Serotonin-induced constriction of ocular arteries in atherosclerotic monkeys. Implications for ischemic disorders of the retina and optic nerve head

Optical Coherence Tomography Angiography: Revolutionizing Clinical Diagnostics and Treatment in Central Nervous System Disease

Optical coherence tomography angiography (OCTA), as a new generation of non-invasive and efficient fundus imaging technology, can provide non-invasive assessment of vascular lesions in the retina and choroid. In terms of anatomy and development, the retina is referred to as an extension of the central nervous system (CNS). CNS diseases are closely related to changes in fundus structure and blood vessels, and direct visualization of fundus structure and blood vessels provides an effective "window" for CNS research. This has important practical significance for identifying the characteristic changes of various CNS diseases on OCTA in the future, and plays a key role in promoting early screening, diagnosis, and monitoring of disease progression in CNS diseases. This article reviews relevant fundus studies by comparing and summarizing the unique advantages and existing limitations of OCTA in various CNS disease patients, in order to demonstrate the clinical significance of OCTA in the diagnosis and treatment of CNS diseases.

Central serous chorioretinopathy following oral quetiapine

Central serous chorioretinopathy (CSCR) is a chorioretinal disease that is characterized by central vision loss and is usually seen in middle-aged males. It has been associated with the use of various drugs, including corticosteroids and phosphodiesterase inhibitors. We present the case of a 36-year-old male who developed CSCR after a few weeks of irregular use of quetiapine for his sleep problems. The clinical findings of the patient improved shortly after he stopped using the drug, and at the end of the two-month period complete recovery was observed. Quetiapine is an atypical antipsychotic that exerts its effects on dopamine and serotonin receptors. There are studies showing that these neurotransmitters may play a role in the control of choroidal vascular permeability, which is the underlying cause of CSCR. Therefore, we believe that quetiapine may have a causal relationship with CSCR. To our knowledge, this is the first case report documenting full recovery from quetiapine associated CSCR.

Retinal stroke: research models, targets and experimental drugs

INTRODUCTION

Retinal artery occlusion (RAO), often caused by a microembolus and resulting in inner retinal ischemia, could be considered as the retinal analog to cerebral stroke. Although several therapeutic targets have been suggested in animal models of retinal ischemia and several potential treatments have been evaluated on small series of patients, central retinal artery occlusion (CRAO) is still rarely treatable in clinical practice.

AREAS COVERED

Here, we review several animal models of RAO, including increased intraocular pressure, laser, vasoconstriction, embolization and clamp. We also review the pathogenic mechanisms that contribute to cell death cascades during ischemia, and the therapeutic strategies targeting these events. These strategies aim to restore blood flow by fibrinolysis, increase the oxygen or glucose supply, decrease the energy demands, restrict ionic leak fluxes or reduce the detrimental effects of glutamate, calcium and free radicals. The current literature suggests that tPA treatment could be effective for CRAO.

EXPERT OPINION

Eye care professionals must make a rapid and accurate diagnosis and immediately refer patients with acute retinal stroke to specialized centers. CRAO management should also be facilitated by developing local networks to encourage collaboration among ophthalmologists, retina specialists and stroke neurologists.

Establishment of the reproducible branch retinal artery occlusion mouse model and intravital longitudinal imaging of the retinal CX3CR1-GFP+ cells after spontaneous arterial recanalization

Animal models of retinal artery occlusion (RAO) have been widely used in many studies. However, most of these studies prefer using a central retinal artery occlusion (CRAO) which is a typical global ischemia model of the retina, due to the technical limitation of producing single vessel targeted modeling with real-time imaging. A focal ischemia model, such as branch retinal artery occlusion (BRAO), is also needed for explaining interactions, including the immunological reaction between the ischemic retina and adjacent healthy retina. Accordingly, a relevant model for clinical RAO patients has been demanded to understand the pathophysiology of the RAO disease. Herein, we establish a convenient BRAO mouse model to research the focal reaction of the retina. As a photo-thrombotic agent, Rose bengal was intravenously injected into 7 week-old transgenic mice (CX3CR1-GFP) for making embolism occlusion, which causes pathology similarly to clinical cases. In an optimized condition, a 561 nm laser (13.1 mw) was projected to a targeted vessel to induce photo-thrombosis for 27 s by custom-built retinal confocal microscopy. Compared to previous BRAO models, the procedures of thrombosis generation were naturally and minimal invasively generated with real-time retinal imaging. In addition, by utilizing the self-remission characteristics of Rose bengal thrombus, a reflow of the BRAO with immunological reactions of the CX3CR1-GFP⁺ inflammatory cells such as the retinal microglia and monocytes was monitored and analyzed. In this models, reperfusion began on day 3 after modeling. Simultaneously, the activation of CX3CR1-GFP⁺ inflammatory cells, including the increase of activation marker and morphologic change, was confirmed by immunohistochemical (IHC) staining and quantitative real-time PCR. CD86 and Nox2 were prominently expressed on day 3 after the modeling. At day 7, blood flow was almost restored in the large vessels. CX3CR1-GFP⁺ populations in both superficial and deep layers of the retina also increased around even in the BRAO peri-ischemic area. In summary, this study successfully establishes a reproducible BRAO modeling method with convenient capabilities of easily controllable time points and selection of a specific single vessel. It can be a useful tool to analyze the behavior of inflammatory cell after spontaneous arterial recanalization in BRAO and further investigate the pathophysiology of BRAO.

Optical cohorence tomography angiography findings in carotid artery stenosis

AIM

To investigate vascular density (VD) changes in the superficial (SCP) and deep capillary plexus (DCP), radial peripapillar capillary plexus (RPCP), Foveal avascular zone (FAZ) and thickness changes of peripapillary retinal nerve fiber layer (ppRNFL) and choroid (CT) using optical coherence tomography angiography (OCTA) ipsilateral eyes of patient with internal carotid artery stenosis (ICAS) and to compare the obtained values with kontralateral eyes of patients with İCAS and healthy individuals.

METHODS

This prospective cross-sectional case-control study was conducted in 43 patients with a diagnosis of unilateral ICAS and 47 age- and sex-matched healthy subjects. The patients were divided into three groups. Group 1 consisted of ipsilateral eyes of patients with ICAS, group 2 consisted of contralateral eyes of patients with CAS and group 3 comprised healthy individuals without ICAS, All participants underwent a comprehensive ophthalmologic examination including OCTA.

RESULTS

FAZ, Superficial parafoveal and superficial superior VD were significantly lower in group 1 compared to group 2 (p =  < 0.001, p = 0.018 and 0.021, respectively). Group 1 also had lower superficial superior (p = 0.038), superficial inferior (p = 0.034), deep superior (p = 0.034), and deep inferior (p = 0.012) VD compared to group 3. There was no significant difference between the groups in terms of ppRNFLT, whereas CT and RPC mean, superior, and inside-disc VD values were significantly lower in group 1 compared to both group 2 and 3 (p < 0.05).

CONCLUSION

OCTA measurements may be useful in preventing irreversible ocular complications by detecting early structural changes in patients with ICAS before the development of symptomatic ocular ischemic syndrome.

Carotid disease and retinal optical coherence tomography angiography parameters in patients with non-arteritic anterior ischemic optic neuropathy

PURPOSE

In order to analyze the data and retinal microvasculature for non-arteritic anterior ischemic optic neuropathy (NAION), patients were referred to have carotid Doppler ultrasound (CDU) from 2016 to 2020.

METHODS

In this case-control observational study, 30 NAION patients were evaluated with CDU. Twenty-two NAION patients (at least 3 months after the onset of symptoms) and 9 normal subjects underwent a complete ophthalmic examination including optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). NAION eyes and fellow eyes were further divided into two groups based on the presence of carotid stenosis (CS). NAION patients with CS were termed "CS-NAION"; and those without CS were termed "NCS-NAION." Measurements of radial peripapillary capillary vessel density (RPC VD), ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) thicknesses were compared among groups.

RESULTS

Fourteen of 30 NAION patients referred to have carotid Doppler were positive for CS with each one of such referrals having less than 50% stenosis. RNLF, GCC and RPC VDs were reduced in NAION patients' eyes, when compared to controls and the fellow eyes. RPC VD was significantly lower in the temporal-superior (P = 0.037) and the superior-temporal (P = 0.012) sectors of the NCS-NAION patients than in the CS-NAION patients. No significant differences were found between CS-fellow eyes and NCS-fellow eyes in terms of RPC VDs, RNLF or GCC.

