US 20070121069 A1
A laser indirect ophthalmoscope (LIO) apparatus for photomedical treatment and/or diagnosis is presented. The LIO apparatus allows multiple spot ophthalmic surgery to be performed in a wider range of patient positions and less intrusively than currently available methods. The LIO apparatus utilizes a separate or integral beam multiplier that generates one or more optical beams via spatial and/or temporal separation, and an optical system that conditions and directs the one or more optical beams to a target to form a pattern. The LIO apparatus includes a headset, and is therefore wearable by the user (e.g., a physician).
1. An apparatus for photomedical treatment or diagnosis of a target tissue, the apparatus comprising:
a light source for generating light;
a headset designed to be Worn by a user, wherein the headset includes an input for receiving the light and an output for projecting the light on a target tissue;
a beam multiplier positioned for receiving the light and for generating one or more optical beams by spatial and/or temporal separation of the light for projection thereof via the output on the target tissue in the form of a pattern.
2. The apparatus of
3. The apparatus of
4. The apparatus of
5. The apparatus of
6. The apparatus of
7. The apparatus of
8. The apparatus of
9. The apparatus of
10. The apparatus of
a first scanner for deflecting the light in a first direction; and
a second scanner for deflecting the light in a second direction perpendicular to the first direction.
11. The apparatus of
12. The apparatus of
13. The apparatus of
14. The apparatus of
15. The apparatus of
16. The apparatus of
17. The apparatus of
18. The apparatus of
19. The apparatus of
20. The apparatus of
21. The apparatus of
22. The apparatus of
a plurality of optical fibers.
23. The apparatus of
a scanning element for sequentially delivering the light to one or more of the plurality of optical fibers.
24. The apparatus of
a first optical fiber;
a plurality of optical fibers; and
a fiber splitter for receiving the light from the first optical fiber and directing the light to the plurality of optical fibers.
25. The apparatus of
a first optical fiber;
a plurality of optical fibers; and
a fiber switch for receiving the light from the first optical fiber and sequentially directing the light to the plurality of optical fibers.
26. The apparatus of
a controller for controlling the light source.
27. The system of
28. The system of
29. The system of
30. The system of
a second light source for generating an aiming beam that is combined with the light.
31. The system of
32. A method of treating target tissue, comprising:
conveying the light to a head mountable LIO apparatus having an input for receiving the light and an output;
converting the light to one or more optical beams in the form of a pattern using a beam multiplier that spatially and/or temporally separates the light; and
projecting the pattern of the one or more optical beams to target tissue.
33. The method of
34. The method of
35. The method of
scanning the light to create the pattern.
36. The method of
37. The method of
splitting the light into the optical beams for simultaneous impingement of the optical beams on the target tissue.
This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Ser. No. 60/737,548, filed on Nov. 16, 2005, the entire content of which is incorporated herein by reference.
The present invention relates generally to patterned photothermal treatment of retinal tissue and particularly to such treatment using a laser indirect ophthalmoscope.
Conditions such as diabetic retinopathy and age-related macular degeneration are subject to photocoagulative treatment with laser light. While this type of laser light treatment slows the damage rate of the underlying disease, it has its set of problems. For example, because the treatment entails exposing the eye to a large number of laser light pulses for a long period of time (typically each pulse is on the order of 100 ms), damage can be caused to the patient's sensory retina from the heat that is generated. During the treatment, heat is generated predominantly in the retinal pigmented epithelium (RPE), which is the melanin-containing layer of the retina directly beneath the photoreceptors of the sensory retina. Although visible light is predominantly absorbed in the RPE, this type of treatment irreversibly damages the overlying sensory retina and negatively affects the patient's vision.
A slit-lamp-mounted laser delivery device is commonly used for this type of laser light treatment. In this device, the slit lamp is arranged to allow easy illumination and microscopic viewing of the eye of a seated patient. Slit lamps used in laser treatment/surgery include a high-brightness illuminator and microscope assemblies mounted on a shared pivot point. This arrangement allows the viewing angle of the microscope and illuminator to be changed as often as desired without moving the field of illumination or visualization transversely.
