The aim of the present study is to gain more information about retinal functional parameters in myopic children in Europe. For this purpose, a prospective case-control study in children aged between 8 and 13 years, as this is the usual age of myopia onset, will be conducted. Forty myopic children will be age- and sex-matched to non-myopic controls. Retinal oxygen extraction will be used as the main outcome parameter, as data from animal and human studies point towards an involvement of hypoxia in the disease process. In addition, other parameters probably linked to myopia will be investigated, such as retinal and choroidal blood flow as well as choroidal and retinal vessel density and anatomical structures such as choroidal and central retinal thickness. Also, questionnaires about lifestyle factors will be completed.

Inclusion criteria for children with myopia:

• Children aged between 8 and 13 years (inclusive)
• Signed informed consent of child and legal guardian
• Normal ophthalmic findings except myopia
• Cycloplegic spherical equivalent (SE) refraction ≤ -1.0dpt in both eyes
• Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant

Inclusion criteria for healthy age- and sex-matched controls:

• Children aged between 8 and 13 years (inclusive)
• Signed informed consent of child and legal guardian
• Normal ophthalmic findings
• Cycloplegic spherical equivalent (SE) refraction between +0.5dpt and -0.5dpt
• Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant

Exclusion Criteria:

• Intake of stimulating beverages containing xanthine derivatives (tea, coffee, cola-like drinks) 12 hours before the study day
• Previous eye abnormalities such as cataract, keratopathy, strabismus, amblyopia, ocular inflammation, trauma, or surgery
• History of any disease or syndrome associated with severe myopia such as Marfan syndrome, Stickler syndrome, or retinopathy of prematurity
• Non-axial cause of myopia
• BCVA less than 20/25
• Intraocular pressure ≥ 21mmHg
• Astigmatism ≤ -1.0dpt
• Anisometropia ≥ 2dpt
• Not able to read letters for visual acuity testing

40 children with myopia and 40 healthy age- and sex-matched controls