Mydriasis as a Secondary Effect in Patients With HLA‐B27–Associated Uveitis

ABSTRACT Acute anterior uveitis (AAU) is the most common form of uveitis, and approximately 90% of AAU cases are associated with human leukocyte antigen (HLA)‐B27. This association explains the characteristic findings of iris inflammation, redness, visual impairment, and photosensitivity due to pupil dilation from stimulation of the iris dilator muscles, linking HLA‐B27–associated uveitis to mydriasis. Mydriasis occurs for physiological or pathophysiological reasons, such as trauma, disease, or drug effects. Retrospective studies indicate that isolated mydriasis is noted in 6% of HLA‐B27–positive patients. In contrast, 19% patients with herpetic acute uveitis exhibit mydriasis. A comprehensive search of PubMed, Scopus, Web of Science, and Google Scholar was performed from 1 November 2009 to 30 November 2024, using terms such as “HLA‐B27,” “uveitis,” “mydriasis,” and “pupil dilation.” Studies published in English within the past decade that specifically addressed mydriasis in HLA‐B27–associated uveitis were included. HLA‐B27‐associated uveitis disturbs the parasympathetic pathway with elevated levels of cytokines (interleukin‐2, interferon‐γ, and interleukin‐12), thereby directing inflammation of the iris and simultaneously influencing its muscular control and sympathetic tone, leading to mydriasis. Mydriatics are used to control HLA‐B27‐associated AAU along with eye spasms and swelling of the anterior eye by dilating the pupils to prevent the development of posterior synechiae. However, the prolonged use of mydriatics has several consequences. The present review synthesizes current evidence regarding the prevalence, underlying mechanisms, and clinical management of mydriasis in HLA‐B27‐associated uveitis, thereby providing novel insights for improved diagnosis and therapeutic strategies.