Constantine D. Georgakopoulos

Pseudoexfoliation syndrome prevalence in Greek patients with cataract and its association to glaucoma and coronary artery disease

PurposeTo investigate the prevalence of glaucoma and coronary artery disease (CAD) in patients with cataract and pseudoexfoliation (PEX) syndrome.MethodsCross-sectional study of 2140 consecutive patients with cataract admitted at the University Hospital of Patras, Greece, for cataract surgery. Only patients with senile cataract were included in this study. All patients underwent a complete ophthalmological examination that included slit-lamp evaluation with dilated pupil for PEX material in the anterior segment, intraocular pressure (IOP) measurements, and optic disc cup examination. They also underwent an evaluation for CAD by a cardiologist. CAD was considered present if a patient had a history of myocardial infarction, or ischaemia, or abnormal coronary angiography. The patients were classified into two groups: the PEX and the non-PEX group.ResultsOne thousand and eighty-eight (50.8%) patients were men and 1052 (49.2%) were women. The overall prevalence of PEX syndrome was found to be 27.9% and it was found to increase with progressing age. Bilateral PEX was more frequent than unilateral PEX, with the percentage of bilateral PEX raising with progressing age. A total of 132 patients (22.1%) in the PEX group exhibited glaucoma, while in the non-PEX group only 2.5% suffered glaucoma. PEX was also found to be positively associated with the risk for CAD among subjects 50 years or older. No association between CAD and glaucoma was found.ConclusionsPEX syndrome constitutes a major glaucoma risk factor and a CAD risk factor. Patients with PEX should be informed and examined frequently as the risk is present throughout.

Glutathione and Lipid Peroxide Changes in Pseudoexfoliation Syndrome

Purpose:To investigate the oxidative status of the aqueous humor of patients with pseudoexfoliation (PEX) syndrome. Methods: Aqueous humor samples obtained during cataract surgery of patients with PEX syndrome and normal age-matched control subjects were examined for changes in the levels of glutathione (GSH), glutathione disulfide (GSSG), and TBA reactive species (TBARS), products of lipid peroxidation. GSH, GSSG, and TBARS were determined by specific fluorescent assays. Results: Compared to normal controls, PEX syndrome aqueous humor samples showed a decrease of up to 28% of GSH concentration, and GSSG was increased up to 23%. The ratio of GSH/GSSG was 1.7-fold decreased in PEX syndrome samples. TBARS levels were increased by 100% in the PEX aqueous humor samples as compared to the controls. Conclusions: High levels of GSSG and TBARS indicate high oxidative stress, as well as the decrease in the ratio of GSH/GSSG. Our findings suggest a role for oxidation stress in the pathogenesis and the progression of PEX syndrome.

Matrix metalloproteinases and their inhibitors in exfoliation syndrome

The purpose of this study was to determine the expression of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in the aqueous humour of patients with exfoliation syndrome (XFS). XFS and control samples were analysed for their MMP content by zymography and for their tissue inhibitors by ELISA. In XFS eyes, an increase for up to 60% in almost all MMPs was observed, as compared to the controls. MMP-2 and MMP-9 were found to predominate. TIMP-1 levels in XFS samples were slightly decreased, while TIMP-2 levels were similar to those of the controls. Our findings suggest that MMPs may be crucial in the progression of XFS, by degrading the abnormal fibrillar matrix components in the anterior segment tissues of XFS eyes. However, the increased levels of MMPs seem not to be able to overcome the overproduction and accumulation of the exfoliative material.

Tear analysis of ascorbic acid, uric acid and malondialdehyde with capillary electrophoresis

Tears have a significant role in antioxidant defense in ocular tissues and since their collection is quick and noninvasive, their analysis would facilitate monitoring of pathophysiological changes. However, their low volume and low content of antioxidants makes analysis difficult; methods of high sensitivity are needed. In this paper, we present a method for tear analysis of two antioxidant molecules (ascorbic and uric acid) and of a lipid peroxidation indicator (malondialdehyde) with capillary electrophoresis. Tears were collected with Schirmer strips, extracted with a low-pH phosphate buffer, centrifuged through membrane filters and an antioxidant was added. They were stable at -70 degrees C for 15 days. After pilot experiments, optimum electrophoretic separation was achieved in a 25 mM borate buffer, pH 10.0, containing 100 mM sodium dodecyl sulfate at 25 degrees C and 20 kV. The developed method has good repeatability (<5% RSD), precision (<15% relative error values) and high sensitivity (LLOQ values of 20, 2.3 and 2.5 microM for ascorbate, urate and malondialdehyde, respectively). It was applied to the analysis of tears from healthy individuals and the antioxidant levels are in agreement with those obtained with other techniques. This method might serve as a tool to clarify the role of endogenous antioxidants in the pathophysiology of ocular diseases.

