Correlation of macular choroidal thickness with concentrations of aqueous vascular endothelial growth factor in high myopia

OCTA on the density of optic nerve microvessels in myopic population with ocular hypertension

OBJECTIVE

To measure functional, structural, and blood flow parameters of the optic disk in myopic patients with ocular hypertension (OHT) and myopic patients using optical coherence tomography angiography (OCTA), this study aims to investigate the variability of each parameter between the two groups, and to analyze the correlation between the RNFL thickness and blood flow parameters, as well as the diagnostic value of these blood flow parameters for myopic patients with OHT.

METHODS

This was a cross-sectional study. Myopic adults who were attending the Eye Center of Jinan Second People's Hospital between December 2020 and January 2022, and who had a confirmed diagnosis of OHT, were enrolled. This cohort constituted the myopic group. In these subjects, retinal nerve fiber layer (RNFL) thickness and blood flow parameters within the superficial optic disk 6 × 6 mm area were measured using OCTA. The optic disk blood flow parameters included radial peripapillary capillaries (RPC) perfusion density (PD) in nasal, temporal, superior, and inferior sectors. Visual field assessments were conducted using a Humphrey visual field meter to obtain the visual field index (VFI) and pattern standard deviation (PSD). SPSS 22.0 statistical software was utilized to determine if statistical differences existed between the parameters of the two groups and to analyze the correlation between blood flow parameters and RNFL thickness. Additionally, the area under the subject's operating characteristic curve (AUROC) was used to assess the diagnostic value of blood flow parameters for myopic patients with OHT.

RESULTS

There was no statistical difference in PSD and VFI in the OHT group compared with the myopic group (P = 0.351, 0.242). The RNFL thickness was (103.64 ± 8.13) μm and (97.56 ± 12.94) μm in the myopic and OHT groups, respectively. There was no statistical difference in RNFL thickness between the OHT and myopic group (P = 0.052). The PD of radial peripapillary capillaries (RPC) in nasal, temporal, superior, and inferior sectors showed an overall decreasing trend between the myopic and OHT groups, but there was a statistical difference only in the temporal sector (P = 0.008). Correlation analysis of blood flow parameters and structural parameters showed that the PD in the temporal sector and RNFL thickness were not correlated (P = 0.263). By plotting the AUROC of blood flow parameter, it was found that OCTA had good value in diagnosing myopic patients with OHT, and the PD of the temporal sector had higher diagnostic value for differentiating the OHT group from myopic group (AUROC = 0.718, P = 0.008) CONCLUSIONS: Compared with the myopic group, blood flow parameters decreased in the OHT group, while structural and functional parameters did not change significantly, suggesting that blood flow damage may have occurred earlier in myopic patients with OHT, by the correlation analysis between structural and blood flow parameters. OCTA has good diagnostic value for myopic patients with OHT.

Six-month repeated irradiation of 650 nm low-level red light reduces the risk of myopia in children: a randomized controlled trial

PURPOSE

To evaluate whether the six-month repeated irradiation of 650 nm low-level red light (LLRL) decreases the risk of myopia onset in children.

METHODS

This was a single-masked, randomized controlled trial. A total of 112 children (aged 6-12 years) were enrolled and randomized to the treatment group or control group in a 1:1 ratio. The cycloplegic spherical equivalent error (SER) of children at baseline was -0.5 diopter (D) to 3D. Children in the treatment group were irradiated with the 650 nm LLRL for 6 min daily. No intervention was given to the control. The primary outcomes are myopia incidence, change in cycloplegic SER, and change in axial length (AL).

RESULTS

For the treatment group and control group, the six-month myopia incidence rates were 1.8% (95% confidence interval, CI: 0.2-4.9%) and 12.5% (95% CI: 5.5-21.9%), respectively. The difference was significant (p = 0.028). The median changes in AL for the treatment group and control group were -0.02 (interquartile range, IQR: -0.12 to 0.06) mm, and 0.09 (IQR: 0-0.18) mm, respectively. The difference was significant (p < 0.001). The median changes in cycloplegic SER for the treatment group and control group were 0 (IQR: 0-0.25) D, and -0.125 (IQR: -0.375 to 0) D, respectively. The difference was significant (p < 0.001). There was no adverse event.

CONCLUSION

The repeated irradiation of 650 nm LLRL may have a strong effect for myopia prevention in children, without risk of adverse events.

TRIAL REGISTRATION

this trial is retrospectively registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ), the registration number is ChiCTR2200058963.

Vascular endothelial growth factor from retinal pigment epithelium is essential in choriocapillaris and axial length maintenance

Myopia, which prevalence is rapidly increasing, causes visual impairment; however, the onset mechanism of pathological axial length (AL) elongation remains unclear. A highly vascularized choroid between the retinal pigment epithelium (RPE) and sclera not only maintains physiological activities, but also contributes to ocular development and growth regulation. Vascular endothelial growth factor (VEGF) secreted from the RPE to the choroid is essential for retinal function and maintenance of the choriocapillaris. Herein, we demonstrated that the loss of VEGF secreted from the RPE caused abnormal choriocapillaris development and AL elongation, with features similar to those of the lens-induced myopia (LIM) mouse model, whereas VEGF overexpression by knocking-out von Hippel-Lindau (VHL) specific to the RPE expands the choriocapillaris and shortens the AL. Additionally, LDL Receptor Related Protein 2 (LRP2) deletion in the RPE downregulated VEGF expression and leads to pathological AL elongation. Furthermore, high-myopia patients without choriocapillaris demonstrated longer ALs than did those with preserved choriocapillaris. These results suggest that physiological secretion of VEGF from the RPE is required for proper AL development by maintaining the choriocapillaris. The pinpoint application of VEGF to the choriocapillaris may become a potential intervention for the prevention and treatment of axial myopia progression.

Effect of macular vascular density on visual quality in young myopic adults

Objective

To evaluate macular vascular density using optical coherence tomography angiography (OCTA) and to investigate its impact on best-corrected visual acuity (BCVA), contrast sensitivity function (CSF), and higher-order aberrations (HOAs) in young myopic adults.

