Abstract:
An ophthalmic endoillumination system comprises a self-contained power source and a laser light source powered by the self-contained power source to produce light. The system further comprises an elongated member sized for insertion into an eye and for conducting the light produced by the laser light source.

Description:
TECHNICAL FIELD 
     This disclosure relates in general to an endoillumination system and more particularly to an ophthalmic endoillumination system with a laser light source. 
     BACKGROUND 
     Anatomically, the eye is divided into two distinct parts—the anterior segment and the posterior segment. The anterior segment includes the lens and extends from the outermost layer of the cornea (the corneal endothelium) to the posterior of the lens capsule. The aqueous humour fills the space between the lens and the cornea and helps maintain intraocular pressure. The posterior segment includes the portion of the eye behind the lens capsule. The posterior segment extends from the anterior hyaloid face to the retina, with which the posterior hyaloid face of the vitreous body is in direct contact. The posterior segment is much larger than the anterior segment. 
     The posterior segment includes the vitreous body—a clear, colorless, gel-like substance. It makes up approximately two-thirds of the eye&#39;s volume, giving it form and shape before birth. It is composed of approximately 1% collagen and sodium hyaluronate and 99% water. The anterior boundary of the vitreous body is the anterior hyaloid face, which touches the posterior capsule of the lens, while the posterior hyaloid face forms its posterior boundary, and is in contact with the retina. The vitreous body is not free-flowing like the aqueous humor and has normal anatomic attachment sites. One of these sites is the vitreous base, which is a 3-4 mm wide hand that overlies the ora serrata. The optic nerve head, macula lutea, and vascular arcade are also sites of attachment. The vitreous body&#39;s major functions are to hold the retina in place, maintain the integrity and shape of the globe, absorb shock due to movement, and to give support for the lens posteriorly. In contrast to aqueous humor, the vitreous body is not continuously replaced. In a process known as vitreous syneresis, the collagen of the vitreous body may break down and result in retinal detachment. 
     Vitrectomy and other vitreoretinal surgical procedures are commonly performed in the posterior segment of the eye. Vitreo-retinal procedures are appropriate to treat many serious conditions of the posterior segment. Vitreo-retinal procedures treat conditions such as age-related macular degeneration (AMD), diabetic retinopathy and diabetic vitreous hemorrhage, macular hole, retinal detachment, epiretinal membrane, CMV retinitis, and many other ophthalmic conditions. 
     A surgeon performs vitreo-retinal procedures with a microscope and special lenses designed to provide a clear image of the posterior segment. Several tiny incisions just a millimeter or so in length are made on the sclera at the pars plana. The surgeon inserts microsurgical instruments through the incisions such as a minimally invasive light source to illuminate inside the eye, an infusion line to maintain the eye&#39;s shape during surgery, and instruments to cut and remove the vitreous body. 
     During such surgical procedures, proper illumination of the inside of the eye is important. Often, an endoilluminator containing a thin probe is inserted into the eye to provide the illumination. The probe may be optically connected to a light source, such as a metal halide lamp, a halogen lamp, or a xenon lamp, which is often used to produce the light carried by the optical probe into the eye. This endoillumination system configuration may be large, expensive, and non-portable. Alternatively, one or more light emitting diodes (LED&#39;s) may provide the light source for the optical probe. However, LED&#39;s may be unsuitable for use in some cordless, handheld devices because the power required to achieve sufficient luminance results in poor battery life and may generate enough heat to cause the handheld device to get dangerously hot. 
     New systems and methods are needed for illuminating the inside of the eye using a portable, high luminance light source. 
     SUMMARY 
     In one exemplary aspect, an ophthalmic endoillumination system comprises a self-contained power source and a laser light source powered by the self-contained power source to produce light. The system further comprises an elongated member sized for insertion into an eye and for conducting the light produced by the laser light source. 
     In another exemplary aspect, a method for endoillumination of an interior body region comprises selecting an endoillumination system. The endoillumination system includes a self-contained power source, a laser light source for producing light, and an elongated member sized for insertion into an eye and for conducting the light produced by the laser light source. The method further includes inserting at least a portion of the elongated member into the interior body region and illuminating the interior body region with the produced light from the laser light source. 
