Photoablation of inner limiting membrane and inner retinal layers using the Erbium:YAG-laser: an in vitro study.
OBJECTIVE
To explore the potential of Er:YAG-laser irradiation for precise and tractionless retinal tissue and inner limiting membrane ablation.


METHODS
We used free-running Er:YAG-laser irradiation (lambda = 2.94 microm) transmitted either through a 10 cm long low-OH-quartz fiber or a 2 m long sapphire fiber that produced a more homogenous light distribution at the fiber tip. Retinal ablation in porcine retinal explants was performed under air or perfluorodecaline (PFD). Ablation depth was evaluated by optical coherence tomography (OCT) and from histologic sections.


RESULTS
A radiant exposure of 5.0 J/cm(2) delivered through a low-OH-quartz fiber and PFD caused a complete transsection of the neurosensory retina. Radiant exposures between 3.5 and 2.0 J/cm(2) resulted in marked variations of ablation depth and adjacent thermal damage. By contrast, laser pulses of 4.0 and 3.0 J/cm(2) transmitted through the sapphire fiber produced more homogenous defect patterns and less thermal damage. Close to the ablation threshold, with 1.0-2.0 J/cm(2), ablation was limited to a 10-20 microm thin layer of the neural retina.


CONCLUSIONS
We achieved in vitro ablation of inner retinal layers, but could not produce selective and reproducible ILM removal.
Hoerauf
Hans
H
University Eye Clinic, Ratzeburger Allee 160, 23538 Luebeck, Germany. hanshoerauf@yahoo.com
Brix
Alexandra
A
Winkler
Jörg
J
Droege
Gerit
G
Winter
Christian
C
Birngruber
Reginald
R
Laqua
Horst
H
Vogel
Alfred
A
D000818:Animals; D004871:Erbium; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000295:instrumentation*; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation*; D012160:Retina / Q000601:surgery*; D013552:Swine
D004871:Erbium