Slit-lamp-mounted laser delivery devices have their shortcomings. Specifically, certain parts of the eye are difficult to treat with this type of device. For example, the anterior aspect of a retinal break is by far the most important part to seal, as this is the area most subjected to vitreous traction. However, this area is not completely accessible with a slit-lamp-delivered laser system. Also, the slit-lamp-mounted laser delivery device is not well suited for treating small infants or bed-ridden patients. Furthermore, it is difficult to orient the patient's head position with slit-lamp-mounted systems. Thus, these devices have limited ability to treat patients with detached retinas and other conditions where gas or dense fluids have been introduced into the eye to secure detached tissues prior to laser exposure. To treat these conditions, the patient's head is oriented to reposition the tissue or tamponade material.
Accordingly, there is a need for a flexible and time-efficient approach to retinal photocoagulation with an LIO that is not provided by known methods or apparatus.
The present invention is an improved device and method for patterned photothermal treatment of retinal tissue utilizing a laser indirect ophthalmoscope.
An apparatus for photomedical treatment or diagnosis of a target tissue includes a light source for generating light, a headset designed to be worn by a user wherein the headset includes an input for receiving the light and an output for projecting the light on a target tissue, and a beam multiplier positioned for receiving the light and for generating one or more optical beams by spatial and/or temporal separation of the light for projection thereof via the output on the target tissue in the form of a pattern.
A method of treating target tissue includes generating light, conveying the light to a head mountable LIO apparatus having an input for receiving the light and an output, converting the light to one or more optical beams in the form of a pattern using a beam multiplier that spatially and/or temporally separates the light, and projecting the pattern of the one or more optical beams to target tissue.
Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.
Multiple spot laser therapy is known. For example, U.S. Pat. No. 4,884,884 by Reis discloses “beam multiplication” by various means. U.S. Pat. No. 5,921,981 by Bahmanyar and Jones discloses a slit-lamp based delivery device and intraocular probes only for multiple spot treatments. U.S. Pat. Nos. 6,066,128; and 6,096,028 by the same inventors cover only intraocular probes. However, multiple spot laser therapy is limited in application because it is performed utilizing slit-lamp delivery device (shown in
This invention is based on multiple spot laser therapy using a Laser Indirect Ophthalmoscope (LIO). Using the LIO allows multiple spot laser therapy to be performed without intrusive probe insertions. Moreover, because the LIO allows the physician to treat patients in the supine position, the invention adds flexibility to multiple spot laser therapy.
The light generation unit 15 includes a light source 10. The light source 10 may be a diode-pumped solid state laser, gaseous laser, semiconductor laser, light emitting diode, flash lamp, etc. The light source 10 is controlled by the CPU 12 via the input and output (I/O) device 14 to create an optical beam 11, whose centerline is shown by dashed lines. The optical beam 11, upon being generated by the light source 10, encounters mirror M1 which directs a first portion of the optical beam 11 to a photodiode PD1. The photodiode PD1 may be replaced with other types of sensors, as appropriate. The photodiode PD1 serves to sample and measure the power of the light for safety purposes. A second portion of the light from the mirror M1 that is not directed to the photodiode PD1 goes to a shutter S, which acts as a gate to the optical beam 11. The shutter S controls the optical beam 11 to produce discrete spots or a continuous supply of the optical beam to create continuous scans as a means to produce the desired pattern. If the shutter S blocks the light, the optical beam 11 does not travel further. On the other hand, if the shutter S lets the light pass, the optical beam 11 goes on to mirror M2 and mirror M3. Mirror M2 is a turning mirror that may be used in conjunction with mirror M3 to align the optical beam 11 into the fiber unit 42.