Methods

This cross-sectional study included 109 eyes with axial length (AL) between 22 and 26 mm in the medium AL group and 90 eyes with AL > 26 mm in the long AL group. OCTA was used to obtain 3 × 3 mm en face images, and the vessel length density (VLD), perfusion density (PD), and fovea avascular zone (FAZ) of the superficial layer were evaluated. Visual quality was assessed using the CSF and HOAs.

Results

Significant differences were found in the inferior VLD, parafoveal PD, and FAZ areas between the groups. AL and macular vascular density showed negative correlations in the inferior and nasal areas. The spherical correction (SE) also showed a positive correlation with vascular density in these two areas. FAZ area and perimeter had a significant negative association with AL, and FAZ circularity was correlated with SE. CSF with bright around 6 and 12 spatial frequencies showed positive correlations with nasal PD. The parafoveal PD showed a significant correlation with BCVA after adjusting for other factors.

Conclusion

The superficial macular vascular density of young myopic adults decreased with lower SE and longer AL in the parafovea area. An eye with a long AL has a smaller FAZ, and myopia decreases the FAZ circularity index. The decrease in vessel density could contribute to worse BCVA and may be correlated with lower CSF, but not with HOAs.

Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy

Purpose

To examine the association of baseline choroidal sublayers metrics with the risk of diabetic retinopathy (DR) progression over 2 years, with adjustment for confounding factors that affect choroidal measurements.

Design

Prospective, observational cohort study.

Participants

One hundred three eyes from 62 patients with diabetes mellitus (DM).

Methods

Patients were followed up at 6-month intervals for at least 2 years. Choroidal metrics including choroidal area, choroidal thickness (CT), and choroidal vascularity index were measured for both (1) the choriocapillaris plus Sattler’s layer and (2) the Haller’s layer within the subfoveal and parafoveal region. Cox proportional models were constructed to estimate the relationship between baseline choroidal metrics and DR progression, adjusted for intereye correlation, established risk factors (i.e., duration of DM, glycated hemoglobin [HbA_1c] level, body mass index [BMI], use of insulin, and mean arterial blood pressure [MABP]) and confounding factors of choroidal measurements (i.e., age and axial length). Additional predictive value of choroidal metrics was assessed using the C-statistic.

Main Outcome Measures

Hazard ratios (HRs) calculated by Cox proportional hazards model to demonstrate the associations between baseline choroidal metrics and DR progression.

Results

After adjusting for age, axial length, and intereye correlation, choroidal metrics in Haller’s layer at baseline that were associated with a higher risk of DR progression included increases in subfoveal choroidal area (HR, 2.033; 95% confidence interval [CI], 1.179–3.505; P = 0.011), subfoveal plus parafoveal choroidal area (HR, 1.909; 95% CI, 1.096–3.326; P = 0.022), subfoveal CT (HR, 2.032; 95% CI, 1.181–3.498; P = 0.010), and subfoveal plus parafoveal CT (HR, 1.908; 95% CI, 1.097–3.319; P = 0.022). These associations remained statistically significant after additionally adjusting for duration of DM, HbA_1c level, BMI, use of insulin, and MABP. Addition of these choroidal metrics significantly improved the discrimination for DR progression when compared with established risk factors alone (e.g., duration of DM and HbA_1c; increase in C-statistic ranged from 8.08% to 9.67% [P < 0.05]).

Conclusions

Eyes with a larger choroidal area and CT in Haller’s layer at baseline were associated with a higher risk of DR progression over 2 years.

Myopia Alters the Structural Organization of the Retinal Vasculature, GFAP-Positive Glia, and Ganglion Cell Layer Thickness

To describe the effect of myopic eye growth on the structure and distribution of astrocytes, vasculature, and retinal nerve fiber layer thickness, which are critical for inner retinal tissue homeostasis and survival. Astrocyte and capillary distribution, retinal nerve fiber (RNFL), and ganglion cell layer (GCL) thicknesses were assessed using immunochemistry and spectral domain optical coherence tomography on eleven retinas of juvenile common marmosets (Callithrix Jacchus), six of which were induced with lens-induced myopia (refraction, Rx: -7.01 ± 1.8D). Five untreated age-matched juvenile marmoset retinas were used as controls (Rx: -0.74 ± 0.4D). Untreated marmoset eyes grew normally, their RNFL thickened and their astrocyte numbers were associated with RNFL thickness. Marmosets with induced myopia did not show this trend and, on the contrary, had reduced astrocyte numbers, increased GFAP-immunopositive staining, thinner RNFL, lower peripheral capillary branching, and increased numbers of string vessels. The myopic changes in retinal astrocytes, vasculature, and retinal nerve fiber layer thickness suggest a reorganization of the astrocyte and vascular templates during myopia development and progression. Whether these adaptations are beneficial or harmful to the retina remains to be investigated.

Macular Retinal Microvasculature of Hyperopia, Emmetropia, and Myopia in Children

Purpose

To compare macular retinal microcirculation in myopia, emmetropia, and hyperopia groups and investigate the relationship between macular retinal microcirculation and axial length (AL) in children.

Methods

Forty myopic, 29 emmetropic, and 34 hyperopic eyes were included. All the recruited eyes underwent optical coherence tomography angiography (OCTA) examinations. After adjusting the image size by the Littmann method and Bennett formula, the vessel density (VD) of the deep capillary plexus (DCP) and superficial vascular plexus (SVP) were assessed.

Results

The VD of the DCP was significantly lower in the myopia group than in the hyperopia group, whereas no significant differences in the VD of the SVP were observed among the myopia, emmetropia, and hyperopia groups. The VD of the DCP was significantly associated with AL, spherical equivalent (SE), and foveal retinal thickness (FRT), whereas the VD of the SVP was only significantly associated with FRT but not with AL or SE.

Conclusions

The myopic VD of the DCP was significantly lower than the hyperopic one, and the VD of the DCP was significantly associated with AL, indicating that myopia has a lower VD of the DCP, and AL could have a negative effect on the VD of the DCP. Thus, early myopic axial stretching might decrease retinal blood perfusion of the DCP in children.

