Association between laser flare photometry and symptom duration in primary rhegmatogenous retinal detachment.

PURPOSE: The purpose of this study was to investigate preoperative blood-ocular barrier disruption via laser flare photometry (LFP) in patients diagnosed with rhegmatogenous retinal detachment (RRD), and to analyse possible associations with symptom duration and anatomical parameters. METHODS: We retrospectively analysed consecutive patients presenting with RRD at a single centre between January 2016 and March 2020. LFP was performed in both eyes after pupillary dilatation prior to RRD surgery. Symptom duration, extent of retinal detachment, and lens status were assessed. For statistical analysis, we carried out the unequal variances t test and Welch's analysis of variance (ANOVA). RESULTS: We included 373 eyes of 373 patients (mean age 63.96 years ± 10.29; female:male ratio 1:1.8). LFP values quantified in photon count per millisecond (pc/ms) increased with longer symptom duration when comparing patients with a symptom duration of 0-3 days (n = 158; 9.25 ± 6.21 pc/ms) and ≥ 4 days (n = 215; 11.97 ± 11.58 pc/ms; p = 0.004). LFP values also rose with the number of retinal quadrants affected by RRD (1 quadrant, 6.82 ± 4.08 pc/ms; 2 quadrants, 10.08 ± 7.28 pc/ms; 3 quadrants, 12.79 ± 7.9 pc/ms; 4 quadrants, 31.57 ± 21.27 pc/ms; p < 0.001), macula off status (macula on, 8.89 ± 6.75 pc/ms; macula off, 12.65 ± 11.66 pc/ms; p < 0.001), and pseudophakic lens status (pseudophakia, 12.86 ± 9.52 pc/ms; phakia: 9.31 ± 9.67 pc/ms; p < 0.001). CONCLUSION: In RRD patients, blood-ocular barrier disruption quantified by LFP is associated with the duration of symptoms and the disease's anatomical extent. These results warrant further investigation of the potential clinical use of LFP in RRD.

Dynamic Observation: Immune-Privileged Microenvironment Limited the Effectiveness of Immunotherapy in an Intraocular Metastasis Mouse Model.

INTRODUCTION: Intraocular metastasis (IM) occurred in approximately 8-10% of patients with metastatic malignancy, for whom oncological immunotherapies showed poor visual potential. However, the mechanism for that inefficiency remains unclear and requires further exploration. METHODS: We established a novel mouse model of IM by intracarotid injection of cutaneous melanoma cells. We investigated disease progression using ophthalmic and histological examinations. We used combined anti-PD-1 and anti-CTLA4 antibodies for immunotherapy and evaluated the therapeutic effects in the mouse model. In addition, we characterized the immune microenvironment of tumor-infiltrating CD8+ T by fluorescence staining and assessed their cytotoxicity by flow cytometry. RESULTS: All mice presented IM in the left eye, while the right eye was healthy. Uveal tissues with rich vascularity (e.g., the iris, ciliary body, and choroid) initiated IM at an early stage, and IM development resulted in several secondary changes, including corneal swelling, retinal detachment, and intratumoral hemorrhage. Immunotherapy could inhibit IM and prolong the time to eye rupture but did not prevent rupture ending. This inefficiency might be attributed to ocular tissues specificities that inhibited CD8+ T-cell infiltration via PD-L1 expression. PD-L1low corneal tissue resisted tumor invasion with high levels of CD8+ T-cell infiltration, whereas CD8+ T cells were deficient in PD-L1high uveal metastasis. Furthermore, we found a significantly increased PD-1+/- CD4+ and PD-1+/- CD8+ T cells infiltrating the intratumoral hemorrhage area. Although these CD8+ T cells in the IM were not exhausted and had a higher capacity of cytotoxicity (higher interferon-γ ratio) than CD8+ T cells in the blood, FasL+ PD-L1+ ocular tissue can strongly inhibit these IM-infiltrating T cells. CONCLUSIONS: Immunotherapy can inhibit the disease progression of IM. Enhancing the effects of tumor-infiltrating CD8+ T cells should be one of the highest potentials to improve the visual potential.

