Disposable ophthalmic instrument for performing radial keratotomy on the cornea

The present invention is an ophthalmic instrument for use in performing radial keratotomy on the cornea of a patient for correcting myopia and/or astigmatism of the patient. The ophthalmic instrument includes a surgical blade having a suitable width for making an incision into the cornea of the patient and an elongated handle which is formed out of a plastic material and to which the surgical blade is fixedly coupled. The ophthalmic instrument also includes a depth-guide which is a hollow, cylindrical member and which is formed out of a plastic material. The depth guide has a first and second end and also has a pair of protruding arms, each of which has a first end and a rounded second end and which extend parallel to each other and to the longitudinal axis of the hollow, cylindrical member from the first ends of the protruding arms for most of their length and then sharply converge adjacent, but not contiguous to the rounded second ends of the protruding arms the second ends of the protruding arms being spaced apart a distance slightly greater than the width of the surgical blade whereby the second rounded ends of the protruding arm slidably rests on the surface of the cornea in order to control the incision depth of the surgical blade, slidably coupled to the elongated handle. The depth-guide has it position on the elongated handle pre-set to a depth in the range of 0.20 millimeters to 1.2 millimeters.

FIELD OF THE INVENTION 
The present invention relates to an ophthalmic instrument for performing 
the procedure of radial keratotomy on a cornea and more particularly to a 
disposable ophthalmic surgical knife having a guide foot which has been 
pre-set at a particuliar depth and which does not block the view of the 
ophthalmologist while he is making the incisions in the cornea. 
BACKGROUND OF THE INVENTION 
U.S. Pat. No. 3,776,230, entitled Method of Rapidly Reshaping the Cornea to 
Eliminate Refractice Errors, issued to Charles W. Neefe on Dec. 3, 1973, 
teaches a method of correcting the refractive errors of the eye by 
changing the shape of the cornea by softening the cornea tissue by the 
application of heat and reshaping the convex cornea to the curvature of 
the surface of a concave mold which is applied to the cornea. 
U.S. Pat. No. 4,298,004, entitled Surgical Method for altering the 
Curvature of the Cornea of Rabbits, issued to Ronald A. Schachar and 
Norman S. Levy on Nov. 3, 1981, teaches a method for altering the radius 
of curvature of the cornea together with an appratus for use therein. The 
apparatus includes a circular ring which can be placed over the eye for 
concentrically surrounding the cornea and blade which is mounted for 
retractable movement to and away from the cornea. The blade is also able 
to rotate through a limited arc so that a sector shaped incision can be 
made in the cornea. Collagen is injected into the sector-shaped incision 
to alter the radius of curvature of the cornea. 
U.S. Pat. No. 4,180,075, entitled Ophthalmological Surgical Instrument, 
issued to Gerald P. Marinoff on Dec. 25, 1979, teaches a hand held 
surgical instrument for performing ophthalmological incision in the form 
of an arc for cataract surgery. 
Ophthalmologists have long been concerned with correcting the hyperopia in 
the eye and defects which relate to the curvature of the cornea. A 
well-known method for correcting hyperopia includes corrective lenses, 
such as eye glasses or contact lenses. These methods have obvious 
drawbacks as they do not form an integral part of the eye structure. Eye 
glasses and contact lenses are often bothersome to wear and are subject to 
loss or breakage. Contact lenses present additional problems such as eye 
infections and corneal damage related to excessive abrasion and 
scratching. 
A need therefore existed for a method and apparatus for correcting 
hyperopia without external corrective lenses. Further, a need also existed 
for the correction of hyperopia wherein the radius of curvature of the 
cornea is permanently altered. 
