To simulate the posterior vitreous detachment (PVD) in the rabbit, 1 IU hyaluronidase and/or 0.2 ml of perfluoropropane gas was intravitreally injected. Ophthalmoscopic, light microscopic examination prepared by cryotechnique, electron microscopic examination, and electroretinogram were done on the 3rd and 28th postoperative days. As a result, the eyes undergone simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas showed membranous structure split from the internal limiting membrane of the superior retina in 3 days after injection. The eyes also demonstrated membranous structure separated from the superior retina after 28 days, simulating vitreous detachment. On the contrary, neither agent alone induced vitreous detachment. No toxic retinal changes associated with simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas were observed. Therefore, with a future support by histologic examination other than cryotechnique and by immunohistochemical analysis, the simultaneous intravitreal injection of perfluoropropane gas and hyaluronidase would be a promising method to induce vitreous detachment in non-vitrectomized eye.
Animals ; Drug Combinations ; Electroretinography ; Eye Diseases/chemically induced/pathology ; Fluorocarbons/*toxicity ; Hyaluronoglucosaminidase/*toxicity ; Injections ; Rabbits ; Retina/drug effects/physiology ; Vitreous Body/*drug effects/pathology

The aim was to investigate the proteolytic activity of plasmin and its long-term complications. Plasmin was injected into the vitreous cavity of rabbits' eyes. Slit lamp biomicroscopy and electroretinography were performed. Rabbits were serially sacrificed at four months, and globes fixated and prepared for light and transmission electron microscopy. In both the plasmin-injected and control eyes, electroretinography showed a transient decrease in the amplitude, but this recovered to the baseline level in a week. Under the light microscope, the plasmin-treated eyes had a smooth retinal surface, implying separation of the vitreous cortex from the retina. In the control eyes, the collagen fibers remained on the retinal surface. By transmission electron microscopy, the plasmin-treated eyes showed a vitreous-free retinal surface, but no vitreoretinal separation was observed in the control eyes. Plasmin induces a cleavage between the vitreous and the internal limiting membrane, with no long-term complications, so may be a useful pharmacologic adjunct to vitrectomy.
Animals ; Electroretinography ; Fibrinolysis/*drug effects ; Fibrinolytic Agents/*pharmacology ; Injections ; Plasmin/*pharmacology ; Rabbits ; Research Support, Non-U.S. Gov't ; Retina/drug effects/physiology ; Vitreous Body/*drug effects ; Vitreous Detachment/*chemically induced/pathology

Intravitreal fibrin clots were produced by intravitreal injection of 0.2 ml of autologous plasma in 62 rabbit eyes. The intravitreal injection of 0.25 micrograms or more of tissue plasminogen activator(tPA) resulted in a total clearing of intravitreal fibrin within one day in all treated eyes. This was significantly faster than in the control eyes, in which complete clearing was not seen until 8 days later. This represents the plateau on the dose-response curve in doses ranging from 0.25 to 200 micrograms. With light microscopy and transmission electron microscopy, retinal toxicity was demonstrated in eyes enucleated seven days after injection of 25 micrograms or more of tPA. This study demonstrates that tPA was effective and safe at 12.5 micrograms or less in clearing intravitreal fibrin in an experimental model. These results suggest that low dosages of tPA, probably of 3 micrograms or less, may be useful in the treatment of severe postvitrectomy fibrin formation seen clinically.
Animals ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Fibrinolysis/*drug effects ; Rabbits ; Retina/drug effects/pathology ; Tissue Plasminogen Activator/*toxicity ; *Vitreous Body

This study was designed to determine the maximal safe drug concentration of intravitreal ciprofloxacin in phakic rabbit eyes. Twenty-two eyes of New Zealand pigmented rabbits received midvitreal ciprofloxacin of 100, 200, 400, 600 or 800 microgram in BSS Plus, or BSS Plus only. Retinal toxicity was dose-dependent as determined with electroretinography, light microscopy, and transmission electron microscopy. At a dose of greater than 400 microgram, disorganization of the outer segments was a main pathological finding in transmission electron microscopy. We evaluated retinal function by measuring the electroretinograms for a graded series of flash intensities and by fitting electroretinogram b-wave amplitudes to the Naka-Rushton equation. At a dose of greater than 600 microgram, Rmax was significantly decreased and log K was significantly increased. N-value tended to decrease. A decrease of b-wave amplitudes caused by retinal toxicity could be detected very sensitively with lower luminance stimuli. Determination of retinal toxicity with lower luminance electroretinography revealed a significant decrease of b-wave amplitudes at a dose of greater than 400 microgram. We concluded that a safe dose of intravitreal ciprofloxacin in phakic rabbit eyes was 200 microgram in phakic eyes.
Animals ; Ciprofloxacin/administration & dosage/*toxicity ; Dose-Response Relationship, Drug ; Electroretinography/drug effects ; Injections ; Lens, Crystalline ; Photic Stimulation ; Rabbits ; Retina/*drug effects/pathology/physiopathology ; Rod Cell Outer Segment/drug effects/pathology ; Vitreous Body

