Abstract
Purpose: :
To determine whether optic disc size affected the correlations between retinal nerve fiber layer (RNFL) thickness measured with scanning laser polarimetry (SLP) and visual field (VF) sensitivity in glaucoma.
Methods: :
We examined 106 patients with glaucoma using SLP (GDx VCC) and Humphrey VF analyzer. Correlations between RNFL thickness and VF mean sensitivity (MS) were estimated by Spearman’s rank correlation coefficient and multivariate medium regression analysis (pseudo R2), adjusting for age, sex, axial length and glaucoma type. Disc size was derived using the vertical and horizontal disc diameters shown on GDx VCC printout, after correcting for axial length.
Results: :
The correlation between RNFL thickness and MS (in decibel scale) was stronger in the group with small disc size (rs = 0.56, P < 0.001, pseudo R2 = 31%) than in the group with large disc size (rs = 0.28, P = 0.042, pseudo R2 = 15%). With Bonferroni correction, the structure-function correlation was significant in the superotemporal (rs = 0.67), superonasal (rs = 0.51), inferonasal (rs = 0.54), and inferotemporal (rs = 0.42) sectors in the small disc group (all P <0.005), while it was significant only in the superotemporal (rs = 0.47) and inferotemporal (rs = 0.56) sectors in the large disc group (both P <0.001). The results were similar when MS was expressed as unlogged 1/Lambert scale.
Conclusions: :
Compared to eyes with larger optic disc, eyes with a smaller optic disc have stronger global and sectoral structure-function correlations.
Keywords: imaging/image analysis: clinical • visual fields • optic disc