Multimodal imaging in acute retinal ischemia: spectral domain OCT, OCT-angiography and fundus autofluorescence

Ibudilast Protects Retinal Bipolar Cells from Excitotoxic Retinal Damage and Activates the mTOR Pathway

Ibudilast, an inhibitor of macrophage migration inhibitory factor (MIF) and phosphodiesterase (PDE), has been recently shown to have neuroprotective effects in a variety of neurologic diseases. We utilize a chick excitotoxic retinal damage model to investigate ibudilast's potential to protect retinal neurons. Using single cell RNA-sequencing (scRNA-seq), we find that MIF, putative MIF receptors CD74 and CD44, and several PDEs are upregulated in different retinal cells during damage. Intravitreal ibudilast is well tolerated in the eye and causes no evidence of toxicity. Ibudilast effectively protects neurons in the inner nuclear layer from NMDA-induced cell death, restores retinal layer thickness on spectral domain optical coherence tomography, and preserves retinal neuron function, particularly for the ON bipolar cells, as assessed by electroretinography. PDE inhibition seems essential for ibudilast's neuroprotection, as AV1013, the analogue that lacks PDE inhibitor activity, is ineffective. scRNA-seq analysis reveals upregulation of multiple signaling pathways, including mTOR, in damaged Müller glia (MG) with ibudilast treatment compared to AV1013. Components of mTORC1 and mTORC2 are upregulated in both bipolar cells and MG with ibudilast. The mTOR inhibitor rapamycin blocked accumulation of pS6 but did not reduce TUNEL positive dying cells. Additionally, through ligand-receptor interaction analysis, crosstalk between bipolar cells and MG may be important for neuroprotection. We have identified several paracrine signaling pathways that are known to contribute to cell survival and neuroprotection and might play essential roles in ibudilast function. These findings highlight ibudilast's potential to protect inner retinal neurons during damage and show promise for future clinical translation.

Optical Coherence Tomography Findings in Cherry-Red Spot: Implications for Understanding Pathophysiology and Visual Prognosis

PURPOSE

To report optical coherence tomography (OCT) findings of cherry-red spots from Tay-Sachs and Niemann-Pick disease.

METHODS

Consecutive patients with Tay-Sachs and Niemann-Pick disease evaluated by the pediatric transplant and cellular therapy team, for whom a handheld OCT scan was obtained, were included. Demographic information, clinical history, fundus photography, and OCT scans were reviewed. Two masked graders evaluated each of the scans.

RESULTS

The study included 3 patients with Tay-Sachs disease (5, 8, and 14 months old) and 1 patient with Niemann-Pick disease (12 months old). All patients had bilateral cherry-red spots on fundus examination. In all patients with Tay-Sachs disease, handheld OCT revealed parafoveal ganglion cell layer (GCL) thickening, increased nerve fiber layer, and GCL reflectivity, and different levels of residual normal signal GCL. The patient with Niemann-Pick disease had similar parafoveal findings, but there was a thicker residual GCL. Sedated visual evoked potentials were unrecordable in all 4 patients despite 3 of them demonstrating normal visual behavior for age. Patients with good vision had relative sparing of the GCL on OCT.

CONCLUSIONS

The cherry-red spots in lysosomal storage diseases appear as perifoveal thickening and hyperreflectivity of the GCL on OCT. In this case series, residual GCL with normal signal proved to be a better biomarker for visual function than visual evoked potentials and could be considered for future therapeutic trials. [J Pediatr Ophthalmol Strabismus. 2023;60(6):435-440.].

Visual acuity assessment of central retinal artery occlusion patients with or without paracentral acute middle maculopathy via OCT-A

PURPOSE

The association between paracentral acute middle maculopathy (PAMM) and visual acuity in patients with central retinal artery occlusion (CRAO) is still unclear. The present study investigated the visual acuity of CRAO patients with and without PAMM.

METHODS

CRAO patients with PAMM or without PAMM were included. Optical coherence tomography angiography (OCT-A) was used to record the macular retinal thickness and density of shallow and deep vessels. The Best-corrected visual acuity (BCVA) was converted to a logarithm of the minimum angle of resolution (LogMAR) for statistical analysis.

RESULTS

There were 34 CRAO patients with PAMM (43.13%), other 30 CRAO patients without PAMM (46.87%). Compared with the no-PAMM group, PAMM group had better LogMAR BCVA (1.48 (0.49, 1.85) Vs. 1.85 (1.70, 1.96), P < 0.01). There was also a significant difference in retinal thickness of the central macular sulcus (328.00 (304.50-332.25) Vs. 352.50 (311.75-420.50), P = 0.01). A significant correlation between LogMAR BCVA and macular retinal thickness was found (r = 0.42; P < 0.01).

CONCLUSION

CRAO patients with PAMM had significantly better visual acuity and less macular edema. OCT-A can be used to distinguish different levels of damage due to CRAO.

