Abstract:
A hand-held surgical light assembly is provided with a light source, and a handpiece which is adapted to be grasped and manipulated by a user. The handpiece has a light guide with a proximal end optically connected to the light source, and a distal end which projects outwardly from said handpiece so as to direct light guided thereby onto a field of view determined by manipulation of the handpiece by the user. The handpiece includes a switch assembly which is operatively coupled to the light source to allow user selection between at least two different light intensities (e.g., essentially on/off) discharged by said light guide onto the field of view. In preferred forms, the switch assembly includes an electrically conductive inner base member and an electrically conductive outer tubular elastomeric member concentrically positioned in surrounding, but spaced relationship, with the inner base member. When contact between the inner base member and the outer elastomeric member is made, switch circuitry changes the visible light intensity of the visible light generated by the light source, e.g., by either directly modulating the current to the lamp itself, or by providing an electrically operable shutter assembly which masks the light generated by the light source. The former embodiment is especially well suited for surgical lights which are self-contained (i.e., have the light sources contained in the handpiece), while the latter is especially well suited for surgical lights which have remotely positioned light sources.

Description:
This is a divisional of application Ser. No. 09/286,659, filed Apr. 6, 1999, now pending, the entire content of which is hereby incorporated by reference in this application. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to visible light-producing implements used in surgical arenas, especially during ophthalmic surgical procedures. In preferred forms, the present invention is embodied in a hand-held light that permits the surgeon (or other attending surgical personnel) to locally controllably adjust the emitted light intensity. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Photon energy delivered to the retina from intraocular fiberoptic instruments during ophthalmic surgical procedures can damage the retina. Retinal damage occasioned by such photon energy is known colloquially in the ophthalmic surgical art as “fight toxicity”. As a result, concerns have arisen over the amount of photon energy being delivered to the retina during a normal surgical procedure. For example, wavelengths from 400 nm to 700 nm are considered to be the safest for purposes of ophthalmic surgery. 
     However, even at these wavelengths, retinal damage can occur if retinal exposure to the photon energy is prolonged. In this regard, exposure of the retina to light emanating from intraocular fiberoptics during retinal surgery has, in some cases, resulted in pathologic retinal lesions, some of which have been associated with vision loss. Fiberoptic illumination of the retina, however, remains an essential component of vitreoretinal surgery in order for the surgeon to visualize the tissues undergoing the surgical procedure. 
     Although the use of visible light within the eye during ophthalmic surgery cannot be eliminated, the desire has been to reduce the amount of photon energy being delivered to the retina during a procedure. For example, light sources that have little of the most harmful wavelengths—i.e., light sources which emit little or no photon energy at wavelengths other than between 400-700 nm—have been employed. However, as noted previously, retinal damage can ensue if exposure is prolonged even at these relatively “safe” wavelengths. Furthermore, filters have also been placed in the light path of the light source so as to block the less safe wavelengths. Also, attempts have been made to diffuse the light over larger areas. 
     Conventional fiberoptic illuminators used to transmit photon energy during ophthalmic surgery are typically formed of polymethylmethacrylate (PMMA) having a nominal numeral aperture (NA) of about 0.66. Most of the energy from these conventional PMMA fiberoptic illuminators is within a 60° cone of light. Some special use fiberoptic lights use glass fibers that have similar optical properties. These conventional illuminators receive their light energy from a standard light source with matching optics allowing for good collection of the energy into the fiber. The fiberoptics are usually of an extended length (e.g., typically about six (6) feet in length) to allow the light emitting end to be used within the surgical field while the light source is maintained in a remote location. The fiberoptics are thus typically draped from the source to the operating field. Since several fiberoptic lights can be in use simultaneously during an operation, the fiberoptics tend to form a tangle of cables running onto the operating field, thereby providing practical complications. 
