Corneal Refractive Therapy Design Comparison for -4 to -6 Diopter Treatment for Overnight Wear for Myopia

Inclusion Criteria: 1. Patients may be male or female, of any race, and at least 18 years old at the time of the pre-treatment examination. 2. The prospective eye(s) must have naturally occurring refractive myopia from -4.00 to -6.00 diopters sphere (spectacle plane), with up to -1.75 diopters of refractive astigmatism (spectacle plane), as determined by manifest refraction (phoropter or trial frame with a 12.5 mm vertex distance). 3. Patients must have best spectacle corrected visual acuity of at least 0.04 logMAR in each eye. 4. If the Subject wears rigid contact lenses in the prospective eye(s), lens use must cease at least four (4) weeks prior to the pre-treatment examination. The subject must have two central keratometry readings taken that are at least one week apart. The two readings shall not differ by more than 0.50 diopter in either meridian. The mires should be regular. 5. Patients must be willing and capable to return for all scheduled follow-up visits for a period of at least 6 months. Exclusion Criteria: 1. Female patients who are pregnant, breast-feeding or intend to become pregnant over the course of the study. 2. Patients with a history of any of the following medical conditions: collagen vascular disease, autoimmune disease, immunodeficiency diseases, ocular herpes zoster or simplex, endocrine disorders (including, but not limited to active thyroid disorders and diabetes), lupus, and rheumatoid arthritis. Note: The presence of diabetes (either type 1 or 2), regardless of disease duration, severity or control, shall specifically exclude patients from eligibility. 3. Patients with a history of intraocular or corneal surgery (including cataract extraction), active ophthalmic disease or abnormality (including, but not limited to, blepharitis, recurrent corneal erosion, dry eye syndrome, neovascularization \>1mm from limbus), clinically significant lens opacity, clinical evidence of trauma (including scarring). Note: This includes any Subject with open angle glaucoma, regardless of medication regimen or control. Additionally, any Subject with an intraocular greater than 21 mm Hg at baseline is specifically excluded from eligibility. 4. Patients with evidence of keratoconus, corneal irregularity, or abnormal videokeratography in either eye. 5. Patients with pupil size greater than 5.5 mm in photopic illumination as measured with infrared pupillometry, pupil detection component of computer assisted video keratography, or slit lamp reticule. 6. Patients who are participating in any other clinical trial (FDA or other).