Evidence for an enduring ischaemic penumbra following central retinal artery occlusion, with implications for fibrinolytic therapy

Early REperfusion therapy with intravenous alteplase for recovery of VISION in acute central retinal artery occlusion (REVISION): Study protocol of a phase III trial

RATIONALE

Meta-analyses of case series of non-arteritic central retinal artery occlusion (CRAO) indicate beneficial effects of intravenous thrombolysis when initiated early after symptom onset. Randomized data are lacking to address this question.

AIMS

The REperfusion therapy with intravenous alteplase for recovery of VISION in acute central retinal artery occlusion (REVISION) investigates intravenous alteplase within 4.5 h of monocular vision loss due to acute CRAO.

METHODS

This study is the randomized (1:1), double-blind, placebo-controlled, multicenter adaptive phase III trial.

STUDY OUTCOMES

Primary outcome is functional recovery to normal or mildly impaired vision in the affected eye defined as best-corrected visual acuity of the Logarithm of the Minimum Angle of Resolution of 0.5 or less at 30 days (intention-to-treat analysis). Secondary efficacy outcomes include modified Rankin Score at 90 days and quality of life. Safety outcomes include symptomatic intracranial hemorrhage, major bleeding (International Society on Thrombosis and Haemostasis definition) and mortality. Exploratory analyses of optical coherence tomography/angiography, ultrasound and magnetic resonance imaging (MRI) biomarkers will be conducted.

SAMPLE SIZE

Using an adaptive design with interim analysis at 120 patients, up to 422 participants (211 per arm) would be needed for 80% power (one-sided alpha = 0.025) to detect a difference of 15%, assuming functional recovery rates of 10% in the placebo arm and 25% in the alteplase arm.

DISCUSSION

By enrolling patients within 4.5 h of CRAO onset, REVISION uses insights from meta-analyses of CRAO case series and randomized thrombolysis trials in acute ischemic stroke. Increased rates of early reperfusion and good neurological outcomes in stroke may translate to CRAO with its similar pathophysiology.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04965038; EU Trial Number: 2023-507388-21-00.

Paracentral acute middle maculopathy in a patient with Myelin Oligodendrocyte glycoprotein antibody associated optic neuritis

Purpose

There is insufficient literature reporting the concurrent occurrence of retinal ischemic lesions with optic neuritis. In this case report, we present a distinctive instance of Optic Neuritis with a positive Myelin Oligodendrocyte glycoprotein (MOG) antibody, accompanied by retinal ischemia manifesting as paracentral acute middle maculopathy (PAMM) lesions.

Observations

Our patient is a 25-year-old female who tested positive for MOG antibodies and exhibited retinal PAMM lesions without any apparent underlying ischemic cause. She received intravenous pulse steroid therapy, and her symptoms and signs completely resolved one month later.

Conclusion

PAMM can serve as an initial manifestation of Myelin Oligodendrocyte glycoprotein Antibody Associated Disease (MOGAD). This case has the potential to contribute to the existing literature, facilitating a deeper exploration of the pathophysiology of retinal ischemia in MOG associated optic neuritis.

Exploring Superselective Intraarterial Thrombolysis for Autologous Fat Injection-Induced Vision Loss

BACKGROUND

Intravascular injection represents the most severe complication in fat transplantation procedures. Currently, the prognosis for patients who suffer from blindness due to fat transplantation-induced ocular vascular occlusion is far from optimistic.

OBJECTIVES

The aim of this study was to explore and evaluate the efficacy and safety of arterial thrombolysis in the treatment of ocular vascular occlusion caused by fat transplantation.

METHODS

We analyzed the data of 12 patients who underwent intraarterial thrombolysis and conservative treatments for facial autologous fat grafting-associated ocular vascular occlusion. Among the cases, there were 6 instances of ophthalmic artery embolism and 6 cases of central retinal artery occlusion. All patients suffered with sudden blindness, sometimes accompanied by eye pain, ptosis, strabismus, skin necrosis at the injection site, or cerebral microinfarction. They received symptomatic conservative treatments and intraarterial thrombolysis, encompassing mechanical vessel recanalization, vessel dilation, and dissolution of thrombus constituents.

RESULTS

Following intraarterial thrombolysis, a noteworthy improvement in the blood flow of both the main trunk and peripheral branches of the ophthalmic artery was observed in the majority of patients when contrasted with their pretreatment status. One patient experienced a headache intraoperatively, while no significant discomfort was reported by the remaining patients. After conservative treatments and intraarterial thrombolysis, all patients experienced improvement in ocular symptoms, skin necrosis, and cerebral infarction. Three patients demonstrated improvement in visual acuity. These patients had surpassed the recommended time window for treatment, yet the occlusion of the ophthalmic artery was not complete.

CONCLUSIONS

Intraarterial thrombolysis combined with conservative treatments achieves early perfusion and is expected to promote visual recovery. Hospitals that possess the necessary treatment capabilities are encouraged to establish this therapeutic pathway.

Improved visual outcomes of central retinal artery occlusion with local intra-arterial fibrinolysis beyond the conventional time window

Local intra-arterial fibrinolysis (LIF) is a promising therapeutic option for CRAO. However, the narrow time window of 6 h has greatly limited the application of LIF. In this study, we explored the efficacy of LIF beyond the conventional time windows and compared the result with conservative therapy. This prospective study included 179 CRAO patients with baseline visual acuity (VA) ≤ 20/400 treated at Renmin Hospital of Wuhan University. The mean time from vision loss to presentation was 5.5 days. 58 patients received conventional standard therapy (CST) alone.121 patients underwent LIF. Main outcome was VA improvement ≥ 0.3 logMAR. Secondary outcome was a favorable VA outcome of 20/200 or better. Logistic regressions were performed to identify predictors of visual improvement. 43% patients in the LIF group experienced VA improvement versus 19% with CST (P = 0.002). LIF was associated with 4.0-fold higher likelihood of visual improvement compared to CST (P = 0.001). Poor baseline VA (light perception or no light perception) and shortened prothrombin time (PT) were associated with greater chance of visual improvement with LIF. However, LIF showed no significant advantage over CST for favorable VA outcomes. No major complications occurred. LIF beyond the therapeutic time window improved vision in functionally blind CRAO patients and showed better efficacy when compared with CST. PT may be a potential predictor of visual outcome after LIF. Our findings could complement existing time-based treatment guidelines and potentially allow for personalized decisions on the use of LIF beyond time windows.

Long-term outcomes of intravenous fibrinolysis in central retinal artery occlusion

Central retinal artery occlusion (CRAO) is an ophthalmologic emergency that can lead to irreversible loss of vision. Intravenous thrombolysis (IVT) has been used experimentally for its treatment. Our study aimed to evaluate the effect of emergency IVT on CRAO and its impact on visual acuity outcomes. We conducted a retrospective observational study of patients with CRAO. A total of 46 patients with CRAO were analysed; 16 patients received IVT treatment (IVT group) while 30 did not (no-IVT group). Seven patients from the IVT group received IVT early, within 4.5 hours (h) after the onset of symptoms (early-IVT), and 9 patients received it beyond this timeframe (late-IVT). The median time-to-hospital was 8.5 h: 3 h for the IVT group and 24 h for the no-IVT group. The median time-to-treatment was 5 h. The median outcome of visual acuity was 0.05 in the early-IVT, 0.025 in the late-IVT, and 0.01 in the no-IVT group. Among patients who received IVT early, 86% exhibited significant visual improvement. This improvement was four-fold greater compared to all other groups (p = 0.040), including the late-IVT (p = 0.011) and no-IVT groups (p = 0.023). No complications of the treatment were reported. Our study confirms that the administration of IVT treatment for CRAO within the 4.5-h time window is both safe and effective.

Characterising collateral vessels in eyes with branch retinal vein occlusions using widefield swept-source optical coherence tomography angiography

BACKGROUND/AIMS

To characterise the morphology, location and functional significance of both macular and extramacular collateral vessels (CVs) in patients with a history of branch retinal vein occlusion (BRVO) using widefield swept-source optical coherence tomography angiography (WF SS OCTA).

METHODS

Patients with a history of BRVO underwent WF SS OCTA testing to acquire 12×12 mm images, which were evaluated for CVs and non-perfusion area (NPA). Region of interest analysis of individual CVs was performed to identify correlations between CV size, depth and retinal location. Mixed effects multivariate regression analyses of factors associated with NPA and visual acuity (VA) were performed.

RESULTS

Fifty-five CVs were identified in 28 BRVO eyes from 27 patients. CVs were identified in 42.9% (12/28) of eyes with a history of BRVO, and of these, 45.5% (25/55) were extramacular. The majority of CVs (87.3%, 48/55) coursed through both the superficial and the deep capillary plexus (DCP), while a subset (12.7%, 7/55) were strictly superficial. No CVs were found to course strictly through the DCP alone. CV depth increased with distance from the optic disc (p=0.011) and CV size increased with distance from the fovea (p=0.005). There were no statistically significant associations between CVs and NPA, or between CVs and VA.

