Microangiopathic retinopathy in experimental diabetic monkeys.
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Animals↗
Biomedical subjects
M O Tso
Publications and source records attributed to M O Tso.
Histopathologic study of ocular changes in a syndrome of multiple congenital anomalies.
We examined a 5-month-old boy who had an iris coloboma in the left eye, persistent hyaloid artery, macular hypoplasia, left aberrant nerve palsy, and bilateral blepharoptosis. He had microcephaly and bilateral corticospinal tract dysfunction. Additionally, he had brachycephaly, a high arched palate, hypospadias, a malformed left external ear, and bilateral finger contractures. Computed tomography showed agenesis of the corpus callosum. He died at age 5 months. On histologic examination the left eye showed an iris coloboma, ciliary epithelial differentiation to the retina, undifferentiated neuroepithelium beneath the equatorial retina, persistent hyaloid artery, and optic nerve coloboma and pit. These findings may result from failure of the fetal fissure of the optic cup to close, with redundant folds of neuroepithelium and focal aberrant differentiation. The constellation of developmental defects indicates that an insult occurred during the sixth week of gestation.
Abnormalities, Multiple↗
Angioarchitecture of the human choroid.
The angioarchitecture of the human choroid was studied by corrosion vascular casts and scanning electron microscopy. The relationship of the large choroidal arteries and veins, medium-sized arteries and veins, precapillary arterioles and postcapillary venules, and the choriocapillaris is described. At the posterior pole, a lobular arrangement of the choriocapillaris is seen. At the equatorial area, the capillaries run a more direct course, joining the precapillary arterioles to the capillary venules in a spindle-shaped segment of the choroidal vasculature. At the periphery, the choroidal arterioles and venules take a parallel course, with the choriocapillaris joining the adjacent arterioles and venules at a right angle and appearing in a ladder pattern. The regional variation of the angioarchitecture of the human choroid provides supporting evidence for the unique regional characteristics of choroidal blood flow.
Aged↗
Leiomyoepithelioma of iris pigment epithelium.
A 4-year-old boy had a jet-black, nodular lesion growing in his right iris. Detailed clinical and histopathologic studies of this unusual tumor showed the lesion to be derived from the anterior iris pigment epithelium. The tumor cells appeared to be benign and exhibited characteristics of both pigment epithelium and smooth muscle. We have called this tumor "leiomyoepithelioma of iris pigment epithelium."
Child, Preschool↗
Cultured trabecular-meshwork cells: immunohistochemical and lectin-binding characteristics.
We examined the extracellular matrix formation and lectin-binding properties of cultured trabecular-meshwork cells established from cynomolgus monkey and bovine eyes. Using an avidin-biotin complex method, we found that the extracellular matrix in both the monkey and bovine cultures stained intensely with antibodies to fibronectin, type IV collagen, and laminin. These materials were especially prominent when the cultured monkey trabecular-meshwork cells aggregated in clusters, manifesting their close anatomic relationship to trabecular beams. Cell-surface and intracellular lectin-binding properties were studied using eight biotinylated lectins: concanavalin A (Con A), peanut agglutinin (PNA), Ricinus communis agglutinin (RCA), Dolichos biflorus agglutinin (DBA), soy bean agglutinin (SBA), Phaseolus vulgaris (PHA), wheat germ agglutinin (WGA), and Ulex europaeus agglutinin I (UEA I). Both monkey and bovine trabecular-meshwork cells showed positive cell surface and intracellular binding to Con A, WGA, and PHA. Only moderate cell-surface staining was observed with RCA, and no visible staining occurred with PNA, DBA, SBA, and UEA-1.
Animals↗
Histopathological characteristics of neodymium-YAG laser iridotomy in the human eye.
Light and electron microscopic studies of YAG laser iridotomies were performed in two human iridectomy specimens. Full-thickness defects were created and showed stromal and vascular necrosis. The light and electron microscopic configuration of the lesions was compatible with mechanical disruption from shockwaves. Thermal changes were absent in contrast to iridotomies created by argon laser photocoagulation.
Aged↗
Vitreous fluorophotometry in patients with senile macular degeneration.
Twenty-two phakic eyes of 16 patients with varying stages of senile macular degeneration (SMD) underwent vitreous fluorophotometry. The upper tolerance limit of the penetration ratio in 17 eyes of 17 age-matched controls was 6.33 X 10(-6) min-1. Ten of the 22 eyes with SMD had values exceeding this, indicating abnormal blood-retinal barrier function. When the fluorescence recorded in the vitreous but not related to the local intravitreal dye was evaluated, it was greater in those eyes with more severe forms of the disease. All ten eyes with drusen alone and no SMD had normal fluorophotometry values. Vitreous fluorophotometry may be helpful in the diagnosis and classification of SMD.
Aged↗
Retinal photic injury in normal and scorbutic monkeys.
