiography (OCTA). Macular structures and vascular characteristics of each subregion were compared to those of the Early Treatment of Diabetic Retinopathy Study (ETDRS).

Results: With highly myopic anisometropia, the thicknesses of the TRL, GCIPL, INL, and ORL in MM eyes were smaller than those in contralateral eyes in at least one quadrant of the perifoveal and parafoveal circles (all p &lt; 0.05), with no changes in the foveal and temporal quadrants of perifoveal regions (all p &gt; 0.05). A thicker NFL (p = 0.018) was found in MM eyes than in contralateral eyes in the superior perifoveal quadrant. The CHL (all p &lt; 0.05) in MM eyes was thinner in all regions than in the contralateral eyes according to the ETDRS. There were no statistical differences in the SVD, DVD, and CCPA of MM and contralateral eyes (all p &gt; 0.05).

Conclusion: All retinal layers, except the NFL, tended to be thinner in all subregions, except the temporal perifoveal and foveal quadrants in MM eyes, and choroidal thickness was thinned in all areas.

Hemodynamic and morphological changes of the central retinal artery in myopic eyes

Due to excessive elongation of the eyeball, myopia-related vascular abnormalities are frequently observed in the central retinal artery (CRA) and its intraretinal branches. In addition to inconsistency in previously reported findings, hemodynamic (reduced flow velocity, increased vascular resistance) and morphological changes (narrower vessel diameter) were usually studied separately. This cross-sectional study evaluated the hemodynamic and morphological characteristics concurrently in a large sample of healthy myopes, by using the color Doppler ultrasound and adaptive optics retinal camera. Results showed that the retrobulbar segment of CRA had a tendency of slightly reduced flow velocity in eyeballs with longer axial length, but the correlation was not significant after adjusting for the multiple correlations. Vascular resistance was not affected by the axial elongation. With respect to the intraretinal branches, no significant changes in longer eyes of total diameter or lumen diameter were observed, while both the wall thickness and the wall cross-sectional area were significantly increased, but only a marginally increase in the wall to lumen ratio was found with increasing axial length. This implies some potential small artery remodeling in the intraretinal CRA branches. Overall, blood supply of the inner retina in healthy young myopes is likely to be maintained. Additionally, morphological parameters of vascular microstructure could be potential biomarkers to monitor myopia progression and understand myopia-related vascular abnormalities in future studies.

Ocular and Hemodynamic Factors Contributing to the Central Visual Function in Glaucoma Patients With Myopia

Purpose

The purpose of this study was to investigate the ocular and hemodynamic factors contributing to the central visual function in glaucoma patients with myopia.

Methods

This study was a prospective observational study, which included 236 eyes of 140 patients with normal-tension glaucoma (NTG), which includes 114 eyes with mild myopia (axial length ≥24 and <26 mm) and 122 eyes with moderate-to-severe myopia (axial length ≥26 mm). Ocular characteristics were axial length and posterior pole profiles, including peripapillary atrophy (PPA) to disc area ratio, disc tilt ratio, disc torsion, and disc-foveal angle. Hemodynamic factors included standard deviation of the mean of qualified normal-to-normal intervals (SDNN) of a heart rate variability (HRV) test and vessel density (VD) parameters from optical coherence tomography angiography (OCTA). The root mean square error was estimated as a measure of the VD fluctuation. Association between ocular characteristics and VD parameters of the OCTA with the central sensitivity of the 10-degree visual field or the presence of central scotoma were analyzed.

Results

Deep layer VD of the peripapillary and macular areas showed significant differences between mild and moderate-to-severe myopia (P = 0.034 and P = 0.045, respectively). Structural parameters, especially PPA to disc area ratio, had significant correlation with peripapillary VD parameters in myopic eyes. Lower SDNN value (ß = 0.924, P = 0.011), lower deep VD of the macular area (ß = 0.845, P = 0.001), and greater fluctuation of deep VD in the peripapillary area (ß = 1.517, P = 0.005) were associated with the presence of central scotoma in patients with glaucoma with myopia in multivariate logistic regression analysis.

Conclusions

The structural changes by myopia, especially in the peripapillary region, affected VD parameters in myopic eyes. Lower deep VD and greater VD fluctuation in the peripapillary region showed association with central scotoma in patients with glaucoma with myopia, suggesting both structural and vascular changes by myopia may be related to central visual function in glaucoma patients with myopia.

Reduced Radial Peripapillary Capillary in Pathological Myopia Is Correlated With Visual Acuity

Purpose

To quantify the radial peripapillary capillary (RPC) density and the peripapillary retinal nerve fiber layer (pRNFL) thickness in pathological myopia and examine associations among these factors and best-corrected visual acuity (BCVA).

Methods

The cohort was composed of 41 eyes as control and 79 eyes with high myopia (59 simple high myopia, 20 pathological myopia). Optical coherence tomography angiography was done to obtain RPC density and pRNFL thickness, superficial retinal capillary plexus (SRCP), and deep retinal capillary plexus (DRCP) density. The axial length (AL) was measured. Correlations among BCVA, RPC density, pRNFL thickness, AL, and other parameters were determined.

