The distribution of toxic metals in the human retina and optic nerve head: Implications for age-related macular degeneration.

OBJECTIVE:Toxic metals are suspected to play a role in the pathogenesis of age-related macular degeneration. However, difficulties in detecting the presence of multiple toxic metals within the intact human retina, and in separating primary metal toxicity from the secondary uptake of metals in damaged tissue, have hindered progress in this field. We therefore looked for the presence of several toxic metals in the posterior segment of normal adult eyes using elemental bioimaging. METHODS:Paraffin sections of the posterior segment of the eye from seven tissue donors (age range 54-74 years) to an eye bank were examined for toxic metals in situ using laser ablation-inductively coupled plasma-mass spectrometry, a technique that detects multiple elements in tissues, as well as the histochemical technique of autometallography that demonstrates inorganic mercury, silver, and bismuth. No donor had a visual impairment, and no significant retinal abnormalities were seen on post mortem fundoscopy and histology. RESULTS:Metals found by laser ablation-inductively coupled plasma-mass spectrometry in the retinal pigment epithelium and choriocapillaris were lead (n = 7), nickel (n = 7), iron (n = 7), cadmium (n = 6), mercury (n = 6), bismuth (n = 5), aluminium (n = 3), and silver (n = 1). In the neural retina, mercury was present in six samples, and iron in one. Metals detected in the optic nerve head were iron (N = 7), mercury (N = 7), nickel (N = 4), and aluminium (N = 1). No gold or chromium was seen. Autometallography demonstrated probable inorganic mercury in the retinal pigment epithelium of one donor. CONCLUSION:Several toxic metals are taken up by the human retina and optic nerve head. Injury to the retinal pigment epithelium from toxic metals could damage the neuroprotective functions of the retinal pigment epithelium and allow toxic metals to enter the outer neural retina. These findings support the hypothesis that accumulations of toxic metals in the retina could contribute to the pathogenesis of age-related macular degeneration

Intraocular solitary extramedullary plasmacytoma presenting as unilateral anterior and intermediate uveitis preceded by refractory glaucoma

Background: Solitary extramedullary plasmacytoma (SEP) is a localised proliferation of monoclonal plasma cells involving soft tissue with no or minimal bone marrow involvement and no other systemic evidence of multiple myeloma. Intraocular involvement is exceedingly rare. Case presentation: We report a 78-year-old man who was referred with glaucoma in the right eye. He subsequently developed anterior chamber (AC) inflammation and refractory glaucoma then dense vitritis. A vitrectomy was performed with the biopsy revealing numerous plasma cells with atypical findings. In conjunction with the flow cytometry results, and a systemic work up excluding multiple myeloma, a diagnosis of SEP was made. The patient was treated with ocular external beam radiotherapy with resolution of the intraocular inflammation and control of the intraocular pressure. He remains well with no local recurrence and no development of multiple myeloma over a follow up period of 2.5 years. Conclusions: This is the first case report of SEP presenting as intraocular inflammation without a uveal tract mass

Synthesis and propagation of complement C3 by microglia/monocytes in the aging retina

INTRODUCTION Complement activation is thought to contribute to the pathogenesis of age-related macular degeneration (AMD), which may be mediated in part by para-inflammatory processes. We aimed to investigate the expression and localization of C3, a crucial component of the complement system, in the retina during the course of aging. METHODS SD rats were born and reared in low-light conditions, and euthanized at post-natal (P) days 100, 450, or 750. Expression of C3, IBA1, and Ccl- and Cxcl- chemokines was assessed by qPCR, and in situ hybridization. Thickness of the ONL was assessed in retinal sections as a measure of photoreceptor loss, and counts were made of C3-expressing monocytes. RESULTS C3 expression increased significantly at P750, and correlated with thinning of the ONL, at P750, and up-regulation of GFAP. In situ hybridization showed that C3 was expressed by microglia/monocytes, mainly from within the retinal vasculature, and occasionally the ONL. The number of C3-expressing microglia increased significantly by P750, and coincided spatiotemporally with thinning of the ONL, and up-regulation of Ccl- and Cxcl- chemokines. CONCLUSIONS Our data suggest that recruited microglia/monocytes contribute to activation of complement in the aging retina, through local expression of C3 mRNA. C3 expression coincides with age-related thinning of the ONL at P750, although it is unclear whether the C3-expressing monocytes are a cause or consequence. These findings provide evidence of activation of complement during natural aging, and may have relevance to cellular events underling the pathogenesis of age-related retinal diseases.Funding provided by Australian Research Council Centres of Excellence Program Grant (CE0561903)

