[Retinal photoablation with the Erbium:YAG laser. Initial experimental results for traction-free removal of tissue].
BACKGROUND
To investigate the potential of an Er:YAG laser for precise and traction-free removal of retinal layers in vitro.


METHODS
Retinal ablation in porcine retinal explants was performed using a free running Er:YAG laser focused either into a low-OH quartz fiber or a sapphire fiber. The explants were treated under air or perfluorodecaline (PFD). The ablation depth was evaluated by optical coherence tomography (OCT) and histology sections.


RESULTS
A radiant exposure of 5.0 J/cm(2) under air and PFD resulted in complete transsection of the neurosensory retina. Between 3.5 and 2.0 J/cm(2) the ablation depth and the defect patterns varied markedly and adjacent thermal zones areas were seen. Below 2.0 J/cm(2) no defects could be created in air, whereas under PFD the ablation extended into the ganglion cell layer. Ablations using a sapphire fiber and 2.0 J/cm(2) showed a significantly higher reproducibility of ablation depth, and homogeneous defect patterns limited to the nerve fiber layer could be produced without thermal damage.


CONCLUSIONS
The Er:YAG laser system with a low-OH quartz fiber allowed ablation of inner retinal layers in vitro, but revealed a variable ablation depth and low reproducibility.However, a sapphire fiber showed markedly improved results. Therefore its use during vitreoretinal surgery seems possible not only as a cutting device but also as a tool for the ablation of fine retinal structures.
Hoerauf
H
H
Klinik für Augenheilkunde, Universitäts-Augenklinik Lübeck. hhoerauf@ophtha.mu-luebeck.de
Brix
A
A
Scholz
C
C
Winkler
J
J
Dröge
G
G
Birngruber
R
R
Vogel
A
A
Laqua
H
H
D000818:Animals; D004871:Erbium; D005466:Fluorocarbons; D053685:Laser Therapy / Q000379:methods*; D013508:Ophthalmologic Surgical Procedures; D012160:Retina / Q000033:anatomy & histology / Q000601:surgery*; D013552:Swine; D014054:Tomography
D005466:Fluorocarbons; D004871:Erbium