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Jingjing Qi, Hongli Yang, Christy Hardin, Stuart K. Gardiner, Nicholas G. Strouthidis, Brad Fortune, Claude F. Burgoyne; Spectral Domain Optical Coherence Tomography (SDOCT) Enhanced Depth Imaging (EDI) Of The Normal And Glaucomatous Non-human Primate Optic Nerve Head. Invest. Ophthalmol. Vis. Sci. 2011;52(14):166.
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To test the hypothesis that SDOCT EDI improves visibility and repeatability compared with standard SDOCT for the anterior and posterior lamina cribrosa surfaces (ALCS and PLCS).
Standard and EDI (inverted) SDOCT scans (Spectralis, Heidelberg Engineering) were obtained 30 minutes after IOP was manometrically lowered to 10 mmHg, in both eyes of 14 NHPs with unilateral early experimental glaucoma. 13 horizontal and 7 vertical radial B-scans of each SDOCT data set were delineated by one operator who was masked to the type of image acquisition. To assess image visibility, delineated ALCS and PLCS points were projected to one of 100 equal sized sectors on the neural canal opening (NCO) reference plane and the number of delineated sectors (≥2 points) was counted. Effects of image type, treatment, and region were analyzed using Poisson regression. Delineations were performed 2 additional times (2 weeks apart) on scans of 3 randomly selected NHPs to assess the reproducibility of measurements of ALCS and PLCS depth relative to the NCO.
The density of delineated points was not significantly different in sectors that could be clearly delineated by either method (the 5 sectors per scan with the highest point numbers for each method, >5 points in each,p=0.19 from gee regression). The number of delineated sectors was larger in EDI scans than standard scans, for both ALCS (22%, p=0.002) and PLCS (205%, p<0.001). This improvement in laminar visibility using EDI was significantly greater in glaucomatous eyes than control eyes (p<0.01). The increase in delineated ALCS sectors by EDI was greater in superior-inferior than temporal-nasal regions (P<0.01). The standard deviation of the mean ALCS depth per scan was significant smaller in EDI scans (p<0.0001), although pairwise differences of between repeats of the same scan were not significantly reduced (EDI:mean 0.27 um; Standard: 0.52 um;p=0.09). The maximum inter-session differences in ALCS depth was smaller in EDI (mean 14 um) than standard scans (mean 18 um). All 18 EDI repeats produced valid PLCS measures for analysis vs only 8 of 18 for standard.
The regional extent of delineated ALCS and PLCS sectors within normal and glaucomatous NHP ONHs was increased in EDI compared to standard SDOCT scans. EDI improved the reproducibility of ALCS and PLCS depth. These data suggests that evaluation of EDI lamina cribrosa imaging is warranted in human eyes.
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