Maria Stefaniotou

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.

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.

Timing of dislocated nuclear fragment management after cataract surgery

Purpose: To determine the timing of vitrectomy in patients with dislocated nuclear fragments after phacoemulsification and to correlate timing with visual outcomes. Setting: University Eye Clinic of Ioannina, Ioannina, Greece. Methods: This was a retrospective review of the records of 26 patients who had phacoemulsification at the University Eye Clinic of Ioannina over a 5‐year period. The mean age of the 13 men and 13 women was 66.9 years (range 59 to 80 years). All patients had nucleus or nuclear fragment dislocation into the vitreous cavity during phacoemulsification and had vitrectomy and removal of the dislocated nucleus. The postoperative follow‐up ranged from 3 to 9 months. Results: Eight patients (30.8%) had vitrectomy at the time of phacoemulsification (Group A), 8 (30.8%) within 3 weeks (Group B), and 10 (38.5%) after more than 3 weeks (Group C). Patients in Group A did not develop complications, and 87.5% achieved a final visual acuity of 5/10 or better. In Group B, 4 patients (50%) developed moderate intraocular inflammation and 5 patients achieved a final visual acuity of 5/10 or better. Six patients in Group C (60%) had phacoanaphylactic glaucoma and 3 (30.0%), retinal detachment; 70.0% had a final visual acuity of 3/10 or worse. Conclusion: Early vitrectomy (fewer than 3 weeks postoperatively) was associated with better visual results, while late vitrectomy resulted in limited visual acuity in a high percentage of patients and increased the risk for glaucoma and retinal detachment.

Our experience with perfluorohexyloctane (F6H8) as a temporary endotamponade in vitreoretinal surgery

Purpose To evaluate the use of F6H8 as a temporary endotamponade for complicated and special cases of retinal detachment instead of silicone oil. Methods We have used F6H8 with 14 patients since February 1999. Eight suffered from rhegmatogenous retinal detachment (RRD) with multiple tears located inferiorly. Three presented inferior traction retinal detachment (TRD) under silicone oil, two suffered from ocular trauma with inferior TRD, and one had idiopathic macular hole. The substance was introduced into the eye after pars plana vitrectomy and membrane peeling if needed, and we tried to introduce as much as possible. Results With F6H8 the retina was easily reattached in all cases, like with perfluorocarbon liquids. The postoperative view was very good. F6H8 was removed in all cases after 3–8 weeks. Anatomical success was achieved in 12 out of 14 eyes. Two eyes presented severe PVR. F6H8 entered the anterior chamber in 4 cases, but no corneal complications occurred. In one case there was a marked IOP rise due to an anterior block, treated with superior iridotomy. In two cases retinal detachment (RD) occurred in the upper part and was treated with additional surgery, F6H8 removal and silicone oil injection. Conclusions F6H8 seems to be a promising tamponade agent for special cases of RD.

Artisan aphakic intraocular lens implantation in cases of subluxated crystalline lenses due to Marfan syndrome.

PURPOSE To assess implantation of an Artisan aphakic intraocular lens (IOL) in cases with subluxated lenses due to Marfan syndrome. METHODS Retrospective study of a small case series comprised of seven eyes (two children and three adults) with subluxated lenses due to Marfan syndrome that underwent lens extraction and Artisan aphakic IOL implantation. Best spectacle-corrected visual acuity and endothelial cell status were the key elements of follow-up examinations. RESULTS No complications occurred during surgery. Visual acuity was improved by > or = 4 Snellen lines in all seven eyes. These results were maintained at the last follow-up. Endothelial cell status remained constant in all cases at 6-month follow-up. CONCLUSIONS In seven eyes with a subluxated crystalline lens due to Marfan syndrome, implantation of an Artisan aphakic IOL improved visual acuity while preserving anterior chamber status.

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.

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.

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.

Factors influencing the accuracy of the SRK formula in the intraocular lens 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 (ΔAL), surgically induced corneal astigmatism (SIA) and postoperative astigmatism (Ap) only. This correlation is expressed by the following equation: Rf = 0.07 −2.55 ΔAL −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 ΔAL, SIA and Ap.

Ocular dirofilariasis: A case series of 8 patients

Purpose: Dirofilaria repens is an endemic parasite in Mediterranean countries that mostly affects animals. Rarely, however, it can infect humans. This case series presents patients with ocular infections due to D. repens. Materials and Methods: A chart review was performed of patients with ocular dirofilariasis after the year 2000, treated at a tertiary referral centre in Greece. Data were collected on the ocular, microbiological, or/and histopathological aspects and treatment. Results: Eight cases of unilateral ocular dirofilariasis were identified, of which 5 were subconjunctival (1 masquerading as nodular scleritis) and were removed through a conjunctival incision, 2 cases were intravitreal and were removed with vitrectomy, and 1 was intraorbital (adjacent to the roof of the orbit). The latter appeared as an encapsulated mass and subsequent histological examination revealed the presence of the parasite. Of the 8 cases recorded after the year 2000, 7 appeared within the last 6 years (4 cases within the last 3 years). The majority of cases involved residents of the Ionian Islands (7 of 8 cases). Conclusions: D. repens can affect various ocular and periocular tissues. A progressive increase in the incidence of dirofilariasis was observed, which is potentially associated with climate changes in warm and moist areas where this parasite is endemic.