Differential permeability rate and percent clearing of glucose in different regions in rabbit sclera

Abstract

Imaging of biological tissues with optical coherence tomography (OCT) poses a great interest for its capability to noninvasively outline subsurface microstructures within tissues. However, a major limitation for many optical imaging techniques is inadequate depth penetration of light in turbid media, which is bounded to just a few millimeters. There have been several attempts to improve light penetration depth in biological tissues, including application of different tissue optical clearing methods. In this study, an aqueous solution of glucose (40%) is added to rabbit sclera in vitro, where depth-resolved permeability coefficients and optical clearing are calculated with OCT. The permeability rate in regions in the upper 80- to 100-microm region is found to be different from that of regions in the deeper 100-microm region: (6.01+/-0.37)x10(-6) cmsec and (2.84+/-0.68)x10(-5) cmsec, respectively. A difference in percent clearing is also noted. Optical clearing of the upper region is about 10% and increased to 17 to 22% in the one beneath. These results demonstrate the capability of OCT-based methods to not only measure the diffusion rate and optical clearing of a tissue, but also its ability of functional differentiation between layers of epithelial tissues.

The characteristic time of glucose diffusion measured for muscle tissue at optical clearing

“…Optical clearing of tissues induces tissue dehydration and refractive index matching by agent inclusion in the interstitial space of the tissue [3]. By placing an OCA in the interstitial space of the tissue and reducing the water content, the refractive index difference between the scatterers and the interstitial presented with results for the diffusion time for some OCAs such as dimethyl sulfoxide [17], glucose [18][19][20], mannitol [18], sucrose [21], glycerol [22], lactose and fructose [21] in different biological tissues and phantoms. A study that was recently published provided results for glucose diffusion permeability in normal and cancerous oesophageal tissues [23].…”

Quantification of glucose and glycerol diffusion in myocardium

“…Most of them are overviewed in Refs. 3, 4, 11-17 and recent ones present optical clearing of tissues such as skin, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] sclera, [33][34][35] and skeletal muscle. [36][37][38][39][40][41] We have found that only in two papers optical clearing of heart tissues were investigated.…”

Optical coherence tomography for vulnerability assessment of sandstone

“…It is therefore difficult to quantitatively compare directly the MIP derived permeability (in units of area) and the OCT measured hydraulic conductivity (in units of speed). In OCT applications to biological tissues, fluid flow rate is often quoted as a permeability coefficient [20,21], which is not the same as the intrinsic permeability described above.…”

“…OCT produces noninvasive and nondestructive depth resolved quantification of hydraulic conductivity in sandstones and other porous materials to determine vulnerability of the material to weathering. This is analogous to OCT monitoring of the permeability coefficient of aqueous glucose solution in biological tissues [20,21].…”

“…The effect of this is to reduce scattering within the sample and decrease the pixel intensity values of the image. Optical clearing is a well-known technique in OCT imaging of biological tissues [19,20]. OCT produces noninvasive and nondestructive depth resolved quantification of hydraulic conductivity in sandstones and other porous materials to determine vulnerability of the material to weathering.…”