CONCLUSIONS

WF SS OCTA revealed that a large fraction of CVs that form after BRVO are extramacular, and the morphology of CVs varies as a function of retinal location. Depth-resolved study of CVs may offer valuable insights on the pathophysiological mechanisms leading to the development of macular oedema.

The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

Neuroprotection for Nonarteritic Central Retinal Artery Occlusion: Lessons from Acute Ischemic Stroke

Nonarteritic central retinal artery occlusion (NA-CRAO) is a variant of acute ischemic stroke (AIS) and is a cause of sudden severe loss of vision. There are guidelines by the American Heart Association and the American Stroke Association for the care of CRAO patients. This review explores the basis of retinal neuroprotection for CRAO and its potential for improving the outcome of NA-CRAO. Recently, there have been significant advances in research into the use of neuroprotection to treat retinal diseases, including retinal detachment, age-related macular degeneration, and inherited retinal diseases. Also, neuroprotective research in AIS has been extensive, and newer drugs tested, including Uric acid, Nerinetide, and Otaplimastat, with promising results. Progress in cerebral neuroprotection after AIS offers hope for retinal neuroprotection after CRAO; and a possibility of extrapolating research findings from AIS into CRAO. Combining neuroprotection and thrombolysis can extend the therapeutic window for NA-CRAO treatment and potentially improve outcomes. Experimented neuroprotection for CRAO includes Angiopoietin (Comp Ang1), KUS 121, Gene therapy (XIAP), and hypothermia. Efforts in the field of neuroprotection for NA-CRAO should focus on better imaging to delineate the penumbra after an acute episode of NA-CRAO (using a combination of high-definition optical coherence angiography and electrophysiology). Also, research should explore details of pathophysiologic mechanisms involved in NA-CRAO, allowing for further neuroprotective intervention, and closing the gap between preclinical and clinical neuroprotection.

The accumulated oxygen deficit as an indicator of the ischemic retinal insult

We here attempt to improve quantification of the ischemic retinal insult, that is, what is imposed on the retinal tissue by ischemia, especially in experimental models of ischemia. The ischemic retinal insult initiates the ischemic retinal injury (or outcome). Accordingly, it is reasonable to assume that the better the quantification of the insult, the better the correlation with, and thereby estimation of, the injury. The insult seldom has been quantified in terms of the relevant physiological factors, especially in connection with the rate of oxygen delivery (DO2). We here propose the accumulated oxygen deficit (AO2D) as an indicator of the ischemic retinal insult. We hypothesized that AO2D is correlated with the rate of oxygen metabolism measured 1 h after reperfusion following an episode of ischemia (MO2_1_Hr). Previously, we showed that MO2_1_Hr is related to the electroretinogram amplitude and the retinal thickness when they are measured seven days after reperfusion. We studied 27 rats, as well as 26 rats from our published data on retinal ischemia in which we had measurements of DO2 and duration of ischemia (T) of various levels and durations. We also measured DO2 in 29 rats treated with sham surgery. Ischemia was induced by either ipsilateral or bilateral common carotid artery occlusion or by ophthalmic artery occlusion, which gave a wide range of DO2. DO2 and MO2_1_Hr were evaluated based on three types of images: 1) red-free images to measure vessel diameters, 2) fluorescence images to estimate blood velocities by the displacement of intravascular fluorescent microspheres over time, and 3) phosphorescence images to quantify vascular oxygen tension from the phosphorescence lifetime of an intravascular oxygen sensitive phosphor. Loss of oxygen delivery (DO2L) was calculated as the difference between DO2 under normal/sham condition and DO2 during ischemia. AO2D, a volume of oxygen, was calculated as the product DO2L and T. Including all data, the linear relationship between AO2D and MO2_1_Hr was significant (R2 = 0.261, P = 0.0003). Limiting data to that in which T or DO2L was maximal also yielded significant relationships, and revealed that DO2L at a long duration of ischemia contributed disproportionately more than T to MO2_1_Hr. We discuss the potential of AO2D for quantifying the ischemic retinal insult, predicting the ischemic retinal injury and evaluating the likelihood of infarction.

Long-term Prognosis of Vision Loss Caused by Facial Hyaluronic Acid Injections and the Potential Approaches to Address This Catastrophic Event

BACKGROUND

Vision loss is a serious complication of hyaluronic acid (HA) filler injections, and long-term observations regarding the prognosis, particularly with angiography, are rare.

OBJECTIVES

This study aimed to investigate the long-term prognosis and living status of patients with visual defects due to HA filler injections.

METHODS

Nine patients with vision loss caused by HA filler injections and receiving different treatments were included and followed up for 2 to 6 years after their accident. Follow-ups, including outpatient ophthalmologic examinations, were performed.

RESULTS

In the follow-up observation, all patients had reintegrated into society and work. The prognosis was similar for all hyaluronidase treatments, including retrobulbar injections and superselective ophthalmic artery thrombolysis. The facial appearance was not remarkably affected, and only 3 patients reported slight scarring. Ptosis disappeared in all the patients, and slight strabismus was found in 5 patients. However, vision improvement was very limited, even in the patients whose occluded retinal central artery received reperfusion.

CONCLUSIONS

This long-term follow-up showed that the patients with vision loss caused by HA filler injections could reintegrate into society after treatment. Although the embolization of the retinal central artery led to reperfusion, vision was not restored, which further demonstrated the difficulty of recovering vision with the current treatment and the importance of prophylaxis. Autohydrolysis of HA by incorporating hyaluronidase-containing stimuli-responsive nanoparticles and a dual-pipe syringe are potential future approaches to address this catastrophic event.

Retinal vascular occlusion in pregnancy: three case reports and a review of the literature

Background

Retinal arterial occlusive events in young patients are rare. However, because of physiological multifactorial adaptations during pregnancy, retinal vascular occlusive disease may occur spontaneously. In addition, a patent foramen ovale is a risk factor for an ischemic thromboembolic event. Since fluorescein angiography, a central tool in the evaluation of these occlusions, should be avoided during pregnancy, optical coherence tomography angiography, a novel technique, offers a good opportunity for visualizing vascular perfusion of retinal tissue.

Case presentation

Here we present a case series of three patients (Caucasian, nonsmoker) who visited our clinic owing to acute visual impairment and central scotoma. Using regular optical coherence tomography and optical coherence tomography angiography, retinal vascular occlusions were detected, thus initiating the evaluation of systemic risk factors. We report two patients (30 and 32 years old) who developed cilioretinal artery occlusion but whose etiology differed: one was of thromboembolic origin associated with patent foramen ovale, while the other was caused by hemodynamic blockade secondary to central retinal vein occlusion. In both cases, optical coherence tomography angiography revealed reperfusion of the cilioretinal artery occlusion. However, transient ischemia led to retinal atrophy after a few weeks. In the third patient (32 years old), 8 weeks after onset of scotoma, optical coherence tomography angiography revealed atrophy of the middle layers and impaired perfusion in the deep capillary plexus, and thus a paracentral acute middle maculopathy was diagnosed. All patients regained normal visual acuity and had otherwise uncomplicated pregnancies, and laboratory blood tests did not reveal any defects or alterations.

Conclusions

As shown here, optical coherence tomography angiography enables risk-free imaging of retinal vessel perfusion during pregnancy. Together with regular optical coherence tomography, it allows one to predict functional outcome according to the existing retinal occlusion-related atrophy.

Paracentral Acute Middle Maculopathy and Central Retinal Venous Occlusion following Electrical Injury

Purpose

To report a case of central retinal vein occlusion (CRVO) and paracentral acute middle maculopathy (PAMM) following electric shock injury. Case Description. A 45-year-old male presented with a significant painless decreased vision in the right eye following an electrical injury of the right hand in his workplace. The best-corrected visual acuity (BCVA) of the right eye was 20/40. Funduscopic examination of the right eye revealed diffuse superficial and deep intraretinal hemorrhages, mild venous tortuosity, and an area of the pale retina. Optical coherence tomography (OCT) demonstrated hyperreflective band-like lesions in the middle retinal layers. Patchy areas of vascular flow void in deep capillary plexus seen in OCT angiography of the right eye were compatible with PAMM. Fluorescein angiography of the right eye was indicative of delayed venous filling suggestive of CRVO. The left eye was completely normal on exam and imaging.

Conclusion

This report illustrates the occurrence of CRVO associated with PAMM following electric shock injury. Electrical injury leads to a wide range of retinal manifestations. Clinicians need to pay attention to any hyperreflectivity and thinning of middle retinal layers in OCT in cases with the presentation of sudden visual loss following electrical injuries.

