Optic nerve damage

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Recent Advances Bring Treatment for Optic Nerve Damage Within Sight

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NEW YORK (Reuters Health) Jan 04 - Experimental advances in nerve

protection, regeneration, and repair should soon make possible the

restoration of sight in patients affected by optic nerve damage, asserts

s Hopkins Hospital researcher Dr. Neil R. .

" Any type of damage to the optic nerve could potentially be amenable to

treatment, " Dr. told Reuters Health. " We hope to preserve or restore

vision to patients of virtually any age. " This includes patients with optic

nerve trauma, hereditary or metabolic problems, optic neuritis, glaucoma,

and ischemic optic neuropathy. " It's not inconceivable that we could even

treat optic nerve problems in utero, " he added.

Apoptosis plays a major role in cell death after optic nerve injury, the

Baltimore-based researcher notes in the December issue of the American

Journal of Ophthalmology. Several methods have the potential to prevent or

stop apoptosis, he writes. Among these are the application of inhibitors of

glutamate and nitric oxide to prevent their toxic effects when released from

injured retinal ganglion cells.

Alpha-2-adrenoreceptor agonists, such as brimonidine; nerve growth factors;

and heat shock proteins can be applied to protect retinal ganglion cells.

There is also evidence that vaccination with nonencephalitogenic peptides

can protect eyes at risk for optic neuropathy.

Dr. said these agents could be administered orally, by injection, or

by surgically exposing the optic nerve to bathe it in a therapeutic agent.

However, the most clinically feasible method, he said, would be " to inject

directly into the eye and ensure selective take-up of the material by

ganglion cells of the retina. "

Transected nerves require an environment that will allow regeneration of the

axon. One way to produce such an environment is to eliminate such inhibitory

factors as myelin and myelin breakdown products. Dr. also suggests

provision of external growth factors, such as fibroblast growth factor and

neurotrophins, to the external milieu of the axon.

In addition, molecules that guide the axons through the optic chiasm so that

they synapse in the correct locations within the brain include netrins,

ephrins, cadherins, and integrins.

Finally, he writes, stem cells " could replace the dead or damaged retinal

ganglion cells, provide the enzymatic machinery to correct congenital or

acquired metabolic defects, deliver tropic or trophic support to neural

cells, provide cellular bridges among disconnected cells, or even deliver

toxic substances to abnormally proliferating cells within the optic nerve. "

" This is truly one of the most frustrating parts of ophthalmology, " Dr.

told Reuters Health. " We can diagnose optic nerve conditions very

well, but of all the various types of eye problems, this is the one area

where treatment is incredibly lacking. "

He concluded, " Only with the teamwork of physicians, drug companies, and the

federal government can we solve this problem. But solve it we will. " Dr.

hopes to see significant progress toward clinical trials within the

next decade.

Am J Ophthalmol 201;132:811-818.