Acute corneal hydrops in keratoconus - new perspectives.

PURPOSE: To summarize the current concepts and recent literature regarding the epidemiology, pathogenesis, imaging modalities, and treatment of acute hydrops in keratoconus.
DESIGN: Perspective.
METHODS: Review and synthesis of selected literature, with interpretation and perspective.
RESULTS: Acute corneal hydrops is an incompletely understood complication of keratoconus, characterized by marked corneal edema caused by a break in Descemet membrane, allowing aqueous to enter the corneal stroma and epithelium. Although usually self-limiting, with clinical signs of edema typically resolving after 3 months, it often leaves a vision-impairing scar, necessitating and expediting the need for corneal transplantation. Studies have identified risk factors for developing acute hydrops. Modern imaging modalities such as ultrasound biomicroscopy, anterior segment optical coherence tomography, and in vivo confocal microscopy have enlightened us to the microstructural changes that take place during acute hydrops, the factors that influence its duration, and sequelae. Newer treatment regimens have seen a reduction in the duration of corneal edema during acute hydrops, and have improved the survival of corneal grafts after transplantation for resolved hydrops.
CONCLUSIONS: Effective management of acute corneal hydrops in keratoconus is based on recognizing and addressing the risk factors, treating the acute event effectively and promptly to reduce the duration of edema and its complications, and, ultimately, successful corneal transplantation with acceptable long-term graft survival rates. Improved in vivo imaging of the cornea during acute hydrops has led to an enhanced understanding of the pathogenesis and ultrastructural changes of the condition, and in turn has resulted in improved management of the disease.