Multiple spot laser therapy may be performed using an optional aiming beam in addition to a treatment beam. The aiming beam is used to indicate the location of the beam on the target tissue 1. It may be coincident upon the treatment beam, or provide an outline (or other indication) of the area to be treated. Where an aiming beam is used in addition to the treatment beam, the optical beam 11 generated by the light source 10 is the treatment beam, and a separate aiming beam is produced by an aiming light source 17. The aiming light source 17 preferably produces light of a different wavelength than the light source 10. Once the treatment beam is aligned with the aiming beam, the treatment beam is delivered for treatment of the eye. Each of the aiming beam and the treatment beam may include a single spot of light, multiple discrete spots, or continuous pattern(s) of light.
The aiming beam and the optical beam may be interleaved by gating the light beams on and off. Each spot of light may be round or have some other shape. The aiming beam and the treatment beam do not need to be produced simultaneously. Mirror M3 combines the aiming beam with the optical beam 11 and directs the combined light into the fiber unit 42 via the lens L1. The lens L1 is used to inject the optical beam 11 into the optical fiber unit 42.
Although use of an aiming beam is contemplated as an option, the description herein will focus on the optical beam 11 for simplicity of illustration. Where an aiming beam is used, the optical beam 11 that is received by optical fiber unit 42 is a combination of the aiming beam and the treatment beam.
If the light source 10 produces visible (or otherwise aim quality) light, it may also be used for producing the alignment pattern, making a separate aiming light source 17 unnecessary. The alignment pattern coincides with portions of the eye 1 that will later be illuminated with the optical beam 11 and ensures that the system is properly aligned to the target portion(s) of the eye 1.
The optical beam 11 is transmitted to the LIO assembly 16 via an optical fiber unit 42. A pattern generator assembly 18, where lens L2 acts as the optical input for receiving the optical beam, and mirror M4 acts as the optical output for projecting the beam onto the target tissue, in the LIO apparatus 16 receives the optical beam 11 and directs the optical beam 11 toward the target—i.e., the retina R of the patient's eye 1. The optical beam 11 is focused on the eye 1 and perceived by the patient. A pattern (which may be predetermined) is disposed at the patient's retina R. The position and character of the pattern may be controlled by use of an input device 20 (e.g., a remote control panel) or other user interface, such as graphical user interface (GUI) 36. A person of ordinary skill in the art would understand that the disposition of the optical beam 11 is a function of the optics of the photomedical system 100 and any particular conditions of the patient. Particular conditions that may affect the ultimate disposition of the optical beam 11 include cataracts, retinal inhomogeneities, and intraocular debris, among others.
Lenses L2, L3, and L4 of the pattern generator assembly 18 function to condition and direct the optical beam 11 to the patient's eye 1. Light exiting the optical fiber unit 42 first encounters lens L2 and becomes, for example, collimated before entering the lens L3. Lens L3 may be a single lens or a compound lens, and can be configured as a zoom lens for adjusting the intrinsic size of the beam that comprises the pattern. The light coming out of the lens L3 passes through the beam multiplier BM and enters the lens L4. The beam multiplier BM produces a pattern of multiple spots or a scanned pattern.
When the mirror M4 is small, it may be placed directly in the visualization path 33 without much disturbance. Mirror M4 may also be placed in the center of a binocular imaging apparatus without substantially disturbing the visualization. Lens L4 could also be placed one focal length away from the optical midpoint of the scanning optics to produce a telecentric scan, such as is required for optimal performance by certain choices of ophthalmic lens 19. In this case, the mirror M4 would need to be large enough to contain the entire scan, and could be made as a high reflector spectrally matched to the output of light sources 10 and 17, if used. Visualization 34 of the target zone of the eye is accomplished by viewing through the mirror M4. A further refinement would be to white balance the transmission of mirror M4, making it photopically neutral, by using a more complicated optical coating that makes the transmitted image appear more natural rather than, for example, pinkish when using a green notch filter coating on mirror M4 as would be required when light source 10 produces green light. Visualization system 98 is contained in the LIO assembly 16, and allows the user to visualize the retina R of patient eye 1, preferably with both eyes of the user.
