WO2006025806A1

WO2006025806A1 - Apparatus for reversal of presbyopia using thermal lasers focused on zonules

Info

Publication number: WO2006025806A1
Application number: PCT/US2003/000264
Authority: WO
Inventors: J. T. Lin; Heraldo Sa Martins
Original assignee: Lin J T; Heraldo Sa Martins
Priority date: 2003-01-07
Filing date: 2003-01-07
Publication date: 2006-03-09

Abstract

A method and apparatus for presbyopia correction are disclosed. The disclosed preferred embodiments of the system consists of a beam delivery device (gonio lens 24), a slit lamp (26), and a selected laser (21) having a wavelength of (0.5 - 0.7) microns and (0.9 - 1.3) microns. Presbyopia is treated by the thermal contraction of the human zonules with a temperature increase of about (15-50) degree-C generated by the selected lasers. The selected laser is focused and delivered by a gonio lens to the targeted zonules area (14) and viewed by a surgeon using a slit lamp. The selected laser having an optimal absorption characteristics is tightly focused such that only the target zonules are heated, while the cornea (11), the lens body and the adjacent areas are not damaged. Laser energy may be absorbed either by collagen or injected dye in the zonule.

Description

APPARATUS FOR REVERSAL OF PRESBYOPIA USING THERMAL LASERS FOCUSED ON ZONULES

BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to apparatus for effecting controlled thermal contraction or shrinkage of zonnular tissue fibers to provide a non-invasive reversal of presbyopia , by means of a selective laser which is focused and delivered by a special device

2 Brief Description of the Prior Art Presbyopia has been a challenging disease for medicine Eye glasses and contact lens are the most common method of compensating for presbyopia Multifocal intraocular lens also have been employed but restricted to cataract patients These procedures merely compensate for presbyopia , instead of restoring accommodation Therefore, the suitable procedures for presbyopia patients to be cured are limited to those methods which involve reversal of presbyopia by acting upon the area of lens, zonules, ciliary body, and sclera Reshaping ths cornea with an excimer laser to form bifocal shape produces glare, halos and unacceptable monocular diplopia Procedures for presbyopic correction using insertion of πgid bands were proposed by R A Schachar in US Pat 5,529,076, 5,489,299 and 5,722,952 In the prior arts of Schachar a multitude of claims were made, being the great majority restricted to abstractions Specially in US Pat 5,503, 165 it claims to cover all lasers from the electromagnetic spectrum for contracting the zonules and reversing presbyopia Contracting the zonules to reverse presbyopia is a tangible medical method However the zonules are deprived of pigment and therefore can not be heated by many of the lasers cited by Schachar's prior arts It is further believed that Schachar had incorrectly assumed that all lasers will act on pigment-free tissues such as the zonules Many of the lasers cited by the pπor arts of Schachar are photoablative and simply would not cause thermal effects on the zonules Furthermore, in these pπor arts, there was no mention of any specific laser parameters which is capable of causing the thermal shrinkage of the zonules and only abstract idea was suggested which covered all existing lasers On the other hand, one of the present inventors (Martins), filed a US patent application called "Laserthermozonnuloplasty" on January 23, 1997, US Appl No 08/792,848, descπbing the idea of laser presbyopia reversal This patent was abandoned later by the present author in virtue of the fact that, just as Schachar's, it was only an abstraction and lack of specific laser parameters and the focusing means to restrict the laser thermal energy to the target tissue (zonules) It is also essential that a laser beam must be focused such that only the selected area on the zonules will absorb the laser therma-encrgy, whereas the remaining areas are not affected Without specifying the laser parameters and its deUvery means (such as a gonio lens), I he abstraction suggested by the pπor arts will not provide a clinically useful system Furthermore, non of the idea suggested by the pπor arts has been tested by a device The gonio lens is a cπtical element of the present invention, where the laser beam is reflected and delivered to the targeted zonules area without cause damage to the ins or crystal lens It would be either impossible or very difficult for the laser to reach the targeted area without using this gonio lens One of the present inventors (Lin) also proposed the use of lasers for presbyopic corrections by removal of a portion of the scleral tissue over the ciliary body, US Pat 6,258,082, 6,263,879 and PCT/US01/24618 These methods, however, are invasive and laser ablation depth is cπtical for the clinical outcome and safety It is one of the objects of the present invention to provide a laser system which offers a non-invasive method and apparatus to correct presbyopia It is specific in the mode and applicable pπnciples It describes the manner and process of making and using a laser and related accessories in order to achieve zonnular contraction, concisely and exactly The proposed method shall apply to out-patients and involves no implanting, no tissue cutting or ablating, no suturing, no bleeding and can be performed easily and fast It is yet another object of the present invention to provide the details of a mean to deliver the laser to the targeted-area without significant damage to the other surrounding tissues Specific laser spot size, beam focusing and tissue absorption are cπtical in the proposed method for safety and clinical outcomes The desire is to heat selected areas of πch in collagen tissue to a shπnkage level, but without damage or destruction of either the target or surrounding tissues In other words, the selective laser is used to irradiate the zonules tissue with energy such that the temperature of the collagen tissue is raised sufficiently to cause the tissue to shrink but not so high as to cause any substantial damage The thermal shπnkage of the selected zonules area of the eye will cause the zonules to change its shape, decreasing its length, and then reverse presbyopia It is yet another object of the present invention to provide means of laser energy to be absorbed by the selected zonules area which is either πch in collagen or a dye can be in_jected to enhance its absorption of laser energy It is yet another object of the present invention to provide a laser system which is portable, compact and easy to be integrated with a slip lamp

