Fig. 91. Tissue changes induced by a ruby laser. A. Accidental macular injury from reflected ruby laser beam caused a macular burn that reduced visual acuity to 20/100. B. Coagulative necrosis of the retinal pigment epithelial cells characterizes the region of retinal injury. Areas of focal densification (arrows) are present within the retinal pigment epithelial cell and within the outer segments of the adjacent photoreceptors. R, rod; C, cone; bm, thin basement membrane of the retinal pigment epithelium; ch, choriocapillaris. (× 12,000.) Inset 1. A mild lesion limited to the retinal pigment epithelial cells produced by a ruby laser. (PD stain; × 395.) Inset 2. Alterations in the photoreceptor outer segments. (× 25,000.) C. Transition between the region of mildly injured pigment epithelial cells and normal retinal pigment epithelial cells. (× 12,000.) (A from Curtin TL, Boyden DG: A, J Ophthalmol 65:188, 1968; inset 1 and C from Fine BS, Geeraets WJ: Acta Ophthalmol 43:684, 1965.)