Optical Coherence Tomography Can Be Used to Assess Glaucomatous Optic Nerve Damage in Most Eyes With High Myopia

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.

The challenges of diagnosing glaucoma in myopic cases and the important role of Bruch's membrane opening-minimum rim width in the diagnosis of myopic glaucoma

BACKGROUND

Glaucoma is a progressive neurodegenerative disease that can lead to blindness; furthermore, axial myopia is associated with retinal and optic nerve changes that mimic glaucoma. Diagnosing glaucoma in myopic eyes is challenging due to anatomical variations, emphasizing the need for precise OCT-based evaluations.

OBJECTIVE

To evaluate the retinal nerve fiber layer (RNFL) thickness and Bruch's Membrane Opening-Minimum Rim Width (BMO-MRW) parameters in myopic patients with and without glaucoma by using Spectralis® optical coherence tomography (OCT), in order to reveal the relationship between axial length (AL) and OCT parameters and also to determine the OCT parameters that should be considered when diagnosing glaucoma in myopic cases.

MATERIAL AND METHOD

This prospective and cross-sectional study included 95 eyes from 95 cases. There were a total of 54 patients over 40 years of age without any systemic disease or glaucoma, and 41 patients without any systemic disease but with mild or moderate glaucoma, according to the Hodapp staging system. Optical biometry using the Lenstar® 900 and Heidelberg Engineering Spectralis® OCT Glaucoma Module Premium Edition (GMPE) with an anatomic positioning system (APS) were performed on all patients, along with a full ophthalmological examination. The cases were divided into subgroups according to the AL results of optical biometry as short (<24 mm) and long (≥24 mm). The measurement results were recorded and compared statistically.

RESULTS

A total of 54 healthy subjects consisting of 27 with short AL and 27 with long AL were included. In the glaucoma group, 20 out of 41 subjects had short AL, while 21 had long AL. Using measurements in GMPE mode with APS, no statistically significant difference was found between the eyes with the short and long AL in the healthy group, both in terms of global RNFL thickness and BMO-MRW analyses. In the glaucoma group, there was no statistically significant difference between eyes with short and long AL in terms of RNFL and MRW analyses. In the myopic group, the highest AUC value of the RNFL measurements in different circular scans of the GMPE module was found in the inferotemporal area. Using the GMPE software with the APS to measure RNFL thickness, in particular in the inferotemporal quadrant, together with the BMO-MRW, really helped to make a definite diagnosis of glaucoma in myopic patients.

CONCLUSION

In conclusion, utilizing GMPE with APS in the diagnosis of glaucoma provides accurate outcomes in myopic cases. The RNFL thickness and BMO-MRW values of the inferotemporal quadrant are particularly valuable in diagnosing glaucoma in myopic patients.

Detection of retinal nerve fiber layer in patients with high myopia complicated with glaucoma by optical coherence tomography

OBJECTIVE

To detect the changes in the thickness of the Retinal Nerve Fiber Layer (RNFL) in patients with High Myopia (HM) complicated with glaucoma through Optical Coherence Tomography (OCT).

METHODS

80 patients (160 eyes) with HM complicated with glaucoma treated from March 2018 to March 2020 were enrolled as the experimental group, and 60 healthy volunteers (120 eyes) undergoing physical examination in the same period were selected as the control group. OCT measured their RNFL thicknesses.

RESULTS

Compared with that in the control group, the nasal, supratemporal, subnasal, supranasal, and infratemporal RNFL thickness and overall mean RNFL thickness in the experimental group was significantly decreased, while the temporal RNFL thickness was significantly increased in the experimental group (P < 0.05). According to the diopter, patients in the experimental group were assigned into group A (n = 25, 50 eyes, diopter range: ≥ -6.00 D and ≤ -8.00 D), group B (n = 30, 60 eyes, diopter range: > -8.00 D and ≤ -10.00 D) and group C (n = 25, 50 eyes, diopter range: > -10.00 D). The nasal, supratemporal, subnasal, supranasal, and infratemporal RNFL thickness and overall mean RNFL thickness in group A were significantly greater than those in groups B and C (P < 0.05). Spearman correlation analysis revealed that the absolute value of diopter was negatively correlated with the nasal, supratemporal, subnasal, supranasal, and infratemporal RNFL thickness and overall mean RNFL thickness (P < 0.05), and positively correlated with the thickness of temporal RNFL (P < 0.05).

