Outer Choroid Research Articles

Association between Complement Factor H Gene Polymorphisms and Neovascular Age-Related Macular Degeneration in Koreans

This study was undertaken to investigate the association between the complement factor H (CFH) gene and exudative age-related macular degeneration (AMD) in Korean patients. Genomic DNA was isolated from the peripheral leukocytes of patients with exudative AMD (n = 114) and control subjects (n = 187). The sole criterion for exudative AMD was the presence of choroidal neovascularization. Four single-nucleotide polymorphisms (SNPs: -275C>T, I62V, Y402H, and IVS15) located in promoter, exon 2, exon 9, and intron 15 of the CFH gene were genotyped by PCR-based direct sequencing. The frequency of the C allele of Y402H (AMD, 10.5%; control, 6.5%) was found to be lower in Koreans than in Caucasians. In the present study, the difference between the frequencies of Y402H in cases and control subjects did not reach statistical significance (P = 0.071). However, the frequencies of the major alleles of three SNPs (-275C>T, I62V, and IVS15) were significantly different in patients and control subjects, and these SNPs were found to be separately associated with an elevated risk of exudative AMD. Seven haplotypes were identified in Koreans. Haplotype analysis showed that two haplotypes (TGTG, CGTG) conferred significantly higher risks of exudative AMD (P = 0.013, 0.035), and one haplotype (CATA) was significantly protective (P < 0.001). In Korean subjects, CFH polymorphism appears to be a considerable hereditary contributor to exudative AMD. Y402H polymorphism which has been suggested to be a major risk factor of AMD in Caucasians was found to be only marginally associated with exudative AMD with low frequency, whereas three adjacent SNPs in the CFH gene were significantly associated with AMD in Koreans.

Choroidal neovascularization in peripapillary acute zonal occult outer retinopathy.

Acute zonal occult outer retinopathy (AZOOR) is a disease of unknown etiology in young or middle-aged patients that is characterized by acute loss of one or more zones of outer retinal function, photopsia, minimal initial ophthalmoscopic changes, and electroretinographic abnormalities. AZOOR may represent part of the spectrum of a single disease, the so-called AZOOR complex. In contrast with most other ocular diseases that may be part of this AZOOR complex, AZOOR has not, to our knowledge, been reported in association with choroidal neovascularization (CNV). We describe a 47-year-old man presenting with peripapillary AZOOR and CNV. Despite photodynamic therapy, CNV evolved to a fibrovascular diskiform scar. The occurrence of CNV on the margin of the AZOOR process suggested a direct link between the CNV and the underlying condition. To our knowledge, this is the first reported case of CNV complicating AZOOR.

Divergent Distribution in Vascular and Avascular Mammalian Retinae Links Neuroglobin to Cellular Respiration

The visual function of the vertebrate retina relies on sufficient supply with oxygen. Neuroglobin is a respiratory protein thought to play an essential role in oxygen homeostasis of neuronal cells. For further understanding of its function, we compared the distribution of neuroglobin and mitochondria in both vascular and avascular mammalian retinae. In the vascular retinae of mouse and rat, oxygen is supplied by the outer choroidal, deep retinal, and inner capillaries. We show that in this type of retina, mitochondria are concentrated in the inner segments of photoreceptor cells, the outer and the inner plexiform layers, and the ganglion cell layer. These are the same regions in which oxygen consumption takes place and in which neuroglobin is present at high levels. In the avascular retina of guinea pig the deep retinal and inner capillaries are absent. Therefore, only the inner segments of the photoreceptors adjacent to choroidal capillaries display an oxidative metabolism. We demonstrate that in the retina of guinea pigs both neuroglobin and mitochondria are restricted to this layer. Our results clearly demonstrate an association of neuroglobin and mitochondria, thus supporting the hypothesis that neuroglobin is a respiratory protein that supplies oxygen to the respiratory chain.

