CA2121036A1 - Improved sectioning device for lamellar surgery - Google Patents
Improved sectioning device for lamellar surgeryInfo
- Publication number
- CA2121036A1 CA2121036A1 CA002121036A CA2121036A CA2121036A1 CA 2121036 A1 CA2121036 A1 CA 2121036A1 CA 002121036 A CA002121036 A CA 002121036A CA 2121036 A CA2121036 A CA 2121036A CA 2121036 A1 CA2121036 A1 CA 2121036A1
- Authority
- CA
- Canada
- Prior art keywords
- keratome
- blade
- major surface
- set forth
- adjustable plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
- A61F9/007—Methods or devices for eye surgery
- A61F9/013—Instruments for compensation of ocular refraction ; Instruments for use in cornea removal, for reshaping or performing incisions in the cornea
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
- A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
- A61B2090/3937—Visible markers
Abstract
A keratome is machined from a single block of material to form front and back portions that cannot become distorted during use.
The blade is held at a reduced angle and a surface defining a chamber for receiving the slice intersects the blade at a tangent. The adjustable plate overlaps the blade a predetermined amount. The lower edge of the plate, adjacent the blade, is shaped for an improved cut, as is the blade itself. The suction ring is laser welded to avoid distorsion of the channel for the keratome and an applanator is shaped to prevent relative motion of the applanator along the channel.
The blade is held at a reduced angle and a surface defining a chamber for receiving the slice intersects the blade at a tangent. The adjustable plate overlaps the blade a predetermined amount. The lower edge of the plate, adjacent the blade, is shaped for an improved cut, as is the blade itself. The suction ring is laser welded to avoid distorsion of the channel for the keratome and an applanator is shaped to prevent relative motion of the applanator along the channel.
Description
W~93/06783 : ` PCT/US92/&8571 ';IMPROVED SECTIONING DEV~CE FOR LA~I~LLAP~ S~RGERY
Backyround of the Inver.tion This invention relates to surgical apparatus for surgically removing thin sections of tissue anu, in particular, to a keratome for use in ophthalmological procedures.
The eye is a compound optic comprising a cornea (the lC transparent, outer ~ayer~ and a lens. Approx-mately seventy percent of the focusing of light in the eye 1s perfor~ed by the cc.rnea; viz. approxi~ately forty-two diopters. (A
diopter is a standard unit of measurement and is the reciprocal of the focal length of a le~s in meters.) The remaind~r, about eighteen diopters, is performed by the ~ens of the eye. In the average total re4raction cf siXty diopte~ s, ca variation of less than five diopters is ccnsidered normal~variation among a population~ An erxor o~
mor~ than f ive: :diopters is considered pathological.
~0 Dr. Jcse Barraquer~of Bogota, Columbia, suggested in 194n th~t many problems with~vision c3uld be corrected by surgica'.y changing~the shape of the cornea; ViZ. its cur~ature. Dr. Barraquer first published in 196~ the results of a procedure to correct myopi~ (ne.lrsightedness).
25~ ~ The prQcedure took a~ thin sec~ion from the front of the ~: :
cornea, centered above the pupil. lle froze ~he section, - shaped it wît:h a~ cryogenic latne, thawed ît, and re-attac~lPd it to th~ ey~. The equipmen~ for performing this procedur~
is large, e~pensi~e an~ not entirely sati;raotGr-. In W~93/06783 2 1 2 1 0 3 ~ PCT/US92/0~57~
general, progress in this area has been limited by lack OL
suitable equipment; in particular, by a lack of equipment for removing smooth, round tissue o~ the desired thickness from a cornea and, at the same time, leave a smooth bed for the tissue to adhere to when it is replaced.
~he tool used for making corneal slices is known as a keratome. Some keratomes resemble a tiny block plane havin~
an overall length of about three centimeters. Unlike a plane, the blade in the keratome oscillates from side to side at high speed to slice the tissue.
FIG. 1 illustrates a keratome of the prior art. The keratome comprises an elongated body 11 having a slanted surface at one end thereof for receiving blade 12. Cam 14 engages a hole in blade 12 to drive blade 12 from side to si~e (into and out of the plane of the drawing). Apparatus (not shown) extending through channel 16 in head 18 drives coupling mem~er 14. Suitable drive means can b~ electrical or pneumatic. H~ad 18 is held in place by co~lar 21, which is threaded on to head 18 and a portion of body ll. Head 1 and body 11 together form a slot for containing blade 12.
The front~end of the keratome has a vertically movable plate : 23. The di~ference in hei~ht ~etween the edge of movable plate 23 and ~he edge of blade 12 determines the thickness of the sectio~ removed from the cornea. ~djustment means 24 pro~ides a very small movement of plate 23, which is biased by spring 25 to avoid bacXlash.
~As used herein, terms implying direction are for con~enience in referring to the drawings, e.g. "front,"
"back," "vertical," otherwise the terms are of no W093/06783 ~ ; PCT/US92/08571 ;
significance.) 2121036 In use, the plate is adjusted to an appropriate height.
A tool known as an suction ring is applied ~o the front of the eye, centexed over the iris. Suction rings are made in dif~erent thicknesses to vary the diameter of the section removed from the cornea. When placed over ~he eye, the suction ring locates, confines, and sligh~ly bulges the cornea, by raising the interocular pressure, to flatten the cornea against the plate for slicing by the keratome. The suction ring has a dovetail fitting for receiving the lower edges of the keratome, which has a corresponding dovekail shape.
The power is applied to the keratome, which causes the blade to oscillate at ten to twenty thousand cycles per minute. The keratome is slid through thé dovetail in the suction ring, causing a section OL tissue of the cornea to be removed and pass into interior chamber 27 of the keratome. The surge~n then recovers the tissue from the keratome ar;d later~replaces it on the cornea.
FIG. 2 is a simplified illustration of a cross-secti~n of a portion of a human eye. Eye 30 comprises lens 31 separ~ted~from cornea 32~by anterior space 33. In the centràl region above l~ns 31, cornea 32 has a thickness of , about five hundred twenty microns which increases toward the conjunc~i~a (toward the sides).
~The cornea itself actually com~rises fi~e layers, the outer three of which are illustrated in FI~. 3. The ou~ermost layer is known as the epithelium layer, denoted as layer 35 in FIG. 3, an~ îs fifty to ninety microns thick.
WO g3/116783 21210 3 G PCI/US92/08571 The Bowman layer, denoted as layer 3 6, separates the epithF~lium from the substantia propria Ol: stroma, layer 37.
The Bowman layer is about twelve microns thick. Layer 37 comprises most of the thickness of the cornea, four hundred to ~our hundred arld f if ty microns.
During keratomileusis in-situ for myopia, two sections are removed from the cornea. A first section is cut as illustrated in FIG. 2, yielding disk 38. The disk is not flat because the cornea is flattened somewhat prior to the cut being made. After the cut, the disk returns to a three dimensional shape. Bed 39 is the outer surface of the remaining cornea. A second cut is made to remove a second disk~ Disc 38 i5 then re-att~ched. (Disk 3~ contains the cr?~!tical Bowman layer). The effect is to flatten or reduce the curvature of the cornea, ~orrecting nearsightedness.
The requirement for smooth cuts with no rough edges nor bed ~is compounded when two~cuts are made. A smooth bed is especially difficult to~leave after the second cut because of the structure of the cornea. Specifically, the epithelium or outer layer ~of~the cornea comprises lamellar ~thin,~plate-}ike~oells 41 (FIG. 3) on its outer surface and columnar cells~4Z~ on its inner~surface. The colu~nar cells are more pliabla and tend to yield rather than be cut i, . .
; by a blade. Also,~with the somewhat tougher outer layer ~25~ removed, the softer,~fibrous tissue in layer 37 i5 more difficult ko cu~ smoothly . Prior to the present invention, no keratomé has been available which is capable of making perfectly round, smooth, second cuts for this procedure.
