Superficial Retina Research Articles

Bilateral foveal cysts secondary to Streptococcus constellatus endocarditis

Infective endocarditis can be acute or subacute, depending on the virulence of the causative organism. It can also cause loss of vision by a variety of mechanisms, ranging from embolic retinal artery occlusion to endogenous endophthalmitis. We illustrate the first report of foveal cyst formation secondary to infective endocarditis. A 53-year-old man presented to his general practitioner with a variety of constitutional symptoms, but initial laboratory and imaging investigations revealed only mild normocytic anaemia, and he was discharged from further medical care. Four weeks later he developed bilateral visual loss associated with whitish lesions of the superficial retina at both foveae. These later developed into foveal cysts with disruption of the photoreceptor inner segment-outer segment junction and persistent poor visual acuity of 6/60 OU. No retinal haemorrhages or Roth spots were noted. Only after he presented with visual loss did further investigations reveal the underlying diagnosis of streptococcal endocarditis. Ophthalmologists assessing retinal pathology which presents in association with undiagnosed constitutional symptoms are advised to refer such patients promptly for thorough medical investigation, including blood culture and echocardiography where appropriate.

Ischemic maculopathy in patients with acquired immunodeficiency syndrome

PURPOSE: To describe the characteristics of ischemic maculopathy in patients with human immunodeficiency virus (HIV) infection, as a means of understanding this uncommon disorder more fully. METHODS: This is a multicenter, retrospective review of clinical data available for five HIV-infected patients who were given the diagnosis of ischemic maculopathy. RESULTS: All cases had been diagnosed on the basis of fluorescein angiograms obtained after patients complained of vision loss. Four of the five patients had bilateral macular disease. Visual acuity at presentation in the nine affected eyes ranged from 20/20 to count fingers. Vision loss was gradual in both eyes of one patient and was abrupt in onset in seven eyes. Each of the seven eyes with abrupt vision loss had opacification of the superficial retina and/or intraretinal hemorrhages near the fovea. Fluorescein angiography revealed enlargement of the foveal avascular zone and mild staining of the juxtafoveal vessels in affected eyes. Six eyes had active or clinically inactive cytomegalovirus retinitis at presentation, and a seventh eye developed cytomegalovirus retinitis 2 weeks later. All patients were receiving anticytomegalovirus drugs when they developed visual symptoms. Visual acuity remained stable in five eyes, became worse in two eyes, and improved in two eyes; final visual acuity ranged from 20/25 to count fingers. CONCLUSIONS: Ischemic maculopathy may cause profound and permanent vision loss in HIV-infected individuals. Fluorescein angiography should be considered in all HIV-infected patients with unexplained loss of vision. The pathogenesis of ischemic maculopathy remains unknown.

Experimental models of growth factor-mediated angiogenesis and blood–retinal barrier breakdown

Following chronic ischemia, vascular endothelial growth factor (VEGF) is induced primarily in the ganglion cell layer of the retina. This often results in neovascularization (NV) that originates from the vascular bed closest to the ganglion cell layer. To study the effects of VEGF, independent lines of transgenic mice that express VEGF in the lens and in the retina have been generated. Expression in the lens results in excessive proliferation and accumulation of angioblasts and endothelial cells in proximity to the lens. However, VEGF expression is not sufficient to direct blood vessel organization or maturation in the prenatal mouse. Abnormal vessels do form on the retinal surface, but not until the second postnatal week. In transgenic mice expressing VEGF in the photoreceptors, NV originates from the deep capillary bed—the vascular bed closest to the photoreceptors. NV is accompanied by localized blood–retinal barrier breakdown. NV is also induced in PDGF-B transgenic mice. PDGF-B expression in the lens occurs prenatally and, during this time, mainly affects the perilenticular vessels. Postnatally, transgenic mice expressing PDGF-B in the lens or photoreceptors show a similar phenotype. In both models, a highly vascularized cell mass containing endothelial cells, pericytes, and glia forms in the superficial retina, and the formation of the deep capillary bed is inhibited. The phenotype suggests that an additional factor is necessary for the maturation and penetration of vascular endothelial cells into the retina to form the deep capillary bed.

