Ophthalmic seminars最新文献

The spectrum of migraine has been outlined with particular attention to two entities: Ophthalmoplegic Migraine and Periodic Migrainous Neuralgia. Although quite different in many respects from classical migraine, the relationship of a periodic localized vascular phenomenon giving rise to headache and transient neurologic signs, classify PMN and OPGM as migraine variants. Supportive of this concept, the literature has been reviewed in both entities, and some observations are made on the validity of earlier reports. It is the author's opinion that Raeder's syndrome should be reserved for patients with a lesion localizing in the paratrigeminal area. This does not exclude migraine as an etiologic agent but also recognizes tumors, infections and fractures as being more common.

Herpes zoster ophthalmicus is not an uncommon disease and is more prevalent among debilitated and seriously ill patients. It is caused by the same virus causing varicella. The exact trigger mechanism is unknown, as well as much of the pathogenesis. The disease is more uncommon among the elderly and usually runs a benign course. Approximately 50% of the patients develop ocular complications ,the most frequent of these being keratitis, iritis, secondary glaucoma and extraocular muscle involvement. The most striking pathologic features are the lymphocytic infiltration of the long ciliary nerves and the vasculitis of the vessels accompanying them. The most controversial aspect of the disease is that of treatment. Almost every therapeutic regimen has been attempted in a disease whose natural course is self-limited. The future will add more to our knowledge of the pathogenesis of the disease and shed more light on the efficacy of various treatments.

Mechanisms of accomodation among Vertebrates vary with phylogeny, structure of the eye, and feeding habits. Some vertebrate eyes are so small as to possess a large depth of field, while others with larger eyes have structures that circumvent the need for an active lenticular focusing mechanism. Cyclostomes and Teleosts are myopic and move the lens backward to accommodate for distance. Selachians, Amphibians, and Snakes are hypermetropic and move the lens forward to accommodate for near. Birds and Reptiles have powerful mechanisms that compress the lens to accommodate for near. Amphibious vertebrates have the greatest accommodative amplitudes of all. The mammalian mode of accommodation is relatively new in the phylogenetic sense. It is poorly developed in most forms except primates, the most advanced of which is man's. The Helmholtz theory of accommodation remains widely accepted. Upon contraction of the ciliary muscle, zonular tension on the lens is released, and capsular elasticity molds the lens into a more spherical shape. Loss of capsular elasticity and hardening of the nucleus account for most of the decrease in accomodation with age.

Wilson's disease, or hepatolenticular degeneration, is a rare inherited disorder of copper metabolism which usually affects young people. Excess copper accumulates in the tissues, primarily in the liver, brain, and cornea. This copper deposition results in a wide range of hepatic and neurological symptoms, and may produce psychiatric illness. Hepatic involvement often occurs in childhood, while neurological deficits generally are detected at a later age. The disease is inherited in an autosomal recessive fashion. Ocular findings are of particular importance because the corneal copper deposition, forming the Kayser-Fleischer ring,is the only pathognomonic sign of the disease. The structure of the ring and the presence of copper have been well established. An anterior capsular deposition of copper in the lens results in a characteristic sunflower cataract in some of these patients. Other ocular abnormalities have been described but are much less common. The pathogenesis of the disease and the basic genetic defect remain obscure. It is clear that there is excess copper in the tissues, but the mechanism of its deposition is unknown. It is in some way associated with a failure to synthesize the serum copper protein ceruloplasmin normally. Another theory suggests that an abnormal protein with a high affinity for copper may bind the metal in the tissues. The diagnosis may be suggested by the clinical manifestations and confirmed by the presence of a Kayser-Fleischer ring. In the absence of these findings biochemical determinations are necessary. The most important of these are the serum ceruloplasmin, the urinary copper, and the hepatic copper concentration on biopsy. Treatment consists in the administration of the copper chelating agent, penicillamine, and the avoidance of a high copper intake. This usually results in marked clinical improvement if irreversible tissue damage has not occurred. Maintenance therapy for life is necessary in order to continue the negative copper balance. The detection and prophylactic treatment of asymptomatic individuals with the disease is especially important. Seven cases of Wilson's disease have been presented in order to illustrate many of the features which have been discussed, with emphasis on the ocular findings.