**Compassionate Use Study of Epi-ON Corneal Collagen Crosslinking for Ectatic Corneal Diseases in Down Syndrome** This study is about corneal crosslinking (CXL), an experimental treatment to help strengthen the cornea (clear front part of the eye) using riboflavin (Vitamin B2) drops and ultraviolet (UVA) light. The cornea can become thin and change shape, making vision blurry. This study aims to see if CXL can stop or slow down these changes. Participants must be at least 8 years old, have Down syndrome, and certain eye conditions. **Key Points:** - **Duration & Visits:** The study requires up to 7 visits over 6 months. - **Treatment:** Participants will receive CXL, which involves 20 minutes of UVA light exposure. - **Eligibility:** Must have a specific corneal condition and provide consent. Participants should not have had a corneal transplant, other major eye diseases, or be pregnant. They must follow instructions and attend all visits. This study is not FDA-approved, meaning it is still being tested for safety and effectiveness.