The present invention relates generally to the measurement of intraocular pressure, and more particularly to a non-contact, acoustic resonance determination of intraocular pressure.
Glaucoma is an eye disorder that frequently causes blindness. The internal pressure of the eye, or intraocular pressure, increases beyond the normal physiological range and, if not controlled, results in permanent damage to the retina and to the optic nerve. The disorder occurs most frequently in people over forty but may also appear as a congenital condition in children or young adults. There are several types of glaucoma and thousands of people in the U.S. alone suffer from the disease.
The bulb of the eye is composed of segments of two spheres of different sizes separated by a crystalline lens suspended from fibers connected to muscles. The chambers anterior to the lens are filled with aqueous humor and the large cavity posterior thereto is filled by semigelatinous vitreous humor. The intraocular pressure of the eye is maintained by continuous production of aqueous humor, which originates in the chamber behind the iris, flows through the pupil into the anterior chamber between the iris and the cornea, and drains into a channel leading to a network of small veins on the outside of the eye. In glaucoma, either the rate of production of aqueous humor is too high or the rate of drainage is too low causing a pathological increase in the intraocular pressure. The increased pressure is exerted, via the lens, into the vitreous humor, which, in turn, exerts an increased pressure on the retina. This pressure causes collapse of tiny blood vessels which nourish the light-sensitive cells of the retina and the fibers of the optic nerve. Deprived of the blood that provides them with essential oxygen and nutrients, the cells and nerve fibers begin to die causing permanent vision loss.
Presently, the only way to detect glaucoma early is by thorough ophthalmic examination in which a tonometer is used to measure the intraocular pressure. The tonometer requires direct physical contact with the cornea and, consequently, anesthesia is required.
Conservative management of glaucoma involves the use of medication to control the intraocular pressure. The medications involved must be taken for life and regular checkups are necessary. Glaucoma patients must monitor their intraocular pressure frequently to determine if their medication is effective and to detect potentially damaging pressure spikes. The usual practice is to visit the ophthalmologist whenever a pressure measurement is needed. This approach is expensive and discourages continued practice.
Currently, there are no simple, inexpensive pressure measurement devices available to patients for home use. Accordingly, it is an object of the present invention to provide a safe, non-contact apparatus and method for determining intraocular pressure.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.