The risk of having rough edges and an irregular W093/06783 ; ~ PCT/USg2tO8571 periphery restricts the range of thicknesses of the cuts that can be made and, hence, the range of corrections that can ~e obtained because the cuts must be relati~ely thick.
This makes the procedure useful only for severely myopic S patients; e.g. where the desired correction is eight diopters or more. It is highly desirable to be able to cut thin, precise disks, which will enable the su~geon to use the procedure for correction of low and mid-myopia (two to three diopters and four to eight diopters). Further, keratomes of the prior art leave undesirable micrcscopic ridges ~nd valleys across the surface of the cornea, even in the hands of highly skilled surgeons.
Whether one disk or two disks are cut, a deficiency with keratomes of the prior art is the in`consistency ~f the cuts; i.e. a given combination of keratome setting and suction ring did not yield consistent, ~redictable results.
Instead, the shapes and thi~knesses of the disks varied and the remaining beds on corneas were rough. Since the correction is relative to the thickness of the cut and the smoothness of the bed, a different instrument is necessary.
In view of the foregoing, it is therefore an object of the invention to proYide a surgical tool for obtaining accurate, smooth cuts of delicate tissue.
Another object of the invention is to provide an improved keratome for enabling one to make cuts having smooth edges and~surfaces.
A f~rther ob~ect of the invention is to provide an improved keratome capable of consistently cuttin~ smooth, round disks of the diameter and thickness desired by the W093/06783 2 1 210 3 6 PCT/USg2/08571 surgeon to correct a greater range of myopia.
Another object of the invention is to provide a keratome capable of making smooth, round, cuts on a human cornea.
A further object of the present invention is to provide a keratome that can produce consistent results from device to device.
SUMMARY OF INVENTION
The foregoing objec~s are achie~ed in the invention wherein the keratome holds the blade at a reduced angle and wherein braces reinforce the connection of the front and bacX portions of the kPratome ~ody so that th~ body is rigid throughout its length. The blade is sharpened to a parti~ular bevel anglP and honed at two diff~rent an~les to produce a superior edge. The interior chamber of the keratome body is~shaped for~receiving the tissue being cut and the bladè i~ covered with an extension for guiding the tissue through the~keratome body:. In addition, the blade is : held within a slot machined to an extremely fine tolerance : ~ to eliminate vertic~l;:movement of the blade when it is cutting. The pressure plate is trapezoidal to assure that it can be assem~led to ~he body in only one ! wa~. The ~25 ~ construction af~the~plate insures that it~stays parallel with the cutting edge of the blade. The edge of the blade .
: is oriented with respect to the adjacent edge of the ~ , : pressure plate to insure a c~lean cut. In addition, the pressure plate is manufactured and mounted in a way which W093~06783 2 1 2 1 0 3 6 i I ` PCT/USg2/08S71 assures uniform application of pressure across its entire surface. In accordance with another aspect of the present invention, the suc~ion rings are made by laser welding the stem to the ring and then forming the dovetail in the riny.
In accordance with another aspect ~f the invention, the applanat~rs have a diameter greater than the ring to overlap the ri.~g on two sidPs, thereby precluding any mo~ement of the applanator during use.
A more complete understanding of the present invention can be obtained by considering the following detailed description with the accompanying drawings in which:
FIG. 1 illustrates a keratome of the prior art.
FIG. 2 illustrates a cross-section of a portion of a human eye.
FIG. 3 illustrates a detail of the structure of a human cornea.
FIG~ 4 illustrates a suction ring and an end view of a keratoms in accordanc2 with the invention.
FIG. 5 illustrates a side view of a keratome in accordance with the invention.
FIG. 6 illustrates the movable plate used in the Xeratome of the~invention.
FIG. 7 illustrates a spring means for biasing the movable plate in accordance with the'invention.
FIG. 8 illustrates a blade in accordance with the , ; invention. ~
FIG. 9 illustrates a drive cam in accordance with the invention.
FIG. 10 illustrates the drive shaft for moving the 'W093/06783 2 1 2 1 0 3 6 P~T/US92/08~71 ,~
cutting blade. . ' FIG. 11 illustrates a detail of the alignment of the blade with the movable plate in accordance with the invention.
FIG. 12 illustrates an applanator in accordance with the invention.
FIG. 13 illustrates the markings on the upper inner sur~ace ~he applanator.
DETAILED DESCRIPTION
Referring to FIGS~ 4 and 5, the main frame of keratome 40 is made from a single block of stainless steel having do~etails 41 and 42 formed in the lower edges thereof.
Threaded connection 43 is at the rear of keratome 40 and ha~
bore 44 cut therein. A drive shaft fits into bore 44.
Connection 43 attaches keratome 40 to suitable dri~e apparatus, not shown and well known per se in the art, for example for dental drills and keratomes of the prior art.
Chambers 46 and 47 extend from side to side through keratome 40. Chamber 46 is partially defined by curved surface 48 which extends over substantially the whole length of the blade, except for an exposed portion in region 49.
The blade is located in slot 51 which extends from side to Z5 si~e and connects chambers 4~ and 47. Chamber ~7 receives the drive cam which moves the blade from side to side. Bore 4 c:onnects with chamber 4 7 .
Cha~ber 4 6 does not extend to the top of keratome 4 0, forming braces 52 on each side of the top which interconnect the front and rear pcrtions of keratome 40, grea~ly stiffening it to prevent any distortion of the original configuration, which would adversely affect the precision of the cut. Braces 52, as illustrated in FIG. 4, allows access to chamber 46 through the top of keratome 40.
A~terna~ively, braces 52 could be, a surface extending from side to side, enclosing the top of chamber 46.
The front por~ion of keratome 40 defines chamber 53 ~or receiving the movable plate and bias spring, as described in conjunction with FIGS. 6 and 7. Bore 55 passes through the upper surface of chamb~r 53 and receives column 62 (FIG. 6j.
Knob 56 contains a screw with extends through bore 55 to engage threaded bore 63.
In one embodiment of the inYention, the length of keratome 40, not including connector 43, was l.350 inches.
The radius of curvature of surface 48 was 0.~25 inches. The radius is not critical although it is preferably large with respect to the dimensions of chamber 46. What is important is that the blade be tangential or nearly tangential to surfaGe 48:at their intersection, point 58. This ~ relationship, curved~surface 48, and the volume of chamber :: . 46 as~ure that the corneal disk will not fold or ~ind and is easily removed fro= the keratoma by the surgeon.
Chamber 47 is preferably machined to dimensions eq~al to the dimensions of the cam, plus .0005 inch~ This precludes unwanted movement of the cam and assures steady driving of the blade. Similarly~ slot 51 is prefera~ly machined to the thickness of the blade, plus ~0005 inch.
This prevents the blade from fluttering as it vscillates, ~s W093/06783 ~ I O ~ 6 PCTlUS92/08571 seen in kerato~es of the prior art. Since keratome 40 is machined from a single block of steel, the height of slot 51 can ~e precisely controlled, in contrast to the two piece assem~ly of the prior art.
Slot 51 is angled with respect to the bottom of the keratome. In the prior art, this anyle was tw~nty~six degrees or more, In the present in~ention, it has been found that a blade angle of less than fifteen degrees is required. A preferred embodiment of thé present invention uses an angle of nine degrees relati~e to the bottom of the keratome. It is belie~ed that this causes the blade to slice rather than scrape the~cornea.
