McQuaid Rebecca, Mrochen Michael, Vohnsen Brian
From the Advanced Optical Imaging Group (McQuaid, Vohnsen), School of Physics, University College Dublin, Dublin, Ireland, and IROC Science AG (Mrochen), Zurich, Switzerland.
From the Advanced Optical Imaging Group (McQuaid, Vohnsen), School of Physics, University College Dublin, Dublin, Ireland, and IROC Science AG (Mrochen), Zurich, Switzerland.
J Cataract Refract Surg. 2016 Mar;42(3):462-8. doi: 10.1016/j.jcrs.2015.09.032.
To determine the diffusion of riboflavin from intrastromal channels through the effective diffusion coefficients compared with traditional axial diffusion with epithelium on or off.
Advanced Optical Imaging Laboratory, University College Dublin, and Wellington Eye Clinic, Sandyford, Dublin, Ireland.
Experimental study.
The rate of diffusion in whole-mounted porcine eyes was monitored for a 30 minutes using an optical setup with a charge-coupled device camera and a bandpass filter (central wavelength 550 nm and 40 nm bandpass) to image the fluorescence under ultraviolet illumination (365 nm wavelength). For comparison, an isotropic corneal stroma with an annular channel was modeled numerically for different diffusion constants and boundary conditions.
Numerical and experimental results were compared, allowing determination of the effective diffusion coefficient for each case. Experimental results for 6 different riboflavin solutions were in all cases found to be higher than for the common crosslinking (CXL) riboflavin protocol, where the diffusion constant is D0 = 6.5 × 10(-5) mm(2)/sec. For the intrastromal channel, 2 isotonic solutions containing riboflavin 0.1% correlated with a diffusion constant of 5D0 = 32.5 × 10(-5) mm(2)/sec. Hypotonic solutions and transepithelium had a higher diffusion coefficient approaching 10D0 = 65.0 × 10(-5) mm(2)/sec, which is an order-of-magnitude increase compared with the typical diffusion coefficient found in standard CXL.
In this study, riboflavin had a faster stromal diffusion when injected into a corneal channel than when applied as drops to the anterior corneal surface. Further numerical modeling might allow optimization of the channel structure for any specific choice of riboflavin.
通过有效扩散系数确定核黄素在基质内通道中的扩散情况，并与上皮存在或不存在时的传统轴向扩散进行比较。
都柏林大学学院高级光学成像实验室以及爱尔兰都柏林桑迪福德的惠灵顿眼科诊所。
实验研究。
使用配备电荷耦合器件相机和带通滤波器（中心波长550纳米，带通40纳米）的光学装置，在紫外线照射（波长365纳米）下对全层猪眼的扩散速率进行30分钟监测，以成像荧光。为作比较，针对不同的扩散常数和边界条件，对具有环形通道的各向同性角膜基质进行了数值模拟。
对数值和实验结果进行比较，从而确定每种情况下的有效扩散系数。在所有情况下，6种不同核黄素溶液的实验结果均高于普通交联（CXL）核黄素方案，后者的扩散常数为D0 = 6.5×10⁻⁵ 平方毫米/秒。对于基质内通道，两种含0.1%核黄素的等渗溶液的扩散常数为5D0 = 32.5×10⁻⁵ 平方毫米/秒。低渗溶液和经上皮给药时扩散系数更高，接近10D0 = 65.0×10⁻⁵ 平方毫米/秒，与标准CXL中发现的典型扩散系数相比增加了一个数量级。
在本研究中，将核黄素注入角膜通道时，其在基质中的扩散比滴注到角膜前表面时更快。进一步的数值模拟可能有助于针对任何特定的核黄素选择优化通道结构。
