Relationship Between Anterior Lamina Cribrosa Surface Tilt and Glaucoma Development in Myopic Eyes:

Evaluating glaucoma in myopic eyes: Challenges and opportunities

The increasing global prevalence of myopia presents a significant public health concern, and growing evidence has demonstrated that myopia is a major risk factor for the development of open-angle glaucoma. Therefore, timely detection and management of glaucoma in myopic patients are crucial; however, identifying the structural alterations of glaucoma in the optic nerve head (ONH) and retinal tissues of myopic eyes using standard diagnostic tools such as fundus photography, optical coherence tomography (OCT), and OCT angiography (OCTA) presents challenges. Additionally, myopia-related perimetric defects can be confounded with glaucoma-related defects. We comprehensively examine the challenges encountered in evaluating glaucoma in myopic eyes through various diagnostic tools, including fundus photography, OCT of the ONH, retinal nerve fiber layer, and macular ganglion cell layer, OCTA, and perimetry. We also explore potential opportunities to address these challenges, providing insights for clinicians to effectively manage myopic glaucoma patients in clinical practice.

Measurement of the Tilt Angle of the Optic Disc Using Spectral-Domain Optical Coherence Tomography and Related Factors in Myopia

Purpose

This study presents a novel, three-dimensional method for measuring the tilt angle of the tilted optic disc (TOD) using spectral-domain optical coherence tomography (SD-OCT) and investigates the correlation between ocular-related parameters and TOD.

Methods

We included the right eyes of 243 healthy young individuals, categorized by axial length. We measured the ovality index (OI) and dihedral angle (DA) using SD-OCT infrared ray fundus photographs and high-resolution cross-sectional images of the optic disc, respectively. The relationships between OI, DA, and ocular-related parameters were analyzed.

Results

Eyes in the longer axial length group exhibited a lower OI and a higher DA, along with thinner nasal and inferonasal circumpapillary retinal nerve fiber layer (cpRNFL) and thicker temporal and superotemporal cpRNFL. There was a significant relationship between DA and cpRNFL thickness. The new method utilizing DA to measure the tilt angle of TOD demonstrated high repeatability.

Conclusions

We propose a novel, three-dimensional, and quantitative method for evaluating the tilt degree of TOD. A higher degree of myopia indicated a greater tilt angle of the TOD, and a greater TOD suggested additional changes in cpRNFL thickness. These findings should be considered when interpreting increased susceptibility and early assessment of glaucoma in myopia.

Translational Relevance

DA could serve as a superior indicator for describing TOD morphology during eyeball elongation and evaluating its impact on related parameters of the optic disc and peripapillary structures in the myopic population.

Optic Nerve Head Curvature Flattening Is Associated with Central Visual Field Scotoma

This study aimed to develop a new index, the average curvature ratio (ACR), to represent the optic nerve head (ONH) tilting and investigate its clinical relevance. Myopic eyes were included and divided into two subgroups: flat ONH (ACR < 1.0) and convex ONH (ACR ≥ 1.0). The occurrences of central and peripheral visual field (VF) defects were compared between the two groups. A total of 375 myopic eyes were recruited, and 231 and 144 eyes were included in the flat and convex ONH groups, respectively. Central scotoma occurred more frequently in the flat ONH group. According to the Patella-Anderson criteria, the number of eyes with central scotoma was 103 (44.6%) in the flat and 44 (30.6%) in the convex ONH groups (p = 0.009). According to Kook's criteria, the number of eyes with central scotoma was 122 (52.8%) in the flat and 50 (34.7%) in the convex ONH groups (p < 0.001). Peripheral scotoma was not significantly different between the groups. In the correlation analysis, the ACR was positively correlated with spherical equivalence, but not with axial length or central corneal thickness. The ACR reflects the degree of the ONH tilt and is a good index for estimating central VF damage in myopic eyes.

Deep Optic Nerve Head Morphology in Tilted Disc Syndrome and Its Clinical Implication on Visual Damage

Purpose

To study deep optic nerve head (ONH) morphology in tilted disc syndrome (TDS) and identify factors associated with retinal nerve fiber layer (RNFL) defect.

Methods

In patients with TDS, we evaluated the optic disc shape using the Bruch's membrane opening (BMO)-anterior scleral canal opening (ASCO) offset and measured the border tissue (BT) length, depth, and angle in the direction of the tilt, using radial ONH optical coherence tomography (OCT). We compared the parameters between the TDS groups with and without RNFL defects.