CONCLUSION

Results of the study highlight the effect of the carotid artery stenosis on ocular perfusion pressure in the pathogenesis of NAION. More extensive studies are necessary.

Evaluation of hemodynamic changes in nonarteritic anterior ischemic optic neuropathy using multimodality imaging

Background

Nonarteritic anterior ischemic optic neuropathy (NAION) patients experience hypo-perfusion in the short posterior ciliary arteries (SPCAs), however, the cause of hypo-perfusion is unclear. Real-time dynamic hemodynamic observations may provide clues into specific NAION pathogenic mechanisms. We aim to analyze hemodynamic changes occurring in NAION using multimodality imaging. Our specific focus is identifying pathogenic mechanisms underlying SPCA insufficiency in NAION.

Methods

Three-dimensional arterial spin labeling (3D ASL) magnetic resonance imaging (MRI) and three-dimensional time-of-flight (3D-TOF) magnetic resonance angiography (MRA) were performed on 25 NAION patients (50 eyes) and 22 (44 eyes) normal cases were recruited. The diameter of the initial part of the ophthalmic artery and internal carotid artery siphon were measured using MRA. Blood vessel identification and blood flow (BF) were detected using 3D ASL MRI. We measured BF values of the optic nerve head (ONH) region of the retina/choroid complex, optic nerve (ON), temporal lobe, and occipital lobe.

Results

We studied 32 NAION affected eyes, 18 NAION uninvolved eyes, and 44 normal eyes. Diameter of the initial part of ophthalmic artery in the NAION affected eyes was significantly larger than the uninvolved eyes (P=0.026). Diameter of the NAION eyes was 1.33±0.19 mm [mean ± standard deviation (SD)], uninvolved eyes were 1.15±0.21 mm. At a photolabeling delay times (PLD) of 1,500 and 2,500 ms, BF of the ONH and ON in NAION affected eyes was significantly less than uninvolved and normal eyes (pONH <0.001 both at 1,500 and 2,500 ms, pON <0.001 and pON =0.001 at 1,500 and 2,500 ms, respectively). ONH of uninvolved eyes was also significantly less than normal eyes. Additionally, BF of the ONH region correlated with temporal lobe BF, with an R²=0.3231 and 0.2397 at 1,500 and 2,500 ms, respectively. BF of the ONH region also correlated with occipital lobe BF, with an R²=0.2534 and 0.4397 at 1,500 and 2,500 ms, respectively. ON and temporal lobe BF also correlated, with an R²=0.226 and 0.1504 at 1,500 and 2,500 ms, respectively.

Conclusions

Abnormal hemodynamics of small cerebral vessels existed prior to the onset of NAION. A candidate mechanism underlying NAION appears to be transient insufficiency of blood supply and decompensation of ocular vascular regulation.

The Nationwide incidence of retinal artery occlusion following dialysis due to end-stage renal disease in Korea: 2004 through 2013

PURPOSE

To examine the incidence and risk of retinal artery occlusion (RAO) in patients who have undergone dialysis in Korea.

METHODS

A nationwide, population-based study using South Korean national health insurance data from 2004 to 2013 was used for analysis. All patients who began dialysis between 2004 and 2013 and the same number of controls were selected via propensity score matching. The incidence of RAO in the dialysis and control cohorts was calculated for 2004-2013 using washout data from 2003. The multivariable Cox proportional hazards model was used to evaluate the risk of developing RAO in dialysis patients. Cumulative RAO incidence curves were generated using the Kaplan-Meier method. Whether dialysis modalities influenced the incidence of RAO was also evaluated.

RESULTS

76,782 end-stage renal disease (ESRD) patients on dialysis were included in the dialysis cohort and 76,782 individuals were included in the control cohort. During the study period, 293 patients in the dialysis cohort and 99 patients in the control cohort developed RAO. The person-years (PY) incidence of RAO was significantly higher in the dialysis cohort than in the control cohort (dialysis=1.1/1000 PY; control=0.3/1000 PY; p<0.001). The incidence of RAO was not significantly different between the two methods of dialysis (hemodialysis vs. peritoneal dialysis)(p=0.25;log-rank test).

CONCLUSION

The current study provided epidemiological evidence that undergoing dialysis for ESRD was associated with an increased risk of developing RAO. The incidence of RAO rapidly increased as the duration of dialysis increased. These results strengthen the significant role of the renal function in retinal vascular disease.

Investigation of macular and optic nerve head structural changes using spectral domain optical coherence tomography in internal carotid artery stenosis

PURPOSE

To demonstrate differences in optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular thickness in patients with internal carotid artery (ICA) stenosis using spectral domain optical coherence tomography (SD-OCT).

METHODS

A case-controlled study was conducted in 31 patients with a diagnosis of unilateral ICA stenosis (the percentage of stenosis was between 65 and 85%), and 53 age- and sex-matched healthy subjects (control group) from March 2016 to April 2018. The ONH parameters, RNFL, and macular thicknesses in the nine macular quadrants according to the Early Treatment Diabetic Retinopathy Study (ETDRS) were measured using SD-OCT.

RESULTS

The average macular thickness and outer macular quadrants measurements were lower in the ICA stenosis group (P < 0.05). The thickness of the fovea and inner macular quadrants was similar in healthy and patient eyes. Similarly, the ONH and RNFL profiles based on SD-OCT parameters were similar between the groups. There was a negative weak correlation between mean macular and RNFL thicknesses and the duration and percentage of ICA stenosis.

CONCLUSION

The average macular thickness and measurements of outer macular quadrants in the ICA stenosis group were lower than in the control group. Macular changes may occur before symptomatic ocular ischemic syndrome (OIS). SD-OCT macular measurements may be beneficial in the early detection of OIS due to ICA stenosis.

Circulating neurohormone imbalances in canine sudden acquired retinal degeneration syndrome and canine pituitary-dependent hypercortisolism

BACKGROUND

Sudden acquired retinal degeneration syndrome (SARDS) has clinical similarity to pituitary-dependent hypercortisolism (PDH) in dogs. Some studies have identified a greater frequency of SARDS in seasons with reduced daylight hours. Neurohormone imbalances contribute to retinal lesions in other species, warranting further study in dogs with SARDS.

HYPOTHESIS

Dysregulation of circulating melatonin concentration is present in dogs with SARDS but not in dogs with PDH.

ANIMALS

Fifteen client-owned dogs with spontaneous SARDS (median time of vision loss 18 days), 14 normal dogs, and 13 dogs with confirmed PDH.

PROCEDURES

Prospective case-control study. ELISA on samples (obtained in the morning) for measurement of plasma melatonin and dopamine, serum serotonin, urine 6-sulfatoxymelatonin (MT6s), and creatinine. Statistical analysis was performed using 1-way ANOVA, Spearman correlation and receiver operator characteristic area under the curve analysis.

RESULTS

There were no significant differences in circulating melatonin, serotonin or dopamine concentrations between the 3 groups, although the study was underpowered for detection of significant differences in serum serotonin. Urine MT6s:creatinine ratio was significantly higher in dogs with PDH (4.08 ± 2.15 urine [MT6s] ng/mL per mg of urine creatinine) compared with dogs with SARDS (2.37 ± .51, P < .01), but not compared with normal dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

We have identified neurohormone differences between dogs with SARDS and PDH.

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.

Central retinal artery occlusion

The pathogeneses, clinical features, and management of central retinal artery occlusion (CRAO) are discussed. CRAO consists of the following four distinct clinical entities: non-arteritic CRAO (NA-CRAO), transient NA-CRAO, NA-CRAO with cilioretinal artery sparing, and arteritic CRAO. Clinical characteristics, visual outcome, and management very much depend upon the type of CRAO. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual acuity improvement during the first 7 days differs significantly (P < 0.001) among the four types of CRAO; among them, in eyes with initial visual acuity of counting finger or worse, visual acuity improved, remained stable, or deteriorated in NA-CRAO in 22%, 66%, and 12%, respectively; in NA-CRAO with cilioretinal artery sparing in 67%, 33%, and none, respectively; and in transient NA-CRAO in 82%, 18%, and none, respectively. Arteritic CRAO shows no change. Recent studies have shown that administration of local intra-arterial thrombolytic agent not only has no beneficial effect but also can be harmful. Investigations to find the cause and to prevent or reduce the risk of any further visual problems are discussed. Prevalent multiple misconceptions on CRAO are discussed.