Drug-Induced Macular Edema

Macular edema constitutes a serious pathologic entity of ophthalmology resulting in vision loss with a remarkable impact on the quality of life of patients. It is the final common pathway of various systemic diseases and underlying intraocular conditions, with diabetes mellitus being the most frequent cause. Other causes include venous occlusive disease, intraocular surgery, and inflammatory conditions of the posterior segment of the eye. Macular edema is a recognized side effect of various systemic and local medications and requires special consideration among ophthalmologists and other clinicians. Recently, antidiabetic thiazolidinediones have been implicated in the development of macular edema, and a review of the English literature revealed that other systemically administered drugs like fingolimod, recently approved for relapsing forms of multiple sclerosis, the anticancer agents tamoxifen and the taxanes, as well as niacin and interferons have been reported to cause macular edema. Ophthalmologic pharmaceutical agents, like prostaglandin analogs, epinephrine, timolol, and ophthalmic preparation preservatives have also been reported to cause macular edema as an adverse event. The purpose of this article is to provide a short, balanced overview of the available evidence in this regard. The available data and the possible pathophysiologic mechanisms leading to the development of macular edema are discussed. Possible therapeutic strategies for drug-induced macular edema are also proposed.

Angiographically silent cystoid macular oedema secondary to paclitaxel therapy

Bilateral macular oedema is an uncommon side‐effect of paclitaxel administration in oncological patients. We report the case of a 64‐year‐old man who presented with decreased visual acuity due to bilateral macular oedema after paclitaxel administration for lung cancer. Optical coherence tomography scans of both eyes revealed cystoid macular oedema. Fluorescein angiography demonstrated the unusual finding of the absence of localised retinal capillary leakage. Ketorolac eye drops and acetazolamide tablets were prescribed and one month later the cystoid macular oedema resolved with subsequent improvement in visual acuity. This case illustrates the unusual presentation of cystoid macular oedema induced by paclitaxel.

Changes in HNK-1 epitope and collagen type IX in the aqueous humour of patients with pseudoexfoliation syndrome

Purpose. To investigate alterations in the proteoglycan (PG) and glycosaminoglycan (GAG) content of the aqueous humour in patients with pseudoexfoliation syndrome (PEX). Materials and methods. Aqueous humor samples were obtained during cataract surgery from nineteen patients bearing PEX features and twenty-three age-matched normal controls. Protein and IgG were quantified densitometrically after their electrophoretic separation. Collagen type IX, 3-sulphoglucuronic acid (HNK-1 epitope), biglycan and heparan sulphate proteoglycans were detected in Western and dot blots by using specific monoclonal antibodies (MAbs). The immunochemical analysis was performed in native aqueous humour or after degradation of the glycosaminoglycans with chondroitinases. Results. Degradation of the samples with chondroitinases ABC, AC and B revealed that, in the aqueous humour from PEX eyes, collagen type IX and biglycan had a more dermatan sulphate than did normal eyes. In addition, more HNK-1 epitope was observed in PEX eyes, which after similar enzymatic treatment was found to be located mainly in dermatan sulphate sequences. 3-sulphoglucuronic acid was a constituent of the GAG chains of the collagen type IX. We found that the electrophoretic mobility of the bands of collagen type IX and HNK-1 epitope was exactly the same in the aqueous humour of normal and PEX samples; both migrated as four bands at 120, 113, 92.6 and 56 kDa. The PGs bearing heparan sulphate were found only in normal samples. Other PGs were not detected. Conclusion. Because no significant difference was observed in the concentration of albumin and IgG in PEX and normal samples, the blood-aqueous barrier was probably not significantly compromised in PEX patients with cataract but without open-angle glaucoma. The results support the hypothesis that the pathogenesis of PEX can be linked to disturbed metabolism of GAGs and PGs.