FI~. 6 is a top view of the adjustable p~ate in accordance with the invention. Plate 61 is attached to column 62 having threaded bore 63 therein. Plate 61 preferably has a trapezoidal shape to permit assembly in only one direction. Chamber 53 also has a orresponding trapezoidal cross-section in a plane parallel to the bottom ~ of keratome 40. ~ Edges 64 and 65 are parallel. Edges 66 ar.d 67 are not parallel~::but draw closer~to one another toward edge 6S. The~amount of taper is a matter of design. A
taper of 0.0 4 inch per ~inch has been found suitable. Edge 65 is located adjacent the blade. ~olumn 62 is of :: sufficient diameter~, e.g. 0.18 inches, to assure tha~ plate ~ 61 can be calibrated :to~the desired position and not change duxing use. Bore~63 preferably has a fine thread to allow small adjustments to be made:in the space between tbe plate : ~ and the blade,~because that space primarily determines the thickness of the cut. Sixty threads per inch has been found 1~
W~93/06783 ~ P~T/US92/0~571.
suitable. 21 2 i 0 3 6 The adj~stable plate is preferably made from a single piece of stainless steel. This assures stability between the bolt and the plate itself. The bottom surface of plate 61 is ground ~lat to within .0005 inches and then lapped.
The flatn~ss assures an accurate.cut and the l~pping assures that the cornea will not be scratched or otherwise damaged by the tool. In addition, the lower portion of edge 65 is beveled and has a radius, as further described in connection with FIG. ll.
YIG. 7 illustrates spring means used to bias the adjustable plate. Specifically, ~pring means 70 comprises resi~ient, annular disks 71 and 72 having oppositely curved portions 73 and 74. In addition, a part of the pe~imeter of each disk is flattened to assure that the disks cannot r~tate relative to one another during us~. Flats 75, 76, 77 and 78 are para1lel to the inner side walls of chamber 53 and are slightly spaced therefrom. ~he upper surface of disk 71 rests on the inside of the upper surface of chamber 53. The lower surface of disk 72 res~s on the upper surface of adjustable pIate 61. Bolt 62 fits within the opening in the center of dis~s 71 and 72. ~hile onIy two disks are shown, more disks can be used. In addition J d~pending upon the height of chamber 53, flat annular disks can be added ` 25 between the curved resilient disks. It is preferred that the range of movement of plate 61 be limited so that the maximum depth of cut does not exceed the thickness of the : average cornea, five hundred and twenty microns.
FIG. 8 illustrates a blade in ccordance with the W093/06783 212 I 0 3 6 PCT/US92/0~$71 inventionr The blade cGmprises surgical steel cut to the ~
width of k~ratome 40. ~dge 82 is sharpened as described in conjunction with FIG. 11. Opposite edge 82 is keyway 83 for receiving a key from the drive cam illustrated in ~IG. 9.
Blade 81 typically has a thickness of 0.00~ in.
Cam g0 is a rectangular block ha~ing the same width as the keratome. Recess 91 is ~ormed in a broad face, forming shoulders 92 and 93. Slot 94 i5 formed in recess 91. Key 95 is formed on the bottom surface of cam 90 and has a shape corresponding to keyway 83, into which it fits. It is preferred that the recess and slot not extend into the bottom surface adjacent key 9S to assure a full bearing surface for the cam.
. In use, key 95 is inserted into keyway 83 in blade 81 1~ and the two together slid sideways into the keratome block illustrated in FIG. S. The slotted major face of cam 90 must face connector 43 to accept the drive shaft.
FIG. ~0 il~ustrates a portion of the drive mechanism, specifically the drive shaft and pin. The mechanis~ for : 20 turning the driveshaft is well ~own per se in the art.
DriYe shaft 96 ends in a flat face having pin 98 eccentrically mounted thereon. .The distance between the axis 97 of shaft 96 and axis ~9 of p.~n 98 is the stroke of : the blade. The stroke is a matter of design, but is typically 0.150 in. The :end of shaft 96 fits within recess : 91 of cam 90~ Pin 98:fits into slot 94. As drive shaft 96 rotates, the rotational motion is converted into reciprocal motion by cam 90l which drives blade Bl from side to side in keratome 40. It is pr ferred that the shaft be spring W~93/06783 2121 0 3 6 P~T~US9X/08~71 i loadsd to provide some compliance along its length while it is driving cam 90.
Because of the recess forming shoulders 92 and 93, and the f~ct that the recess does not extend through to the key, one obtains a safety advantage if the pin should break off from drive shaft g6 in that the cam and blade would be trapped within their cham~rs by the drive shaft which fits in recess 91.
FIG. 11 illustrates the relationship between the cutting edge of the blade and the corner of adjustable plate 61. The blade is preferably symmetrical about axis ~10.
The edge of blade 81 is formed by grinding at an angle of six degrees relative to axis 110 in region 111. This is followed by honing at an angle of eight degrees in region 112, which is followed by honing at an angle of eleven degrees in tip 114. This edge treatment has been found to produce a superior cutting edge for cutting a cornea.
FIG. 11 also illustr~tes the edge treatment of the underside of edge 65, which is position~d adjacen~ blade ~1.
Edge 65 preferably has a bevel 121 of twenty-seven degrees, plus or minus one degree, relztive to lower surface 120.
The bevel need not~extend the full thickness of plate 61.
In a preferred embodiment of the present invention, it occupies only the lower half of edge 65. The extent of the bevel is a matter of design. Its purpQse is to provide cleara~ce and guidance for the corneal disk coming off the blade. The bevel and~the lower surface of adjustable plate 61 should not meet at a corner or edge. Thus, the surfaces are connected by ~adius 123. The specific value of the W093/067~3 2 1 2 1 ~ 3 6 P~T/US92/08~7l-radius is a matter of design, but the radius must be there t to protec~ the outer surface of the cornea. Lower surface 120 is tangent to the radius at their intersection, a line perpendicular to the plane of the drawing, represented by point 124.
In Dr. Barra~uer's work, the k~ratome did not h~ve a adjustable plate, but a set of interchangeable, fixed plates of different thicknesses. While the plate overlapped the blade, the location of the edge of the plate relatlve to the edge of the blade was not precise. In keratomes o~ the prior art having adjustable plates, such as illustrated in FIG. 1, the blade and the plate do not ovelap: the plate can be removed with the blade in place. In short, it has not been recognized that the location o~ the edge o~ the blade relative to the edge of the plate is important, It has been found that th effectiveness of the cut depends, in part, upon the locations of the edge of blade 81 and the corner of plate 61. Specifically, optimum results are obtained if point 124 i5 located above tip 114 of blade 81; i~e. between lines 126 and 127. It is belie~ed khat locating point 124 :above tip 114 provides support for the cornea during and immediately a~ter cutting the cornea, thereby improving the smoothness of the cut, particularly at .
the end of the cut~ which has heretofore been a problem ~` 25 area. Because some overlap is good does not mean that mor~
overlap is better. It:bas also been found that greater overlap produces in~erior cuts, compared to that obtained with the pl~te prop~rly located horizontally.
Referring to FI~. 4, suction ring 140 is placed over WO 93/(~67/~3 2 1 2 1 0 3 6 1 P~r/US~2/~57l , ~..
corne~ 141~ Cir~ular opening 142 i5 located ~ver the center of the front of the eye. Suction is provided thxoug~ handle 145, which is hollow and has fitting 146 at the end thereo~
for connection to a vacuum system. ~ore 147 connects handle 145 with the interior of ring 140. The reduced pressure draws cornea 1~1 up into aperture 142, which typically has a diameter of 11.25 mm. Dovetails 41 and 42 of keratome 40 fit into corresponding dovetai's 151 and 152 in suction ri~g 140. The front of the keratome is inserted into the channel and the keratome (with the blade oscillating) slides across ring 140, cutting a disk from the cornea. The thickness of the disk is regulated by the setting of adjustablé plate 61 before the operation.
Xn the prior art, the rin~ was machined and the handle attached, either by welding or by screwing the threaded end of the h~ndle into a threaded bore in the ring. The screw fitting was not a reliable connectlon, weak and prone to leakage. Welding the handle distorted the geometry of the ring so that the dovetail joints did not function smoothly.