CONCLUSION

In patients with HM complicated with glaucoma, RNFL is thinner in all quadrants except for temporal RNFL.

Comprehensive assessment of glaucoma in patients with high myopia: a systematic review and meta-analysis with a discussion of structural and functional imaging modalities

PURPOSE

The interplay between myopia and glaucoma has gained attention, with escalating myopia demonstrating a significant association with increased POAG rates, particularly in patients with severe myopia. This systematic review aimed to comprehensively analyze the relationship between myopia and glaucoma, focusing on the structural and functional implications, risk factors, and assessment modalities. Optical coherence tomography (OCT) played a crucial role in this study, particularly in highly myopic populations.

METHODS

This study's rigor is underscored by using the PRISMA guidelines, which ensured a meticulous search strategy was employed across multiple databases from 2012 to 2024. The inclusion criteria included individuals aged 18 years or older with high myopia, defined as a spherical equivalent of less than -6.0 diopters or an axial length > 26.0 mm, diagnosed with chronic glaucoma. Various study designs were incorporated, including randomized controlled trials, prospective cohort studies, and observational studies. Quality assessment was performed using the Jadad Scale, and statistical analyses were performed to summarize the study characteristics and outcomes.

RESULTS

Of the 350 initial articles, 15 met the inclusion criteria. OCT assessments revealed structural changes such as thinning of the retinal nerve fiber layer preceding functional losses. Meta-analyses demonstrated a heightened risk of POAG with increasing myopia severity, showing a significant nonlinear relationship. This meta-analysis of six studies involving 3040 patients revealed a relationship between myopia and glaucoma (OR = 12.0, 95% CI 10.1-4.7, P < 0.00001).

CONCLUSION

This comprehensive analysis consolidates the evidence of the relationship between myopia and glaucoma, emphasizing the pivotal role of OCT and other imaging modalities in early detection and monitoring.

Optic neuropathy in high myopia: Glaucoma or high myopia or both?

Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much attention. Evidence has shown that high myopia is related to the development of glaucomatous or glaucoma-like optic neuropathy, and that both have many common features. These similarities often pose a diagnostic challenge that will affect the future management of glaucoma suspects in high myopia. In this review, we summarize similarities and differences in optic neuropathy arising from non-pathologic high myopia and glaucoma by considering their respective structural and functional characteristics on fundus photography, optical coherence tomography scanning, and visual field tests. These features may also help to distinguish the underlying mechanisms of the optic neuropathies and to determine management strategies for patients with high myopia and glaucoma.

Glaucoma Detection Using Optical Coherence Tomography: Reviewing the Pitfalls of Comparison to Normative Data

PRCIS

Optical coherence tomography is essential in managing glaucoma. This review describes various artifacts that originate from using a normative database to compare the individual's scans. This is a review paper regarding artifacts in optical coherence tomography imaging for glaucoma arising from using a normative database as a reference for healthy retinal nerve fiber layer and ganglion cell layer.

Addressing Glaucoma in Myopic Eyes: Diagnostic and Surgical Challenges

Epidemiological and genetic studies provide strong evidence supporting an association between myopia and glaucoma. The accurate detection of glaucoma in myopic eyes, especially those with high myopia, remains clinically challenging due to characteristic morphologic features of the myopic optic nerve in addition to limitations of current optic nerve imaging modalities. Distinguishing glaucoma from myopia is further complicated by overlapping perimetric findings. Therefore, longitudinal follow-up is essential to differentiate progressive structural and functional abnormalities indicative of glaucoma from defects that may result from myopia alone. Highly myopic eyes are at increased risk of complications from traditional incisional glaucoma surgery and may benefit from newer microinvasive glaucoma surgeries in select cases.

