Chapter 11 - Inflammation in Keratoconus

Abstract

Keratoconus (KC) is a corneal ectatic condition characterized by focal structural changes resulting in biomechanical weakening of the cornea leading to irregular astigmatism, corneal scarring, and decrease in visual acuity. Dysregulation in extracellular matrix (ECM) remodeling in the cornea results in KC. ECM remodeling both in the cornea and elsewhere in the body is known to be regulated by a variety of molecular factors. Variations in these regulating molecular factors may contribute to ECM-associated disease such as ectasia and fibrosis. Despite KC being historically and commonly defined as a noninflammatory corneal ectatic disease, there is growing evidence to suggest otherwise. Studies over the last two decades have demonstrated the relationship between KC and a variety of dysregulated inflammatory factors, both local (ocular surface, cornea) and systemic, in KC patients. The risk of KC is also increased in those with immunological conditions, such as atopy and allergy. Furthermore, management of inflammation and/or associated immune conditions have shown cessation or stabilization of disease progression. Decrease in ocular surface inflammation post collagen cross-linking has also been observed. These findings strongly implicate inflammatory factors in the pathogenesis of KC. Hence, it is now apparent that inflammatory factors play a role in keratoconus inflammation-mediated focal ectasia in the human cornea. Strategies that include monitoring molecular inflammatory factors and use of immune/inflammatory modulators would be clinically beneficial to improving the prognosis in KC.