Analysis of risk factors associated with secondary open-angle glaucoma in Posner-Schlossman syndrome: A retrospective case-control study

Abstract

Background: Posner-Schlossman syndrome (PSS) is a relatively rare cause of chronic secondary open-angle glaucoma (OAG), but the exact cause is unknown. This study aimed to determine potential risk factors for OAG secondary to PSS and to provide a basis for early intervention in the development of PSS.

Methods: This was a retrospective case-control study. Nine cases diagnosed with PSS and seven cases diagnosed with OAG secondary to PSS were selected and their aqueous humor assays at the first occurrence of PSS were collected. Clinical characteristics including age, sex, disease duration, eye laterality, baseline visual acuity, maximum IOP, corneal endothelial cell density, visual field, retinal nerve fiber layer thickness, cup-to-disk ratio, keratic precipitates, anterior chamber inflammation, and aqueous humor cytokine assay results were compared between the two groups.

Results: The cytomegalovirus (CMV) positivity was 55.60% in patients with PSS and 100% in patients with OAG secondary to PSS. Corneal endothelial cell density was lower in patients with CMV-positive PSS (p = 0.0116). Concentrations of basic fibroblast growth factor (bFGF), interleukin (IL)-6, and vascular cell adhesion molecule (VCAM) in patients with PSS and IL-8, IL-6, and VCAM in patients with OAG secondary to PSS were higher than standard reference values; and IL-8 concentration was significantly higher in patients with OAG secondary to PSS (p = 0.0229). There were significant positive correlations between IL-8 and IL-6, IL-6 and VCAM (p = 0.0304, p = 0.0172) and a significant negative correlation between bFGF and vascular endothelial growth factor (VEGF) (p = 0.0497). Simultaneous increase of IL-8 and IL-6 concentration levels could be used as a cytokine indicator to predict secondary OAG in patients with PSS (p = 0.0095).

Conclusion: Simultaneous increase of IL-8 and IL-6 concentrations may be an important cause of accelerated secondary OAG in patients with PSS, with IL-8 playing a more critical role. IL-8 and IL-6 may be more reliable cytokine markers for predicting secondary OAG in PSS, However, the high possibility of secondary OAG in patients with CMV-positive PSS should not be ignored. Regulation of IL-8 and IL-6 levels may be a new strategy of preventing OAG secondary to PSS.

Keywords: Posner-Schlossman syndrome; anterior uveitis; cytomegalovirus (CMV); interleukin; intraocular pressure; open-angle glaucoma.

FIGURE 1

Distribution of cytokine concentrations for PSS and PSS + OAG. The PSS + OAG group had significantly higher cytokine IL-8 concentration levels (145.10 [0.00-337.20]pg/ml) than the PSS group (12.20 [4.70-58.50]pg/ml). The concentration levels of IL-6, IL-10, VEGF, bFGF, and VCAM did not differ significantly between the groups. *p<0.05. bFGF, basic fibroblast growth factor; IL, interleukin; OAG, open angle glaucoma; PSS, Posner-Schlossman syndrome; VCAM, vascular cell adhesion molecule; VEGF, vascular endothelial growth factor.

FIGURE 2

Correlations between the cytokines in the two groups. IL-8 and IL-6 (ρ = 0.5412, p = 0.0304) and IL-6 and VCAM (ρ = 0.5853, p = 0.0172) were significantly positively correlated. bFGF and VEGF (ρ = –0.4978, p = 0.0497) were significantly negatively correlated. bFGF, basic fibroblast growth factor; IL, interleukin; VCAM, vascular cell adhesion molecule; VEGF, vascular endothelial growth factor.

FIGURE 3

Accuracy of correlated cytokines in predicting OAG secondary to PSS. IL-8 together with IL-6 (p = 0.0095) had higher accuracy in predicting OAG secondary to PSS than IL-8 alone (p = 0.0229). IL-6 with VCAM (p = 0.7110) and bFGF with VEGF (p = 0.1248) had no predictive value. bFGF, basic fibroblast growth factor; IL, interleukin; OAG, open angle glaucoma; PSS, Posner-Schlossman syndrome; VCAM, vascular cell adhesion molecule; VEGF, vascular endothelial growth factor.