Background <p>Cataract is the leading cause of blindness worldwide, with corticosteroid treatment being a known risk factor. The long-term impact of childhood asthma and, particularly, inhaled corticosteroid (ICS) use in adulthood on cataract development remains unclear.</p> Methods <p>This register-based study investigated the prevalence and risk of cataract in Danish adults diagnosed with childhood asthma who, between 1950 and 1979, spent four months at an asthma care facility in Kongsberg, Norway. Follow-up was conducted in 2021 using Danish national health registries (2006–2018). These individuals were compared to an age- and sex-matched control group with no history of obstructive airway disease. Participants were stratified by ICS treatment duration and daily dose. Conditional logistic regression was used to assess associations.</p> Results <p>The study included 1394 adults with childhood asthma and 1394 controls (mean age 63&#xa0;years; 43% female). Cataract prevalence was 6.1% in the childhood asthma cohort versus 4.3% in controls (<i>p</i> = 0.03). Compared to controls, individuals with childhood asthma had increased odds of cataract (OR 1.47, 95% CI 1.04–2.08, <i>p</i> = 0.03). Among those treated with ICS, the odds were higher (OR 1.75, 95% CI 1.19–2.57, <i>p</i> &lt; 0.01), with the risk increasing in proportion to ICS dose and treatment duration. No significant difference in cataract risk was found between individuals with childhood asthma who did not receive ICS and controls (OR 1.12, 95% CI 0.69–1.79, <i>p</i> = 0.65).</p> Conclusions <p>Childhood asthma diagnosis alone was not associated with increased cataract risk. However, among those treated with ICS in adulthood, there was a significantly elevated risk, which increased with higher doses and longer treatment durations.</p>