Paracentral Acute Middle Maculopathy and the Ischemic Cascade: Toward Interventional Management

PURPOSE

To present select cases of paracentral acute middle maculopathy (PAMM) demonstrating progressive vascular occlusion and the ischemic cascade and illustrate scenarios in which therapeutic intervention may be considered.

DESIGN

Perspective.

METHODS

Review and interpretation of selected literature, with perspective on the evaluation and management of patients with PAMM lesions. Multimodal imaging of 3 illustrative cases of PAMM are presented, including cross-sectional and en face optical coherence tomography (OCT), with progressive vascular occlusion and evidence of the ischemic cascade noted in 2 of the cases.

RESULTS

All 3 cases showed evidence of PAMM at baseline, including perivenular PAMM in 2 cases. Progression from a mild central retinal vein occlusion (CRVO) to a more severe CRVO was noted in the first case, while the second case progressed from an incomplete to complete central retinal artery occlusion (CRAO). In the third case, there was resolution of PAMM lesions associated with partial CRAO after the patient began taking aspirin.

CONCLUSIONS

Perivenular PAMM can be the only presenting sign of retinal vascular occlusion. In such cases, it is important to differentiate between partial CRVO and incomplete CRAO as the underlying cause. We provide guidance on making this important distinction, which plays a critical role in directing the nature and urgency of the systemic work-up. In patients with PAMM caused by partial retinal arterial occlusion, a benign empirical approach, such as low-dose aspirin (81 mg), may be reasonable to reduce the likelihood of subsequent vision loss from progression to complete arterial occlusion. A clinical trial, however, is necessary to support such a strategy.

Total venous nature of retinal deep capillary plexus inferred by continuity of prominent middle limiting membrane sign in optical coherence tomography

This study aimed to theoretically identify the vascular nature of the deep capillary plexus (DCP) by examining patients presenting with both paracentral acute middle maculopathy (PAMM) and prominent middle limiting membrane (p-MLM) sign and p-MLM sign alone in spectral-domain optical coherence tomography (SD-OCT). A retrospective review of the medical records of patients with retinal vein or artery occlusion from two tertiary medical centers was performed. Consecutive patients with a clinical diagnosis of all categories of retinal artery occlusion (RAO) and retinal vein occlusion (RVO) (branch or central and ischemic or non-ischemic) who had undergone SD-OCT imaging from January 2015 to May 2020 were recruited and their p-MLM signs and PAMM lesions were assessed. We included 118 patients who presented with p-MLM sign with or without PAMM lesions. Amon them, 40 were female and 78 were male, with a mean age of 61.1 years. Of the 109 patients with both p-MLM sign and PAMM lesions, 23 had branch RAO, two had branch RVO, 67 had central RAO, 13 had central RVO, and four had a combination of central RAO and central RVO. All nine patients with the p-MLM sign alone had central RVO accompanied by cystoid macular edema. In all the enrolled patients, the hyperreflective lines of the p-MLM sign were continuous, regardless of the type of PAMM lesions. In conclusion, when PAMM and p-MLM sign are examined together, further proof regarding the possible complete venous nature of the vasculature of the retinal DCP might be speculated.

[Acute diagnostics of central retinal artery occlusion and biomarkers of ischemia : Diagnostics with consequences?]

BACKGROUND

Acute central retinal artery occlusion (CRAO) represents an ophthalmological emergency with neurological implications, which must be immediately investigated and treated. Intravenous thrombolysis could improve the prognosis only within the first 4.5 h due to limited retinal tolerance to ischemia. Accordingly, ophthalmological acute diagnostics should be reduced to the minimum necessary followed by immediate referral to a clinic with neurovascular expertise. The typical anamnesis is well-suited for triaging and should be carried out ín a standardized way in order to determine the onset of symptoms as exactly as possible. In addition to pathognomic findings in fundoscopy, there are characteristic ischemia-related changes in optical coherence tomography (OCT), which document ischemia in the inner retina and under some circumstances can provide inferences for the onset of ischemia.

OBJECTIVE

This review article summarizes the acute ophthalmological diagnostic management of acute CRAO with a focus on the typical OCT and transorbital ultrasound (TOUS) findings and discusses their potential use as ischemic biomarkers.

CONCLUSION

Characteristic biomarkers make OCT an important diagnostic tool in the management of acute CRAO. Additional information can be obtained by TOUS. With an evidence-based treatment established in the future both tools could be used for indications for treatment and for estimating the prognosis.

Complications of Intra-Arterial tPA for Iatrogenic Branch Retinal Artery Occlusion: A Case Report through Multimodal Imaging and Literature Review

Background and Objectives: To document, through multimodal imaging, the post-procedural clinical course and visual outcome of a patient who received intra-arterial tissue plasminogen activator (tPA) for acute iatrogenic branch retinal artery occlusion (BRAO), and to review the literature and guidelines regarding the use of tPA for retinal arterial occlusions. Methods: A 28-year-old female patient who sustained an iatrogenic BRAO and subsequently received intra-arterial tPA was followed through her post-interventional course of 3 months with serial exams and multimodal imaging, including color fundus photography, visual field testing, spectral domain optical coherence tomography (SD-OCT), and OCT angiography (OCT-A). Results: A patient with history of left internal cerebral artery (ICA) aneurysm and baseline visual acuity (VA) of 20/20 developed an acutely symptomatic BRAO after undergoing a neuroendovascular procedure and was acutely treated with tPA through the left ophthalmic artery. At two weeks follow-up, a central posterior pole hemorrhage was noted although VA was preserved. A superior altitudinal defect was shown on automated perimetry. VA dropped to 20/50 at 7 weeks follow-up and hyperreflective material deep to the attachment between the posterior hyaloid and the internal limiting membrane (ILM) consistent with hemorrhage was noted on SD-OCT. At 11 weeks follow-up, VA returned to 20/20, SD-OCT revealed a membrane bridging the foveal depression, OCT-A showed decreased vascularity in the inferior macula, and the visual field defect was stable by automated perimetry. Conclusions: Intraocular hemorrhage is a possible complication of intra-arterial tPA administration for BRAO, and a careful analysis of risks, benefits, and goals of this procedure must be considered by both provider and patient before such intervention.

Cerebral angiographic features of central retinal artery occlusion patients treated with intra-arterial thrombolysis

BACKGROUND

Central retinal artery occlusion (CRAO) is an ischemic stroke of the eye. The atherosclerotic lesions in the intracranial segment of the carotid artery (CA) and the ophthalmic artery (OphA) are not well defined. We aimed to investigate the cerebral angiographic features of CRAO patients and assess the relationship between the angiographic features and outcomes after intra-arterial thrombolysis (IAT).

METHODS

We included 101 acute non-arteritic CRAO patients treated with IAT. We analyzed the detailed angiographic features of the OphA and ipsilateral CA, visual acuity, fundus photography, and fluorescein angiography.

RESULTS

Of the 101 patients, 38 patients (37.6%) had steno-occlusive lesions in the OphA, and 62 patients (61.4%) had atherosclerotic lesions in the ipsilateral CA. The patients with a higher degree of stenosis in the OphA showed a higher degree of stenosis (P=0.049) and a more severe morphology of plaque (P=0.000) in the ipsilateral CA. Additionally, although the visual outcome was not associated with these angiographic features, the lower degree of stenosis and less severe morphology of plaque in the ipsilateral CA resulted in a significant improvement in early reperfusion rate (P=0.018 and P=0.014, respectively) and arm-to-retina circulation (P=0.016 and P=0.002, respectively) of the eye after IAT.

CONCLUSIONS

There was a significant correlation in the severity of steno-occlusive lesions between the OphA and the ipsilateral CA in patients with CRAO. The patients with less severe angiographic features in the CA showed a more improved retinal reperfusion after IAT. The angiographic findings in the CA may serve as a predictive marker for the vessel integrity of the OphA and recanalization outcome after IAT.

[Update on intravenous lysis treatment : The REVISION trial]

BACKGROUND

To date, no evidence-based treatment for acute non-arteritic central retinal artery occlusion (CRAO) exists. Considering the limited ischemia tolerance of the retina and the results of multiple case series, increasing expectations are directed towards an early intravenous thrombolysis within 4.5 h after CRAO onset.

OBJECTIVE

The current literature regards timely retinal reperfusion as the only potentially beneficial therapeutic option to treat non-arteritic CRAO. Available data on the efficacy and safety of thrombolysis in CRAO are presented and discussed. On the basis of these data, the prospective, randomized, double-blind, placebo-controlled REVISION trial (early REperfusion therapy with intravenous alteplase for recovery of VISION in acute central retinal artery occlusion) will shortly be initiated in 25 centers across Germany in order to investigate early intravenous thrombolysis in acute CRAO. The main inclusion criteria of the REVISION trial are outlined, which may help ophthalmologists to identify study candidates and facilitate rapid referral to a study center.

