title: Retinal toxicity of intravitreal triamcinolone acetonide: a morphological study.
abstract: OBJECTIVE
  To evaluate the morphologic effects of intravitreal triamcinolone acetonide (TA) on rabbit retina.
  
  
  METHODS
  Intravitreal injections of 0.5 mg, 1 mg, 4 mg, 8 mg, and 20 mg of TA (Kenalog-40; Bristol-Myers Squibb, Princeton, NJ) in 0.1 mL were given to pigmented rabbits. For control, 0.1 mL of TA vehicle and saline were injected. Animals were killed on day 14, and retinas were analyzed by light as well as electron microscopy.
  
  
  RESULTS
  No ophthalmoscopic change was found. Eyes injected with 0.5 mg and 1 mg of TA did not have morphologic abnormality. Eyes injected with 4 mg, 8 mg, and 20 mg showed destruction of photoreceptor outer segments and migration of macrophage-like cells in the subretinal space. Eyes injected with 20 mg showed more extensive damage and increased pigment granules in the retinal pigment epithelium cells with large oil droplets in the cytoplasm. Electron microscopy also showed loss of photoreceptor/retinal pigment epithelium interdigitations. Eyes injected with vehicle or saline did not show morphologic changes.
  
  
  CONCLUSIONS
  Single intravitreal injection of 0.5 mg or 1 mg of TA did not produce morphologic retinal changes in pigmented rabbits. However, injections of 4 mg, 8 mg, and 20 mg of TA produced outer retina toxic effects. These findings suggest that long-term retinal toxicity studies should be carried out, using single and repeated injections before this therapy becomes more widely used.
authors.affiliation: Retina Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, 02114, USA.
authors.forename: Seung-Young
authors.initials: SY
authors.lastname: Yu
authors.forename: Francisco Max
authors.initials: FM
authors.lastname: Damico
authors.forename: Francesco
authors.initials: F
authors.lastname: Viola
authors.forename: Donald J
authors.initials: DJ
authors.lastname: D'Amico
authors.forename: Lucy H
authors.initials: LH
authors.lastname: Young
mesh_terms: D000818:Animals; D005938:Glucocorticoids / Q000633:toxicity*; D007267:Injections; D014677:Pharmaceutical Vehicles; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D014222:Triamcinolone Acetonide / Q000633:toxicity*; D014822:Vitreous Body
chemical_list: D005938:Glucocorticoids; D014677:Pharmaceutical Vehicles; D014222:Triamcinolone Acetonide