Relationship between lamina cribrosa displacement and trans-laminar pressure difference in papilledema.

Abstract

The purpose of this study was to describe morphological changes in lamina cribrosa (LC), prelaminar tissue thickness (PTT) and Bruch's membrane opening (BMO) in eyes affected by papilledema and correlate them with trans-LC-pressure difference (TLCD). This was a prospective study, including twelve eyes newly diagnosed of papilledema. Eyes underwent scanning with Spectralis-OCT with enhanced depth imaging to compare BMO, anterior LC surface position (LC depth-LCD-) and PTT before and after oedema resolution. Correlation analysis between these parameters and TLCD was performed. TLCD inversely correlated with LCD at baseline and directly with LC reversal movement after lowering cerebrospinal fluid pressure (CSFP) (ρSpearman: -0.739, p=0.006; ρSpearman: 0.844, p=0.001 respectively). At onset, RNFL thickening and BMO were significantly larger in eyes with TLCD > -9.2mmHg (group 2) compared with TLCD < -9.2mmHg (group 1) [p=0.007, p=0.041 respectively]. A significant RNFL and BMO shrinking were observed, but they were significantly larger in group 2. The magnitude of LC displacement following oedema resolution was significantly larger and in the opposite direction in group 2 vs group 1 (-68.7μm vs 19.5μm, p=0.016). TLCD correlated with RNFL thickening at baseline (ρSpearman: 0.667, p=0.018) and with RNFL thinning at last visit (ρSpearman: 0.673, p=0.017). TLCD correlated with mean deviation (MD) (ρSpearman: 0.712, p=0.014) and visual field index (VFI) (ρSpearman: -0.657, p=0.028) at onset. MD and VFI were worse in group 2. LC position was significantly related to TLCD in papilledema. Eyes with higher TCLD showed significantly larger backward LC movement, BMO shrinking and RNFL thinning after lowering CSFP compared with eyes with lower TLCD, where LC movement occurred in the opposite direction.