Inclusion Criteria:  Myopic children aged 6 to 12 years. Myopia of the 6 to 8-year-olds: -1.00 to -4.75 D spherical component and up to -2.50 D of regular astigmatism. Myopia of the 9 to 12-year-olds: -2.00 to -4.75 D spherical component and up to -2.50 D of regular astigmatism. Anisometropia < 1,5 D cycloplegic spherical equivalent refractive error. Best corrected visual acuity: Age 6 to 8 (inclusive) years: 0.8 Snellen (equivalent to ≥ 3/5 letter on the 0.8 line = 78 ETDRS letters). Age 9 to 12 years: 1.0 Snellen (equivalent to ≥ 3/5 letter on the 1.0 line = 83 ETDRS letters)  Exclusion Criteria:  Manifest or latent squint. Contraindications to the use of OKL comprising keratoconus, chronic allergic conjunctivitis and keratoconjunctivitis sicca. Previous eye surgery. Chronic eye disease demanding daily use of eye drops. Non-compliance to eye examinations