Lamina Cribrosa Position and Superior Visual Field Loss in Glaucoma

Abstract

 

Purpose

 

To compare the position of the lamina cribrosa (LC) in glaucomatous eyes with superior hemifield visual field defects (VFD) with its position in normal eyes, to see if posterior LC displacement occurs in association with VFD.

 

Methods

 

Normal subjects and glaucoma patients with VFD limited to the superior hemifield were recruited. All participants had a complete ophthalmologic examination including standard automated perimetry and retinal nerve fiber layer (RNFL) thickness measurement using optical coherence tomography (OCT). Serial horizontal enhanced depth imaging (EDI) OCT B-scans of the optic nerve head were obtained from each participant (interval between scans = ~30 μm). After delineating the anterior LC surface, mean and maximum LC depths (reference plane, Bruch’s membrane edges) were measured in 11 equally spaced horizontal B-scans, excluding the LC insertion area under Bruch’s membrane and the scleral rim (Fig A and B). Mean and maximum LC depths in each of the 11 B-scans were compared between the 2 groups.

 

Results

 

57 normal eyes (57 subjects; mean age = 56±18 years) and 35 glaucomatous eyes with only superior VFD (35 patients; mean age = 59±17 years; VF mean deviation = -5.9±4.0 dB) were included. The RNFL was significantly thinner in the glaucomatous eyes in both the inferior (59 vs. 95 µm; p<0.01) and in the superior retina (81 vs. 98 µm; p<0.01) compared to the normal eyes. Both mean and maximum LC depths were significantly greater in the glaucomatous eyes in all 11 scans (all p<0.01; Fig C and D). Posterior LC displacement in the glaucomatous eyes appeared to be similar between the superior and inferior LC.

 

Conclusions

 

We found generalized posterior displacement of the entire central and mid-peripheral LC in the glaucomatous eyes with VFD limited to the superior hemifield, suggesting that detectable LC displacement occurs early in human glaucoma prior to the development of VFD. Studies are needed to elucidate the causal and temporal relationships of peripheral LC deformation with glaucomatous VFD.

 

 

(A) White dots = Bruch’s membrane edges; black dots = anterior laminar insertion points; maximum lamina cribrosa (LC) depth = black double arrow; mean LC depth = (area S / length D). (B) The circle indicates the LC. (C and D) Mean and maximum LC depth profiles in the normal and the glaucoma groups.

 

Keywords: 577 lamina cribrosa • 550 imaging/image analysis: clinical • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)