Purtscher-like retinopathy associated with pancreatic adenocarcinoma

PURPOSE: To investigate a case of Purtscher-like retinopathy that occurred in association with pancreatic adenocarcinoma. METHOD: Case report. RESULTS: A 63-year-old woman presented with multiple gray patches in the central vision of both eyes. Visual acuity was 20/20 in both eyes. Funduscopy showed large peripapillary yellow-white patches within the superficial retina and small superficial retinal hemorrhages in both eyes. The patient subsequently had abdominal pain. Computed tomography of the abdomen demonstrated a large pancreatic mass with extension into the liver. Histologic examination of a percutaneous needle biopsy specimen showed mucinous pancreatic adenocarcinoma. CONCLUSION: Pancreatic adenocarcinoma should be added to the list of systemic diseases that can be associated with Purtscher-like retinopathy.

Development of microglial topography in human retina.

The development of microglial topography in wholemounts of human retina has been examined in the age range 10-25 weeks gestation (WG) using histochemistry and immunohistochemistry for CD45 and major histocompatibility complex class II antigens. Microglia were present in three planes corresponding to the developing nerve fibre layer/ganglion cell layer, the inner plexiform layer and the outer plexiform layer. Distribution patterns of cells through the retinal thickness and across the retinal surface area varied with gestational age. Microglia were elongated in superficial retina, large and ramified in the middle plane, and small, rounded and less ramified in deep retina. Intensely labeled, rounded profiles seen at the pars caeca of the ciliary processes, the retinal margin and at the optic disc may represent precursors of some retinal microglia. At 10 WG, the highest densities of microglia were present in middle and deep retina in the far periphery and at the retinal margin, with few superficial microglia evident centrally at the optic disc. At 14 WG, high densities of microglia were apparent superficially at the optic disc; microglia of middle and deep retina were distributed at more central locations although continuing to concentrate in the retinal periphery. Microglia appear to migrate into the developing human retina from two mains sources, the retinal margin and the optic disc, most likely originating from the blood vessels of the ciliary body and iris, and the retinal vasculature, respectively. The data suggest that the development of microglial topography occurs in two phases, an early phase occurring prior to vascularization, and a late phase associated with the development of the retinal vasculature.

Absence of infectious retinitis after injection of human cytomegalovirus into rabbit eyes.

The rabbit model of human cytomegalovirus (HCMV) retinitis was evaluated by preretinal and intravitreal injection of HCMV into rabbit eyes. Ocular disease was evaluated by indirect ophthalmoscopy, histopathology, and immunohistochemistry. Vitritis, optic nerve congestion, multiple small white infiltrates in the cortical vitreous or on the retinal surface, and retinal detachments were seen. Histopathologic examination showed inflammatory cell infiltration in the preretinal vitreous, optic nerve, and transiently in the superficial inner retina. Retinal structure was preserved except for changes in areas of retinal detachment. No necrosis or destruction of the retina was seen. Immunohistochemistry showed no evidence of cytomegalovirus infection. Inoculation of culture medium containing fetal calf serum caused a similar reaction. It is concluded that vitreous and retinal inoculation of HCMV in the rabbit eye caused nonspecific inflammation without evidence of infection, so this is not a suitable model for HCMV retinitis.

Ophthalmic Manifestations of Tuberous Sclerosis

The ophthalmic manifestations of tuberous sclerosis include a variety of nonretinal ophthalmic findings which, other than adenoma sebaceum of the lids, are uncommon. Approximately half the patients with tuberous sclerosis have retinal or optic nerve hamartomas; in half of these patients the hamartomas occur bilaterally. Three basic morphologic types of retinal hamartomas are recognized: the most common type is a subtle, relatively flat, smooth-surfaced, salmon-colored, semitransparent, and circular or oval-shaped lesion located in the superficial retina, most commonly near or at the posterior pole. The second type is an easily recognized opaque, white, elevated, multinodular calcified lesion that is frequently described as resembling a mulberry. A third type of lesion contains features of the other two, being calcified and nodular centrally, whereas its perimeter is semitranslucent, smooth, and salmon-colored. The hamartomas may be richly vascularized. They generally do not grow, but over decades some of the lesions may become calcified. Visual loss from retinal and optic nerve hamartomas rarely occurs. Because growth and change of the fundus lesions are rare, treatment is not indicated. Retinoblastoma of the optic nerve and retina is the most important lesion that must be differentiated from the hamartomas seen with tuberous sclerosis.