Do Patients With Retinal Artery Occlusion Need Urgent Neurologic Evaluation?

PURPOSE

To describe a framework for logical, immediate action to manage patients with retinal artery occlusion.

DESIGN

Literature review and perspective.

METHODS

Review of the literature and the author's experience.

RESULTS

Since embolism is the most common factor causing retinal artery occlusion, to manage these patients, immediate evaluation and management of the source of embolism is critical to prevent further episodes.

CONCLUSIONS

The logical, immediate action to manage patients with retinal artery occlusion is evaluation of the carotid artery and heart for embolism, fasting lipid levels and a complete blood count, rather than neurological evaluation, unless, of course, there are neurological symptoms.

Risk of retinal artery occlusion in patients with diabetes mellitus: A retrospective large-scale cohort study

There is a globally increasing prevalence and incidence of diabetes mellitus (DM). Prolonged hyperglycaemia could lead to both macrovascular damage, such as carotid artery atherosclerosis, and microvascular damage, such as retinal arteriolar narrowing, and might contribute to retinal artery occlusion (RAO). Accordingly, it is important to determine whether DM is a contrubuting factor of RAO. We conducted a retrospective cohort study that included 241,196 DM patients from the Longitudinal Cohort of Diabetes Patients Database who were recruited between 2003 and 2005. An age- and sex-matched non-DM control group included the same number of patients who were selected from the Taiwan Longitudinal Health Insurance Database of 2000. Relevant data of each patient were collected from the index date until December 2013. The incidence and risk of RAO were calculated and compared between the DM and non-DM groups. The hazard ratio for RAO was calculated using Cox proportional hazards regression analysis after adjusting for confounders. The cumulative incidence rate of RAO was calculated by Kaplan-Meier analysis. In total, 317 patients with DM and 144 controls developed RAO during the follow-up period, leading to an incidence rate of RAO in DM patients that was 2.30 times (95% confidence interval [CI] = 1.89-2.80) greater than that in controls. After adjustment for potential confounders, patients with DM were 2.11 times (95% CI, 1.71-2.59) more likely to develop RAO in the total study cohort. In conclusion, DM increases the risk of RAO, which is an interdisciplinary emergency. Close collaboration between endocrinologists and ophthalmologists is important in managing RAO following DM.

Pharmacology of Serotonin Receptors Causing Contraction of Isolated Bovine Posterior Ciliary Arteries: Role in Ocular Blood Flow

PURPOSE

To determine the serotonergic (5HT) receptor subtype mediating the contraction of bovine posterior ciliary arteries (BPCAs) in vitro.

METHODS

Longitudinal isometric tension was measured in BPCA strips (4-5 mm) mounted in 25 mL organ baths containing oxygenated Krebs solution at 37°C. Cumulative contractile concentration-response (C-R) curves were generated for various 5-HT agonists to assess their potencies and maximal degrees of contraction. Multiple agonist C-R curves were also constructed in the presence and absence of receptor-selective antagonists to determine antagonist potencies using Schild plots.

RESULTS

Selective and nonselective agonists for 5-HT receptors elicited concentration-dependent contractile responses in BPCAs with the following rank order of potency: MK-212 > BW723C86 > α-methyl-5-HT >5-methoxy-α-5-methyl-5-HT >> R-DO1 > >5-HT >> cabergoline >> 5-methoxy-dimethyl-tryptamine >> 2-methyl-5-HT >> tryptamine. Interestingly, both 8-OH-DPAT (5HT_1A agonist) and quipazine (5HT₃ agonist) did not elicit contractions in BPCAs. The contractions produced by BW723C86 (5-HT_2B agonist) were antagonized by 5-HT receptor blockers, RS-127445 (5-HT_2B antagonist), and M-100907 (5-HT_2A antagonist), yielding antagonist pA₂ values of 7.5 ± 0.12 (n = 4) and 6.2 ± 0.17 (n = 4), respectively. Furthermore, contractions elicited by MK-212 (5-HT_2C agonist) was blocked by RS-102221 (5-HT_2C antagonist), although noncompetitively.

CONCLUSIONS

On the basis of the pharmacological profile of selective agonists and antagonists, we conclude that serotonin-induced contractions of the BPCA are mediated primarily by a combination of 5HT_2C and/or 5HT_2B receptors. It appears that 5-HT_1A and 5-HT₃ receptors are not involved in the contractile action of BPCAs to serotonin.

OCULAR ARTERIAL OCCLUSIVE DISORDERS AND CAROTID ARTERY DISEASE

OBJECTIVE

To compare prevalence of carotid artery disease and its various types of lesions in different types of ocular arterial occlusive disorders.

DESIGN

Cohort study.

SUBJECTS

614 consecutive patients (728 eyes) with ocular arterial occlusive disorders.

METHODS

At first visit, all patients had a detailed ophthalmic and medical history, comprehensive ophthalmic evaluation, and carotid artery evaluation (by Doppler/angiography) on the side of ocular arterial occlusion, and echocardiography. The same ophthalmic evaluation was performed at each follow-up visit. Ocular arterial occlusive disorders were divided into central (CRAO) and branch (BRAO) retinal artery occlusion, ocular ischemic syndrome (OIS), non-arteritic anterior ischemic optic neuropathy (NA-AION) and amaurosis fugax (AF).

MAIN OUTCOME MEASURES

Carotid artery and echocardiographic abnormalities, and incidence of transient ischemic attack (TIA)/stroke and myocardial ischemia.

RESULTS

The study consists of a cohort of 266 eyes with NA-AION, 203 with CRAO, 127 with BRAO, 80 with OIS and 52 with AF. Carotid artery stenosis on the involved side was worse in AF and OIS compared to BRAO, CRAO, and NA-AION (p<0.0001). Presence of carotid artery plaques on the involved side was significantly higher in OIS, AF, and CRAO compared to NA-AION (p=0.002, p=0.003, and p=0.0003, respectively). Echocardiography revealed an embolic source in 61% of CRAO and 53% of BRAO compared to only 3% of NA-AION patients (p<0.0001). TIA/stroke before or after onset of ocular condition occurred in 17% of OIS, 11% of AF, 7% of CRAO, 6% of NA-AION, and 3% of BRAO patients. Kaplan-Meier estimate of the incidence of TIA /stroke within 3 months after onset was 6% (95% CI: 2%, 17%) for OIS, 3% (95% CI: 0.4%, 19%) for AF, and 1% (95% CI: 0.3%, 4.1%) for CRAO. Report of myocardial ischemia before or after onset of ocular condition was 52% in AF, 22% in OIS, 22% in BRAO, 21% in CRAO, and 6% in NA-AION patients.

CONCLUSIONS

The incidence of carotid artery stenosis and plaques, cardiac embolic source, TIA/stroke and myocardial ischemia differ among various ocular arterial occlusive disorders. The role of embolism and hemodynamic disturbances caused by carotid artery disease in these disorders is discussed.

Central retinal artery occlusion following orbital tumor resection: Is rapid intervention effective?

A 52-year-old male patient presented at our hospital with unilateral proptosis and vision loss in his left eye. Imaging evaluations showed orbital tumor, so the patient underwent surgery. About an hour later after tumor removal, patient developed sudden vision loss and became no light perception. Fundus evaluation revealed central retinal artery occlusion (CRAO). The patient was treated immediately with ocular massage and anterior chamber paracentesis as well as systemic therapy with mannitol and intravenous administration of acetazolamide. After thirty minutes, he recovered perception to light and then hand motion and 2 h later, it was improved to 1 m counting finger. CRAO following orbital tumor has not been reported before. We recommend ocular examination in all patients that undergo orbital surgery immediately to 2–3 h after surgery.

