Surgery – Instruments – Light application
Reexamination Certificate
1999-08-05
2002-09-24
Peffley, Michael (Department: 3739)
Surgery
Instruments
Light application
C606S015000, C607S092000
Reexamination Certificate
active
06454763
ABSTRACT:
1. FIELD OF THE INVENTION
The present invention relates to the field of laser surgical instruments for use in optical surgery. More particularly, the present invention relates to a device that uses laser light to ablate ocular tissue, while at the same time minimizing potential damage to the eye during surgery by providing a structure which is capable of trapping laser light used in the surgical procedure.
2. TECHNICAL BACKGROUND
The eye has an anterior chamber and a posterior chamber which are separated by a normally transparent lens. The lens is a clear tissue located behind the pupil. The lens works with the transparent cornea, which covers the eye's surface, to focus light on the retina at the back of the eye. The lens of the eye is clear at birth, but is one of the first parts of the body to show the effects of aging. If the lens becomes cloudy, light cannot pass to the retina properly and vision is blurred and decreased. This clouding of the lens is known as a cataract.
As the lens becomes increasingly cloudy, light rays are prevented from passing through the lens and focusing on the retina. Early lens changes may not disturb vision. But as the lens continues to change, several specific symptoms may develop including blurred vision, sensitivity to light and glare, increased nearsightedness, or distorted images.
Cataracts are the leading cause of vision loss among adults age 55 and older. The most common cause of cataracts is aging. However, cataracts can affect all ages because they can result from injury, heredity, chronic eye disease, or system-wide diseases such as diabetes.
Sometimes, the cataract stops developing in its early stages, and vision is only slightly decreased. But if it continues to develop, vision is impaired, and treatment is necessary. Surgery to remove the cataract is the only effective treatment.
Cataract surgery has been practiced over a long period of time. In the earliest known technique the cataract was displaced to lie in the vitreous cavity in the back of the eye. Other ancient techniques included breaking up the cataract with a needle to facilitate absorption by the body, and removing the lens from the eye by applying pressure. The displacement or removal of the lens enabled the patient to see better. However, vision was still blurred because the patient lacked a lens to focus light.
In modern cataract surgery the cataract is extracted from the eye. In most cases the lens is replaced with a foldable lens implant inserted into the capsular bag. The lens unfolds within the bag during the surgical procedure in order to replace the natural lens taken out. With the insertion of the replacement lens, the patient is able to focus light as well as benefitting from the removal of the cataract. Thus, vision can be effectively restored to a normal state.
Cataract surgery has become quite common in the United States and other nations. The increasing incidents of cataract surgery has been due in part to the development of improved surgical instruments and techniques. Some of the improved instruments include the operating microscope with coaxial illumination. In addition, surgical instruments have been developed which provide simultaneous irrigation and aspiration for use in closed eye microsurgical systems. It will be appreciated that fluid pressure must be maintained within narrow limits in order to avoid damage to the eye. Therefore, devices which provide both aspiration and irrigation have been an important advance in ocular surgery.
Instrumentation of this type can operate through a small incision in the eye. Typically the incision is approximately 3-4 mm in length. Using this type of instrumentation cataract surgery is performed in which the cortical material of the lens is aspirated. However, the hard nucleus of the lens must be fragmented first and then aspirated.
One device which fragments the cataract is called a phacoemulsifier. This type of device uses an ultrasonically driven vibrating needle as a means of breaking up the cataract. A liquid flows to the surgical site and is aspirated along with the lens fragments. Although phacoemulsification is an improvement over earlier methods because it can be performed through a small incision, the surgical procedure is difficult and requires highly specialized surgical skills. In addition to the need to carefully control fluid flow through the surgical site, the heat and the vibration of the ultrasonic needle can damage adjacent ocular tissue. Clearly heat and vibration must be carefully controlled during the surgery. Thus, this technique has been found to be less than ideal and improvements in technique and equipment have been sought.
With the advent of the surgical laser, lasers have been adapted for use in ocular surgery. It has been found that the use of lasers in cataract surgery has somewhat alleviated the problems of ultrasonic phacoemulsification. With the use of lasers it is possible to construct the hand piece such that it is less bulky and more easily manipulated by a surgeon. This allows more surgeons to gain skill sufficient to manipulate the laser devices. At the same time, the laser does not create sonic vibrations that may cause damage to other tissue so that the risk of damage to the eye is reduced. Finally, there is less heat generated in the eye with the laser devices.
Even though the use of lasers in ocular surgery represents a large advance, there are still problems which arise. While heat and vibration are reduced over that experienced in ultrasonic phacoemulifiers, laser devices have the potential of damaging surrounding tissue through the generation of excess heat or release of deflected light and misdirected high energy laser beams. One problem arises from the fact that as laser light exits an optical fiber, the beam is dispersed. This stray light and other laser light that passes through the target tissue unabsorbed will continue beyond the surgical site. Such light, especially since it is generated by a relatively high powered laser, has the potential of damaging the eye and other tissues if not contained.
Attempts to control stray reflected light and misdirected laser beams have been largely ineffective. Traditionally, the control of misdirected light relies on the skill of the surgeon, not on any specific features designed into the surgical instrument.
In recent years laser surgical devices have been developed which attempt to control the passage of the laser beyond the surgical site. One such device has included a tip which extends distally from the point at which laser light is delivered to the surgical site. The tip extends outwardly and then turns upwardly such that it meets the laser beam exiting the fiber optic. In this manner, the laser beam is deflected such that the full strength of the laser beam does not pass beyond the surgical site. Even in this type of device, however, there is a danger of reflected or disbursed light causing damage, in that the tip of the device simply reflects and disburses the laser beam and provides no means to capture the light. Furthermore, at certain energy levels, the laser light can damage the reflecting tip itself.
Another deficiency of the prior laser devices relates to the configuration and positioning of the irrigation, aspiration, and laser systems. It will be appreciated that it is difficult to simultaneously deliver laser light and fluid to a surgical site, while at the same time providing fluid aspiration from the site. In certain device configurations, these functions can actually oppose one another. In such systems the various functions work against the other requiring more energy to break up the lens. At the same time, difficult design problems are presented in delivering the necessary functions to the surgical site in a manner that is easily controlled and directed by the surgeon. Existing systems are generally less than ideal in that regard.
Accordingly, it would be an advancement in the art to provide a surgical device which began to overcome the problems identified above. In particular, it would be an advancement i
Millar Robert M.
Motter Thomas F.
Smith Todd H.
Madson & Metcalf
Paradigm Medical Industries Inc.
Peffley Michael
Vrettakos P. J.
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