Quantitative Wide-Field Swept-Source Optical Coherence Tomography Angiography and Visual Outcomes in RAO

Purpose

Retinal artery occlusion (RAO) is an ophthalmic emergency that can lead to poor visual outcomes and is associated with an increased risk of stroke and cardiovascular events. Wide-field swept-source OCT-A (WF SS-OCTA) can provide quick and non-invasive angiographic information with a wide field of view. Here, we looked for associations between OCT-A vascular imaging metrics and vision in RAO patients.

Methods

Patients with diagnoses of central (CRAO) or branched retinal artery occlusion (BRAO) were included. 6mm × 6mm Angio and 15mm × 15mm AngioPlex Montage OCT-A images were obtained for both eyes in each patient using Zeiss Plex Elite 9000 WF SS-OCTA device. Each 6mm × 6mm image was divided into nine Early Treatment Diabetic Retinopathy Study (ETDRS) subfields. Non-perfusion area (NPA) was manually measured using 15mm × 15mm images. A linear regression model was utilized to identify correlation between imaging metrics and vision. P-values less than 0.05 were considered as statistically significant.

Results

Twenty-five subjects were included. For RAO eyes, there was a statistically significant inverse correlation between retinal thickness as well as superficial capillary plexus (SCP) vessel density (VD) and vision. An inverse correlation was found between deep capillary plexus (DCP) VD and vision without statistical significance. There was a positive correlation between choroidal thickness as well as choroidal volume and vision without statistical significance. No significant correlation was found between the metrics and vision in contralateral eyes. For NPA and vision, no significant correlation was identified.

Conclusion

This is the first study to investigate the utility of WF SS-OCTA in RAO and to demonstrate correlations between retinal vascular imaging metrics and visual outcomes. The results of this study provide a basis to understand the structural changes involved in vision in RAO and may guide management of RAO and prevention of cerebral stroke and cardiovascular accidents.

[Visualization of retinal blood flow disturbances in acute retinal ischemia syndrome]

Vascular disorders account for a significant proportion of acute loss of vision. In recent years, scientific and technical progress in ophthalmology has provided new opportunities in the study of vascular pathology, significantly expanding the understanding of their pathogenesis. The article presents a clinical case of a patient with acute retinal ischemia syndrome who had retinal blood flow disturbances studied using optical coherence tomography (OCT) imaging. It demonstrates extensive possibilities of diagnostics of ischemic retinal lesions using OCT angiography that make this method the most informative in terms of evaluating the blood flow at different levels, independently in each vascular plexus.

Multimodal Imaging of Acute Central Retinal Artery Occlusion

The aim of this study was to describe fluorescein angiography (FA), ocular coherence tomography (OCT) and ocular coherence tomography angiography (OCTA) in the diagnosis of acute central retinal artery occlusion (CRAO). This is an observational case series study performed at Sohag Ophthalmic Investigation Center. Fifteen patients presented by a sudden marked unilateral diminution of vision were included. Corrected Distance Visual acuity (CDVA), color fundus photos, FA, OCT and OCTA, imaging obtained in the first week of presentation and imaging of the other normal eye as a control were assessed. Central macular thickness (CMT), parafoveal inner retinal layers thickness and parafoveal outer retinal thickness in diseased and contralateral normal eyes were compared. Fifteen patients (mean age 52.67 years, 11-74 years old) including 66.7% male entered the study. CDVA ranged from no perception of light to 0.05 (20/400). Fundus examination showed a cherry red spot in 10 cases (66.7 %) and retinal whitening in 9 cases (60%), arteriolar narrowing in 7 (46.67%), optic disc edema in 4 (26.67%), optic disc pallor in 5 (33.3%) and cattle trucking in 5 (33.3%). Fluorescein angiography showed delayed arteriovenous transit time > 23 seconds in 8 cases (53.33 %) and normal FA in 4 cases (26.67 %). OCT revealed increased hyperreflective of the inner retinal layers in comparison to hyporeflective inner retinal layers in all cases (100%) and significant increase in CMT in 10 cases (66.67%). The mean ± standard deviation (SD) of CMT (CRAO) was 306.5 ± 27.9 (P < 0.001), the parafoveal inner retinal thickness (CRAO) 345 ± 51.8 µm (P < 0.001) and the parafoveal outer retinal thickness (CRAO) 120.9 ± 13.6 µm (P < 0.001). OCTA was performed and clear images obtained in 11 cases (73.33%). Disruption of superficial and deep capillary plexus was found in all cases. We concluded that the OCT is the most confirmative imaging method in the diagnosis of acute CRAO even in the absence of fundus signs. OCTA confirms the diagnosis, but it cannot be performed in some cases.

The Utility of Fundus Fluorescein Angiography in Neuro-Ophthalmology

While its use is still widespread within the medical retina field, fundus fluorescein angiography (FFA) is increasingly falling out of favour in the investigation of neuro-ophthalmological disease, with the introduction of new technologies, particularly optical coherence tomography. FFA does, however, provide useful diagnostic and prognostic information in many neuro-ophthalmological diseases including papilloedema, pseudo-papilloedema, optic neuropathies and central retinal artery occlusion to name a few. We aim to summarise the main FFA findings in each of these conditions and highlight where FFA is of most use in providing complementary information to other modes of investigation.