SUMMARY OF TIIE INVENTION The system proposed in the present invention consists of a laser which is focused to the human zonules, where it will provoke a thermal contraction It is attached to a slit lamp and shot through an ophthalmic gonio lens, aimed at the equatorial zonules and aided by a visible aiming laser that assists in focusing in the precise location The laser has the characteπstic of partial water absorption , not needing a chromophore (pigment) in order to produce a localized increase in temperature at the laser focal point The increase in temperature in the beam pathway, due to partial water absorption , is far less than that obtained at the focal point due to the cone shape of the beam , which favors dissipation In the present invention, the desire is to heat selected areas of πch in collagen tissue to shrinkage levels, but without damage or destruction of either the target or surrounding tissues The thermal shrinkage of the selected zonules area of the eye will cause the zonules to change its shape, decreasing its length, and reverse presbyopia To achieve the proposed selected thermal shrinkage of the zonules and increase the accominondation of presbyopia patient, the system design must meet the following requirements (1) the absorption of the laser beam in its propagation path inside the eye is optimal, not too high to cause damage other than the selected area to be shπnkaged, but high enough to cause the thermal effect on the selected area, (2) the laser beam shall be focused and enter the eye in a cone shape having the focal point near the selected target, and (3) the thermal shrinkage of the selected area shall cause the lens to change its shape or length such that the patient's eye can accommodate to see both far and near We note that absorption of laser energy at the selected zonules area can be achieved either by zonules πched-collagen which absorbs infrared laser energy or by injection a visible dye to absorb visible laser energy The zonules are considered to be relatively inert in its steady state, and while thermally induced contraction occurs by the process of this invention, temperatures are bellow the thermal traumatic or inflammatory thresholds In absence of trauma, the dimensional collagen reconfiguration is believed to exhibit long-'erm stability

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is a horizontal sectional view of an eye FIG 2 is a block diagram of the apparatus of the invention, where (A) shows the overall structure and surgeon's view and (B) shows the beam path inside the gonio lens FIG 3 is a hoπzontal sectional view of an eye and the laser treated area of zonnular ligaments FIG 4 shows laser parameters and the temperature increase versus laser beam position in the eye FIG 5 is a schematic cross-sectional view of propagation of the laser in the eye with focused area in zonnular ligaments