CONCLUSION

The efficacy of intravenous thrombolysis in acute ischemic stroke is critically time dependent. This may also be assumed in acute CRAO; however, definite evidence still needs to be provided. Until then, the motto "time is retina" should be applied and intravenous thrombolysis should be offered to CRAO patients as part of randomized trials (such as REVISION). According to the current literature, other acute treatment approaches (such as paracentesis) are not indicated.

Thrombolysis for Central Retinal Artery Occlusion in 2020: Time Is Vision!

BACKGROUND

Acute nonarteritic central retinal artery occlusion (CRAO) is an eye stroke with poor visual prognosis and no proven effective therapies. Given advances in acute stroke care, thrombolysis in CRAO merits critical re-examination. We review the evidence for intravenous (IV) and intra-arterial (IA) tissue plasminogen activator (tPA) in CRAO management.

EVIDENCE ACQUISITION

MEDLINE, Scopus, and Cochrane online databases were systematically searched from 1960 to present, for reports of acute IV or IA therapy with alteplase or tenecteplase in nonarteritic CRAO patients. English language case reports, case series, interventional studies, or randomized controlled trials were included. The study type, age and number of subjects, the regimen administered, the time since symptoms' onset, visual outcome, and safety reports were noted.

RESULTS

Use of IV thrombolysis with alteplase was reported in 7 articles encompassing 111 patients, with 54% of them receiving IV tPA within 4.5 hours of symptom onset, and none developing symptomatic intracranial or ocular hemorrhage. Six studies described IA alteplase administration, with only 18 of a total of 134 patients (13.4%) treated within the first 6 hours after visual loss. The reported adverse events were minimal. Visual outcomes post-IV and IA thrombolysis were heterogeneously reported; however, most studies demonstrated benefit of the respective reperfusion therapies when administered very early. We found no reports of tenecteplase administration in CRAO.

CONCLUSIONS

In 2020, nonarteritic CRAO patients should theoretically receive the same thrombolytic therapies, in the same time window, as patients with acute cerebral ischemia. Eye stroke and teleeye stroke code encounters must include an expert ophthalmologic evaluation to confirm the correct diagnosis and to evaluate for ocular signs that may help guide IV tPA administration or IA management. Future research should focus on developing feasible retinal penumbra imaging studies that, similar to cerebral tissue viability or perfusion imaging, can be incorporated into the thrombolysis decision-making algorithm.

Clinical Characteristics of Paracentral Acute Middle Maculopathy in Eyes with Retinal Vascular Occlusion Diseases in Chinese Patients

Aim

To investigate the incidence and clinical characteristics of paracentral acute middle maculopathy (PAMM) and its relationship with prominent middle limiting membrane (p-MLM) sign in eyes with retinal artery occlusion (RAO) or retinal vein occlusion (RVO) in a Chinese clinical setting.

Methods

In this retrospective observational study from January 2015 to May 2020, multimodal imaging data of 807 eyes including 555 consecutive patients with RVO or 252 consecutive patients with RAO were reviewed. All patients were scanned using the spectrum-domain optical coherence tomography (OCT), and some of them underwent color fundus photography, fundus fluorescence angiography, en face OCT, and OCT angiography.

Results

PAMM was detected in 49 eyes of 49 RAO patients and 29 eyes of 29 RVO patients. The mean ages at presentation were 64.49 ± 13.90 years and 54.00 ± 18.48 years in RAO and RVO patients (P=0.006), respectively. Eyes with RAO were more prone to develop PAMM (19.44% [49/252] vs. 5.23% [29/555]; P < 0.001). Of the 78 eyes with PAMM, 24 eyes (7 eyes with RVO and 17 eyes with RAO) were found with p-MLM sign. An interesting phenomenon that had been overlooked before was that the hyperreflective line of the p-MLM sign was usually continuous, regardless of the type of PAMM lesion.

Conclusions

This series is the largest to date to describe the clinical characteristics of PAMM and p-MLM sign in Chinese patients. The incidence of PAMM and p-MLM sign in patients with RAO was relatively higher than that in patients with RVO. These signs alone probably represent milder ischemia and prompt us to carry out a comprehensive and meticulous examination to prevent the further development of the disease. In addition, the hyperreflective line of the p-MLM sign was usually continuous, which could support the totally venous nature of the retinal deep capillary plexus to some extent.

Spatial distribution of diabetic capillary non-perfusion

OBJECTIVE

To evaluate the distribution of capillary non-perfusion (CNP) in superficial and deep capillary plexuses (SCP and DCP) in eyes with diabetic retinopathy (DR).

METHODS

In this retrospective case series, macular optical coherence tomography angiography (OCTA) images were obtained from eyes with DR without diabetic macular edema (DME). The area of CNP in SCP and DCP was delineated using an automated approach after excluding the foveal avascular zone (FAZ) and major retinal vessels. The distribution and spatial correlation of the CNP in each layer were analyzed.

RESULTS

Forty-three eyes of 27 patients with DR with a mean age of 59.10 ± 9.05 years were included. The mean CNP area in SCP was statistically significantly higher than DCP (0.722 ± 0.437 mm² vs. 0.184 ± 0.145 mm² , respectively, p < .001). There was a statistically significant association between mean BCVA (0.28 ± 0.21 logMAR) and CNP area in DCP (p = .01). After automated subtraction of CNP areas in DCP from SCP, 25.43 ± 15.05% of CNP areas in the DCP had co-localized CNP areas in SCP. The CNP percentage was statistically significantly different between the concentric rings on foveal center, both in SCP and in DCP (both p < .001) showing a decreasing trend from the outer ring toward the center.

CONCLUSION

In DR, SCP is more ischemic than DCP. This is in contrast to the previously described oxygenation-dependent ischemic cascade following acute retinal vascular occlusions. This study provides further insight into the retinal ischemia in DR.

Structural and Functional Imaging of the Retina in Central Retinal Artery Occlusion - Current Approaches and Future Directions

Central retinal artery occlusion (CRAO) is a form of acute ischemic stroke which affects the retina. Intravenous thrombolysis is emerging as a compelling therapeutic approach. However, it is not known which patients may benefit from this therapy because there are no imaging modalities that adequately distinguish viable retina from irreversibly infarcted retina. The inner retina receives arterial supply from the central retinal artery and there is robust collateralization between this circulation and the outer retinal circulation, provided by the posterior ciliary circulation. Fundus photography can show canonical changes associated with CRAO including a cherry-red spot, arteriolar boxcarring and retinal pallor. Fluorescein angiography provides 2-dimensional imaging of the retinal circulation and can distinguish a complete from a partial CRAO as well as central versus peripheral retinal non-perfusion. Transorbital ultrasonography may assay flow through the central retinal artery and is useful in the exclusion of other orbital pathology that can mimic CRAO. Optical coherence tomography provides structural information on the different layers of the retina and exploratory work has described its utility in determining the time since onset of ischemia. Two experimental techniques are discussed. 1) Retinal functional imaging permits generation of capillary perfusion maps and can assay retinal oxygenation and blood flow velocity. 2) Photoacoustic imaging combines the principles of optical excitation and ultrasonic detection and - in animal studies - has been used to determine the retinal oxygen metabolic rate. Future techniques to determine retinal viability in clinical practice will require rapid, easily used, and reproducible methods that can be deployed in the emergency setting.

Widefield en face optical coherence tomography monitoring of the peri-venular fern-like pattern of paracentral acute middle maculopathy

Purpose

To demonstrate the ability of widefield en face swept source optical coherence tomography (OCT) imaging to monitor peri-venular fern-like patterns of paracentral acute middle maculopathy (PAMM) associated with retinal arterial occlusions.

Observations

The peri-venular fern-like pattern of PAMM was diagnosed on the 12 × 12 mm en face structural OCT images from three patients. Fluorescein angiography images were unremarkable. Over time, all three patients demonstrated significant improvement in visual acuity with resolution of their peri-venular PAMM.

Conclusions

The peri-venular fern-like pattern of PAMM is usually associated with retinal vein occlusions, but we identified three cases with this pattern in eyes with presumed incomplete retinal arterial occlusions. Our cases support the ischemic cascade theory that begins within the deep capillary plexus and ascends in the retina depending on the severity of the ischemic event. Using the 12 × 12 mm en face structural OCT images, we are able to demonstrate a wider area of ischemia in PAMM compared with the traditional 6 × 6 mm scans.

Optical coherence tomography-based determination of ischaemia onset - the temporal dynamics of retinal thickness increase in acute central retinal artery occlusion

PURPOSE

Acute central retinal artery occlusion (CRAO) induces ischaemic retinal oedema. The purpose of this study was to define sensitivity and specificity of optical coherence tomography (OCT) based retinal thickness analysis in determining ischaemia onset in CRAO.

METHODS

The relative retinal thickness increase (RRTI) in comparison with the fellow eye was analysed retrospectively in OCT scans of 66 patients diagnosed with CRAO between January 2010 and December 2019 within 48 hr of ischaemia onset. The natural course of RRTI and the sensitivity and specificity of OCT-based determination of ischaemia onset in identifying CRAO within 4.5 hr using the RRTI were evaluated.

RESULTS

Relative retinal thickness increase (RRTI) in acute CRAO follows a hyperbolic curve with a steep incline within the early phase after which it reaches a plateau. Optical coherence tomography (OCT)-based retinal thickness analysis in CRAO allows to differentiate patients with ischaemia onset within the past 4.5 hr or thereafter with a sensitivity of 100% and a specificity of 94.3%.

CONCLUSION

Relative retinal thickness increase (RRTI) allows to identify CRAO patients that are eligible for a potentially beneficial reperfusion therapy within a therapeutic window of 4.5 hr with a high accuracy. Especially in patients with unknown ischaemia onset, this diagnostic tool could be of major importance in the future clinical management.

Multimodal imaging for paracentral acute maculopathy; the diagnostic role of en face OCT

Background

To describe the features of multimodal imaging and the diagnostic role of en face OCT in the paracentral acute middle maculopathy (PAMM) spectrum.

Methods

In this observational case series, 5 eyes of 5 patients with acute PAMM were identified. Demographic characteristics as well as data regarding the underlying disease, presenting visual acuity (VA) and ophthalmic examination results were recorded. All patients underwent multimodal imaging within 3 days after symptom onset.

Results

The mean age of patients was 52.2 (range, 33–67) years. Systemic comorbidities including diabetes mellitus and hypertension were identified in two patients. Except for one patient diagnosed with isolated PAMM, other patients had signs of retinal vascular disease such as a cilioretinal artery or branch retinal artery obstruction, non-ischemic central retinal vein occlusion, or a combination of these vascular disorders. The central vision was preserved in two cases; however, the remaining cases presented with profound VA reduction. Different patterns of PAMM including arterial, globular, and fern-like were observed in en face OCT at deep capillary plexus (DCP) level. En face OCT images could precisely delineate the margin of the PAMM area. Optical coherence tomography angiography (OCTA) showed decreased vascular density in DCP. Unresolved projection artifact by conventional OCTA software was observed in DCP and choriocapillaris slabs in all cases.

Conclusion

En face structural OCT in PAMM can delineate the area of ischemia and the degree of foveal involvement. Unresolved projection artifact by conventional OCTA software in the PAMM area can be seen in DCP and choriocapillaris layers.

Central retinal artery occlusion as a neuro-ophthalmological emergency: the need to raise public awareness

BACKGROUND AND PURPOSE

Central retinal artery occlusion (CRAO) is a neuro-ophthalmological emergency necessitating adequate and comprehensive diagnosis. Its optimal management and treatment, however, are still under debate. This study aimed at identifying respective areas for improvement.

METHODS

We retrospectively analysed the medical records of patients with CRAO treated in our stroke unit between January 2016 and August 2020.

RESULTS

During the observational period, 101 patients with CRAO were admitted. We observed an increase in the rate of patients primarily admitted to the stroke unit from 52.2% to 97.4%. In addition, the thrombolysis rate - with thrombolysis performed on an individual basis - rose from 0% to 14.1%, coinciding with the implementation of an in-hospital management guideline. Almost 60% of all patients presented outside of the 4.5-h time window for thrombolysis; by far the most common reason not to deliver intravenous thrombolysis in our cohort was a prehospital delay to presentation (58.8%), with 44.4% of patients having consulted a private-practice ophthalmologist first. A total of 25 (32.5%) of 77 patients who underwent magnetic resonance imaging (MRI) had accompanying acute ischaemic stroke lesions on diffusion-weighted MRI of the brain. A possible aetiology of CRAO was identified in 41.4% of patients.

DISCUSSION

Public awareness of sudden unilateral visual loss as a presenting sign for stroke should be raised, increasing the chances for timely recognition in a hospital with ophthalmological expertise and a stroke centre. This is essential for ongoing and future prospective trials on this subject.

Efficacy of YAG Laser Embolysis in Retinal Artery Occlusion

Objective:

To compare the anatomical and functional success between conventional medical method and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser embolysis in retinal artery occlusion.

Methods:

This randomized control trial was conducted at Armed Forces Institute of Ophthalmology (AFIO) Rawalpindi from July 2018 to May 2020. A total of 14 eyes of 14 patients were received with fovea involving branch or hemiretinal artery occlusion within 24 hours of onset of symptoms. They were divided randomly in two groups. Initial treatment was given to all cases, and seven eyes received Nd:YAG laser treatment for embolysis. Both groups were analysed for anatomical success (reperfusion) and functional success (defined as improvement in visual acuity to better than 6/60 on Snellen’s visual acuity chart from baseline visual acuity).

Results:

In conventional group, anatomical success was achieved in 2 (28.6%) eyes, while significant visual improvement was seen in 3 (42.8%) eyes. In Nd:YAG laser embolysis group, anatomical success was achieved in 5 (71.4%) eyes, while significant visual improvement was seen in 6 (85.7%) eyes. All eyes which showed functional improvement underwent Nd:YAG laser embolysis within 6 hours of onset of symptoms.

Conclusions:

Nd: YAG laser embolysis is more effective in management of fovea threatening retinal artery occlusion, as compared to conventional medical treatment, if performed within six hours of onset of symptoms.

Suspended scattering particles in motion using OCT angiography in branch retinal vein occlusion disease cases with cystoid macular edema

We aimed to investigate the clinical implication of suspended scattering particles in motion (SSPiM) using optical coherence tomography angiography (OCTA) among branch retinal vein occlusion disease (BRVO) cases with macular edema (ME). Medical records of BRVO patients were reviewed. Central retinal thickness (CRT), ME type, and cyst size on optical coherence tomography images were evaluated before and after intravitreal bevacizumab injection. Nonperfusion area, SSPiM, and microvascular abnormalities in OCTA images were evaluated using a Heidelberg machine. SSPiM was identified in 24 of 56 cases. There were no differences in baseline characteristics between groups with and without SSPiM. Disease duration, disease-free duration, previous injection number, microaneurysms in the superficial vascular complex, and microaneurysms in the deep vascular complex (DVC) (p = 0.003, 0.013, 0.028, 0.003, < 0.001, respectively) differed significantly between the two groups. After multivariate logistic analysis, microaneurysms in the DVC were the only different factor between the two groups (odds ratio [OR]: 0.091; p = 0.001). Furthermore, SSPiM in the DVC (OR 10.908; p = 0.002) and nonperfusion grade (OR 0.039; p < 0.001) were significantly associated with cyst response after intravitreal injection. SSPiM may be correlated with microaneurysms in the DVC and a poor anatomical response after intravitreal injection.

Paracentral acute middle maculopathy and the organization of the retinal capillary plexuses

The retinal capillary vasculature serves the formidable role of supplying the metabolically active inner and middle retina. In the parafoveal region, the retinal capillary plexuses (RCP) are organized in a system of three capillary layers of varying retinal depths: the superficial capillary plexus (SCP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP). While the dynamic flow through these plexuses is complex and not completely understood, current research points to a hybrid model that includes both parallel and in series components in which blood flows in a predominantly serial direction between the superficial vascular complex (SVC) and deep vascular complex (DVC). Each capillary plexus autoregulates independently, so that under most conditions the retinal vasculature supplies adequate blood flow and oxygen saturation at varying depths despite diverse environmental stressors. When the flow in the deep vascular complex (i.e. ICP and DCP) fails, an ischemic lesion referred to as Paracentral Acute Middle Maculopathy (PAMM) can be identified. PAMM is an optical coherence tomography (OCT) finding defined by the presence of a hyperreflective band at the level of the inner nuclear layer (INL) that indicates INL infarction caused by globally impaired perfusion through the retinal capillary system leading to hypoperfusion of the DVC or specifically the DCP. Patients present with an acute onset paracentral scotoma and typically experience a permanent visual defect. Lesions can be caused by a diverse set of local retinal vascular diseases and systemic disorders. PAMM is a manifestation of the retinal ischemic cascade in which the mildest forms of ischemia develop at the venular end of the DCP, i.e. perivenular PAMM, while more severe forms progress horizontally to diffusely involve the INL, and the most severe forms progress vertically to infarct the inner retina. Management is targeted toward the identification and treatment of related vasculopathic and systemic risk factors.

