The goal of this clinical trial is to learn whether children and young adults with well-controlled juvenile idiopathic arthritis (JIA)-associated uveitis or chronic anterior uveitis can safely take adalimumab (or biosimilar) injections less often while maintaining control of their disease.

The main question it aims to answer is: can adalimumab/biosimilar injections be given less frequently without uveitis (eye inflammation) or arthritis (joint inflammation) returning?

Researchers will compare adalimumab/biosimilar injection schedules of every 2 weeks, 4 weeks, 8 weeks, and 12 weeks to determine how injection frequency affects disease control.

Participants will:

• Take adalimumab/biosimilar injections every 2, 4, 8, or 12 weeks.
• Attend study visits every 6 weeks over 24 weeks, with an additional follow-up visit at 48 weeks for checkups, tests, and questionnaires.
• Keep a diary of how often they take adalimumab/biosimilar and other drugs they take for their uveitis/arthritis.

Inclusion Criteria:

• Stated willingness to comply with all study procedures and availability for the duration of the study period
• History of juvenile idiopathic arthritis (JIA) or chronic anterior uveitis (CAU), diagnosed prior to 16 years of age (patient may be older than 16 at time of enrollment)
• ≥2 years of age (per FDA approval for use in children with polyarticular JIA)
• Weight must be ≥15kg
• Formal diagnosis of JIA-associated uveitis or CAU with no other suspected etiology
• ≥24 consecutive months of controlled ocular inflammation (≤0.5+ anterior chamber cell, ≤0.5+ vitreous haze, and no active retinal/choroidal lesions in either eye)
• ≥24 consecutive months of controlled arthritis verified by a pediatric rheumatologist if defined as JIA-associated uveitis
• ≥24 consecutive months of treatment with adalimumab or biosimilar of adalimumab
• ≥180 days on a stable dose of adalimumab or biosimilar of adalimumab; dose must be no greater than 20mg (if weight <30kg), or 40mg (if weight ≥30kg), injected every two weeks
• If on biosimilar of adalimumab, ≥90 days on the biosimilar
• Ability to continue to obtain commercial supply of adalimumab or biosimilar
• If on a conventional disease-modifying anti-rheumatic drug (cDMARD) (injectable or oral methotrexate, mycophenolate mofetil, azathioprine, or leflunomide), dose must be ≤25 mg weekly for methotrexate, ≤3 g daily for mycophenolate mofetil, ≤250 mg daily for azathioprine, or ≤20 mg daily for leflunomide; dose and route of administration must be stable for ≥90 days
• Willingness to limit consumption of alcohol during the study period
• Agreement to avoid live attenuated vaccinations
• Agreement to use highly effective contraception or abstinence for ≥28 days prior to screening and throughout the study period (for males and females of reproductive age)
• Suitable, in the opinion of the Investigator, to continue treatment with adalimumab/biosimilar per regional labeling

Exclusion Criteria:

• History of acute anterior uveitis characterized by redness and symptoms, including but not limited to floaters, pain, and light sensitivity
• Intraocular surgery in the past 90 days or planned surgery in the next 24 weeks
• Severe cataract or opacity preventing view to the posterior pole in both eyes
• Chronic hypotony (<5mmHg for ≥90 days) in either eye
• Treatment with oral corticosteroids or intraocular corticosteroid injection within the last 24 weeks
• Use of topical corticosteroid eye drops within the last 90 days
• Use of nonsteroidal anti-inflammatory drug (NSAID) eye drops within the last 90 days
• Pregnancy or lactation (a pregnancy test will be conducted at baseline and follow-up visits for females post-menarche)
• Presence of intraretinal or subretinal fluid in either eye
• Prior safety or tolerability issues with adalimumab
• History of cancer, active tuberculosis, or hepatitis B
• Other medical condition expected to dictate treatment course during the study
• Any of the following laboratory test results on their most recent tests within the past 90 days prior to screening/enrollment: leukocyte count <2500, platelet count ≤75000, hemoglobin<9.0, aspartate transaminase (AST) or alanine transaminase (ALT) ≥ 2 times the upper limit of normal range, creatinine ≥1.5