Treatment Of Various Ocular Diseases Research Articles

Nitric oxide in the eye: Multifaceted roles and diverse outcomes

Recent works have highlighted the role of nitric oxide in a wide array of disease entities, including septic shock, hypertension, cerebral ischemia, and chronic degenerative diseases of the nervous system. The functions of nitric oxide appear very diverse, having actions on vascular tone, neurotransmission, immune cytotoxicity, and many others. Nitric oxide is an important mediator of homeostatic processes in the eye, such as regulation of aqueous humor dynamics, retinal neurotransmission and phototransduction. Changes in its generation or actions could contribute to pathological states such as inflammatory diseases (uveitis, retinitis) or degenerative diseases (glaucoma, retinal degeneration). Localization in the eye and biochemical characteristics of nitric oxide will be reviewed. A better understanding of the nitric oxide pathway will be the key to the development of new approaches to the management and treatment of various ocular diseases.

β-Galactosidase transgene expression in transplanted rabbit retinal pigment epithelial cells in vivo

Intraocular transplantation of genetically modified cells that release a particular substance could have a major impact on the treatment of various ocular diseases. We studied the expression of the reporter gene beta-galactosidase (lacZ) in transplanted retinal pigment epithelial (RPE) cells in vivo. RPE cells from pigmented rabbits were transduced with the beta-galactosidase gene in a retroviral vector. Cells were then assayed for gene expression and transplanted subretinally into the eyes of New Zealand White rabbits. RPE cells that were transduced with a similar vector without the beta-galactosidase gene were used as controls. Rabbits were killed on days 1, 7, and 21 and the eyes processed for transmission electron microscopy Neomycin-resistant rabbit RPE cells that showed beta-galactosidase activity were generated within 2-5 weeks. After transplantation, viable RPE cells that expressed the transgene and that phagocytosed rod outer segments were observed on days 1, 7, and 21 The results show that generation of genetically modified RPE cells is feasible and that the transplanted cells remain viable and continue to express the transgene in the subretinal space of the host animal for at least 21 days. Transplantation of such genetically modified RPE cells could provide a new tool for studying retinal diseases and, potentially, for correcting metabolic abnormalities in retinal degenerations and dystrophies.

CRYOTHERAPY IN OCULAR DISEASE

The eye, the only organ normally exposed in subzero climates, shows a remarkable tolerance to severely low temperatures. In the development of new approaches to the treatment of various ocular diseases, cryotherapy has taken advantage of this resistance to cold. Low-temperature techniques have now been applied to the treatment of cataracts (cryoextraction), retinal detachment (cryopexy), glaucoma ( cryocyclotherapy ), and dendritic keratitis, as well as to obliterate vascular lesions of the eye. In 1961, Krwawicz¹first reported the technique of cryogenic cataract extraction. This provided an impetus for American ophthalmologists to develop new and improved instruments, using various cryogens, and quickly established the value and superiority of cryoextraction over older methods. Cryoextraction provides better control and maneuverability in cataract removal, since there is no sounder mechanical principle for grasping the lens than the intralenticular fusion provided by superfreezing. This procedure distributes the tractive force over the entire lens, so that the

LOCAL USE OF VITAMIN A PREPARATIONS IN OPHTHALMIC PRACTICE

The local application of vitamin A is of greater significance in the field of ophthalmology than is oral or intramuscular administration. In moderate climates this method of application of vitamin A does not extend to the general avitaminoses (keratomalacia and similar diseases). Such conditions are rare in Hungary. The aspecific action of this vitamin consists of epithelization and protection of the epithelium. It is not impossible that some conditions which respond to this form of therapy are due to local vitamin deficiency without being a general avitaminosis. It has always been a custom among laymen to apply milk and butter to the eye for the treatment of various ocular diseases irrespective of their etiology ; nevertheless, such treatment must now be considered as local vitamin therapy, although sometimes it is falsely indicated. The mysterious cure of Tobias' disease (serpent ulcer?), which was effected by the local application of fish liver, may