Prevalence and Risk Factors Associated with Keratoconjunctivitis Sicca in People Living with Human T-Leukemia Virus Type 1: A Systematic Review and Meta-Analysis.

To estimate the global prevalence of keratoconjunctivitis sicca (KCS) among Human T‑cell lymphotropic virus type 1 (HTLV‑1)-infected individuals and to evaluate diagnostic methods and research gaps within ocular immunology. A systematic review and meta‑analysis were performed per PRISMA. We searched PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane CENTRAL, SciELO, LILACS, DOAJ, OpenGrey, and CAPES through December 2023. Eligible studies were cross‑sectional or cohort investigations reporting KCS prevalence in confirmed HTLV‑1-seropositive adults (ELISA or Western blot). Two independent reviewers screened 289 records, with discrepancies resolved by a third. Eight studies met the inclusion criteria. The random‑effects pooled prevalence of KCS in HTLV‑1 infection was 34.6% (95% CI: 19.8%-51.0%; I  = 97.2%). Patients with HTLV‑1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) exhibited a higher prevalence (prevalence ratio [PR]: 2.01; 95% CI: 1.73-2.31). Diagnostic approaches in six studies employed Rose Bengal staining, Schirmer I test, and tear film breakup time. Approximately one in three HTLV‑1-infected patients develop KCS, with elevated risk in those with HAM/TSP. Persistent heterogeneity-driven by diagnostic variability, geographic factors, and demographic differences-underscores the need for standardized criteria, inclusion of diverse populations, and further research on proviral load, gender, and ethnicity to inform ocular practice, including immunology.