Svyatoslav N. Fyodorov, M.D., and Valery V. Durnev, in an article entitled 
"Operation of Dosaged Dissection of Corneal Circular Ligament in Cases of 
Myopia of Mild Degree", published in the Annals of Ophthalmology, 
December, 1979, pages 1885-1890, reported their results of using radial 
keratotomy on 60 eyes of 30 patients who had bilateral, non-progressive 
myopia ranging from 0.75 to 3.0 diopters. The central optical zone was 
delimited by a light touch of a marker. The cornea was then marked by 
lines forming 16 even segments by a special device with the markings 
resembling the spokes of a wheel and the delimited optical zone resembling 
the hub of the wheel. A razor blade in a blade holder was used to make 16 
radial partial thickness incisions of the cornea along the lines forming 
the 16 even segments from the border of the delimited central optical zone 
to the limbus. The depth of the incision approaches three-fourths of the 
thickness of the cornea. Following the procedures, the eye was irrigated 
with a weak physiological saline solution. A solution of antibiotic was 
then injected under the conjunctiva and the eye patched. 
In the article, Fyodorov and Durnev stated that a guarded blade had been 
used by Sato who published in 1953 an article entitled "A New Surgical 
Approach to Myopia", in the American Journal of Ophthalmology, Volume 36, 
page 823. 
U.S. Pat. No. 3,945,117, entitled Surgical Blade with Adjustable Blade 
Guard, issued to John R. Beaver on May 23, 1976, teaches a surgical knife 
assembly in which a blade is provided with a guard for limiting the depth 
guard for limiting the depth of cut. The guard is formed of a resilient 
material as plastic, and frictionally grips the blade, so that the guard 
is adjustable on the blade by the application of a predetermined amount of 
axial force, with the force required for adjustment being considerably 
greater than the force that is applied thereto during a cutting procedure. 
An adjustment tool is also provided, the tool and the blade having 
cooperating engaging portions to permit accurate adjustment of the 
position of the guard on the blade between incisions during a surgical 
procedure. 
U.S. Pat. No. 4,006,746, entitled Surgical Knife, issued to John Edwards on 
Feb. 8, 1977, teaches a manual surgical knife which includes an elongated 
knife blade and an elongated blade guide. 
U.S. Pat. No. 4,026,295, entitled Surgical Knife, issued to David M. 
Lieberman on May 31, 1977, teaches a surgical knife for achieving a 
precise incision for cataract extraction. 
U.S. Pat. No. 3,789,830, entitled Disposable Lancet, issued to Sven-Erik 
Malmstrom on Feb. 5, 1974, teaches multiple disposable lancets which are 
punched from a strip of sheet steel in order to obtain economy in the 
manufacturing operation. 
SUMMARY OF THE INVENTION 
In view of the foregoing factors and conditions which are characteristic of 
the prior art, an ophthalmic instrument is set forth for performing the 
procedure of radial keratotomy on the cornea of a patient which is a 
surgical knife having a guide foot which has been pre-set at a particular 
depth. The ophthalmic instrument is disposable and is adapted so as to not 
block the view of the ophthalmologist while he is making incisions in the 
cornea of a patient. 
In accordance with the present invention, the embodiment of an ophthalmic 
instrument for use in performing radial keratotomy on the cornea of a 
patient for correcting myopia and/or astigmatism of the patient is 
described. The ophthalmic instrument includes a surgical blade having a 
suitable width for making an incision into the cornea of the patient and 
an elongated handle which is formed out of a plastic material and to which 
the surgical blade is fixedly coupled. The ophthalmic instrument also 
includes a depth-guide which is a hollow, cylindrical member and which is 
formed out of a plastic material. The depth guide has a first and second 
end and also has a pair of a protruding arms, each of which has a first 
end and a rounded second end and which extend parallel to each other and 
to the longitudinal axis of the hollow, cylindrical member from the first 
ends of the protruding arms for most of their length and then sharply 
converge adjacent, but not contiguous to the rounded second ends of the 
protruding arms, the second ends of the protruding arms being spaced apart 
a distance slightly greater than the width of the surgical blade whereby 
the second rounded ends of the protruding arm slidably rest on the surface 
of the cornea in order to control the incision depth of the surgical 
blade, slidably coupled to the elongated handle. The depth-guide has its 
position on the elongated handle pre-set to a depth in the range of 0.20 
millimeters to 1.2 millimeters.