Macular Choroidal Thickness and the Risk of Referable Diabetic Retinopathy in Type 2 Diabetes: A 2-Year Longitudinal Study

Purpose

The purpose of this study was to evaluate the associations between choroidal thickness (CT) and the 2-year incidence of referable diabetic retinopathy (RDR).

Methods

This was a prospective cohort study. Patients with type 2 diabetes in Guangzhou, China, aged 30 to 80 years underwent comprehensive examinations, including standard 7-field fundus photography. Macular CT was measured using a commercial swept-source optical coherence tomography (SS-OCT) device (DRI OCT Triton; Topcon, Tokyo, Japan). The relative risk (RR) with 95% confidence intervals (CIs) was used to quantify the association between CT and new-onset RDR. The prognostic value of CT was assessed using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

Results

A total of 1345 patients with diabetes were included in the study, and 120 (8.92%) of them had newly developed RDR at the 2-year follow-up. After adjusting for other factors, the increased RDR risk was associated with greater HbA1c (RR = 1.35, 95% CI = 1.17-1.55, P < 0.001), higher systolic blood pressure (SBP; RR = 1.02, 95% CI = 1.01-1.03, P = 0.005), lower triglyceride (TG) level (RR = 0.81, 95% CI = 0.69-0.96, P = 0.015), presence of diabetic retinopathy (DR; RR = 8.16, 95% CI = 4.47-14.89, P < 0.001), and thinner average CT (RR = 0.903, 95% CI = 0.871-0.935, P < 0.001). The addition of average CT improved NRI (0.464 ± 0.096, P < 0.001) and IDI (0.0321 ± 0.0068, P < 0.001) for risk of RDR, and it also improved the AUC from 0.708 (95% CI = 0.659-0.757) to 0.761 (95% CI = 0.719-0.804).

Conclusions

CT thinning measured by SS-OCT is an early imaging biomarker for the development of RDR, suggesting that alterations in CT play an essential role in DR occurrence.

The efficacy of different anti-vascular endothelial growth factor agents and prognostic biomarkers in monitoring of the treatment for myopic choroidal neovascularization

PURPOSE

To evaluate anatomical and visual results of eyes with naive myopic choroidal neovascularization (mCNV) in patients treated with intravitreal anti-vascular endothelial growth factor (VEGF) therapies.

MATERIAL AND METHODS

This is a retrospective, non-randomized, comperative, intervetional study. One hundred fourteen eyes of 114 patients with mCNV who underwent intravitreal bevacizumab (IVB), intravitreal ranibizumab (IVR) or intravitreal aflibercept (IVA) monotherapy injections were enrolled into the study. The best corrected visual acuity (BCVA), central macular thickness (CMT) and subfoveal choroidal thickness (SFCT) were compared among the groups during the follow-up periods at the beginning, months 1, 3, 6, 12, and the final visit.

RESULTS

The mean age of the patients was 47.76 ± 10.57 years (range, 33-72 years) and the mean follow-up period was 23.34 ± 6.81 months (range, 13-38 months). The mean BCVA denoted a significantly improve at each group (p < 0.05). In terms of an inter-group analysis of all 3 groups, at months 1, 6, and 12 and final visit, the BCVA were statistically significantly better in the IVA group when compared to both IVB and IVR groups (p = 0.021, p = 0.032, p = 0.024, p = 0.012). There was a significant decrease in CMT following IVB (236.49 ± 40.91 μm-190.74 ± 50.12 μm), IVA (232.91 ± 46.29 μm-193.73 ± 46.81 μm) and IVR (234.78 ± 45.37 μm-192.21 ± 37.27 μm) between baseline and final visit (p = 0.018, p = 0.002, p < 0.001, respectively). There was a statistically significant decrease in SFCT values between baseline and final examination only in the IVA group (p < 0.001). The mean number of injections were 9.18 ± 3.18 (range; 3 to 13) in IVB, 6.46 ± 2.93 (range; 3-11) in IVR and 4.45 ± 1.42 (range; 2-7) in IVA (p = 0.028).

CONCLUSION

All three anti-VEGFs were found to be effective in terms of visual results in patients with mCNV. However, we demonstrated that IVA reduces the need for anti-VEGF when compared to patients who received both IVB and IVR. Furthermore, IVA induced a prominent reduction in SFCT, whereas IVR and IVB did not have a significant action on SFCT.

The Deep Vascular Plexus Density is Closely Related to Myopic Severity

OBJECTIVES

To investigate the relationship between myopic severity and the retinal microvasculature based on quantitative variables using optical coherence tomography angiography (OCTA) and to identify OCTA indicators of microvascular network loss in myopia.

METHODS

This cross-sectional study included 123 eyes of 123 myopic subjects. The included eyes were divided into three groups according to the spherical equivalent (SE) and axial length (AL): low myopia (LM) (-3.00 D ≤ SE ≤ -0.50 D), moderate myopia (MM) (-6.00 D ≤ SE <-3.00 D) and high myopia (HM) (-9.00 D ≤ SE < -6.00 D or AL > 26 mm). All the eyes underwent OCTA scans. The densities and thicknesses of the macular and peripapillary zones, including the foveal avascular zone (FAZ) area, superficial vascular plexus (SVP) density, deep vascular plexus (DVP) density, ganglion cell complex (GCC) thickness, full retinal thickness, radial peripapillary capillary plexus (RPCP) density and retinal nerve fibre layer (RNFL) thickness, were automatically exported.

RESULTS

Compared to the LM or MM group, the HM group had a significantly reduced FAZ area (p < 0.05). In most sectors of the parafoveal and perifoveal areas, the HM group had significantly lower DVP density and higher retinal thickness than the LM and MM groups (all p < 0.05). However, significant differences among the three groups in only one or several sectors were observed with regard to SVP density, GCC thickness and RNFL thickness, and no significant differences among the three groups in any sector were noticed in RPCP density. Perifoveal DVP density and perifoveal full retinal thickness were positively associated with SE and negatively associated with AL in stepwise multiple linear regression analyses adjusted for sex and age.

