Effects of indocyanine green on the retina and retinal pigment epithelium in a porcine model of retinal hole.
OBJECTIVE
This study was designed to emulate human macular hole surgery and to test the effects of indocyanine green (ICG) on the retina and retinal pigment epithelium (RPE).


METHODS
Yorkshire Cross pigs (n = 23) underwent vitrectomy, separation of the posterior cortical vitreous, and creation of a single retinal hole. In three study groups (n = 6, each group), air-fluid exchange was performed, following which balanced salt solution (BSS), 1.0% ICG, or 0.5% ICG was applied over the retinal hole. In one additional group (n = 5), 0.5% ICG was injected into the fluid-filled eye. At 4 weeks, the eyes were examined clinically, and fundus photographs were obtained before enucleation and light microscopic examination.


RESULTS
Clinical evaluations documented a statistically significant difference between study groups (P = 0.036). There was a higher rate of moderate or severe RPE atrophy among animals where 1% or 0.5% ICG was applied in air-filled eyes (83% and 67%, respectively) compared with BSS controls (17%) and fluid-filled eyes receiving 0.5% ICG (40%). Histologic evaluation demonstrated a statistically significant difference between groups (P = 0.044), with extensive outer retinal degeneration observed in air-filled eyes receiving 1% or 0.5% ICG (66% and 60%, respectively) compared with BSS controls or fluid-filled eyes receiving 0.5% ICG (none of the eyes in either group). None of the study groups had any changes in the inner retina except at the retinal hole site.


CONCLUSIONS
Retina exposed to ICG concentrations used in human vitreoretinal surgery had greater RPE atrophy and outer retinal degeneration than control eyes undergoing the same surgery without ICG. Eyes filled with infusion fluid during ICG injection had less damage to the RPE and outer retina than did air-filled eyes receiving ICG.
Czajka
Marcin P
MP
Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27710, USA.
McCuen
Brooks W
BW
Cummings
Thomas J
TJ
Nguyen
Hoang
H
Stinnett
Sandra
S
Wong
Fulton
F
D000388:Air; D000818:Animals; D001284:Atrophy; D004396:Coloring Agents / Q000008:administration & dosage / Q000009:adverse effects*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005654:Fundus Oculi; D007208:Indocyanine Green / Q000008:administration & dosage / Q000009:adverse effects*; D007267:Injections; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000473:pathology; D012160:Retina / Q000187:drug effects* / Q000473:pathology; D012167:Retinal Perforations / Q000473:pathology*; D012965:Sodium Chloride; D013552:Swine
D004396:Coloring Agents; D012965:Sodium Chloride; D007208:Indocyanine Green