Inclusion Criteria:
* Be of legal age or, if under legal age have written consent of their parent or guardian to participate.
* Sign written Informed Consent (and the California Bill of Rights, if applicable).
* Ages 6-35 (inclusive) and able to understand and assent to participation
* Current wearers of Euclid Emerald (Oprifocon A) Orthokeratology lenses, which at initiation of fitting, had
* Need of optical correction for myopia, from -1.00 to -5.00 Diopters (D).
* Refractive astigmatism of less than -1.50 D.
* Have a minimum Best Spectacle Corrected Visual Acuity (BSCVA) of 20/40 or better in each eye.
* Have acceptable or optimal fit with study lenses (once fitting has been completed) and be willing to wear these lenses as directed for the duration of the study.
* On examination, have ocular findings considered to be within normal limits, including:
* No evidence of active infection involving the conjunctiva, lids or adnexa.
* No evidence of structural abnormalities of the lid, conjunctiva or adnexal tissue considered significant by the investigator to include minimum levels (Grade 2 or less) of tarsal-conjunctival abnormalities
* Clear corneas with no evidence of edema, staining, opacities, corneal neovascularization greater than a trace amount (i.e. All vessels extending less than 1.5 mm from the limbus); all as observed on slit lamp examination.
* No iritis.
* No herpes keratitis (recurrent or otherwise) or other active ocular disease that would contraindicate lens wear or lessen attainability of VA sought in this study (20/40 or better).
* No evidence of dry eye or meibomian gland dysfunction
* Normal binocularity (no amblyopia or strabismus, and no anisometropia of greater than 2.00D)
* Be willing and able to follow instructions and attend the schedule of follow-up visits.
Exclusion Criteria:
* Does not meet the any of the above inclusion criteria
* Not able or willing to provide informed consent and assent
* Requires concurrent ocular medication
* Eye injury or surgery within twelve weeks immediately prior to enrollment
* Pre-existing ocular condition that would preclude contact lens fitting
* Currently enrolled in an ophthalmic clinical trial
* Pregnant or lactating or expect to become pregnant during the trial
* Evidence of systemic or ocular abnormality, infection or disease likely to affect successful wear of contact lenses or use of their accessory solutions.
* Allergy or sensitivity to any product used in this trial
* Any systemic disease including autoimmune disease, immunocompromising diseases, connective tissue disease, clinically significant atopic diseases, insulin dependent diabetes, use of medications including corticosteroids and antimetabolites that may affect the eye or be exaggerated by contact lenses.
* Strabismus/amblyopia
* Habitual uncorrected anisometropia ≥ 2.00D
* Subjects who have undergone corneal refractive surgery
* Subjects with severe corneal irregularity contraindicating lens wear
* Inability to wear contact lenses, or an unacceptable contact lens fit
* Poor or unacceptable fit with any study lens
* Employees, staff or family members of personnel at the site
