Purpose: To clarify the evolution of laser scars and factors that possibly affect progression of laser-induced chorioretinal atrophy.
Methods: The authors quantified 191 areas of laser scarring from panretinal photocoagulation in 19 eyes with diabetic retinopathy and calculated the expansion rate of the laser scars. They also analyzed factors affecting expansion, including location, laser wavelength, and follow-up period. The follow-up period ranged from 36 to 122 months (mean, 62 months).
Results: Most (89.5%) laser scars gradually increased in size. The mean annual expansion rates were 12.7% in the posterior pole and 7.0% in the midperiphery. The annual expansion rate (16.5%) more than 4 years (late period) after treatment was higher than that (8.8%) within 4 years of treatment (early period). The expansion rate was minimal (1.2%) after argon laser treatment, whereas it was 11.7% after treatment with a 590-nm wavelength laser and 15.8% after treatment with a 610-nm wavelength laser.
Conclusion: Laser photocoagulation causes relentless expansion of laser scars over a long period. Laser scars enlarged more in the posterior pole. Lasers of a longer wavelength contributed to larger areas of chorioretinal atrophy.