Morphologic and clinical effects of subretinal injection of indocyanine green and infracyanine green in rabbits.

PURPOSE: The aim of this study was to determine the effects of subretinal injection of indocyanine green (ICG), infracyanine (IfCG), and balanced salt solution (BSS) in rabbits. METHODS: Ten (10) animals were subjected to a subretinal injection of 0.05% ICG (279 mOsm), 0.5% IfCG (276 mOsm), and BSS (300 mOsm) used as a control. Animals were examined at 6, 12, and 24 h and 14 days following the surgical procedure by indirect binocular ophthalmoscopy, fluorescein angiography (FA), and light and transmission electron microscopy. RESULTS: The subretinal injection of ICG caused damage to all retinal layers and retinal pigment epithelium (RPE) during the entire follow-up. Subretinal injection of IfCG resulted in abnormalities of the photoreceptor outer segments (POSs) during the entire follow-up; however, abnormalities of the photoreceptor inner segments (PISs) and outer nuclear layer (ONL) were observed only 24 h and 14 days after surgery; no RPE damage was observed. FA showed that window defects were more prominent in the subretinal ICG bleb position than the IfCG-related area. BSS caused only abnormalities of the POS layer and no RPE alterations. CONCLUSIONS: Subretinal injection of 0.05% ICG results in more significant retinal damage than 0.5% IfCG. In this model, iodine-free IfCG demonstrates a safer profile than a tenfold lower concentration of ICG, which contains iodine in its composition.

Effects of subretinal injections of indocyanine green, trypan blue, and glucose in rabbit eyes.

PURPOSE: To evaluate the effects of subretinal injections of indocyanine green (ICG), trypan blue, glucose (GL), and balanced salt solution (BSS) in rabbits. DESIGN: Experimental study. PARTICIPANTS: Twenty Dutch-belted rabbits. METHODS: Ten animals underwent vitrectomy and subretinal injection of 0.02 ml of either 0.05% ICG (279 milliosmoles [mOsm]), 0.15% trypan blue (312 mOsm), 5% GL (280 mOsm), or BSS (300 mOsm), which was tested as a control. Ten additional animals underwent subretinal injection of 0.02 ml of 0.046% ICG (251 mOsm), 0.13% trypan blue (260 mOsm), 4.6% GL (253 mOsm), or BSS (300 mOsm). Animals were examined 6, 12, and 24 hours and 14 days after the procedure by fluorescein angiography and fundus evaluation; histologic studies were performed by light and transmission electron microscopy. MAIN OUTCOME MEASURES: Clinical outcome, fluorescein angiography, and histopathologic results. RESULTS: All subretinal blebs were flat 24 hours after the procedure. Fluorescein angiography showed window defects where ICG and trypan blue had been injected. Subretinal BSS and GL resulted in minimal abnormalities of the photoreceptor outer segments (POS) during follow-up. Hypo-osmolar GL caused edema in all retinal layers; pyknosis of the outer nuclear layer (ONL) was observed 24 hours after injection. Subretinal injection of trypan blue resulted in histologic abnormalities 24 hours and 14 days after surgery. Hypo-osmolar trypan blue caused edema of the POS and the photoreceptor inner segments and pyknosis of the ONL 6 and 12 hours after surgery; the retinal pigment epithelium also was affected 24 hours and 14 days after surgery. Subretinal injection of iso-osmolar and hypo-osmolar ICG caused severe damage of all retinal layers during the entire follow-up. CONCLUSIONS: Subretinal injection of 0.05% ICG results in more substantial retinal damage than that associated with the 0.15% trypan blue subretinal injection. The damage induced by hypo-osmolar solutions was more important than that caused by the iso-osmolar solutions. These findings emphasize that care must be taken regarding the solution osmolarity and that subretinal migration of these substances should be avoided during macular hole surgery.