Differential injury and repair of the rod and cone cells following exposure to argon laser was studied by light and electron microscopy in two groups of lesions. In the mild lesions (13 or 15 to 21 mw), nuclei and outer segments of cone cells appeared to suffer more disruptive changes than those of the adjacent rod cells. In the severe lesions (41 to 55 mw), both rod and cone cells were necrotic in the acute stage in the central area of the lesions, but, during the recovery, the rod cells and their photoreceptor elements in the periphery of the lesions recovered and there was selective loss of cone elements. Rod cells in the periphery of the lesion prolapsed into the lesion as the necrotic cells were being removed.
Tso MOM, Wallow IHL, Powell JO. Differential Susceptibility of Rod and Cone Cells to Argon Laser. Arch Ophthalmol. 1973;89(3):228-234. doi:10.1001/archopht.1973.01000040230014