Serotonin receptor 2C regulates neurite growth and is necessary for normal retinal processing of visual information

Serotonin (5HT) is present in a subpopulation of amacrine cells, which form synapses with retinal ganglion cells (RGCs), but little is known about the physiological role of retinal serotonergic circuitry. We found that the 5HT receptor 2C (5HTR2C) is upregulated in RGCs after birth. Amacrine cells generate 5HT and about half of RGCs respond to 5HTR2C agonism with calcium elevation. We found that there are on average 83 5HT+ amacrine cells randomly distributed across the adult mouse retina, all negative for choline acetyltransferase and 90% positive for tyrosine hydroxylase. We also investigated whether 5HTR2C and 5HTR5A affect RGC neurite growth. We found that both suppress neurite growth, and that RGCs from the 5HTR2C knockout (KO) mice grow longer neurites. Furthermore, 5HTR2C is subject to post-transcriptional editing, and we found that only the edited isoform's suppressive effect on neurite growth could be reversed by a 5HTR2C inverse agonist. Next, we investigated the physiological role of 5HTR2C in the retina, and found that 5HTR2C KO mice showed increased amplitude on pattern electroretinogram. Finally, RGC transcriptional profiling and pathways analysis suggested partial developmental compensation for 5HTR2C absence. Taken together, our findings demonstrate that 5HTR2C regulates neurite growth and RGC activity and is necessary for normal amplitude of RGC response to physiologic stimuli, and raise the hypothesis that these functions are modulated by a subset of 5HT+/ChAT-/TH+ amacrine cells as part of retinal serotonergic circuitry. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 419-437, 2017.

Risk of Retinal Artery Occlusion in Patients With End-Stage Renal Disease: A Retrospective Large-Scale Cohort Study

There is globally increasing prevalence and incidence in end-stage renal disease (ESRD). These patients are frequently reported to have retinal abnormalities and both diseases share some systemic risk factors. Hence, it is clinically relevant to determine whether ESRD is a predictor of retinal artery occlusion (RAO).To investigate the risk of RAO in ESRD patients.A retrospective, nationwide, matched cohort study. The study included 93,766 ESRD patients recruited between 2000 and 2009 from the Taiwan National Health Insurance Research Database. The same number control group included age- and sex-matched patients without ESRD selected from the Taiwan Longitudinal Health Insurance Database, 2000. Data for each patient were collected from the index date until December 2011.The incidence and risk of RAO were compared between the 2 groups. The hazard ratio (HR) for RAO after adjustment for potential confounders was calculated using Cox proportional hazards regression. Kaplan-Meier analysis was used to calculate the cumulative RAO incidence rate.In total, 237 ESRD patients and 73 controls exhibited RAO during follow-up; thus, the RAO incidence rate in ESRD patients was 4.49 times (95% confidence interval (CI), 3.45-5.83) that in the control patients. After adjustment for potential confounders, including diabetes mellitus, hypertension, hyperlipidemia, congestive heart failure, and coronary artery disease, ESRD patients were 2.78 times (95% CI, 2.02-3.84) more likely to develop RAO in cohort for the total sample. Among patients with hypertension, the RAO incidence rate was significantly higher in the ESRD group, and hypertension significantly increased RAO risk even after adjustment for other confounders in the cohort.ESRD increases the risk of RAO, particularly in ESRD patients with hypertension. Therefore, clinicians should educate ESRD patients about RAO and ensure appropriate blood pressure control.

The risk of acute coronary syndrome after retinal artery occlusion: a population-based cohort study

AIM

To investigate the risk of acute coronary syndrome (ACS) following retinal artery occlusion (RAO).

METHODS

The study cohort included all patients diagnosed with RAO between January 1999 and December 2008 (n=688) in the Taiwan Longitudinal Health Insurance Database 2000. The control group included randomly selected patients (n=4128) from the same database that were matched to the study group, using a propensity score, for age, gender, and comorbid diabetes mellitus, hypertension, hyperlipidaemia, chronic renal disease and atrial fibrillation status. The ACS-free survival rate was calculated using Kaplan-Meier analysis. Cox proportional hazard regression analysis was used to obtain the adjusted HR for ACS after adjustment for potential confounding factors. The incidence and risk of ACS were compared between the RAO and control groups.

RESULTS

Thirty-seven patients in the RAO group (5.38%) and 138 controls (3.34%) had ACS (p=0.0063) during the follow-up period, resulting in a significantly higher risk of ACS in the RAO group (HR=1.67, 95% CI 1.16 to 2.40). After adjustment for potential confounders, the HR for developing ACS in the RAO group was 1.72 (95% CI 1.20 to 2.47) times higher than that of controls. When stratified by RAO type, the adjusted HR for ACS was 3.57 (95% CI 2.09 to 6.10) for the central RAO subgroup.

CONCLUSIONS

We found that RAO increased the risk for ACS. We recommend thorough follow-up cardiovascular examinations and medical prevention for ACS in patients following RAO.

Integrative analysis of ocular complications in atherosclerosis unveils pathway convergence and crosstalk

Atherosclerosis is a life-threatening disease and a major cause of mortalities worldwide. While many of the atherosclerotic sequelae are reflected as microvascular effects in the eye, the molecular mechanisms of their development is not yet known. In this study, we employed a systems biology approach to unveil the most significant events and key molecular mediators of ophthalmic sequelae caused by atherosclerosis. Literature mining was used to identify the proteins involved in both atherosclerosis and ophthalmic diseases. A protein-protein interaction (PPI) network was prepared using the literature-mined seed nodes. Network topological analysis was carried out using Cytoscape, while network nodes were annotated using database for annotation, visualization and integrated discovery in order to identify the most enriched pathways and processes. Network analysis revealed that mitogen-activated protein kinase 1 (MAPK1) and protein kinase C occur with highest betweenness centrality, degree and closeness centrality, thus reflecting their functional importance to the network. Our analysis shows that atherosclerosis-associated ophthalmic complications are caused by the convergence of neurotrophin signaling pathways, multiple immune response pathways and focal adhesion pathway on the MAPK signaling pathway. The PPI network shares features with vasoregression, a process underlying multiple vascular eye diseases. Our study presents a first clear and composite picture of the components and crosstalk of the main pathways of atherosclerosis-induced ocular diseases. The hub bottleneck nodes highlight the presence of molecules important for mediating the ophthalmic complications of atherosclerosis and contain five established drug targets for future therapeutic modulation efforts.

Regulation of lung oxidative damage by endogenous superoxide dismutase in sepsis

Background

The purpose of this research is to study the relationship between superoxide dismutase (SOD) and lung redox state in an animal model of sepsis.

Methods

Sepsis was induced in rats by the cecal ligation and perforation model (CLP). After 3, 6, and 12 h, CLP protein content and expression of SOD1, SOD2, and SOD3 were evaluated, and SOD activity was assessed. Oxidative damage was determined by quantifying nitrotyrosine content. Lung localization of SOD3 was performed by immunohistochemistry. The protective effect of a SOD mimetic on oxidative damage, inflammation, and lung permeability was assessed 12 and 24 h after sepsis induction.

Results

Lung levels of SOD1 decreased 3 and 12 h after sepsis, but SOD2 and SOD3 increased, as well as SOD activity. These alterations were not associated with changes in sod gene expression. Nitrotyrosine levels increased 3 and 12 h after sepsis. The administration of a SOD mimetic decreased nitrotyrosine and proinflammatory cytokine levels and improved lung permeability.

Conclusions

SOD2 and SOD3 increased after sepsis induction, but this was insufficient to protect the lung. Treatments based on SOD mimetics could have a role in lung injury associated with sepsis.

A review of central retinal artery occlusion: clinical presentation and management

Central retinal artery occlusion (CRAO) is an ophthalmic emergency and the ocular analogue of cerebral stroke. Best evidence reflects that over three-quarters of patients suffer profound acute visual loss with a visual acuity of 20/400 or worse. This results in a reduced functional capacity and quality of life. There is also an increased risk of subsequent cerebral stroke and ischaemic heart disease. There are no current guideline-endorsed therapies, although the use of tissue plasminogen activator (tPA) has been investigated in two randomized controlled trials. This review will describe the pathophysiology, epidemiology, and clinical features of CRAO, and discuss current and future treatments, including the use of tPA in further clinical trials.

