Laurence-Moon-Biedl syndrome, with certain mitochondrial diseases (Kearns-Sayre syndrome, Chap. 37), and with a number of degenerative and metabolic diseases (e.g., Refsum disease) of the nervous system. Another early life hereditary retinal degeneration, characterized by massive central retinal lesions, is the autosomal recessive Stargardt form of juvenile tapetoretinal degeneration. Like retinitis pigmentosa, Stargardt disease may be accompanied by progressive spastic paraparesis or ataxia. Nonpigmentary retinal degeneration is a feature of a number of rare syndromes and diseases, such as neuronal ceroid lipofuscinosis, Bassen-Kornzweig disease, Batten-Mayou disease, and others (see Chap. 36).
Toxic effects of medications are an important cause of retinal damage. Phenothiazine derivatives, less often used in practice than they had been, may conjugate with the melanin of the pigment layer, resulting in degeneration of the outer layers of the retina and a characteristic “bull’s-eye retinopathy” observed by fluorescein angiography. If these drugs are administered in high dosages for protracted periods, the patient should be tested for defects in visual fields and color vision. Among drugs used to treat neurologic disease, the antiepileptic drug vigabatrin is notable for causing retinal degeneration and a concentric restriction of the visual fields in almost half of exposed patients. Elevated levels of gamma-aminobutyric acid (GABA) in the retina are presumably the cause of toxicity. High-dose tamoxifen has caused toxicity in the retina, characterized by the deposition of refractile opacities and in more severe cases, by macular edema.
A cancer-associated retinopathy (CAR) has been described in patients with small-cell lung cancer and other tumors as a paraneoplastic illness (see Chap. 30). The typical presentation is of positive visual phenomenon and rapid bilateral visual loss. Antibodies against the recoverin protein, which modulates rhodopsin kinase, have been demonstrated in the serum of affected patients (Grunwald et al; Kornguth et al; Jacobson et al). A melanoma-associated retinopathy (MAR) that produces night blindness and affects primarily rods has also been described. These paraneoplastic processes are further described in Chap. 30.
Certain lysosomal diseases of infancy and early childhood are characterized by an abnormal accumulation of undegraded proteins, polysaccharides, and lipids in cerebral neurons, as well as in the macula and other parts of the retina (hence the terms storage diseases and cerebromacular degenerations). Corneal clouding, cherry-red spot and graying of the retina, and later optic atrophy are the observed ocular abnormalities. Chapter 36 discusses these diseases.