Miller J, Wilson W S, Wilson C G, Uttamchandani D
Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow, UK.
Br J Ophthalmol. 2005 Sep;89(9):1147-51. doi: 10.1136/bjo.2004.060780.
To evaluate a corneal contact lens which effectively turns the anterior chamber of the eye into a cuvette, enabling the concentration of a drug to be measured using absorption spectroscopy.
A hand held contact lens incorporating optical fibres connected to a spectrograph enabled a beam of light to be directed in, across, and out of the anterior chamber. The device was used to follow the time course of drug concentration in the anterior chamber of rabbit (sedated) and humans, using topical brimonidine or fluorescein (with or without local anaesthesia). Absorbance measurements were taken for a 5-25 second period, repeated every 30 minutes. Drug concentrations were compared using absorbance peak height.
Corneal absorption starts to rise rapidly at wavelengths shorter than 315 nm. The light path within the anterior chamber is 6.9 mm (rabbit) and 5.8 mm (human), the absorbance measured also includes a corneal component. Application of fluorescein (three drops of 2% solution) in rabbit allowed detection, 60 minutes later, of a large absorbance peak at 490 nm. In the human eye, the device could not measure fluorescein (applied as in rabbit), but clearly detected brimonidine for 3 hours following topical application of 0.6 mg. Modification of the device to measure fluorescence resulted in the detection of 5.3 nM fluorescein in the ex vivo rabbit eye, an increase in sensitivity of two orders of magnitude over the absorption measurements.
This device has the potential to allow repeated measurements of drug concentrations in the anterior eye provided the drug has suitable absorption or fluorescence characteristics.
评估一种角膜接触镜，该接触镜能有效地将眼前房转变为比色皿，从而能够使用吸收光谱法测量药物浓度。
一种手持接触镜，其包含与光谱仪相连的光纤，可使光束射入、穿过并射出前房。该装置用于跟踪兔（麻醉状态）和人眼前房中药物浓度随时间的变化过程，使用的药物为局部用溴莫尼定或荧光素（有无局部麻醉）。在5至25秒的时间段内进行吸光度测量，每30分钟重复一次。使用吸光度峰值高度比较药物浓度。
在波长小于315nm时，角膜吸收开始迅速上升。前房内的光路在兔中为6.9mm，在人中为5.8mm，所测量的吸光度还包括角膜成分。在兔眼中滴入三滴2%的荧光素溶液后，60分钟后可检测到在490nm处有一个大的吸光度峰值。在人眼中，该装置无法测量荧光素（滴入方式同兔眼），但在局部应用0.6mg溴莫尼定后3小时能清晰检测到。对该装置进行改进以测量荧光，结果在离体兔眼中检测到5.3nM的荧光素，与吸收测量相比，灵敏度提高了两个数量级。
如果药物具有合适的吸收或荧光特性，该装置有可能对眼前房内的药物浓度进行重复测量。
