Laser photocoagulation has evolved substantially since its introduction. Emphasis is now placed more on laser techniques that spare the retinal structures and limit collateral damage. Previously, laser surgeons used relatively intense yellow-white lesions that could easily be seen directly after placement, either for panretinal photocoagulation or for ablation of choroidal neovascular membranes. These lesions were all well above threshold, ie, beyond the intensity at which they would be barely detectable in the retina during treatment. Efforts to improve visual outcomes have incorporated substantially less intense lesions, including clinically undetectable subthreshold lesions. The effects of subthreshold laser treatment on drusen resorption in age-related macular degeneration is being studied as part of a clinical trial (Prophylactic Treatment of Age-Related Macular Degeneration).1 Such treatment has also been used for diabetic macular edema and even proliferative diabetic retinopathy.2 Proof of therapeutic efficacy of these interventions is not yet irrefutable, although a few early reports have been published.
Friberg TR, Roider J. Subthreshold Laser Photocoagulation and Criminal Fraud. Arch Ophthalmol. 2003;121(9):1343. doi:10.1001/archopht.121.9.1343-a