Chronic and acute analysis of optic nerve sheath fenestration with the free electron laser in monkeys.
OBJECTIVE
The Amide II wavelength (6.45 microm) produced by the free electron laser (FEL) can efficiently create an optic nerve sheath fenestration in rabbits. We wished to determine if it would be equally successful in macaque monkeys and to determine the histopathologic changes between traditional scissors or knife optic nerve sheath fenestration to FEL fenestration.


METHODS
Optic nerve sheath fenestration was performed using either the FEL (6.45 microm, 30 Hz, 2-3 mJ, 325-microm spot size) through a hollow waveguide probe in 12 eyes or with a scissors or a knife in 6 eyes. The monkeys survived 1 month with the fellow optic nerve operated acutely just prior to sacrifice. Optic nerves were evaluated histologically.


RESULTS
Less tissue manipulation was required using the FEL surgical probe. Electroretinograms showed minimal or no change. Tissue responses using either method were similar following chronic or acute incisions. Mild upregulation of vimentin and glial fibrillary acid protein (GFAP) was seen in astrocytes adjacent to the fenestration, but no change in S100 beta was evident.


CONCLUSIONS
The FEL energy at 6.45 microm delivered through a hollow waveguide appears capable of efficiently and safely producing an optic nerve sheath fenestration in monkeys. This innovative surgical technique should be considered for human use.
Joos
Karen M
KM
Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee 37232-8808, USA. karen.joos@mcmail.vanderbilt.edu
Mawn
Louise A
LA
Shen
Jin H
JH
Casagrande
Vivien A
VA
D000818:Animals; D001253:Astrocytes / Q000473:pathology / Q000502:physiology / Q000528:radiation effects; D004195:Disease Models, Animal; D006801:Humans; D053685:Laser Therapy; D008253:Macaca mulatta; D009186:Myelin Sheath / Q000473:pathology* / Q000502:physiology / Q000528:radiation effects*; D009900:Optic Nerve / Q000473:pathology / Q000528:radiation effects* / Q000601:surgery*; D011559:Pseudotumor Cerebri / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D011817:Rabbits; D012160:Retina / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects