Retinal ischemic cascade: New insights into the pathophysiology and imaging findings

RETINAL ISCHEMIC PERIVASCULAR LESIONS ARE ASSOCIATED WITH INCREASED CAROTID ARTERY STENOTIC DEGREE

PURPOSE

Retinal ischemic perivascular lesions (RIPLs) have been reported as potential biomarkers for cardiovascular diseases and stroke. The authors aimed to investigate the RIPLs in patients with carotid artery stenosis (CAS) and their association with stenotic degree.

METHODS

Patients with unilateral CAS or carotid artery occlusion were recruited. Optical coherence tomography was conducted for assessing the presence, number, and distribution of RIPLs. Optical coherence tomography angiography was used for evaluating microvascular density in superficial vascular complex and deep vascular complex.

RESULTS

Eight hundred and fifty-four eyes from 474 patients with CAS were included. Ipsilateral eyes had more PRILs compared with contralateral eyes (all P < 0.01). Patients with CAS with cerebral infarction had a higher incidence and broader distribution of RIPLs compared with those without infarction (both P < 0.05). The presence, number, and distribution of RIPLs were positively associated with stenotic degree (all P < 0.001). Eyes with RIPLs had lower superficial vascular complex density ( P = 0.020) compared with eyes without RIPLs.

CONCLUSION

Retinal ischemic perivascular lesions are anatomical markers of ischemia and are suggested to be associated with cerebral infarction and stenotic degree in patients with CAS. Optical coherence tomography/optical coherence tomography angiography is a noninvasive tool to detect retinal ischemic changes and quantitatively measure retinal microvascular changes in patients with CAS.

Paracentral Acute Middle Maculopathy (PAMM) in Ocular Vascular Diseases-What We Know and Future Perspectives

Paracentral acute middle maculopathy (PAMM) is a macular condition primarily detected using optical coherence tomography (OCT) imaging. It presents as hyperreflective bands within the inner nuclear layer (INL) of the retina, often leading to localized degenerative phenomena. PAMM is a condition that reveals a dysfunction in the microvascular network of the retina. However, it is not an isolated phenomenon but rather an indicator of deeper and even systemic, prevalently vascular-related issues related to a wide array of conditions that impact circulation, including retinal vein and artery occlusion, diabetic retinopathy, and hypertensive retinal vascular changes. PAMM occurs due to impaired perfusion within the retinal deep capillary plexus, clinically leading to subtle but noticeable blind spots (scotomas) in the central visual field. Recent advances in imaging technology, particularly optical coherence tomography angiography (OCTA), have provided a clearer view of the underlying vascular alterations. Thus, PAMM may currently serve as a biomarker in broader ocular and systemic pathologies before disease progression. This review explores the latest reports in the literature on PAMM, from its characteristic imaging features to the evolving theories behind its development. By bridging the gap between ophthalmology and systemic health, PAMM may facilitate earlier diagnosis and tailored management strategies for conditions that extend far beyond the eye. Understanding this entity could ultimately transform our approach to assessing vascular health toward further research, risk prediction, and patient care.

Detection of macular and peripheral ocular microvascular changes after carotid artery revascularization using widefield SS-OCTA

Purpose

This study aims to investigate microvascular changes in the macular and peripheral regions, as well as alterations in the foveal avascular zone (FAZ) of the ipsilateral eye using widefield swept-source optical coherence tomography angiography (SS-OCTA) in patients with severe carotid artery stenosis (SCAS) after carotid artery revascularization (CAR).

Design

This study employed a prospective study design.

Methods

SCAS patients were examined using widefield SS-OCTA, which covered an area of 16 × 16 mm centered on the fovea. These examinations were conducted both before and after CAR to assess changes in retinal and choroidal blood flow in the macular and peripheral regions, as well as alterations in the characteristics of the FAZ.

Results

A total of 56 patients and their corresponding 56 ipsilateral eyes were included in this study. In the macular area, a significant increase in the vessel density of the retinal superficial vascular complex (VDRSVC) was found, while a significant decrease was noted in the vessel density of the retinal deep vascular complex (VDRDVC) after CAR. Additionally, both the area and circumference of the FAZ decreased significantly after CAR. In the peripheral regions, significant increases were detected in both VDRSVC and the three-dimensional choroidal vascularity index (3D-CVI) post-CAR.

Conclusion

The findings of this study demonstrated that CAR can improve perfusion in both the macular and peripheral fundus and lead to a decreased area and circumference of the FAZ in the ipsilateral eye. The observed decrease in the VDRDVC after CAR may be attributed to microvascular embolization and ischemia within the deep capillary plexus (DCP).