Cancer-associated Nummular Loss of the Pigment Epithelium

To report a case of bilateral diffuse uveal melanocytic proliferation (BDUMP) that had areas of retinal pigment epithelial loss. Observational case report. A 67-year-old woman with a history of uterine cancer presented with 4 months of bilateral visual loss. Although B-scan ultrasonography revealed both small shallow serous retinal and choroidal detachments in the periphery, the choroid was normal in thickness. Fluorescein angiography revealed numerous nummular-shaped areas of transmission defects suggesting retinal pigment epithelium loss. Autofluorescence photography showed complete absence of autofluorescence in these nummular areas, and optical coherence tomography showed segmental areas with lack of any signal from affected areas of the retinal pigment epithelium, suggesting complete loss of retinal pigment epithelium cells. Although the fundus findings in BDUMP have been attributed to the proliferation of uveal melanocytic cells in the outer choroid in previous papers, our patient had nummular areas of loss of the retinal pigment epithelium as the apparent reason for visual decline.

The human choriocapillaris: evidence for an intrinsic regulation of the endothelium?

The aim of the present study was to describe the ultrastructure of particular cells observed in the microvascular bed of the healthy human choroid, in close relation to the wall of the microvessels and resembling the periadventitial cells of other vascular areas of the human body. Serial sections of 12 fresh human eyes were studied by transmission electron microscopy. In all the eyes, the sections were obtained by cutting from the same zones (inner and outer choroid at the posterior pole of the eye). Standard techniques were used for transmission electron microscopy. Round cell bodies were found in the inner choroid at the posterior pole of the eye, mainly located in the intercapillary connective tissue. The cells were composed of an electron-transparent cytoplasm containing a few small mitochondria, and a dilated smooth surface of endoplasmic reticulum, at some points continuous with the nuclear membrane. These cells showed processes forming contact with the capillary wall. Some of these processes extended to the elastic layer of Bruch's membrane, but none had contact with the retinal pigment epithelium. A thin basement membrane surrounded both the cell bodies and processes. We believe that these cells are special cells resembling some type of periendothelial cells also localized in other microvascular districts of the human body. The close topographic correlation with the endothelial cells seems to indicate that these special cells play a role in the intrinsic control of proper endothelial functions.

Choroidal ganglion cell changes in human glaucomatous eyes.

Choroidal ganglion cells (CGC) are an important source of vasodilative innervation of the posterior ciliary arteries, which also supplies the lamina cribrosa region of the optic nerve. The purpose of this study was to investigate whether CGC undergo quantitative and morphologic changes in human glaucomatous eyes. Twenty-five human glaucomatous eyes (15 with primary open angle glaucoma, 10 with pseudoexfoliation glaucoma) and 38 normal eyes (31 age-matched) were investigated. Scleral and choroidal whole mounts were stained for NADPH diaphorase, the CGC quantified in the outer and inner choroid and in the different quadrants separately, and the diameter of the CGC measured. Serial semi- and ultrathin sections were studied by light and electron microscopy. In glaucomatous eyes, the total number of CGC was significantly decreased. The most striking loss of CGC was found in the temporal quadrant adjacent to the optic nerve, where only single CGC persisted. The remaining CGC showed a normal ultrastructural appearance but a shift toward larger cells. Smaller CGC and those directly adjacent to the optic nerve seem to be most susceptible to the yet unknown pathogenetic factors responsible for this CGC loss. Since the most pronounced loss of CGC occurred in the vicinity of the optic nerve it is tempting to speculate that the vasodilative regulation of the vessels supplying the lamina cribrosa region is impaired in eyes with POAG.

