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The eye of a 47 year old man with tyrosinase-positive oculocutaneous albinism, photophobia, nystagmus and visual acuity 0, 4-0, 5 was histologically examined after orbital exenteration for neoplasia. Histologic serial sections of the centre of the retina showed a continuous 6-8 cell-layer of ganglion cells, without any suggestion of a foveolar pit. The outer layers of the macular retina were altered secondarily by tumor-impression-folds; they were unremarkable at the periphery as were the acid mucopolysaccharides in the receptor region. Electron microscopy of the uvea and the retinal pigment epithelium showed a normal number of pigment granules but a deficiency of melanin, as well as structural anomalies. The absence of the foveolar pit and the decrease of visual acuity in tyrosinase-positive albinism is caused by definite morphologic alteration in the arrangement of ganglion cells in the macular region in the sense of a foveolar aplasia. The etiology is discussed. An identic anomaly has been described in aniridia, similar ones in other congenital ocular diseases.

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After laser irradations, retinas of 13 rabbits were examined by electron microscope. The laser focus was set between 30 min and 140 h or 6 weeks in advance. The anatomical separation between the retina and the connective tissue of the choriocapillary in all the lesions is preserved by an intact Bruch's membrane. Destruction of the pigment epithelium, rod layer, and outer granular layer occurs in the early stages after coagulation. Later the nuclei of the rods show various stages of degeneration with simultaneous increases in the volume of the Müller's cells. The cytoplasma of the Müller's cells penetrates the nuclei of the sensory cells undergoing degeneration. Proliferation of the pigment epithelium begins after about 20 h. The first appearance of macrophages in the retina is visible after 30 h. Between 92 and 140 h in the area of the pigment epithelium, variously differentiated cells, which partly contain pigment granules and lamellary inclusion bodies, form. Some cells or cell groups which are visible might represent histiocytes within the Bruch's membrane 35, 45, 68, and 92 h as well as 6 weeks after coagulation. They partly cross the outer layer of the Bruch's membrane and neighboring connective tissue of the choroid. According to our studies, pigment epithelial cells, choroidal histiocytes, and Müller's cells participate in the phagocytosis.