CONCLUSION

DVP density was closely related to myopic severity. Reduced perifoveal DVP density may serve as an indicator of microvascular network loss in myopia. OCTA may provide useful and crucial information for monitoring the progression of myopia.

The influence of the choroid on the onset and development of myopia: from perspectives of choroidal thickness and blood flow

Myopia is the most common type of refractive errors characterized by excessive elongation of the ocular globe. With the increasing prevalence of myopia, improved knowledge of factors involved in myopia development is of particular importance. There are growing evidence suggesting that the choroid plays an important role in the regulation of eye growth and the development of myopia. Studies have demonstrated that thinning choroid is a structural feature of myopia, with a negative correlation between choroidal thickness and axial length, suggesting that the change in choroidal thickness may be a predictive biomarker for long-term changes in ocular elongation. Given the fact that the choroid is primarily a vascular structure capable of rapidly changing blood flow, variations of choroidal thickness might be primarily caused by changes in choroidal blood flow. Considering that hypoxia is associated with myopia and choroidal blood flow is the main source of oxygen and nourishment supply, apart from the effect on myopia possibly by changing choroidal thickness, decreasing choroidal blood flow may contribute to scleral ischaemia and hypoxia, resulting in alterations in the scleral structure and thus leading to myopia. This review aims to provide an overview of recent work exploring the influence of the choroid on myopia from perspectives of choroidal thickness and blood flow, which may present new predictive indicators for the onset of myopia and new targets for the development of novel therapeutic approaches for myopia.

Association of Myopia With Microvascular Alterations in Patients With Type 2 Diabetes: An Optical Coherence Tomography Angiography Study

Purpose: To determine the association of myopia with peripapillary and macular microvasculature in eyes with type 2 diabetes using optical coherence tomography angiography (OCTA). Methods: Diabetic patients with and without diabetic retinopathy (DR) were recruited and grouped according to myopic status in this cross-sectional study. Axial length, refractive error, and OCTA parameters were measured. OCTA parameters were analyzed with adjustment of confounding factors and further Bonferroni analysis was performed to determine the differences in multiple group comparisons. Results: Compared with the diabetic eyes without myopia, those with myopia had lower rate of DR (21.82 vs. 35.90%, χ2 = 6.190, P = 0.013), longer axial lengths (24.94 ± 0.75 vs. 23.16 ± 0.64, F = 311.055, P < 0.001) and reduced whole vessel density (VD) of optic nerve head (ONH) (45.89 ± 5.76 vs. 49.14 ± 4.33, F = 19.052, P < 0.001), peripapillary VD (48.75 ± 6.56 vs. 50.76 ± 4.51, F = 7.600, P = 0.006), and reduced thickness of the retinal nerve fiber layer (RNFL) (95.50 ± 12.35 vs. 100.67 ± 13.68, F = 5.020, P = 0.026). In eyes without myopia, the superficial vessel density (SVD) (46.58 ± 4.90 vs. 43.01 ± 4.25; 95% CI, 1.80-4.61; P < 0.001), deep vessel density (DVD) (45.64 ± 6.34 vs. 42.15 ± 6.31; 95% CI, 1.07-5.00; P < 0.001), and FD300 area density (50.31 ± 5.74 vs. 44.95 ± 6.96; 95% CI, 2.88-7.27; P < 0.001) were significant reduced in eyes with DR(DR eyes) comparing to those without DR (NoDR eyes). In eyes with myopia, only SVD were significantly reduced in DR eyes comparing to NoDR eyes (41.68 ± 3.34 vs. 45.99 ± 4.17; 95% CI, 1.10-7.22; P = 0.002). In NoDR eyes, both whole VD of ONH and Peripapillary VD demonstrated a significant decrease in eyes with myopia comparing to those without myopia (49.91 ± 4.36 vs. 45.61 ± 6.32; 95% CI, 1.95-6.27; P < 0.001 and 51.36 ± 4.24 vs. 48.52 ± 6.99; 95% CI, 0.56-5.11; P = 0.006, respectively). Conclusions: In diabetic patients, myopic eyes exhibited lower prevalence of DR and thinner thickness of RNFL. The refractive status could possibly impact the retinal microvascular changes from NoDR to DR stage.

Association of Myopia with Peripapillary Retinal Nerve Fiber Layer Thickness in Diabetic Patients Without Diabetic Retinopathy

Purpose

To investigate the association between myopia and peripapillary retinal nerve fiber layer (pRNFL) thickness in diabetic patients without diabetic retinopathy (DR).

Methods

A total of 271 eyes of 271 participants were included. They were divided into four groups according to the presence of myopia (≤ -3 diopters [D]) and diabetes without DR: (1) control group (n = 76), (2) myopia group (n = 57), (3) diabetes group (n = 82), and (4) diabetes + myopia group (n = 56). The peripapillary average and sector RNFL thicknesses were measured and compared among the four groups to determine the effects of myopia and diabetes. Covariates were adjusted using analyses of covariance. Linear regression analyses were fitted to evaluate the factors associated with pRNFL.

Results

Spherical equivalents were 0.12 ± 1.31 D in the control group, -4.00 ± 1.47 D in the myopia group, 0.00 ± 1.05 D in the diabetes group, and -4.33 ± 1.70 D in the diabetes + myopia group (P < 0.001). The respective axial lengths (ALs) were 23.91 ± 0.99 mm, 25.16 ± 0.94 mm, 23.68 ± 0.77 mm, and 25.34 ± 1.33 mm (P < 0.001). The average pRNFL showed a progressive decrease from the control group (97.16 ± 8.73 µm) to the myopia group (94.04 ± 9.13 µm) to the diabetes group (93.33 ± 9.07 µm) to the diabetes + myopia group (91.25 ± 9.72 µm) (P = 0.009). Age, diabetes, hypertension, and AL were significantly correlated with the pRNFL. The rate of reduction of pRNFL with increasing age was higher in the diabetes + myopia group than in the other groups, and pRNFL in the diabetes groups decreased more steeply with increasing AL compared to the non-diabetic groups.

