Feeder Vessel Treatment with High Speed ICG
Angiography
Stanescu-Segall D1, 2,Coscas G1, Coscas F1, and Soubrane G1
1Créteil
Eye University Hospital, France
2Saint-Pierre Eye University Hospital, Belgium, Aspirant, Fonds
National de la Recherche Scientifique (F.N.R.S) of Belgium
Correspondence to: Gabriel Coscas, Centre ophtalmologique universitaire de
Créteil, 40 avenue de Verdun, 94010, Créteil, France.
Email: gabriel.coscas@libertysurf.fr
Accepted for publication: 18th August 2003
First Video
Segment: Feeder Vessel Before Treatment. This
High-Speed ICG is showing the rapid appearance and disappearance of an
infero macular feeder vessel (yellow arrow heads) feeding a subfoveal
neovascular membrane (green arrow heads). Second Video Segment: Feeder Vessel After Micropulsed Laser Treatment. This High-Speed ICG was performed after treatment by micropulsed laser on the feeder vessel. We can see the scar of the laser (green arrow heads) and the complete absence of the subfoveal neovascular membrane after the laser treatment. |
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Introduction
Evidence based guidelines for treatment of subfoveal choroidal neovascularization in age-related macular degeneration (ARMD) support the use of either subfoveal laser photocoagulation1 with specific criteria or photodynamic therapy with Vertoporfin (PDT.)2-4
Photocoagulation for subfoveal choroidal neovascularization typically results in immediate and permanent severe visual loss. No randomized clinical trials have been carried out comparing PDT and subfoveal laser treatment with PDT and perifoveal laser treatment.
Treatment of feeder vessels (FV) supplying the CNVM secondary to ARMD was initially recommended for patients presenting with a recurrent neovascular membrane on the scar of a previous treatment, but this treatment has rarely been successful in the past. The use of ICG videoangiography has allowed visualization of choroidal vessels at the choroidal arterial phase allowing for detection of feeder vessels located outside the fovea. High Speed ICG (HSICG) angiography permits the visualization of blood flow dynamics in the afferent feeder vessel of subfoveal CNV. Pilot studies have shown that feeder vessel closure by direct laser treatment (Krypton or Diode micropulse) in an extrafoveal position leads to regression of subfoveal CNVM without decrease in vision.5-9
Technique
The detection of feeder vessels was achieved by recording a high speed ICG (HSICG) movie with a scanning laser ophthalmoscope (Heidelberg Retinal Angiography {HRA}, Heidelberg Engineering, Heidelberg, Germany). One ml of ICG solution (25 mg diluted in 3ml of 5% glucose solution) was injected into the forearm vein followed by a rapid flush of 5 ml of glucose solution and 30 seconds of ICG recording. This technique of injection allows high-resolution images of the choroidal vasculature in the very early phase of ICG. The early images were recorded digitally at 12 images per second with a 30° field size and a screen resolution of 512 x 512 pixels. After acquisition of the images on ICG hardware, images were visualized as a movie with the Phi-motion system. The detection criterion for feeder vessels was evidence of thin vessels that fill and empty rapidly. When a feeder vessel was identified, laser treatment by micropulsed infrared laser was targeted to the extrafoveal portion of the feeder vessel. Immediately after laser treatment, a HSICG was repeated to visualize the feeder vessel closure. If FV closure was not confirmed, laser treatment was repeated until proven by HSICG.
Results
Our data confirmed the high rate of feeder vessel identification; the number of FV supplying a CNV varied from one to four with a mean number of 2.1. The mean number of laser treatments performed was 1.8. On a series of 34 patients we achieved a stabilization and/or improvement of vision in 86% of patients. Furthermore, the majority of patients did not require other treatments except in 3 patients (8%) who underwent PDT and 2 patients (5%) who received perifoveal laser treatment. The best results of FV treatment were obtained in subfoveal and juxtafoveal post-laser recurrences.
Comments
The early reports by Shiraga et al and Staurenghi et al showed that it was possible to identify and treat feeder vessels of classic CNVM by direct laser photocoagulation.6,7 Thereafter, Glaser et al extended feeder vessel treatment to occult CNVM.8 Pilot and retrospective studies have reported a high rate of identification of feeder vessels ranging from 80 to 100%, and closure of feeder vessels in most of the cases without early repermeabilization resulting in improvement of vision. The use of micropulsed diode laser allows reduction of blood flow in the feeder vessels with very localized and invisible ophthalmic lesions, since infrared energy is absorbed in the middle layers of the choroid8 where the feeder vessels are located. Blood flow dynamics are key in the identification of the afferent feeder vessels. HSICG makes is possible to analyze blood flow dynamics in the feeder vessels and to select the ideal treatment area. No other technique so far has allowed the identification of blood flow direction in the feeder vessels. Without identification of afferent FVs, inadvertent occlusion of draining vessels may have a risk of producing subretinal hemorrhage.
Feeder vessel treatment of subfoveal CNVM produces a smaller scotoma and spares the fovea. It allows also for a combination of other treatment modalities such as PDT, TTT or subfoveal laser photocoagulation. However, feeder vessel identification by HSICG and treatment by micropulsed laser involves a relatively high cost of equipment and has a steep learning curve. Promising early reports indicate that feeder vessel coagulation should be considered in cases of subfoveal CNV and randomized clinical trials are warranted.
Acknowledgements
This work was supported by the F.N.R.S of
Belgium.
References
Desatnik H, Treister G, Alhalel, et al. ICGA-guided laser photocoagulation of feeder vessels of choroidal neovascular membranes in age-related macular degeneration. Retina 2000;20:143–150.
Shiraga F, Ojima Y, Matsuo T, et al. Feeder vessel photocoagulation of subfoveal choroidal neovascularization secondary to age-related macular degeneration. Ophthalmology 1998;105:662–669.
Staurenghi G, Orzalesi N, La Capria A, et al. Laser treatment of feeder vessels in subfoveal choroidal neovascular membranes. A revisitation using dynamic indocyanine green angiography. Ophthalmology 1998;105:2297–2305.