     In another exemplary aspect, an ophthalmic endoillumination system comprises a housing sized for carriage and manipulation by a human hand. The housing contains a battery and a laser light source for producing light. The system further comprises an elongated probe with proximal and distal ends. The proximal end is connected to the housing and the distal end is sized for insertion into an eye. The elongated probe includes a cannula sized to transmit the produced light. The system further comprises an optical component located at the distal end of the elongated probe to alter the angular dispersion of the produced light. 
     Further aspects, forms, embodiments, objects, features, benefits, and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an endoillumination system used for ophthalmic illumination. 
         FIGS. 2 and 3  are cross sectional schematic views of handheld endoillumination systems comprising a single laser light source according to embodiments of the present disclosure. 
         FIGS. 4-6  are perspective views of handheld endoillumination systems comprising multiple laser light sources according to embodiments of the present disclosure 
         FIG. 7  is a flowchart describing a method of ophthalmic illumination. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  shows an endoillumination system  100  including a cordless hand piece  102  and a probe  104 . As shown, probe  104  may be inserted into an eye  106  through an incision in the pars plana region. Probe  104  is used to illuminate the inside or vitreous region  108  of eye  106 . In this configuration, the probe  104  may be used, for example, to provide illumination for vitreo-retinal surgery. Other insertion locations and surgical procedures, including surgical procedures in other areas of the body, that will benefit from the use of endoillumination will be clear to a person having ordinary skill in the art. Various alternative embodiments of the endoillumination system will be described. 
     For example,  FIG. 2  shows an endoillumination system  120  which includes a handpiece  122  connected to a probe  124  by a connector  126 . The handpiece  122  provides a housing for a power source  128  and a laser light source  130 . Handpiece  122  may also include finger gripping surfaces or other ergonomic features (not shown) which allow the user to maintain a comfortable grasp and manipulate the probe  104  within an eye. The power source  128  is a self-contained power source such as a disposable battery, a rechargeable battery, a fuel cell, or other type of power source that is capable of operation without direct and continuous attachment to an electrical outlet, generator, or other centralized power source. The self-contained nature of the power source allows the endoillumination system  120  to be portable, cordless, and entirely handheld. 
     The laser light source  130  generates a light beam  132  which is received by an optical component  134 . In this embodiment, the optical component  134  is a condensing lens which may be, for example, a biconvex or plano-convex spherical lens, an aspheric lens, a ball lens, a gradient-index (GRIN) lens or any other type of device which can be used to focus a light beam for launching the beam into a small diameter optical fiber. 
     The laser light source  130  may be selected from several types of suitable lasers depending for example, upon the luminance, color, and power requirements needed. Suitable lasers may include gas lasers, semiconductor lasers, solid-state lasers, or other types known in the art. In this embodiment, the laser light source may be, for example, a diode-pumped solid state (DPSS) laser operating at a wavelength that produces green light. A diode-pumped solid state frequency doubled (DPSSFD) laser operating at approximately 532 nm may generate a particularly suitable monochromatic green output light. Using this configuration, approximately 11 lumens may be achieved at the retina using approximately 18 mW of light power. 
     The probe  124  includes a cannula  136  with an interior lumen  138  through which an optical fiber  140  extends. The cannula  136  may be formed from biocompatible materials and may be suitably thin and stiff for use within the vitreous region of the eye. In many embodiments, 19, 20, 23, 25, 27, or 29 gauge cannulas may be suitable. In certain embodiments, the fiber may be tapered or include other geometric features that modify the light beam. In alternative embodiments, the cannula may be omitted and the optical fiber may be used without this outer sheath. 
     The optical fiber  140  may be formed from a suitable glass or polymer material. Glass fiber may be particularly suitable due to its high transmittance. Glass is also a practical alternative to a polymer fiber when used in a portable, handheld device, because the light generating source is located in closer proximity to the distal end of the fiber. Because of the shorter distance involved, the optical fiber in a self-contained hand-held device may not require the same fiber flexibility as systems in which the light source is housed outside of the handpiece. The more efficient glass fiber may also be a suitable choice when used in the described laser/condensing lens configuration because the focused light beam emitted from the laser that is focused by the condensing lens may be efficiently coupled directly into a glass fiber without fiber modifications such as belling (i.e. lateral swelling) of the proximal end of the fiber. For example, a DPSSFD 532 nm laser typically has a relatively low M 2  factor of less than 1.2. This low M 2  factor corresponds to a high quality, focused light beam which may have a coupling efficiency of approximately 90%, including Fresnel reflection losses. 