Paracentral Acute Middle Maculopathy and Risk of Cardiovascular Disease, Stroke, and Death: A Longitudinal Study

PURPOSE

To evaluate the risk of acute cardiovascular events (CVE), including cardiovascular diseases, cerebrovascular diseases, and all-cause mortality in patients with paracentral acute middle maculopathy (PAMM).

DESIGN

Retrospective cohort study.

METHODS

We studied 43 individuals with optical coherence tomography-documented PAMM attending Moorfields Eye Hospital between January 2014 and June 2021. We excluded patients with preceding (<2 years) major adverse cardiac events. We stratified patients by age (<50 and ≥50 years) and whether associated with retinal vascular diseases (RVD) or isolated (iPAMM). We assessed risk factors, clinical characteristics, and visual prognosis of the patients. CVE risk was estimated using Kaplan-Meier curves, the log-rank test, and Cox proportional hazards regression.

RESULTS

In young patients with iPAMM patients (n = 12), underlying predisposing factors included six (50%) sickle cell disease and five (41.6%) others, including breakthrough bleeding in pregnancy, migraine, genetic cardiomyopathy, amphetamine use; among those with PAMM + RVD (n = 12) one (9%) had a vascular disorder, and four (44.4%) oral contraceptive use. In the older group of 20 patients, 15 (75%) had at least one coronary risk factor. During a median follow-up of 14 months (range 12-54), older subjects with iPAMM had a higher risk of developing CVE than those with PAMM + RVD (P < .001). Notably, iPAMM displayed a significantly earlier peak in peri-PAMM CVE risk compared to PAMM + RVD (median: one month, range 1-40 months vs 36 months, range 12-54 months). Relative to those with PAMM + RVD, risk of CVE was significantly higher in patients with iPAMM, adjusted for age and sex (hazard ratio: 6.37, 95% confidence interval 1.68-24.14, P = .017). No young patients experienced adverse CVE. At baseline, older iPAMM patients mean best corrected visual acuity of 0.7 (0-1.8) logarithm of the minimum angle resolution, which improved significantly to 0.2 (0-1.30) logarithm of the minimum angle resolution at the latest visit (P = .033).

CONCLUSIONS

Young individuals with iPAMM have a higher prevalence of predisposing factors compared to those presenting with combined PAMM + RVD. Older patients with iPAMM had a higher risk of CVE than those with PAMM + RVD, especially in the peri-onset timeframe. This suggests the need for a prompt cardiovascular assessment to rule out systemic etiologies and optimize cardiovascular risk factors, in addition to ongoing ophthalmology input.

From Nature to Treatment: The Impact of Pterostilbene on Mitigating Retinal Ischemia-Reperfusion Damage by Reducing Oxidative Stress, Inflammation, and Apoptosis

Retinal ischemia-reperfusion (I/R) injury is a critical pathogenic mechanism in various eye diseases, and an effective therapeutic strategy remains unresolved. Natural derivatives have recently reemerged; therefore, in our present study, we examined the potential therapeutic effects of a stilbenoid that is chemically related to resveratrol. Pterostilbene, recognized for its anti-inflammatory, anti-carcinogenic, anti-diabetic, and neuroprotective properties, counteracts oxidative stress during I/R injury through various mechanisms. This study explored pterostilbene as a retinoprotective agent. Male Sprague Dawley rats underwent retinal I/R injury and one-week reperfusion and were treated with either vehicle or pterostilbene. After this functional electroretinographical (ERG) measurement, Western blot and histological analyses were performed. Pterostilbene treatment significantly improved retinal function, as evidenced by increased b-wave amplitude on ERG. Histological studies showed reduced retinal thinning and preserved the retinal structure in the pterostilbene-treated groups. Moreover, Western blot analysis revealed a decreased expression of glial fibrillary acidic protein (GFAP) and heat shock protein 70 (HSP70), indicating reduced glial activation and cellular stress. Additionally, the expression of pro-apoptotic and inflammatory markers, poly(ADP-ribose) polymerase 1 (PARP1) and nuclear factor kappa B (NFκB) was significantly reduced in the pterostilbene-treated group. These findings suggest that pterostilbene offers protective effects on the retina by diminishing oxidative stress, inflammation, and apoptosis, thus preserving retinal function and structure following I/R injury. This study underscores pterostilbene's potential as a neuroprotective therapeutic agent for treating retinal ischemic injury and related disorders.

