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Abstract
Purpose
To investigate the effect of surface fluid on the ablation rate and efficacy of 213-nm solid-state laser during photorefractive keratectomy (PRK).
Methods
Twelve rabbits (24 eyes) underwent myopic PRK for the correction of 10 diopters using 213-nm solid-state laser. Photoablation was performed with removal of corneal surface fluid using the Weckcel® sponge every 5 seconds in one eye and without removal of corneal surface fluid in the control eye. The mean central corneal thickness (CCT) was evaluated preoperatively, and at 1 week, 4 weeks postoperatively.
Results
The mean CCT of group 1 (with removal of corneal surface fluid) were 361.3±13.9 µm preoperatively and 321.4±18.5 µm at 4 weeks postoperatively. The mean CCT of group 2 (without removal of surface fluid) were 358.7±8.9 µm preoperatively and 338.4±12.0 µm at 4 weeks postoperatively. The mean ablation depths were 39.8±7.4 µm in group 1 and 20.3±5.8 µm in group 2 at 4 weeks postoperatively ( p<0.05).
References
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Figure 1.
The photograph of photorefractive keratectomy using 213-nm solid-state laser in rabbit’s eye.
Figure 2.
The comparison of ablation depth at postoperative 4 weeks ( P-value<0.05, Mann-Whitney test).
Figure 3.
Schematic presentation of reflection loss. (A) Experimental model of Geoffrey et al8 (θ=90°). (B) Reflection loss on corneal surface fluid (θ<90°).
Table 1.
The comparison of central corneal thickness at preoperative, postoperative 1 week and 4 weeks
| Central corneal thickness (µm) | ||
|---|---|---|
| Group 1 (Fluid removed) | Group 2 (Not removed) | |
| Preoperative | 361.3±13.9 | 358.7±8.9 |
| Postoperative 1 week | 358.6±13.5 | 359.8±7.9 |
| Postoperative 4 weeks* | 321.4±18.5 | 338.4±12.0 |
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