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT This invention is directed to tissue shrinkage by the use of a laser coherent energy in the wavelength range of about (0 5 - 0 7) microns when a dye is used or (0 9-1 3) microns when no dye is used based on the spectral-absorption coefficients of these wavelengths (about 0 2 to 1 0 reverse cm), without damage or destruction of adjacent tissue The thermal shrinkage of the selected area of the eye will cause the zonules to change its shape or length, and reverse presbyopia We note that absorption of laser energy at the selected zonules area can be achieved either by zonules πched-collagen which absorbs infrared laser energy or by miction a visible dye to absorb visible lasers For examples, a green dye will absorb lasers with wavelength about 530 nm and a red dye will absorb laser energy with wavelength about 630 nm To define the selected areas of the eye to be treated by a laser, we show, in FIG 1, a hoπzontal section of an eye 10 having roughly a spherical and transparent cornea 11 at the central portion The eye's ins 12 is positioned between the cornea 11 and lens 15 to divide the space forward of the lens into an anterior chamber 16 and posteπor chamli.r 17 filled with watery aqueous humor The crystalline lens 15 is supported by zonnular ligaments 14 and connected to the ciliary body 13 The zonnular ligaments and the ciliary body muscle regulates the thickness (shape) of the lens by accommodation and enable the eye to focus on objects at various ranges The space behind the lens is filled with a clear gel-like body 17 called vitreous humor In the pπor arts of the inventor J T Lin, Pat US Pat 6,258,082, 6,263,879 and PCT/US01/24618, they proposed to use non-thermal lasers to remove a portion of the scleral tissue over the ciliary body 13 to increase the accommodation of a presbyopic patients In the present invention, we propose thermal lasers to selectively deliver its thermal energy at the zonules area 14, where laser energy (with infrared or visible wavelength) may be absorbed either by the zonules collagen or by the area which is injected by visible dye When there is no dye is used, the desire of the present patent is to use near infrared lasers to heat selected areas specially rich in collagen tissue to a shrinkage level, but without damage or destruction of either the target or surrounding tissues Visible lasers will be preferred when visible dyes are injected to the zonules area Preferably, the optical-delivery-system laser is integrated with a slip lamp to enable the surgeon to define the target area As shown in FIG 2A, the system consists of a laser system 21 having a wavelength 22 and reflected by a mirror 23 and coupled by a gomo lens 24 to the patient's eye 25 Patient's eye and the laser beam path is viewed by a surgeon through a slip lamp 26 The laser system is computer controlled for laser energy or power level and the illuminating ϋme tπggered by a footswitch 27 FIG 2B shows the detail of a gonio lens 24 having a reflection mirror 25 to deliver the focused laser beam 22 to the selected target area at a predefined spot size and energy level A commercially available gonio lens will typically have three pieces of reflecting mirrors at different angles In addition, the laser may be delivered to the targeted area in a circular pattern, at the lens equator area, by rotating the gonio lens FIG 3 shows the position of the focused laser at targeted area by selection of the reflecting gonio lens angle The preferred goruo angle varies with eye anatomy and primary position of the mirror A wide papillary dilation is mandatory for perfect visualization and treatment of the zonules The proposed gonio lens angle is about (50-70) degTees in order to reach the zonules area It is important to have the ins widely open when applying the gonio lens The research underlying this invention includes experiments with pig's eyes, propagation of a focused infrared diode laser in water and laser beam reflected by a gonio lens to a target tissue The significant feature is that desired peak temperatures are confined to the selected area of the zonnular ligaments such that corneal tissue, anteπor chamber and ciliary body will not be damaged by the cone-shape focused laser which has a larger spot size or much lower fluency in these non- target areas Lens equator may receive heat enough to form a punctiform cataract, that does not affect vision This cataract formation may be caused by insufficient pupilary dilation Another pig's eye study involved with the injection of visible dyes into the zonules area such that visible lasers energy can be "selectively" absorbed only by the dyed area whereas the remaining areas are highly transparent to the visible laser For the situation that there is no dye is injected, the proposed selective laser effect requires the laser beam to enter the eye in a cone-shape with an angle large enough to localize the laser fluency at the target area FIG 4 shows the schematic of the concept requirement for laser fluency (F), laser beam spot diameter (R), laser energy (E) and the temperature increase (T) of the eye at various position of the laser beam path By focusing the laser beam at the target area (shown by dotted vertical line), we expect the laser spot size (R) is minimum at the focal point and hence the fluency (F) and the temperature increase (T) have a peak value at the target area The laser energy (E) is exponentially decreased according to Beer's law However, the absorption of the beam path prior to the target area can not be too high, typically less than about 50%, in order to achieve enough temperature increase at the target area while keeping the adjacent tissues unheated or minimum heated The curves of FIG 4 are theoretically predicted by the following relationships among these parameters F is proportional to the square of R, T is pioportional to F and laser absoφtion coefficient, E is inverse proportional to the exponential of R Therefore when the laser beam is focused into a weakly absorbing medium we shall expect the "narrow" peak of temperature increase (T) at the focused target area which in turn avoids the damage of other non-focused areas For the situation with injected dye, laser focusing in a cone-shape to a small area in the zonules is not as cπtical as that of without dye, because the laser energy will be absorbed mainly by the area which is injected with visible dye Collimated or slightly focused laser may be used in this situation with dye The dye shall be injected to the area of the zonules and laser energy will be absorbed by the dye only in the area where laser beam spot covers For examples, a green (red) dye shall be strongly absorbed by a green (red) laser The visible lasers may be one of the commercially available diode-pumped green laser (at 532 nm), red argon laser or He-Ne laser or red diode laser (630-670 nm) FIG 5 shows the focused laser beam 22 propagating in the eye with the targeted area indicated by a circle, where the target area 14 is the zonules This figure shall be compared to FIG 3 for a more clear view of the eye position and the laser beam path It is critical that the laser beam 22 will not cause thermal damage at the non-focused areas including the cornea 11, the anterior chamber 16, the lens body 15, and the posteπor chamber 17 The laser application patterns at the target area of zonules may be achieved by rotating the gonio lens The treatment method is not limited to application of shrinking heating in pattern of circular dots and in circle πng It is also optically possible to apply the shrinkage energy as a narrow line, or as a pattern of lines forming a rectangle or other non-specified shapes Depending on the selected energy pattern and the spot size, the applied average-power per "shot" is typically in the range of about (0 1-2 0) watts One of the key objectives of this invention is to achieve a shrinkage-producing temperature elevation of at about (15-50) degree-C in the target area while preventing destructive temperature increases in the adjacent areas This goal is achieved by use of the recommended coherent wavelengths (and associated absorption coefficients) at moderate average power of about (0 2 - 2 0) watts on the zonules The selective laser may be operated in a burst or pulse mode, or gated CW mode with a width in the range of (0 1-2 0) seconds It is also within the scope of this invention to apply multiple shots of temperature- elevating energy to each tissue zone in which shrinkage is to be effected For example, two or three energy pulses (each of about 10-50 milliseconds duration) may be applied to a single zone, with short-duration interpuise separation of about (100-500) milliseconds While the invention has been shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes and vaπations in form and detail may be made therein without departing from the spirit, scope and teaching to the invention Accordingly, threshold and apparatus, the ophthalmic applications herein disclosed are to be considered merely as illustrative and the invention is to be limited only as set forth in the claims

