The Immediate Effect of Defocus Spectacles On the Choroid Thickness Using Optical Coherence Tomography on Children

Inclusion criteria

• Myopic children using Defocus Incorporated Multiple Segment Spectacle Lenses (DIMS) from the ongoing randomized clinical non-inferiority study: "Defocus Incorporated Multiple Segment (DIMS) Spectacle Lenses versus Orthokeratology lenses (OKL) for slowing myopia progression in children aged 6-12 years. A non-inferiority randomized clinical trial. The NISDO study" (ClinicalTrials.gov Identifier NCT05134935).
• Myopia at the time of inclusion in the NISDO study (inclusive): -2.00 to -4.75 D spherical component and up to -2.50 D of regular astigmatism (both eyes).
• Anisometropia at the time of inclusion in the NISDO study ≤ 1.50 D cycloplegic spherical equivalent refractive error.
• Best corrected visual acuity (inclusive) at the time of inclusion in the NISDO study: 0.8 Snellen (equivalent to ≥ 3/5 letter on the 0.8 line = 78 ETDRS letters).

Exclusion criteria

• Manifest or intermittent squint.
• Contraindications to the use of OKL comprising (not exhaustive): keratoconus, chronic allergic conjunctivitis, and keratoconjunctivitis sicca.
• Previous eye surgery.
• Chronic eye disease demanding daily use of eye drops.
• Non-compliance to eye examinations (unstable fixation or anxiety towards contact lenses).
• Previous myopia control treatment.