Selective permeability of mouse blood-aqueous barrier as determined by 15N-heavy isotope tracing and mass spectrometry.

The blood-aqueous barrier plays a key role in regulating aqueous humor homeostasis by selectively restricting passage of proteins into the eye. The kinetics of aqueous flow are traditionally measured using artificial markers; however, these marker molecules do not address the barrier's selective permeability to plasma proteins. Here we applied stable isotope labeling of all serum proteins with nitrogen-15 (15N) atoms. Following systemic injection of this "heavy" serum in mice, the 15N-to-endogenous nitrogen-14 (14N) ratio of each protein in aqueous was measured by mass spectrometry. By monitoring the kinetic changes in these ratios, we determined the permeability profiles of hundreds of serum proteins. Meanwhile, we subjected one of the eyes to neoangiogenic wound healing by inflicting injury to the corneal limbus and compared the 15N proteomes between the normal eyes and the recovering eyes at 2 weeks after injury. In the injured eye, we detected markedly enhanced permeability to inhibitory complement regulator proteins, such as Cfh, Cfhr, Cfb, Cfi, Cfd, and Vtn. Many of the proteins in this group are implicated in age-related macular degeneration associated with leakage of the blood-retinal barrier due to inflammation. To rule out the possibility that the observed leakage was due simply to physical damage of the blood vessels, we separately created a neovascularization model using an alkali burn of the avascular cornea. In this latter model, elevated levels of Cfh and Cfb were evident. These findings suggest that ocular neovascularization is associated with enhanced permeability to serum complement regulators.

[Acute ocular lesions after exposure to electromagnetic radiation of ultrahigh frequency (an experimental study)]. / Ostroe porazhenie organa zreniia élektromagnitnym izlucheniem sverkhvysokochastotnogo diapazona (éksperimental'noe issledovanie).

PURPOSE: To investigate the clinical and morphological manifestations of ocular lesions resulting from acute exposure to microwave radiation (MR). MATERIAL AND METHODS: Twenty-four rabbits were included in the study and divided into four equal groups according to MR exposure time (15, 30, 45, 60 s). The right eyes of rabbits were exposed to MR of 3.97 GHz and energy density of 1.0 W/cm2. The sham control group consisted of six animals. The exposed (right) and the paired (left) eye were studied for clinical and morphological changes, content of proinflammatory cytokines IL-1ß, IL-6 and TNF-α in the anterior chamber and in the vitreous body after exposure to MR. RESULTS: Significant dose-dependent changes in the structure of the exposed eye were revealed. Formation of microwave cataract was noted at the MR exposure time of 15 seconds and more. Partial or complete de-epithelialization, stromal edema, endothelial damage and inflammatory infiltration in the cornea, effusion of protein and cellular reaction in the aqueous humor were detected after MR exposure of 30, 45 and 60 seconds. Cellular reaction in the vitreous body was observed after exposure time of 45 and 60 seconds. Exposure to MR for up to 1 minute did not lead to visible clinical or morphological (traditional methods of examination) damage of the retina and optic nerve within 24 hours. Significantly higher content of proinflammatory cytokines IL-1ß, IL-6 and TNF-α in the aqueous humor and vitreous body was revealed in animals exposed to MR for 45 and 60 seconds. CONCLUSION: Acute exposure of the organ of vision to electromagnetic microwave radiation can lead to adverse dose-dependent effects not only in the lens, but also in other structures of the eye.

Feline Infectious Peritonitis: Immunohistochemical Features of Ocular Inflammation and the Distribution of Viral Antigens in Structures of the Eye.