Conclusions

Myopia and diabetes are important factors affecting pRNFL thickness, and the simultaneous presence of diabetes and myopia results in greater pRNFL damage than observed with either pathology alone.

The Role of C-Jun N-terminal Kinase-1 in Controlling Aquaporin-1 and Choroidal Thickness during Recovery from Form-deprivation Myopia in Guinea Pigs

PURPOSE

The development and recovery(REC) of myopia is associated with changing of choroidal thickness(CT) in model of guinea pigs. Aquaporin-1 (AQP-1) is related to the changes of CT during the recovery from myopia, but the corresponding signaling pathway has not been clarified. This study aimed to investigate the effect of JNK1 on CT/AQP-1 and the recovery from myopia.

MATERIALS AND METHODS

According to the different single intravitreal injections in eyes that underwent form deprivation for 21 days, guinea pigs were divided into four groups: the REC group, the REC+anisomycin (REC-AN, agonist for JNK1, 0.2 nmol) group, the REC+SP600125 (REC-SP, inhibitor for JNK1, 0.2 nmol) group, and the REC+dimethyl sulfoxide (REC-DM) group. Each group was divided into three subgroups based on the duration of the form deprivation: 3 days (d), 7 d and 10 d. All animals underwent biometric measurements (refractive error, axial length (AL), and CT), and the protein expression of AQP-1 and p-JNK1 in the choroid was also measured.

RESULTS

In REC and REC-DM groups, significant differences in CT/refractive error/AL/p-JNK1 or AQP-1 were only found in the 3d group compared with normal control (NC) group (all p < .05). In REC-AN group, CT/p-JNK1 or AQP-1 in 3d group was significantly higher than that in other 3d groups (all p < .05), but no significant difference in refractive error or AL was found compared with NC group at three time points (all p > .05). In REC-SP group, a significant difference in refractive error/CT/p-JNK1 or AQP1 was found in 3d/7d group compared with NC group (all p < .05), but AL was only found in 3d groups (p = .001).

CONCLUSIONS

Changes in JNK1 phosphorylation can regulate AQP-1 and CT during the recovery from myopia and the recovery time. Thus, JNK1 may be a potential therapeutic target for preventing/treating myopia.

Impact of Axial Eye Size on Retinal Microvasculature Density in the Macular Region

Mechanical tissue stresses are important contributors to the increased risk of sight-threatening pathology in larger, more myopic eyes. The contribution of altered ocular vasculature to the development of this pathology is less well defined. The current study investigated the impact of eye size on the superficial vasculature of the macula. Subjects (n = 104) aged 18–50, with no history of ocular or vascular disease, or myopia control, were recruited from university staff and student populations in Australia and Hong Kong. Refractive error, ocular size, retinal morphology and vascular morphology were quantified through open field autorefraction, ocular biometry and ocular coherence tomography angiography. Morphology of the superficial retinal capillary plexus was assessed over a 3 × 3 mm fovea-centred area. Perfusion area and vessel length densities were analysed relative to axial eye length and retinal thickness. A significant inverse association was found between axial length and vascular density measures (perfusion area density r² = 0.186, p < 0.001; and vessel length density r² = 0.102, p = 0.001). Perfusion area and vessel length densities were reduced by 5.8% (p = 0.001) in the longest, relative to the shortest, eyes. The aggregated ganglion cell layer inner plexiform layer thickness was also inversely associated with eye size (r² = 0.083, p = 0.003), and reduced, by 8.1% (p < 0.001), in the longest eyes. An inverse association of eye size and superficial retinal vasculature density, that is not simply explained by retinal expansion or image magnification factors, was confirmed. These data support the hypothesis that ongoing metabolic challenges may underlie the development of myopia-related and -associated pathology in larger eyes.

Relationship between Aquaporin-1 Protein Expression and Choroidal Thickness during the Recovery of Form-deprivation Myopia in Guinea Pigs

Purpose: The purpose of this study was to investigate the relationship between aquaporin-1 (AQP-1) protein expression in the choroid and choroid thickness (CT) during the recovery of form-deprivation (FD) myopia in guinea pigs.Materials and Methods: Seventy-two guinea pigs were randomly assigned to the normal control (NC) group, FD 21 group (animals wore a latex facemask in the right eye for 21 days to induce FD myopia) and four recovery (REC) groups. Guinea pigs in the REC groups also wore the facemask for 21 days to induce myopia; then, the facemask was removed, and the eye was re-exposed to the normal environment for 12 hours (REC ½ group), 1 day (REC 1 group), 2 days (REC 2 group), and 7 days (REC 7 group). All animals underwent biometric measurements (refraction, axial length, and CT), and the protein expression of AQP-1 in the choroid was determined using western blotting.Results: The protein expression of AQP-1 and CT were significantly decreased in the FD 21 group as compared with those in the NC group (p = .007 and p < .001). Both AQP-1 protein expression and CT gradually increased and peaked in the REC 2 group. Additionally, there were significant differences in AQP-1 protein expression and CT between the REC 2 group and all other groups (all p < .05). We observed a complete recovery in the in REC 7 group as compared with the NC group (p > .05). AQP-1 protein expression was significantly associated with CT (p = .001) in all groups; however, there was a significant negative correlation (p = .029) between AQP-1 protein expression and axial length in the REC groups.Conclusions: AQP-1 protein expression in the choroid was upregulated following recovery of FD myopia in guinea pigs, and these changes correlated with alterations in CT and axial length.