Expression and signification of pigment epithelium-derived factor in experimental choroidal neovascularization of rat

To investigate the expression and signification of pigment epithelium-derived factor in choroidal neovascularization (CNV) induced by krypton laser on Brown Norway rat. Five groups of 30 rats were photocoagulated by krypton laser in single eye to induce CNV. 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks after photocoagulation, The retina was processed for histopathology, in situ hybridization of PEDF mRNA, immunohistochemistry of PEDF and FVIIIR:Ag. CNV was formed 1 week after photocoagulation, and reached its peak at 3 weeks. PEDF mRNA, PEDF expressed in the ganglion cells, inner nuclear layer, retinal pigment epithelial cells in normal BN retina. After photocoagulation, the expression of PEDF mRNA and PEDF was observed in the ganglion cells, inner nuclear layer, retinal pigment epithelial cells, and the lesions of outer nuclear layer and choroid; the expression of PEDF in the lesions was weaker than that at the edge of the lesions. From 3 days to 4 weeks, the expression density of FVIIIR:Ag gradually increased, however, the expression density of PEDF mRNA and PEDF in the lesions decreased (P < 0.05). The expression of FVIIIR:Ag was inversely correlated with that of PEDF during the development of CNV (r = -0.84, P < 0.05). CNV is inversely correlated with PEDF. The down-regulation of PEDF may be one of the main reasons for the formation and development of CNV.

The Role of Aging, High Fat Diet and Blue Light Exposure in an Experimental Mouse Model for Basal Laminar Deposit Formation

We sought to investigate the role of aging as a susceptibility factor for the capacity of dietary fat intake to increase the development of subretinal deposits. Mice of various ages (2, 9 and 16 months) were fed a normal diet or a diet high in saturated and unsaturated fats for a total four and a half months. Some eyes were also exposed to non-phototoxic levels of blue-green light. The outer retina and choroid were examined by light and transmission electron microscopy, and the characteristics, frequency and severity of subRPE deposits was determined. Aged mice fed normal diets developed only very mild subretinal deposits. However, many eyes of mice aged 9 months or older at the time of initiation of diet developed frequent basal laminar deposits of moderate severity, and only 16 month old mice developed more severe deposits after exposure to blue-green light. Some eyes in this older group also developed endothelial invasion into Bruch's membrane. None of the eyes developed classic drusen or linear deposits. These observations demonstrate that age increases the capacity of dietary fat, especially in the presence of environmental light, to induce subRPE deposits.

Temporal and spatial patterns of c-fos mRNA induced by intravenous interleukin-1: a cascade of non-neuronal cellular activation at the blood-brain barrier.

Brain cells responsive to a peripheral immune challenge, identified by in situ hybridization of c-fos mRNA following intravenous administration of the proinflammatory cytokine interleukin-1beta (IL-1) or sterile saline, were investigated at 0.5, 1, and 3 hours postinjection in rats. Doses of IL-1 ranged from 0.05 to 10 microg/kg; induction of c-fos mRNA occurred at > or = 0.5 pg/kg. The majority of IL-1-induced c-fos mRNA-positive cells were non-neuronal cells located in barrier regions of the brain. The cells became radiolabeled in two separate but related spatiotemporal patterns. The first pattern, occurring at 0.5 hour, was characterized by c-fos mRNA labeling of cells of the outer meninges (mainly arachnoid), blood vessels (arteries, veins, and capillaries), and choroid plexus. This activation pattern disappeared at 1 hour. At 3 hours, a second activation pattern appeared in cells located just inside the now quiescent barrier cells. In addition, the circumventricular organs each showed characteristic spatiotemporal labeling patterns resulting from successive activation of specific cell types, with a general spread of activation directed away from the circumventricular organs over time. At 3 hours post IL-1, c-fos and glial fibrillary acidic protein (GFAP) mRNAs showed colocalization in the arcuate nucleus/median eminence/glia limitans region. We propose that the first wave of activation is elicited by blood-borne immune signals, but the second wave is caused by molecules generated within the first set of activated cells. The transduced signal appears to propagate to neighboring receptive cells by extracellular diffusion. In this manner, blood-brain barrier cells can transduce peripheral IL-1 signals in widespread areas of the brain, although the circumventricular organs may be the most effective loci for signal transduction.

Immunocytochemical study of retinal diode laser photocoagulation in the rat.

