Intense pulsed light alleviates keratoconus by improving the local corneal microenvironment

Keratoconus (KC) is a corneal ectasia with a complex etiology, and its pathogenesis remains incompletely understood. Research indicates that the development of KC is closely linked to inflammation and local oxidative stress (OS) triggered by alterations in the microenvironment of the ocular surface. Intense pulsed light (IPL) has been shown to enhance the ocular surface microenvironment, decrease inflammatory cytokines, and mitigate oxidative stress associated with KC progression. We hypothesize that IPL may impede the advancement of KC through several mechanisms. IPL treatment could lead to a decrease in inflammatory mediators (such as IL-1, IL-17, IL-6, etc.) in the eyelid margin and ocular surface, as well as a reduction in matrix metalloproteinases (MMPs) levels in tears, while elevating tissue inhibitor of metalloproteinases (TIMPs) levels, thereby slowing down extracellular matrix (ECM) degradation. Moreover, IPL stimulates fibroblasts to upregulate the expression of type I and type III procollagen mRNA and enhance ECM synthesis. Additionally, IPL regulates tear reactive oxygen species (ROS) levels, elevating tissue superoxide dismutase (SOD) levels through light modulation, maintaining the balance between oxidation and antioxidation, and lessening OS-induced damage. Lastly, IPL diminishes the urge of patients to rub their eyes by alleviating the itching sensation. In conclusion, IPL holds promise as a potential therapeutic approach for managing KC.