The effect of chronic ischemia on the primate optic nerve.
OBJECTIVE
To develop an in vivo model of chronic optic nerve ischemia to study the role of vascular insufficiency in the development of glaucomatous optic neuropathy.


METHODS
We surgically implanted osmotically-driven mini-pumps that allowed the continuous micro-application of 0.2 micrograms/day of endothelin-1 (ET-1) into the retrobulbar optic nerve of rabbits and rhesus monkeys. ET-1 was delivered for 2 to 6 months, following which histological studies were performed.


RESULTS
Both rabbits and primates experienced a 35% to 38% decrease in optic nerve blood flow with corresponding focal narrowing of the vessels supplying the optic nerve. In the rabbit model, optic disc excavation and histologic tissue loss in the anterior optic nerve resulted from the induced ischemia.


CONCLUSIONS
Chronic ischemia of the primate anterior optic nerve induced with endothelin-1 infusion resulted in diffuse loss of axons without a change in the intraocular pressure.
Cioffi
G A
GA
Devers Eye Institute, Portland, Oregon, USA.
Sullivan
P
P
D000818:Animals; D001369:Axons / Q000473:pathology; D002908:Chronic Disease; D019332:Endothelin-1; D005901:Glaucoma / Q000209:etiology* / Q000473:pathology; D015918:Infusion Pumps, Implantable; D007511:Ischemia / Q000139:chemically induced / Q000150:complications*; D008253:Macaca mulatta; D009898:Optic Disk / Q000473:pathology; D009900:Optic Nerve / Q000098:blood supply* / Q000187:drug effects; D009901:Optic Nerve Diseases / Q000209:etiology* / Q000473:pathology; D011817:Rabbits
D019332:Endothelin-1