     With the endoillumination system described in  FIG. 2  and in other embodiments of this disclosure, the overall power transfer efficiency (approximately 85-90%) may be higher than conventional vitreoretinal illuminators (often 60-70%). Also because the optical fiber spans a shorter distance and does not require significant modification to control the profile of the beam, the cost of the optical fiber may be reduced compared to conventional vitreoretinal illuminators. 
     In the embodiment of  FIG. 2 , the connector  126  allows the probe  124  to be disconnected from the handpiece  122 . This allows the handpiece  122  to be cleaned and reused while the probe  124  is discarded or separately sterilized. The connector  126  may be threaded, locking, snap-fit, or another type of connector known in the art. 
     In an alternative embodiment, as shown in  FIG. 3 , an endoillumination system  150  includes a handpiece  152  connected to a probe  154  by a connector  156 . The handpiece  152  provides a housing for a power source  158 , such as a battery, and a laser light source  160  which produces a light beam  162 . The laser light source may be substantially similar to the laser light source  130  described above. In this embodiment, the probe  154  may include a cannula  164  with an interior lumen  166 . Because the produced light beam  162  may be a tightly focused, collimated beam, the beam may pass through the cannula  164  without the use of an optical fiber. In this embodiment, a distal optical component  168  may be positioned at the distal end of the cannula  164  to control the spread of light across the patient&#39;s retina. Suitable optical components may include a condensing lens, a concave lens, a ball lens, and a graded index (GRIN) lens. It is understood that a distal optical component to control the angular dispersion of light may also be incorporated into embodiments in which an optical fiber is used. 
     In another embodiment, as shown in  FIG. 4 , an endoillumination system  170  includes a handpiece  172  connected to a probe  174 . The probe  174  includes a cannula  175  with an interior lumen  176 , which may be substantially similar to the cannula components described above. The handpiece  172  provides housing for a power source  177 , such as a battery, and a laser light source  178 . In this embodiment, the laser light source  178  includes three monochromatic laser light sources  180 ,  182 ,  184 . The laser light sources  180 ,  182 ,  184  may be selected from several types of suitable lasers depending, for example, upon the luminance, color, and power requirements needed. Suitable lasers may include gas lasers, semiconductor lasers, solid-state lasers, or other types known in the art. In this embodiment, the laser light sources may be, for example, DPSS lasers. 
     The laser light source  180  operates at a wavelength between approximately 625 and 740 nm, which produces a red output light. A laser diode operating between 650 and 670 nm may generate a particularly suitable monochromatic red output light. 
     The laser light source  184  operates at a wavelength between approximately 520 and 565 nm, which produces a green output light. Diode pumped solid-state (DPSS) lasers that transmit at approximately 532 nm may generate a particularly suitable monochromatic green output light. 
     The laser light source  182  operates at a wavelength between approximately 435 and 500 nm, which produces a blue output light. Suitable blue lasers may use, for example, InGaN semiconductor lasers or DPSS lasers to generate a suitable monochromatic blue output light at a frequency between the range of 445-475 nm. 
     The light from each of the laser light sources  180 ,  182 ,  184  is transmitted through optical components  186 , such as coupling lenses, to focus and/or direct the output light beams onto dedicated optical fibers  188  which extend through the interior lumen  176  of the cannula  175 . Suitable fibers may have a diameter of less than approximately 100 although larger fibers may be appropriate for certain applications. The optical fibers  188  may terminate within, at the distal end of, or past the distal end of the cannula  175 . The red, green, and blue light beams transmitted from the ends of the optical fibers  188  combine to generate a white, polychromatic, output light beam. In one example, 11 lumens of white light formed from a red beam at 632 nm, a green beam at 532 nm, and a blue beam at 473 nm would involve approximately 11 mW of red laser light, 14 mW of green laser light, and 11 mW of blue laser light, respectively. It is understood that additional optical components or optical fiber geometries (not shown) may be used to further direct and combine the monochromatic light beams into a white output beam. 
       FIG. 5  depicts an endoillumination system  190  which is substantially similar to the system  170 , but in this embodiment, the system further includes a connector  192  for removably connecting probe  194  to handpiece  196 . As describe above for  FIG. 2 , the use of a connector allows the handpiece to be reused and the probe to be disposable. 