In accord~nce with another aspect of the invention, the ring is machined, except for the dovetails. The handle is : attached by laser welding, which heats the body of the ring very little, and then the dovetails are formed. ~he result is a precise, smooth joint between the keratome and the ring.
The diameter and thickness of the disk removed from the cornea depends upon the thickness of the suction ring and the depth of cut as determined by the setting ~f adjustable plate 61. Choosing the right suction ring is done with what W093/06783 PCT/VSg2/08~71 . is known as an applanator; a transparent, acryllc cyllnaer havincS a domed or spherical top to give some enlarge~ent of the viewing area. FIG. 12 illustrates an improved ~ applanator in accordance with another aspect of the ', 5 invention. Applanator 155 is of greater diameter than ring ~ 157 and has shoulder 158 formed therein for engaging the outside o~ ring 157 at each en~ of the channel. The sidewall extends down between the dovetails in ring 157, not shown in FIG~ 12. Thus, applanator 155 cannot move relative `l 10 to ring 157, thereby giving a consistent view of the cornea.
'! Flats are formed in the sides of the applanator, as in the "
prior art, with grooves for clearing the handle. In ., accordance with the invention, the grooves are dimensioned to fit closely around the handle, thereby further stakilizing the measurement and assuring that the applanator :j and ring are located accurately.
FIG. 13 illustrates the indicia marked on interisr surface 159 of applanator 155. The inner circle has a ; diameter equal to that marked on the applanator (3.5-6.5 ~l 20 mm.) and aids in centéring the applanator. The outer circle .'. has a diameter of 7.25 mm., which is the standard diameter of the first disk~ cut. The crosshairs aid in centering the ring and, in par~icular, aid in re-centering the ring for the second cut. Induced astigm~tism can occur from several causes, one of which is that the ring was not centered for the second cut. (The second cut removes a smaller diameter disk 50 the first ring must be removed and a thinner ring ~;, used for the second cut.) The kera~ome is preferably machined from a single block ~ .
WOg3/06783 21210 3 ~ PCT/US92/08~71 'o 400 series stainless steel ~y what is known per se ln Ine~
~ art as EDM (electron discharge machininy). In order to ! assure the stability of the steel, it i5 heat treated (annealed~ pri~r to cutting. The various channels, bores, S and s'ots can then be cut in a reproducible manner, in part 3 due t:o ~he stability of the material and in part due to the precision of EDM.
There is thus provided by the invention an i~,proved keratome capable of making precise cuts wherein each cut has 3 lO smooth edges and is free of ridges or valleys. Because of ; the smoothness of the cut, corrections of low and mid-myopia `'t are achievable, Having thus described the invention, it will be apparent to those of skill in the art that many , 15 modifications can ~e made withln the invention. For '~ example, while descri~ed in conjunction with a particular procedure, the use of the invention is not so limited. The ;i invention can be used wherever smooth cuts of delicate tissue are desired. Although a dovetail connection between the keratome and the suction ring has been shown and described, it~is understood that other connections providing the same function~can be used,~e.g. a bead and cove. While - described as a threaded column on the adjustable plate receiving a threaded connector from the top of the keratome, it is understood that the reverse is equally effecti~e: a threaded bolt attaohed to the plate fitting within a threaded column from the top of the keratome.
~ What is claimed is:
,i~
.~
:,
Backyround of the Inver.tion This invention relates to surgical apparatus for surgically removing thin sections of tissue anu, in particular, to a keratome for use in ophthalmological procedures.
The eye is a compound optic comprising a cornea (the lC transparent, outer ~ayer~ and a lens. Approx-mately seventy percent of the focusing of light in the eye 1s perfor~ed by the cc.rnea; viz. approxi~ately forty-two diopters. (A
diopter is a standard unit of measurement and is the reciprocal of the focal length of a le~s in meters.) The remaind~r, about eighteen diopters, is performed by the ~ens of the eye. In the average total re4raction cf siXty diopte~ s, ca variation of less than five diopters is ccnsidered normal~variation among a population~ An erxor o~
mor~ than f ive: :diopters is considered pathological.
~0 Dr. Jcse Barraquer~of Bogota, Columbia, suggested in 194n th~t many problems with~vision c3uld be corrected by surgica'.y changing~the shape of the cornea; ViZ. its cur~ature. Dr. Barraquer first published in 196~ the results of a procedure to correct myopi~ (ne.lrsightedness).
25~ ~ The prQcedure took a~ thin sec~ion from the front of the ~: :
cornea, centered above the pupil. lle froze ~he section, - shaped it wît:h a~ cryogenic latne, thawed ît, and re-attac~lPd it to th~ ey~. The equipmen~ for performing this procedur~
is large, e~pensi~e an~ not entirely sati;raotGr-. In W~93/06783 2 1 2 1 0 3 ~ PCT/US92/0~57~
general, progress in this area has been limited by lack OL
suitable equipment; in particular, by a lack of equipment for removing smooth, round tissue o~ the desired thickness from a cornea and, at the same time, leave a smooth bed for the tissue to adhere to when it is replaced.
~he tool used for making corneal slices is known as a keratome. Some keratomes resemble a tiny block plane havin~
an overall length of about three centimeters. Unlike a plane, the blade in the keratome oscillates from side to side at high speed to slice the tissue.
FIG. 1 illustrates a keratome of the prior art. The keratome comprises an elongated body 11 having a slanted surface at one end thereof for receiving blade 12. Cam 14 engages a hole in blade 12 to drive blade 12 from side to si~e (into and out of the plane of the drawing). Apparatus (not shown) extending through channel 16 in head 18 drives coupling mem~er 14. Suitable drive means can b~ electrical or pneumatic. H~ad 18 is held in place by co~lar 21, which is threaded on to head 18 and a portion of body ll. Head 1 and body 11 together form a slot for containing blade 12.
The front~end of the keratome has a vertically movable plate : 23. The di~ference in hei~ht ~etween the edge of movable plate 23 and ~he edge of blade 12 determines the thickness of the sectio~ removed from the cornea. ~djustment means 24 pro~ides a very small movement of plate 23, which is biased by spring 25 to avoid bacXlash.
~As used herein, terms implying direction are for con~enience in referring to the drawings, e.g. "front,"
"back," "vertical," otherwise the terms are of no W093/06783 ~ ; PCT/US92/08571 ;
significance.) 2121036 In use, the plate is adjusted to an appropriate height.
A tool known as an suction ring is applied ~o the front of the eye, centexed over the iris. Suction rings are made in dif~erent thicknesses to vary the diameter of the section removed from the cornea. When placed over ~he eye, the suction ring locates, confines, and sligh~ly bulges the cornea, by raising the interocular pressure, to flatten the cornea against the plate for slicing by the keratome. The suction ring has a dovetail fitting for receiving the lower edges of the keratome, which has a corresponding dovekail shape.
The power is applied to the keratome, which causes the blade to oscillate at ten to twenty thousand cycles per minute. The keratome is slid through thé dovetail in the suction ring, causing a section OL tissue of the cornea to be removed and pass into interior chamber 27 of the keratome. The surge~n then recovers the tissue from the keratome ar;d later~replaces it on the cornea.
FIG. 2 is a simplified illustration of a cross-secti~n of a portion of a human eye. Eye 30 comprises lens 31 separ~ted~from cornea 32~by anterior space 33. In the centràl region above l~ns 31, cornea 32 has a thickness of , about five hundred twenty microns which increases toward the conjunc~i~a (toward the sides).
~The cornea itself actually com~rises fi~e layers, the outer three of which are illustrated in FI~. 3. The ou~ermost layer is known as the epithelium layer, denoted as layer 35 in FIG. 3, an~ îs fifty to ninety microns thick.