To determine the nature of the cellular infiltrate, alterations in cell adhesion molecules, and MHC II antigen expression in the rat retina following diode laser retinal photocoagulation. 20 normal Lister rats underwent diode laser photocoagulation of the retina. Frozen sections from eyes enucleated at 0, 1, 5, 13, and 33 days post laser were examined for T cells (R7.3), CD4 T cells (W3/25), activated CD4 T cells (OX-40), CD8 T cells (OX-8), B cells (OX-33), and macrophages (OX-42), MHC II antigen (OX-6), and E-Selectin-1, VCAM-1, and ICAM-1. Retinal diode laser photocoagulation stimulated a wound healing response in the outer retina and choroid. The cellular infiltrate included macrophages and activated CD4 T cells at 13 and 33 days post laser. Glial cells in the inner plexiform and inner nuclear layers expressed MHC II antigen at 24 hours only. ICAM-1 antigen was induced in RPE cells and in Muller cells in the inner retina at all time intervals post laser and intense staining for ICAM-1 was present around intraretinal migrated cells at 13 and 33 days post laser. VCAM-1 antigen expression was induced in the choroidal vascular endothelium and RPE at 13 and 33 days after laser as was E-Selectin-1 antigen expression which was also evident focally at the external limiting membrane in association with migrated cells adjacent to the burn. These results suggest that alterations in cell adhesion molecules may regulate the migration and activation of retinal pigment epithelium, macrophages and CD4 T cells at the outer blood-retinal barrier and choroid following diode laser photocoagulation of the normal Lister rat retina.

Birdshot retinochoroidopathy

Birdshot retinochoroidopathy is a rare bilateral ocular disorder which typically affects healthy, middle-age caucasians. The typical symptoms are recent onset of bilateral floaters with decreased vision in a white and quiet eye. Minimal anterior chamber reaction, vitreous infiltration without snowballs, and multifocal depigmented lesions in the outer retina and choroid are characteristic of birdshot retinochoroidopathy. Other associated findings include retinal vasculitis, paravascular hemorrhage, vitreous hemorrhage, cystoid macular edema, cellophane maculopathy, posterior subcapsular cataract, optic disc edema, vascular attenuation and tortuosity, optic atrophy and retinal or choroidal neovascularization. Management involves Amsler grid self-assessment and routine funduscopic examinations. A recently documented case of treatment with aromatic retinoids showed improvement while many other commonly prescribed medications are equivocal in effect. Laser photoablation or panretinal photocoagulation are recommended for treatable choroidal or retinal neovascularization, respectively.

A role for photoreceptor outer segments in the induction of deprivation myopia

An ultrastructural examination of the outer retina and choroid of hatchling chicks reared for periods of 1, 2 or 4 weeks with opaque occluders (MD) covering one eye, was instigated to elucidate the mechanism of deprivation myopia. Refractive myopia (approximately 20 D), retinal and choroidal thinning were induced in all deprived eyes. Electron microscopy showed significant changes in the MD eyes compared to normals. Cone inner segments were markedly thicker and outer segment lamellae more damaged. The rod outer segments were elongated and thicker than normal, such that their distal tips either directly apposed the basal lamina of the retinal pigment epithelium, or indented the cell nuclei. We hypothesize that this "rod-push" mechanism leads to thinning of the choroid in deprived eyes, and may directly contribute to axial myopia.

Pilot Trial of Transscleral Diode Laser Retinopexy in Retinal Detachment Surgery

The pilot study of transscleral diode laser retinopexy by Haller et al, 1 published in the July 1993 issue of theArchives, showed the feasibility of transscleral retinopexy during retinal detachment surgery. The treatments were called effective and safe, yet the energies used were high and choroidal rupture occurred in 30% of eyes. Effectivity. If the target tissue is the pigment epithelium, then the transscleral radiation has to pass through choroid. However, the outer choroid is maximally pigmented and considerable absorption takes place before light reaches the pigment epithelium. Large amounts of energy are required to penetrate the choroid. The figures in the article by Haller et al 1 demonstrate the extensive choroidal necrosis and atrophy and Table 1 shows energies to be in the range of 74 to 1492 J, with a mean energy of 520 J. 1 It is of note that five of the eyes in the

Distribution and characterisation of rat choroidal mast cells.