Mild and severe retinal photic injuries were inflicted on 22 eyes of seven monkeys fed a vitamin C-deficient diet and four monkeys given a vitamin C-enriched diet. The retinal lesions were studied by fundus examination, fluorescein angiography, and light and electron microscopy. While the general cellular response to photic injury in the retina of scorbutic animals was not different qualitatively from that in the normal animals, scurvy appeared to cause more severe tissue damage, an exaggerated repair response, and more advanced retinal degeneration. In the four groups of eyes, representing mild and severe photic injury in normal and scorbutic animals, a continuous spectrum of changes was produced. The least damage occurred from mild photic injury in the normal animals, and the most detrimental insult resulted from severe photic injury in the scorbutic animals. We propose that the basic mechanism by which ascorbate mitigates retinal photic injury depends on its redox properties. Ascorbate functions as an antioxidant in the retina. It scavenges superoxide radicals and hydroxyl radicals, quenches singlet oxygen, and reduces hydrogen peroxide, all of which are formed in retinal photic injury. This hypothesis provides an explanation for the high level of ascorbate in the retina. The pathogenetic mechanisms that correspond to the three distinct phases of pathologic changes observed in retinal photic injury are characterized. In phase 1, single oxygen is generated in a photodynamic reaction that damages the photoreceptor elements and pigment epithelium. In phase 2, macrophages attracted from the systemic circulation invade the subretinal space, and a photo-oxidative reaction generates superoxide radicals, hydrogen peroxide, and hydroxyl radicals. These free radicals attack the photoreceptor cells and pigment epithelium to cause further retinal damage. In phase 3, macrophages remain in the subretinal space for as long as 8 months after injury, causing persistent disruption of the blood-retinal barrier. The photo-oxidative reaction appears to linger, resulting in chronic retinal degeneration. It is hypothesized that in some forms of age-related macular degeneration, patients suffer from repeated mild photic insult throughout their lifetime. Aging has been associated with subclinical scurvy, which leads to even greater susceptibility to photic injury. Although ascorbate moderates many biochemical functions of the body and helps the retina ameliorate photo-oxidative injury, it should be regarded as a nutritional supplement to maintain health when consumed in appropriate amounts and not as a therapeutic agent for the treatment of severe insults.
Animals↗
A clinicopathologic study of dye laser photocoagulation on primate retina.
Chorioretinal lesions produced by dye laser photocoagulation were examined on normal monkey retinas, using angiographic and histopathologic techniques. Retinal burns produced by green (514 nm), yellow (577 nm), orange (600 nm), and red (630 nm) laser lights were placed in the posterior pole between the fovea and the major vascular arcades. When examined histopathologically 24 hours after treatment, greater damage to the inner retina and deep choroid was noted with the red laser light than with the green, yellow and orange laser lights. These differences were not detectable 31 days after treatment. There were no appreciable acute differences among the lesions caused by green, yellow and orange irradiation. Laser light at four wavelengths of the orange spectrum (590, 595, 600, and 605 nm) produced comparable chorioretinal destruction in the juxtafoveal zone when examined 24 hours and 31 days after treatment. Retinal arterioles and venules treated with yellow (577 nm) and orange (600 nm) laser light demonstrated endothelial and pericytic cell damage. Changes in the outer retina, pigment epithelium, and choriocapillaris were also present beneath the photocoagulated vessels.
Animals↗
A clinicopathologic study of hematic cysts of the orbit.
Hematic cyst of the orbit has been described in association with various diseases, but its pathogenetic mechanism remains unclear. We treated two patients (two men, 38 and 35 years old) who had growing cysts suspected of being malignant tumors. Surgical exploration of the orbits disclosed birefringent crystals (hematodin) either in the cyst wall or in the cyst's contents. The crystals imitated foreign bodies in their appearance and in the reactions they induced.
Adult↗
Expression of HLA-DR antigen on retinal pigment epithelial cells in retinitis pigmentosa.
Class II (HLA-DR) antigens are cell surface molecules that play a major role in the initiation and perpetuation of immune responses. Although most cells do not constitutively express class II antigens, selected cells can be stimulated to do so in some immunologically mediated disorders. When retinal pigment epithelial cells were evaluated by either immunoperoxidase or immunofluorescent staining of frozen eye sections from normal individuals, HLA-DR antigens were not detected. In contrast, retinal pigment epithelial cells from two patients with retinitis pigmentosa did express HLA-DR antigens. These findings demonstrated that at some time during the course of retinitis pigmentosa, the retinal pigment epithelial cell is activated to express HLA-DR.
Aged↗
Massive retinal gliosis. A reactive proliferation of Müller cells.
Both Müller cells and astrocytes have been implicated in the dispute over the histogenesis of massive retinal gliosis. We studied three cases of massive retinal gliosis by light and electron microscopy and immunocytochemistry. Spindle fibrillary glial cells were joined by zonulae adherentes resembling those of the external limiting membrane of the retina. Furthermore, these cells produced a continuous basement membrane around an extracellular space filled with fine filaments, which was highly suggestive of vitreous cavity. In the proliferating cells, immunoperoxidase technique disclosed the presence of carbonic anhydrase isoenzyme C, characteristically found only in Müller cells. The glial cells in the preretinal membrane away from the gliotic nodule showed similar characteristics. We concluded that both the nodule of massive retinal gliosis and the associated preretinal glial membrane resulted from the proliferation and migration of Müller cells.