Correlation of electroretinography components with visual function and prognosis of central retinal artery occlusion

We investigated the full-field electroretinographic (ERG) parameters with visual function and prognosis in central retinal artery occlusion (CRAO), according to its severity. 110 affected eyes of CRAO patients were enrolled and compared with fellow uninvolved eyes (N = 110) and normal control eyes (N = 30). B/A ratio and photopic negative response amplitude (PhNR) resulted in statistically significant differences among the CRAO subgroups according to the severity of retinal ischemia. Amplitudes of PhNR indicating ganglion cell function showed a more marked decline in mild to severe ischemia than those of the B-wave. In terms of visual function and outcome, baseline visual acuity and visual field defects were correlated with B/A ratio only (both, P < .001), whereas improvements in visual acuity and visual field were correlated with B-wave amplitude in dark-adapted 3.0 (P = .004 and .006), B/A ratio (P = .023 and .008), and PhNR amplitude (P < .001 and .004). These three ERG parameters were found to be credible predictive factors of visual prognosis. In conclusion, B-wave amplitude in dark-adapted 3.0, B/A ratio, and PhNR amplitude changes in eyes with CRAO are associated with baseline features related to the severity of retinal ischemia, and these are correlated with visual function and prognosis.

Paracentral acute middle maculopathy-review of the literature

Paracentral acute middle maculopathy (PAMM) is a recently identified spectral-domain optical coherence tomography (SD-OCT) finding characterized by a hyper-reflective band spanning the inner nuclear layer (INL), which typically evolves to INL atrophy in later stages. Typical clinical features include the sudden onset of one or multiple paracentral scotomas, normal or mild reduction in visual acuity, and a normal fundus appearance or a fundus with a deep grayish lesion. Although its pathophysiology is not yet fully understood, ischemia at the level of the intermediate and deep capillary plexa has been demonstrated to play a major role. Since its first description, an increasing number of publications on PAMM have been published in ophthalmology scientific journals. The purpose of this study is to provide a review of the current literature on PAMM.

Retinal Oxygen Delivery, Metabolism, and Extraction Fraction during Long-Term Bilateral Common Carotid Artery Occlusion in Rats

Retinal functional, biochemical, and anatomical changes have been previously reported in long-term experimental permanent bilateral common carotid artery occlusion (BCCAO). The purpose of the current study was to investigate progressive reductions in retinal oxygen metabolism (MO₂) due to inadequate compensation by oxygen delivery (DO₂) and extraction fraction (OEF) after BCCAO. Twenty-nine rats were subjected to BCCAO and were imaged after 3 hours, 3 days, 7 days, or 14 days. Six rats underwent a sham procedure. Phosphorescence lifetime and blood flow imaging were performed in both eyes to measure retinal oxygen contents and total retinal blood flow, respectively. DO₂, MO₂, and OEF were calculated from these measurements. Compared to the sham group, DO₂ and MO₂ were reduced after all BCCAO durations. OEF was increased after 3 hours and 3 days of BCCAO, but was not different from the sham group after 7 and 14 days. Between 3 and 7 days of BCCAO, DO₂ increased, OEF decreased, and there was no significant difference in MO₂. These findings may be useful to understand the pathophysiology of retinal ischemia.

Paracentral Acute Middle Maculopathy as a Presenting Sign of CRAO in Sickle Cell Disease Treated with Tissue Plasminogen Activator

PURPOSE

We report the case of a 27-year-old monocular woman with history of sickle cell disease who received intra-arterial tissue plasminogen activator (tPA) after presenting with acute painless vision loss secondary to incomplete central retinal artery occlusion presenting as paracentral acute middle maculopathy (PAMM) in her left eye.

METHODS

Ultra-widefield fundus photography, ultra-widefield fluorescein angiography, en face ocular coherence tomography (OCT), and ocular coherence tomography angiography (OCTA) were obtained and reviewed, followed by cerebral angiography and infusion of intra-arterial tissue plasminogen activator (tPA).

RESULTS

A patient with a history of sickle cell disease presented with new onset of a dense central scotoma and visual acuity diminished to 20/200 from baseline 20/20 in her left eye. Fluorescein angiogram was non-diagnostic. OCT revealed perifoveal hyperreflective bands in the inner nuclear layer in a pattern characteristic of PAMM. The patient received intra-arterial tPA through her left ophthalmic artery shortly after presentation, resulting in a gradual restoration of visual acuity to 20/20 in the three months following the procedure.

CONCLUSIONS

This is the first report describing the use of intra-arterial tPA to treat incomplete central retinal artery occlusion presenting as a PAMM lesion in a patient with sickle cell disease.

Normal to supernormal 30-Hz flicker ERGs predict visual function and prognosis in central retinal artery occlusion

PURPOSE

To determine whether normal to supernormal 30-Hz flicker ERGs are associated with visual function and prognosis in patients with central retinal artery occlusion (CRAO).

METHODS

A total of 133 patients diagnosed with unilateral acute non-arteritic CRAO by examination with electroretinography (ERG) were examined. Thirty-hertz flicker ERG amplitudes were analyzed according to the severity of CRAO, and their correlation with visual function and prognosis was assessed. All patients were categorized into one of three groups according to the flicker ERG amplitude ratios between affected and fellow eyes: ≥ 110%, supernormal; 90-110%, normal; and < 90%, subnormal.

RESULTS

Thirty-hertz flicker ERG parameters differed significantly according to the severity of retinal ischemia, i.e., between incomplete versus complete CRAO: mean amplitude (55.89 ± 24.38 > 45.41 ± 23.47 μV, P = 0.029), amplitude ratio (76.1 ± 23.1% > 58.7 ± 25.7%, P < 0.001), and proportion of normal to supernormal flicker ERGs (30.5% > 12.4%, P < .001). One-month and final follow-up visual function and prognosis were better in the normal to supernormal flicker ERGs: 1 month BCVA (1.55 ± 0.65 > 2.05 ± 0.61 logMAR, P < .001), final BCVA (1.32 ± 0.79 > 1.97 ± 0.68 logMAR, P < .001), 1-month VA improvement (- 0.50 ± 0.47 > - 0.10 ± 0.29 logMAR, P < .001), and final VA improvement (- 0.74 ± 0.61 > - 0.18 ± 0.37 logMAR, P < .001).

CONCLUSIONS

Normal to supernormal 30-Hz flicker ERG changes in eyes with CRAO are associated with the milder severity of retinal ischemia and showed better visual function and outcome than the subnormal ERG group.

Relation of Retinal Oxygen Measures to Electrophysiology and Survival Indicators after Permanent, Incomplete Ischemia in Rats

Studies in experimental ischemia models by permanent bilateral common carotid artery occlusion (BCCAO) have reported reduced retinal electrophysiological function, coupled with inner retinal degeneration and gliosis. In the current study, we tested the hypothesis that long-term (up to 14 days) BCCAO impairs oxygen delivery (DO₂), which affects oxygen metabolism (MO₂) and extraction fraction (OEF), electrophysiological function, morphology, and biochemical pathways. Twenty-one rats underwent BCCAO (N = 12) or sham surgery (N = 9) and were evaluated in separate groups after 3, 7, or 14 days. Electroretinography (ERG), optical coherence tomography, blood flow and vascular oxygen tension imaging, and morphological and biochemical evaluations were performed in both eyes. Reduced ERG b-wave amplitudes and delayed implicit times were reported at 3, 7, and 14 days following BCCAO. Total retinal blood flow, MO₂, and DO₂ were reduced in all BCCAO groups. OEF was increased in both 3- and 7-day groups, while no significant difference was observed in OEF at 14 days compared to the sham group. At 14 days following BCCAO, total and inner retinal layer thickness was reduced, while the outer nuclear layer thickness and gliosis were increased. There was an increase in nuclei containing fragmented DNA at 3 days following BCCAO. The compensatory elevation in OEF following BCCAO did not meet the tissue demand, resulting in the subsequent reduction of MO₂. The associations between retinal MO₂, DO₂, and retinal function were shown to be significant in the sequelae of persistent ischemia. In sum, measurements of DO₂, MO₂, and OEF may become useful for characterizing salvageable tissue in vision-threatening pathologies.

Iatrogenic ophthalmic artery occlusion and retinal artery occlusion

Iatrogenic ophthalmic artery occlusion (IOAO) is a rare but devastating ophthalmic disease that may cause sudden and permanent visual loss. Understanding the possible etiologic modalities and pathogenic mechanisms of IOAO may prevent its occurrence. There are numerous medical etiologies of IOAO, including cosmetic facial filler injection, intravascular procedures, intravitreal gas or drug injection, retrobulbar anesthesia, intraarterial chemotherapy in retinoblastoma. Non-ocular surgeries and vascular events in arteries that are not directly associated with the ophthalmic artery, can also cause IOAO. Since IOAO has a limited number of treatment modalities, which lead to poor final visual prognosis, it is imperative to acknowledge the information regarding medical procedures that are etiologically associated with IOAO. We accumulated all searchable and available IOAO case reports (our cases and previous reported cases from the literature), classified them according to their mechanisms of pathogenesis, and summarized treatment options and responses of each of the causes. Various sporadic cases of IOAO can be categorized into three mechanisms as follows: intravascular event, orbital compartment syndrome, and increased intraocular pressure. Embolic IOAO, which is considered the primary cause of the condition, was classified into three subgroups according to the pathway of embolic movement (retrograde pathway, anterograde pathway, pathway through collateral channels). Despite the practical limitations of treating spontaneous (non-iatrogenic) retinal artery occlusion, this article will contribute in predicting and improving the prognosis of IOAO by recognizing the treatable factors. Furthermore, it is expected to provide clues to future research associated with the treatment of retinal artery occlusion.