Treatment options for central retinal artery occlusion

OPINION STATEMENT

Central retinal artery occlusion (CRAO) is an ocular emergency and is the ocular analogue of cerebral stroke. It results in profound, usually monocular vision loss, and is associated with significant functional morbidity. The risk factors for CRAO are the same atherosclerotic risk factors as for stroke and heart disease. As such, individuals with CRAO may be at risk of ischemic end organ damage such as a cerebral stroke. Therefore, the management of CRAO is not only to restore vision, but at the same time to manage risk factors that may lead to other vascular conditions. There are a number of therapies that has been used in the treatment of CRAO in the past. These include carbogen inhalation, acetazolamide infusion, ocular massage and paracentesis, as well as various vasodilators such as intravenous glyceryl trinitrate. None of these "standard agents" have been shown to alter the natural history of disease definitively. There has been recent interest shown in the use of thrombolytic therapy, delivered either intravenously or intra-arterially by direct catheterisation of the ophthalmic artery. Whilst a number of observational series have shown that the recovery of vision can be quite dramatic, two recent randomised controlled trials have not demonstrated efficacy. On the contrary, intra-arterial delivery of thrombolytic may result in an increased risk of intracranial and systemic haemorrhage, while the intravenous use of tissue plasminogen activator (tPA) was not shown to be efficacious within 24 h of symptom onset. Nevertheless, both of these studies have shown one thing in common, and that is for treatment to be effective in CRAO, it must be deployed within a short time window, probably within 6 h of symptom onset. Therefore, while CRAO is a disease that does not have a treatment, nevertheless it needs to follow the same principles of treatment as any other vascular end organ ischaemic disease. That is, to attempt to reperfuse ischemic tissue as quickly as possible and to institute secondary prevention early.

Characteristics of patients with a localized retinal nerve fiber layer defect and normal optic disc appearance

PURPOSE

To investigate the characteristics of patients with a localized retinal nerve fiber layer (RNFL) defect and normal optic disc appearance compared with normal tension glaucoma (NTG) patients.

METHODS

A total of 40 patients with an unchanged RNFL defect for more than 5 years and normal optic disc appearance, who were presumed as non-glaucomatous patients, were enrolled (group A). We recruited 40 age-matched patients with NTG (group B). On the RNFL photographs, we evaluated angles of RNFL defects. Angle α and β were the angles made by the line 'L' from the center of the fovea to the disc center and the lines 'A' and 'B' from the disc center to the disc margin where the proximal and the distal border of the defect met, respectively. Angle θ was the angular width of the defect. Angle γ was the angle made by lines 'L' and 'R', which divides angle θ into a 2 :1 ratio from line 'A' to line 'B'. We compared systemic diseases, baseline IOP, and location and angles of the RNFL defects between the two groups.

RESULTS

Systemic diseases and superotemporal RNFL defects in group A were significantly greater than those in group B (P<0.001). Angle α was greater in group A, but angle β, θ, and γ were smaller in group A (P<0.05).

CONCLUSION

If the patients with a superotemporal RNFL defect and normal optic disc appearance had systemic diseases and distal borders of the defects are closer to the macula, glaucoma is less likely.

Uncommon ophthalmologic disorders in intensive care unit patients

Ophthalmologic complications are frequently encountered in intensive care unit (ICU) patients (Grixti et al. Ocul Surf 2012;10(1):26-42). However, eye care is often overlooked in the critical care setting or just limited to the ocular surface because treatment is focussed on the management of organ failures. Lack of awareness about other less common intraocular sight-threatening conditions may have a devastating effect on the patient's vision. To identify specific, frequently missed uncommon ocular disorders in ICU, a literature review using the keywords "Intensive Care," "Eye care," "ITU," "ICU," "Ophthalmological disorders," "Eye disorders" was performed. The databases of CINAHL, PuBMed, EMBASE, and Cochrane library were searched. The higher quality studies are summarized in the table with statements of methodology to clarify the level of evidence. The most prevalent ophthalmologic disorders identified in critically ill subjects include exposure keratopathy, chemosis, and microbial keratitis. In addition, uncommon eye disorders reported in ICU include metastatic endogenous endophthalmitis, acute primary angle closure, ischemic optic neuropathy, pupil abnormalities, vascular occlusions, and rhino-orbital cerebral mucormycosis. Early diagnosis and effective treatment will help to prevent visual loss.

Acute retinal arterial occlusive disorders

The initial section deals with basic sciences; among the various topics briefly discussed are the anatomical features of ophthalmic, central retinal and cilioretinal arteries which may play a role in acute retinal arterial ischemic disorders. Crucial information required in the management of central retinal artery occlusion (CRAO) is the length of time the retina can survive following that. An experimental study shows that CRAO for 97min produces no detectable permanent retinal damage but there is a progressive ischemic damage thereafter, and by 4h the retina has suffered irreversible damage. In the clinical section, I discuss at length various controversies on acute retinal arterial ischemic disorders. Classification of acute retinal arterial ischemic disorders: These are of 4 types: CRAO, branch retinal artery occlusion (BRAO), cotton wool spots and amaurosis fugax. Both CRAO and BRAO further comprise multiple clinical entities. Contrary to the universal belief, pathogenetically, clinically and for management, CRAO is not one clinical entity but 4 distinct clinical entities - non-arteritic CRAO, non-arteritic CRAO with cilioretinal artery sparing, arteritic CRAO associated with giant cell arteritis (GCA) and transient non-arteritic CRAO. Similarly, BRAO comprises permanent BRAO, transient BRAO and cilioretinal artery occlusion (CLRAO), and the latter further consists of 3 distinct clinical entities - non-arteritic CLRAO alone, non-arteritic CLRAO associated with central retinal vein occlusion and arteritic CLRAO associated with GCA. Understanding these classifications is essential to comprehend fully various aspects of these disorders. Central retinal artery occlusion: The pathogeneses, clinical features and management of the various types of CRAO are discussed in detail. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual acuity improvement during the first 7 days differs significantly (p<0.001) among the 4 types of CRAO; among them, in eyes with initial visual acuity of counting finger or worse, visual acuity improved, remained stable or deteriorated in non-arteritic CRAO in 22%, 66% and 12% respectively; in non-arteritic CRAO with cilioretinal artery sparing in 67%, 33% and none respectively; and in transient non-arteritic CRAO in 82%, 18% and none respectively. Arteritic CRAO shows no change. Recent studies have shown that administration of local intra-arterial thrombolytic agent not only has no beneficial effect but also can be harmful. Prevalent multiple misconceptions on CRAO are discussed. Branch retinal artery occlusion: Pathogeneses, clinical features and management of various types of BRAO are discussed at length. The natural history of visual acuity outcome shows a final visual acuity of 20/40 or better in 89% of permanent BRAO cases, 100% of transient BRAO and 100% of non-arteritic CLRAO alone. Cotton wools spots: These are common, non-specific acute focal retinal ischemic lesions, seen in many retinopathies. Their pathogenesis and clinical features are discussed in detail. Amaurosis fugax: Its pathogenesis, clinical features and management are described.

The optic nerve head in acquired optic neuropathies

Acquired optic neuropathies are a common cause of blindness in adults, and are associated with characteristic morphological changes at the optic nerve head. Accurate and prompt clinical diagnosis, supplemented with imaging where appropriate, is essential to optimize management of the optic neuropathy and to counsel the patient appropriately on its natural history. History taking, optic disc findings, visual field assessment and imaging of the nerve head and surrounding retinal nerve fiber layer are all paramount to achieving the correct diagnosis. This Review highlights the optic nerve head features that are common to the acquired optic neuropathies, and describes the features that can be used to differentiate these various conditions.

Retinal artery occlusion: associated systemic and ophthalmic abnormalities

OBJECTIVE

To investigate systematically the various associated systemic and ophthalmic abnormalities in different types of retinal artery occlusion (RAO).

DESIGN

Cohort study.

PARTICIPANTS

We included 439 consecutive untreated patients (499 eyes) with RAO first seen in our clinic from 1973 to 2000.

METHODS

At first visit, all patients underwent detailed ophthalmic and medical history, and comprehensive ophthalmic evaluation. Visual evaluation was done by recording visual acuity, using the Snellen visual acuity chart, and visual fields with a Goldmann perimeter. Initially they also had carotid Doppler/angiography and echocardiography. The same ophthalmic evaluation was performed at each follow-up visit.