Adult↗
Experimental retinal vascular occlusion. II. A clinico-pathologic correlative study of simultaneous occlusion of central retinal vein and artery.
After experimentally occluding the central retinal vein and artery simultaneously at their point of entry into the optic nerve, acute retinal necrosis occurred, but not hemorrhagic retinopathy. In the retinal vasculature, stagnation of blood flow and thrombosis with subsequent recanalization was noted. The necrosis was extensive in the inner retinal layers but focal in the outer retinal layers. The internal limiting membrane was detached and disrupted in every case. Following the post-edematous stage, numerous micro and macroretinal cysts appeared. The peripheral retina showed much less ischemic changes. A clinico-pathologic correlation was made.
Animals↗
Experimental retinal vascular occlusion. III. An ultrastructural study of simultaneous occlusion of central retinal vein and artery.
The retinal changes following the simultaneous occlusion of retinal vessels were examined at an ultrastructural level. The preservation of endothelial cells that prevented leakage of blood and horseradish peroxidase tracer material in the surrounding retinal tissues explained the lack of hemorrhages observed clinically. Mueller cell death resulted in severe structural disorganization of the retina, with disruption of the inner limiting membrane, involvement of the outer retinal layers, and fleurette formation. The retinal macrocysts were derived from ischemic infarction.
Animals↗
Ocular fluorophotometry in the normal- and diabetic monkey.
Normal- and diabetic rhesus monkeys without retinopathy demonstrable by ophthalmoscopy or fluorescein angiography were examined with ocular fluorophotometry to detect alterations in their blood-ocular barriers. All vitreous fluorophotometry values were corrected for fluorescence attributable to background levels and then normalized to a blood fluorescein level of 10 micrograms ml-1. Reproducibility studies demonstrated an average coefficient of variation of 0.17 for all animals combined. Insulin-dependent monkeys, both pancreatectomized and streptozotocin-treated, demonstrated significantly higher posterior vitreous fluorescence levels than either control animals or monkeys treated with streptozotocin that were not insulin-dependent. These results cannot be attributed to differences in fluorescein binding or to vitreous abnormalities. However, 14 out of 24 (58%) of the insulin-dependent animals exhibited posterior vitreous fluorescence values within two standard deviations of the control mean. No correlation was apparent between the vitreous values and age or duration of treatment. No difference in anterior chamber concentrations was found between groups after correction. Our results indicate that alterations in blood-retinal barrier can occur in insulin-dependent diabetic monkeys before development of retinopathy.
Aging↗
Cone-rod dystrophy. A clinical and histopathologic report.
Clinical, histopathologic, and electron microscopic findings in two postmortem eyes from a 29-year-old black man and the clinical and electrophysiologic findings of his 33-year-old sister, both of whom had bilateral atrophic macular lesions, confirmed the diagnosis of cone-rod dystrophy in these two patients. Light microscopy revealed a loss of photoreceptor cells primarily in the peripheral retina and macula, with relative preservation of both rod and cone cells in the equatorial area. Electron microscopy showed abundant lipofuscin-like granules aggregated in the basal portion of the retinal pigment epithelial cells. In the macular area, many retinal pigment epithelial cells were atrophic. The phagocytic capacity of the retinal pigment epithelium appeared to remain intact. The accumulation of lipofuscin-like granules in the retinal pigment epithelium may be one of the significant pathologic changes of this dystrophy.
Adult↗
Nanophthalmic sclera. Morphologic and tissue culture studies.
We performed morphologic and tissue culture studies on scleral tissues obtained from a nanophthalmic patient. Seen by light and electron microscopy, collagens in these unusually thick scleral tissues were arranged in irregularly interlacing bundles. The size of the collagen fibers was more variable than that observed in the controls. These abnormal fibers appeared twisted and, in some areas, were more closely packed. In tissue culture, scleral cells derived from the nanophthalmic patient synthesized proteins and collagen at a rate similar to that of normal control cells. The level of glycosaminoglycan produced, however, was markedly reduced. The modified glycosaminoglycan metabolism in scleral cells may be related to the abnormal packing of collagen bundles, which may in turn contribute to the thickening of sclera and the formation of nanophthalmos.
Adult↗
Nodular adenomatosis of iris pigment epithelium.
A 62-year-old man manifested multiple nodular growths in his left iris and unilateral glaucoma. Detailed clinical and pathologic studies showed that these lesions were adenomas derived from the spurs of Fuchs, Michel, and Grunert in the iris pigment epithelium. We suggest terming this newly described entity nodular adenomatosis of the iris pigment epithelium and propose a classification of primary neoplastic lesions of the iris.
Adenoma↗