Ab-externo canaloplasty with and without suture in highly myopic eyes

PURPOSE

To evaluate the effectiveness of ab-externo canaloplasty using the iTrack canaloplasty microcatheter (Nova Eye Inc, Fremont, California), with or without suture, in glaucoma patients with high myopia.

METHODS

This was a prospective, single-center, single-surgeon, observational study comparing the outcomes of ab-externo canaloplasty performed with a tensioning suture (suture group) and without a tensioning suture (no-suture group) in mild to severe glaucoma patients with high myopia. Twenty-three eyes received canaloplasty as a standalone procedure, 5 in combination with phacoemulsification. Primary efficacy endpoints included intraocular pressure (IOP) and the number of glaucoma medications. Safety was assessed based on reported complications and adverse events.

RESULTS

Twenty-nine eyes of 29 patients with a mean age of 61.2 ± 12.3 years; 19 eyes in the no-suture group and 10 eyes in the suture group. All eyes demonstrated a significant reduction in IOP 24 months postoperatively, from 21.9 ± 7.22 to 15.4 ± 4.86 mmHg in the suture group and from 23.8 ± 7.58 to 19.7 ± 3.68 mmHg in the no-suture group. The mean number of anti-glaucoma medications reduced from 3.1 ± 0.6 to 0.4 ± 0.7 in the suture group and 3.3 ± 0.9 to and 0.2 ± 0.6 in the no-suture group at 24 months. IOP was not significantly different at baseline between the 2 groups, but it was statistically different at 12 and 24 months. There was no statistically significant difference in the number of medications between the groups at baseline, 12 and 24 months. No serious complications were reported.

CONCLUSION

Ab-externo canaloplasty performed either with or without a tensioning suture demonstrated good effectiveness in highly myopic eyes with a significant reduction in IOP and number of anti-glaucoma medications. The suture group achieved a lower postoperative IOP. However, the no-suture modification provides a similar reduction in medications with reduced tissue handling.

The Prevalence of Optical Coherence Tomography Artifacts in High Myopia and its Influence on Glaucoma Diagnosis

PRCIS

Optical coherence tomography (OCT) artifacts occur much more frequently in highly myopic eyes compared with non-highly myopic eyes. A longer axial length is predictive of having OCT artifacts.

PURPOSE

To investigate the types and prevalence of artifacts on OCT scans in patients with and without high myopia.

MATERIALS AND METHODS

Patients were divided into 4 groups based on whether they had glaucoma and/or high myopia. All peripapillary retinal nerve fiber layer (RNFL) scan images were individually inspected for the presence of artifacts.

RESULTS

Two hundred twenty-six patients were enrolled. The prevalence of OCT artifacts was 18.6% in non-high myopes and 51.9% in high myopes ( P <0.001). Outer RNFL border misidentification was the most common type of artifact for non-high myopes, whereas retinal pathology-related artifact was the most common in high myopes. Univariable regression analysis showed that a longer axial length [odds ratio (OR) 1.815, P <0.001], a higher pattern standard deviation (OR 1.194, P <0.001), and thinner RNFL (OR 0.947, P <0.001) were predictive factors for the presence of OCT artifacts. The diagnostic capability of global RNFL thickness before and after manual correction of segmentation errors did not differ for both non-high myopes [area under the receiver operating curve 0.915-0.913 ( P =0.955)] and high myopes [area under the receiver operating curve 0.906-0.917 ( P =0.806)].

CONCLUSION

The prevalence of OCT artifacts was the highest in patients with both high myopia and glaucoma. The most common type of OCT artifact is different for non-high myopes and high myopes. Physicians need to be aware of a higher likelihood of OCT artifacts, particularly in those with a longer axial length, worse visual field, and thinner RNFL thickness.