Acetates ; pharmacology ; Animals ; Bicarbonates ; pharmacology ; Drug Combinations ; Endothelium, Corneal ; drug effects ; pathology ; Female ; Glutathione ; pharmacology ; Hydrogen-Ion Concentration ; Minerals ; pharmacology ; Ophthalmic Solutions ; pharmacology ; Rabbits ; Retina ; drug effects ; pathology ; Sodium Chloride ; pharmacology ; Vitreous Body ; drug effects

To determine injection time and effective dose of ciprofloxacin in endophthalmitis and to evaluate the effectiveness of dexamethasone. In rabbits, Pseudomonas aeruginosa (2 x 10(4) CFU/0.1 ml) was inoculated intravitreally. At 6, 12, 18, 24 hours postinoculation, single intravitreal doses of ciprofloxacin (300 microgram/0.15 ml or 100 microgram/0.05 ml) alone or with dexamethasone (400 microgram) were given. Electrophysiological and histologic measures were utilized to rate drug effectiveness. 300 micrograms ciprofloxacin was effective in killing P. aeruginosa at 6 and 12 hours postinoculation, but one hundred ug ciprofloxacin was not effective. 300 ug ciprofloxacin had no significant effect in killing P. alphaeruginosa at 18 hrs and 24 hrs postinoculation. Eyes treated with dexamethasone (400 microgram) and ciprofloxacin (300 microgram) at 6 hours postinoculation did not differ from eyes treated with ciprofloxacin alone. Cultures from eyes treated with dexamethasone and ciprofloxacin at 12 hours postinoculation were positive. Cultures from eyes treated with ciprofloxacin alone were negative. The failure of treatment at 18 hrs and 24 hrs postinoculation may be due to either an increased rate of clearance of drugs from the eyes or a reduced bactericidal effect of ciprofloxacin which could be altered by acidic pH, degree of hypoxia or bacterial counts. Dexamethasone had no beneficial effect in the treatment of P. aeruginosa endophthalmitis in the early phase.
Animals ; Anti-Infective Agents/*administration & dosage ; Anti-Inflammatory Agents/*administration & dosage ; Ciprofloxacin/*administration & dosage ; Dexamethasone/*administration & dosage ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Drug Therapy, Combination ; Electroretinography ; Endophthalmitis/*drug therapy/microbiology/pathology ; Eye Infections, Bacterial/*drug therapy/microbiology/pathology ; Pseudomonas Infections/*drug therapy/microbiology/pathology ; Pseudomonas aeruginosa/drug effects/isolation & purification ; Rabbits ; Time Factors ; Vitreous Body/microbiology

PURPOSE: To assess the effect of intravitreal and posterior subtenon injections of triamcinolone acetonide (TA) on intraocular pressure (IOP). METHODS: we reviewed 42 consecutive eyes after intravitreal TA injection (IVTA) and 43 eyes following posterior subtenon TA injection (PSTA). All cases had a minimum follow-up time of three months. After injection, the value and time of the maximal IOP, the amount of IOP elevation and the needs of the medication were assessed. RESULTS: The IOP increased significantly (p<0.001) from 16.3+/-2.5 mmHg preoperatively to a mean maximum of 21.7+/-5.3 mmHg in the IVTA group, and from 15.3+/-4.5 mmHg to 20.6+/-3.0 mmHg in the PSTA group. An elevation in the IOP of more than 5 mmHg from the baseline IOP was seen in 52.4% of the IVTA group at a mean time of 3.1 weeks postoperatively, and 44.2% of the PSTA group displayed an IOP elevation at 5.9 weeks. CONCLUSIONS: Both developed significant elevations of IOP, but this appeared at a later date in the PSTA group. Careful follow-up after local injection of steroids is necessary.
Vitreous Body ; Uveitis, Posterior/*drug therapy/pathology ; Triamcinolone Acetonide/administration & dosage/*adverse effects ; Time Factors ; Retrospective Studies ; Orbit ; Ocular Hypertension/*chemically induced/physiopathology ; Middle Aged ; Male ; Macular Edema, Cystoid/*drug therapy/pathology ; Intraocular Pressure/*drug effects ; Injections ; Humans ; Glucocorticoids/administration & dosage/*adverse effects ; Follow-Up Studies ; Female ; Aged, 80 and over ; Aged ; Adult