Feline infectious peritonitis (FIP) is a serious, widely distributed systemic disease caused by feline coronavirus (FCoV), in which ocular disease is common. However, questions remain about the patterns of ocular inflammation and the distribution of viral antigen in the eyes of cats with FIP. This study characterized the ocular lesions of FIP including the expression of glial fibrillary acidic protein and proliferating cell nuclear antigen by Müller cells in the retina in cases of FIP and to what extent macrophages are involved in ocular inflammation in FIP. Immunohistochemistry for FCoV, CD3, CD79a, glial fibrillary acidic protein, calprotectin, and proliferating cell nuclear antigen was performed on paraffin sections from 15 naturally occurring cases of FIP and from controls. Glial fibrillary acidic protein expression was increased in the retina in cases of FIP. Müller cell proliferation was present within lesions of retinal detachment. Macrophages were present in FIP-associated ocular lesions, but they were the most numerous inflammatory cells only within granulomas (2/15 cats, 13%). In cases of severe inflammation of the ciliary body with damage to blood vessel walls and ciliary epithelium (3/15, 20%), some macrophages expressed FCoV antigens, and immunolabeling for calprotectin on consecutive sections suggested that these FCoV-positive macrophages were likely to be recently derived from blood. In cases of severe and massive inflammation of most ocular structures (4/15, 26%), B cells and plasma cells predominated over T cells and macrophages. These results indicate that gliosis can be present in FIP-affected retinas and suggest that breakdown of the blood-ocular barrier can allow FCoV-bearing macrophages to access the eye.

Age-associated gadolinium leakage into ocular structures in patients with acute traumatic brain injury.

BACKGROUND: Gadolinium Leakage into Ocular Structures (GLOS) is common following acute cerebrovascular events. The objective of this study was to investigate the occurrence of GLOS in an acute traumatic brain injury (TBI) cohort without acute cerebrovascular injury and to explore associated factors. METHODS: Enrolled acute TBI patients had a baseline MRI ≤48 h of injury (TP1) and follow-up MRI ≤72 h after baseline (TP2). Vitreous chamber enhancement and signal intensity ratios (SIRs) were calculated using pre- and post-contrast Fluid Attenuated Inversion Recovery (FLAIR). White matter hyperintensities (WMHs) were assessed using the Fazekas scale. RESULTS: Of the 128 TBI patients included, median age was 47 years, 70% male, and 66% presented with Glasgow Coma Scale of 15. No GLOS was detected at TP1 but was present in 23% of patients at TP2. GLOS+ patients were older (68 years [56-76] vs 39 years [27-53], p < 0.001), more likely to report falls as injury mechanism (62% vs 36%, p = 0.006), report history of hypertension (41% vs 19%, p = 0.025), and had a higher burden of WMHs (59% vs 14% with a total Fazekas ≥2, p < 0.001). Quantitative SIRs confirmed qualitative assessments: GLOS+ patients had higher SIRs at TP2 (0.43 vs 0.22, p < 0.001). Age (OR 3.28, 95%CI [1.88-5.71], p < 0.001) and prior TBI history (OR 4.99, 95%CI [1.46-17.06], p = 0.010) were independent predictors of GLOS. When age was removed, total Fazekas score (OR 2.53, 95%CI [1.60-4.00], p < 0.001) was an independent predictor of GLOS. CONCLUSIONS: GLOS is primarily associated with age and may serve as another imaging marker of chronic vascular disease.

Association between Oral Active-Matrix Metalloproteinase-8 Levels and Subretinal Fibrosis among Wet Age-Related Macular Degeneration Patients.