Macrophage products IL-1α, TNFα and bFGF may mediate multiple cytopathic effects in the developing eyes of GM-CSF transgenic mice

GM-CSF transgenic mice develop eye disease during ontogeny that is mediated by autostimulated macrophages. The ocular pathology is characterized in part by corneal and vitreous neovascularization, pronounced GFAP expression by retinal Müller cells and degeneration of the retinal photoreceptor layer. The invading intraocular macrophages express the genes for the cytokines interleukin-1α, tumor necrosis factor α and basic fibroblast growth factor, which may contribute to the multifaceted developmental ocular disorder. These cytokines, suspected to be angiogenic, may be responsible for neovascularization of the cornea in our transgenic animals. GFAP is normally made by astrocytes in the superficial retina and is induced in Müller cells in models of retinal degeneration. This protein is abnormally and copiously produced by Müller cells in the transgenic mice, which we suggest may be due to the release of cytokines from the invading macrophages. We suggest a mechanism by which autostimulated macrophages, through a perturbation of their normal developmental role, may be responsible for photoreceptor cell death in these transgenic animals.

Epivascular glia and paravascular holes in normal human retina

We examined the retinal surface of 28 autopsy eyes by scanning electron microscopy (SEM). Glialike cells or their processes, arranged in rows, were observed along retinal vessels in 22 eyes. Additionally, there were clusters of glialike cells over retinal vessels in 8 eyes. These proliferations ranged from focal to extensive ones, the latter resulting in distinct preretinal membranes. Focal defects of the superficial retina along the vessel were noted in 6 of 28 eyes. Transmission electron microscopic study in 2 surgically enucleated eyes with normal retinae revealed epivascular retinal degeneration and thinning of Müller cells. Glial processes appeared to be covering the defect of the internal limiting membrane and some projections of these cells continued inwards. These findings were consistent with the SEM findings of epivascular glialike structure. Our conclusions are that epivascular glialike structures and paravascular surface defects appear as a common finding in normal senile eyes, and that occasionally membranous formations arise from the epivascular area.

Metastatic Tumor to the Retina and Vitreous Cavity from Primary Melanoma of the Skin: Treatment with Systemic and Subconjunctival Chemotherapy

The cases of two young women with metastatic tumors to the retinas and vitreous cavities from primary melanoma of the skin are discussed. Each presented with 20/20 central visual acuity in both eyes and complaints of floaters related to singularly unusual golden brown cellular aggregates infiltrating the vitreous cavities. Some cells appeared to be emanating from the region of the optic nerves whereas others appeared to originate from the superficial retina, presumably from the retinal vessels. The cellular aggregates were comprised of malignant melanoma cells as determined by histocytology of a vitrectomy specimen in one case and an aqueous aspirate in the other. The clinical appearance of cellular aggregates in the form of regular spherules should alert the clinician to the possibility of malignant rather than inflammatory cellular infiltration. The combined administration of repeated systemic and subconjunctival DTIC in case 1 and BCNU in case 2 was unsuccessful in promoting tumor regression. Histology of one eye, removed because of uncontrolled neovascular glaucoma, revealed numerous melanoma cells in the superficial retina and adjacent vitreous

Vitreoretinal juncture--simple epiretinal membranes.

Simple epiretinal membranes are delicate cellular membranes occurring at the vitreoretinal juncture. They produce no symptoms or macroscopically detectable change, but are a common microscopic finding in enucleated eyes. The ultrastructural features of these membranes were studies in eight eyes surgically enucleated for unrelated ocular conditions or for orbital lesions. Simple epiretinal membranes are composed exclusively of glial cells. Evidence is presented that these cells derive from accessory glia of the superficial retina which react to a variety of stimuli and migrate through breaks in the retinal surface (which may later heal). This pathogenic sequence is discussed in light of present knowledge of retinal accessory glia and their role in retinal disease.