Electroretinographic Effects of an Intravitreal Injection of Triamcinolone in Rabbit Retina

Abstract

To investigate the clinical, histologic, and electroretinographic effects of intravitreal injection of triamcinolone acetonide suspension in the rabbit retina. Methods: Three groups of 6 rabbits each received intravitreal injections. Group 1 received 4 mg of triamcinolone acetonide, group 2 received an equal volume (0.1 mL) of the corticosteroid supernatant, and group 3 received 4 mg of triamcinolone acetonide with the supernatant replaced with balanced salt solution. Uninjected left eyes served as controls. Electroretinograms were obtained at baseline and at 3 to 4 and 6 to 7 days after injection of triamcinolone. Enucleated eyes were examined histologically. Results: Ocular examination revealed no differences among the 3 groups. When subjected to stimulation with moderate to high flash intensities, eyes that had received intra-vitreal injections of triamcinolone (groups 1 and 3) had a 10% to 25% increase in dark-adapted a-and b-wave electroretinographic amplitudes. No histologic differences were observed between injected and control eyes. Conclusions: Intravitreal injection of 4 mg of triamcinolone acetonide does not cause a toxic reaction in the rabbit retina after 7 days. Triamcinolone therapy may augment the rod-driven electroretinographic responses, suggesting a mechanism by which visual function may improve. Clinical Relevance: Evaluation of the toxic effects of triamcinolone is useful because of increased applications of intravitreal injection.

Frequency spectrum and amplitude analysis of dark- and light-adapted oscillatory potentials in albino mouse, rat and rabbit

“…3. The ERG waveforms and amplitudes are comparable to previous studies in mouse, rat and rabbit [7,21,22]. Mice have the most evident OP responses among these species, while OPs of rabbits are small.…”

Frequency spectrum and amplitude analysis of dark- and light-adapted oscillatory potentials in albino mouse, rat and rabbit

“…3. The ERG waveforms and amplitudes are comparable to previous studies in mouse, rat and rabbit [7,21,22]. Mice have the most evident OP responses among these species, while OPs of rabbits are small.…”

Long-term Retinal Toxicity of Intravitreal Commercially Available Preserved Triamcinolone Acetonide (Kenalog) in Rabbit Eyes

“…The preponderance of data in the study by Dierks et al 12 and in our study seem to support the conclusion that IVTK injection achieving an intravitreal benzyl alcohol concentration of 0.071% (0.1 mL of 0.99 mg/mL benzyl alcohol in 1.4 mL rabbit vitreous) does not cause diffuse retinal toxicity. Morrison et al 13 recently reported that intravitreous 0.073% benzyl alcohol results in localized areas of photoreceptor loss inferiorly at 2 weeks in the rabbit.…”

“…At 1 of 7 stimulating intensities (i.e., at -0.83 log scot cd ⅐ s/m 2 ), they observed a statistically significant (P ϭ 0.02) increase in b-wave ratio between IVTK eyes and uninjected eyes and between supernatant-injected eyes and uninjected eyes but not between any of the other groups, and they concluded that IVTK may enhance retinal function. 12 We think this enhancement likely represented a chance finding resulting from multiple comparisons, as also occurred during statistical analysis in our study.…”

“…Although a previous study found no toxicity 1 week after IVTK when used at a intravitreal concentration only 2.6 times that used in the clinical setting 12 and another study found long-term toxicity at intravitreal concentrations greater than 5 times that used in clinical practice, 14 the present study sought to examine long-term toxicity at the lower intravitreal concentration of 2.6 times used in the clinical setting. Electroretinography showed no statistically significant difference between IVTK-injected and control eyes in a sat or b max,scot at 2 or 12 weeks after injection.…”

“…Previous studies have reported contradictory results: though some authors claim IVTK enhances retinal function, as demonstrated by electroretinography, 12 others have found no change, and still others have found a profound decline. Dierks et al 12 investigated the electroretinographic and histologic effects of IVTK up to 7 days after injection.…”

Frequency spectrum and amplitude analysis of dark- and light-adapted oscillatory potentials in albino mouse, rat and rabbit

“…3. The ERG waveforms and amplitudes are comparable to previous studies in mouse, rat and rabbit [7,21,22]. Mice have the most evident OP responses among these species, while OPs of rabbits are small.…”

