Transpupillary thermotherapy for occult subfoveal neovessels in age-related macular degeneration: importance of patient pigmentation for the determination of laser settings

BACKGROUND: Presently the indication for transpupillary thermotherapy (TTT) is the treatment of retrofoveal occult subretinal neovascular membranes (OSRNM) for which PDT (photodynamic therapy) has a limited effect. The diode laser power settings given by the manufacturer (Iridex Co, Mountain View, California) have to be modulated according to several criteria including patient pigmentation. The purpose here was to report on a group of patients that presented chorioretinal atrophy after TTT. METHODS: Thirty-eight eyes of 37 patients with OSRNM due to age-related macular degeneration underwent TTT. Indications to treat were diffuse exudative membranes, limited subfoveal OSRNM with a visual acuity of less than 0.4, or a drop of visual acuity of 3 Snellen lines or more since the previous examination. Dual fluorescein and indocyanine green angiography were used for angiographic follow-up. Treatment was performed according to the manufacturer's parameters. The group of patients that presented chorioretinal atrophy after TTT was analysed in this study RESULTS: Five patients presented a limited or spot-size related post-TTT chorioretinal atrophy. Pre-laser visual acuity was 0.34 +/- 0.13 and post-TTT visual acuity was 0.25 +/- 0.15. The OSRNM had disappeared in all cases. The common denominator in these patients was that they were white haired but upon questioning all happened to be dark-haired in their youth. CONCLUSIONS: Evolution towards atrophy can occur after TTT and probably depends on several factors. We showed that pigmentation is a parameter to be evaluated carefully before TTT and that laser power settings should progressively be diminished with increasing patient pigmentation. In white haired persons the original pigmentary status should be part of the patient history.