Subretinal injection of preservative-free triamcinolone acetonide and supernatant vehicle in rabbits: an electron microscopy study.
BACKGROUND
To evaluate the effect of injections of benzyl alcohol (BA)-free triamcinolone acetonide (TA) solution (MTA-PF) and the supernatant vehicle of TA (STA) containing BA into the subretinal space of rabbit eyes.


METHODS
Sixteen rabbits underwent vitrectomy and subretinal injection of 0.02 ml of either 40 mg/ml MTA-PF, 40 mg/ml STA, or balanced salt solution (BSS). The animals were examined 6, 12, and 24 hours and 14 days after the procedure by fundus examination and fluorescein angiography (FA), as well as histological studies by light and transmission electron microscopy. The histological injury was classified in four stages: (1) stage 1, photoreceptor outer segment injury, (2) stage 2, stage 1 + photoreceptor inner segment injury, (3) stage 3, stage 2 + outer nuclear layer damage, and (4) stage 4, stage 3 + retinal pigment epithelium (RPE) damage.


RESULTS
FA showed no window defects in areas where MTA-PF, STA, or BSS have been injected. Histological examination revealed that subretinal BSS-injection resulted in stage 1 damage during entire follow-up. Subretinal injection of MTA-PF resulted in damage stage 2 at 24 h and 14 days after surgery. However, at the STA position, stage 3 damage was noted 24 h and 14 days postoperatively. No RPE or choroidal damage was observed.


CONCLUSIONS
The histological lesions induced by subretinal STA were more relevant than the damage induced by MTA-PF. The vehicle BA may be involved in these abnormalities. The data indicate that care must be taken when using TA during internal limiting membrane peeling in macular hole surgery, due to the possibility of unintentional subretinal migration and for retinal pharmacotherapy.
Maia
Maurício
M
Vision Institute (IPEPO), Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
Penha
Fernando Marcondes
FM
Farah
Michel Eid
ME
Dib
Eduardo
E
Príncipe
André
A
Lima Filho
Acácio A S
AA
Magalhães
Octaviano
O
Freymüller
Edna
E
Rodrigues
Eduardo B
EB
D000818:Animals; D005260:Female; D005451:Fluorescein Angiography; D005938:Glucocorticoids / Q000008:administration & dosage / Q000633:toxicity*; D007267:Injections; D046529:Microscopy, Electron, Transmission; D014677:Pharmaceutical Vehicles / Q000008:administration & dosage*; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage / Q000633:toxicity*; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000648:ultrastructure*; D014222:Triamcinolone Acetonide / Q000008:administration & dosage / Q000633:toxicity*; D014821:Vitrectomy
D005938:Glucocorticoids; D014677:Pharmaceutical Vehicles; D011310:Preservatives, Pharmaceutical; D014222:Triamcinolone Acetonide