WO g3/116783 21210 3 G PCI/US92/08571 The Bowman layer, denoted as layer 3 6, separates the epithF~lium from the substantia propria Ol: stroma, layer 37.
The Bowman layer is about twelve microns thick. Layer 37 comprises most of the thickness of the cornea, four hundred to ~our hundred arld f if ty microns.
During keratomileusis in-situ for myopia, two sections are removed from the cornea. A first section is cut as illustrated in FIG. 2, yielding disk 38. The disk is not flat because the cornea is flattened somewhat prior to the cut being made. After the cut, the disk returns to a three dimensional shape. Bed 39 is the outer surface of the remaining cornea. A second cut is made to remove a second disk~ Disc 38 i5 then re-att~ched. (Disk 3~ contains the cr?~!tical Bowman layer). The effect is to flatten or reduce the curvature of the cornea, ~orrecting nearsightedness.
The requirement for smooth cuts with no rough edges nor bed ~is compounded when two~cuts are made. A smooth bed is especially difficult to~leave after the second cut because of the structure of the cornea. Specifically, the epithelium or outer layer ~of~the cornea comprises lamellar ~thin,~plate-}ike~oells 41 (FIG. 3) on its outer surface and columnar cells~4Z~ on its inner~surface. The colu~nar cells are more pliabla and tend to yield rather than be cut i, . .
; by a blade. Also,~with the somewhat tougher outer layer ~25~ removed, the softer,~fibrous tissue in layer 37 i5 more difficult ko cu~ smoothly . Prior to the present invention, no keratomé has been available which is capable of making perfectly round, smooth, second cuts for this procedure.
The risk of having rough edges and an irregular W093/06783 ; ~ PCT/USg2tO8571 periphery restricts the range of thicknesses of the cuts that can be made and, hence, the range of corrections that can ~e obtained because the cuts must be relati~ely thick.
This makes the procedure useful only for severely myopic S patients; e.g. where the desired correction is eight diopters or more. It is highly desirable to be able to cut thin, precise disks, which will enable the su~geon to use the procedure for correction of low and mid-myopia (two to three diopters and four to eight diopters). Further, keratomes of the prior art leave undesirable micrcscopic ridges ~nd valleys across the surface of the cornea, even in the hands of highly skilled surgeons.
Whether one disk or two disks are cut, a deficiency with keratomes of the prior art is the in`consistency ~f the cuts; i.e. a given combination of keratome setting and suction ring did not yield consistent, ~redictable results.
Instead, the shapes and thi~knesses of the disks varied and the remaining beds on corneas were rough. Since the correction is relative to the thickness of the cut and the smoothness of the bed, a different instrument is necessary.
In view of the foregoing, it is therefore an object of the invention to proYide a surgical tool for obtaining accurate, smooth cuts of delicate tissue.
Another object of the invention is to provide an improved keratome for enabling one to make cuts having smooth edges and~surfaces.
A f~rther ob~ect of the invention is to provide an improved keratome capable of consistently cuttin~ smooth, round disks of the diameter and thickness desired by the W093/06783 2 1 210 3 6 PCT/USg2/08571 surgeon to correct a greater range of myopia.
Another object of the invention is to provide a keratome capable of making smooth, round, cuts on a human cornea.
A further object of the present invention is to provide a keratome that can produce consistent results from device to device.
SUMMARY OF INVENTION
The foregoing objec~s are achie~ed in the invention wherein the keratome holds the blade at a reduced angle and wherein braces reinforce the connection of the front and bacX portions of the kPratome ~ody so that th~ body is rigid throughout its length. The blade is sharpened to a parti~ular bevel anglP and honed at two diff~rent an~les to produce a superior edge. The interior chamber of the keratome body is~shaped for~receiving the tissue being cut and the bladè i~ covered with an extension for guiding the tissue through the~keratome body:. In addition, the blade is : held within a slot machined to an extremely fine tolerance : ~ to eliminate vertic~l;:movement of the blade when it is cutting. The pressure plate is trapezoidal to assure that it can be assem~led to ~he body in only one ! wa~. The ~25 ~ construction af~the~plate insures that it~stays parallel with the cutting edge of the blade. The edge of the blade .
: is oriented with respect to the adjacent edge of the ~ , : pressure plate to insure a c~lean cut. In addition, the pressure plate is manufactured and mounted in a way which W093~06783 2 1 2 1 0 3 6 i I ` PCT/USg2/08S71 assures uniform application of pressure across its entire surface. In accordance with another aspect of the present invention, the suc~ion rings are made by laser welding the stem to the ring and then forming the dovetail in the riny.
In accordance with another aspect ~f the invention, the applanat~rs have a diameter greater than the ring to overlap the ri.~g on two sidPs, thereby precluding any mo~ement of the applanator during use.
A more complete understanding of the present invention can be obtained by considering the following detailed description with the accompanying drawings in which:
FIG. 1 illustrates a keratome of the prior art.
FIG. 2 illustrates a cross-section of a portion of a human eye.
FIG. 3 illustrates a detail of the structure of a human cornea.
FIG~ 4 illustrates a suction ring and an end view of a keratoms in accordanc2 with the invention.
FIG. 5 illustrates a side view of a keratome in accordance with the invention.
FIG. 6 illustrates the movable plate used in the Xeratome of the~invention.
FIG. 7 illustrates a spring means for biasing the movable plate in accordance with the'invention.
FIG. 8 illustrates a blade in accordance with the , ; invention. ~
FIG. 9 illustrates a drive cam in accordance with the invention.
FIG. 10 illustrates the drive shaft for moving the 'W093/06783 2 1 2 1 0 3 6 P~T/US92/08~71 ,~
cutting blade. . ' FIG. 11 illustrates a detail of the alignment of the blade with the movable plate in accordance with the invention.
FIG. 12 illustrates an applanator in accordance with the invention.
FIG. 13 illustrates the markings on the upper inner sur~ace ~he applanator.
DETAILED DESCRIPTION
Referring to FIGS~ 4 and 5, the main frame of keratome 40 is made from a single block of stainless steel having do~etails 41 and 42 formed in the lower edges thereof.
Threaded connection 43 is at the rear of keratome 40 and ha~
bore 44 cut therein. A drive shaft fits into bore 44.
Connection 43 attaches keratome 40 to suitable dri~e apparatus, not shown and well known per se in the art, for example for dental drills and keratomes of the prior art.
Chambers 46 and 47 extend from side to side through keratome 40. Chamber 46 is partially defined by curved surface 48 which extends over substantially the whole length of the blade, except for an exposed portion in region 49.
The blade is located in slot 51 which extends from side to Z5 si~e and connects chambers 4~ and 47. Chamber ~7 receives the drive cam which moves the blade from side to side. Bore 4 c:onnects with chamber 4 7 .
Cha~ber 4 6 does not extend to the top of keratome 4 0, forming braces 52 on each side of the top which interconnect the front and rear pcrtions of keratome 40, grea~ly stiffening it to prevent any distortion of the original configuration, which would adversely affect the precision of the cut. Braces 52, as illustrated in FIG. 4, allows access to chamber 46 through the top of keratome 40.
A~terna~ively, braces 52 could be, a surface extending from side to side, enclosing the top of chamber 46.
The front por~ion of keratome 40 defines chamber 53 ~or receiving the movable plate and bias spring, as described in conjunction with FIGS. 6 and 7. Bore 55 passes through the upper surface of chamb~r 53 and receives column 62 (FIG. 6j.
Knob 56 contains a screw with extends through bore 55 to engage threaded bore 63.
In one embodiment of the inYention, the length of keratome 40, not including connector 43, was l.350 inches.
The radius of curvature of surface 48 was 0.~25 inches. The radius is not critical although it is preferably large with respect to the dimensions of chamber 46. What is important is that the blade be tangential or nearly tangential to surfaGe 48:at their intersection, point 58. This ~ relationship, curved~surface 48, and the volume of chamber :: . 46 as~ure that the corneal disk will not fold or ~ind and is easily removed fro= the keratoma by the surgeon.