MAIN OUTCOME MEASURES

Demographic features, associated systemic and ophthalmic abnormalities, and sources of emboli in various types of RAO.

RESULTS

We classified RAO into central (CRAO) and branch (BRAO) artery occlusion. In both nonarteritic (NA) CRAO and BRAO, the prevalence of diabetes mellitus, arterial hypertension, ischemic heart disease, and cerebrovascular accidents were significantly higher compared with the prevalence of these conditions in the matched US population (all P<0.0001). Smoking prevalence, compared with the US population, was significantly higher for males (P = 0.001) with NA-CRAO and for women with BRAO (P = 0.02). Ipsilateral internal carotid artery had > or =50% stenosis in 31% of NA-CRAO patients and 30% of BRAO, and plaques in 71% of NA-CRAO and 66% of BRAO. An abnormal echocardiogram with an embolic source was seen in 52% of NA-CRAO and 42% of BRAO. Neovascular glaucoma developed in only 2.5% of NA-CRAO eyes.

CONCLUSIONS

This study showed that, in CRAO as well as BRAO, the prevalence of various cardiovascular diseases and smoking was significantly higher compared with the prevalence of these conditions in the matched US population. Embolism is the most common cause of CRAO and BRAO; plaque in the carotid artery is usually the source of embolism and less commonly the aortic and/or mitral valve. The presence of plaques in the carotid artery is generally of much greater importance than the degree of stenosis in the artery. Contrary to the prevalent misconception, we found no cause-and-effect relationship between CRAO and neovascular glaucoma.

Diabetic papillopathy and its relation to optic nerve ischemia

PURPOSE

This presentation exhibits a case report and review of multiple reported cases of hyperemic optic disc swelling in patients with diabetes. After excluding all other known causes of optic nerve insult, this pathology has typically been labeled as diabetic papillopathy.

CASE REPORT

We offer a case of a 65-year-old veteran with unilateral hyperemic optic disc swelling, presenting with minimal optic nerve dysfunction. After an extensive evaluation to rule out other causative pathology, this patient was diagnosed with diabetic papillopathy.

CONCLUSIONS

Presented are clinical data of a case of diabetic papillopathy and a literature review to delineate the typical published clinical characteristics and course of this disease process. We also review literature to summarize the typical characteristics of anterior ischemic optic neuropathy and offer a hypothesis to reconcile the dilemmas regarding its relation to diabetic papillopathy.

Endothelial function in the time of the giants

Paul Vanhoutte is one of the fathers of vascular biology. Among his great contributions, he demonstrated that endothelium modulates vasomotor response to vasoactive products (including serotonin) that are released when platelets aggregate in an artery. He found in arteries ex vivo that when endothelium is dysfunctional, in atherosclerosis or hypertension, normal relaxation to aggregation of platelets is impaired and vessels may contract. He proposed that this mechanism may predispose to vasospasm. The results of our experiments in vivo indicate that atherosclerosis greatly potentiates vasoconstrictor responses to serotonin in the limb, brain, and eye of monkeys. We proposed that transient ischemic attacks may be mediated by platelet-induced vasospasm. We observed endothelial dysfunction in atherosclerotic monkeys, with improvement of endothelial function when hypercholesterolemia was corrected. Recently, we studied the aortic valve, which has unique endothelium, in hypercholesterolemic mice to examine the pathophysiology of aortic valvular stenosis. Oxidative stress is increased in stenotic valves, and severe aortic stenosis develops in about one third of old, hypercholesterolemic mice. In stenotic aortic valves from humans, there is increased oxidative stress near calcified regions of the valves. Oxidative stress may trigger expression of pro-calcific genes in the aortic valve. Finally, we have used gene transfer of extracellular superoxide dismutase (ecSOD) to study endothelial effects of oxidative stress. Gene transfer of normal ecSOD improves endothelial dysfunction in several disease states, but gene transfer of ecSOD(R213G), a gene variant of ecSOD that is common in humans, fails to improve endothelial function. Gene transfer approaches may be useful to study mechanisms by which gene variants predispose to endothelial dysfunction and vascular disease.

Selective serotonin reuptake inhibitors: a review of its effects on intraocular pressure

The increase in serotonin (5-HT) neurotransmission is considered to be one of the most efficacious medical approach to depression and its related disorders. The selective serotonin reuptake inhibitors (SSRIs) represent the most widely antidepressive drugs utilized in the medical treatment of depressed patients. Currently available SSRIs include fluoxetine, sertraline, paroxetine, fluvoxamine, citalopram and escitalopram. The primary SSRIs pharmacological action's mechanism consists in the presynaptic inhibition on the serotonin reuptake, with an increased availability of this amine into the synaptic cleft. Serotonin produces its effects as a consequence of interactions with appropriate receptors. Seven distinct families of 5-HT receptors have been identified (5-HT(1) to 5-HT(7)), and subpopulations have been described for several of these. The interaction between serotonin and post-synaptic receptors mediates a wide range of functions. The SSRIs have a very favorable safety profile, although clinical signs of several unexpected pathologic events are often misdiagnosed, in particular, those regarding the eye. In all cases reported in the literature the angle-closure glaucoma represents the most important SSRIs-related ocular adverse event. Thus, it is not quite hazardous to hypothesize that also the other reported and unspecified visual disturbances could be attributed - at least in some cases - to IOP modifications. The knowledge of SSRIs individual tolerability, angle-closure predisposition and critical IOP could be important goals able to avoid further and more dangerous ocular side effects.

Central retinal artery occlusion: visual outcome

PURPOSE

To investigate systematically the natural history of visual outcome in central retinal artery occlusion (CRAO).

DESIGN

Cohort study.

METHODS

At entry, 244 consecutive patients (260 eyes) with CRAO (seen consecutively from 1973 to 2000) had a detailed ocular and medical history and ocular evaluation. CRAO eyes were classified into four categories: non-arteritic (NA) CRAO (171 eyes), NA-CRAO with cilioretinal artery sparing (35), transient NA-CRAO (41), and arteritic CRAO (13).

RESULTS

Within 7 days of onset of CRAO, initial visual acuity differed among the four CRAO types (P < .0001). In eyes with vision of counting fingers or worse, it improved in 82% of eyes with transient NA-CRAO, 67% of eyes with NA-CRAO with cilioretinal artery sparing, and 22% of eyes with NA-CRAO. Visual acuity improved primarily within the first 7 days (P < .0001). In the central 30-degree visual field, central scotoma was most common. Central visual field improved in 39% with transient NA-CRAO, 25% with NA-CRAO with cilioretinal artery sparing, and 21% with NA-CRAO. Peripheral visual field was normal in 62.9% of eyes with transient NA-CRAO and 22.1% in those with NA-CRAO. In 51.9% of eyes with NA-CRAO, the only remaining visual field was a peripheral island. Peripheral fields improved in NA-CRAO (39%) and in transient NA-CRAO (39%).

CONCLUSIONS

Classification of CRAO is crucial for understanding differences in visual outcome. Marked improvement in visual acuity and visual field can occur without treatment and is determined by several factors. Visual field information is essential to evaluate visual disability in CRAO.

Retinal serotonin, eye growth and myopia development in chick

Myopia (short-sightedness) is a visual problem associated with excessive eye growth and vitreous chamber expansion. Within the eye serotonin (5-hydroxytryptamine, 5-HT) appears to have a variety of effects, it alters retinal amacrine cell processing, increases intraocular pressure, constricts ocular blood vessels, and is also mitogenic. This study sought to determine the role of the retinal serotonin system in eye growth regulation. Myopia was produced in 7-day-old chicks using -15 D spectacle lenses (LIM) and form deprivation (FDM). The effect on LIM and FDM of daily intravitreal injections of a combination of 5-HT receptor antagonists (1, 10, 50 microM), 5-HT(2) selective antagonist (Mianserin 0.5, 20 microM) or 5-HT (1, 10, 50 microM) were assessed. Counts were performed of serotonin and tyrosine hydroxylase positive neurons and the relative density used to account for areal changes due to eye growth. The effect of LIM and lens-induced hyperopia (LIH) on the numbers of 5-HT-containing amacrine cells in the retina were then determined. The combination of 5-HT receptor antagonists inhibited LIM by approximately half (1 microM RE: -7.12+/-1.0 D, AL: 0.38+/-0.06 mm vs. saline RE: -13.19+/-0.65 D, AL: 0.64+/-0.03 mm. RE: p<0.01, AL: p<0.01), whereas FDM was not affected (1 microM RE: -8.88+/-1.10 D vs. saline RE: -9.28+/-1.38 D). The selective antagonist was slightly less effective at inhibiting LIM (0.5 microM RE: -9.02+/-1.01 D). These data suggest that serotonin has a stimulatory role in LIM, although high doses of serotonin were inhibitory (1 microM RE: -9.30+/-1.34 D). 5-HT immunoreactivity was localised to a subset of amacrine cell bodies in the inner nuclear layer of the retina, and to two synaptic strata in the inner plexiform layer. LIM eyes had increased numbers of 5-HT-containing amacrine cells in the central retina (12.5%). Collectively, these results suggest that manipulations to the serotonin system can alter the eye growth process but the role of this transmitter system within this process remains unclear.

