Diagnostic capabilities of corneal confocal microscopy in monitoring local conservative therapy to prevent early recurrence of chronic anterior uveitis associated with spondyloarthritis

Relevance Associated anterior uveitis (PU) is characterized by a high relapse rate - from 47.5 to 90.9%. Exacerbations last from 5-7 weeks to 3 months, with a frequency of 0.6-3.3 times per year. Relapses can be accompanied by a more severe course, involvement of the posterior segment of the eye, complications and a significant decrease in visual acuity. Langerhans cells (LC) - atypical macrophages that activate innate and adaptive immunity in anterior uveitis - play a key role in the inflammatory response. In a healthy cornea, Langerhans cells, represented by resident dendritic cells, are found in small quantities, while the number of LC increases from the central to the peripheral zone of the cornea. During inflammation, the number of LC increases, especially in the central zone of the cornea [1-4]. Objective To study the capabilities of corneal confocal microscopy in assessing inflammation and the effectiveness of therapy in recurrent PU associated with spondyloarthritis (SpA). Material and methods Laser confocal microscopy of the cornea (HRT III with Rostock Cornea Modul, Heidelberg Engineering, Germany), image processing in Liner Calculate software. Clinical observation of 35 people was carried out over the period from 2022 to 2024. The average age of patients was 38.1 ± 9.82 years. Results In patients with exacerbation of chronic PU, corneal confocal microscopy (CCM) showed an increase in the number and density of Langerhans cells - an average of 13.75 cells with a total length of processes of 30.19 mm / mm². Against the background of conservative therapy (instillation of glucocorticosteroids (GCS), non-steroidal anti-inflammatory drugs (NSAIDs), mydriatics, parabulbar injections of GCS), the number of CL decreased to 4.5 cells with a process length of 1.19 mm/mm². In 5 patients, despite the absence of complaints and clinical signs, active forms of CL remained on the CMR (on average 6.7 cells, process length 2.39 mm/mm²), which indicated ongoing inflammation and the risk of early relapse when therapy was discontinued. Conservative therapy was continued under the control of the CMR. However, it should be taken into account that systemic therapy (NSAIDs, GCS, disease-modifying antirheumatic drugs, genetically engineered biological drugs) prescribed by rheumatologists can also affect the course of inflammation and the frequency of PU relapses [5]. Conclusion The number and density of CLs detected by CMR are an important criterion for deciding whether to continue or discontinue local therapy in patients with PU in the absence of obvious clinical signs. However, the frequency of PU exacerbations also depends on the systemic therapy prescribed by rheumatologists, which requires further study. Keywords: corneal confocal microscopy; corneal nerve fibers; Langerhans cells; anterior uveitis; HLA-B27