PURPOSE: Periodontitis causes low-grade systemic inflammation and has been associated with elevated active-matrix metalloproteinase (aMMP-8) levels, blood-ocular barrier breakdown and a risk of wet age-related macular degeneration. To assess the association between aMMP-8 levels and macular status among patients with wet age-related macular degeneration (AMD). METHODS: Patients on anti-VEGF treatment for wet AMD were enrolled for oral aMMP-8 rinse test in Mehiläinen Private Hospital, Helsinki, Finland. Macular status was examined from spectral-domain optical coherence tomography (SD-OCT) scans by a medical retina specialist and aMMP-8 levels were analyzed with chairside point-of-care oral rinse (PerioSafe®) test and real-time quantitated by a dentist using the ORALyzer®- reader with a 10 ng/ml cut-off for aMMP-8 activity. RESULTS: Elevated aMMP-8 levels were found in 10 out of 32 patients. Age, gender, anti-VEGF (bevacizumab or aflibercept) distribution, cumulative number of anti-VEGF injections and treatment interval were comparable between patients with aMMP-8 levels below and above the point-of-care level. Macular status differed in regard to aMMP-8 activity; among patients with aMMP-8 levels below the point-of-care subretinal fibrosis was found in 6 out of 22 eyes, whereas among patients with aMMP-8 levels above the point-of-care subretinal fibrosis was found in 8 out of 10 eyes (p = 0.005). Respectively, the mean thickness of subretinal fibrosis at fovea was 19.5 ± 44.1 and 92.3 ± 78.3 µm (p = 0.018). No differences were found in the presence and in the area of geographic atrophy, or fluid distribution, whereas thicknesses of serous pigment epithelial detachment (65.5 ± 99.5 and 12.9 ± 27.9 µm, p = 0.038) and neuroretina (204.2 ± 57.8 µm and 143.0 ± 43.7 µm, p = 0.006) were greater in the eyes of patients with physiological aMMP-8 levels compared to those with elevated aMMP-8 levels. CONCLUSION: Elevated aMMP-8 levels may account for subretinal fibrosis formation in wet AMD.

Bilateral endogenous Serratia marcescens endophthalmitis secondary to endocarditis following cardiac surgery.

INTRODUCTION: Endogenous endophthalmitis is a sight-threatening condition caused by microorganisms crossing the blood-ocular barrier and inducing profound intraocular inflammation. CASE REPORT: A 65-year-old female experienced bilateral loss of vision after developing infective endocarditis as a complication of combined Bentall procedure and coronary artery bypass grafting. She was diagnosed with bilateral endogenous endophthalmitis secondary to Serratia marcescens. Despite aggressive treatment with intravitreal injections of antibiotics and steroids, intensive topical and systemic antibiotic therapy, there was permanent loss of sight in both eyes. CONCLUSION: The case highlights the importance of early recognition of the symptoms and signs of endogenous endophthalmitis in any patient with systemic infection by all clinicians and the necessity of prompt ophthalmological referral if a useful level of vision is to be preserved.

Association between periodontitis and blood-ocular barrier disruption.

PURPOSE: Periodontitis causes low-grade systemic inflammation e.g., through circulatory periodontal endotoxins, and it has been associated with cardiovascular morbidity and wet age-related macular degeneration. METHODS: To assess the association between clinical severity of periodontitis and aqueous flare levels in the eyes. Patients with periodontitis (N = 15) who underwent periodontal treatment by a specialized dentist between the years 2020 and 2021 at the Chin and Mouth Disease Unit, Kymenlaakso Central Hospital, Kotka, Finland were enrolled. Aqueous flare levels, a surrogate marker for blood-aqueous and blood-retinal-barrier disruption, were measured using Laser Flare Meter (FM-600, Kowa Company, Ltd., Nagoya, Japan) before and right after the periodontal treatment and at 3 months. The number of teeth, periodontal probing depth (PPD), periodontal pathogens and antimicrobial treatment were recorded. RESULTS: At baseline, aqueous flare levels correlated with the number of clinically-relevant PPD (>5 mm) pockets (R = 0.789, P < 0.001) and inversely correlated with the number of teeth (R = -0.587, P = 0.035). At baseline, aqueous flare levels were 15.39 ± 13.24 photon units (pu)/ms among patients with periodontal pathogens, compared with 3.29 ± 1.67 pu/ms among those without any peridontal pathogens in PCR (P = 0.018). At 3 months compared to baseline values, aqueous flare levels were reduced to <50% from baseline among 6 patients (40%), whereas the levels increased to >200% from baseline in 1 patient (7%) (repeated measures ANOVA, P < 0.026). CONCLUSIONS: Poor periodontal status was associated with blood-ocular-barrier breakdown. These findings could expand our understanding of the potential mechanisms and therapeutic targets against retinal vascular diseases and systemic comorbidities in patients with periodontitis.

