Comparison of the effects of preserved and unpreserved formulations of timolol on the ocular surface of albino rabbits.

Thirty-six albino rabbits, randomly divided into six groups, were used to study their ocular tolerance to (a) 0.25 and 0.50% Timoptol preserved with 0.01% benzalkonium chloride, (b) 0.25 and 0.50% Timoptol-LP, a gel-forming solution preserved with 0. 012% benzododecinium bromide, and (c) 0.25 and 0.50% Timabak unpreserved in the ABAK eyedrops dispenser. All eyedrops were applied in the right eye for 60 days. A clinical follow-up with slitlamp examination and break-up time evaluation was performed for 2 months. At the end of the experimentation, the animals were sacrificed and their eyes enucleated for histological analyses of the conjunctiva and cornea. There was no significant difference in the clinical examination between each group, except for the break-up time evaluation between Timoptol and Timabak at each concentration which was better with the unpreserved timolol. Histological results showed a significant difference in the corneal stroma edema between preserved and unpreserved timolol. This study confirms that using unpreserved timolol may be beneficial for the long-term treatment of glaucomatous patients as it increases tear film stability and decreases epithelial permeability and stromal aggression of the cornea.

[Role of vitrectomy in the treatment of retinal arterial macroaneurysms]. / Place de la vitrectomie dans le traitement des macroanévrysmes artériels rétiniens.

INTRODUCTION: Retinal arterial macroaneurysms are a rare cause of macular hemorrhage. Their treatment by photocoagulation is difficult and often ineffective. MATERIAL AND METHOD: Five aneurysmal cases complicated by a pre or retromacular hematoma or an intravitreal hemorrhage were treated surgically by vitrectomy with peeling of the vitreous cortex, hematoma drainage, dissection of the fibrinous aneurysmal body, perfluorocarbon fluid tamponade facilitating endophotocoagulation and temporary internal gas tamponade. RESULTS: Anatomical and functional results were satisfactory in this short series. One year after surgery, one case of secondary cataract was reported. DISCUSSION: Arterial abnormalities, located on the superior temporal retinal artery, are often discovered after assessment pre or submacular hemorrhage. Functional prognosis of aneurysmal rupture depends on the course of the retrofoveal hematoma. CONCLUSION: Early access to this surgery and good results in this series argue for rapid surgical treatment in sizeable submacular hemorrhage in order to avoid severe effects of subretinal fibrosis.

[Course of epithelial scars after surgical removal of small-size subfoveal neovessels]. / Evolution des cicatrices épithéliales après ablation chirurgicale des néovaisseaux rétrofovéolaires de petite taille.

PURPOSE: We analyzed outcomes of 18 subfoveal neovascular membrane scars after surgery removal in age related macular degeneration. Surface and aspect of pigment epithelial defects were evaluated on angiographic data. RESULTS: We differentiated glial scars and atrophic scars, the most numerous. Scar surfaces were larger compared to the initial preoperative lesions. Central epithelial pigments in scars disappeared in the three months following surgery. After on year, scar surfaces moderately enlarged. DISCUSSION: Ideal approach for retinotomy as well as clinical aspects have to be well evaluated in subfoveal neovascular surgical removal. The angiographic mask effect of the avascular ring surrounding the neovessel is sometime detectable; the approximative scar surface is by this fact more predictable. CONCLUSION: Iatrogenic damages of surgery and postoperative inflammatory lesions must be considered before when a surgical removal of neovascular membranes is suggested.

Riluzole improves functional recovery after ischemia in the rat retina.

PURPOSE: Retinal ischemia leads to neuronal death. The effects of riluzole, a drug that protects against the deleterious effect of cerebral ischemia by acting on several types of ion channels and blocking glutamatergic neurotransmission, were investigated in a rat model of retinal ischemic injury. METHODS: Retinal ischemia was induced by increasing intraocular pressure above systolic blood pressure for 30 minutes. Electroretinograms were recorded before ischemia and at different periods of reperfusion. Riluzole was injected or topically applied to the eye before or after ischemia and twice daily during the reperfusion period. Retinas were harvested for histopathology (toluidine blue and silver-impregnation stainings, Tdt-dUTP terminal nick-end labeling [TUNEL] method) and immunohistochemistry for cytoskeletal glial fibrillary acid protein and c-jun NH2-terminal kinase (p-JNK). RESULTS: Ischemia for 30 minutes caused a reduction of a- and b-waves of the electroretinogram. Systemic and topical treatments with riluzole significantly enhanced the recovery of the reduced a- and b-waves after defined reperfusion times. Riluzole also prevented or attenuated ischemia-induced retinal cell death (necrosis and apoptosis) and reduced the activation of p-JNK, c-jun phosphorylation, and the increase of cytoskeletal proteins induced by ischemic injury. CONCLUSIONS: Riluzole acted in vivo as a potent neuroprotective agent against pressure-induced ischemia. Therefore, riluzole may be a major drug for use in protection against retinal injury.

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.

Study of lymphocyte dynamics in the ocular circulation: technique of labeling cells.

The purpose of this experiment was to study in vivo the dynamic behavior of the lymphocyte in the retinal circulation. We developed a new technique capable of visualization of lymphocyte motion in the retinal and choroidal vessels using a rat model. Live cells freshly removed on a donor animal were labeled by a simple method using fluorescein isothiocyanate. Labeled cells were injected systemically into another animal. Retinal images were reconstituted on a video screen with a scanning laser ophthalmoscope (SLO) utilizing the argon green laser excitation wavelength (514.5 nm) to detect cell fluorescence. Lymphocytes were clearly seen and followed in the retinal vessels. Some slowed down in the capillary system, or even stopped for a few seconds, or were definitively caught in it. Labeled cells remained visible after circulating several times. A method was developed for in vivo visualization of lymphocytes in the retinal circulation. This method has the potential for application in the study of lymphocyte cell behavior under physiological as well as pathological conditions.