Effect of a fixed brimonidine–timolol combination on intraocular pressure after phacoemulsification

PURPOSE: To evaluate the effect of a fixed combination of brimonidine–timolol on intraocular pressure (IOP) after phacoemulsification cataract surgery. SETTING: Department of Ophthalmology, Patras University Hospital, Patras, Greece. DESIGN: Prospective randomized comparative case series. METHODS: Patients scheduled for phacoemulsification were randomly assigned to 1 of 2 groups. The treatment group received 1 drop of brimonidine–timolol fixed combination immediately after surgery, and the control group received no treatment. The IOP was measured preoperatively and 6, 12, and 24 hours postoperatively. RESULTS: The treatment group comprised 28 eyes and the control group, 30 eyes. The mean IOP increased by 0.14 mm Hg ± 3.88 (SD) (P=.88) in the treatment group and increased by 2.8 ± 5.01 mm Hg (P=.007) in the control group. Twelve hours after surgery, the mean IOP decreased by −0.57 ± 3.82 mm Hg (P=.49) in the treatment group and increased by 2.20 ± 4.56 mm Hg (P=.009) in the control group. Twenty‐four hours after surgery, the mean IOP decreased by −1.57 ± 2.30 mm Hg (P=.012) in the treatment group and increased by 0.86 ± 4.21 mm Hg (P=.175) in the control group. The mean IOP change between the 2 study groups 6, 12, and 24 hours postoperatively was statistically significantly different (P=.015, P=.006, and P=.003; respectively). CONCLUSION: The fixed brimonidine–timolol combination effectively reduced IOP 6, 12, and 24 hours after phacoemulsification cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Levels of specific antibodies towards the major antigenic determinant of slime-producing Staphylococcus epidermidis determined by an enzyme immunoassay and their protective effect in experimental keratitis.

Staphylococcus epidermidis is an important cause of bacterial keratitis. Certain S. epidermidis strains produce an extracellular slime layer rich in an acidic polysaccharide with a molecular size of 20 kDa (20-kDa PS). We have demonstrated that the level of 20-kDa PS-specific antibodies significantly rises after establishment of slime-producing S. epidermidis bacteraemia and, furthermore, that rabbit polyclonal antibodies to 20-kDa PS opsonize cells of slime-producing S. epidermidis to a great degree and promote their clearance by polymorphonuclear cells (Arch. Biochem. Biophys. 342 (1997) 389; J. Pharm. Biomed. Anal. 22 (2000) 1029). The purpose of this study was to examine the protective and therapeutic effects both of active immunization, using 20-kDa PS as antigen, and of passive administration of specific antibodies towards the 20-kDa PS in a rabbit keratitis model. For active immunization, 20 rabbits were subcutaneously immunized with 20-kDa PS, whereas for passive immunization specific polyclonal IgG antibodies against 20-kDa PS were administered to 20 rabbits 1 day before induction of infection. Clinical observations were made weekly for 1 month and levels of 20-kDa PS antibodies in serum and aqueous humor in both immunization groups were determined by an enzyme immunoassay. The levels of specific anti-20-kDa PS IgG in serum and aqueous humor following either active or passive immunization were significantly higher as compared with control groups (P<0.001). Although, actively immunized rabbits showed significantly less corneal damage than control animals, passively immunized ones were significantly better protected as compared with both control and those actively immunized. Obtained results suggest that 20-kDa PS plays crucial role in the pathogenesis of S. epidermidis keratitis and that both types of immunization significantly protect against corneal S. epidermidis pathology and damage.

A UPLC–MS Method for the Determination of Ofloxacin Concentrations in Aqueous Humor

A rapid, simple, and specific method based on ultra performance liquid chromatography (UPLC) with mass spectrometry detection has been developed for quantitative analysis of ofloxacin in human aqueous humor using tobramycin as internal standard (IS). Chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 Shield column (150 × 2.1 mm, 1.7 μm) eluted with 95:5 water: acetonitrile (v/v) containing 0.1% formic acid and a flow rate of 0.3 mL/minute. The total analysis time was three minutes with ofloxacin eluting at 1.67 ± 0.03 minutes. The linearity of the method ranged from 0.1 to 8 μg/mL with r2 = 0.998. The method was validated according to FDA guidelines with respect to linearity, accuracy, precision, specificity, and stability. The limits of detection and quantification were 0.03 and 0.10 μg/mL, respectively. The developed method was successfully applied to the analysis of samples that have been obtained from patients.