J. M. Gordon and colleagues, in their Brief Communication “Surgery by sunlight on living animals” (Nature 424, 510; 200310.1038/424510a), describe the use of a solar photocoagulator to necrose a rat liver lesion in what they believe to be “the first time that intense incoherent light has been applied successfully in an interstitial medical procedure”. They may be surprised to learn that such a technique played a significant role in the development of a modern clinical ophthalmic practice: retinal photocoagulation. The German ophthalmologist Gerhard Meyer-Schwickerath (G. Meyer-Schwickerath Ber. Dtsch. Ophthalmol. Ges. 55, 256–259; 1949) not only undertook the repair of retinal breaks by focused sunlight, but also designed the optical instrumentation that bears his name: the Meyer-Schwickerath coagulator.