Glaucoma and Myopia: Diagnostic Challenges

The rising global prevalence of myopia is a growing concern for clinicians, as it predisposes patients to severe ocular pathologies including glaucoma. High myopia can be associated with clinical features that resemble glaucomatous damage, which make an accurate glaucoma diagnosis challenging, particularly among patients with normal intraocular pressures. These patients may also present with established visual field defects which can mimic glaucoma, and standard imaging technology is less useful in disease detection and monitoring due to the lack of normative data for these anatomically unique eyes. Progression over time remains the most critical factor in facilitating the detection of early glaucomatous changes, and thus careful longitudinal follow-up of high-risk myopic patients is the most important aspect of management. Here, we review our current understanding of the complex relationship between myopia and glaucoma, and the diagnostic challenges and limitations of current testing protocols including visual field, intraocular pressure, and imaging. Furthermore, we discuss the clinical findings of two highly myopic patients with suspected glaucoma.

Correction of refractive distortion in whole-eye optical coherence tomography imaging of the mouse eye

Optical coherence tomography (OCT) is an imaging modality that acquires high-resolution cross-sectional images of living tissues and it has become the standard in ophthalmological diagnoses. However, most quantitative morphological measurements are based on the raw OCT images which are distorted by several mechanisms such as the refraction of probe light in the sample and the scan geometries and thus the analysis of the raw OCT images inevitably induced calculation errors. In this paper, based on Fermat's principle and the concept of inverse light tracing, image distortions due to refraction occurred at tissue boundaries in the whole-eye OCT imaging of mouse by telecentric scanning were corrected. Specially, the mathematical correction models were deducted for each interface, and the high-precision whole-eye image was recovered segment by segment. We conducted phantom and in vivo experiments on mouse and human eyes to verify the distortion correction algorithm, and several parameters of the radius of curvature, thickness of tissues and error, were calculated to quantitatively evaluate the images. Experimental results demonstrated that the method can provide accurate and reliable measurements of whole-eye parameters and thus be a valuable tool for the research and clinical diagnosis.

A Myopic Normative Database for Retinal Nerve Fiber Layer Thickness using Optical Coherence Tomography

PRCIS

The purpose of this study was to determine changes in OCT color codes after applying a myopic normative database. The diagnostic performance of the retinal nerve fiber layer analysis improved with the use of this database.

PURPOSE

To evaluate the pRNFL color codes based on a newly generated myopic normative database in comparison to the built-in normative database.

METHODS

A total of 371 subjects were included in this validation study in an attempt to generate a myopic normative database. Eighty myopic glaucomatous and 80 myopic healthy eyes were evaluated to determine the diagnostic performance of this database. The distribution of the color codes was investigated among the groups with reference to the built-in and myopic normative databases, and the two databases were compared in terms of abnormal color code frequency. The diagnostic performance of the myopic database was presented with sensitivity, specificity and area under the receiver operating characteristics curve (AUROC) values.

RESULTS

The agreement between the databases decreased with increasing myopia degree. The distribution of the color codes of the built-in software significantly differed among the study groups in all sectors (P=0.009 for the temporal sector and P<0.001 for the remaining sectors). When the myopic database was used, there were no longer significant differences among the groups for the temporosuperior, temporoinferior, temporal and nasal sectors (P=0.561, 0.299, 0.201, and 0.089 respectively). After applying the myopic normative database, the specificity of the pRNFL color codes increased from 70.1% to 90.2%, and the AUROC value from 0.851 to 0.945.

CONCLUSIONS

The use of a myopic normative database for pRNFL using SD-OCT significantly decreased differences among myopia severity groups, and may help to more reliably assess glaucoma in myopic eyes.

Advances in OCT Imaging in Myopia and Pathologic Myopia

Advances in imaging with optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) technology, including the development of swept source OCT/OCTA, widefield or ultra-widefield systems, have greatly improved the understanding, diagnosis, and treatment of myopia and myopia-related complications. Anterior segment OCT is useful for imaging the anterior segment of myopes, providing the basis for implantable collamer lens optimization, or detecting intraocular lens decentration in high myopic patients. OCT has enhanced imaging of vitreous properties, and measurement of choroidal thickness in myopic eyes. Widefield OCT systems have greatly improved the visualization of peripheral retinal lesions and have enabled the evaluation of wide staphyloma and ocular curvature. Based on OCT imaging, a new classification system and guidelines for the management of myopic traction maculopathy have been proposed; different dome-shaped macula morphologies have been described; and myopia-related abnormalities in the optic nerve and peripapillary region have been demonstrated. OCTA can quantitatively evaluate the retinal microvasculature and choriocapillaris, which is useful for the early detection of myopic choroidal neovascularization and the evaluation of anti-vascular endothelial growth factor therapy in these patients. In addition, the application of artificial intelligence in OCT/OCTA imaging in myopia has achieved promising results.

