Repeatability of in vivo 3D lamina cribrosa microarchitecture using adaptive optics spectral domain optical coherence tomography

Abstract

We demonstrate the repeatability of lamina cribrosa (LC) microarchitecture for in vivo 3D optical coherence tomography (OCT) scans of healthy, glaucoma suspects, and glaucomatous eyes. Eyes underwent two scans using a prototype adaptive optics spectral domain OCT (AO-SDOCT) device from which LC microarchitecture was semi-automatically segmented. LC segmentations were used to quantify pore and beam structure through several global microarchitecture parameters. Repeatability of LC microarchitecture was assessed qualitatively and quantitatively by calculating parameter imprecision. For all but one parameters (pore volume) measurement imprecision was <4.7% of the mean value, indicating good measurement reproducibility. Imprecision ranged between 27.3% and 54.5% of the population standard deviation for each parameter, while there was not a significant effect on imprecision due to disease status, indicating utility in testing for LC structural trends.

Keywords: (100.2000) Digital image processing; (110.4500) Optical coherence tomography; (170.1610) Clinical applications; (170.4470) Ophthalmology; (330.4460) Ophthalmic optics and devices.

Fig. 1

6° scan of the lamina cribrosa taken as the confocal scanning laser ophthalmoscopy (CSLO) frame pans horizontally across the volume. AO-SDOCT (right of each pane) shows the tissue cross-section corresponding to the center of the CSLO frame, which is then used to register and reconstruct the volume.

Fig. 2

3D LC (a) and C-scan (b,e) visualization (a) is segmented in C-mode slices (c,f) permitting the quantification of structural parameters such as beam thickness where thicker beams are shown in yellow and thinner beams are purple (d,g).

Fig. 3

Repeated C-mode slices of the same eye with pore segmentation (a, b) and skeleton presentation of the beams (d, e). Segmentation is overlaid on C-mode from similar location and compared with yellow color representing full agreement (c, f).

Fig. 4

Pore volumes for repeat scans visualized in 3D (left) and histogram of cross-sectional pore area (right) sampled in C-mode slices shows qualitative agreement between scans. Differences in visualizable lamina manifest as differences in pore count for excluded pores.

Fig. 5

C-mode slices taken from repeated scans of a glaucomatous eye are colored by beam orientation (left) which translates to a similar distribution shape for beam orientation angle between scans (right). Orientation analysis includes all C-mode slices in the LC.

Fig. 6

Bland-Altman plots of pore diameter separated by distribution percentile. Lines show the 95% confidence intervals for paired differences. Measurement spread is fairly consistent through all pore sizes.