Myeloid cells expressing VEGF and arginase-1 following uptake of damaged retinal pigment epithelium suggests potential mechanism that drives the onset of choroidal angiogenesis in mice

Whilst data recognise both myeloid cell accumulation during choroidal neovascularisation (CNV) as well as complement activation, none of the data has presented a clear explanation for the angiogenic drive that promotes pathological angiogenesis. One possibility that is a pre-eminent drive is a specific and early conditioning and activation of the myeloid cell infiltrate. Using a laser-induced CNV murine model, we have identified that disruption of retinal pigment epithelium (RPE) and Bruch's membrane resulted in an early recruitment of macrophages derived from monocytes and microglia, prior to angiogenesis and contemporaneous with lesional complement activation. Early recruited CD11b(+) cells expressed a definitive gene signature of selective inflammatory mediators particularly a pronounced Arg-1 expression. Accumulating macrophages from retina and peripheral blood were activated at the site of injury, displaying enhanced VEGF expression, and notably prior to exaggerated VEGF expression from RPE, or earliest stages of angiogenesis. All of these initial events, including distinct VEGF (+) Arg-1(+) myeloid cells, subsided when CNV was established and at the time RPE-VEGF expression was maximal. Depletion of inflammatory CCR2-positive monocytes confirmed origin of infiltrating monocyte Arg-1 expression, as following depletion Arg-1 signal was lost and CNV suppressed. Furthermore, our in vitro data supported a myeloid cell uptake of damaged RPE or its derivatives as a mechanism generating VEGF (+) Arg-1(+) phenotype in vivo. Our results reveal a potential early driver initiating angiogenesis via myeloid-derived VEGF drive following uptake of damaged RPE and deliver an explanation of why CNV develops during any of the stages of macular degeneration and can be explored further for therapeutic gain

The in vivo correlation between retinal pigment epithelium thickness and quantitative fundus autofluorescence in a Caucasian population

Purpose: To investigate the influence of age on the thickness of the retinal pigment epithelium/Bruch's membrane complex (RPE/Bruch's complex) and the quantitative autofluorescence (qAF) and to study the possible correlation existing between these two parameters in a healthy Caucasian population. Design: cross-sectional, observational study PARTICIPANTS: Healthy Caucasian volunteers between 18 and 65 years of age METHODS: All subjects underwent Spectral Domain Optical Coherence Tomography (SD-OCT) and qAF imaging with Heidelberg HRA-Spectralis. SD-OCT images were analyzed using the inbuilt graph-based automatic segmentation algorithm for single retinal layers identification to assess RPE/Bruch's complex thickness in vivo. The thickness values of both inner and outer rings of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid, generated by the software using the "RPE" segmentation, were averaged to obtain a single RPE/Bruch's complex thickness value in each eye. Quantitative autofluorescence images were also evaluated using a dedicated software. The qAF values of eight subfields forming a ring centered onto the fovea were collected and averaged in order to obtain a single qAF value (qAF8) in each eye. The correlation between the RPE/Bruch's complex thickness, the qAF value and the age of the subjects was investigated. Main outcome measures: the in vivo correlation between RPE/Bruch's complex thickness and qAF RESULTS: A total of 105 eyes from 105 subjects (mean age 42.1\ub113.9 years, range 18-65) were included in the analysis. The mean RPE/Bruch's complex thickness significantly increased with age (r=0.33, P=0.0006). The values of qAF were also positively increased with age (P<0.0001). A significant correlation was found between qAF and RPE/Bruch's complex thickness (r=0.27, P=0.004). After adjusting for age, iris color and gender, the correlation remained significant only for subjects younger than 40 years of age (P=0.009). Conclusions: The RPE/Bruch's complex thickness increased with age in a healthy Caucasian population. A similar increase was found for qAF values. After adjusting for age and iris color, qAF and RPE/Bruch's complex thickness were still correlated in subjects younger than 40 years. The RPE/Bruch's complex thickness could reflect the lipofuscin/melanolipofuscin accumulation in normal subjects, adding great interest in RPE cell biology