Prevalent misconceptions about acute retinal vascular occlusive disorders

Acute retinal vascular occlusive disorders collectively constitute one of the major causes of blindness or seriously impaired vision, and yet there is marked controversy on their pathogeneses, clinical features and particularly their management. This is because the subject is plagued by multiple misconceptions. These include that: (i) various acute retinal vascular occlusions represent a single disease; (ii) estimation of visual acuity alone provides all the information necessary to evaluate visual function; (iii) retinal venous occlusions are a single clinical entity; (iv) retinal vein occlusion is essentially a disease of the elderly and is not seen in the young; (v) central retinal vein occlusion (CRVO) is one disease; (vi) fluorescein fundus angiography is the best test to differentiate ischemic from nonischemic CRVO; (vii) the site of occlusion in CRVO is invariably at the lamina cribrosa; (viii) clinical picture of CRVO is often due to compression or strangulation of the central retinal vein (CRV) in the lamina cribrosa and not its occlusion; (ix) an eye can develop both CRVO and central retinal artery occlusion (CRAO) simultaneously; (x) every eye with CRVO is at risk of developing neovascular glaucoma; (xi) lowering intraocular pressure (IOP) helps to improve retinal circulation in an eye with CRVO; (xii) every patient with retinal vein occlusion should have complete hematologic and coagulation evaluation; (xiii) the natural history of CRVO does not usually involve spontaneous visual improvement; (xiv) management of CRVO is similar to that of venous thrombosis anywhere else in the body, i.e. with aspirin and/or anti-coagulants; (xv) fibrinolytic agents can dissolve an organized thrombus in the CRV; (xvi) it is beneficial to lower blood pressure in patients with CRVO; (xvii) panretinal photocoagulation used in ischemic retinal venous occlusive disorders has no deleterious side-effects; (xviii) glaucoma or ocular hypertension can cause branch retinal vein occlusion; (xix) branch retinal vein occlusion can cause neovascular glaucoma; (xx) in eyes with CRAO, the artery is usually not completely occluded; (xxi) CRAO is always either embolic or thrombotic in origin; (xxii) amaurosis fugax is always due to retinal ischemia secondary to transient retinal arterial embolism; (xxiii) asymptomatic plaque(s) in retinal arteries do not require a detailed evaluation; (xxiv) retinal function can improve even when acute retinal ischemia due to CRAO has lasted for 20h or more; (xxv) CRAO, like ischemic CRVO, can result in development of ocular neovascularization; (xxvi) panretinal photocoagulation is needed for "disc neovascularization" in CRAO; (xxvii) fibrinolytic agents are the treatment of choice in CRAO; (xxviii) there is no chance of an eye with retinal arterial occlusion having spontaneous visual improvement; (xxix) absence of any abnormality on Doppler evaluation of the carotid artery or echography of the heart always rules out those sites as the source of embolism; and (xxx) absence of an embolus in the retinal artery means the occlusion was not caused by an embolus. The major cause of all these misconceptions is the lack of a proper understanding of basic scientific facts related to the various diseases. The objective of this paper is to discuss these misconceptions, based on these scientific facts, to clarify the understanding of these blinding disorders, and to place their management on a rational, scientific basis.

Blindness in the Intensive Care Unit: Possible Role for Vasopressors?

Blindness caused by ischemic optic neuropathy in the hospital setting occurs perioperatively and in critically ill patients, but its etiology remains ill defined. We describe four critically ill patients who developed blindness within 1 mo of one another. Three cases occurred outside of the operative arena. Potential risk factors for the development of ischemic optic neuropathy, such as use of vasopressors, venous congestion, and hypotension, are described.

Central retinal artery occlusion. Retinal survival time

PURPOSE

To investigate the retinal survival time following central retinal artery occlusion (CRAO).

METHODS

In 38 elderly, atherosclerotic and hypertensive rhesus monkeys, transient CRAO (varying from 97 to 240 min) was produced by temporarily clamping the CRA at its site of entry into the optic nerve. Stereoscopic color fundus photography, fluorescein fundus angiography, electroretinography (ERG), and visual evoked potential (VEP) recording were performed before and during CRA clamping, after unclamping, and serially thereafter. After unclamping of the CRA, the animals were followed for variable lengths of time (median duration 8.14 weeks). Finally, the eyes and optic nerves were examined histologically. The data on ERG changes were analyzed in the following four time frames: (1) baseline before CRA clamping, (2) during CRA clamping, (3) immediately after unclamping, and (4) at the end of follow-up. Duration of CRAO was divided into four groups: 97, 105-120, 150-165, and > or = 180 min.

RESULTS

A 'negative ERG' appeared during CRA clamping. With removal of the CRA clamp, there was b-wave recovery, with differential rates of recovery of ERG-eyes with shorter CRAO recovered sooner than those with longer occlusion. On removal of clamp, recovery was seen in scotopic 24 dB b-wave, photopic 0 dB single flash b-wave and 30 Hz flicker, with the b/a ratio of the combined rod and cone response and selective rod response showing statistically significant differences amongst the shorter and longer periods of CRAO. A delayed normalization of the depressed b/a ratio immediately after CRA reperfusion may indicate high-grade ischemic damage. At the final follow-up test session, no clear-cut derangement of any ERG parameter was seen for any group, with subtotal b-wave amplitude recovery for all groups. Longer CRAO produced incomplete VEP recovery. On histology, in the macular retina, eyes with CRAO for 97 min showed practically no damage, but duration of CRAO was found to be significantly associated with the amount of damage in the ganglion cell layer (p = 0.009) and inner nuclear layer (p = 0.017). Outer nuclear and plexiform layers and photoreceptors showed no damage at all with CRAO. There was no significant association of the ERG measures and histologic changes with any of the residual retinal circulation variables.

CONCLUSIONS

Our electrophysiologic, histopathologic and morphometric studies showed that the retina of old, atherosclerotic, hypertensive rhesus monkeys suffers no detectable damage with CRAO of 97 min but above that level, the longer the CRAO, the more extensive the irreversible damage. The study suggests that CRAO lasting for about 240 min results in massive irreversible retinal damage.

The morphology of an infarct in nonarteritic anterior ischemic optic neuropathy

OBJECTIVE

The mechanism by which nonarteritic anterior ischemic optic neuropathy (NAION) causes an infarct in the optic nerve is controversial. We studied the three-dimensional anatomic configuration of a NAION infarct to better elucidate its pathophysiology.

DESIGN

Case report with clinicopathologic correlation.

METHODS

Serial sections of the optic nerve from a previously reported patient diagnosed with NAION 20 days before death were studied. Every fourth slide was stained with hematoxylin-eosin, photographed, and digitized. NIH Image 1.62 was used to reconstruct the nerve in all three dimensions, and the infarct morphology was analyzed.

MAIN OUTCOME MEASURES

Morphology of the reconstructed optic nerve infarct.

RESULTS

The area of axonal loss within each section of the optic nerve was identified and reconstructed. The loss was in the superior part of the nerve, encircling the central retinal artery at its greatest extent. Remaining areas of the nerve appeared healthy, and, notably, the periphery of the uninvolved inferior portion of the nerve was normal. Three-dimensional analysis revealed two distinct areas of infarct at the posterior extent of the lesion which coalesced toward the center of the lesion and finally tapered as the infarct reached the optic nerve head. Sagittal reconstructions gave the appearance of a two-pronged fork posteriorly connecting to a single "handle" anteriorly. There was no obvious correlation between the configuration of the infarct and any single vascular territory. The total length of the nerve involved by the infarct was approximately 1.5 mm.