In some embodiments, the CPU 12 also controls the movement of mirror M4 thus controlling the location of the beam/pattern on the target tissue 1. The optical scan to form the pattern can be created in a number of different ways, such as by moving the light source 10, moving the mirror M4, using one or more rotating wedges, using acousto-optic deflector(s), or galvanometric scanner(s), etc. Preferably, mirror M4 may be rotated as already described, or in the case of a mirror with surface curvature (optical power), it may also be translated to produce optical deviation. In the case where mirror M4 has optical power, compensating optical elements (not shown) may be required to produce an image, as opposed to simple illumination as shown. The perception of both discrete spots and spot blinking may be accomplished by scanning quickly between elements of the pattern so as to limit the amount of light registered by the patient and observed in those intermediate spaces.
The pattern may also be used to fixate the patient so that the patient looks at a fixed position away from the optical axis of the physician's visualization and light delivery system, thereby keeping the patient's eye still, and also providing the physician direct optical access to the retinal periphery. Small motions of the pattern may be used to minimize actual eye movement while still capturing the patient's attention. This technique may be especially useful in situations such as pan retinal laser photocoagulation treatment where slight eye movement can be tolerated. Slightly moving the pattern about a center position to attract the patient's attention makes it easy for the patient to fixate on the pattern. Ensuring fixation is especially important during procedures such as macular grid laser photocoagulation treatment, where unintended laser exposure to the central vision is to be avoided.
The ophthalmic lens 19 aids in the user 34 visualization of the retina and creates a magnified intermediate image of retina R at location IP. The ophthalmic lens 19 may then serve to help relay the beam/pattern to retina R. The beam thus relayed to the target tissue 1 will be magnified by the inverse of the image magnification of ophthalmic lens 19. The ophthalmic lens 19 may be a contact or non-contact lens, and may also be used in conjunction with the lens L4 to provide for conjugate pupil planes such that the scanning pivots about the patient's iris, thus maximizing the system's retinal scan field.
There are different ways the beam multiplier BM may produce multiple spots. One way of producing multiple spots is to employ the beam multiplier BM in the LIO assembly 16 as shown in
The beam may be multiplied simultaneously, scanned to ultimately produce a pattern of delivered spots, or both. Thus, as used herein, “beam multiplication” by beam multiplier BM applies to simultaneous beam multiplication (e.g., by dividing a beam into multiple sub-beams—spatial separation), beam scanning (e.g., beam spots or pattern are projected or formed sequentially—temporal separation), or any combination of the two.
Using diffractive or refractive elements to deviate the beam yields different results for different wavelengths. This sensitivity to wavelength complicates the use of a different-colored aiming beam and multi-spectral treatment sources. Thus, when more than one wavelength is used, such as in the case of
The components described in
The device of the invention allows the treatment time to be reduced by a factor that is approximately equal to the number of pulses delivered, whether the pulses are delivered simultaneously or sequentially. Simultaneous delivery has the advantage of being faster than sequential delivery, but requires a light source capable of delivering n times the output power, wherein n is the number of elements in the pattern. Sequential delivery, while being slower than simultaneous delivery, places less demand on the power of the light source and provides flexible adjustment of the ultimate delivery pattern. Both simultaneous and sequential deliveries with the device of the invention significantly reduce the treatment time and the placement precision of the lesions when compared to the manual technique that is conventional today. The eye can be considered stationary for approximately one second, the “fixation time.” The number of spots that can be delivered sequentially in this fixation time is inversely proportional to their pulse duration.
A “pattern,” as defined herein is meant to include either the simultaneous or sequential delivery of a plurality of spots, such as those shown in
Although the invention has been described with reference to the above examples, it will be understood that modifications and variations are encompassed within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims.