Fluid accumulation in the flap interface (Interface fluid syndrome) as a complication after corneal refractive surgery

Relevance. One of the rare complications after refractive surgery, accompanied by formation of a superficial flap or an intrastromal corneal pocket, is the syndrome of fluid accumulation in the flap interface/ intrastromal space – Interface Fluid Syndrome (IFS). There is no mention of IFS in the Russian literature. Purpose. To summarize current understanding of pathogenic mechanisms and risk factors for the development of IFS, identify problems in the prevention of IFS. Material and methods. PubMed and eLibrary web platforms were used to search relevant studies using the following keywords: interface fluid, interface corneal edema, interlamellar flap edema, interface fluid syndrome, IFS. 71 sources were analyzed in the period up to 2023. Results. The fluid accumulation in the interface after LASIC was first described by Lyle W.A. and Jin G.J. in 1999. Subsequently, studies were published that linked the development of this syndrome with a deficiency of corneal endothelial cells and an increased level of intraocular pressure (IOP). The syndrome can manifest itself both immediately after refractive surgery against the background of concomitant ocular pathology, and after other eye surgery. Terms of IFS onset varies from a few days to several years after refractive surgery. IOP levels in IFS should be monitored using non-aplanation methods. A case of IFS development in a patient with Chandler syndrome has been described for the first time. Conclusion. IFS is a rare complication after refractive surgery. Prevention of this condition is based on a thorough examination of patients both before refractive surgery and when planning other interventions. Treatment of the syndrome is aimed at normalizing IOP and performing corneal endothelial surgery. An increase in the incidence of IFS should be expected in the future due to the high number of refractive procedures. Key words: interface fluid, interface corneal edema, interlamellar flap edema, interface fluid syndrome, IFS