Long-term Retinal Toxicity of Intravitreal Commercially Available Preserved Triamcinolone Acetonide (Kenalog) in Rabbit Eyes

“…The preponderance of data in the study by Dierks et al 12 and in our study seem to support the conclusion that IVTK injection achieving an intravitreal benzyl alcohol concentration of 0.071% (0.1 mL of 0.99 mg/mL benzyl alcohol in 1.4 mL rabbit vitreous) does not cause diffuse retinal toxicity. Morrison et al 13 recently reported that intravitreous 0.073% benzyl alcohol results in localized areas of photoreceptor loss inferiorly at 2 weeks in the rabbit.…”

“…At 1 of 7 stimulating intensities (i.e., at -0.83 log scot cd ⅐ s/m 2 ), they observed a statistically significant (P ϭ 0.02) increase in b-wave ratio between IVTK eyes and uninjected eyes and between supernatant-injected eyes and uninjected eyes but not between any of the other groups, and they concluded that IVTK may enhance retinal function. 12 We think this enhancement likely represented a chance finding resulting from multiple comparisons, as also occurred during statistical analysis in our study.…”

“…Although a previous study found no toxicity 1 week after IVTK when used at a intravitreal concentration only 2.6 times that used in the clinical setting 12 and another study found long-term toxicity at intravitreal concentrations greater than 5 times that used in clinical practice, 14 the present study sought to examine long-term toxicity at the lower intravitreal concentration of 2.6 times used in the clinical setting. Electroretinography showed no statistically significant difference between IVTK-injected and control eyes in a sat or b max,scot at 2 or 12 weeks after injection.…”

“…Previous studies have reported contradictory results: though some authors claim IVTK enhances retinal function, as demonstrated by electroretinography, 12 others have found no change, and still others have found a profound decline. Dierks et al 12 investigated the electroretinographic and histologic effects of IVTK up to 7 days after injection.…”

Frequency spectrum and amplitude analysis of dark- and light-adapted oscillatory potentials in albino mouse, rat and rabbit

“…3. The ERG waveforms and amplitudes are comparable to previous studies in mouse, rat and rabbit [7,21,22]. Mice have the most evident OP responses among these species, while OPs of rabbits are small.…”

Long-term Retinal Toxicity of Intravitreal Commercially Available Preserved Triamcinolone Acetonide (Kenalog) in Rabbit Eyes

“…The preponderance of data in the study by Dierks et al 12 and in our study seem to support the conclusion that IVTK injection achieving an intravitreal benzyl alcohol concentration of 0.071% (0.1 mL of 0.99 mg/mL benzyl alcohol in 1.4 mL rabbit vitreous) does not cause diffuse retinal toxicity. Morrison et al 13 recently reported that intravitreous 0.073% benzyl alcohol results in localized areas of photoreceptor loss inferiorly at 2 weeks in the rabbit.…”

“…At 1 of 7 stimulating intensities (i.e., at -0.83 log scot cd ⅐ s/m 2 ), they observed a statistically significant (P ϭ 0.02) increase in b-wave ratio between IVTK eyes and uninjected eyes and between supernatant-injected eyes and uninjected eyes but not between any of the other groups, and they concluded that IVTK may enhance retinal function. 12 We think this enhancement likely represented a chance finding resulting from multiple comparisons, as also occurred during statistical analysis in our study.…”

“…Although a previous study found no toxicity 1 week after IVTK when used at a intravitreal concentration only 2.6 times that used in the clinical setting 12 and another study found long-term toxicity at intravitreal concentrations greater than 5 times that used in clinical practice, 14 the present study sought to examine long-term toxicity at the lower intravitreal concentration of 2.6 times used in the clinical setting. Electroretinography showed no statistically significant difference between IVTK-injected and control eyes in a sat or b max,scot at 2 or 12 weeks after injection.…”

“…Previous studies have reported contradictory results: though some authors claim IVTK enhances retinal function, as demonstrated by electroretinography, 12 others have found no change, and still others have found a profound decline. Dierks et al 12 investigated the electroretinographic and histologic effects of IVTK up to 7 days after injection.…”