Integrated Assessment of OCT, Multimodal Imaging, and Cytokine Markers for Predicting Treatment Responses in Retinal Vein Occlusion Associated Macular Edema: A Comparative Review of Anti-VEGF and Steroid Therapies

Retinal vein occlusion (RVO) is a significant cause of vision loss, characterized by the occlusion of retinal veins, leading to conditions such as central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). Macular edema (ME), a prevalent consequence of RVO, is the primary cause of vision impairment in affected patients. Anti-VEGF agents have become the standard treatment, showing efficacy in improving visual acuity (VA) and reducing ME. However, a subset of patients exhibit a suboptimal response to anti-VEGF therapy, necessitating alternative treatments. Corticosteroids, which address inflammatory pathways implicated in ME, have shown promise, particularly in cases resistant to anti-VEGF. This review aims to identify biomarkers that predict treatment response to corticosteroids in RVO-associated ME, utilizing multimodal imaging and cytokine assessments. Baseline imaging, including SD-OCT and OCT-A, is essential for evaluating biomarkers like hyperreflective foci (HRF), serous retinal detachment (SRF), and central retinal thickness (CRT). Elevated cytokine levels, such as IL-6 and MCP-1, correlate with ME severity and poor anti-VEGF response. Early identification of these biomarkers can guide timely transitions to corticosteroid therapy, potentially enhancing treatment outcomes. The practical conclusion of this review is that integrating biomarker assessment into clinical practice enables personalized treatment decisions, allowing for earlier and more effective management of RVO-associated ME by transitioning patients to corticosteroid therapy when anti-VEGF agents are insufficient. Advanced diagnostics and machine learning may further refine personalized treatment strategies, improving the management of RVO-associated ME.

Optical coherence tomography angiography suggests choriocapillaris perfusion deficit as etiology of acute macular neuroretinopathy

PURPOSE

Acute macular neuroretinopathy (AMN) can cause sudden-onset and permanent scotoma in healthy young patients. Analysis of optical coherence tomography (OCT) and OCT angiography (OCTA) of AMN patients may provide insights into disease mechanism.

METHODS

We conducted a retrospective study of consecutive SARS-Cov-2-related AMN patients that presented in our clinic between Jan 1st, 2022, and April 30th, 2023, within 30 days of symptom onset. Retinal vessel area density (VAD) of AMN lesions in OCTA was quantified and compared to an adjacent tissue control (ATC). This quantification was performed for the superficial vascular plexus (SVP), the intermediate capillary plexus (ICP), the deep capillary plexus (DCP), the choriocapillaris (CC), and choroid. Furthermore, en face OCT images were analyzed.

RESULTS

Nine AMN patients were identified, 6 of these (4 female, 2 male, average age 25 years) fulfilled the inclusion criteria and were included into this study. Average time from symptom onset to OCTA was 14.3 days. No VAD differences between AMN and adjacent tissue were found in either retinal layer (SVP, ICP, DCP). In contrast, VAD in CC was reduced by 27% against the ATC (p = 0.007) and choroidal VAD was reduced by 41% (p = 0.017). Further analysis of en face OCT could show that the pathognomonic infrared hyporeflectivity in AMN is caused by photoreceptor alterations rather than changes in the inner retinal layers.

CONCLUSIONS

Our data suggests that a perfusion deficit in the choroidal layers is responsible for AMN rather than in the DCP, which is the predominant hypothesis in current literature.

Bilateral nonarteritic ischemic optic neuropathy and retinal ischemia in a pediatric dialysis patient

A nearly 3-year-old boy on nightly dialysis presented emergently with sudden loss of vision. On examination, his visual acuity was light perception in the right eye and no light perception in the left eye. There was bilateral optic disk edema, diffuse pallor of posterior poles, and a cherry red spot in the left fundus. The patient was subsequently found to be hemodynamically unstable and admitted to the pediatric intensive care unit with presumed septic shock. Optical coherence tomography revealed paracentral acute middle maculopathy lesions in the right eye and diffusely thick retina in the left eye. Magnetic resonance imaging and magnetic resonance angiography of the brain and vessels did not reveal any acute findings. The patient's presentation was most consistent with bilateral nonarteritic ischemic optic neuropathy and unilateral central retinal artery occlusion. On repeat evaluation 9 months later, vision was largely unchanged.

Optimization of an Ischemic Retinopathy Mouse Model and the Consequences of Hypoxia in a Time-Dependent Manner

The retina is one of the highest metabolically active tissues with a high oxygen consumption, so insufficient blood supply leads to visual impairment. The incidence of related conditions is increasing; however, no effective treatment without side effects is available. Furthermore, the pathomechanism of these diseases is not fully understood. Our aim was to develop an optimal ischemic retinopathy mouse model to investigate the retinal damage in a time-dependent manner. Retinal ischemia was induced by bilateral common carotid artery occlusion (BCCAO) for 10, 13, 15 or 20 min, or by right permanent unilateral common carotid artery occlusion (UCCAO). Optical coherence tomography was used to follow the changes in retinal thickness 3, 7, 14, 21 and 28 days after surgery. The number of ganglion cells was evaluated in the central and peripheral regions on whole-mount retina preparations. Expression of glial fibrillary acidic protein (GFAP) was analyzed with immunohistochemistry and Western blot. Retinal degeneration and ganglion cell loss was observed in multiple groups. Our results suggest that the 20 min BCCAO is a good model to investigate the consequences of ischemia and reperfusion in the retina in a time-dependent manner, while the UCCAO causes more severe damage in a short time, so it can be used for testing new drugs.

