Effects of intravitreal ropivacaine on retinal thickness and integrity in the guinea pig
- PMID: 24672138
- PMCID: PMC3964534
- DOI: 10.1016/j.curtheres.2005.08.005
Effects of intravitreal ropivacaine on retinal thickness and integrity in the guinea pig
Abstract
Background: Retrobulbar anesthesia is widely used for ocular surgery.Ocular complications are possible when retrobulbar anesthesia is accidentally injected intravitreally.
Objective: The aim of this study was to determine the relative retinal toxicitiesof ropivacaine hydrochloride, a local anesthetic, using various concentrations in guinea pigs.
Methods: This randomized, investigator-masked, experimental study wasconducted at the Department of Anesthesiology, Dicle University, Diyarbakir, Turkey. The right eyes of 18 guinea pigs were assigned to 1 of 3 treatment groups: 1%, 0.75%, or 0.5% ropivacaine. The right eye of each animal was injected intravitreally with 0.1 mL of 1%, 0.75%, or 0.5% ropivacaine. The left eye of each animal was injected with a balanced saline solution (control). The guinea pigs were euthanized 7 days after injection, and the retinal structures were examined using light microscopy. The total thickness of each retina was measured using an ocular micrometer.
Results: No histologic abnormalities were observed in the control eyes.Retinal damage of most of the retinal section was seen in the eyes receiving study drug. The eyes injected with 0.5% ropivacaine had a generally intact appearance, with the exception of some atrophy and disorganization. Overall, the eyes injected with 1% ropivacaine had significantly more extensive retinal thinning compared with the eyes injected with 0.75% or 0.5% ropivacaine (both, P < 0.01). In the eyes injected with 0.75% or 1% ropivacaine, disorganization of the structure of the retinal layers and atrophy were noted on histopathology. The mean total thicknesses of the retina were significantly less in all ropivacaine-treated eyes compared with that in the controls (P < 0.001).
Conclusions: In this small experimental study, ropivacaine had concentration-dependent toxic effects on guinea pig retinas.
Keywords: animal; guinea pigs; intravitreal; retina; ropivacaine; toxicity.
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