Correlation of axial length and myopic macular degeneration to levels of molecular factors in the aqueous

To elucidate the molecular processes associated with the development of myopic macular degeneration (MMD), we measured the intraocular concentrations of molecular factors in emmetropic and myopic eyes. This is a retrospective clinic-based case-control study that included eyes undergoing routine cataract surgery whereby aqueous humour samples were obtained. We measured the concentrations of pigment epithelium derived factor(PEDF), matrix metalloproteinase 2(MMP-2), tissue inhibitor of metalloproteinase(TIMP-2), vascular endothelial growth factor isoform A(VEGF-A), interleukin 8(IL-8), interleukin 6(IL-6), C-reactive protein(CRP), angiopoietin 2(Ang2), and amphiregulin. 38 eyes (axial length (AL): 22.4–32.4 mm), including 12 highly myopic (HM) eyes (AL ≥ 26.5 mm) without MMD and 12 HM eyes with MMD but without neovascularization were included. Eyes with MMD were found to have significantly lower VEGF-A levels (p = 0.007) and higher MMP-2 levels (p = 0.02) than control eyes after adjusting for age and gender. MMP-2 levels correlated positively (r = 0.58, p = 0.002), while VEGF-A levels correlated negatively with longer axial length (r = −0.75, p < 0.001). Both the concentrations of VEGF-A (P = 0.25) and MMP-2 (P = 0.69) were not significantly associated with MMD after adjusting for AL. These findings suggest that the predominant mechanism underlying the development of non-neovascular MMD may be axial elongation, driven in part by MMP-2 related mechanisms.

Association of Myopia With Peripapillary Perfused Capillary Density in Patients With Glaucoma: An Optical Coherence Tomography Angiography Study

Importance

This study used optical coherence tomographic angiography to assess for impaired blood flow in myopic eyes with or without open-angle glaucoma.

Objective

To compare the peripapillary perfused capillary density (PCD) between eyes with and without glaucoma.

Design, Setting, and Participants

In this cross-sectional study at a tertiary glaucoma referral practice, we recruited patients with myopic eyes of spherical equivalent of more than -3.0 diopters with and without open-angle glaucoma, patients with nonmyopic eyes with glaucoma, and patients with no disease from February 2016 to October 2016. We obtained 4.5 × 4.5-mm optical coherence tomographic angiography images of the optic nerve head and calculated PCD as the ratio of pixels associated with capillaries to the number of pixels in the region of interest after large blood vessel removal. Both eyes of each patient were used in the analysis. Continuous variables were assessed by analysis of variance and Tukey tests. A marginal model of generalized estimating equations was performed to adjust for confounding factors and intraclass correlations.

Main Outcomes and Measures

Mean PCD.

Results

We matched 87 patients with myopic eyes with glaucoma (of whom 39 [45%] were women), 17 with myopic eyes without glaucoma (of whom 10 [59%] were women), and 93 with non-myopic eyes with glaucoma (of whom 55 [59%] were women) for visual field defects and included 51 control participants (or whom 38 [75%] were women). Mean (SD) ages were 67.5 (12.0) years for patients with myopia and glaucoma, 48.2 (19.0) years for those with myopia without glaucoma, 67.3 (11.0) years for those with glaucoma without myopia, and 64.7 (8.9) years in control participants. Global PCD demonstrated a progressive decrease from the control group (mean [SD], 41.0 [4.2]) to those with myopia without glaucoma (38.4 [5.8]) to those with glaucoma without myopia (31.9 [7.5]) to those with both (28.2 [6.0]; all P < .001). The mean difference in global PCD between the 3 groups and control group, adjusted for age and axial length, was greatest in those with myopia and glaucoma (-11.1; 95% CI, -14.0 to -8.1; P < .001), followed by those with glaucoma without myopia (-8.6; 95% CI, -10.9 to -6.3; P < .001) and those with myopia without glaucoma (-2.8; 95% CI, -6.9 to 1.2; P = .17). No interaction was found between glaucoma and myopia.

Conclusions and Relevance

These findings demonstrate peripapillary microvascular attenuation to a greater extent in open-angle glaucoma than myopia. The cross-sectional design means we cannot determine if this association is a cause and/or is associated with other confounding factors.

Macular choroidal thickness in highly myopic women during pregnancy and postpartum: a longitudinal study

Background

High myopia, a cause of serious visual impairment, is a significant global public health concern. We investigate longitudinal changes in macular choroidal thickness (CT) during pregnancy and 6-months postpartum in women with high myopia (HM).

Methods

A prospective longitudinal study was conducted in HM-pregnant women during the course of pregnancy (n = 42 eyes, 42 patients) and 6 months postpartum (n = 40 eyes, 40 patients, two cases lost).Macular CT was measured via enhanced-depth imaging (EDI)-optical coherence tomography (OCT) (EDI-OCT). Intraocular pressure (IOP), axial length (AL), refractive error, mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), and body mass index (BMI) were also measured.

Results

Macular CTs of HM pregnant women (214.3 ± 52.3 μm) had increased significantly during the third trimester of pregnancy compared with postpartum women (192.7 ± 51.9 μm, p = 0.014). No significant differences in AL, refractive error, or MAP were found between pregnant and postpartum groups (p > 0.05 for all parameters).During pregnancy, macular CT was negatively correlated with AL (first trimester: p = 0.010; second trimester: p = 0.013; and third trimester: p = 0.008) and positively correlated with refractive error (first trimester: p = 0.038; second trimester: p = 0.024; and third trimester: p = 0.010). No correlations between macular CT and age, IOP, MOPP, MAP, or BMI were found.

Conclusions

Our study revealed the presence of a significantly thicker choroid during the third trimester of pregnancy compared with 6-mo postpartum in HM women. Macular CT positively correlated with refractive error and negatively correlated with AL during pregnancy, but did not correlate with gestational age, MOPP, IOP, MAP, or BMI.

Peripapillary Perfused Capillary Density in Exfoliation Syndrome and Exfoliation Glaucoma versus POAG and Healthy Controls: An OCTA Study

PURPOSE

To compare the peripapillary perfused capillary density (PCD) among eyes with exfoliation syndrome (XFS), exfoliation glaucoma (XFG), primary open-angle glaucoma (POAG), and controls.

DESIGN

Observational, cross-sectional study.

METHODS

Optical coherence tomography angiography (OCTA) images (4.5×4.5 mm) of the optic nerve head were obtained using a commercial spectral domain OCTA system (AngioVue Avanti RTVue-XR, OptoVue, Fremont, CA). Two concentric circles with 1.95-mm (inner) and 3.45-mm (outer) diameters were placed manually, producing an annulus of width 0.75 mm centered at the optic disc. PCD was calculated as the ratio of pixels associated with capillaries to the pixels in the annulus after large blood vessel removal. Continuous variables were assessed by analysis of variance and Tukey honest significant difference (HSD) test. Multiple linear regression analysis was performed to adjust for confounding factors.