Chamber 47 is preferably machined to dimensions eq~al to the dimensions of the cam, plus .0005 inch~ This precludes unwanted movement of the cam and assures steady driving of the blade. Similarly~ slot 51 is prefera~ly machined to the thickness of the blade, plus ~0005 inch.
This prevents the blade from fluttering as it vscillates, ~s W093/06783 ~ I O ~ 6 PCTlUS92/08571 seen in kerato~es of the prior art. Since keratome 40 is machined from a single block of steel, the height of slot 51 can ~e precisely controlled, in contrast to the two piece assem~ly of the prior art.
Slot 51 is angled with respect to the bottom of the keratome. In the prior art, this anyle was tw~nty~six degrees or more, In the present in~ention, it has been found that a blade angle of less than fifteen degrees is required. A preferred embodiment of thé present invention uses an angle of nine degrees relati~e to the bottom of the keratome. It is belie~ed that this causes the blade to slice rather than scrape the~cornea.
FI~. 6 is a top view of the adjustable p~ate in accordance with the invention. Plate 61 is attached to column 62 having threaded bore 63 therein. Plate 61 preferably has a trapezoidal shape to permit assembly in only one direction. Chamber 53 also has a orresponding trapezoidal cross-section in a plane parallel to the bottom ~ of keratome 40. ~ Edges 64 and 65 are parallel. Edges 66 ar.d 67 are not parallel~::but draw closer~to one another toward edge 6S. The~amount of taper is a matter of design. A
taper of 0.0 4 inch per ~inch has been found suitable. Edge 65 is located adjacent the blade. ~olumn 62 is of :: sufficient diameter~, e.g. 0.18 inches, to assure tha~ plate ~ 61 can be calibrated :to~the desired position and not change duxing use. Bore~63 preferably has a fine thread to allow small adjustments to be made:in the space between tbe plate : ~ and the blade,~because that space primarily determines the thickness of the cut. Sixty threads per inch has been found 1~
W~93/06783 ~ P~T/US92/0~571.
suitable. 21 2 i 0 3 6 The adj~stable plate is preferably made from a single piece of stainless steel. This assures stability between the bolt and the plate itself. The bottom surface of plate 61 is ground ~lat to within .0005 inches and then lapped.
The flatn~ss assures an accurate.cut and the l~pping assures that the cornea will not be scratched or otherwise damaged by the tool. In addition, the lower portion of edge 65 is beveled and has a radius, as further described in connection with FIG. ll.
YIG. 7 illustrates spring means used to bias the adjustable plate. Specifically, ~pring means 70 comprises resi~ient, annular disks 71 and 72 having oppositely curved portions 73 and 74. In addition, a part of the pe~imeter of each disk is flattened to assure that the disks cannot r~tate relative to one another during us~. Flats 75, 76, 77 and 78 are para1lel to the inner side walls of chamber 53 and are slightly spaced therefrom. ~he upper surface of disk 71 rests on the inside of the upper surface of chamber 53. The lower surface of disk 72 res~s on the upper surface of adjustable pIate 61. Bolt 62 fits within the opening in the center of dis~s 71 and 72. ~hile onIy two disks are shown, more disks can be used. In addition J d~pending upon the height of chamber 53, flat annular disks can be added ` 25 between the curved resilient disks. It is preferred that the range of movement of plate 61 be limited so that the maximum depth of cut does not exceed the thickness of the : average cornea, five hundred and twenty microns.
FIG. 8 illustrates a blade in ccordance with the W093/06783 212 I 0 3 6 PCT/US92/0~$71 inventionr The blade cGmprises surgical steel cut to the ~
width of k~ratome 40. ~dge 82 is sharpened as described in conjunction with FIG. 11. Opposite edge 82 is keyway 83 for receiving a key from the drive cam illustrated in ~IG. 9.
Blade 81 typically has a thickness of 0.00~ in.
Cam g0 is a rectangular block ha~ing the same width as the keratome. Recess 91 is ~ormed in a broad face, forming shoulders 92 and 93. Slot 94 i5 formed in recess 91. Key 95 is formed on the bottom surface of cam 90 and has a shape corresponding to keyway 83, into which it fits. It is preferred that the recess and slot not extend into the bottom surface adjacent key 9S to assure a full bearing surface for the cam.
. In use, key 95 is inserted into keyway 83 in blade 81 1~ and the two together slid sideways into the keratome block illustrated in FIG. S. The slotted major face of cam 90 must face connector 43 to accept the drive shaft.
FIG. ~0 il~ustrates a portion of the drive mechanism, specifically the drive shaft and pin. The mechanis~ for : 20 turning the driveshaft is well ~own per se in the art.
DriYe shaft 96 ends in a flat face having pin 98 eccentrically mounted thereon. .The distance between the axis 97 of shaft 96 and axis ~9 of p.~n 98 is the stroke of : the blade. The stroke is a matter of design, but is typically 0.150 in. The :end of shaft 96 fits within recess : 91 of cam 90~ Pin 98:fits into slot 94. As drive shaft 96 rotates, the rotational motion is converted into reciprocal motion by cam 90l which drives blade Bl from side to side in keratome 40. It is pr ferred that the shaft be spring W~93/06783 2121 0 3 6 P~T~US9X/08~71 i loadsd to provide some compliance along its length while it is driving cam 90.
Because of the recess forming shoulders 92 and 93, and the f~ct that the recess does not extend through to the key, one obtains a safety advantage if the pin should break off from drive shaft g6 in that the cam and blade would be trapped within their cham~rs by the drive shaft which fits in recess 91.
FIG. 11 illustrates the relationship between the cutting edge of the blade and the corner of adjustable plate 61. The blade is preferably symmetrical about axis ~10.
The edge of blade 81 is formed by grinding at an angle of six degrees relative to axis 110 in region 111. This is followed by honing at an angle of eight degrees in region 112, which is followed by honing at an angle of eleven degrees in tip 114. This edge treatment has been found to produce a superior cutting edge for cutting a cornea.
FIG. 11 also illustr~tes the edge treatment of the underside of edge 65, which is position~d adjacen~ blade ~1.
Edge 65 preferably has a bevel 121 of twenty-seven degrees, plus or minus one degree, relztive to lower surface 120.
The bevel need not~extend the full thickness of plate 61.
In a preferred embodiment of the present invention, it occupies only the lower half of edge 65. The extent of the bevel is a matter of design. Its purpQse is to provide cleara~ce and guidance for the corneal disk coming off the blade. The bevel and~the lower surface of adjustable plate 61 should not meet at a corner or edge. Thus, the surfaces are connected by ~adius 123. The specific value of the W093/067~3 2 1 2 1 ~ 3 6 P~T/US92/08~7l-radius is a matter of design, but the radius must be there t to protec~ the outer surface of the cornea. Lower surface 120 is tangent to the radius at their intersection, a line perpendicular to the plane of the drawing, represented by point 124.
In Dr. Barra~uer's work, the k~ratome did not h~ve a adjustable plate, but a set of interchangeable, fixed plates of different thicknesses. While the plate overlapped the blade, the location of the edge of the plate relatlve to the edge of the blade was not precise. In keratomes o~ the prior art having adjustable plates, such as illustrated in FIG. 1, the blade and the plate do not ovelap: the plate can be removed with the blade in place. In short, it has not been recognized that the location o~ the edge o~ the blade relative to the edge of the plate is important, It has been found that th effectiveness of the cut depends, in part, upon the locations of the edge of blade 81 and the corner of plate 61. Specifically, optimum results are obtained if point 124 i5 located above tip 114 of blade 81; i~e. between lines 126 and 127. It is belie~ed khat locating point 124 :above tip 114 provides support for the cornea during and immediately a~ter cutting the cornea, thereby improving the smoothness of the cut, particularly at .
the end of the cut~ which has heretofore been a problem ~` 25 area. Because some overlap is good does not mean that mor~
overlap is better. It:bas also been found that greater overlap produces in~erior cuts, compared to that obtained with the pl~te prop~rly located horizontally.
