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Refractive changes after excimer laser phototherapeutic keratectomy
M Dogru1, C Katakami, A Yamanaka
1Eye Clinic, Kobe Kaisei Hospital, Kobe, Japan.
Journal of Cataract and Refractive Surgery
|May 30, 2001
Summary
Phototherapeutic keratectomy (PTK) improves vision for superficial corneal opacities but often induces hyperopia. Shallow ablation, transition zone settings, and masking agents can significantly reduce this induced hyperopia.
Area of Science:
- Ophthalmology
- Corneal Surgery
- Refractive Errors
Background:
- Superficial corneal opacities can impair vision.
- Excimer laser phototherapeutic keratectomy (PTK) is used to treat these opacities.
Purpose of the Study:
- To evaluate visual and refractive changes after PTK for superficial corneal opacities.
Main Methods:
- 112 eyes of 80 patients underwent PTK using the Nidek EC-5000 excimer laser.
- Ophthalmic examinations, including visual acuity, refraction, keratometry, corneal topography, and pachymetry, were performed pre- and post-procedure.
- Factors influencing hyperopic shift, such as ablation depth and masking agents, were assessed.
Main Results:
- Best corrected visual acuity (BCVA) improved by at least one line in 89.2% of eyes.
- A mean hyperopic shift of 3.42 diopters was observed at 12 months post-PTK.
- The hyperopic shift peaked at 1 month and stabilized by 12 months.
Conclusions:
- PTK is effective for superficial corneal opacities but frequently induces hyperopia.
- Minimizing ablation depth, utilizing transition zone settings, and employing masking agents can significantly reduce the degree of induced hyperopia.