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T.A. Albini, M.M. Abd–El–Barr, P.E. Carvounis, M.N. Iyer, R.R. Lakhanpal, S.M. Wu, E.R. Holz; Long–Term Retinal Toxicity of Intravitreal Commercially–Available Triamcinolone Acetonide . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4297.
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© ARVO (1962-2015); The Authors (2016-present)
Despite the widespread intravitreal use of commercially–available triamcinolone acetonide (Kenalog–40 [K–40], Bristol Meyers Squibb Company, Princeton, New Jersey) following reports from small case series of efficacy in treating certain macular diseases, there is limited safety data available. Indeed, toxicity to cultured retinal pigment epithelium has been demonstrated, although an animal study showed no retinal electroretinographic or histologic changes in the first week following injection. The objective of our study was to investigate whether injection of K–40 may produce histological or electroretinographic changes in the rabbit retina up to 3 months following injection compared with control.
Ten Dutch–belted rabbits (2–2.5 kg) were injected with 4 mg/0.1 ml of K–40 in one eye. Fellow eyes served as controls and were injected with 0.1 ml balanced salt solution. Simultaneous bilateral dark–adapted electroretinography was performed two weeks and twelve weeks after injection in ten and six rabbits, respectively. A–wave and b–wave amplitudes of K–40–injected and control eyes were compared at 2 and 12 weeks following injection at various intensities of light stimulus (16 intensities at 2 weeks, 13 intensities at 12 weeks) using paired Student’s t–tests. Three months after injection, both eyes of three animals were enucleated, fixed in 10% formaldehyde, embedded in paraffin, sectioned, and stained with hematoxylin–eosin.
There was no statistically significant difference (α<0.05) in a– or b–wave amplitudes between the K–40–injected and control eyes at any illumination intensity at two weeks (n=10) and twelve weeks (n=6) following intravitreal injections. Light microscopy disclosed normal retinal layers, retinal pigment epithelium and choriocapillaris in treatment and control eyes.
The present study showed no demonstrable electroretinographic or histologic changes in K–40 injected eyes up to three months following injection, suggesting no immediate or delayed toxicity of 2.6 mg K–40/ ml of vitreous, more than twice the concentration typically used in humans. This strongly supports the safety of intravitreal injection of commercially–available triamcinolone (K–40) and suggests that there may be no advantage to developing and using non–preserved triamcinolone acetonide preparations.
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