Effects of subretinal injections of indocyanine green, trypan blue, and glucose in rabbit eyes.
OBJECTIVE
To evaluate the effects of subretinal injections of indocyanine green (ICG), trypan blue, glucose (GL), and balanced salt solution (BSS) in rabbits.


METHODS
Experimental study.


METHODS
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.


METHODS
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.
Penha
Fernando M
FM
Department of Ophthalmology-Vision Institute, Federal University of São Paulo, São Paulo, Brazil. penhaepm@yahoo.com.br
Maia
Mauricio
M
Eid Farah
Michel
M
Príncipe
André H
AH
Freymüller
Edna H
EH
Maia
André
A
Magalhães
Octaviano
O
Smith
Ricardo L
RL
D000085:Acetates; D000818:Animals; D004396:Coloring Agents / Q000633:toxicity*; D004338:Drug Combinations; D005260:Female; D005451:Fluorescein Angiography; D005947:Glucose / Q000633:toxicity*; D007208:Indocyanine Green / Q000633:toxicity*; D007267:Injections; D008903:Minerals; D009900:Optic Nerve / Q000473:pathology; D009994:Osmolar Concentration; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000473:pathology; D012965:Sodium Chloride; D014343:Trypan Blue / Q000633:toxicity*; D014821:Vitrectomy
D000085:Acetates; C030660:BSS solution; D004396:Coloring Agents; D004338:Drug Combinations; D008903:Minerals; D012965:Sodium Chloride; D014343:Trypan Blue; D007208:Indocyanine Green; D005947:Glucose