Ultrastructural and clinical evidence of subretinal debris accumulation in type 2 macular telangiectasia

Aims: To describe subretinal debris found on ultrastructural examination in an eye with macular telangiectasia (MacTel) type 2 and on optical coherence tomography (OCT) in a subset of patients with MacTel type 2. Methods: Blocks from the mid-periphery and temporal perifovea of an eye with clinically documented MacTel type 2 were examined with electron microscopy (EM). Cases came from the Sydney centre of the MacTel project and the practices of the authors. Results: On EM examination, subretinal debris was found in the perifovea with accumulation of degenerate photoreceptor elements in the subretinal space. Despite the substantial subretinal debris, there was minimal retinal pigment epithelial (RPE) reaction. Focal defects were seen in the inner limiting membrane in the perifovea. Of the 65 Sydney MacTel project participants, three (5%) had prominent yellow material at the fovea. OCT revealed smooth mounds between the RPE and the ellipsoid region. The material was hyperautofluorescent. Conclusions: This study suggests that subretinal accumulation of photoreceptor debris may be a feature of MacTel type 2. Ultrastructural and OCT evidence of disease beyond the vasculature, involving photoreceptors and Muller cells, is presented.6 page(s

CUTICULAR DRUSEN: Risk of Geographic Atrophy and Macular Neovascularization

PURPOSE: Cuticular drusen (CD) have been associated with manifestations of age-related macular degeneration such as atrophy and neovascularization in the macula. In this study, eyes with CD were followed and investigated for the estimated 5-year risk of progression to sequelae of age-related macular degeneration such as geographic atrophy (GA) and macular neovascularization (MNV). METHODS: A consecutive series of patients with CD were followed for the development of GA and MNV. Whenever possible, they were also studied retrospectively. The patients with CD were categorized into three phenotypic groups. Phenotype 1: eyes had concentrated, densely populated CD in the macular and paramacular area, Phenotype 2: eyes showed scattered CD in the posterior fundus, and Phenotype 3: involved eyes with CD mixed with large drusen (\u3e200 µm). The 5-year incidence of progression was then estimated using a Kaplan-Meier estimator. RESULTS: A total of 63 eyes from 38 patients (35 women with a mean age at presentation of 58.9 ± 14.2 years) were studied and followed for a mean of 40 ± 18 months. Thirteen patients had single eyes with GA (84.5%; 11/13) or MNV (15.5%; 2/13) in one eye at presentation and were subsequently excluded. Geographic atrophy developed in 19.0% (12/63) of eyes and MNV in 4.8% (3/63) of eyes. The cumulative estimated 5-year risk of GA and MNV was 28.4% and 8.7%, respectively. The estimated 5-year incidence of MNV or GA was 12.6%, 50.0%, and 51.6% in Phenotype 1, Phenotype 2, and Phenotype 3, respectively (P = 0.0015, log-rank test). No difference in risk was found in the development of GA or MNV (P = 0.11) between the subgroup of patients presenting with GA or MNV in their fellow eye and those with both eyes included. CONCLUSION: When patients with CD are followed longitudinally, there was a significant risk of progression to GA or MNV for Phenotype 2 and Phenotype 3. Patients with CD are commonly first diagnosed in the fifth decade of life, and there is a female predominance. Clinicians should use multimodal imaging to detect and be aware of the risk of progression to manifestations of GA and MNV. These risks of GA and MNV suggest that patients with CD may be part of the overall spectrum of age-related macular degeneration