Experimental selective choriocapillaris photothrombosis using a modified indocyanine green formulation

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Cardillo, J. A. [UNIFESP]
Jorge, R.
Costa, R. A.
Nunes, S. M. T.
Lavinsky, D. [UNIFESP]
Kuppermann, B. D.
Tedesco, A. C.
Farah, M. E. [UNIFESP]
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Background: This in vivo study assessed and compared the effectiveness of an aqueous indocyanine green (ICG) formulation (R-ICG) and a lipid ICG formulation (L-ICG) in occluding the rabbit choriocapillaris, and determined the singlet oxygen quantum yields and aggregation properties of both formulations in vitro.Methods: Singlet oxygen production and aggregation were compared. the eye fundus of 30 albino rabbits was irradiated 0-15 min after dye injection using an 810 nm diode laser. Fluorescein angiography and light microscopy were used to evaluate the safety and efficacy of R-ICG and L-ICG.Results: L-ICG decreased the dimerisation constant and the tendency of ICG to form aggregates, and increased the efficiency of ICG in generating singlet oxygen (R-ICG, Phi Delta= 0.120 and L-ICG, Phi Delta= 0.210). Using a 10 mg/kg dose, choriocapillaris occlusion was achieved at a light dose of 35.8 J/cm(2) with L-ICG and 71.6 J/cm(2) with R-ICG with minimal damage to the neurosensory retina.Conclusion: Restrictions to the use of ICG in aqueous solution, low singlet oxygen quantum yields and high aggregation tendency, were overcome with L-ICG. the lower laser irradiance required to obtain choriocapillaris occlusion may suggest that L-ICG is a more potent and selective photosensitiser than R-ICG.
British Journal of Ophthalmology. London: B M J Publishing Group, v. 92, n. 2, p. 276-280, 2008.