Optic nerve sheath fenestration with a novel wavelength produced by the free electron laser (FEL).
OBJECTIVE
To determine whether 6.45-microm free electron laser (FEL) energy can successfully perform optic nerve sheath fenestration and to compare the acute and chronic cellular responses with this surgery.


METHODS
Optic nerve sheath fenestration was performed in rabbits by using either FEL energy (< 2.5 mJ, 10 Hz, 325-microm spot size) or a knife. The optic nerve integrity and glial response were evaluated histologically acutely or 1 month postoperatively.


RESULTS
The FEL at low energy effectively cut the optic nerve sheaths with minimal reaction in the underlying nerve. With FEL or knife surgical techniques, a mild astrocytic hypertrophy only adjacent to the fenestration was observed acutely in the glial fibrillary acidic protein (GFAP) -immunoreacted sections. The chronic healing responses after either technique appeared similar with: (1) a thin fibrous scar at the fenestration site, (2) cells uniformly distributed (hematoxylin and eosin), and (3) up-regulation of GFAP and S100beta in astrocytes adjacent to the fenestration site.


CONCLUSIONS
The FEL at low energy performs an optic nerve sheath fenestration in a small space with ease. Both FEL and knife incisions cause a similar rapid glial response near the fenestration site that remains 1 month later.
Joos
K M
KM
Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee 37232-8808, USA. karen.joos@mcmail.vanderbilt.edu
Shen
J H
JH
Shetlar
D J
DJ
Casagrande
V A
VA
D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006984:Hypertrophy; D007150:Immunohistochemistry; D053685:Laser Therapy / Q000379:methods*; D009898:Optic Disk / Q000473:pathology; D009900:Optic Nerve / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D011817:Rabbits; D012160:Retina / Q000473:pathology; D015854:Up-Regulation; D014945:Wound Healing
D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein