Molteno implants and operating microscope-induced retinal phototoxicity. A clinicopathologic report. The right eye of a 75-year-old man with a history of cataract extraction, three penetrating keratoplasties, laser trabeculoplasty, two Molteno implants, and an operating microscope-induced retinal phototoxic lesion was studied post mortem. Histopathologic examination of the anterior segment showed evidence of penetrating keratoplasty, cataract surgery, and two Molteno implants with minimal associated tissue response. Ultrastructural examination showed a loose collagenous matrix surrounding the Molteno reservoirs, suggesting aqueous percolation from the reservoirs into the conjunctiva. Posteriorly, in the area of the phototoxic operating microscope-induced lesion, a nodule of retinal pigment epithelial hyperplasia with overlying atrophy of the photoreceptor cell layer of the neurosensory retina was noted. The retina also contained cystoid macular edema and an extensive preretinal membrane that was clinically unexpected. 