Glaucoma is characterized by a progressive loss of retinal ganglion cells, a characteristic optic neuropathy and patterns of visual field loss in the more advanced stages. Even though glaucoma can be caused by many different risk factors, the increased intraocular pressure (IOP) is identified as the main risk factor of glaucoma. As a result, doctors often require continuous monitoring of the IOP for effective treatment of glaucoma. The change of IOP causes a change in the radius of curvature of the cornea as the aforementioned mechanical change can be used as an indication of the IOP. Current methods to measure the radius of corneal curvature require expensive electrical components and connections. Even though most patients get tested once a year during their eye-exams, patients at risk of increase IOP require continuous monitoring of the change of IOP. The existing methods of measuring the radius of curvature require electrical connections and radio frequency components, raising safety concerns and making them uncomfortable and expensive. Additionally, the high cost of these devices does not allow long term monitoring of radius of curvature changes. Even though some existing contact lenses are able to measure the IOP through a microfluidic channel, these contact lenses lack the required lifetime, which is greater than 24 hours, to be used as a practical device. The reason that the existing contact lenses lack the required lifetime is the permeability of the Polydimethylsiloxane (PDMS) that causes a gas leak. Another problem with the existing contact lenses is the surface energy of the sensing liquid is not taken into consideration. As a result, the high surface energy of the sensing liquid causes high capillary pressure drop that causes non-linear sensor behavior.
It is an objective of the present invention is to provide a contact lens with a microfluidic channel to monitor radius of curvature of the cornea with high sensitivity, high linearity, and with long lifetime. The present invention includes a microfluidic channel that converts the changes in the radius of corneal curvature into gas/liquid interface movement inside the microfluidic channel. Then the movement of gas/liquid interface can be optically detected by utilizing an external imaging system that includes components such as a camera, a lens, a microscope and a light source. As a result, the present invention provides a low cost contact lens that can be daily worn by the patients over the years of treatment. The present invention also greatly improves the effectiveness of glaucoma treatment which typically is for the lifetime of the patient.