Biomedical subjects

M Stefaniotou

Publications and source records attributed to M Stefaniotou.

11 recordsLinked to original sources

PubMed2006

Angiogenesis in pterygium: study of microvessel density, vascular endothelial growth factor, and thrombospondin-1.

PURPOSE: This retrospective study aims to elucidate the role of angiogenesis in the pathogenesis of pterygium. We evaluated microvessel density (MVD), and expression of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1). METHODS: Fifty-two surgically excised pterygia and seven normal conjunctivae were immunohistochemically studied applying the streptavidin-biotin method in paraffin-embedded tissue sections. Monoclonal antibodies were targeted against CD31, VEGF, and TSP-1 proteins. RESULTS: Pterygium presented with statistically significant higher average count of microvessels compared to normal conjunctivae (17.97+/-8.5 vs5.72+/-5 per high power field, P=0.001). In 24/52 (46.2%) cases of pterygium, high expression levels for VEGF were demonstrated, whereas the mean percentage of VEGF-positive epithelial cells was 58.03%. Furthermore, normal conjunctival presented statistically significant higher expression levels for VEGF in epithelial cells (83.14+/-36.08 vs58.03+/-31.23%, P=0.007). On the contrary, the presence of VEGF immunoreactivity in vascular endothelial and stromal cells was significantly higher in pterygium tissues (P<0.0001). Stromal staining for TSP-1 was detected in only 29/52 (55.8%) of the cases and no correlation with normal conjunctivae was found. Finally, statistically significant positive correlation between MVD values and stromal VEGF expression was found (P=0.049). CONCLUSION: The angiogenesis-related factors that were studied proved to be highly expressed in pterygium tissue. On the contrary, TSP expression level was low, allowing inducers of angiogenesis to act uninhibited. This phenomenon could provide the pathogenic basis of pterygium formation.

Aged↗

PubMed2006

Intravitreal dirofilariasis: a rare ocular infection.

Human ocular dirofilariasis is a zoonotic disease, rare in Europe, caused by filarial nematodes. The parasite is either encysted in a subcutaneous nodule or located under the bulbar conjunctiva. We report the case of a 62-year-old man with intravitreal dirofilariasis, which is a rare site of presentation of the nematode in the human eye. It was located in the fundus area and was surgically removed. The nematode was identified as Dirofilaria repens (D. conjuctiva) by two different Microbiology Departments, making this the fifth report of identified intravitreal dirofilariasis caused by D. repens in the relative literature.

Animals↗

PubMed2005

Immunohistochemical study of angiogenesis and proliferative activity in epiretinal membranes.

Formation of epiretinal membranes (ERMs) is a serious complication of retinal diseases, the most important being proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). In this study, our goal was to (i) calculate the microvessel density (MVD), (ii) evaluate vascular endothelial growth factor (VEGF) expression and (iii) correlate angiogenesis with the proliferative activity as expressed by the expression of Ki67 marker, in both membrane types. We performed immunohistochemistry in 14 PVR and eight PDR membranes, using antibodies against CD34, VEGF, Ki67 and glial fibrillary acidic protein. PDR membranes presented higher average count of microvessels compared with PVR membranes (p = 0.0015). No differences were observed concerning VEGF expression (p = 0.1). The expression of Ki67 was not correlated with microvessel number or VEGF expression. Our study confirms the presence of vascularisation in PDR membranes, as well as the presence of VEGF even in avascular PVR membranes, suggesting that immunoreactivity for VEGF may not be accompanied by angiogenesis.

Cell Proliferation↗

PubMed1998

Ocular surface and environmental changes.

PURPOSE: To investigate if ocular surface and precorneal tear film are influenced by the environment. METHOD: We studied the environmental influences on the ocular surface using the tests Break-up time, Schirmer-1 test and Rose Bengal staining. We correlated the values of the above tests among three groups of normal people from different places in Greece with different climates and levels of atmospheric pollution. Group A consisted of 57 persons coming from an area with a dry and warm climate and heavy atmospheric pollution. Group B consisted of 55 normal persons coming from an area with a dry and warm climate and a low level of atmospheric pollution. Group C consisted of 55 persons coming from an area with a humid and cool climate and a low level of atmospheric pollution. RESULTS: Schirmer-1 test and Break-up time are influenced by the climatic conditions but they are not influenced by the atmospheric pollution, while Rose Bengal staining is not influenced either by the climate or by the atmospheric pollution. CONCLUSION: The precorneal tear film is much more influenced by the climatic conditions than by the atmospheric pollution.

Adolescent↗

PubMed1995

Long-term visual results after laser photocoagulation for diabetic maculopathy.

A study was performed to determine the long-term visual results after laser photocoagulation in diabetic maculopathy. One hundred and four eyes of 56 diabetic patients underwent modified grid laser photocoagulation for diabetic maculopathy according to the protocol of the European Study Group on Diabetic Eye Complications and the Early Treatment Diabetic Retinopathy Study. Follow-up ranged from 12 months to 2.5 years. Eyes with visual acuity less than 0.2 before treatment were included in group A, those with visual aquity of 0.3-0.6 in group B and eyes with visual acuity more than 0.7 were included in group C. At 1 year, 79.4% of the eyes of group A improved or preserved their visual acuity, with 38.9% of group B and 88.2% of group C; at 2 years, 86.6% of group A, 30% of group B and 66.7% of group C and at 2.5 years 85.7% of group A, 27.3% of group B and 75% of group C improved or preserved their visual acuity. The percentages of positive results concerning the visual acuity for groups A and C were significantly greater compared with those for group B. These results suggest that modified grid laser photocoagulation for the management of diabetic maculopathy is an effective procedure in 'early treated' eyes (visual aquity > or = 0.7). It contributes to improve a little or to preserve low vision but it did not affect the natural course of disease in the rest of the eyes.

Aged↗

PubMed1995

Panretinal cryopexy for the management of neovascularization of the iris.

Panretinal cryopexy was used for the treatment of 15 eyes with neovascularization of the anterior segment, treated with panretinal photocoagulation in the past. The eyes were classified preoperatively according to grade of neovascularization of the iris and anterior chamber angle using Weiss' and Gold's device system. Four eyes had rubeosis iridis with normal intraocular pressure and 11 had neovascular glaucoma. Rubeosis was secondary to proliferative diabetic retinopathy and/or central retinal vein occlusion. Nine eyes with grade 0, I and II neovascularization showed regression of neovascularization and controlled intraocular pressure. Six eyes with grade IV showed regression of neovascularization but uncontrolled intraocular pressure. All those eyes presented extensive peripheral anterior synechias.

Aged↗

PubMed1994

Factors influencing the accuracy of the SRK formula in the intraocular less power calculation.

Several intraocular lens (IOL) power calculation formulas (either theoretical or empirical) are used to determine the emmetropic IOL power) The Sanders-Retzlaff-Kraff (SRK) linear regression formula is among the most widely recognized empirical ones. In the present study intraocular lens power calculation aiming at emmetropia was performed, using SRK formula, in 145 cataractous eyes undergoing lens implantation. The final refraction was evaluated at 8 to 12 months after surgery. The purpose of this study was the identification and quantitative evaluation of the factors which influence significantly the accuracy of SRK in the intraocular lens power calculation. The following factors were studied: (1) the error in preoperative biometry with regard to the difference between post and preoperative axial length measurements, (2) the position of the implantation of the intraocular lens (anterior versus posterior chamber), (3) the intraocular lens style, (4) the intraocular lens power level, (5) the preoperative corneal astigmatism, (6) the surgically induced corneal astigmatism, and (7) the postoperative astigmatism. Multiple regression and stepwise regression analysis showed a strong correlation (R2 = 0.65; p < 0.001) between postoperative refractive error (Rf) and error in preoperative biometry (delta AL), surgically induced corneal astigmatism (SIA) and postoperative astigmatism (Ap) only. This correlation is expressed by the following equation: Rf = 0.07 -2.55 delta AL -0.42 SIA + 0.34 Ap. This equation indicates the quantitative effect of each factor on the accuracy of the SRK formula, by defining the pattern of the fluctuations of the amount or state (myopic or hyperopic) of refractive error induced by changes of variables delta AL, SIA and Ap.

Aged↗

PubMed1992

The cornea in exfoliation syndrome.

Exfoliation syndrome (EXS) is a disorder which affects some structures of the eye. We studied the changes of the cornea in patients with EXS and compared with those in normal persons. A prospective study of 96 consecutive patients more than 70 years of age was set up. 48 of them (70 eyes, group A) had exfoliation in one or both eyes and 48 (group B) had no ocular disease other than senile cataract. None of the patients had any systemic disease. The endothelium and thickness of the central cornea were studied. Endothelium of the eyes with EXS showed significantly (p < 0.05) lower cell density than those of group B. Cornea in group A was significantly thicker (p < 0.05) than in group B. The morphology of the endothelium in group A showed a decrease of hexagonal cells and a higher rate of polymegethism compared to group B. Corneal thickness and endothelium showed no significant differences between the eyes with EXS and normal fellow eyes. These results add another risk factor, the fragile cornea, in eyes with EXS, in cataract surgery.

Aged↗

PubMed1990

The frequency of pseudoexfoliation in a region of Greece (Epirus).

A study of pseudoexfoliation syndrome frequency has been evaluated in the northwest of Greece (Epirus). In 700 examined patients (greater than or equal to 50 years old) pseudoexfoliation was found in 170 (24.3%). The frequency of pseudoexfoliation increases with age; no difference was noticed between sexes. Ocular hypertension (greater than 22 mmHg) was found in 39.5% of the patients.

Age Factors↗

PubMedDate not supplied

Vitrectomy results for diffuse diabetic macular edema with and without inner limiting membrane removal.

PURPOSE: To determine whether vitrectomy for diffuse diabetic macular edema with and without internal limiting membrane (ILM) peeling is equally effective in reducing edema. METHODS: The authors retrospectively analyzed the surgical outcomes in 73 eyes of 52 patients with diffuse diabetic macular edema. Eighteen eyes (Group A) underwent three-port pars plana vitrectomy with posterior hyaloid membrane (PHM) removal, while 55 eyes (Group B) had pars plana vitrectomy with additional ILM peeling after PHM removal. RESULTS: Intraoperatively, the posterior hyaloid was found to be attached to the macula in all eyes. In Group A, macular edema resolved completely in 8 eyes (44.4%) with improvement of visual acuity (VA). In Group B, VA improved in 38 eyes (69.1%) with complete resolution of edema. The results of this study indicated that vitrectomy effectively reduced macular edema but eyes with ILM peeling (Group B) presented better results than those without ILM peeling. Another important factor related to the outcome seems to be the level of glycosylated hemoglobin (HbA1c). CONCLUSIONS: In eyes with diffuse diabetic macular edema vitrectomy seems to be effective, but additional ILM peeling presented better results.

Aged↗

PubMedDate not supplied

Immunohistochemical study of extracellular matrix components in epiretinal membranes of vitreoproliferative retinopathy and proliferative diabetic retinopathy.

PURPOSE: The migration, proliferation, differentiation, and adhesion of cells and other cellular functions are influenced by the surrounding extracellular matrix in normal and wound healing conditions. The formation of epiretinal membranes, a wound healing process, is a serious complication of retinal diseases, the most important being proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). In the present study, the authors investigated the expression of various extracellular matrix components and in particular tenascin, fibronectin, laminin, collagen IV, and MMP-3 glycoprotein as well as the expression of glial fibrillary acidic protein in each type of epithelial membrane in order to elucidate the role of these molecules in the formation of these two types of membranes. METHODS: The authors performed immunohistochemistry in 14 PVR and 14 PDR membranes, using antibodies against the above mentioned extracellular matrix components. Tenascin and fibronectin were observed as major components in the extracellular matrix, while laminin and collagen type IV were detected as minor components in both types of membranes. A higher fibronectin expression in PVR compared with PDR membranes was found (p=0.0035). A positive relationship of its expression with the proliferative activity (p=0.15) and collagen type IV expression (p<0.0001) was also observed. RESULTS: Tenascin expression was positively correlated with glial fibrillary acidic protein positive cells in PDR membranes (p=0.04). Collagen type IV localized around vessels was observed with high levels in PDR membranes (p=0.0031). CONCLUSIONS: The results indicated that the extracellular matrix components seem to be involved in PVR and PDR, contributing to tissue remodeling and perhaps by different pathogenetic pathways, which could reflect different stages of development in these two types of membranes.

Antigens↗