A Study of Central Islands after Excimer Laser phootorefractive Keratectomy

We analyzed computed corneal topography(EH-270,visioptics, Inc., USA) after excimer laser photorefractive keratectomy(PRK, Omnimed, Summit Technology, Inc., USA) to determine the prevalence f central islands, the factors having an influence on their occurrence, and the corneal ablation patterns. PRK was performed with single zone on 314 consecutive myopias(-1.0D~-11.25D) on which topographic analysis was done at least 3 months after surgery. Corneal ablation patterns were classified as uniform, keyhole, semicircular, and central island. Age, sex, amount of attempted correction, preoperative corneal thickness, and ablation zone(5.0mm vs 6.0mm) were studied whether they can affect on the prevalence of central islands. Topographic results showed a uniform ablation patterns in 213 eyes(67.7%), a keyhole ablation in 54 eyes(17.3%),a semicircular ablation in 18 eyes(5.7%), and a central islands in 29 eyes(9.3%). There was no association between prevalence of centralisland and age, sex, amount of attempted correction, or preoperative corneal thickness(P>0.05). Only one of 81 eye(1.0%) with smaller ablation diameter(5.0mm) presented central islands showing the highly statistical significance(P<0.005) while 28 of the 233 eyes(12%) with larger ablation diameter(6.0mm) presented central islands. In conclusion, we think that the ablation diameter is a risk factor in the prevalence of central island, and the further studies for the etiology of central island, which are based on the optical zone should be needed.

Immunohistochemical Study of Periretinal Memberanes in Proliferative Vistreoretinopathy

We Performed an immunohistochemical study to identify the cellular components and involvement of immune mechanism in proliferative vitreoretinopathy, which is a major cause of delayed filure of retinla surgery. The 17 specimens of periretinal membranes -including vitreal membranes- were surgically obtained during the pars plana vitrectomy. The clinical diagnoses were idiopathic or traumatic retinal detachment (9 eyes), proliferative diabetic retinopathy (6 eyes), and pars plannitis (2 eyes). The labeled streptavidin-biotin immunoperoxidase method was used for immunohistochemical stain. The following antigens were detected in periretinal membranes : cytokeratin in 8 (of 17 cases studied for this antigen), glial fibrillary acidic protein (GFAP) in 9 (of 17), vimentin in 15 (of 17), HLA-DR in 14 (of 17). The macrophages and T lymphocyte expressing CD4 or CD8 markers, were not found in any of the membranes. These results suggest that cellular components of periretinal membranes are consists of retinal pigment epithelial cells, glial cells, and fibroblast. The identification of macrophage and T lymphocytes all met with failure. Also, strong positivity of HLA-DR antigen may indicate involvement of the immune mechanism during the course of proliferative vitreoretinopathy.

Condition Dependancy of The Morphologic Changes and The Expressivity of Cytokeratin Subcloneg, Vimentin, and GFAP in Cultured Retinal Pigment Epithelial Cells

To describe and evaluate the morphologic changes and the different expression of cell-specific or correlating protein molecules during cell growth, immunocytochemistry and morphologic observations were done on retinal pigment epithelial(RPE) cells obtained from several culture conditions. These include culture time, spatial or cell density, transdifferentiation, and presence of growth factors. The human fetal and porcine RPE cells were cultured with and without individual growth factor or in combinations inchlding extracellular matrix (ECM), Insulin, basic fibroblatio growth factor (bFGF) and epidermal growth factor (EGF). Mouse monoclonal anti-human, or anti-mouse antibodieg with or without species cross reactlvity against the intermediate filament proteins (cytokeratin, vimentin, GFAP) were used. To determine RPE-specific molecules of cytokeratin, nine commercially available antibodies, representing subclones of Moll's catalog number 1, 5, 7, 8, 10, 14, 17, 18, 19 were applied. The morphological changes and the proliferation of cells started after their attachment on the culture plate as soon as they lost pigment granules. The epithelial cells like fibroblasts occurred in the area where the cellular density was low, and finally, their shape was restored to their original phenotype when the cellular connuency was achieved. The degree of proliferation and the duration of achieving confluency of cells were dependent on whether ECM and growth factors were added in media or not. Cells with the epithelial morphology were positively stained with anticytokeratine antibodies, especially with clone 19, 18, 17, 8 and 7 in human RPE cells; with 19, CAM 5.26 (8/18) in porcine cells. The fusiform or digitating cells of sparse density also expressed vimentin strongly through out all stages, whereas GFAP was not expressed at any stage in either species.

Condition Dependancy of The Morphologic Changes and The Expressivity of Cytokeratin Subcloneg, Vimentin, and GFAP in Cultured Retinal Pigment Epithelial Cells

To describe and evaluate the morphologic changes and the different expression of cell-specific or correlating protein molecules during cell growth, immunocytochemistry and morphologic observations were done on retinal pigment epithelial(RPE) cells obtained from several culture conditions. These include culture time, spatial or cell density, transdifferentiation, and presence of growth factors. The human fetal and porcine RPE cells were cultured with and without individual growth factor or in combinations inchlding extracellular matrix (ECM), Insulin, basic fibroblatio growth factor (bFGF) and epidermal growth factor (EGF). Mouse monoclonal anti-human, or anti-mouse antibodieg with or without species cross reactlvity against the intermediate filament proteins (cytokeratin, vimentin, GFAP) were used. To determine RPE-specific molecules of cytokeratin, nine commercially available antibodies, representing subclones of Moll's catalog number 1, 5, 7, 8, 10, 14, 17, 18, 19 were applied. The morphological changes and the proliferation of cells started after their attachment on the culture plate as soon as they lost pigment granules. The epithelial cells like fibroblasts occurred in the area where the cellular density was low, and finally, their shape was restored to their original phenotype when the cellular connuency was achieved. The degree of proliferation and the duration of achieving confluency of cells were dependent on whether ECM and growth factors were added in media or not. Cells with the epithelial morphology were positively stained with anticytokeratine antibodies, especially with clone 19, 18, 17, 8 and 7 in human RPE cells; with 19, CAM 5.26 (8/18) in porcine cells. The fusiform or digitating cells of sparse density also expressed vimentin strongly through out all stages, whereas GFAP was not expressed at any stage in either species.