RESULTS

Forty-three XFG eyes, 31 POAG eyes matched for visual field mean deviation, 33 XFS eyes, and 45 control eyes were analyzed. PCD demonstrated a progressive decrease from controls to XFS to POAG to XFG. Pairwise comparisons revealed significant differences in PCD between each pair of groups (all P<0.01) except for PCD between XFS and POAG (P = 0.08). A multivariable model adjusting for age and stage showed a more significant decrease in PCD in XFG compared with POAG (P = 0.001).

CONCLUSIONS

PCD was more significantly decreased in XFG compared with POAG eyes and in XFS compared with control eyes. OCTA provides the first quantitative evidence of the microvascular disturbance that accompanies XFS.

Sex-Dependent Choroidal Thickness Differences in Healthy Adults: A Study Based on Original and Synthesized Data

PURPOSE

The purpose of this study is to determine the influence of sex on choroidal thickness (CT) in healthy adults.

METHODS

Healthy Chinese adults were recruited and complete ophthalmic examinations were performed. The choroid was imaged by swept-source optical coherence tomography and the macular CT in Early Treatment Diabetic Retinopathy Study grids was obtained by the intrinsic automated segmentation software. CT in males and females was compared after controlling other factors. All of the published studies in PubMed were systemically tracked, and a syntheses analysis of the combined data of the present study and previous studies was performed to address this issue further.

RESULTS

A total of 104 healthy adults were included, of whom 38 (37%) were male and 66 (63%) were female. Older age and longer axial length (AL) each were significantly associated with thinner CT. After controlling for age and AL, the foveal CT and average macular CT were 25.5 μm (95% CI: 0.5-50.4 μm) and 22.1 μm (95% CI: 2.7-41.4 μm) thicker in men than in women, respectively. Significant differences in CT between males and females were also observed in inner and outer rings after controlling for age and AL (P < 0.05). After strict screening, 15 previously reported studies were determined to be eligible for inclusion. The combination of data collected from 2821 males and 3389 females provided further evidence that the choroid is thicker in males, with a pooled mean difference of 19.5 μm (95% CI: 11.4 to 27.6) for foveal CT and 14.7 μm (95% CI: 6.8 to 22.6) for average CT.

CONCLUSION

Our study of Chinese subjects, along with the syntheses analysis, strengthens the evidence that CT is greater in males than in females, based on OCT measurements. This observation may be pertinent for the sex disparities in some clinical conditions related to CT.

The linear artifact in enhanced depth imaging spectral domain optical coherence tomography

Optical coherence tomography (OCT) is a valuable ancillary test in the diagnosis and management of chorioretinal disease. The evaluation of choroid thickness using OCT has become the focus of clinical applications. We report a linear artifact that acts as a confounding factor in choroidal thickness measurements by enhanced depth imaging OCT. We found that the linear artifact is located stably at a depth of 485 μm beneath the retinal pigment epithelium in 81.88% of subjects. The study suggested that the linear artifact was a confounding factor in assessing choroidal thickness and that caution should be used in the interpretation of the choroidal thickness, especially when it is approximately 485 μm.

Retinal Microvascular Network and Microcirculation Assessments in High Myopia

PURPOSE

To investigate the changes of the retinal microvascular network and microcirculation in high myopia.

DESIGN

A cross-sectional, matched, comparative clinical study.

PARTICIPANTS

Twenty eyes of 20 subjects with nonpathological high myopia (28 ± 5 years of age) with a refractive error of -6.31 ± 1.23 D (mean ± SD) and 20 eyes of 20 age- and sex-matched control subjects (30 ± 6 years of age) with a refractive error of -1.40 ± 1.00 D were recruited.

METHODS

Optical coherence tomography angiography (OCTA) was used to image the retinal microvascular network, which was later quantified by fractal analysis (box counting [D_box], representing vessel density) in both superficial and deep vascular plexuses. The Retinal Function Imager was used to image the retinal microvessel blood flow velocity (BFV). The BFV and microvascular density in the myopia group were corrected for ocular magnification using Bennett's formula.

RESULTS

The density of both superficial and deep microvascular plexuses was significantly decreased in the myopia group in comparison to the controls (P < .05). The decrease of the microvessel density of the annular zone (0.6-2.5 mm), measured as D_box, was 2.1% and 2.9% in the superficial and deep vascular plexuses, respectively. Microvessel density reached a plateau from 0.5 mm to 1.25 mm from the fovea in both groups, but that in the myopic group was about 3% lower than the control group. No significant differences were detected between the groups in retinal microvascular BFV in either arterioles or venules (P > .05). Microvascular densities in both superficial (r = -0.45, P = .047) and deep (r = -0.54, P = .01) vascular plexuses were negatively correlated with the axial lengths in the myopic eye. No correlations were observed between BFV and vessel density (P > .05).

CONCLUSIONS

Retinal microvascular decrease was observed in the high myopia subjects, whereas the retinal microvessel BFV remained unchanged. The retinal microvascular network alteration may be attributed to ocular elongation that occurs with the progression of myopia. The novel quantitative analyses of the retinal microvasculature may help to characterize the underlying pathophysiology of myopia and enable early detection and prevention of myopic retinopathy.

Repeatability of Choroidal Thickness Measurements on Enhanced Depth Imaging Optical Coherence Tomography Using Different Posterior Boundaries

PURPOSE

To assess the reliability of manual choroidal thickness measurements by comparing different posterior boundary definitions of the choroidal-scleral junction on enhanced depth imaging optical coherence tomography (EDI-OCT).

DESIGN

Reliability analysis.