Safety and effectiveness of a novel neuroprotectant, KUS121, in patients with non-arteritic central retinal artery occlusion: An open-label, non-randomized, first-in-humans, phase 1/2 trial

Kyoto University Substance (KUS) 121, an ATPase inhibitor of valosin-containing protein, is a novel neuroprotectant. We tested the safety and effectiveness of KUS121 in patients with acute central retinal artery occlusion (CRAO). We conducted an investigator-initiated, first-in-humans, phase 1/2 clinical trial. Nine patients with non-arteritic CRAO symptoms lasting for 4–48 h were enrolled. These patients received daily intravitreal injections of KUS121 for 3 days: 25 μg (low-dose) in the first three patients and 50 μg (high-dose) in the next six patients. The primary endpoint was the safety of the drug. As a secondary endpoint, pharmacokinetics was evaluated. Other key secondary endpoints were changes in best-corrected visual acuity (BCVA), measured using the Early Treatment Diabetic Retinopathy Study chart, visual field scores, and retinal sensitivities between baseline and week 12; and decimal BCVA at week 12. Administration of KUS121 did not result in serious adverse events. All nine patients (100%) showed significant improvement of BCVA. Average readable letter counts, visual field scores, and retinal sensitivities also improved. Decimal BCVA at week 12 was better than 0.1 in four patients (44%) and equal to or better than 0.05 in seven patients (78%). This first-in-humans clinical trial provides support for the safety and efficacy of intravitreal KUS121 injection. To substantiate the safety and effectiveness for patients with acute CRAO, further larger scale clinical studies will be needed.

Development of visual acuity under hyperbaric oxygen treatment (HBO) in non arteritic retinal branch artery occlusion

PURPOSE

Nonperfusion of retinal tissue due to arterial occlusion leads inevitably to mostly irreversible retinal damage. Until today no evidence-based treatment exists. Inhalation of 100% oxygen at high atmospheric pressure causes an increased solubility of oxygen in the blood that helps the retinal tissue to survive through diffusion in case of an artery occlusion till vascular recanalization occurs. Hence the purpose of this study is to compare the visual outcome in patients with retinal branch artery obstruction treated with hyperbaric oxygen versus patients treated with hemodilution only.

METHODS

Non-randomized, monocentric, retrospective study. Patients with diagnosis of non-arteritic retinal branch artery occlusion (BRAO) treated with hyperbaric oxygen therapy between 1997 and 2017. Exclusion criteria were central retinal artery occlusion, presence of a cilioretinal artery and arteritic cases. The control group was matched based on visual acuity (VA) at admission, age, and delay between symptoms and beginning of clinical care.

RESULTS

The control group and the matching oxygen group contained 14 patients each. Initial VA in the matched HBO group was 0.18 ± 0.19 and 0.23 ± 0.19 in the control group (p = 0.57). Final VA at discharge was 0.69 ± 0.29 in the matched oxygen group and 0.32 ± 0.23 in the control group (p = 0.0009). HBO-treated patients had a significant visual increase compared with the control group. The most common comorbidities were arterial hypertension and vascular sclerosis.

CONCLUSION

HBO treatment appears to have a beneficial effect on visual outcome in patients with retinal branch artery occlusion. HBO treatment could be a rescue therapy at an early stage of BRAO, especially to bridge the time of a potential reperfusion. However, further, prospective, randomized clinical trials are required to verify this assumption.

Association of Optical Coherence Tomography Angiography of Collaterals in Retinal Vein Occlusion With Major Venous Outflow Through the Deep Vascular Complex

Importance

Analysis of collateral vessel formation following retinal vein occlusion may advance our understanding of the venous outflow anatomy in the macula.

Objective

To determine the location of collateral vessels with optical coherence tomography (OCT) angiography imaging.

Design, Setting, and Participants

Observational retrospective cohort study. Collateral vessel formation was studied with OCT angiography (OCTA) in patients with retinal vein occlusion (RVO). The study took place at 2 retinal practices (Vitreous Retina Macula Consultants of New York and Stein Eye Institute, University of California, Los Angeles), with patient records retrieved from March 2015 to August 2017. Data analysis was completed in November 2017.

Exposures

Collaterals identified with fundus photography and/or fluorescein angiography were analyzed with OCTA to determine their course through the superficial vascular plexus (SVP) and the deep vascular complex (DVC).

Main Outcomes and Measures

Collateral vessel pathways through the SVP and DVC were analyzed with cross-sectional and en face OCT and OCTA segmentation and color-coded volume renderings prepared from raw OCTA voxel data.

Results

From 23 eyes (22 branch and 1 hemispheric retinal vein occlusion ) of 23 patients (mean [SD] age, 73 [11] years), 101 collateral vessels were identified and analyzed (mean [SD], 4.4 [2.0]; range, 2-9 collateral per eye). On OCTA, the collaterals appeared as curvilinear dilated flow signals that connected veins across the horizontal raphe or veins on opposite sides of an occluded venous segment within the same retinal hemisphere. Of the 101 collaterals analyzed, all showed greater flow signal in the DVC, and all had some portion of their course identified within the DVC. No collaterals were found exclusively in the SVP. Volume renderings for 3 cases confirmed qualitatively that retinal collateral vessels course through the retina predominantly at the level of the DVC.

Conclusions and Relevance

Based on a limited number of cases, all collateral vessels associated with retinal vein occlusion were found to course through the DVC. The absence of collaterals isolated to the SVP supports a serial arrangement of the SVP and DVC, with venous drainage predominantly coursing through the DVC.

Misery Perfusion, Diffusive Oxygen Shunting and Interarterial Watershed Infarction Underlie Oxygenation-Based Hypoperfusion Maculopathy

PURPOSE

To describe and explain the entire range of acute ischemic macular damage that follows panretinal hypoperfusion from central retinal artery or vein occlusion.

DESIGN

Perspective article.

METHODS

To correlate the fundoscopic, fluorescein angiographic, oximetric, and optical coherence tomographic (OCT) features developing within the posterior inner retina following incremental reductions in arteriovenous perfusion pressure across the retinal circulation.

RESULTS

The spectrum of acute oxygenation-based hypoperfusion maculopathy (OHM) is consistent with that predictable from a modified Krogh cylinder model of tissue oxygenation. Diffusive oxygen shunting plays a significant role in the "artery-dominated" generation of ischemic signs during misery perfusion. Three major grades of OHM severity can be discerned according to the predominant oxygenation status of ganglion cells within the superficial inner retina, whether this is normoxic (OHM1), hypoxic (OHM2), or anoxic (OHM3). Densely opaque axoplasmic sentinels are arranged along normoxic/hypoxic interfaces in OHM2. In OHM1 and OHM2, relative hypermetabolism and interarterial watershed infarction of fundal interneurons (WIFI) underpin subtle middle-retinal opacification with periarterial sparing. The fundal signs are optimally displayed en face using autofluorescence imaging whereas cross-sectional OCT reveals Paques' plaque formation.

CONCLUSIONS

An exquisite and supremely accessible exhibition of classical oxygen physiopathology unfolds in eyes with panretinal hypoperfusion courtesy of the transparent ocular media and the pattern of macular neuroretinal opacification that evolves as upstream tissues extract oxygen to the detriment of tissues downstream. Recent attempts to overrule the simple conceptual framework embodied in WIFI have no plausible anatomical nor physiological basis. Overreliance on OCT can result in misdiagnosis.

Animal Models Used to Simulate Retinal Artery Occlusion: A Comprehensive Review

Purpose

To present an overview of animal models of retinal artery occlusion (RAO).

Methods

Through a systematic literature search in PubMed and Embase, papers describing methods of inducing RAO in animal models were included. The identified methodologic approaches were presented in a narrative synthesis and compared with RAO in humans.

Results

In total, 83 papers reporting on 88 experiments were included. Six different species were used with rodents and monkeys being the most common, and a minority were performed using cats, dogs, rabbits, or pigs. The anatomy of pigs and monkeys resemble that of humans most closely. The two most frequently used methods were laser-induced occlusion or ligation of the arteries. Other methods included raised intraocular pressure, arterial clamping, administration of vasoconstricting agents, the use of an occluder, embolization, and endovascular approaches to induce occlusion. In general, occlusions lasted for only 30 to 90 minutes, often followed by reperfusion.