Results

For pathological myopia, the densities of RPC, SRCP, and DRCP were significantly less than those of the control and simple high myopia groups (p ≤ 0.005). There was no statistical difference in pRNFL thickness between pathological myopia and simple high myopia (p = 0.063), whereas there was significant difference in global pRNFL thickness between pathological myopia and control (p = 0.008). The global RPC density showed the greatest area under the curve (AUC = 0.962, sensitivity = 94.74%, specificity = 90.00%, cutoff value = 47.8%) for pathological myopia, whereas the AUC of pRNFL thickness, SRCP, and DRCP were only 0.675, 0.824, and 0.865, respectively. The univariate and multiple linear regression models showed that RPC density, SRCP density, and AL were correlated with BCVA (All p < 0.05). In the final BCVA model with multiple generalized estimating equation analysis, AL, RPC density and interaction between RPC and AL were shown (all p < 0.03). For an eye with AL ≥ 27.94 mm, global RPC density was predicted to be less than 48.77% with a high risk of visual impairment.

Conclusion

Peripapillary alterations, both the decreasing RPC density and pRNFL thickness, occurred in pathological myopia compared with the control. The RPC density was associated with BCVA, and this relationship was affected by AL.

Investigation of Macular Structural and Microcirculatory Characteristics of Posterior Staphyloma in High Myopic Eyes by Swept Source Optical Coherence Tomography Angiography

Purpose: To investigate the characteristics of macular structures and microcirculation of posterior staphyloma (PS) and explored factors related to PS in eyes with high myopia.

Methods: There were 114 eyes of 82 patients in this study. Using 1:1 matching of the axial length of myopic eyes, patients were divided into no PS (NPS) and PS groups. Comprehensive ophthalmic examinations were performed on all patients. Structural parameters were acquired using swept source optical coherence tomography (SS-OCT). OCT angiography (OCTA) was used to measure the microcirculation parameters. Generalized estimated equation and linear correlation analysis were used for the statistical analysis.

Results: Patients with PS had a thinner retinal thickness (RT) and choroid thickness (CT) (all p < 0.05) in the measurement areas and a significantly lower subfoveal scleral thickness (SFST) (p < 0.001) than those without PS. Retinal deep vascular complex density (DVD) (all p < 0.05) and choriocapillaris perfusion area (CCPA) (all p < 0.001) were significantly lower in the measurement areas of the PS group than in those of the NPS group. There was no significant difference in the retinal superficial vascular density between the two groups. Generalized estimating equation indicated that SFST (B = 0.079, p = 0.001), parafoveal RT (B = −0.162, p = 0.041), foveal CT (B = 0.292, p = 0.013), parafoveal CT (B = −0.157, p = 0.023), foveal CCPA (B = 0.691, p = 0.003) and parafoveal CCPA (B = −0.026, p = 0.004) were significantly correlated with PS. Age (r = −0.323, p = 0.001), spherical equivalent refraction (SER) (r = 0.289, p = 0.004), subfoveal CT (r = 0.398, p < 0.001), foveal DVD (r = 0.346, p < 0.001), foveal CT (r = 0.429, p < 0.001), and foveal CCPA (r = 0.387, p < 0.001) were strongly correlated with SFST.

Conclusions: The macular structures and microcirculation in the PS group were different from those in the NPS group. SFST, CT, and CCPA were significantly correlated with PS. Lower SFST in PS was correlated with abnormalities of CT and microcirculation.

Systemic Vascular Dysregulation May Be Associated With Lower Peripapillary Vessel Density in Non-glaucomatous Healthy Eyes: A Prospective Cross-Sectional Study

Objective: To determine whether systemic vascular dysregulation (SVD) evaluated by nailfold capillaroscope and Flammer Syndrome Questionnaire (FSQ) affects retinal peripapillary microcirculation in non-glaucomatous healthy eyes at steady status. Methods: 120 healthy eyes from 63 non-glaucomatous subjects underwent Optical coherence tomography angiography (OCTA) after a rest of 30 minutes. Average retinal peripapillary capillary (RPC) vessel density (VD) and sectoral VD were automatically calculated, and peripapillary retinal nerve fiber layer thickness (RNFLT) was measured. Vasospastic diathesis was assessed using Flammer Syndrome Questionnaire (FSQ). Cold provocation test (CPT) was performed using nail-fold capillaroscope after OCTA. Positive CPT and a score of FSQ higher than 20% were necessary to determine a subject with SVD. Systemic and ocular parameters were compared between subjects with and without SVD. Results: In this study, heart rate (p = 0.042), ocular perfusion pressure (p = 0.014) and average RPC vessel density (p = 0.046) was significantly different between subjects with and without SVD determined by the combination of CPT and FSQ. Generalized estimation equation (GEE) showed lower VD was significantly associated with longer axial length (β = -0.352, p = 0.001), thinner peripapillary retinal nerve fiber layer thickness (RNFLT) (β = 0.296, p < 0.001), SVD determined by CPT and FSQ (β = 0.617, p = 0.003) and high blood pressure (β = -0.879, p < 0.001). In the superotemporal sector, multivariate model showed only SVD was associated with RPC vessel density (β = -0.811, p < 0.001). Conclusion: In subjects with SVD and non-glaucomatous healthy eyes, lower RPC vessel density in the superotemporal sector was observed. SVD determined by CPT and FSQ was significantly associated with attenuated retinal peripapillary microcirculation. Studies on ocular diseases relevant to vasospasms should consider the effects of SVD on the retinal peripapillary capillaries.

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.