What should be tested for if there is no identified underlying condition in anterior uveitis?

In cases of anterior uveitis where no identifiable underlying condition is found, testing for HLA-B27 status is particularly important. This is because anterior uveitis is often associated with systemic conditions, and one of the key associations is with HLA-B27-related disorders, such as ankylosing spondylitis, reactive arthritis, and other spondyloarthropathies. A positive HLA-B27 can indicate a higher likelihood of these conditions, which can lead to appropriate management and treatment strategies for the patient.

While other tests like visual acuity are crucial for assessing the immediate impact of uveitis on vision, they do not provide information regarding underlying systemic issues. Similarly, thyroid function tests and complete blood count can be important in other contexts but are not specifically indicated for the evaluation of idiopathic anterior uveitis. The HLA-B27 test directly correlates with the potential systemic causes that may be contributing to the uveitis, making it the most relevant test in this scenario.