A miniature surgical instrument that is particularly useful for removing ferrous foreign particles from an eye, includes a housing and a wire wound coil positioned within the housing. A magnetizable, axially elongated probe includes a first tip portion that is positioned externally of the housing and a second, body portion that is within the housing and which is surrounded by the coil. A switch is coupled to the coil and is adapted to interconnect the coil to a source of electrical energy so that when the switch means is operated the coil is energized and the probe is magnetized.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to surgical instruments and more 
particularly to a miniature surgical instrument that is adapted to remove 
ferrous foreign particles from an eye. 
2. Description of the Prior Art 
Generally speaking, intraocular foreign bodies may classified as either 
magnetic or non-magnetic. The present invention is directed only to the 
former type and only that form of prior art will be discussed. 
Magnets have been used for some time in the removal of ferrous foreign 
objects in the eye. However, prior art structures have not been entirely 
satisfactory. One technique which has been used for many years is to 
locate the foreign body and to manipulate it by means of a relatively 
large magnet or electromagnet that is applied outside the eye. When the 
ferrous particle is brought near the surface an incision is made in the 
sclera and the particle is removed either by forceps or by the magnet. 
Several problems are related to this technique. For example, it may be 
necessary to remove one or more extra-ocular muscles in order to reach the 
operating site. Furthermore, damage may be done to the retina by removing 
the body through the wall of the eye, or damage may be done to the 
vitreous in moving the foreign body within the eye by the external magnet. 
In addition, it is frequently difficult to determine exactly where to cut 
the sclera in order to position the extracting tool directly over the 
foreign body and in such instances it is not uncommon that a larger 
incision than is absolutely necessary must be made. 
The earliest magnets that were used for the purpose of removing a ferrous 
foreign object from the eye were permanent magnets. However, with such 
type instruments, it was necessary for the ferrous foreign body to be 
virtually in contact with the pole tip of the magnet in order to remove 
the object. In order to determine the efficiency of an electromagnet that 
is used for the purpose of removing ferrous foreign bodies, the field 
strength and the gradient of the field strength must be determined. It is 
well known that the magnetic field of an electromagnet can magnetize a 
foreign body that is made of ferrous material and which is located in the 
eye. The gradient of the field strength of the magnet serves to pull the 
ferrous object towards the pole tip during that portion of time when the 
ferrous particle approaches the magnet. 
Another form of eye repair damage by foreign objects requires the surgeon 
to work within the eye through a pair of needle insertions that are less 
than 1 mm. in diameter. In one of the insertions, a bundle of glass fibers 
conducts light into the eye. Through the other insertion a series of 
surgical instruments can be inserted to work within the eye. In many cases 
a jell-like vitreous humor is removed and is replaced with a saline 
solution. After such a procedure the interior of the eye is optically 
cleared and the surgeon is able to see inside. When the foreign body is 
visable, for example it may be resting against the retina, the surgeon can 
then insert the tip of the probe comprising the present invention through 
one of the needle holes in the eye and bring it close to the ferrous 
particle. By pressing the button on the present invention a switch is 
closed and a coil is electrically energized so as to magnetize the tip of 
the probe to thereby cause the ferrous foreign body to adhere to the 
probe. Subsequently the foreign particle can be removed. If further 
manipulation is required releasing of the button demagnetizes the tip of 
the probe and the foreign body can easily be transferred to forceps or 
another instrument. 
SUMMARY OF THE INVENTION 
Briefly, the present invention provides an elongated housing of miniature 
size. A magnetizable, axially elongated probe is partially positioned 
within the housing. The tip portion of the probe extends outwardly while 
the body portion of the probe is contained within the housing and is 
surrounded by an electrical coil that is coupled to a switch that is 
interconnected to a source of electrical energy such as a battery that may 
also be contained within the surgical instrument. Thus, when the push 
button of the switch is depressed, the coil is energized and the tip of 
the probe is magnetized so that it may be used in the manner described 
hereinabove. 
Accordingly, it is an object of the present invention to provide an 
improved miniature surgical instrument that is adapted for removing 
ferrous foreign particles from an eye. 
Another object of the present invention is to provide a miniature surgical 
instrument, as described above, having an axially elongated probe that may 
be magnetized and demagnetized by the depression of a push button which 
actuates a switch. 
Still another object of the present invention is to provide a miniature 
surgical instrument, as described above, wherein the tip portion of the 
probe is hemispherical. 
A further object of the present invention is to provide a miniature 
surgical instrument, as described above, werein the tip portion of the 
probe is approximately 1.0 mm in diameter. 
Yet another object of the present invention is to provide a miniature 
surgical instrument, as described above, having a self contained-source of 
electrical energy. 
These and other objects, features and advantages of the invention will, in 
part, be pointed out with particularity, and will, in part become obvious 
from the following more detailed description of the invention, taken in 
conjunction with the accompanying drawing which forms an integral part 
thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing, there is shown a miniature surgical 
instrument 10 comprising the present invention. The instrument 10 includes 
a hollow housing 12 having external threads 14 and 16 at the forward and 
rearward ends thereof, respectively. A conical sleeve 18 having internal 
threads 20 is removably secured to the threaded end 14 of the housing 10. 