We report a case of serous retinal detachment following combined photodynamic therapy (PDT) and intravitreal bevacizumab injection in subfoveal choroidal neovascularization (CNV).
Administration, Oral ; Angiogenesis Inhibitors/administration & dosage/*adverse effects ; Antibodies, Monoclonal/administration & dosage/*adverse effects ; Choroidal Neovascularization/*drug therapy/pathology ; Diagnosis, Differential ; Female ; Fluorescein Angiography ; Fundus Oculi ; Glucocorticoids/administration & dosage ; Humans ; Injections ; Middle Aged ; Photochemotherapy/*adverse effects ; Retinal Detachment/*chemically induced/diagnosis/drug therapy ; Tomography, Optical Coherence ; Triamcinolone/administration & dosage ; Vascular Endothelial Growth Factor A ; Vitreous Body

PURPOSE: To compare intravitreal triamcinolone acetonide (IVT) versus natural course in refractory diabetic macular edema. METHODS: In a prospective interventional case series, twenty five eyes with refractory DME which had been allocated to the sham group of a previous clinical trial underwent new examination and optical coherence tomography about 9 months after their first enrollment. Twenty eyes that met the inclusion criteria, visual acuity (VA) < 20/50 and central macular thickness (CMT) > 200 micrometer, were treated by 4 mg IVT. Evaluations were repeated at 2 and 4 months post-injection to imitate the similar examination intervals after sham injection. Corrected visual acuity and macular thickness changes following IVT were compared to the corresponding changes after sham injection (the natural course). RESULTS: Visual acuity changes within and between each period were not statistically significant. Visual acuity decreased 0.08 & 0.09 logMAR by 2 months and 0.06 & 0.04 logMAR by 4 months after sham and IVT injections, respectively. The changes of macular thickness after IVT and sham intervention were not meaningful either. However, the difference between thickness changes by 4 months (52+/-50 micrometer increase after sham vs. 262+/-115 micrometer reduction after IVT) was significant (P=0.014). CONCLUSIONS: Concerning macular thickness, IVT has beneficial effect on refractory diabetic macular edema as opposed to observation. However, considering visual acuity, it does not induce significant difference in comparison to the natural course of the disease.
Diabetic Retinopathy/*complications/pathology ; Female ; Follow-Up Studies ; Glucocorticoids/*administration & dosage ; Humans ; Injections ; Macula Lutea/drug effects/*pathology ; Macular Edema/*drug therapy/etiology/pathology ; Male ; Middle Aged ; Prospective Studies ; Time Factors ; Tomography, Optical Coherence ; Treatment Outcome ; Triamcinolone Acetonide/*administration & dosage ; Visual Acuity ; Vitreous Body

PURPOSE: To compare intravitreal triamcinolone acetonide (IVT) versus natural course in refractory diabetic macular edema. METHODS: In a prospective interventional case series, twenty five eyes with refractory DME which had been allocated to the sham group of a previous clinical trial underwent new examination and optical coherence tomography about 9 months after their first enrollment. Twenty eyes that met the inclusion criteria, visual acuity (VA) < 20/50 and central macular thickness (CMT) > 200 micrometer, were treated by 4 mg IVT. Evaluations were repeated at 2 and 4 months post-injection to imitate the similar examination intervals after sham injection. Corrected visual acuity and macular thickness changes following IVT were compared to the corresponding changes after sham injection (the natural course). RESULTS: Visual acuity changes within and between each period were not statistically significant. Visual acuity decreased 0.08 & 0.09 logMAR by 2 months and 0.06 & 0.04 logMAR by 4 months after sham and IVT injections, respectively. The changes of macular thickness after IVT and sham intervention were not meaningful either. However, the difference between thickness changes by 4 months (52+/-50 micrometer increase after sham vs. 262+/-115 micrometer reduction after IVT) was significant (P=0.014). CONCLUSIONS: Concerning macular thickness, IVT has beneficial effect on refractory diabetic macular edema as opposed to observation. However, considering visual acuity, it does not induce significant difference in comparison to the natural course of the disease.
Diabetic Retinopathy/*complications/pathology ; Female ; Follow-Up Studies ; Glucocorticoids/*administration & dosage ; Humans ; Injections ; Macula Lutea/drug effects/*pathology ; Macular Edema/*drug therapy/etiology/pathology ; Male ; Middle Aged ; Prospective Studies ; Time Factors ; Tomography, Optical Coherence ; Treatment Outcome ; Triamcinolone Acetonide/*administration & dosage ; Visual Acuity ; Vitreous Body