A 50-year-old male who underwent PRK 12 years prior presented with complaints of increased blur. Examination revealed a superior-central scar located in the mid-anterior stroma. It has a lined/feathered appearance; while initially rather faint, it has increased in density over the past several years.
Feathery-looking corneal scars are a common response to infections, injuries and surgeries. This occurs when myofibroblasts—alpha smooth-muscle actin cells—are produced in excess by stromal keratocytes. Myofibroblasts are contractile and opaque cells that produce large amounts of disordered extracellular matrix (largely collagen), which creates the corneal scar appearance.
Feathery-looking corneal scars are a common response to infections, injuries and surgeries. Click image to enlarge.
These fibrotic cells are derived from keratocytes in response to growth factors from the epithelium, tears, endothelium and other stromal cells. There must be the epithelial basement membrane and/or Descemet’s basement membrane injury, which must persist for months, years or decades, in order for these growth factors to reach adequate levels in the stroma to drive fibrosis formation. Therefore, these scars may appear a significantly long time after the initial injury.
Since myofibroblast scarring often limits vision when occurring centrally, it is easy to think of it as a pathologic state. However, myofibroblasts have specific roles in wound healing, such as replacing damaged subepithelial tissue, producing extracellular matrix for tissue regeneration and contracting incisional wounds to help prevent corneal perforation. Over time, scarring produced by myofibroblasts will diminish.
Our patient was fit in a scleral lens for improvement of vision and for protection of the ocular surface. He will be routinely monitored for progression or regression. Unless the scar is imminently sight-threatening—requiring penetrating keratoplasty—no other treatment is required.
1. Wilson SE. Coordinated modulation of corneal scarring by the epithelial basement membrane and Descemet’s basement membrane. J Refr Surgery. 2019; (35)8: 506-516.
2. Wilson SE. Corneal myofibroblasts and fibrosis. Exp Eye Res. 2020; (201)9: 108272.