     Furthermore, during surgery, there exist the competing demands of providing the surgeon with adequate light to illuminate the surgical field, while at the same time permit relatively instantaneous adjustment of the illumination when desired to thereby reduce the photon energy delivered during periods when full illumination is not needed for the procedure. The surgeon can request that an assistant adjust the intensity of the light at the remotely positioned light source during portions of the surgery when this is feasible or can direct the light away from the most critical portion of the retina (the macula) during pauses in surgery. However, the former technique is problematic since surgical assistants are usually tasked with other responsibilities and thus may not be available to instantaneously adjust the light intensity at the surgeon&#39;s request. And, the latter technique may not always be available to the surgeon since the surgeon&#39;s hands may be occupied physically with another aspect of the surgical procedure which prevents redirection of the light. 
     Thus, as can be appreciated from the discussion above, improvements to surgical lights have been needed. It is towards providing such improvements that the present invention is directed. 
     Broadly, the present invention is embodied in hand-held surgical light assemblies having a light source, and a handpiece which is adapted to be grasped and manipulated by a user. The handpiece has a light guide with a proximal end optically connected to the light source, and a distal end which projects outwardly from said handpiece so as to direct light guided thereby onto a field of view determined by manipulation of the handpiece by the user. The handpiece includes a switch assembly which is operatively coupled to the light source to allow user selection between at least two different light intensities (e.g., essentially on/off) discharged by said light guide onto the field of view. 
     In preferred forms, the switch assembly includes an electrically conductive inner core and an electrically conductive outer tubular elastomeric member concentrically positioned in surrounding, but spaced relationship, with the inner base. When contact between the inner base and the outer elastomeric member is made, switch circuitry changes the visible light intensity of the visible light generated by the light source, e.g., by either directly modulating the current to the lamp itself, or by providing an electrically operable shutter assembly which masks the light generated by the light source. The former embodiment is especially well suited for surgical lights which are self-contained (i.e., have the light sources contained in the handpiece), while the latter is especially well suited for surgical lights which have remotely positioned light sources. 
     These, and other, aspects and advantages will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     Reference will hereinafter be made to the following drawings in which like reference numerals throughout the various FIGURES denote like structural elements, and wherein, 
     FIG. 1 is a perspective view of a particularly preferred embodiment of a self-contained hand-held surgical light in accordance with the present invention; 
     FIG. 2 is a longitudinal cross-sectional view, partly schematic, of the hand-held surgical light depicted in FIG. 1; 
     FIG. 3 is a perspective view of another embodiment of a handheld surgical light assembly in accordance with the present invention which is especially well suited for use in combination with a remotely positioned light source; 
     FIG. 4 is an enlarged longitudinal cross-sectional elevation view of the handpiece of the embodiment depicted in FIG. 3; 
     FIG. 5 is a schematic depiction of a control circuit that may be employed in connection with the switches associated with hand-held surgical light embodiments in accordance with the present invention; 
     FIGS. 6A and 6B respectively depict different operational states of a shutter assembly that may be employed in operative association with the remotely positioned light source used in surgical light assembly depicted in FIG. 3; 
     FIGS. 7A and 7B respectively depict different operational states of another shutter assembly that may be employed in operative association with the remotely positioned light source used in surgical light assembly depicted in FIG. 3; 
     FIGS. 8A and 8B are end elevational views of the shutter states depicted in FIGS. 7A and 7B, respectively, as taken along lines  8 A— 8 A and  8 B— 8 B therein; 
     FIG. 9 is a rear perspective view of an embodiment of a rotary shutter assembly that may be employed in the surgical light assembly depicted in FIG. 3; and 
     FIG. 10 is a rear cross-sectional elevational schematic view of an embodiment of a rectilinearly moveable shutter assembly that may be employed in the surgical light assembly depicted in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One preferred embodiment of a hand-held surgical light  10  in accordance with the present invention is depicted in accompanying FIGS. 1 and 2. The surgical light  10  shown in FIGS. 1 and 2 generally includes a proximal handle section  12  which is sized and configured to be held comfortably in a surgeon&#39;s hand, a distal end section  14 , and a light guide section  16  protruding distally from the end section  14 . 