Referring to FI~. 4, suction ring 140 is placed over WO 93/(~67/~3 2 1 2 1 0 3 6 1 P~r/US~2/~57l , ~..
corne~ 141~ Cir~ular opening 142 i5 located ~ver the center of the front of the eye. Suction is provided thxoug~ handle 145, which is hollow and has fitting 146 at the end thereo~
for connection to a vacuum system. ~ore 147 connects handle 145 with the interior of ring 140. The reduced pressure draws cornea 1~1 up into aperture 142, which typically has a diameter of 11.25 mm. Dovetails 41 and 42 of keratome 40 fit into corresponding dovetai's 151 and 152 in suction ri~g 140. The front of the keratome is inserted into the channel and the keratome (with the blade oscillating) slides across ring 140, cutting a disk from the cornea. The thickness of the disk is regulated by the setting of adjustablé plate 61 before the operation.
Xn the prior art, the rin~ was machined and the handle attached, either by welding or by screwing the threaded end of the h~ndle into a threaded bore in the ring. The screw fitting was not a reliable connectlon, weak and prone to leakage. Welding the handle distorted the geometry of the ring so that the dovetail joints did not function smoothly.
In accord~nce with another aspect of the invention, the ring is machined, except for the dovetails. The handle is : attached by laser welding, which heats the body of the ring very little, and then the dovetails are formed. ~he result is a precise, smooth joint between the keratome and the ring.
The diameter and thickness of the disk removed from the cornea depends upon the thickness of the suction ring and the depth of cut as determined by the setting ~f adjustable plate 61. Choosing the right suction ring is done with what W093/06783 PCT/VSg2/08~71 . is known as an applanator; a transparent, acryllc cyllnaer havincS a domed or spherical top to give some enlarge~ent of the viewing area. FIG. 12 illustrates an improved ~ applanator in accordance with another aspect of the ', 5 invention. Applanator 155 is of greater diameter than ring ~ 157 and has shoulder 158 formed therein for engaging the outside o~ ring 157 at each en~ of the channel. The sidewall extends down between the dovetails in ring 157, not shown in FIG~ 12. Thus, applanator 155 cannot move relative `l 10 to ring 157, thereby giving a consistent view of the cornea.
'! Flats are formed in the sides of the applanator, as in the "
prior art, with grooves for clearing the handle. In ., accordance with the invention, the grooves are dimensioned to fit closely around the handle, thereby further stakilizing the measurement and assuring that the applanator :j and ring are located accurately.
FIG. 13 illustrates the indicia marked on interisr surface 159 of applanator 155. The inner circle has a ; diameter equal to that marked on the applanator (3.5-6.5 ~l 20 mm.) and aids in centéring the applanator. The outer circle .'. has a diameter of 7.25 mm., which is the standard diameter of the first disk~ cut. The crosshairs aid in centering the ring and, in par~icular, aid in re-centering the ring for the second cut. Induced astigm~tism can occur from several causes, one of which is that the ring was not centered for the second cut. (The second cut removes a smaller diameter disk 50 the first ring must be removed and a thinner ring ~;, used for the second cut.) The kera~ome is preferably machined from a single block ~ .
WOg3/06783 21210 3 ~ PCT/US92/08~71 'o 400 series stainless steel ~y what is known per se ln Ine~
~ art as EDM (electron discharge machininy). In order to ! assure the stability of the steel, it i5 heat treated (annealed~ pri~r to cutting. The various channels, bores, S and s'ots can then be cut in a reproducible manner, in part 3 due t:o ~he stability of the material and in part due to the precision of EDM.
There is thus provided by the invention an i~,proved keratome capable of making precise cuts wherein each cut has 3 lO smooth edges and is free of ridges or valleys. Because of ; the smoothness of the cut, corrections of low and mid-myopia `'t are achievable, Having thus described the invention, it will be apparent to those of skill in the art that many , 15 modifications can ~e made withln the invention. For '~ example, while descri~ed in conjunction with a particular procedure, the use of the invention is not so limited. The ;i invention can be used wherever smooth cuts of delicate tissue are desired. Although a dovetail connection between the keratome and the suction ring has been shown and described, it~is understood that other connections providing the same function~can be used,~e.g. a bead and cove. While - described as a threaded column on the adjustable plate receiving a threaded connector from the top of the keratome, it is understood that the reverse is equally effecti~e: a threaded bolt attaohed to the plate fitting within a threaded column from the top of the keratome.
~ What is claimed is:
,i~
.~
:,
Claims (10)
1. In a keratome for performing keratomileusis in-situ, said keratome having an elongated body, an adjustable plate at a first end of said body and having a major surface facing outwardly from said body, said adjustable plate movable within said body in a direction perpendicular to said major surface for controlling the thickness of a cut made with said keratome, and an oscillating blade within a second end of said body opposite said first end, said blade having a cutting edge extending past said major surface, the improvement comprising:
said blade being positioned at an angle less than fifteen degrees relative to said major surface.
said blade being positioned at an angle less than fifteen degrees relative to said major surface.
2. The keratome as set forth in claim 1 wherein said blade is positioned at an angle of nine degrees relative to said major surface.
3. The keratome as set forth in claim 1 wherein said adjustable plate terminates in an edge adjacent said blade and the cutting edge of said blade slightly overlaps the edge of said adjustable plate.
4. The keratome as set forth in claim 3 wherein said edge of said adjustable plate is beveled to form a beveled portion.
5. The keratome as set forth in claim 4 wherein said beveled portion is at an angle of twenty-seven degrees relative to said major surface.
6. The keratome as set forth in claim 4 wherein the beveled portion and said major surface are joined by a curved portion.
7. The keratome as set forth in claim 6 wherein the said major surface intersects said curved portion along a tangent.
8. The keratome as set forth in claim 7 wherein said major surface and said curved portion intersect along a line located above said cutting edge.
9. In a keratome having a cutting blade extending from a slot and an opening above the blade for receiving the tissue to be cut, the improvement comprising:
a portion of said opening being defined by a curved surface and wherein said slot intersects said surface and is approximately tangential to said surface.
a portion of said opening being defined by a curved surface and wherein said slot intersects said surface and is approximately tangential to said surface.
10. In a keratome having a front portion containing an adjustable plate and a back portion containing an oscillating blade for cutting tissue, said front portion and said back portion being connected by a bottom portion, the improvement comprising:
a pair of arms interconnecting said front portion and said back portion, for stiffening said keratome.
