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

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

Purpose

This study aims to investigate the impact of axial elongation on ganglion cell complex thickness (GCCT) and retinal capillary density (CD) using wide-field swept-source optical coherence tomography angiography.

Methods

A retrospective cross-sectional analysis was conducted involving 506 eyes. Fovea-centered scans were obtained to assess the subregional GCCT and capillary density across the whole retina, the superficial capillary plexus (SCP), and deep capillary plexus (DCP) among three groups: normal control, high myopia (HM) eyes with axial length < 28 mm, and HM eyes with axial length > 28 mm. Regional variations (central vs. peripheral, quadrants difference [superior, inferior, nasal, and temporal]) were analyzed.

Results

In HM eyes with axial length > 28 mm, GCCT and retinal CD exhibit a general decline in most regions (P < 0.05). In HM eyes with axial length < 28 mm, significant reductions were observed specifically in peripheral regions, as in the GCCT beyond the 3 × 3 mm2 area and CD in the 9-12 mm whole retina, 9-12 mm superior SCP, and 6-12 mm DCP (P < 0.05). Maximum GCCT and retinal CD reduction with axial elongation was observed in subregions beyond 6 × 6  mm2.

Conclusions

GCCT beyond the 3 × 3 mm2 area and peripheral retinal CD beyond the 6 × 6  mm2 area were more susceptible to axial elongation and are thereby deserving of particular attention.

Translational Relevance

It is necessary to evaluate different regions during the clinical assessment of the effect of myopia on the fundus and pay close attention to the peripheral retina.

Diagnostic Capability of OCTA-Derived Macular Biomarkers for Early to Moderate Primary Open Angle Glaucoma

Background/Objectives: To investigate macular vascular biomarkers for the detection of primary open-angle glaucoma (POAG). Methods: A total of 56 POAG patients and 94 non-glaucomatous controls underwent optical coherence tomography angiography (OCTA) assessment of macular vessel density (VD) in the superficial (SCP), and deep (DCP) capillary plexus, foveal avascular zone (FAZ) area, perimeter, VD, choriocapillaris and outer retina flow area. POAG patients were classified for severity based on the Glaucoma Staging System 2 of Brusini. ANCOVA comparisons adjusted for age, sex, race, hypertension, diabetes, and areas under the receiver operating characteristic curves (AUCs) for POAG/control differentiation were compared using the DeLong method. Results: Global, hemispheric, and quadrant SCP VD was significantly lower in POAG patients in the whole image, parafovea, and perifovea (p < 0.001). No significant differences were found between POAG and controls for DCP VD, FAZ parameters, and the retinal and choriocapillaris flow area (p > 0.05). SCP VD in the whole image and perifovea were significantly lower in POAG patients in stage 2 than stage 0 (p < 0.001). The AUCs of SCP VD in the whole image (0.86) and perifovea (0.84) were significantly higher than the AUCs of all DCP VD (p < 0.05), FAZ parameters (p < 0.001), and retinal (p < 0.001) and choriocapillaris flow areas (p < 0.05). Whole image SCP VD was similar to the AUC of the global retinal nerve fiber layer (RNFL) (AUC = 0.89, p = 0.53) and ganglion cell complex (GCC) thickness (AUC = 0.83, p = 0.42). Conclusions: SCP VD is lower with increasing functional damage in POAG patients. The AUC for SCP VD was similar to RNFL and GCC using clinical diagnosis as the reference standard.

Rates of Choriocapillaris Microvascular Dropout and Macular Structural Changes in Glaucomatous Optic Neuropathy With and Without Myopia

PURPOSE

To evaluate the association between rates of juxtapapillary choriocapillaris microvasculature dropout (MvD) change and rates of ganglion cell inner plexiform layer (GCIPL) loss in primary open-angle glaucoma (POAG) and glaucoma suspect eyes with and without myopia.

DESIGN

Cohort study from clinical trial data.

METHODS

238 eyes from 155 POAG and glaucoma suspect patients were stratified into no-myopia (axial length (AL) ≤ 24 mm; n = 78 eyes), mild myopia (24 mm < AL ≤ 26 mm; n = 114 eyes), and high myopia (AL > 26 mm; n = 46 eyes). Eyes with a minimum of 3 visits and 1.5 years of follow-up with both optical coherence tomography angiography (OCT-A) and OCT macula scans were included. Presence, area, and angular circumference of juxtapapillary MvD were evaluated on en face choroidal images and horizontal B-scans obtained from OCT-A imaging.

RESULTS

Over the mean follow-up of 4.4 years, the mean MvD area rates of change (95% CI) were largest in high and mild myopia group (0.04 [0.03, 0.05] mm2/year in both groups), followed by the no-myopia group (0.03 [0.02, 0.04] mm2/year). The mean MvD angular circumference rates of change (95% CI) were highest in mild myopia group (8.7° [6.9°, 10.5°]/year) followed by the high myopia and no-myopia groups (8.1° [5.3°, 10.9°]/year, and 7.4° [5.3°, 9.6°]/year, respectively). While the mean global GCIPL thinning rates between eyes with MvD at baseline compared to eyes without were similar in all myopia groups, the rates of MvD area change were significantly faster in all myopia groups with baseline MvD (all p ≤ 0.004). Significant faster rates of MvD angular circumference change were found in the mild myopia group with baseline MvD (P < .001) only. In multivariable models, the rates of GCIPL thinning over time were significantly associated with rates of MvD angular circumference change and MvD area change (R2 = 0.33, P < .001 and R2 = 0.32, P = .006, respectively).

