Marie Goldschild

Ocular surface inflammatory changes induced by topical antiglaucoma drugs: human and animal studies.

OBJECTIVES To investigate conjunctival and trabecular specimens from patients with glaucoma according to the duration and number of drugs received before filtration surgery, and to confirm, in a complementary experimental model, the role of preservative by comparing the effects of preserved and nonpreserved timolol. STUDY DESIGN Experimental animal and human tissue study. PARTICIPANTS Paired specimens of conjunctiva and trabeculum were taken from 61 patients undergoing trabeculectomy. Twenty-six patients were treated with 2 or more drugs for at least 1 year; 30 had received a beta-blocker for more than 1 year and 5 underwent primary surgery. A second study was performed in 25 rats receiving topical solutions in both eyes for 1 month. INTERVENTION Immunohistochemistry was performed in all biopsy specimens using 12 different monoclonal antibodies. Ocular structures from rats treated for 1 month with preserved 0.5% timolol, nonpreserved 0.5% timolol, or 0.01% benzalkonium chloride were similarly investigated in an experimental study. MAIN OUTCOME MEASURES Inflammatory cell infiltrates and fibroblasts were evaluated in biopsies, as well as in animal specimens, together with histologic changes induced by the drugs applied. RESULTS Twenty-four of 26 conjunctivae and 21 of 24 trabecular pieces from multitreated patients were found to be abnormally infiltrated by cells expressing inflammatory or fibroblastic markers or both. Nineteen of 30 conjunctivae and 9 of 22 trabeculums in the monotherapy group and only 1 of 5 specimens from the primary surgery group were abnormal. In rats, preserved timolol and benzalkonium similarly showed infiltrates together with toxic histopathologic changes as compared to the nonpreserved timolol and control groups. CONCLUSIONS These two combined studies confirmed histopathologic effects of antiglaucomatous drugs on the conjunctiva and showed similar effects in the trabecular meshwork. The experimental study showed that benzalkonium chloride is at least, to a large part, responsible for these toxic or immunoinflammatory effects or both on the ocular structures.

Histopathological effects of topical ophthalmic preservatives on rat corneoconjunctival surface

PURPOSE Long term use of topical drugs has clearly been shown to induce toxic immunopathological changes in the ocular surface. However, little is known concerning the respective roles of active compounds and preservatives. Benzalkonium chloride (BAC) is the most used preservative and its cytotoxicity is well known, but other preservatives have not yet been clearly evaluated. We thus performed a comparative study to investigate toxic side effects induced in the rat ocular surface by applications of various preservatives, with special attention to inflammatory infiltrates. METHODS A total of 35 brown Norway rats were divided into seven groups of five each. They received, for one month, in both eyes, either 0.01% cetrimonium chloride, 0.01% benzalkonium chloride, 0.01% benzododecinium bromide, 0.004% thiomersal, 0.05% methyl parahydroxybenzoate or phosphate-buffered saline (PBS), the last group remaining untreated. Then, animals were sacrificed and eyes were processed for histological and immunological procedures with monoclonal antibodies to rat immunocompetent cells. RESULTS When compared to controls, all preservative-treated eyes consistently showed corneal and conjunctival damage, including epithelial alterations, various degrees of keratinization and inflammatory infiltrates at the limbus and within the conjunctival stroma and epithelium. No difference was found between the five tested drugs. CONCLUSIONS This study confirms that most preservatives used in ophthalmic eyedrops may similarly induce strong histopathological and inflammatory changes in the ocular surface after short term use. Although obtained in animal model, these results confirm strong toxic side effects in patients with preexisting ocular surface disorders and/or receiving topical drugs for long periods.

Correlation between tear IgE levels and HLA-DR expression by conjunctival cells in allergic and nonallergic chronic conjunctivitis

Abstract Background: Chronic conjunctival inflammatory diseases may depend upon various mechanisms. Discriminating allergy from nonspecific inflammation has become of striking importance for diagnosis and treatment. We investigated conjunctival inflammatory response by comparing two objective biological tools, tear IgE and HLA-DR expression by conjunctival epithelium, as indirect indicators of activation of the Th2 and Th1 subsets, respectiv-ely. Methods: Eighty-two patients with chronic conjunctivitis underwent tear IgE measurement by an ELISA technique and quantitation of HLA-DR expression in impression cytology specimens. Forty-two had direct or indirect clinical indications of allergic mechanisms, 26 had chronic conjunctivitis without any sign of allergy, and 14 suffered from isolated nonallergic dry eyes. Results: Patients clinically considered as allergic only showed positive IgE in 47 of 84 eyes (56%), whereas 21% and 25% of eyes with nonspecific conjunctivitis and dry eyes respectively were also positive. IgE levels were significantly higher in the allergic group than in the other two groups. HLA-DR positivity in epithelial cells was found in 28.5%, 48% and 50% of eyes, respectively. HLA-DR expression by epithelial cells was negatively correlated with tear IgE, as most specimens positive to one criterion were negative to the other one (49 eyes DR+, IgE–; 47 eyes DR–, IgE+; only 9 eyes positive to both criteria; chi-square: P=0.0001). Conclusion: As IgE synthesis and HLA-DR induction may represent indirect indicators of the activation of the Th2 and Th1 subsets, association of these two simple tests could be interesting for the routine assessment of the mechanisms of inflammatory ocular surface diseases.

Effects of EGb761 and superoxide dismutase in an experimental model of retinopathy generated by intravitreal production of superoxide anion radical

Abstract · Background: A study was carried out to investigate the effect of two antioxidants –Ginkgo biloba extract (EGb761) and superoxide dismutase (SOD) – in an experimental model of vitreoretinopathy obtained by direct production of oxygen free radicals in the vitreous cavity. · Methods: Twenty-eight pigmented rabbits were used. Vitreoretinopathy was induced by intravitreal injection of 50 µl of a mixture composed of 40 nmol of xanthine and 0.001 IU of xanthine oxidase. Rabbits were randomly distributed into four groups: Group 1 (n=8) did not receive any treatment and served as a positive control. Groups 2 (n=8) and 3 (n=8) received for 1 month EGb761 given orally at a dose of 100 mg/kg/day, respectively 1 day after and 1 week before induction of retinopathy. Group 4 (n=4) was treated by three intramuscular injections of 15 000 IU/kg of SOD, 24 h before induction and 24 and 48 h thereafter. Clinical evaluations and electroretinograms (ERG) were repeatedly performed until the animals were killed at day 28. Histological examinations and immunohistological procedures were performed to ascertain the origin and characteristics of the cellular proliferation and to compare vitreoretinal structures in the four groups. · Results: Intravitreal injection of xanthine–xanthine oxidase produced a strong inflammatory response with vitreous infiltrates and epiretinal membrane formation, inconstantly associated with retinal detachment. ERG showed a decrease of the a-, b- and c-waves beginning within a few hours after injection. Histologic evaluation found an intravitreal and epiretinal infiltration by leukocytes and epithelial-derived cells, dense vitreoretinal membranes and retinal detachments with occasional neovascularization. In the treated groups (groups 2–4), all clinical, electric and histologic data were significantly improved compared to the control group. However, no difference could be found among the three treated groups. · Conclusion: This study demonstrates the strong pathologic effects of free radical production on the retina and the close relationships between free radicals, inflammatory pathways and vitreoretinal proliferative disorders. It also confirms the pharmacological interest of prevention by antioxidants and free radical scavengers.