The OCT RNFL Probability Map and Artifacts Resembling Glaucomatous Damage

Purpose

The purpose of this study was to improve the diagnostic ability of the optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) probability (p-) map by understanding the frequency and pattern of artifacts seen on the p-maps of healthy control (HC) eyes resembling glaucomatous damage.

Methods

RNFL p-maps were generated from wide-field OCT cube scans of 2 groups of HC eyes, 200 from a commercial normative group (HC-norm) and 54 from a prospective study group, as well as from 62 patient eyes, which included 32 with early glaucoma (EG). These 32 EG eyes had 24-2 mean deviation (MD) better than -6 dB and perimetric glaucoma as defined by 24-2 and 10-2 criteria. For the HC groups, "glaucoma-like" arcuates were defined as any red region near the temporal half of the disc.

Results

Seven percent of the 200 HC-norm and 11% of the 54 HC RNFL p-maps satisfied the definition of "glaucoma-like," as did all the patients' p-maps. The HC p-maps showed two general patterns of abnormal regions, "arcuate" and "temporal quadrant," and these patterns resembled those seen on some of the RNFL p-maps of the EG eyes. A "vertical midline" rule, which required the abnormal region to cross the vertical midline through the fovea, had a specificity of >99%, and a sensitivity of 75% for EG and 93% for moderate to advanced eyes.

Conclusions

Glaucoma-like artifacts on RNFL p-maps are relatively common and can masquerade as arcuate and/or widespread/temporal damage.

Translational Relevance

A vertical midline rule had excellent specificity. However, other OCT information is necessary to obtain high sensitivity, especially in eyes with early glaucoma.

Are There Static-Structural Biomarkers for Glaucoma with OCT?

Glaucomas lead to uniform, specific and slowly developing atrophy of the optic nerve with progressing visual field defects in late stages. Early diagnosis is challenging, but necessary as optic nerve damage is irreparable. Biomarkers with structural optical coherence tomography (OCT) flag optic atrophy but do not prove to be specific in the differential diagnosis to other forms of optic atrophy. Combination of OCT parameters and their correlation to other variables facilitate glaucoma diagnosis. Use of artificial intelligence (AI) in structural OCT images may prove to be superior and as biomarker more specific to thickness measurements of neuronal tissues alone.

Detecting glaucoma with only OCT: Implications for the clinic, research, screening, and AI development

A method for detecting glaucoma based only on optical coherence tomography (OCT) is of potential value for routine clinical decisions, for inclusion criteria for research studies and trials, for large-scale clinical screening, as well as for the development of artificial intelligence (AI) decision models. Recent work suggests that the OCT probability (p-) maps, also known as deviation maps, can play a key role in an OCT-based method. However, artifacts seen on the p-maps of healthy control eyes can resemble patterns of damage due to glaucoma. We document in section 2 that these glaucoma-like artifacts are relatively common and are probably due to normal anatomical variations in healthy eyes. We also introduce a simple anatomical artifact model based upon known anatomical variations to help distinguish these artifacts from actual glaucomatous damage. In section 3, we apply this model to an OCT-based method for detecting glaucoma that starts with an examination of the retinal nerve fiber layer (RNFL) p-map. While this method requires a judgment by the clinician, sections 4 and 5 describe automated methods that do not. In section 4, the simple model helps explain the relatively poor performance of commonly employed summary statistics, including circumpapillary RNFL thickness. In section 5, the model helps account for the success of an AI deep learning model, which in turn validates our focus on the RNFL p-map. Finally, in section 6 we consider the implications of OCT-based methods for the clinic, research, screening, and the development of AI models.