     The embodiment of the surgical light  10  shown in accompanying FIGS. 1 and 2 is self-contained. That is, the surgical light  10  includes all operational components such as power source  20  (e.g., preferably in the form of a conventional rechargeable battery), a light source  22  (e.g., a conventional incandescent microbulb), and the electronic switch circuitry  24  are contained within the handle section  12 , while a mechanical membrane switch  26  is positioned operatively in the distal end section  14 . 
     The light source  22  includes an ellipsoid mirror (not shown) which focuses the light onto the distally positioned conically shaped mirror  24 - 1 . The light then passes through a wave-length filter  24 - 2  where potentially harmful wavelengths are filtered therefrom (e.g., so that only photon energy having a wavelength between 400-700 nm passes through the filter  24 - 2 ). The filtered light is then directed into the proximal end of the light guide section  16  which is held securely within the distal tip section  14  of the surgical light  10 . 
     The filtered light then propagates along the light guide section  16  and is discharged from its distal tip onto the surgical field as directed manually by the surgeon holding the light  10 . Most preferably, the light guide section includes a  19  gauge stainless steel (type  304 ) tubing in which a light conducting fiber is positionally fixed (e.g., by suitable bonding adhesive). The light conducting fiber is most preferably 0.75 mm diameter and has a numerical aperture of about 0.6. 
     An electrical switch on the handle assembly will, when manually activated, cause the intensity of the light emitted by the light source  22  to change. The preferred switch according to this invention is a mechanical membrane switch  26  which is comprised generally of an outer electrically conductive tubular elastomeric membrane sleeve  26 - 1  and an inner electrically conductive generally cylindrical metal member  26 - 2 . The membrane sleeve  26 - 1  is most advantageously is about 0.040 inch thick and has a hardness of about  55  Durometer and a resistance value of about 10 Kohms per square. One preferred electrically conductive elastomeric sleeve that may be employed is Product No. F00120880000 commercially available from Patter Products Inc. of Beaverton, Mich. The electrically conductive base member  26 - 2  is most preferably aluminum, for example, 6061 aluminum alloy. 
     As shown, the outer membrane sleeve  26 - 1  is separated from the inner conductive base member  26 - 2  by an annular space. In use, therefore, the surgeon will depress the membrane sleeve  26 - 1  until it contacts physically the base member  26 - 2  thereby electrically closing the switch  26 . The switch circuitry  24  (to be explained in greater detail below with regard to FIG. 5) is electrically connected to the switch via internal wiring  28  and will therefore sense this switch closure. Generally, the switch circuitry will change the intensity of the light emitted by the light source  22  in a step-wise manner in response to switch closure. In this way, the surgeon can manually and selectively control the intensity of the light emitted from the distal end of the light guide section  16 . 
     Accompanying FIGS. 3-4 show another embodiment of a hand-held surgical light  50  in accordance with the present invention. One principal difference between the surgical light  50  depicted in FIGS. 3-4, and the surgical light  10  depicted in FIGS. 1-2 is that the former is not self-contained. Instead, the surgical light  50  includes a remotely located light source  52  which is optically coupled through a shutter assembly  53  to a light probe handpiece  54  via conventional primary optical light guide  56 . 
     The handpiece  54  includes a proximal cylindrical handle section  54 - 1  sized and configured to allow a surgeon to manually manipulate it during surgical operations and a tapered distal end section  54 - 2 . A light guide section  58  similar to the light guide section  16  discussed previously protrudes outwardly from the distal end section  54 - 2  of the handpiece  54 . The light guide section  58  is optically coupled to the light guide  56  by means of a proximal, and unitary, section  58 - 1 . The handpiece may be coupled/uncoupled from the primary light guide  56  by an optical coupler  57 . 
