Abstract
Purpose: :
The injection of triamcinolone acetonide (Kenacort®) into the vitreous cavity has become a prevalent technique for the visualization of the vitreous body. However, triamcinolone acetonide is a steroidal formulation, and there are side effects such as increased intraocular pressure and increased susceptibility to infection. We studied the usefulness of carbonic anhydrase inhibitors as new agents for vitreous body visualization by examination of the safety of their intravitreal injections and the changes of intraocular pressure.
Methods: :
Experiment 1: Visibility of the vitreous body was studied by administering brinzolamide and acetazolamide solutions into pig vitreous bodies. Experiment 2: Retinal pigment epithelial cells ARPE–19 were cultured in media with various concentrations of triamcinolone acetonide, brinzolamide, and acetazolamide, and concentrations for 50% cell survival were determined using the WST–1 assay. Experiment 3: 100 µL of one of the aforementioned three drugs or saline solution was injected intravitreally into a rabbit after the aspiration of 100 µL of anterior chamber fluid. Intraocular pressure was measured and an ophthalmoscopy was performed before injection and 6 hours, 1 day, 3 days, and 7 days after injection. An electroretinogram (ERG) was obtained at the above time points under pentobarbital anesthesia. Thereafter, rabbits were sacrificed by overdosing with pentobarbital, and eye enucleation was performed. Then the ocular tissues were observed under a light microscope.
Results: :
Pig vitreous bodies were fully visualized using brinzolamide and acetazolamide. The concentrations for 50% cell survival of ARPE–19 cells were 3 mg/mL and 10 mg/mL of brinzolamide and acetazolamide, respectively. When these drugs at these concentrations were injected intravitreally into rabbits, no changes in latencies of a–waves or b–waves and no changes in amplitudes were indicated by ERG. There were no abnormalities in the ophthalmoscopic findings or ocular tissues in light microscopy images. In addition, a significant decrease in intraocular pressure was observed 6 hours after injection.
Conclusions: :
Carbonic anhydrase inhibitors can be used safely for intravitreal injections under the conditions of this study and are indicated to be effective as new agents for the visualization of the vitreous body. An effect of decreasing intraocular pressure is also expected.
Keywords: vitreoretinal surgery • drug toxicity/drug effects