DETAILED DESCRIPTION 
In order to best understand the present invention, it is first necessary to 
refer to the following description of the prior art in conjunction with 
FIG. 1 of the drawing. Referring to FIG. 1, an ophthalmic instrument 10 
includes an elongated handle 11 and a surgical blade 12 which is fixedly 
coupled to the elongated handle 11. The ophthalmic instrument 10 also 
includes depth-guide 13 which has a protruding arm which extends 
parallelly over the non-cutting edge of the surgical blade 12 and which 
has a pair of prongs extending further, but bending down so that the 
surgical blade 12 is disposed between them whereby the pair of prongs 
limit the incision depth of the ophthalmic instruction 10. 
Referring to FIG. 2, an ophthalmic instrument 20 according to the present 
invention for use in performing radial keratotomy on the cornea of a 
patient for correcting myopia and/or astigmatism of the patient is set 
forth, the instrument 20 includes an elongated handle 11 and a surgical 
blade 12 being fixedly coupled to the elongated handle 11 and having a 
suitable width for making an incision into the cornea of the patient. The 
elongated handle 11 may be formed out of either a plastic material or a 
metallic material. 
Referring to FIG. 2, in conjunction with FIGS. 3-7, the ophthalmic 
instrument 20 also includes a depth-guide 21 which is a hollow, 
cylindrical member 22 and which is formed out of either a plastic material 
or a metallic material. The depth guide 21 has a first and second end and 
also has a pair of a protruding arms 23, each of which has a first end and 
a rounded second end 24 and which extend parallel to each other and to the 
longitudinal axis of the hollow, cylindrical member 22 from the first ends 
of the protruding arms 23 for most of their length and then sharply 
converge adjacent, but not contiguous to the rounded second ends 24 of the 
protruding arms 23. The rounded second ends 24 of the protruding arms 23 
are spaced apart a distance slightly greater than the width of the 
surgical blade 12 whereby the round second ends 24 of the protruding arm 
23 slidably rest on the surface of the cornea in order to control the 
incision depth of the surgical blade 12. The depth-guide 21 is slidably 
coupled to the elongated handle 11. The depth-guide 21 has its position on 
the elongated handle 11 pre-set to a depth in the range of 0.20 
millimeters to 1.2 millimeters. A set screw 25 or a solder tack secures 
the depth-guide in place. 
In their article, Steven G. Kramer, Edward Q. Yavitz and Jukka Sulonen, 
entitled "Precision Standardization of Radial Keratotomy", published in 
Ophthalmic Surgery, August, 1981, Volume 12, Number 8, pages 561-566, 
discuss the need for a precision ophthalmic instrument for performing the 
procedure of radial keratotomy on the cornea of a patient. They recommend 
a suction template with a central opening for a visual axis. The key to 
the ophthalmic instrument 20 according to the present invention is that it 
is a surgical knife which has a guide foot 21 which can be pre-set at a 
particular depth. Furthermore, the ophthalmic instrument 20 is disposable 
and does not block the view of the ophthalmologist while he is making 
incisions in the cornea of a patient in either cutting direction as does 
the ophthalmic instrument 10 of the prior art. 
Referring to FIG. 8 and FIG. 9, the incisions in the cornea must be precise 
in order to obtain the proper result. Every step which can be eliminated 
in preparing the ophthalmic instrument 20 for performing a radial 
keratotomy aids the ophthalmologist in performing this procedures. By 
using a pre-set, sterile, disposable ophthalmic instrument, an 
ophthalmologist is able to concentrate on performing the procedure. 
From the foregoing, it can be seen that an ophthalmic instrument for 
performing radial keratotomy on the cornea of a patient has been 
described. It should be noted that the sketches are not drawn to scale and 
that distance of and between the figures are not to be considered 
significant. 
Accordingly, it is intended that the foregoing disclosure and showing made 
in the drawing shall be considered only as an illustration of the 
principles of the present invention.