Retinal Ischemic Perivascular Lesion Reflects Cerebral Small Vessel Disease Burden in Single Subcortical Infarction

BACKGROUND

Retinal ischemic perivascular lesions (RIPLs) are an indicator of ischemia in the middle retina. We aimed to determine the relationship between RIPLs and single subcortical infarction (SSI). We also investigated the differences in cerebral small vessel disease imaging burden between groups with and without RIPLs in SSI.

METHODS AND RESULTS

In this case-control study, we enrolled 82 patients with SSI and 72 nonstroke controls. All participants underwent magnetic resonance imaging and swept-source optical coherence tomography/optical coherence tomography angiography. Small vessel disease markers such as lacunes, cerebral microbleeds, white matter hyperintensity, and perivascular spaces were rated on brain imaging. RIPLs were assessed via swept-source optical coherence tomography. Optical coherence tomography angiography was used to measure the superficial vascular complex and deep vascular complex of the retina. After adjusting for risk factors, the presence of RIPLs was significantly associated with SSI (odds ratio [OR], 1.506 [95% CI, 1.365-1.662], P<0.001). Eyes with RIPLs showed lower deep vascular complex density (P=0.035) compared with eyes without RIPLs in patients with SSI. After adjusting for vascular risk factors, the presence of RIPLs in patients with SSI was associated with an increased periventricular white matter hyperintensity burden (β=0.414 [95% CI, 0.181-0.647], P<0.001) and perivascular spaces-basal ganglia (β=0.296 [95% CI, 0.079-0.512], P=0.008).

CONCLUSIONS

RIPLs are associated with SSI independent of underlying risk factors. The relationship between the presence of RIPLs and small vessel disease markers provides evidence that RIPLs might be an additional indicator of cerebral ischemic changes.

Prevalence and Distribution of Macular Fluid with Central Retinal Artery Occlusion and Anterior Ischemic Optic Neuropathy

Purpose

To examine the prevalence and distribution of fluid within a cohort of eyes with acute central retinal artery occlusion (CRAO) and non-arteritic anterior ischemic optic neuropathy (AION) using optical coherence tomography (OCT).

Methods

A retrospective analysis of patient records and OCT imaging. Patients presenting with acute CRAO or AION who had available macular OCT imaging and no co-morbidities known to cause macular fluid were included in the analysis. Baseline characteristics, visual acuity (VA), and fluid presence and distribution among the retinal layers were recorded.

Results

In the 16 eyes with acute CRAO, fluid was noted in 5 eyes (31%), which was mainly subretinal (3 eyes) or intraretinal located within the outer retinal layers (3 eyes). Only one eye had inner retinal cysts. Of the 11 eyes with acute AION, fluid was present in 8 eyes (73%). Subretinal fluid was noted in 4 eyes and extended to the foveal area in 3 of them, and outer retinal versus inner retinal cysts were noted in 6 versus 3 eyes, respectively. None of the eyes showed hard exudate deposition. In the small subset of eyes with CRAO and macular fluid that were followed-up, VA improved, while in eyes with AION, VA remained stable.

Conclusion

Macular fluid on OCT is not an uncommon feature of acute CRAO and AION and is mainly distributed within the outer retinal layers or subretinal space. Fluid is an understudied feature of retinal and optic nerve head infarction and may have a role in predicting neuronal damage extent and visual outcome.

Sequential Bilateral Paracentral Acute Middle Maculopathy in a Middle-Aged Woman

Purpose: To present a case of sequential paracentral acute middle maculopathy (PAMM) in a middle-aged woman with no cardiovascular risk factors. Methods: A single case was evaluated. Results: A 53-year-old woman with a history of PAMM resulting from perfused central retinal artery occlusion in the left eye presented with PAMM in the right eye 3 years later. The patient had a medical history of treated anemia, stress disorder, and insomnia. Examination of the right eye showed a superior parafoveal crescent of translucent retina without associated edema or hemorrhage. Optical coherence tomography (OCT) showed hyperreflective band-like areas in the superior parafoveal and perifoveal regions. Fluorescein angiography revealed normal arterial filling. OCT angiography showed patchy filling of the middle capillary plexus with normal perfusion of the superficial capillary plexus in the right eye. Conclusions: Although bilateral sequential PAMM is rare, close monitoring in a case of PAMM in 1 eye should be considered.