This study will assess the optimal performance characteristics of optical defocus on transient changes in axial length with Kubota Glass, using a randomized, double-masked, 5-treatment, 5-period crossover design with contralateral eye control.

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).
• Be between age 8-24 (inclusive) and able to understand and assent to participation.
• Have a spherical component of spectacle prescription between -1.00 and -5.00 diopters (D) (inclusive) in each eye.
• Have a refractive astigmatism of less than or equal to -1.00 D in each eye.
• Have axial length between 23.00 and 25.99 millimeters (mm) in each eye.
• Best Spectacle Corrected Visual Acuity (BSCVA) of 20/25 or better in each eye.
• Be willing and able to follow instructions and attend the schedule of follow-up visits.

Exclusion Criteria:

• Unable or unwilling to provide informed consent and assent.
• Eye injury or surgery within twelve weeks immediately prior to enrollment.
• Currently enrolled in an ophthalmic clinical trial.
• Pregnant or lactating or expect to become pregnant during the trial (by self-report).
• Evidence of systemic or ocular abnormality, infection or disease.
• Use of medications that may affect the eye (including, but not limited to, corticosteroids and antimetabolites).
• Anisometropia ≥ 2.00.
• Subjects who have undergone corneal refractive surgery.
• Use atropine or other anticholinergic drug within the past month.
• Employees or immediate family members of employees of study sites or sponsor.