Purchase this article with an account.
Tiffany E. Choe, Carla J. Abbott, Juan Reynaud, Claude F. Burgoyne, Brad Fortune; Comparison Of Spectral Domain Optical Coherence Tomography (SDOCT) Imaging Modalities To Identify Deeper Structures Within The Rat Optic Nerve Head (ONH). Invest. Ophthalmol. Vis. Sci. 2012;53(14):2820.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare SDOCT imaging modalities, 870 versus 1050 nm sources with and without enhanced depth imaging (EDI), for in vivo visualization of deeper structures within the rat ONH.
Eight adult male Brown-Norway (pigmented) and two Sprague Dawley (albino) rats were imaged in both eyes by SDOCT (Spectralis, Heidelberg Engineering, GmbH) under general anesthesia (ketamine:xylazine:acepromazine, 55:5:1 mg/kg IM). SDOCT scans consisted of 290 horizontal B-scans with 768 A-scans/B-scan covering a 15°x15° area centered on the ONH. Automatic real-time tracking (ART) software was used to average 25 sweeps per B-scan and to register the scan locations across the four imaging modalities: 870 and 1050 nm sources, each with and without EDI. Scans with the same dimensions but a vertical raster orientation were also obtained from one pigmented and two albino rats. Using custom 3D visualization and delineation software, SDOCT volumes were scored by a masked observer (1:poor to 4:good) for the detail of each of the following deep ONH and peripapillary structures: Bruch’s membrane opening (BMO), choroid, scleral surfaces, scleral sling, optic nerve (ON), and lamina cribrosa. The average score for each eye was grouped by imaging modality; groups were compared by ANOVA with eyes matched and post hoc tests corrected for multiple comparisons. The ONC and BMO were delineated within the 1050-EDI volumes of all pigmented rats to determine dimensions.
The average scores for the 870, 870-EDI, 1050, 1050-EDI volumes, respectively, were 2.52 ± 0.28, 2.81 ± 0.22, 2.95 ± 0.27, and 3.12 ±0.20 (p<0.0001, ANOVA; R²=0.45, p<0.0001, post test for linear trend). The 1050-EDI scores were higher than both 870 and 870-EDI, and the 870 EDI scores were higher than 870 without EDI (each p<0.001). Vertical sections (real or interpolated) provided the best definition of the ON, possibly because the angle of the ON became increasingly oblique superiorly with distance behind the BMO plane, averaging 70.4 ± 4.6 deg at 150 to 200 µm posterior to BMO (i.e. within the sclera). At the same distance from BMO, the ON cross-sectional area was 0.036 ± 0.011 mm². BMO area was 0.069 ± 0.009 mm². Greater detail of deeper structures was generally apparent in the albino rats.
The longer wavelength SDOCT imaging source (1050 nm) and EDI modality provided subjectively better visualization of the deep ONH and peripapillary structures in the rat. BMO and ON cross sectional areas as well as the obliquity of the ON deep within the scleral canal observed here in vivo are consistent with, though slightly smaller than previous histomorphometric estimates of these dimensions.
This PDF is available to Subscribers Only