Lamina cribrosa position and Bruch's membrane opening differences between anterior ischemic optic neuropathy and open-angle glaucoma

Vitreopapillary Findings in Nonarteritic Ischemic Optic Neuropathy versus Healthy Eyes: A Clinical and OCT Comparison

PURPOSE

To study the vitreopapillary interface in nonarteritic ischemic optic neuropathy (NAION) for features that may predispose to optic nerve perfusion defects.

DESIGN

Case-control study.

PARTICIPANTS AND CONTROLS

Patients with NAION (study group) were compared with healthy non-NAION patients with crowded discs (control group I) and noncrowded optic discs (control group II).

METHODS

The vitreopapillary interface was studied in 32 eyes with NAION using high-resolution OCT scans. Results were compared with 2 control groups consisting of age, sex, and refraction-matched non-NAION individuals with crowded optic discs (control group I: 31 eyes) and noncrowded optic discs (control group II: 32 eyes).

MAIN OUTCOME MEASURES

The incidence of total posterior vitreous detachment (PVD), vitreopapillary and vitreovascular attachments, and epipapillary membranes.

RESULTS

The rate of PVD over the macula was similar between groups (NAION: 62.5%, control I: 61.3%, and control II: 65.6%, P = 0.93), whereas the posterior hyaloid remained attached to the crowded discs at a significantly higher rate (NAION: 81.2%, control I: 83.9% and control II: 43.7%, P = 0.0005). A higher rate of focal vitreopapillary attachments on crowded discs than on noncrowded discs was noted (NAION: 72.2%, crowded control I: 58.7%, and noncrowded control II: 19.1%, P = 0.007). Vitreovascular attachments (NAION: 68.8%, crowded control I: 3.2% vs. noncrowded control II: 6.3%, P = 0.00001) and dense epipapillary membranes were observed in NAION eyes.

CONCLUSIONS

Crowded discs may have stronger vitreopapillary attachments. A close relationship of these attachments with optic nerve vessels may lead to the transmission of strong tractional forces by a syneretic vitreous gel, especially after macular PVD. This transduced mechanical force may contort the vessel wall and disrupt the blood flow in NAION.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Evaluation of the lamina cribrosa after topical latanoprost therapy in primary open-angle glaucoma or ocular hypertension

PURPOSE

To investigate that the changes of lamina cribrosa (LC) thickness and depth after latanoprost therapy in primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients.

METHODS

In this single-center prospective cross-sectional study, 35 eyes from 35 patients with POAG or OHT (study group) and 26 age- and gender- matched healthy individuals (control group) were included. All participants were examined by spectral domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) mode for LC thickness and depth measurements at the first visit before latanoprost therapy and at visits after 1 (second visit) and 3 (third visit) months of latanoprost therapy.

RESULTS

The mean LC thickness in both horizontal and vertical scans of the study group were thinner than the control group (p < 0.001, for both). During latanoprost therapy in the study group, the LC thickness values in horizontal scans significantly differed over the three visits, gradually increased (p < 0.05). There was significantly decrease in LC depth in horizontal scans between the first and third visits, and the second and third visits (p = 0.003 and p = 0.008, respectively). The gradual decrease in LC depth in vertical scans was observed at all visits, but the statistically significant difference was between the first and third visits only (p = 0.048).

CONCLUSION

POAG/OHT patients showed more LC thinning compared with healthy individuals. The significant increase in LC thickness and the significant decrease in LC depth were detected after IOP reduction therapy with latanoprost in ocular hypertensive/ glaucomatous eyes.

Optical coherence tomography and optical coherence tomography — angiography used in endocrine ophthalmopathy

The literature review presents the results of optical coherence tomography and optical coherence tomography — angiography used for Graves’ orbitopathy. The data on the thickness of the inner layers of the retina, microcirculation in the peripapillary and macular regions, parameters of the choroid, lamina cribrosa and extraocular muscles were analyzed as possible diagnostic criteria of the condition.

Optical coherence tomography angiography (OCT angiography) in anterior ischemic optic neuropathy (AION): A systematic review and meta-analysis

PURPOSE

To summarize the evidence available on optical coherence tomography angiography (OCTA) in patients with anterior ischemic optic neuropathy (AION).

