Minimally invasive spectroscopic system for intraocular drug detection

A novel, minimally invasive measurement technique has been developed for the detection of drugs in the anterior chamber of the eye. Presently there is no satisfactory, real-time detection method available to the ophthalmic community. Accurate determination of drug concentrations in the eye would be of great value and assistance to researchers and manufacturers of ophthalmic drugs and ocular implants, to enable a better understanding of intraocular pharmacokinetics. At present researchers use techniques of direct sampling of the aqueous humor from laboratory animal eyes into which the drug has been introduced topically or systemically. Rabbit eyes are frequently used in this context. Sampling via paracentesis is invasive, and does not yield a continuous measurement. Our approach to addressing this measurement requirement is, in effect, to turn the eye into a cuvette and use optical absorbance spectroscopy measurements to detect drug concentrations. A novel contact lens has been designed using commercial, off-the-shelf, optical design software. The lenses have been optimized to direct light across the anterior chamber of a rabbit's eye. Practical demonstration and characterization of light propagation across the eye have been undertaken and are reported. Preliminary results of the identification of drug compounds introduced into model eyes are also reported.