       FIG. 6  depicts an endoillumination system  200  which includes a handpiece  202  connected to a probe  204 . The probe  204  includes a cannula  205  with an interior lumen  206 , which may be substantially similar to the cannula components described above. The handpiece  202  provides housing for a power source  207 , such as a battery, and a laser light source  208 . In this embodiment, the laser light source  208  includes three laser light sources  210 ,  212 ,  214  which operate to produce monochromatic red, blue, and green light, respectively. The red, blue and green light sources may be substantially similar to those described above for  FIG. 4 . 
     System  200  further includes optical components  216 ,  218 ,  220  to direct the laser light beams from the laser light sources  210 ,  212 ,  214 , respectively, toward a common point. In this embodiment, the optical components  216 ,  218 ,  220  are blazed diffraction gratings tuned to the particular wavelengths of the laser light sources. The diffraction gratings can be designed for near 100% diffraction efficiency and can direct the light beams toward the common point. The endoillumination system  200  further includes a set of optical components  222  which in this embodiment are a set of stacked gratings that redirect the three light beams to create a combined coaxial beam  224  of combined red, blue, and green light. This combined “white” laser beam is collimated and narrow enough to pass through the interior lumen  206  of the cannula  205  with high efficiency and without the need for an optical fiber. In alternate embodiments, however, an optical fiber may be used. The system  200  further includes an optical component  226  located at a distal end of the cannula  205  to angularly spread the light to illuminate the retina. In this embodiment, the optical component  226  is a ball lens. In certain embodiments, the optical component that controls the angular spread of the light beam may be adjustable in response to the control of an operator or in response to sensors positioned within the illuminated region. 
     It is understood that the specific optical components described for use in collimating, focusing, condensing, or dispersing light are merely examples and that other types of optical components including mirrors, digital micromirror devices (DMD&#39;s), lenses, filters, reflectors, gratings, or prisms may be employed to achieve the same function. For example, the optical component for combining red, green, and blue light beams may be a dichroic prism. 
     Referring now to  FIG. 7 , a method  250  for interior body illumination using one of the endoillumination systems previously described is provided. At step  252 , an appropriate endoillumination system is selected. Single monochromatic laser light sources such as those described in  FIGS. 2 and 3  may be more energy efficient and lightweight. Some practitioners may also find that monochromatic light allows for improved visualization and differentiation of retinal tissue. Although the coherent nature of monochromatic light may cause a speckled light appearance on the retinal tissue, some practitioners may find that this actually improves retinal feature discernment. The practitioner may choose the monochromatic color most suitable for the procedure to be performed. Shorter wavelength colors, such as blue, may present a potential aphakic hazard, so endoillumination systems using laser light sources that generate these colors may further incorporate tuning mechanisms, switches, timers, or other features to minimize the exposure of tissue to the more damaging wavelengths. Longer wavelength colors, such as red, may be perceived by the human eye as less bright compared to other colors at the same power levels. Thus laser light sources that generate red light may provide less perceived luminance compared to, for example, green light at the same power. 
     Polychromatic laser light sources such as those described in  FIGS. 4 ,  5 , and  6  may be selected by some practitioners who prefer to work with white light. Because white light includes a larger component of shorter wavelength light (e.g., blue light) than, for example pure green light, polychromatic laser light sources may also incorporate tuning mechanisms, switches, timers, or other features to minimize the exposure of tissue to the more damaging wavelengths. 
     The endoillumination system may also be selected based upon the angular spread of the light at the distal end of the cannula. For example, the angular spread of light needed to illuminate the interior working area of a human eye may be smaller than for the eye of a larger animal. Likewise the interior working area of another body region of the human body may require a larger angular spread. 
     At step  254 , the distal end of the probe is inserted into an interior body region, such as the eye. At step  256 , the interior body region is illuminated with the light from the laser light source. At step  258 , a quality of the light such as the angular dispersion, the color, or the brightness of the light may be adjusted. For embodiments that do not include adjustable quality parameters, this step may be omitted. After use, the endoillumination systems, such as those described in  FIGS. 2 ,  3 , and  5 , that include separable probes may be disassembled. The probe portion may be discarded and the handpiece portion may be cleaned and readied for another procedure. 
     Although several selected embodiments have been illustrated and described in detail, it will be understood that they are exemplary, and that a variety of substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the following claims.