a pair of arms interconnecting said front portion and said back portion, for stiffening said keratome.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77517891A | 1991-10-11 | 1991-10-11 | |
| US775,178 | 1991-10-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2121036A1 true CA2121036A1 (en) | 1993-04-15 |
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ID=25103572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002121036A Abandoned CA2121036A1 (en) | 1991-10-11 | 1992-10-08 | Improved sectioning device for lamellar surgery |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5342378A (en) |
| EP (1) | EP0607279A4 (en) |
| AU (1) | AU668889B2 (en) |
| CA (1) | CA2121036A1 (en) |
| WO (1) | WO1993006783A1 (en) |
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| US5591174A (en) * | 1994-02-02 | 1997-01-07 | Chiron Vision Corporation | Microkeratome and method and apparatus for calibrating a microkeratome |
| US5752967A (en) * | 1995-07-27 | 1998-05-19 | Kritzinger; Michiel S. | Corneal surface marker and marking method for improving laser centration |
| US5934285A (en) * | 1995-07-27 | 1999-08-10 | Michiel S. Kritzinger | Method for reducing irregular astigmatism and debris/epithelium in the interface during lamellar corneal flap/cap surgery |
| US5755700A (en) * | 1995-07-27 | 1998-05-26 | Michiel S. Kritzinger | Corneal irrigation cannula and method of using |
| US5697945A (en) * | 1995-07-27 | 1997-12-16 | Black Hills Regional Eye Institute | Corneal surface marker and marking method for reducing irregular astigmatism during lamellar (LASIK) corneal surgery |
| US5800406A (en) * | 1995-11-22 | 1998-09-01 | Kritzinger; Michael S. | Corneal irrigation cannula |
| US5817115A (en) * | 1995-12-04 | 1998-10-06 | Chiron Vision Corporation | Apparatus for resecting corneal tissue |
| US6007553A (en) | 1996-02-07 | 1999-12-28 | Hellenkamp; Johann F. | Automatic surgical device control assembly for cutting a cornea |
| FR2751206B1 (en) * | 1996-07-22 | 1998-12-31 | Moria Sa | MONOBLOCK MICROKERATOME |
| JP3419789B2 (en) * | 1996-12-23 | 2003-06-23 | インスティテュト バーラケール デ アメリカ | Microkeratome |
| FR2758080B1 (en) * | 1997-01-06 | 1999-05-28 | Joseph Alain Hagege | INSTRUMENT FOR ELIMINATING THE RISK OF BLOCKING THE DEVICE USED IN EYE SURGERY FOR CUTTING THE CORNEA |
| US6030398A (en) * | 1997-05-30 | 2000-02-29 | Summit Technology, Inc. | Surgical microtomes |
| DE69718633T2 (en) * | 1997-08-06 | 2003-09-11 | Sis Ltd Surgical Instr Systems | Microkeratome for corneal surgery using laser |
| FR2767677B1 (en) * | 1997-09-04 | 1999-11-05 | Moria Sa | MICROKERATOME FOR OPTALMOLOGICAL SURGERY |
| US6610075B1 (en) * | 1997-10-24 | 2003-08-26 | Becton, Dickenson And Company | Keratome with suspended stabilized blade, improved suction ring with applanator and guided engagement with keratome cutter head, automated translation of the cutter head, and blade insertion tool |
| CN1285723A (en) | 1997-11-21 | 2001-02-28 | 霍肯工业公司 | Optialmic surgical system and method |
| US6626924B1 (en) | 1998-06-01 | 2003-09-30 | Peter J. Klopotek | Surgical microtomes |
| US6599305B1 (en) | 1998-08-12 | 2003-07-29 | Vladimir Feingold | Intracorneal lens placement method and apparatus |
| US6083236A (en) | 1998-08-12 | 2000-07-04 | Feingold; Vladimir | Keratome method and apparatus |
| US5989272A (en) * | 1998-10-05 | 1999-11-23 | Barron Precision Instruments L.L.C. | Keratome for performing eye surgery and method for using same |
| US6254619B1 (en) * | 1999-12-28 | 2001-07-03 | Antoine Garabet | Microkeratome |
| US6540760B2 (en) | 2000-06-23 | 2003-04-01 | Oasis Medical, Inc. | Cutting blade and cutting blade assembly |
| DK1891916T3 (en) * | 2000-09-01 | 2011-08-29 | Alexander Dybbs | Eye surgical system |
| US6436113B1 (en) * | 2000-09-18 | 2002-08-20 | Thomas A. Burba | Eye positioner |
| US6923821B2 (en) * | 2001-02-28 | 2005-08-02 | Theodore Wortrich | Microkeratome blades and methods of making |
| US6805698B2 (en) * | 2002-04-03 | 2004-10-19 | Alcon, Inc. | Microkeratome blade |
| US20040127922A1 (en) * | 2002-12-30 | 2004-07-01 | Cull Laurence J. | Microkeratome cutting blade assembly |
| JP2006521868A (en) | 2003-04-07 | 2006-09-28 | ボシュ・アンド・ロム・インコーポレイテッド | Bar link drive system for microkeratome |
| DE10317972B3 (en) * | 2003-04-17 | 2004-09-30 | Gebauer Gmbh | Knife used in a microkerotome comprises a blade having a specified cutting angle, free angle and blade radius |
| DE502004002627D1 (en) * | 2003-05-02 | 2007-02-22 | Albert Daxer | DEVICE FOR CUTTING THE HORN SKIN OF AN EYE |
| MX2008011680A (en) | 2006-03-16 | 2008-12-10 | Daxer Albert | Structural member. |
| CN101460114B (en) | 2006-05-23 | 2011-07-06 | 阿尔贝特·达克瑟尔 | Corneal implant for correction of impaired vision in the human eye |
| US8551075B2 (en) | 2006-06-02 | 2013-10-08 | Kci Medical Resources | Assemblies, systems, and methods for vacuum assisted internal drainage during wound healing |
| US7922736B2 (en) | 2007-03-29 | 2011-04-12 | Technolas Perfect Vision Gmbh | Stepped microkeratome blade holder |
| WO2018029509A1 (en) * | 2016-08-09 | 2018-02-15 | Gebauer-Kloptek Patent Verwaltung Ug | Surgical apparatus and blade elements for slicing lamellar segments from biological tissue |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2691377A (en) * | 1952-09-22 | 1954-10-12 | George J Hood | Power-driven dermatome |
| GB1144984A (en) * | 1967-06-27 | 1969-03-12 | Austenal Europa Inc Zweigniede | Improved dermatome |
| US4180075A (en) * | 1977-04-05 | 1979-12-25 | Marinoff Gerald P | Ophthalmological surgical instrument |
| FR2489141A1 (en) * | 1980-09-03 | 1982-03-05 | Sevifra | SURGICAL APPARATUS FOR PRECISE CUTTING OF THE CORNEA |
| US4423728A (en) * | 1982-02-26 | 1984-01-03 | Lieberman David M | Cam-guided trephine |
| DE3409798C1 (en) * | 1984-03-16 | 1985-10-24 | Jörg Dr.med. 4630 Bochum Krumeich | Fixing arrangement for holding a corneal disk removed from the human eye |
| DE3433581C2 (en) * | 1984-09-13 | 1986-08-07 | Fa. Carl Zeiss, 7920 Heidenheim | Device for laminating, refractive corneal surgery |
| US4750491A (en) * | 1984-11-08 | 1988-06-14 | Allergan, Inc. | Trephine and method |
| US4763651A (en) * | 1984-11-08 | 1988-08-16 | Allergan, Inc. | Trephine and method |
| US4807623A (en) * | 1986-05-30 | 1989-02-28 | David M. Lieberman | Device for simultaneously forming two incisions along a path on an eye |
| US4796623A (en) * | 1987-07-20 | 1989-01-10 | The Cooper Companies, Inc. | Corneal vacuum trephine system |
| US5133726A (en) * | 1990-02-14 | 1992-07-28 | Ruiz Luis A | Automatic corneal shaper |
-
1992
- 1992-10-08 AU AU27632/92A patent/AU668889B2/en not_active Ceased
- 1992-10-08 CA CA002121036A patent/CA2121036A1/en not_active Abandoned
- 1992-10-08 EP EP92921585A patent/EP0607279A4/en not_active Withdrawn
- 1992-10-08 WO PCT/US1992/008571 patent/WO1993006783A1/en not_active Application Discontinuation
-
1993
- 1993-08-20 US US08/110,323 patent/US5342378A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU2763292A (en) | 1993-05-03 |
| EP0607279A1 (en) | 1994-07-27 |
| WO1993006783A1 (en) | 1993-04-15 |
| US5342378A (en) | 1994-08-30 |
| AU668889B2 (en) | 1996-05-23 |
| EP0607279A4 (en) | 1995-08-09 |
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| Date | Code | Title | Description |
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