Ultraviolet solid-state laser (213-nm) photorefractive keratectomy. In vivo study.
BACKGROUND
The pulsed ultraviolet 213-nm solid-state laser has been demonstrated as an alternative to the gas argon-fluoride 193-nm excimer laser for photorefractive keratectomy (PRK). The authors studied the clinical course and histopathologic changes occurring in rabbit corneas after PRK with a 213-nm solid-state laser.


METHODS
The 213-nm output of neodymium:YAG frequency-quintupled laser was used to create 5-mm optical zone ablations in seven pigmented rabbit corneas. The radiant exposure was 250 mJ/cm2 delivered through a computer-controlled scanning delivery system with a spot size of 0.5 mm. The target ablation was 4.0 diopters with an estimated ablation depth of 40 microns. A clinical estimate of corneal epithelial healing and stromal haze was made at intervals over the 3-month study period. Animals were killed immediately after ablation, or at 10 days, 1 month, or 3 months after ablation. Corneal tissue was preserved for light microscopy and transmission electron microscopy at each study interval.


RESULTS
All corneas re-epithelialized within 10 days postoperatively. Anterior stromal haze was clinically visible at 3 days, increased until approximately 1 month, and then gradually decreased over the succeeding 2 months. Residual subepithelial haze was visible at 3 months. Results of histopathologic study documented normal epithelium healing over time; the basement membrane retained its regular thickness and hemidesmosomes were abundant at 3 months. The anterior stroma had an increased number of fibroblasts at 10 days, many of which remained until 1 month. A mild, transient, cellular reaction occurred throughout the thickness of the stroma and the endothelium.


CONCLUSIONS
Using the 213-nm ultraviolet solid-state laser with a scanning delivery system, PRK shows a similar clinical course and histopathologic findings to the 193-nm excimer PRK study in rabbits. It is a clinically viable procedure for refractive surgery and requires further human clinical trails to determine its efficacy.
Ren
Q
Q
Department of Ophthalmology, University of California at Irvine 92715.
Simon
G
G
Legeais
J M
JM
Parel
J M
JM
Culbertson
W
W
Shen
J
J
Takesue
Y
Y
Savoldelli
M
M
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure; D003319:Corneal Stroma / Q000648:ultrastructure; D004848:Epithelium / Q000601:surgery / Q000648:ultrastructure; D005347:Fibroblasts / Q000648:ultrastructure; D005500:Follow-Up Studies; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D011817:Rabbits; D012030:Refractive Errors / Q000473:pathology; D054140:Refractive Surgical Procedures; D014466:Ultraviolet Rays; D014945:Wound Healing