METHODS

Two graders marked the choroidal-scleral junction with segmentation software using different posterior boundaries: (1) the outer border of the choroidal vessel lumen, (2) the outer border of the choroid stroma, and (3) the inner border of the sclera, to measure the vascular choroidal thickness (VCT), stromal choroidal thickness (SCT), and total choroidal thickness (TCT), respectively. Measurements were taken at 0.5-mm intervals from 1.5 mm nasal to 1.5 mm temporal to the fovea, and averaged continuously across the central 3 mm of the macula. Intraclass correlation coefficient (ICC) and coefficient of reliability (CR) were compared to assess intergrader and intragrader reliability.

RESULTS

Choroidal thickness measurements varied significantly with different posterior boundaries (P < .001 for all). Intergrader ICCs were greater for SCT (0.959-0.980) than for TCT (0.928-0.963) and VCT (0.750-0.869), even in eyes where choroidal-scleral junction visibility was <75%. Intergrader CRs were lower for SCT (41.40-62.31) than for TCT (61.13-74.24) or VCT (72.44-115.11). ICCs and CRs showed greater reliability for averaged VCT, SCT, or TCT measurements than at individual locations. Intragrader ICCs and CRs were comparable to intergrader values.

CONCLUSIONS

Choroidal thickness measurements are more reproducible when measured to the border of the choroid stroma (SCT) than the vascular lumen (VCT) or sclera (TCT).

Impact of Valsalva maneuver on central choroid, central macula, and disk fiber layer thickness among high myopic and hyperopic patients

PURPOSE

To evaluate the alterations in mean central choroidal, central macular, and disk retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) during Valsalva maneuver among patients with high refractive errors.

METHODS

A total of 60 high myopic (≥-6.0 D) and 50 high hyperopic (≥ + 3.0 D) eyes of 58 patients aged 19-65 years with visual acuity of 20/20 and without any ophthalmologic or systemic diseases were evaluated by OCT before and after the Valsalva maneuver. The choroidal thickness was measured with enhanced depth imaging OCT method. Central macular thickness, disk RNFL thickness, and axial length were also assessed.

RESULTS

Mean choroidal thickness increased significantly from 275.0 ± 27.2 μm at rest to 279.8 ± 31.6 μm after Valsalva maneuver in high myopic patients, and from 308.2 ± 27.3 μm to 313.6 ± 28.5 μm in high hyperopic patients (p<0.01 for each). A significant negative correlation of the choroidal thickness was noted with axial length (r = -0.509, p<0.01) and age (r = -0.224, p = 0.01) in the overall study population. Mean central macular thickness was 242.9 ± 44.4 μm and 254.0 ± 22.8 μm, while mean disk RNFL thickness was 81.6 ± 12.4 μm and 98.4 ± 13.3 μm in high myopic and hyperopic patients, respectively. Valsalva maneuver was not associated with significant change in central macular or disk RNFL thickness.

CONCLUSIONS

Significant association of Valsalva maneuver with an increase in choroidal thickness was noted among patients with high degree of myopia and hyperopia. Our findings emphasize the likelihood of increase in choroidal volume due to venous distension to be responsible for the increase observed in choroidal thickness after Valsalva maneuver.

Aqueous Levels of Pigment Epithelium-Derived Factor and Macular Choroidal Thickness in High Myopia

Purpose. To investigate the correlation between aqueous and serum levels of pigment epithelium-derived factor (PEDF) and macular choroidal thickness in high myopia patients, both with and without choroidal neovascularization (CNV). Methods. Serum and aqueous levels of PEDF were measured by enzyme-linked immunosorbent assay in 36 high myopia patients (36 eyes) with no CNV (non-CNV group), 14 high myopia patients (14 eyes) with CNV (CNV group), and 42 nonmyopia patients (42 eyes) (control group). Macular choroidal thickness was measured by enhanced-depth imaging optical coherence tomography. Results. Aqueous levels of PEDF were significantly higher in CNV group compared with non-CNV (P < 0.001) and control (P < 0.001) groups. Macular choroidal thicknesses were significantly decreased in the non-CNV and CNV groups compared with the control (P < 0.001) group. A statistically significant difference (P = 0.012) was found between the CNV and non-CNV groups. There was a positive correlation between aqueous PEDF and macular choroidal thickness in the non-CNV group (P = 0.005), but no correlation with the CNV group. No correlation between serum PEDF and macular choroidal thickness was detected in the three groups. Conclusion. Variations in aqueous PEDF levels coincide with changes in macular choroidal thickness in high myopia patients with no CNV, while no such relationship exists in high myopia patients with CNV.

Choroidal thickness and high myopia: a cross-sectional study and meta-analysis

Background

The purpose of this study was to examine the choroidal thickness of patients with high myopia using enhanced depth imaging optical coherence tomography (EDI-OCT) and compare them with healthy subjects.

Methods

We first conducted a cross-sectional study and then performed a meta-analysis to address this issue further. Using enhanced depth imaging optical coherence tomography (EDI-OCT), the macular choroidal thickness of high myopic eyes and normal control eyes were measured and compared at each location. Univariate and multivariate linear regression analyses were performed to assess the association between choroidal thickness and clinical factors such as axial length (AL), spherical equivalent (SE), and central corneal thickness. In the high myopic eyes, subgroup analysis of macular choroidal thickness was performed in eyes with or without lacquer cracks and choroidal neovascularization (CNV). The meta-analyses were conducted using the Stata software package.

Results

The high myopic eyes had a thinner choroid than the control eyes at all macular locations (all P < 0.001). Multivariable linear regression analysis showed that the subfoveal choroidal thickness (SFCT) was not significantly thinner in association with the diagnosis. Subgroup analysis showed that the high myopia with CNV and with lacquer cracks had a significantly thinner choroid than without CNV or lacquer crack eyes. The result of our cross-sectional study is consistent with the results of the further meta-analysis with the pooled weighted mean difference (WMD) of −116.30 μm (95 % CI: −145.68, −86.92) for SFCT.

Conclusions

The present study, along with the comprehensive meta-analysis, indicated that in the Chinese population, the choroidal thickness in high myopic eyes was thinner than that of normal control eyes, even across different subgroups. This might be secondary to the longer AL but it is not an independent factor. The presence of CNV and of lacquer cracks is associated strongly with eyes with thinner macular choroids.