Instrument-based tests for quantifying aqueous humour protein levels in uveitis: a systematic review protocol.

BACKGROUND: Inflammation in anterior uveitis is characterised by breakdown of the blood-ocular barrier, which allows leakage of blood constituents of higher molecular weight into the aqueous humour. In routine clinical care, increase in aqueous protein levels can be observed at the slit lamp as 'flare' and the severity can be graded using various clinical grading systems, of which the Standardization of Uveitis Nomenclature (SUN) grading system is most commonly used. Alternative instrument-based technologies are available, which can detect aqueous protein levels in an objective and quantifiable way. This review will identify instruments capable of measuring anterior chamber inflammation in this way, their level of reliability, and how well the measurements correlate with clinical grading and/or actual aqueous protein concentration. METHODS: Standard systematic review methodology will be used to identify, select and extract data from studies that report the use of any instrument-based technology in the assessment of aqueous protein levels. Searches will be conducted through bibliographic databases (MEDLINE, EMBASE and Cochrane Library), clinical trial registries and the grey literature. No restrictions will be placed on language or year of publication. The outcomes of interest are the level of correlation between identified instrument-based test measurements, clinical grading and/or actual aqueous protein concentration, as well as the reliability of each index test identified. Study quality assessment will be based on QUADAS2. Correlation and reliability outcomes will be pooled and meta-analysed if appropriate. DISCUSSION: The assessment of inflammation in anterior chamber protein levels currently relies on crude and subjective clinical examination. The findings of this review will identify non-invasive technologies which show good correlation with actual protein concentration, which could be used in routine clinical practice for objective monitoring of AC inflammation. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017084167. Study screening stage has just been completed.

Adult T-cell leukemia cell-induced uveitis: rapid increase in adult T-cell leukemia cells disrupts the blood-ocular barrier.

Adult T-cell leukemia-lymphoma (ATL), a rare lymphoid malignancy with a high mortality rate, is caused by the human T-cell leukemia virus type 1. Due to its rarity and poor prognosis, ocular manifestations have yet to be well documented. The mechanisms that underlie ocular involvement in ATL patients, thus, remain poorly understood. We report the first successfully tracked case of ocular inflammation (i.e., uveitis) that developed simultaneously in conjunction with a rapid increase in ATL cells. Our findings for this case suggest that a rapid increase in ATL cells contributed to the disruption of the blood-ocular barrier, which may, thus, represent one mechanism underlying the induction of uveitis in ATL patients. Furthermore, with the development of novel therapies, the longer survival times of ATL patients have raised new issues, such as quality of vision in ATL patients. Hematologists should be aware that a rapid increase in the number of ATL cells may cause adult T-cell leukemia cell-induced uveitis.

The autoimmune diseases of the eyes.

The eye is divided anatomically in three layers: an outer or fibrous layer (cornea/sclera), middle or vascular layer (uvea - iris, ciliary body, and choroid) and an inner or sensorineural layer (retina). They compose the several anatomic and functional layers that enable the immune protection of the eye. The first layer involves an intact anatomic border with the blood-ocular barrier and immunosuppressive neuropeptides in the native aqueous humor. The second layer trusts on the capability of the eye to reestablish an immunosuppressive micro-environment by activating latent TGF-ß and reestablishing the anterior chamber-associated immune deviation. The third layer involves a mechanism that is not yet completely recognized, but that has the ability to overcome a predominantly Th1 intraocular immune response and to reestablish anterior chamber-associated immune deviation. Understanding the comprehensive mechanisms of these pathways, will lead to the development of new treatments strategies in order to prevent damage to the eye from persistent or exacerbated inflammation, directed at first to pathogens, but that may develop an autoimmune reaction.

