Novel dyes
Michel Eid Farah, F. Penha, M. Maia, E. Dib, O. Magalhães Jr., E. Freymuller,
A. Maia, A. Príncipe (Sao Paulo)
Purpose: To evaluate the effects of subretinal injection of different concentrations and osmolarities
of indocyanine green (ICG), infracyanine (IF), trypan blue (TB), glucose (GL), supernatant
of triamcinolone Kenalog (STK) and preservative-free triamcinolone (PFT).
Methods: Forty-eight rabbits were divided in 4 subgroups of 12 animals submitted to subretinal
injection of:
Group A - 1) ICG 0.05% (279 mOsm); 2) TB 0.15% (312 mOsm); 3) GL 5% (280 mOsm) and BSS (300mOsm).
Group B - 1) ICG 0.046% (251 mOsm); 2) TB 0.13% (260 mOsm); 3) GL 5% (253 mOsm) and BSS (300mOsm).
Group C -1) STK 40 mg/ml (330 mOsm); 2) PFT 40mg/ml (285 mOsm) and 6) BSS (300mOsm).
Group D -1) ICG 0.05% (279 mOsm); 2) IF 0.5% (275 mOsm) and 3) BSS (300mOsm).
Animals were followed by 6, 12, 24 hours and 14 days after surgery by ophthalmoscopy, fluorescein angiography and histological
evaluation by light as well as transmission electron microscopy.
Results: Subretinal injection of ICG (270mOsm and 251mOsm) caused a severe damage to the phoreceptor inner segments
(PIS), photoreceptor outer segments (POS), outer nuclear layer (ONL) and retinal pigment epithelium (RPE) during the
whole follow-up. Subretinal injection of TB (312mOsm) resulted in minimal PIS and ONL abnormalities 24 hours and 14 days
after surgery, similar to subretinal IF (275mOsm) injection. Hypo-osmolar TB caused injury to POS, PIS, ONL as well as RPE
during the whole follow up. The fluorescein angiogram showed window defects in positions that ICG, IF and TB were injected
into the subretinal space, which were more prominent at the ICG subretinal area. Subretinal injection of PFT 40mg/ml
(285 mOsm) caused minimal damage of the POS, similar to subretinal injection of BSS and GL. The subretinal injection of
STK resulted in POS/ PIS and ONL injury 24 and 14 days following injection.
Conclusions: Subretinal injection of ICG 0.05% resuted in retinal damage, which was more important than subretinal TB
0.15% or 1.5 mg/ml injection. The damage induced by hypo-osmolar solutions was more important than iso-osmolar solutions.
The subretinal injection of IF 0.5% and TB 0.15% resulted in similar retinal damage. The subretinal injection of STK
resulted in more important damage than subretinal PFT. These findings emphasizes that care must be taken regarding the
solution osmolarity as well as to avoid subretinal migration of these substances during macular hole surgery.