Axial myopia is a type of nearsightedness that happens when the eye is too long from front to back. This causes distant vision to be blurry. Axial myopia tends to start during childhood and worsens over time (as the eyes continue to grow longer). This can lead to serious eye-related conditions later in life. The aim of T10430 treatment is to stop or slow this progression during childhood and therefore, prevent more serious complications. Animal studies using drugs with a similar mechanism of action as T10430 have demonstrated positive safety results. This study aims to better understand the safety and potential effectiveness of T10430 in children with axial myopia.

The study drug, T10430, is an eye drop solution. Participants in the study will receive one of three different strengths of the T10430 eye drops or a placebo. The study will include 200 participants, aged 6 to 11 years, who have a specific type of nearsightedness.

Principal Inclusion Criteria:

1. - Informed consent signed and dated.
2. - Male or female participant between ≥ 6 and < 12 years old.
3. - Spherical equivalent refractive error (SER) of at least -1.00D and no more than -6.00D in each eye as measured by cycloplegic autorefraction.
4. - IOP < 21mmHg in each eye.
5. - Distant BCVA equal or better than 0.1 LogMAR [≤ 0.1 LogMAR (equivalent to ≥ 20/25 Snellen)] in each eye.

Principal Exclusion Criteria:

Ophthalmic exclusion criteria in AT LEAST ONE EYE (1-11):

1. Known intolerance to administration of eye drops.
2. Astigmatism > 1.50D as measured by cycloplegic autorefraction.
3. Anisometropia ≥ 1.50D as measured by cycloplegic autorefraction.
4. Current or history of amblyopia or manifest strabismus including intermittent tropia.
5. Current or history of glaucoma.
6. Current or history of significant or severe damage to the cornea.
7. Presence of anterior segment pathology (e.g. iris malformation, cataract).
8. Presence of posterior segment or retinal pathology (dystrophies).
9. History of any disease or syndrome that predisposed the participant to severe myopia (e.g., Marfan syndrome, Stickler syndrome, retinopathy of prematurity).
10. History of non-axial cause of myopia (refractive or secondary myopia).
11. History of abnormal ocular refractive anatomy (e.g., keratoconus, keratoglobus, lenticonus, spherophakia).

Systemic/non-ophthalmic exclusion criteria (12-13):

12 - Known or suspected hypersensitivity to one of the components of the IMP (T10430) or diagnostic agents used during the study (e.g., fluorescein, cycloplegic agent).

13- History of or active relevant systemic condition (e.g., connective tissue disease, allergy) incompatible with the study or likely to interfere with the study results or the participant safety according to investigator's judgment.

14- Specific exclusion criteria regarding sexually active individuals (14-15): Pregnancy for post-menarche participant (confirmed with a positive urine pregnancy test).

15- Adolescent of childbearing potential (male/female) who is sexually active and is not willing to use preventive measures.

Exclusion criteria related to general conditions (16-21):

16- Inability of participant and/or legal guardian(s) to understand the study procedures or to give informed consent.

17- Non-compliant participant and/or legal guardian(s) (e.g., not willing to attend a visit or a phone call or to complete the diary, way of life interfering with compliance).

18- Participation in this study at the same time as another clinical study. 19- Participation in this study within the 4 weeks after the end of a previous clinical study not related to myopia (or within 5 half-lives of the previously tested product if longer than 4 weeks).

20- Participant previously randomised in this study. 21- Participant being family member of the study sites or of the Laboratoires Théa company.

22- Exclusion criteria related to previous and concomitant treatments (medications/non-medicinal therapies/procedures): Participant with previous, current or anticipated prohibited listed treatment (or prohibited modification of treatment regimen).

Neither the participants nor the study doctors will know who is in which assigned group.