Similarly, an end cap 22 having internal threads 24 is removably secured 
to the external threads 16 at the rearward end of the housing 12. 
The conical sleeve 18 is provided with three coaxial and concentric bores 
26, 28 and 30. In a manner to be described more fully hereinafter, a probe 
generally designated by the reference character 32 is contained within the 
bore 30. An electrical coil, generally designated by the reference 
character 34, is contained within the bore 28 and a plug, generally 
designated by the reference character 36, is contained within the bore 26. 
The plug 36 is provided with a transverse shoulder 38 which abuts an 
internal, transverse wall 40 formed within the housing 12 proximate the 
forward end thereof. The coaction of the shoulder 38 and the wall 40 limit 
forward movement of the plug 36. First and second bores 42 and 44, 
respectively, serve to receive the rearward end of the probe and a portion 
of the coil 34. A metallic strap 46 that is used for grounding purposes is 
secured to the plug 36 by means of a set screw 48. The coil 34 is 
electrically connected to the strap 46 by means of a conductive lead 50. 
The end of the strap 46 that is remote from the set screw 48 bears against 
an internal portion of the housing 12 which is made of a metallic 
material. The plug 36 is provided with a seat 52 at its rearward end for 
the purpose of receiving a switch member 54. In the embodiment 
illustrated, the switch member 54 includes three terminals 56, 58 and 60 
which extend through openings 62, 64 and 66, respectively, that are formed 
in the rearward end of the plug 36. The coil 34 is also electrically 
coupled to the terminal 56 of the battery 54 by means of a conductive lead 
68. Terminal 58 of the switch 54 is electrically coupled to a metallic 
plate 70 by means of a conductive lead 72. 
A battery 74 is contained within the housing 12 and is provided with 
terminals 76 and 78 at the forward and rearward ends thereof, 
respectively. The terminal 76 bears against the metallic plate 70. At its 
opposite end, the terminal 78 of the battery 74 bears against a cup-shaped 
retainer 80 which contains a compression spring 82. A recess 84 formed in 
the end cap 22 receives the opposite end of the compression spring 82. 
Thus, the battery 74 is continuously urged in a forward direction so that 
the terminal 76 always bears against the plate 70 and so that the terminal 
78 is always in intimate electrical contact with a portion of the housing 
12. 
The housing 12 further includes a tapped hole 86 that is arranged to 
receive a collar 88 through which a push button 90 is inserted. A 
retaining ring 92 limits the push button 90 to inward movement only so 
that the contact button 94 of the switch 54 may be depressed manually. 
Turning now to the probe 32, it will be seen that there is provided a tip 
portion 96 and a body portion 98 that is somewhat larger in diameter than 
the tip portion 96. Furthermore, the tip portion 96 terminates in a 
hemispherical end 100. One section of the body portion 98 fits relatively 
snugly within the bore 30 formed in the conical sleeve 18 while another 
section of the body portion 98 fits relatively loosely within a bore 102 
formed through the coil 34. The rearwardmost end of the body portion 98 is 
loosely contained within the bore 42 formed in the plug 36. 
The probe in the present invention is made of a soft, magnetic material. It 
has been found that a hydrogen-annealed, Hy-Mu 80 alloy provides excellent 
results. The probe 32 described hereinabove and shown in the drawings is 1 
mm in diameter by 20 mm long with a hemispherical outermost end. However, 
other shapes may also be utilized. For example, a spoon-shaped probe may 
be used as well as a probe with a hole therein that is similar to the eye 
of a needle. Hy-Mu 80 is an iron-nickel-molybdenum alloy having a very 
high initial magnetic permeability, high maximum permeability, low core 
loss and good magnetic shielding. A typical analysis for such an alloy 
found useful in the practice of this invention is given as follows: 
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Carbon 0.05% 
Manganese 0.05% 
Silicon 0.30% 
Nickel 80.0% 
Molybdenum 4.0% 
Iron balance 
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These alloys are well known to those skilled in the art and are usually 
annealed in an oxygen-free, dry hydrogen atmosphere with a Dew Point below 
-40.degree. F. for two to four hours at 2150.degree. F. Then they are 
furnace cooled to 1100.degree. F. and thereafter from 1100.degree. F. to 
700.degree. F. cooled at a rate between 350.degree. F. and 500.degree. F. 
per hour. 
These alloys found useful in our invention have the ability to return to 
less than 0.2% of the original magnetization after having been subjected 
to oerstad of direct current magnetizing force. This prevents 
magnetizeable objects in bodies such as eyes from adhering to the probe 
after the current flow is stopped as would be the case when conventional 
probes having high magnetic remanence are employed. 
It will be evident from the foregoing that by depressing the pushbutton 90 
the switch 54 will interconnect battery 74 and the coil 34 and thereby 
magnetize the tip 96 of the probe 32. Releasing the push button 90 will 
demagnetize the tip 96 in order to permit further manipulation of the 
instrument 10 so that the foreign body can easily be transferred to 
forceps or to another instrument. 
There has been disclosed heretofore the best embodiment of the invention 
presently contemplated. However, it is to be understood that various 
changes and modifications may be made thereto without departing from the 
spirit of the invention.