     According to the present invention, the handpiece  54  carries an electrical switch which, according to the present invention, is most preferably a membrane switch assembly  70 . As shown in FIGS. 3 and 4, the membrane switch assembly  70  is sized so as to be sleeved over the handle section  54 - 1  and be in friction-fit engagement therewith. As is perhaps better seen in FIG. 4, the membrane switch  70  includes an outer conductive tubular elastomeric membrane sleeve  70 - 1  which concentrically surrounds an inner cylindrical electrically conductive metal base member  70 - 2 . In its normal (non-active) condition, therefore, an annular space is defined between the membrane sleeve  70 - 1  and the base member  70 - 2 . The membrane sleeve  70 - 1  and base member  70 - 2  are electrically isolated from one another while in a normal condition by proximal and distal mounting rings  70 - 3  and  70 - 4 , respectively. which are separated from one another along the axial direction of the handpiece  50 . Most preferably, the electrically conductive elastomeric membrane sleeve  70 - 1  has the same dimensions and properties as that described above with reference to membrane sleeve  26 - 1  associated operatively with the surgical light  10 . The membrane switch  70  is electrically connected to the switch circuitry  100  via electrical wiring  70 - 5  traced along the optical light guide  56 . Particularly, the switch circuitry  100  may be electrically coupled to a solenoid coil  102  (not shown in FIG. 3, but see FIG. 5) associated operatively with the shutter assembly  53 . 
     Accompanying FIG. 5 depicts an exemplary switching circuit that may be employed as the switch circuit  100  depicted in FIG. 3 or the switch circuit  24  depicted in FIG.  2 . Thus, the switch circuit  100  or  24  may operate alternatively a solenoid coil  102  (i.e., if employed in the hand-held surgical light  50 ) or a light assembly  22  (i.e., if employed in the hand-held surgical light  10 ), respectively. In this regard, as discussed previously, the mechanical membrane switch  26  (associated with the surgical light  10 ) or  70  (associated with the surgical light  50 ) may be activated by the surgeon to effect a change in light intensity in a step-wise manner (most preferably to toggle between on/off states). The membrane switch  26  or  70  is electrically coupled to a flip-flop semiconductor device  108  that controls whether current flows through the switching solenoid coil  102  or light  22  by activating a transistor  110 . 
     The membrane switch applies a reference voltage  112  to the clock input of the flip-flop  108 . When the clock signal is high, i.e., reference voltage supplied by the membrane switch, the flip-flop is enabled. Enabling the flip-flop does not by itself cause the outputs  114 ,  116  to change. The state of the outputs (Q, Q-bar) depends on the data input  118  at the moment the flip-flop  108  is enabled. If the data input is high, then the output (Q)  114  will be switched high when the flip-flop is enabled by the membrane switch. As the output (Q) goes high, then transistor  110  is turned on and current flows through the solenoid coil  102  or light  22 . 
     When the data input  118  is high at the moment the flip-flop  108  is enabled, the inverted output (Q-bar)  116  is switched low. The low state of the Q-bar output will cause the data input  118  to fall to a low state due to the operation of the resistor  122  and capacitor circuit  120  (R/C) connected between the Q-bar output and data input. As long as the data input remains high and capacitor  120  has not discharged, subsequent transitions of the enable signal such as those caused by bounce or uncertain pressure on the membrane switch will cause the Q output  114  to remain high, and transistor  110  will continue to conduct current through the solenoid coil  102  or light  22 . After a period of time sufficient for capacitor  110  to discharge through resistor  122  to the Q-bar output  116  and allow the data input  118  to go low, a subsequent closure of the membrane switch will switch the Q output  114  low (and the Q-bar output high). This will turn off transistor  110 , which will therefore turn off solenoid coil  102  or light  22 . The action of resistor  122  and capacitor  120  will delay the change of data input  118  to the level of Q-bar output  116  as in the previous case, thereby again providing immunity to inadvertent enable signals caused by bounce or uncertain pressure on the membrane switch. This allows the surgeon to turn the light on or off by a momentary activation of the switch, and not have to maintain continuous pressure on the switch. Combining a multiplicity of circuits similar to this, in ways which are completely understood by those skilled in this art, allows for multiple levels of illumination to be selected by the surgeon. 