CONCLUSIONS

The morphology of this NAION infarct is not consistent with disease of large or small vessels and, more likely, represents a form of compartment syndrome that causes tissue ischemia.

Pathogenesis of nonarteritic anterior ischemic optic neuropathy

Based on histopathology, electron microscopic corrosion cast studies, optic nerve blood flow studies, and clinical data, the pathogenesis of idiopathic nonarteritic ischemic optic neuropathy includes the following features: (1) structurally crowded optic discs are predisposed; (2) laminar and retrolaminar regions are the most common locations for infarction; (3) there is flow impairment in the prelaminar optic disc during the acute phase; (4) lack of consistent choroidal flow impairment and the retrolaminar location of infarcts suggest vasculopathy within or distal to the paraoptic branches of the posterior choroidal arteries; (5) diabetes is the most consistently identified vasculopathic risk factor; (6) impaired autoregulation of the disc circulation by atherosclerosis, with a possible contribution from serotonin and endothelin-mediated vasospasm, may play a role; and (7) progression may be caused by secondary cell death after the initial ischemic insult or compression from cavernous degeneration and mechanical axonal distortion.

Influence of arterial hypertension and diet-induced atherosclerosis on macular drusen

PURPOSE

To evaluate whether development of macular drusen is influenced by experimentally induced chronic arterial hypertension and atherosclerosis.

METHODS

The prospective experimental study included 93 eyes of 51 elderly rhesus monkeys. The total study group was divided into groups with experimental arterial hypertension ( n=22), diet-induced atherosclerosis ( n=10), or both arterial hypertension and atherosclerosis ( n=29) and a control group without arterial hypertension or atherosclerosis ( n=32). Using color wide-angle fundus photographs taken at the beginning and the end of the study, age-related macular degeneration was graded by counting the number and estimating the mean size of drusen in the macular region.

RESULTS

In the monkeys with arterial hypertension, the count and area of the macular drusen and the change in number and size of macular drusen during the follow-up period were significantly ( P<0.05) higher than in the monkeys of the control group. Correspondingly, the count and size of macular drusen were significantly ( P<0.05) correlated with the duration of arterial hypertension. In contrast, monkeys with only atherosclerosis did not vary significantly ( P>0.10) from monkeys of the control group in number and size of drusen. The macular drusen parameters were statistically ( P>0.20) independent of the duration of atherosclerosis. Similarly, the atherosclerotic monkeys and the monkeys of the control group did not vary significantly ( P>0.30) in the change of the macular drusen parameters during the follow-up period.

CONCLUSIONS

Development of macular drusen as part of age-related macular degeneration in rhesus monkeys may be associated with experimentally induced arterial hypertension. It does not seem to be influenced by diet-induced atherosclerosis.

Ipsilateral recurrence of nonarteritic anterior ischemic optic neuropathy

PURPOSE

To report the prevalence of recurrence of nonarteritic anterior ischemic optic neuropathy (NA-AION) in the same eye and possible contributing risk factors.

DESIGN

Cohort study.

METHODS

SETTING

Institutional.

STUDY POPULATION

The study includes 594 consecutive patients (829 eyes) with a diagnosis of NA-AION and follow-up of at least two months after the onset of NA-AION, examined in the Ocular Vascular Clinic since 1973. Simple progression of visual loss during an episode of NA-AION was not considered a fresh episode. INTERVENTION OR OBSERVATION PROCEDURES: Every patient had ophthalmic evaluation, including visual acuity, visual fields with a Goldmann perimeter, intraocular pressure, and slit lamp and ophthalmoscopic evaluation at initial visit and at each follow-up visit. The patients also had systemic evaluation; some patients had echocardiography (166 patients) and 24-hour ambulatory blood pressure (BP) monitoring-the latter was investigated in 80 patients (17 with and 63 without recurrence of NA-AION) who consented to participate in this study which was started in 1989. While optic disk edema was present, the patients were followed every 2 to 3 weeks. Once the optic disk edema resolved, they were followed up after 3 months, 6 months, and then at yearly intervals unless they had some new visual complaint.

MAIN OUTCOME MEASURES

Prevalence of a fresh episode of NA-AION in the same eye, and comparison of ocular and systemic risk factors between patients with and without recurrence of NA-AION in the same eye.

RESULTS

Of the 594 patients (829 eyes) in the study, recurrence of NA-AION in the same eye occurred in 45 patients (53 eyes) with a median follow-up of 3.1 years (range 2 months to 30.5 years) from the first onset of NA-AION. The Kaplan-Meier survival curve showed cumulative percentage of recurrence of NA-AION from first episode to second episode at three months 1.0%+/-0.4%(SE), at 6 months 2.7%+/-0.7%, at one year 4.1%+/-0.9%, and 2 years 5.8%+/-1.1%. There was no significant association between recurrence of NA-AION and the systemic conditions that were examined, except for nocturnal arterial hypotension. Overall patients with a recurrence of NA-AION had a significantly lower mean nighttime minimum diastolic BP (P =.003) and greater mean percentage drop during sleep in diastolic BP (P =.011) than those with no recurrence of NA-AION; all other measures of nocturnal hypotension were not significantly predictive.

CONCLUSIONS

Recurrence of NA-AION in the same eye is uncommon (6.4%). Our study indicates that nocturnal diastolic arterial hypotension may be a risk factor; however, since this is a multifactorial disease, other so far unknown risk factors may also play a role. The role of various risk factors which may contribute to the recurrence of NA-AION is discussed.

The blood supply of the optic nerve head and the evaluation of it - myth and reality

Evidence has gradually emerged that there is vascular insufficiency in the optic nerve head (ONH) in both anterior ischemic optic neuropathy (AION) and glaucomatous optic neuropathy (GON); thus both represent ischemic disorders of the ONH. Together these diseases constitute a major cause of blindness or seriously impaired vision in man. Consequently there has recently been great interest in the ONH circulation in health and disease and in how to evaluate it. Many studies of the subject have been published, with conflicting interpretations and claims. The basis of the inconsistent information seems to be confusion on some fundamental issues concerning the ONH circulation itself. The objective of this paper is to differentiate myths and misconceptions from reality about the ONH blood supply; to elucidate the reasons for disagreement on the blood supply of the ONH; and to evaluate the reliability and validity of various methods currently used to measure ONH blood flow.

Blood flow in the optic nerve head and factors that may influence it

In the recent past there has been great interest in the blood supply of the optic nerve head (ONH), how to evaluate ONH blood flow, and what factors influence it, in health and disease. This is because evidence has progressively accumulated that there is vascular insufficiency in the ONH in both anterior ischemic optic neuropathy (AION) and glaucomatous optic neuropathy (GON)-two major causes of blindness or of seriously impaired vision in man. For the management and prevention of visual loss in these two disorders, a proper understanding of the factors that influence the blood flow in the ONH is essential. The objective of this paper is, therefore, to review and discuss all these factors. The various factors that influence the vascular resistance, mean blood pressure and intraocular pressure are discussed, to create a better basic understanding of the ONH blood flow, which may help us toward a logical strategy for prevention and management of ischemic disorders of the ONH.

Anterior ischemic optic neuropathy associated with viagra

A 42-year-old male presented with acute onset of an inferior visual field defect OD after sildenafil citrate use. Examination revealed a right relative afferent pupillary defect and a swollen disc with a 0.1 cup-to-disc ratio and a prominent disc hemorrhage. Anterior ischemic optic neuropathy (AION) is associated with acute episodes of hypotension in patients with structurally crowded discs. Sildenafil citrate may cause episodes of hypotension and was temporally related to the onset of symptoms in this patient. Because patients are often reluctant to volunteer their history of sildenafil citrate use, the physician may need to ask specifically about use of this medication. Physicians should counsel patients with crowded optic discs and a history of nonarteritic anterior ischemic optic neuropathy in one eye that use of sildenafil citrate might increase their risk of ischemic optic neuropathy in the fellow eye.