FIELD OF THE INVENTION

The present application pertains to laser-assisted eye surgery using a liquid optical interface and, more particularly, to systems and methods for monitoring and reacting to insufficient liquid within the interface.

BACKGROUND

A cataract is formed by opacification of the crystalline lens or its envelope—the lens capsule—of the eye. The cataract obstructs passage of light through the lens. A cataract can vary in degree from slight to complete opacity. Early in the development of an age-related cataract, the power of the lens may be increased, causing near-sightedness (myopia). Gradual yellowing and opacification of the lens may reduce the perception of blue colors as those wavelengths are absorbed and scattered within the crystalline lens. Cataract formation typically progresses slowly resulting in progressive vision loss. If left untreated, cataracts may cause blindness.

A common cataract treatment involves replacing the opaque crystalline lens with an artificial intraocular lens (IOL). Every year, an estimated 15 million cataract surgeries are performed worldwide. Traditionally, cataract surgery has been typically performed using a technique called phacoemulsification in which an ultrasonic tip with associated irrigation and aspiration ports is used to sculpt the relatively hard nucleus of the lens to facilitate removal through an opening made in the anterior lens capsule. Access to the lens nucleus can be provided by performing an anterior capsulotomy in which a small round hole is formed in the anterior side of the lens capsule using a surgical. Access to the lens nucleus can also be provided by performing a manual continuous curvilinear capsulorhexis (CCC) procedure. After removal of the lens nucleus, a synthetic foldable intraocular lens (IOL) can be inserted into the remaining lens capsule of the eye.

One of the most technically challenging and critical steps in the cataract extraction procedure is providing access to the lens nucleus for removal of the cataract by phacoemulsification. The desired outcome is to provide a smooth continuous circular opening through which phacoemulsification of the nucleus can be performed safely and easily, and also through which an intraocular lens may be easily inserted. Because of the criticality of this step, some surgeons prefer a surgical laser beam over manual tools like microkeratomes and forceps since the laser beam can be focused precisely on extremely small amounts of eye tissue, thereby enhancing the accuracy and reliability of the capsulotomy procedure.

Several commercial laser-assisted eye surgery systems are available to facilitate cataract removal and astigmatism correction. The CATALYS Precision Laser System from Abbott Medical Optics is indicated for anterior capsulotomy, phacofragmentation, and the creation of single plane and multi-plane arc cuts/incisions in the cornea to correct astigmatism. The CATALYS System uses a two-piece liquid-filled interface that docks with the patient's eye with the liquid providing a transmission medium for the laser, thus avoiding distortion of the eye from contact with an applanation lens. The liquid provides a clear optical path for real-time video, OCT imaging, and laser treatment. Aspects of the CATALYS System are disclosed in U.S. Pat. Nos. 8,394,084, 8,500,724, 8,425,497, U.S. Patent Publication 2014/0163534, U.S. patent application Ser. No. 14/256,307, filed Apr. 18, 2014, and U.S. Patent Publication No. 2014/0343541, filed Apr. 17, 2014, the contents of all of which are incorporated herein by reference as if fully set forth. Other systems for laser cataract surgery are the LenSx Laser from Alcon Laboratories, Inc., the LENSAR Laser System from LENSAR, Inc., and the VICTUS Femtosecond Laser Platform from TECHNOLAS Perfect Vision GmbH a Bausch+Lomb Company.

The interstitial layer of fluid has a strong influence on the delivery of a high fidelity laser spot in the correct location. One drawback with current systems that use liquid-filled optical interfaces is loss of liquid. Most docking interfaces rely on suction to hold the interface to the eye, and sometimes to hold separate pieces of the interface together. If during a laser procedure the interface shifts so that the liquid-filled chamber comes in fluid communication with the suction in any of these couplings, the level of liquid in the interface may be reduced to be replaced with air which has a different index of refraction and would affect the laser optics. If this happens during laser treatment, it is important to shut off delivery of the laser energy before any mistreatment, or even injury, can occur.

Accordingly, there is a need for systems that detect loss of liquid in the optical interface.

SUMMARY

Improved laser eye surgery systems, and related methods, are provided. The laser eye surgery systems use a laser to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. In a preferred embodiment, a laser eye surgery system includes a laser cutting subsystem to produce a laser pulse treatment beam to incise tissue within the eye. A liquid transmissive media is used between a patient interface lens and the eye to avoid imparting undesirable forces to the patient's eye. The present application provides a number of solutions for monitoring the liquid level within the patient interface.

One particular embodiment of a liquid monitor includes one or more sensors positioned within the patient interface and in communication with the liquid therein. The sensors may be conductive pads which conduct current therebetween through the liquid until the liquid level drops too low. Alternatively, a light source may be shone down onto the liquid within the patient interface and light refracted through the liquid monitored for changes in the liquid level. Still further, a matched pair of acoustic emitter and sensor may be integrated into the patient interface which produce different signals when the liquid levels are high and low. Another solution is to incorporate an extremely small diameter orifice in the side of the liquid chamber and pull a very low vacuum on the orifice. If the liquid is covering the orifice, surface tension will prevent aspiration of the fluid, but when the liquid level drops air can be pulled through the orifice which is detected by an external sensor in the vacuum line. Finally, a gas flow meter may be installed within a vacuum supply circuit for a suction ring on the patient interface. The gas flow meter detects major suction losses as well as slow leaks by utilizing a sensor of high sensitivity.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