Expression of neonatal Fc receptor in the eye.

PURPOSE: The neonatal Fc receptor (FcRn) plays a critical role in the homeostasis and degradation of immunoglobulin G (IgG). It mediates the transport of IgG across epithelial cell barriers and recycles IgG in endothelial cells back into the bloodstream. These functions critically depend on the binding of FcRn to the Fc domain of IgG. The half-life and distribution of intravitreally injected anti-VEGF molecules containing IgG-Fc domains might therefore be affected by FcRn expressed in the eye. In order to establish whether FcRn-Fc(IgG) interactions may occur in the eye, we studied the mRNA and protein distribution of FcRn in postmortem ocular tissue. METHODS: We used qPCR to study mRNA expression of the transmembrane chain of FcRn (FCGRT) in retina, optic nerve, RPE/choroid plexus, ciliary body/iris plexus, lens, cornea, and conjunctiva isolated from mouse, rat, pig, and human postmortem eyes and used immunohistochemistry to determine the pattern of FcRn expression in FCGRT-transgenic mouse and human eyes. RESULTS: In all four tested species, Fcgrt mRNA was expressed in the retina, RPE/choroid, and the ciliary body/iris, while immunohistochemistry documented FcRn protein expression in the ciliary body epithelium, macrophages, and endothelial cells in the retinal and choroidal vasculature. CONCLUSIONS: Our results demonstrate that FcRn has the potential to interact with IgG-Fc domains in the ciliary epithelium and retinal and choroidal vasculature, which might affect the half-life and distribution of intravitreally injected Fc-carrying molecules.

Expression of the primary angle closure glaucoma (PACG) susceptibility gene PLEKHA7 in endothelial and epithelial cell junctions in the eye.

PURPOSE: The role of the recently identified primary angle closure glaucoma (PACG) susceptibility gene, pleckstrin homology domain containing, family A member 7 (PLEKHA7), in PACG is unknown. PLEKHA7 associates with apical junctional complexes (AJCs) and is thus implicated in paracellular fluid regulation. We aimed to determine PLEKHA7's localization in the eye and its association with AJCs to elucidate its potential role in PACG. METHODS: Total RNA from ocular tissues was isolated and analyzed by real-time PCR. Frozen and paraffin-embedded human globes were sectioned and used for immunohistochemistry and immunofluorescence analysis. RESULTS: Specific PLEKHA7 expression was found in the muscles, vascular endothelium, and epithelium of the iris, ciliary body and ciliary processes, trabecular meshwork (TM), and choroid. PLEKHA7 expression in musculature and vascular endothelium was confirmed with smooth muscle marker, SMA, and endothelium marker, PECAM-1, respectively. At the above sites, PLEKHA7 colocalization was seen with adherens junction markers (E-cadherin and ß-catenin) and tight junction markers (ZO-1). CONCLUSIONS: Specific localization of PLEKHA7 was found within PACG-related structures (iris, ciliary body, and choroid) and blood-aqueous barrier (BAB) structures (posterior iris epithelium, nonpigmented ciliary epithelium, iris and ciliary body microvasculature). The association of PLEKHA7 with AJCs in the eye suggests a potential role for PLEKHA7 in PACG via fluidic regulation. Novel expression of PLEKHA7 was also seen in the ocular smooth muscles and vascular endothelia.

Characterization of vitamin D production by human ocular barrier cells.