METHODS

Systematic searches were conducted on PubMed, Embase, Web of Science, Scopus, Cochrane, and Google Scholar Databases. The quality assessment of the included studies was performed using Newcastle -Ottawa Scale. The data were extracted to an Excel sheet. Vessel density (VD) data were pooled by random effects model, presented as pooled percentage change (PPC), and weighted mean differences (WMD). Additional subgroup analysis was also conducted.

RESULTS

In initial searches in online databases, we found 3535 citations, and after screening and checking the titles and abstracts, 26 articles were ultimately eligible for our meta-analysis. The overall PPC of Intra-optic-disc (IOD) VD (-10.73%; p = 0.017, I² = 0.0%; p = 0.898) was lower than that of radial peripapillary (RP) VD (-17.57%; p < 0.001, I² = 44.3%; p = 0.002). The overall PPC of peripapillary choroid VD (-6.99%; p < 0.001, I² = 0.0%; p = 0.766) was significant, but noticeably lower than the pooled percentage change of RPVD and IOD VD. The WMD of RPVD was significant when non-affected fellow eyes were compared to the healthy subjects' eyes (-36.26; p < 0.001, I² = 0.0%; p = 0.706).

CONCLUSIONS

The central retinal artery and its branches might be the main vessels which are affected in AION. The superficial retina was more affected than choroid layer in AION. Also, radial peripapillary retinal nerve fibre layer was more affected than the IOD area. OCTA might be a suitable tool for prediction of AION in susceptible eyes.

Optical coherence tomography evaluation of retinal nerve fiber layer thickness in non-arteritic anterior ischemic optic neuropathy and primary open angle glaucoma: a systematic review and Meta-analysis

AIM

To assess the differences in average and sectoral peripapillary retinal nerve fiber layer (pRNFL) thickness using spectral domain optical coherence tomography (SD-OCT) in patients with non-arteritic anterior ischemic neuropathy (NAION) compared with those with primary open angle glaucoma (POAG).

METHODS

A comprehensive literature search of the PubMed, Cochrane Library, and Embase databases were performed prior to October, 2021. Studies that compared the pRNFL thickness in NAION eyes with that in POAG eyes with matched mean deviation of the visual fields were included. The weighted mean difference (WMD) with 95% confidence interval (CI) was used to pool continuous outcomes.

RESULTS

Ten cross-sectional studies (11 datasets) comprising a total of 625 eyes (278 NAION eyes, 347 POAG eyes) were included in the qualitative and quantitative analyses. The pooled results demonstrated that the superior pRNFL was significantly thinner in NAION eyes than in POAG eyes (WMD=-6.40, 95%CI: -12.22 to -0.58, P=0.031), whereas the inferior pRNFL was significant thinner in POAG eyes than in NAION eyes (WMD=11.10, 95%CI: 7.06 to 15.14, P≤0.001). No difference was noted concerning the average, nasal, and temporal pRNFL thickness (average: WMD=1.45, 95%CI: -0.75 to 3.66, P=0.196; nasal: WMD=-2.12, 95%CI: -4.43 to 0.19, P=0.072; temporal: WMD=-1.24, 95%CI: -3.96 to 1.47, P=0.370).

CONCLUSION

SD-OCT based evaluation of inferior and superior pRNFL thickness can be potentially utilized to differentiate NAION from POAG, and help to understand the different pathophysiological mechanisms between these two diseases. Further longitudinal studies and studies using eight-quadrant or clock-hour classification method are required to validate the obtained findings.

Optical Coherence Tomography Imaging of the Lamina Cribrosa: Structural Biomarkers in Nonglaucomatous Diseases

The lamina cribrosa (LC) is an active structure that responds to the strain by changing its morphology. Abnormal changes in LC morphology are usually associated with, and indicative of, certain pathologies such as glaucoma, intraocular hypertension, and myopia. Recent developments in optical coherence tomography (OCT) have enabled detailed in vivo studies about the architectural characteristics of the LC. Structural characteristics of the LC have been widely explored in glaucoma management. However, information about which LC biomarkers could be useful for the diagnosis, and follow-up, of other diseases besides glaucoma is scarce. Hence, this literature review aims to summarize the role of the LC in nonophthalmic and ophthalmic diseases other than glaucoma. PubMed was used to perform a systematic review on the LC features that can be extracted from OCT images. All imaging features are presented and discussed in terms of their importance and applicability in clinical practice. A total of 56 studies were included in this review. Overall, LC depth (LCD) and thickness (LCT) have been the most studied features, appearing in 75% and 45% of the included studies, respectively. These biomarkers were followed by the prelaminar tissue thickness (21%), LC curvature index (5.4%), LC global shape index (3.6%), LC defects (3.6%), and LC strains/deformations (1.8%). Overall, the disease groups showed a thinner LC (smaller LCT) and a deeper ONH cup (larger LCD), with some exceptions. A large variability between approaches used to compute LC biomarkers has been observed, highlighting the importance of having automated and standardized methodologies in LC analysis. Moreover, further studies are needed to identify the pathologies where LC features have a diagnostic and/or prognostic value.

