This systematic review aimed to determine the comorbid dry eye (DE) and allergic conjunctivitis (AC) prevalence. We searched PubMed and EMBASE for articles published until 22 March 2022, combining the terms "(dry eye OR keratoconjunctivitis sicca) AND allergic conjunctivitis." Study-specific estimates (DE and AC incidence rates among patients with AC and DE, respectively) were combined using the one-group meta-analysis in a random-effects model. The initial search yielded 700 studies. Five articles reporting AC incidence among individuals with DE and six articles reporting DE incidence among individuals with AC were included in the qualitative synthesis. In these nine articles, the total sample size was 7254 patients. The DE incidence among individuals with AC was 0.9-97.5%; the AC incidence among individuals with DE was 6.2-38.0%. One-group meta-analysis using a random-effects model showed that 47.2% (95% confidence interval: 0.165-0.779; 320/1932 cases) of patients with AC had comorbid DE and 17.8% (95% confidence interval: 0.120-0.236; 793/4855 cases) of patients with DE had comorbid AC, as defined by each article. Complimentary screening and treatment for patients with DE and AC may improve long-term outcomes and prevent chronic ocular damage in highly susceptible populations.
Keywords: allergic conjunctivitis; comorbidity rate; complementary treatment; dry eye; meta-analysis; perennial allergic conjunctivitis; seasonal allergic conjunctivitis; systematic review.