PURPOSE: Vitamin D3 is a secosteroid mainly synthesized from the conversion of the skin precursor 7-dehydrocholesterol (7DHC) to vitamin D3 by ultraviolet (UV) B sunlight. Extrarenal synthesis of vitamin D3 has been reported in many tissues and cells, including barrier sites. This study characterizes the expression of components of vitamin D3 signaling in human ocular barrier cells. METHODS: Primary human scleral fibroblasts (HSF), human corneal endothelial (HCEC-12), nonpigmented ciliary body epithelial (ODM-2), and adult retinal pigment epithelial (ARPE-19) cell lines were analyzed for the expression of vitamin D receptor (VDR), the vitamin D3 activating enzymes 1α-hydroxylase (CYP27B1), 25-hydroxylases (CYP27A1 and CYP2R1), the vitamin D3 inactivating enzyme 24-hydroxylase (CYP24A1), and the endocytic receptors cubilin and megalin using a combination of RT-PCR, immunocytochemistry, and enzyme immunoassay (EIA). RESULTS: The HSF, HCEC-12, ODM-2, and ARPE-19 express mRNA and protein for all vitamin D3 synthesizing and metabolizing components. The cell types tested, except HSF, are able to convert inactive 25-hydroxyvitamin D3 (25[OH]D3) into active 1,25-hydroxyvitamin D3 (1,25[OH]2D3). CONCLUSIONS: This novel study demonstrated that ocular barrier epithelial cells express the machinery for vitamin D3 and can produce 1,25(OH)2D3. We suggest that vitamin D3 might have a role in immune regulation and barrier function in ocular barrier epithelial cells.

Neisseria meningitidis endogenous endophthalmitis with meningitis in an immunocompetent child.

Neisseria meningitidis is a major cause of childhood morbidity and mortality worldwide. We describe an exceptional case of an immunocompetent 15-month-old child presenting with a unilateral anterior uveitis, hypopyon, and sepsis. Anterior chamber aspirate demonstrated gram-negative cocci before Neisseria meningitidis was identified in blood and cerebrospinal fluid. Meningococcal endophthalmitis presents variably with sepsis, meningitis, or isolated ocular symptoms. Diagnosis is a clinical challenge, requiring diagnostic sampling and treatment from both pediatricians and ophthalmologists. Delayed or incorrect treatment risks blindness, disability, or death. Simultaneous invasion of meningococcus across intact blood-brain and blood-ocular barriers in this child suggests antigenic correlates between meningeal and ocular endothelial interfaces. Meningococcus is an exclusively human pathogen; research is hampered by the lack of animal models. This clinical observation suggests the potential of a novel in vitro experimental approach of using ocular tissue from eye banks to further elucidate the meningococcal-endothelial interaction that underpins meningococcal disease.

Impact of P-glycoprotein on blood-retinal barrier permeability: comparison of blood-aqueous humor and blood-brain barrier using mdr1a knockout rats.

PURPOSE: The purpose of this study was to clarify the impact of P-glycoprotein (P-gp) on blood-retinal barrier (BRB) and blood-aqueous humor barrier (BAB) permeability, in contrast to blood-brain barrier (BBB) permeability. METHODS: Permeabilities of six compounds, including P-gp substrates (quinidine, digoxin, and verapamil), were investigated in wild-type and mdr1a knockout rats using retinal, aqueous humor, and brain uptake index (RUI, AHUI, and BUI, respectively) methods and integration plot analysis. RESULTS: In both rat strains, quinidine, digoxin, and verapamil were transported by P-gp across each barrier; however, the impact of P-gp on retinal uptake of quinidine and verapamil was less pronounced than that on brain uptake. The apparent influx permeability clearance (Kin) values of verapamil in retina obtained from wild-type and knockout rats were similar (0.824 ± 0.201 and 0.849 ± 0.980 mL/min·g retina, respectively; mean ± SD; n = 3 rats). The Kin in aqueous humor and brain obtained from knockout rats was, respectively, 3-fold and 12-fold higher than that of wild-type (P < 0.05). In P-gp-deficient conditions, the RUI and AHUI of quinidine, digoxin, and verapamil, as well as the BUI of quinidine and digoxin, were decreased by P-gp inhibitors. However, the BUI of verapamil was not changed by P-gp inhibitors. Results suggest that carrier-mediated influx transporters exist in the blood-ocular barriers and that the function of verapamil influx transporters is markedly different between the retina and brain. CONCLUSIONS: In both rat strains, P-gp operates in the blood-ocular barriers, and the impact of P-gp on BRB permeability to quinidine and verapamil is lower than that on BBB permeability.

