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Abstract
Colchicine is known to inhibit axoplasmic transport in ganglion cells. Previous studies have shown considerable, but largely reversible, retinal changes after low dosages of intravitreal colchicine in experimental animals. In the present study, the effects of 1.0 to 100 micrograms of intravitreal colchicine in monkeys were studied by ophthalmoscopy, light microscopy, and electron microscopy. Optic atrophy was ophthalmoscopically evident within 4 weeks after a single dose of 10 micrograms or more. Morphologic changes included progressive swelling of retinal neurons, accumulation of a fibrillogranular material, displacement of organelles, and loss of microtubules. Plasmalemmal rupture was observed in ganglion cells and in photoreceptors after as little as 1 microgram of colchicine. Relative sparing of the cone cells was noted. The retina of monkeys appears to be more sensitive to intravitreal colchicine than that of certain lower animals.