Visualization of the lamina cribrosa using enhanced depth imaging spectral-domain optical coherence tomography

To investigate whether the enhanced depth imaging technique (EDI) may improve the visualization of the lamina cribrosa using spectral-domain optical coherence tomography (SD-OCT).

Prospective observational case series.

Images of the optic nerve were obtained in 10 normal subjects, 7 glaucoma suspects, and 18 glaucoma patients by positioning an SD-OCT in the usual fashion, as well as close enough to the eye to obtain an inverted representation of the fundus (EDI). In addition to these single line scans, approximately 65 sections were obtained within a 10 × 15-degree rectangle covering the optic nerve head using EDI. The "depth of signal" was measured as the distance from the optic cup surface and the point where the signal ended in both single line scan images.

Compared to the image obtained with the SD-OCT used in the usual fashion, images obtained with EDI provided larger depth of signal (728.04 ± 124.20 vs 368.79 ± 75.15 μm, P < .001) below the optic cup surface and better image contrast from the deep optic nerve; this facilitated the discrimination of the lamina cribrosa. In the en face image, the lamina cribrosa was visualized as a highly reflective plate containing multiple pores that corresponded with the color fundus photographs.

Using EDI SD-OCT, the full-thickness lamina cribrosa was clearly visualized in all eyes examined. This technique should facilitate the investigation on the lamina cribrosa in glaucoma, and may provide additional insight into the pathogenesis of glaucomatous optic neuropathy.