Study on blood-ocular barrier between the anterior and posterior chamber after peripheral iridectomy by contrast-enhanced magnetic resonance in rabbit / 中华实验眼科杂志

Background Whether ocular anterior and posterior chamber exist a blood-aqueous barrier is in controversy.Conventional method can not offer a good evidence because it is unable to detect the aqueous component in the posterior chamber.Objective This study was to investigate the distribution of Gadolinium-diethylene triamine pentaacetic acids(Gd-DTPA)after peripheral iridectomy with magnetic resonance imaging(MRI)in rabbit.Methods Monocular peripheral iridectomy was performed on the right eyes in 8 clean New Zealand white rabbits and the fellow eyes were as controls.0.2 ml/kg(0.5 mol/L)Gd-DTPA,a tracer of MRI,was injected into ear vein in vivo to scan the eyes with MRI for the observation of the permeability and distribution.The signal enhanced ratio of interest region associated with time were analyzed.Results The signal in ciliary body of both eyes showed an immediately sharp enhancement within 10 minutes following the injection of Gd-DTPA with a peak intensity at 30-40 minutes,and then the intensity was gradually weaken over time.The signal was stronger in the operative eyes than that in the fellow eyes.The signal in the posterior chamber was gradually increased after operation,however,that in posterior chamber of the control eyes was lower.The interest regions of Gd-DTPA were ciliary,anterior chamber and posterior chamber,and the enhanced signal intensities were consisted in the posterior chamber after operation.However,the increase of the signal was not seen in the posterior chamber in the control eyes.Conclusions The pathway of plasma protein entering into the anterior chamber is very different from that of aqueous secretion.There exists a barrier between the anterior and posterior chamber which might be an integral part of the blood-ocular barrier.

The Steroid Effect on the Blood-Ocular Barrier Change Induced by Triolein Emulsion as seen on Contrast-Enhanced MR Images

OBJECTIVE: The purpose of this study is to evaluate the effect of dexamethasone on the damaged blood-ocular barrier caused by triolein emulsion, using contrast-enhanced MR imaging. MATERIALS AND METHODS: An emulsion of 0.1-mL triolein in 20 mL of saline was infused into the carotid arteries of 32 cats, 12 cats were placed in the treatment group and 18 cats were placed in the Control group. Thirty minutes after the infusion of triolein emulsion, a set of orbital pre- and post-contrast T1-weighted MR images (T1WIs) were obtained. Infusion of 10 mg/kg dexamethasone into the ipsilateral carotid artery of each of the cats in the treatment group cats and 20 mL saline in each of the cats in the control group was given. A second set of pre- and post-contrast orbital T1WIs were obtained three hours following triolein emulsion infusion. Qualitative analysis was performed for the the anterior chamber (AC), the posterior chamber (PC), and in the vitreous humor of the ipsilateral and contralateral eyes. The signal intensity ratios of the ipsilateral eye over the contralateral eye were quantitatively evaluated in the three ocular chambers on the first and second set of T1WIs, and were then statistically compared. RESULTS: Qualitatively, the AC, the PC or the vitreous did not show immediate contrast enhancement on the first and the second set of post-contrast T1WIs. However, the AC and the PC showed delayed contrast enhancement for both groups of cats on the second pre-contrast T1WIs. No enhancement or minimally delayed enhancement was seen for the vitreous humor. Quantitatively, the signal intensity ratios in the PC of the treatment group of cats were statistically lower than the ratios of the control group of cats for the second set of T1WIs (p = 0.037). The AC and vitreous showed no statistically significant difference between the feline treatment group and control group (p > 0.05). CONCLUSION: Contrast-enhanced MR images revealed increased vascular permeability in the PC of the eye after infusion of triolein emulsion. Dexamethasone seems to decrease the breakdown of the blood-aqueous barrier in the PC.