A neuroglia-based interpretation of glaucomatous neuroretinal rim thinning in the optic nerve head

Neuroretinal rim thinning (NRR) is a characteristic glaucomatous optic disc change. However, the precise mechanism of the rim thinning has not been completely elucidated. This review focuses on the structural role of the glioarchitecture in the formation of the glaucomatous NRR thinning. The NRR is a glia-framed structure, with honeycomb geometry and mechanically reinforced astrocyte processes along the transverse plane. When neural damage selectively involves the neuron and spares the glia, the gross structure of the tissue is preserved. The disorganization and loss of the glioarchitecture are the two hallmarks of optic nerve head (ONH) remodeling in glaucoma that leads to the thinning of NRR tissue upon axonal loss. This is in contrast to most non-glaucomatous optic neuropathies with optic disc pallor where hypertrophy of the glioarchitecture is associated with the seemingly absent optic disc cupping. Arteritic anterior ischemic optic neuropathy is an exception where pan-necrosis of ONH tissue leads to NRR thinning. Milder ischemia indicates selective neuronal loss that spares glia in non-arteritic anterior ischemic optic neuropathy. The biological reason is the heterogeneous glial response determined by the site, type, and severity of the injury. The neuroglial interpretation explains how the cellular changes underlie the clinical findings. Updated understandings on glial responses illustrate the mechanical, microenvironmental, and microglial modulation of activated astrocytes in glaucoma. Findings relevant to the possible mechanism of the astrocyte death in advanced glaucoma are also emerging. Ultimately, a better understanding of glaucomatous glial response may lead to glia-targeting neuroprotection in the future.

Bruch's Membrane Opening Minimum Rim Width in the Differential Diagnosis of Optic Neuropathies

Observing optic disc pallor during a patient's first visit frequently raises a diagnostic challenge, particularly in regards to whether the cause is due to glaucoma or another form of optic neuropathy. Bruch's membrane opening (BMO) was recently discovered as the anatomical border of the optic disc. BMO minimum rim width (BMO-MRW) seems to be a reliable representation of the neuroretinal rim. In our study, we demonstrate the ability of BMO-MRWs to differentiate between glaucomatous and non-glaucomatous. Additionally, we propose an MRW ratio which may allow discrimination of open angle glaucoma from either non-arteritic anterior ischaemic optic neuropathy or compressive optic neuropathy.

Disc Configuration as a Risk and Prognostic Factor in NAION: The Impact of Cup to Disc Ratio, Disc Diameter, and Crowding Index

Purpose: The presence of the so called disc at risk (a small disc with no cupping) has been considered the main risk factor for the development of non-arteritic anterior ischemic optic neuropathy (NAION). However its role as a prognostic factor has not been studied. Our aim was to determine the weight of disc configuration as a risk and a prognostic factor for NAION. Methods: Case control study. Forty eyes of 40 patients who were diagnosed with NAION between 2008 and 2017, and 120 controls (3 controls for each patient) were included in the study. Disc diameter (DD), cup to disc ratio (CDR), and peripapillar retinal nerve fiber layer thickness (RNFLT) of the non-affected eye were measured using optic coherence tomography (3D OCT 2000, Topcon). Crowding index (CI) was defined as the quotient of average RNFLT and disc area. Mean deviation (MD) at the time of diagnosis and at least three months later was determined using a Humphrey Visual Field Analyzer (SITA standard 24-2 strategy). Visual acuity (VA) was measured using Snellen charts and transformed into LogMAR values. Results: Only CDR was found to be a risk factor for NAION. No correlationship was found between CI and visual loss. Conclusions: DD and CI did not show value as either prognostic or risk factors. Glial tissue may be a part of the content of the optic disc as important as axons. Our results are in line with the latest studies about NAION pathophysiology. Contrary to classic thinking, these papers have not found smaller disc diameters, but smaller values of lamina cribosa depth in NAION patients.