Diffuse lamellar keratitis
Reviewed by Inderpaul Sian

This study group reviewed cytokine- and chemokine-mediated mechanisms of diffuse lamellar keratitis (DLK) after lamellar corneal surgical procedures. DLK can occur early or late (months to decades) after all lamellar corneal surgeries, including laser in situ keratomileusis, small incision lenticule extraction, anterior lamellar keratoplasty and Descemet’s stripping automated endothelial keratoplasty. It is most commonly triggered by epithelial injury during or after lamellar surgery, which leads to the release of interleukin (IL)-1α, IL-1β, and tumour necrosis factor (TNF)-α from the epithelium and into the stroma. These chemokines directly attract inflammatory cells into the cornea from the limbal blood vessels and also bind to receptors on keratocytes and corneal fibroblasts where myriad chemokines are upregulated that also chemotactically attract monocytes, macrophages, granulocytes, lymphocytes, and other bone marrow-derived cells into the corneal stroma. Other factors that can trigger DLK include retained blood in the interface, endotoxins and other toxins, and excessive keratocyte necrosis caused by femtosecond lasers. The mainstay of treatment is topical corticosteroids, but severe cases may also be treated with flap lift irrigation and systemic corticosteroids. The group concluded that DLK can occur early or late after any lamellar corneal surgical procedure and is most commonly triggered by epithelial-stromal-bone marrow-derived cellular interactions mediated by corneal cytokines and chemokines.

Pathophysiology and treatment of diffuse lamellar keratitis.
Wilson SE, de Oliveira RC.
JOURNAL OF REFRACTIVE SURGERY
2020;36(2):124-30.