Despite the implication that choroidal mast cells are involved in the onset of experimental autoimmune uveoretinitis (EAU), a widely used animal model of uveoretinitis, little is known of these cells. In the present study the distribution, total number, regional density, and phenotype of choroidal mast cells were examined in Lewis, Wistar Furth, PVG/c, and brown Norway rats. Choroidal mast cells were predominantly associated with arteries and arterioles of more than 30 microns diameter which lie in the outer (sclerad) choroid. The density of mast cells was greatest in the posterior choroid with density diminishing anteriorly. The choroid of male Lewis rats contained significantly greater number of mast cells than that of females (p < 0.01). Histochemical (Alcian blue/safranin) and immunohistochemical (anti-rat mast cell protease I and II monoclonal antibodies) studies revealed choroidal mast cells were of the connective tissue type. However, granule proteinase content appeared less than that of well characterised connective tissue mast cell populations such as those in mesentery and skin. Lewis rats exhibited the highest density of choroidal mast cells (23.6 (SD 1.2)/mm2), Wistar Furth approximately half that of Lewis (13.5 (0.7)/mm2) while PVG/c and brown Norway rats had very low densities (3.06(0.3); 1.95(0.2/mm2 respectively). These studies provide valuable choroidal mast cell data for rats which may have implications for our understanding of experimental models of intraocular inflammation and clinical uveitis.

Bilateral Diffuse Uveal Melanocytic Proliferation in Patients With Occult Carcinoma

The development of multiple, round or oval, subtle, red patches at the level of the pigment epithelium in the posterior ocular fundus and their striking early hyperfluorescence angiographically are characteristic features of the bilateral diffuse uveal melanocytic proliferation syndrome. They may be accompanied by severe visual loss and may antedate the appearance of multiple melanocytic tumors, retinal detachment, and cataract in these patients with occult systemic carcinomas. These hyperfluorescent patches are caused by focal damage to the pigment epithelium overlying an intact choriocapillaris and diffuse benign nonpigmented uveal melanocytic infiltration of the outer choroid. We suggest that outer retinal damage may not be primarily caused by melanocytic proliferation, but rather by toxic and immune factors generated by interaction between a systemic carcinoma and congenital melanocytosis of the uveal tract. We report the longest survivor of this disorder to date (102 months).

Sorsby's Fundus Dystrophy: A Clinical Study

A survey was undertaken of a family known to have Sorsby's fundus dystrophy. Fifty members were reviewed, and 14 were found to be affected. Many of Sorsby's original conclusions were confirmed, including the pattern of inheritance and age of visual loss. Yellow material was present at the level of Bruch's membrane early in the course of the disease. However, the earliest phenotypic marker was delayed filling of the choriocapillaris. Abnormalities of choroidal perfusion became more profound and extended centrifugally with time. The loss of central vision was commonly due to atrophy of the outer retina and choroid. Subretinal neovascularization was a rare occurrence. The homology between this dystrophy and age-related macular disease underlines the importance of the clinical findings in this family.

Extracellular Modulating Factors and the Control of Intraocular Neovascularization

Neovascularization plays an important role in the pathogenesis of a number of ophthalmic disorders, including proliferative diabetic retinopathy and age-related macular degeneration. 1 Clinical studies have demonstrated that disruption (usually induced by laser) and subsequent repair of the outer retina and choroid can alter the course of both preretinal and subretinal neovascularization in many cases. Traditionally, investigators have conceptualized these events in physical terms—ischemic retina is obliterated or subretinal vessels are coagulated. Other investigators have hypothesized that a specific growth factor or angiogenic factor is responsible for the development of new blood vessels and that laser treatment has its effect by destroying cells that produce this factor. Newer evidence strongly suggests that new blood vessel formation occurs in response to a change in the relative balance among a group of modulating (EMFs) that are secreted by cells within the retina and adjacent tissue. These extracellular modulating factors control