CONCLUSIONS

Rates of GCIPL thinning were associated with rates of MvD area and angular circumference change over time in myopic POAG eyes. Utilizing OCT-A to detect MvD may provide an additional tool for monitoring macular structural changes in glaucomatous eyes with myopia.

OCT Optic Nerve Head Morphology in Myopia IV: Neural Canal Scleral Flange Remodeling in Highly Myopic Eyes

PURPOSE

To compare the prevalence, location and magnitude of optic nerve head (ONH) OCT-detected, exposed neural canal (ENC), externally oblique choroidal border tissue (EOCBT) and exposed scleral flange (ESF) regions in 122 highly myopic (Hi-Myo) versus 362 nonhighly myopic healthy (Non-Hi-Myo-Healthy) eyes.

DESIGN

Cross-sectional study.

METHODS

After OCT radial B-scan, ONH imaging, Bruch's membrane opening (BMO), the anterior scleral canal opening (ASCO), and the scleral flange opening (SFO) were manually segmented in each B-scan and projected to BMO reference plane. The direction and magnitude of BMO/ASCO offset and BMO/SFO offset as well as the location and magnitude of ENC, EOCBT and ESF regions, perineural canal (pNC) retinal nerve fiber layer thickness (RNFLT) and pNC choroidal thickness (CT) were calculated within 30° sectors relative to the Foveal-BMO (FoBMO) axis. Hi-ESF eyes were defined to be those with an ESF region ≥100 µms in at least 1 sector.

RESULTS

Hi-Myo eyes more frequently demonstrated Hi-ESF regions (87/122) than Non-Hi-myo-Healthy eyes (73/362) and contained significantly larger ENC, EOCBT, and ESF regions (P < .001) which were greatest in magnitude and prevalence within the inferior-temporal FoBMO sectors where Hi-Myo pNC-RNFLT and pNCCT were thinnest. BMO/ASCO offset and the BMO/SFO offset were both significantly increased (P < .001) in the Hi-Myo eyes, with the latter demonstrating a greater increase.

CONCLUSIONS

ENC region tissue remodeling that includes the scleral flange is enhanced in Hi-Myo compared to Non-Hi-Myo-Healthy eyes. Longitudinal studies are necessary to determine whether the presence of an ENC region influences ONH susceptibility to aging and/or glaucoma.

Myopia: Histology, clinical features, and potential implications for the etiology of axial elongation

Myopic axial elongation is associated with various non-pathological changes. These include a decrease in photoreceptor cell and retinal pigment epithelium (RPE) cell density and retinal layer thickness, mainly in the retro-equatorial to equatorial regions; choroidal and scleral thinning pronounced at the posterior pole and least marked at the ora serrata; and a shift in Bruch's membrane opening (BMO) occurring in moderately myopic eyes and typically in the temporal/inferior direction. The BMO shift leads to an overhang of Bruch's membrane (BM) into the nasal intrapapillary compartment and BM absence in the temporal region (i.e., parapapillary gamma zone), optic disc ovalization due to shortening of the ophthalmoscopically visible horizontal disc diameter, fovea-optic disc distance elongation, reduction in angle kappa, and straightening/stretching of the papillomacular retinal blood vessels and retinal nerve fibers. Highly myopic eyes additionally show an enlargement of all layers of the optic nerve canal, elongation and thinning of the lamina cribrosa, peripapillary scleral flange (i.e., parapapillary delta zone) and peripapillary choroidal border tissue, and development of circular parapapillary beta, gamma, and delta zone. Pathological features of high myopia include development of macular linear RPE defects (lacquer cracks), which widen to round RPE defects (patchy atrophies) with central BM defects, macular neovascularization, myopic macular retinoschisis, and glaucomatous/glaucoma-like and non-glaucomatous optic neuropathy. BM thickness is unrelated to axial length. Including the change in eye shape from a sphere in emmetropia to a prolate (rotational) ellipsoid in myopia, the features may be explained by a primary BM enlargement in the retro-equatorial/equatorial region leading to axial elongation.

Value of optical coherence tomography measurement of macular thickness and optic disc parameters for glaucoma screening in patients with high myopia

BACKGROUND

The basic method of glaucoma diagnosis is visual field examination, however, in patients with high myopia, the diagnosis of glaucoma is difficult.

AIM

To explore the value of optical coherence tomography (OCT) for measuring optic disc parameters and macular thickness as a screening tool for glaucoma in patients with high myopia.

METHODS

Visual values (contrast sensitivity, color vision, and best-corrected visual acuity) in three groups, patients with high myopia in Group A, patients with high myopia and glaucoma in Group B, and patients with high myopia suspicious for glaucoma in Group C, were compared. Optic disc parameters, retinal nerve fiber layer (RNFL) thickness, and ganglion cell layer (GCC) thickness were measured using OCT technology and used to compare the peri-optic disc vascular density of the patients and generate receiver operator characteristic (ROC) test performance curves of the RNFL and GCC for high myopia and glaucoma.

RESULTS

Of a total of 98 patients admitted to our hospital from May 2018 to March 2022, totaling 196 eyes in the study, 30 patients with 60 eyes were included in Group A, 33 patients with 66 eyes were included in Group B, and 35 patients with 70 eyes were included in Group C. Data were processed for Groups A and B to analyze the efficacy of RNFL and GCC measures in distinguishing high myopia from high myopia with glaucoma. The area under the ROC curve was greater than 0.7, indicating an acceptable diagnostic value.

CONCLUSION

The value of OCT measurement of RNFL and GCC thickness in diagnosing glaucoma in patients with high myopia and suspected glaucoma is worthy of development for clinical use.