« PreviousContinue »
United States Patent  [ii] Patent Number: 4,580,559
L'Esperance  Date of Patent: Apr. 8, 1986
L'Esperance, "Chapter 2-Laser Sources and Ocular
Effects", Ophthalmic Lasers, 2nd Ed., C. V. Mosby Co.,
St. Louis, 1983, pp. 8-27.
Liben et al., "An Argon Laser Photocoagulator", APL
Technical Digest, vol. 11, No. 3, (Jan.-Feb. 1972), pp.
Taboada et al., "Response of the Corneal Epitheuum to KrF Excimer Laser Pulses", Health Physics, v. 40, May 1981, pp. 677-683.
Primary Examiner—John Doll
Assistant Examiner—Lance Johnson
Attorney, Agent, or Firm—Hopgood, Calimafde, Kalil,
Blaustein & Judlowe
In a preferred embodiment, a portable ophthalmoscope having low-power telescope elements and having an internal source of viewed-field illumination, relies on a patient's focusing properties to inspect the fundus of the eye. A laser-beam source is flexibly coupled to the patient end of the ophthalmoscope viewing axis and, after optical expansion and collimation, is folded into coincidence with the ophthalmoscope axis. A dichroic (filter) is the mirror via which the folding takes place, the filter being selected for a very narrowly limited spectral band of great attenuation of radiation at the characteristic wavelength of the involved laser, the latter having been selected for its photocoagulating and/or photoablating action on locally afflicted tissues of the retinal, choroid and/or other internal regions of the eye.
19 Claims, 7 Drawing Figures
U.S. Patent Apr. 8,1986 Sheet 1 of2 4,580,559
U.S. Patent Apr. 8,1986 Sheet2 of2 4,580,559
INDIRECT OPHTHALMOSCOPIC PHOTOCOAGULATION DELIVERY SYSTEM FOR RETINAL SURGERY
BACKGROUND OF THE INVENTION
The invention relates to laser surgery and in particular to apparatus which is sufficiently portable to enable manual manipulation of laser radiation in the performance of a surgical operation at a predetermined point 10 or points in the choroid, retina or other internal areas of an afflicted eye.
Laser surgery to date within the eye has involved relatively bulky apparatus wherein a slit lamp is the surgeon's means of observing the fundus of the patient's eye, and the output of a laser is so folded onto the axis of slit-lamp observation as to focus a desired laser-beam spot at the fundus. This necessarily involves use of the focusing power of the eye, and a lens system in external contact with the cornea is employed to correct astigma- 20 tic and other refractive errors, so as to control fidelity and size of the laser-beam spot at the fundus. With such apparatus, the slit lamp is desk-mounted and the patient must sit upright, effectively clamping himself to the chin rest of the slit lamp, to assure his immobility. The 25 slit lamp has certain degrees of aspect manipulation by the surgeon, and an auxiliary light source, such as the attenuated output of helium-neon laser is spliced into a collimated part of the laser-beam optical system (prior to folding into slit-lamp viewing axis), to provide a 30 viewable spot which is the spot size of the laser beam relied upon for surgery; such an auxiliary light source and splicing are described in my copending application, Ser. No. 617,931, filed June 6, 1984.
Laser surgery to date within the eye has involved 35 relatively bulky ruby, argon, krypton, neodymiumYAG, and organic dye lasers which, with conversion of light to heat energy, produce a thermal rise in tissue temperature sufficient to create a photocoagulation or coagulum. The pulsed neodymium-YAG laser, equally 40 bulky, produces a moderate output power and short exposure which create high power densities; and the part of a body to be operated upon must be precisely positioned for the particular desired operation. Radiation wavelengths of the aforementioned lasers are in the 45 visible or near-infrared portions of the spectrum and therefore local coagulation, vaporization, or disruption of tissue is a necessary consequent of the exposure. Careful alignment and assured fixation of the patient's eye are required, for each laser exposure. When the 50 infirmity requires several exposures, as at different locations on the retina, the procedure is cumbersome and time-consuming, requiring great patient cooperation, and the apparatus is very expensive.
In my copending application Ser. No. 552,983, filed 55 Nov. 17, 1983,1 disclose laser apparatus and techniques for ophthalmological surgery wherein selective ablation of body cells is achieved by photodecomposition, without coagulation or vaporization, using radiation in near end and far portions of the ultraviolet end of the 60 spectrum; and in my copending applications, Ser. No. 571,827, filed Jan. 19, 1984 and Ser. No. 617,931, filed June 6, 1984, I disclose further such apparatus having ophthalmological application, the device of Ser. No. 571,827 being a pencil-like manipulable tool with flexi- 65 ble optical-fiber cable connection to a local source of laser radiation, and the device of Ser. No. 617,931 being a scanning laser apparatus for non-invasively removing
a cataractous lens. Reference is made to said applications for more complete discussion.
BRIEF STATEMENT OF THE INVENTION
It is an object of the invention to provide improved laser apparatus for surgically treating the choroid, retina, or other internal structures of the eye.
A specific object is to meet the above object with a light-weight portable apparatus wherein an illuminated field of view as of the retina, is continuously viewable, with a viewed indication of the size and instantaneous location at which photocoagulating laser radiation can be made to impinge, as the surgeon may determine and control.
Another specific object is to provide such apparatus with the ability to non-invasively operate and to view the progress of a photocoagulating operation upon a precisely observed point or points of a given retina.
It is also an object to provide the surgeon with easily adjusted means whereby he can view his adjustment of the spot size, which will be the laser spot size, within his field of observation.
A further specific object is to provide such laser-surgery capability as an add-on feature of a conventional indirect ophthalmoscope.
It is a general object to meet the above objects with essentially simple structure, featuring precision and ease of use.
In a preferred embodiment, the invention achieves these objects using an indirect ophthalmoscope having a low-power afocal telescope which relies on optical properties of the patient's focusing ability to enable inspection of the fundus of the eye, an internal light source of the ophthalmoscope being projected along the telescope axis to illuminate a field of view within which an operation is to be performed. Fixedly carried by the telescope is the output end of an optical-fiber cable providing flexible connection to the output of a local laser-beam source, and a beam-splitter (preferably a dichroic mirror) in conjunction with beam-shaping optical elements folds laser energy precisely onto the telescope axis. The observed field of view displays a "center" indicium whereby the surgeon can know where the laser spot will impinge the retina within the observed field, once the surgeon decides to trigger the release of laser energy, and the surgeon can safely observe the progress of a photocoagulating operation upon his selected spot or spots in the fundus.
The invention will be illustratively described in detail, in conjunction with the accompanying drawings, in which:
FIG. 1 is a simplified and somewhat schematic view of a photocogulation delivery system of the invention; FIG. 2 is a plan view of a part in the system of FIG.
FIG. 2A is a simplified fragmentary diagram to illustrate a shutter mechanism in the system of FIG. 1;
FIGS. 3 and 4 are diagrams to illustrate field of viewing a retina in use of the system of FIG. 1, FIG. 4 involving a slight modification from FIG. 3; and
FIGS. 5 and 6 are views similar to FIG. 1 to illustrate other embodiments.
The photocoagulation delivery system of FIG. 1 comprises a light-weight portable indirect ophthalmoscope or afocal telescope having a viewing axis 10