Results

Twenty-one eyes had no glaucomatous RNFL defect, and 38 eyes had a glaucomatous RNFL defect. The group with RNFL defects had a higher baseline IOP, larger tilt axis of BMO-ASCO optic disc margin (76.4° ± 14.5° vs. 87.9° ± 15.4°, P = 0.012), larger BMO-lamina cribrosa insertion (LCI) angle (25.6° ± 9.3° vs. 43.6° ± 15.2°, P < 0.001), and more lamina cribrosa (LC) defects (4.3% vs. 30.6%, P = 0.028) than without RNFL defects. The tilt axis and BMO-LCI angle were significant factors after adjusting for baseline IOP and LC defect. The BMO-LCI angle had excellent diagnostic power for glaucomatous RNFL defect in TDS, similar to the visual field mean deviation.

Conclusions

OCT-based large deep ONH BT angle and tilt axis were factors associated with the presence of RNFL defects in TDS. The results suggest a mechanism of RNFL defect associated with structural ONH deformation. Further investigations are warranted to understand the role of ONH structures in a general population with and without optic disc tilt.

Myopic tilted disc: Mechanism, clinical significance, and public health implication

Myopic tilted disc is a common structural change of myopic eyes. With advancing ocular imaging technology, the associated structural changes of the eye, particularly the optic nerve head, have been extensively studied. These structural changes may increase patients' susceptibility to axonal damage and the risk of developing serious optic neuropathies including glaucoma. They also lead to diagnostic difficulties of disease suspects and treatment dilemmas of patients, which implicate clinical practice and subsequently the health care system. In the context of the mounting prevalence of myopia worldwide and its implications to irreversible visual impairment and blindness, it is essential to gain a thorough understanding of the structural changes of myopia. Myopic tilted disc has been extensively investigated by different study groups. However, generalizing the knowledge could be difficult because of the variable definitions of myopic tilted disc utilized in these studies and the complexities of the changes. The current review aimed to clarify the concepts and discuss various aspects of myopic tilted disc, including the definitions, association with other myopia-related changes, mechanism of tilted disc development, structural and functional changes, and clinical implications.

Longitudinal Changes of Optic Nerve Head and Peripapillary Structure during Childhood Myopia Progression on OCT: Boramae Myopia Cohort Study Report 1

PURPOSE

To delineate longitudinal changes in the optic nerve head (ONH) and peripapillary structure during myopia progression in childhood using spectral-domain (SD) OCT and to explore the factors associated with myopic ONH and peripapillary changes.

DESIGN

Prospective cohort study.

PARTICIPANTS

Twenty-three healthy children with myopia (46 eyes).

METHODS

The participants underwent fundus photography, SD OCT, and axial length (AXL) measurements every 6 months for 2 years. Based on the morphologic changes of the ONH and β-zone parapapillary atrophy (PPA), eyes were classified as group A (ONH unchanged without β-zone PPA; 11 eyes), group B (ONH changed without β-zone PPA at baseline; 10 eyes), group C (ONH changed with β-zone PPA at baseline; 15 eyes), and group D (ONH unchanged with β-zone PPA; 10 eyes). The configuration of the border tissue (BT) at the temporal margin of the ONH was assessed, and the ONH parameters, including Bruch's membrane opening distance (BMOD), border length (BL), and BT angle (BTA), were measured on horizontal SD OCT scans.

MAIN OUTCOME MEASURES

Changes in ONH parameters and associated factors.

RESULTS

Group B showed the greatest AXL increase per year (group B > group C > group A = group D; P < 0.001). During the follow-up periods, the BT configuration initially was changed from internally oblique to externally oblique (group B) and was stretched, resulting in optic disc ovality and γ-zone PPA development (group C). In group C, BL was increased significantly nasally and BTA was decreased significantly, whereas BMOD remained stable (P < 0.001, P < 0.001, and P = 0.100, respectively). In the multivariate analysis using the generalized linear mixed-effect model, the changes of BL and BTA were associated with axial elongation (P = 0.028 and P = 0.010, respectively).

CONCLUSIONS

Development of myopic optic disc and γ-zone PPA during myopia progression was delineated using SD OCT images. During the ONH and peripapillary changes, the BL was increased nasally and the BTA was decreased, whereas the BMOD remained relatively stable. The association of axial elongation with ONH and peripapillary tissue changes may facilitate understanding of the relationship between myopia and glaucoma.