The association between keratoconus and systemic manifestations of connective tissue hyperlaxity

Purpose: To evaluate the correlation between keratoconus and systemic manifestations of tissue hyperlaxity in the general population. Methods: In this population based cross-sectional study 940,763 medical records of Israeli adolescents and young adults in military service were reviewed. Demographic and medical data were extracted. The prevalence of ligament injuries, habitual orthopedic deformities and umbilical/inguinal hernia was evaluated in cases with and without keratoconus. The association was tested using uni- and multivariant analyses. Results: Overall 938,411 adolescents and adults were included. Mean age was 17.55 ± 1.50 years, and 40.70% were female. Keratoconus was documented in 1,529 cases, with a prevalence of 0.16%. Compared to the general population, patients with keratoconus were significantly more likely to be diagnosed with genu varum/valgus (OR = 2.75, CI 1.48–5.13, p = 0.0015), pes planus (OR = 1.97, 95% CI: 1.62–2.38, p < 0.0001), scoliosis (OR = 1.88, 95% CI: 1.45–2.43, p < 0.0001) and umbilical/inguinal hernias (OR = 2.18, 95% CI: 1.47–3.24, p = 0.0001). On multivariate analysis the results remained significant (p < 0.05 for all). Joint injuries (ankle sprains, shoulder dislocation and injury to knee ligaments and menisci) were not significantly related to keratoconus (p > 0.05 for all). Conclusions: In this large cohort of adolescents and young adults, an association was found between keratoconus and connective tissue hyperlaxity manifestations involving the knees, feet, spine and abdomen. These findings suggest that keratoconus might be a manifestation of a generalized connective tissue disorder, rather than just a local ocular phenomenon.