     The solenoid coil  102  can be associated operatively with a variety of mechanical shutter systems  53 , some embodiments of which will be described below, in combination with the mechanical membrane switch  70 . Thus, for example, the shutter assembly  53  may include a shuttle member  135  which is fixed to, and moves axially within the solenoid coil  102 . On energization (e.g., by closing the membrane switch  70  as discussed above), as shown in FIG. 6A, the solenoid may drive the proximal section  56 - 1  of the light guide  56  toward the rear face  140 - 1  of the optical coupling  140  which couples the light guide  56  to the light source  52 . In this condition, the full intensity of the light produced by the light source  52  is allowed to enter and be transferred along the light guide  56 . When deenergized (e.g., by closing the membrane switch  70  a subsequent time), the shuttle  135  may be driven in an opposite axial direction as shown in FIG.  6 B. In response, therefore, the proximal end section  56 - 1  of the light guide  56  is recessed within the coupling  140  (i.e., is withdrawn from the face  140 - 1 ) thereby diminishing the intensity of the light from light source  52  which is allowed to be propagated along the light guide  56 . 
     Another possible shutter assembly  53  is depicted in accompanying FIGS. 7A-7B and  8 A- 8 B. In this embodiment, the shutter assembly  53  includes a shuttle member  135  which is coaxially moveable between a retracted position (as shown in FIGS. 7A and 8A) and an advanced position (as shown in FIGS. 7B and 8B) within the solenoid coil  102  so as to allow maximum and minimum light intensity to be received by the proximal end section  56 - 1  of the light guide  56 . The solenoid coil  102  is fixed to, and axially spaced from the optical coupling  140  by means of a bridge member  142 . A flexible shutter band  150  is attached physically at one end  150 - 1  to the shuttle member  135  and has an opposite end  150 - 2  which is capable of covering the entranceway  140 - 2  to the proximal light guide section  56 - 1  when the light guide is in its extended position (i.e., as shown in FIGS.  7 B and  8 B). In this regard, the shutter band  150  is formed of a shape-retaining material and is most preferably bent or curved at the end  150 - 2  so that, when it protrudes rearwardly from the face  140 - 1  of the coupling  140 , it will bend over and cover the entranceway to the light guide section  56 - 1 . Thus, operating the membrane switch  70  will responsively cause the terminal end  150 - 2  of the shutter band  150  to respectively be in either a covered and uncovered relationship with respect to the light guide section  56 - 1  thereby minimizing and maximizing the light it receives from the light source  52 . 
     FIG. 9 depicts another shutter assembly  53  that may be employed in the practice of this invention. In this regard, instead of an axially operable shutter mechanism, the solenoid coil  102  is operable in a rotary direction. The solenoid coil  102  is connected to a proximal end of a drive shaft  160  which extends the entire length of the optical coupling member  104 . A paddle-type shutter member  162  is fixed to the distal end of the drive shaft  160 . As shown in FIG. 9, operation of the membrane switch  70  causes the solenoid to activate which responsively rotates the drive shaft  160  and thereby swings the paddle-type shutter member  162  into and out of covering relationship with the entranceway  104 - 2  to the light guide  56  formed in the face  104 - 1  of the optical coupling  104 . The intensity of the light emitted by the light guide section  58  is thereby minimized and maximized, respectively. 
     Another paddle-type shutter member  170  is depicted in the shutter assembly  53  shown in FIG.  10 . In this regard, the shutter member  170  is connected operatively to a solenoid coil  102  which redially reciprocally moves the shutter member  170  into and out of covering relationships with the entranceway  140 - 2  of the light guide  56  formed in the face  140 - 1  of the optical coupling member  140 . Again, therefore, according to the shutter embodiment depicted in FIG. 10, activation of the switch  70  will responsively cause the shutter member  170  to cover and uncover the light guide entranceway  140 - 2  thereby minimising and maximizing the intensity of light discharged from the light guide section  58 . 
     Other equivalent forms and/or embodiments of the present invention, for example, other forms and/or embodiments of the switch assemblies, shutter assembly, and the like, may be envisioned by those skilled in this art. Therefore, while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.