Claims

Lin & Martinz (Claims)

CLAIMS: We claim 1 An apparatus of correcting presbyopia by thermal contracting the zonules of a human eyeball compπsing (a) a laser beam (21) having a predetermined wavelength (22), (b) a gonio lens (24) to deliver said laser beam (21) to a predetermined area of zonules (14) 2 An apparatus as claimed in claim 1, in which said laser beam is a solid state laser having a wavelength of about (0 5 - 0 7) microns and about (0 9 - 1 3) microns 3 An apparatus as claimed in claim 1, in which said laser beam (21) is a semiconductor diode laser having a wavelength of about (0 9 - 1 3) microns 4 An apparatus as claimed in claim 1, in which said laser beam (21) is a visible gas laser having a wavelength of about (0 5 - 0 7) microns 5 An apparatus as claimed in claim 1, in which said zonules (14) absorbs laser energy through collagen 6 An apparatus as claimed in claim 1, in which said zonules (14) absorbs laser energy through injected visible dye 7 An apparatus as claimed in claim 6, in which said zonules (14) absorbs energy from a visible laser about (500 - 680) nm through injected visible dye 8 An apparatus as claimed in claim 6, in which said zonules (14) absorbs energy from a green laser (about 530 nm) through injected visible dye 9 An apparatus as claimed in claim 6, in which said zonules (14) absorbs energy from a red laser (about 650 nm) through injected visible dye 10 An apparatus as claimed in claim 1, which the zonules tissue (14) is heated by said laser beam (21) with a temperature increase of about ( 15-50) degree-C 11 An apparatus as claimed in claim 1, in which said gonio lens(24) consists of at least one reflection mirror with an angle of about (50-70) degrees 12 An apparatus as claimed in claim 1, in which said gonio lens(24) is rotated to generate (he desired thermal patterns on said zonules (14) 13 An apparatus as claimed in claim 12, in which the thermal pattern on said zonules (14) is circular dots, rings or non-specified pattern