Keratoconus May Indicate Underlying Systemic Connective Tissue Pathology

Keratoconus may be associated with connective tissue hyperlaxity, indicating that the disorder may be more than just a local disturbance of corneal structure, according to research published in Contact Lens and Anterior Eye. These connective tissue hyperlaxity manifestations involve the lower extremities, spine, and abdomen, according to the report.

“The pathophysiology of keratoconus is multifactorial, including a genetic predisposition, enzymatic corneal degradation, alteration in collagen fibril arrangement and environmental influences,” the investigators explain. “Several systemic conditions involving connective tissue hyperlaxity and collagen disturbances have been shown to be related to keratoconus…”

Researchers examined the charts of 940,763 adolescents and young adults (mean age, 17.55 years; 40% girls) and determined the prevalence of ligament injuries, habitual orthopedic deformities, and umbilical or inguinal hernia in individuals with and without keratoconus. Study participants underwent ophthalmic evaluation, corneal tomography, and medical history assessment, and investigators examined associations between systemic connective tissue disorders and keratoconus using both univariate and multivariate analyses.

A total of 0.16% of participants had keratoconus (n=1529), and these individuals were more likely to be boys, have taller height, and heavier weight, according to the report. Patients with this corneal ectasia were significantly more likely to have scoliosis (odds ratio [OR], 1.88; 95% CI, 1.45–2.43; P <.0001), genu varum or valgus (OR, 2.75; 95% CI, 1.48–5.13; P =.0015), pes planus (OR, 1.97; 95% CI, 1.62–2.38; P <.0001), or hernia (OR, 2.18; 95% CI, 1.47–3.24; P =.0001) compared with participants without keratoconus. The team did not note any associations between keratoconus and joint injuries.

“These findings suggest the existence of a systemic underlying connective tissue pathology rather than a local one as a cause of keratoconus,” according to the study authors.

Study limitations include a retrospective nature, a coding system that does not allow for disease severity to be recorded, and an inability to perform a genetic analysis.