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Erbium:YAG laser cataract removal: role of fiber-optic delivery system
1Medical College of Virginia, Virginia Commonwealth University, Richmond, USA.
Purpose:
To review the properties of energy delivery systems and to evaluate the efficiency of zirconium-fluoride-based and sapphire fibers delivering erbium:YAG (Er:YAG) laser energy in a clinical laser cataract surgery system.
Setting:
Department of Ophthalmology, Medical College of Virginia Campus of Virginia Commonwealth University, and Veterans Affairs Medical Center, Richmond, Virginia, USA.
Methods:
Thirty-two patients had Er:YAG laser cataract extraction. Preoperative visual acuity ranged between finger counting and 20/40 secondary to cataract. The endothelial cell count was measured preoperatively and 6 weeks after surgery. A zirconium-fluoride-based fiber was used in 23 patients and a sapphire fiber in 9 patients.
Results:
Of the patients examined after 3 months (n = 31), 90.3% (n = 28) had a visual acuity of 20/30 or better and 9.7% (n = 3), of 20/40 or 20/50. Mean endothelial cell loss at 6 weeks was 7.6% +/- 12.8 (SD). Posterior capsule rupture with vitreous loss occurred in 3 cases; 1 was attributed to laser damage to the capsule. Conversion to ultrasound phacoemulsification was required in 13 cases. Suitable fiber materials for Er:YAG laser delivery are sapphire, zirconium fluoride, silica, and germanium oxide. Toxicity of the latter is under investigation.
Conclusion:
The Er:YAG laser emulsified the lens nucleus safely and effectively. These early results include a higher than acceptable posterior capsule rupture rate and reflect the surgeon's learning curve with a new technology. Effective power delivery can be achieved with sapphire- and zirconium-fluoride-based fiber optics through a silica tip. The optimal energy delivery system has not been determined.