Drug detection in the living eye using a novel, minimally invasive optoelectronic system

We report the successful construction of an ocular spectrometer, with a hand-held sensor head, connected to the rest of the instrument via two optical fibers. When this sensor head is placed on the surface of the cornea, it effectively turns the anterior chamber of the eye into a cuvette, enabling absorption spectroscopy and measurements derived therefrom to be undertaken. Real-time spectroscopic measurements have clearly demonstrated the presence of a topically applied drug - brimonidine - in the cornea and anterior chamber of in vivo human and rabbit eyes. To our knowledge, this is the first ever demonstration of real-time, ocular drug detection in the living eye using absorption spectroscopy. The instrument developed was used to conduct an initial study on the time course and dose-dependent kinetics of brimonidine levels in the rabbit anterior eye. A small modification to one of the sensor heads also enabled fluorescence measurements to be taken. We propose that this system will enable ocular pharmacologists to measure drug concentrations in the anterior eye by absorption and/or fluorescence spectroscopy.