The ultrastructural pathology of congenital murine toxoplasmic retinochoroiditis. Part II: the morphology of the inflammatory changes

A congenital murine model of toxoplasmic retinochoroiditis was employed to study the ultrastructural pathology of retinal parasitization by Toxoplasma gondii. Forty-two eyes from infected mice (18-22-weeks-old) and 24 eyes from control animals were studied by light microscopy (semithin sections). Twenty-six of the eyes from infected animals and six from the control group were subsequently selected for transmission electron microscopy. Control tissues showed no significant abnormality. The pathological changes in diseased tissues ranged in severity from low-grade mononuclear cell infiltration in the subretinal space to complete destruction of the outer retina, the retinal pigment epithelium and the choroid in the presence of a granulomatous inflammatory reaction. Phagocytosis of photoreceptor outer segments by macrophages was observed. Both macrophages and lymphocytes appeared to mediate photoreceptor lysis in eyes which were moderately affected by the disease. Severely affected eyes exhibited vasculitis and inflammatory cell invasion into the vitreous. A lymphoplasmacytoid cell infiltrate was present in the outer retina and choroid in these eyes. There was no evidence that Toxoplasma cysts provided foci for inflammatory cell attack.

Immunohistochemistry and Electron Microscopy of Choroidal Infiltrates and Dalen-Fuchs Nodules in Sympathetic Ophthalmic

An immunohistological study using monoclonal antibodies directed at specific membrane antigens of various inflammatory cells was carried out in order to evaluate the identity and topographic localization of the immunocompetent cells in an enucleated eye from a 6-year-old black patient with a three-month history of sympathetic ophthalmia. Correlative light and transmission electron microscopic examination of serial sections was also performed. The data demonstrated that the predominant cells within the choroidal infiltrate were T-lymphocytes (Leu 1+). T-cell subset analysis disclosed that most of these cells harbored specific antigenic determinants of the helper phenotype (Leu 3a+). A smaller proportion of the T cells demonstrated the specific determinants of the suppressor subtype (Leu 2a+). The helper/suppressor ratio varied slightly and ranged in most areas of the choroid between 3:1 and 4:1. Additionally, approximately 15% of the infiltrating lymphocytes harbored the Leu 14+ determinant specific for B cells. The latter were located in the outer choroid adjacent to the sclera. Very few natural killer (NK) cells (Leu 7+) were identified throughout the choroid. The granulomatous foci in the choroid were composed mainly of epithelioid cells and histiocytes expressing the OKM1+ and M221+ antigenic determinants on their membranes and demonstrating a high cytoplasmic nonspecific esterase activity (ANAE+). Within the Dalen-Fuchs nodules, similar to the choroidal nodules, there was a predominance of histiocytes and epithelioid cells (OKM1+, M221+, ANAE+), a few T-helper cells (Leu 1+, Leu3a+) and some OKM1−, M221− cells whose origin could not be determined. These findings were corroborated by electron microscopic observations of serial sections. Careful light and electron microscopic studies disclosed breaks in Bruch's membrane underlying some of Dalen-Fuchs nodules. In our opinion, these observations may be interpreted as the demonstration that Dalen-Fuchs' nodules and the choroidal granulomatous foci could be formed by identical cells of similar function and origin.

Leber's Congenital Amaurosis

An early stage of Leber's congenital amaurosis, characterized by white spots or lines in the fundus, occurred in two children. Light microscopic examination of eyes obtained from one child, a 16-month-old Japanese girl, revealed subretinal deposits corresponding to the white spots and lines in the fundus deposits. Light and electron microscopic examination of the eye showed distinctive changes in the outer retinal layers and choroid, while the inner retinal layers were nearly normal. Characteristic early lesions of congenital amaurosis appeared to be produced by deposits consisting of loose outer segments and apical processes of the pigmental epithelial cell and macrophages. Undifferentiation in the nuclei of the photoreceptor cell, the inner segment, the pigment epithelial cell, and the choriocapillaris were likely characteristics of the early changes of congenital amaurosis.