Purpose: To explore the mechanism of action of topical lodoxamide and cromolyn sodium treatment in vernal keratoconjunctivitis (VKC) and to compare the efficacy of these drugs to each other.
Design: Single-investigator, masked, randomized, clinical trial.
Participants: Twenty male and 10 female patients between the ages of 6 and 19 years, who were diagnosed as having active VKC, were enrolled in this study.
Interventions: The patients were randomly divided into two equal groups (groups A and B). Group A patients received topical lodoxamide ophthalmic solution 0.1% (LOS); topical cromolyn sodium ophthalmic solution 4% (CSO) was prescribed to group B patients in a dose of two drops four times daily.
Main outcome measures: The eye symptom severity scores and clinical signs of the patients were evaluated both in the pre- and post-treatment periods. In addition to the clinical data, conjunctival impression cytologic specimens were obtained from patients both before and after treatment. Impression cytologic specimens were stained using immunohistochemical methods to detect the percentages of CD4(+), CD8(+), CD45RA(+), and CD23(+) cells. Statistical analyses were performed within and between groups.
Results: The percentages of CD4(+) and CD23(+) cells in tear samples of patients in groups A and B were significantly higher in the pretreatment stage than post-treatment stage. In the post-treatment stage, group A patients had significantly lower CD4(+) and CD23(+) cell values compared with group B patients. Patient symptom scores and clinical signs were at a significantly lower level after treatment with either LOS or CSO in both groups A and B compared with their pretreatment values. Moreover, group A patients had significantly lower symptom scores and clinical signs than group B patients in the post-treatment stage.
Conclusions: Clinical superiority of LOS over CSO may be linked to its greater effect on the CD4(+) cells, because CD4(+) cells plays a pivotal role in the pathogenesis of VKC.