ICG Dye Enhanced Photocoagulation of Feeder Vessels for CNV

Abstract

Abstract: : Purpose: This study investigates the use of intravenously injected ICG dye to augment 810 nm diode laser photocoagulation closure of choroidal feeder vessels in the treatment of CNV. A combination high-speed infrared digital fundus camera and laser aiming system was used to precisely deliver photocoagulation energy to feeder vessels during passage of a concentrated ICG dye bolus. Methods: Patients with macular degeneration and choroidal neovascular complexes identified with fluorescein angiography were evaluated with high-speed ICG angiography. Candidate arterial feeder vessels with diameters less than 200µm were identified in 7 eyes. The feeder vessels were treated with a 810 nm wavelength diode laser at a power of 0.6 watt for 1.0 second, delivered during peak transit of an intravenously injected 50mg ICG dye bolus. Transit of the ICG dye bolus through targeted feeder vessels was monitored with a fundus camera modified to perform high-speed ICG angiography and real-time delivery of an 810 nm laser photocoagulation beam. One to three applications of photocoagulation laser energy were needed to achieve closure of each candidate feeder vessel during a single dye bolus transit. Closure of the feeder vessel was determined by cessation of ICG dye flow imaged in real time or by the appearance of ICG dye trapped in the targeted vessel. Results: Feeder vessels were successfully closed in 6 of 7 eyes (86%) with subsequent reduction in leakage observed clinically and on fluorescein angiography in 4 of these 6 eyes (67%). Improved visual acuity was noted in these 4 eyes (average 2 Snellen lines). No adverse events occurred during or following treatment. Re-treatment of feeder vessels was required in 3 of the successfully treated patients during a six month follow-up period because of recurrent subretinal fluid and decreased vision. The same vessels were closed easily with re-treatment using the same dye-enhanced photocoagulation parameters. Conclusion: Successful feeder vessel closure is possible using ICG dye-enhanced photocoagulation. This treatment modality allows treatment of multiple candidate CNV feeder vessels following a single injection of ICG dye. The energy required to close feeder vessels using dye enhanced photocoagulation was from 0.6 to 1.8 joules. This is in contrast to the 24+ joules required to successfully close feeder vessels using 810 nm wavelength laser photocoagulation without ICG dye co-administration. Future studies will investigate the maintenance of feeder vessel closure and the efficacy of ICG dye-enhanced photocoagulation.

Keywords: 308 age-related macular degeneration • 346 choroid: neovascularization • 454 laser