Conclusions

Although a broad range of methods have previously been used, they all have limitations. Preferably, the methods should imitate the human disease as closely as possible and avoid damaging other structures. Therefore, monkeys followed by pigs are to be preferred and ligation or clamping may be a suitable model in larger animals as there is a potential to isolate and occlude the retinal artery only. Being less invasive, laser-induced occlusion is another suitable approach.

Translational Relevance

This review aims at assisting researchers in deciding on the most ideal experimental setting, and thereby increase the translational value to human disease.

Marine-Steroid Derivative 5α-Androst-3β, 5α, 6β-triol Protects Retinal Ganglion Cells from Ischemia⁻Reperfusion Injury by Activating Nrf2 Pathway

High intraocular pressure (IOP)-induced retinal ischemia leads to acute glaucoma, which is one of the leading causes of irreversible visual-field loss, characterized by loss of retinal ganglion cells (RGCs) and axonal injury in optic nerves (ONs). Oxidative stress and the inflammatory response play an important role in the ischemic injury of retinal and optic nerves. We focus on 5α-androst-3β, 5α, 6β-triol (TRIOL), a synthetic neuroactive derivative of natural marine steroids 24-methylene-cholest-3β, 5α, 6β, 19-tetrol and cholestane-3β, 5α, 6β-triol, which are two neuroactive polyhydroxysterols isolated from the soft coral Nephthea brassica and the gorgonian Menella kanisa, respectively. We previously demonstrated that TRIOL was a neuroprotective steroid with anti-inflammatory and antioxidative activities. However, the potential role of TRIOL on acute glaucoma and its underlying mechanisms remains unclear. Here, we report TRIOL as a promising neuroprotectant that can protect RGCs and their axons/dendrites from ischemic-reperfusion (I/R) injury in an acute intraocular hypertension (AIH) model. Intravitreal injection of TRIOL significantly alleviated the loss of RGCs and the damage of axons and dendrites in rats and mice with acute glaucoma. As NF-E2-related factor 2 (Nrf2) is one of the most critical regulators in oxidative and inflammatory injury, we further evaluated the effect of TRIOL on Nrf2 knockout mice, and the neuroprotective role of TRIOL on retinal ischemia was not observed in Nrf2 knockout mice, indicating that activation of Nrf2 is responsible for the neuroprotection of TRIOL. Further experiments demonstrated that TRIOL can activate and upregulate Nrf2, along with its downstream hemeoxygenase-1 (HO-1), by negative regulation of Kelch-like ECH (Enoyl-CoA Hydratase) associated Protein-1 (Keap1). In conclusion, our study shed new light on the neuroprotective therapy of retinal ischemia and proposed a promising marine drug candidate, TRIOL, for the therapeutics of acute glaucoma.

Central retinal artery occlusion-A new, provisional treatment approach

The retinal ganglion cells infarcted in central retinal artery occlusion (CRAO) are the somata of the optic nerve axons, part of the central nervous system. Consequently, CRAO with inner retinal infarction is a small vessel stroke, usually with the devastating consequence of severe visual loss in the affected eye. At present, there is no generally accepted, evidence-based therapy of nonarteritic CRAO in contrast to ischemic cerebral stroke that has well-accepted treatment protocols. Widely divergent and controversial therapeutic options for CRAO reflect the desperation of treating physicians and disparate conflicting studies. We examine reasons why treatment of nonarteritic CRAO remains problematic and then suggest a provisional new approach to treatment based on updated understanding of CRAO pathophysiology and analysis of current therapeutic options and their rationales.

Visual field defects and changes in central retinal artery occlusion

Objectives

To investigate the characteristics and temporal changes in visual field defects (VFDs) in eyes with acute central retinal artery occlusion (CRAO).

Design

Retrospective, observational case series

Methods

A total of 119 patients diagnosed with acute non-arteritic CRAO through examination with Goldmann perimetry were included among the patients who visited Seoul National University Bundang Hospital between January 2009 and December 2016. They were treated with either conservative treatments or intra-arterial thrombolysis (IAT). The baseline features and temporal changes of visual field examination results and the association with clinical parameters including visual acuity, optical coherence tomography (OCT) findings, and the CRAO stages.

Results

All of the 119 patients showed visual field defect and suffered unilateral acute CRAO. We observed five characteristic VFDs: peripheral constriction only (8%), paracentral scotoma (3%), central and cecocentral scotoma (19%), temporal island (59%), and no visual field (10%). Severe VFDs were associated with severe CRAO stages, poor baseline BCVA, delayed retinal arterial perfusion, and severe retinal morphologic changes on OCT. We found improvements in the visual field in 39% of all cases during the follow-up periods. Mild CRAO stages, good baseline BCVA, mild retinal morphologic changes, and mild initial VFDs were significantly associated with visual field improvement.

Conclusions

The five characteristic types of VFDs and their improvement in eyes with CRAO are associated with baseline features related to the severity of retinal ischemia. We suggest that the underlying mechanisms of VFDs involve the balance between the retinal arterial perfusion and the ischemic vulnerability of each retinal area.

Paracentral Acute Middle Maculopathy and the Ischemic Cascade Associated With Retinal Vascular Occlusion

PURPOSE

To analyze the spectrum of ischemia associated with paracentral acute middle maculopathy (PAMM) in eyes with acute retinal vascular occlusion and to describe an ischemic cascade.

DESIGN

A retrospective observational case series.

METHODS

Patients presenting with PAMM secondary to acute retinal vascular occlusion were identified. Analysis of multimodal imaging was performed at baseline and at follow-up visits to elucidate the patterns and progression of ischemia within the retinal layers.

RESULTS

Multimodal retinal imaging from 16 eyes of 16 patients with acute retinal vascular occlusion associated with PAMM was studied. Analysis of en face optical coherence tomography (OCT) segmentation of the inner nuclear layer (INL) identified distinct patterns of PAMM correlating with the severity of ischemia and not the type of occlusion. A perivenular fern-like PAMM pattern was associated with better visual outcomes (average final visual acuity was 20/25). This pattern was noted to sequentially progress in 2 cases to a diffuse globular PAMM pattern in the INL, or to a pattern of ischemia involving both the middle and inner retinal layers with commensurate vision loss. Globular patterns of PAMM or ischemia involving both the middle and inner retina correlated with poorer visual outcomes (average final visual acuity was counting fingers at 5.5 ft). These various patterns of ischemia developed in eyes with retinal vascular occlusions in which blood flow through the retinal capillary plexuses was present but was significantly reduced and delayed.

CONCLUSIONS

This study describes OCT findings suggestive of an ischemic cascade in eyes with retinal vascular occlusion. The middle retina at the level of the deep capillary plexus, especially at the venular pole, may be more vulnerable to ischemic injury.

PARACENTRAL ACUTE MIDDLE MACULOPATHY IN A PERIVENULAR FERN-LIKE DISTRIBUTION WITH EN FACE OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To report a case of central retinal vein occlusion resulting in a perivenular pattern of paracentral acute middle maculopathy lesions best identified with en face optical coherence tomography (OCT).

METHODS

Retrospective case report. Optos ultra-widefield fluorescein angiography, spectral domain OCT, en face OCT, and OCT angiography were performed.

RESULTS

A 41-year-old man presented with decreased vision in the right eye for 2 weeks. Funduscopic examination of the affected right eye was notable for subtle retinal whitening in the macula, mild retinal venous dilation and tortuosity, and few scattered retinal dot and blot hemorrhages consistent with an acute central retinal vein occlusion. Widefield fluorescein angiography demonstrated delayed arterial and venous filling but no evidence of significant peripheral retinal vascular ischemia. En face OCT segmented at the inner nuclear layer illustrated a remarkable and precise perivenular distribution of fern-like paracentral acute middle maculopathy with periarterial sparing, whereas en face OCT segmented at the outer nuclear layer demonstrated florid cystoid macular edema. At 6-week follow-up, OCT demonstrated patchy areas of atrophic inner nuclear layer and spontaneous resolution of the cystoid macular edema. Optical coherence tomography angiography at the level of the deep capillary plexus illustrated remarkable flow reduction of the deep capillary plexus in mainly a perivenular distribution.

CONCLUSION

The authors report a case of a central retinal vein occlusion with mild retinal findings associated with a remarkable perivenular pattern of paracentral acute middle maculopathy with en face OCT. Follow-up OCT angiography demonstrated significant flow reduction of the deep capillary plexus in a perivenular pattern. The perivenular pattern of paracentral acute middle maculopathy lesions with en face OCT can be an important finding suggestive of a central retinal vein occlusion.