Change in excimer laser systems prior to completion of study

The purpose of this study is to assess whether there is a significant difference in visual outcomes or corneal haze after surface ablation for moderate and high myopia in active duty service members treated with PRK, Mitomycin-C (MMC) PRK and LASEK.

Inclusion Criteria:

1. Informed consent.
2. Normal, healthy, active duty adults age 21 years or older. The lower age limit of 21 years is intended to ensure documentation of refractive stability.
3. Manifest refractive spherical equivalent of greater than -4.00 diopters (D) up to -10.00 D.
4. Best spectacle corrected visual acuity of 20/20 or better in both eyes.
5. Demonstrated refractive stability, confirmed by clinical records. Neither the spherical nor the cylindrical portion of the refraction may have changed more than 0.50D during the 12-month period immediately preceding the baseline examination, as confirmed by clinical records.
6. Both eyes must fall in the same refraction group and there must be less than 1 D difference between eyes.
7. Soft contact lens users must have removed their lenses at least 2 weeks before baseline measurements. Hard contact lens users (PMMA or rigid gas permeable lenses) must have removed their lenses at least 4 weeks prior to baseline measurements and have 2 central keratometry readings and 2 manifest refractions taken at least 1 week apart that do not differ by more than 0.50 D in either meridian.
8. Access to transportation to meet the follow-up requirements.
9. Available for evaluation during the 1-year follow-up period.
10. Consent of the subject's command to participate in the study.

Exclusion Criteria:

1. Female subjects who are pregnant, breast-feeding or intend to become pregnant during the study. Women of childbearing age will take a urine pregnancy test before starting this study.
2. Residual, recurrent or active ocular diseases or corneal abnormalities in either eye such as keratoconus, iritis, uveitis, keratoconjunctivitis sicca, vernal conjunctivitis, lagophthalmos, corneal scarring, glaucoma, previous steroid responder, occludable chamber angles, visually significant cataracts.
3. Medical condition(s), which, in the judgment of the investigator, may impair healing, including but not limited to: collagen vascular disease, autoimmune disease, immunodeficiency diseases, and ocular herpes zoster or simplex.
4. Concurrent topical or systemic medications that may impair healing, including corticosteroids, antimetabolites, isotretinoin (Accutane), amiodarone hydrochloride (Cordarone) and/or sumatripin (Imitrex).
5. Any physical or mental impairment that would preclude participation in any of the examinations.
6. Prior refractive or ocular surgery.