Device for dilating a pupil and/or maintaining a pupil in a dilated state

A device for dilating a pupil and/or maintaining a pupil in a dilated state. The device includes a generally arcuate body having first and second ends. The outer peripheral edge of the body has an engaging formation adapted to engage the inner peripheral edge of an iris to retain the pupil in an expanded state, and at least one positioning arm extending generally outwardly from one of the ends of the body so as to remain external to the eye.

FIELD OF THE INVENTION 
The present invention relates to a device for dilating a pupil and/or 
maintaining a pupil in a dilated state. 
The invention has been developed primarily for use in ophthalmic surgery 
and will be described hereinafter with reference to this application. 
However, it will be appreciated that the invention is not limited to this 
particular field of use and can be utilised in other medical procedures 
where an opening is required to be expanded and maintained in the expanded 
state. 
BACKGROUND OF THE INVENTION 
It is advantageous in many ophthalmic surgical procedures for the pupil to 
be dilated as much as possible. A pupil is dilated when the iris retracts 
towards the outer edges of the eye. This normally occurs when the eye is 
deprived of bright light, for example, at night. 
When performing ophthalmic operations, such as replacing the lens of a 
patient's eye with an artificial intraocular lens, a dilated iris and 
pupil gives the surgeon a larger area to manipulate surgical instruments 
in order to operate on the human lens. The more area available to the 
surgeon reduces the risk of damaging the iris or other components of the 
eye due to unintentional contact with the surgical instruments. 
A common method of dilating the pupil is the use of chemical eyedrops. The 
eyedrops are formulated to trigger the expansion of the iris, resulting in 
a dilated pupil. However, such eyedrops are not effective on all patients 
and more surgically complicated measures are often required. Also, such 
eyedrops can "wear off" during an operation resulting in the iris 
retracting and reducing the pupil size. 
One method to dilate and maintain a pupil in the dilated state involves 
making four minor incisions at roughly 90.degree. intervals around the 
periphery of the cornea and inserting a small hook-like apparatus through 
each incision. The hooks engage with the inner circumferential edge of the 
iris and when retracted, pull the iris outwards to define an enlarged 
substantially square shaped opening. Another method, known as a 
sphincterotomy, involves making an incision into the cornea through which 
a blade is passed that makes radial cuts into the iris itself, thus 
allowing the iris to dilate and expose more of the lens. Both the above 
methods add extra time to the actual operation being performed and the 
latter involves considerable risk or damage to the patients iris. 
Moreover, the damage done in segmenting the iris during a sphincterotomy 
is irreversible and results in a permanently disfigured iris. 
It is an object of the invention, to overcome or ameliorate at least some 
of the deficiencies of the prior art. 
SUMMARY OF THE INVENTION 
According to a first aspect of the invention there is provided a pupil 
dilating device for dilating a pupil and/or maintaining a pupil in a 
dilated state, said device including a generally arcuate body made of a 
resilient material and having first and second ends, an outer peripheral 
edge of the body having an engaging formation adapted to engage the inner 
peripheral edge of an iris to retain the pupil in an expanded state, and 
two integrally formed positioning arms each extending generally outwardly 
from one of said first and second ends of the body respectively, so that 
the distal portions of the positioning arms remain external to the eye. 
Preferably also, the body is adapted to deform to a generally elongated or 
folded configuration able to be passed through an exterior incision in the 
eye and resiliently return to a substantially annular configuration 
engaging the iris edge. 
In one embodiment, a bridge member extends between the positioning arms, 
such that the arms are prevented from crossing over each other in a 
scissor type action when the dilating device is deformed into its folded 
configuration. Preferably, the bridge member is pivotally mounted at its 
ends to the positioning arms and includes a central hinge such that the 
positioning arms may be drawn towards each other to deform the dilating 
device into the folded configuration. 
Desirably, the body also includes a guide tab extending outwardly from and 
generally parallel to a diameter of the body for aiding insertion of the 
device, for supporting the body in engagement with the iris edge and also 
for preventing the body from "falling" through the pupil opening. 
In a preferred embodiment, the positioning arm or arms each terminate in a 
gripping formation. The formation provides a convenient gripping point for 
the device and also, if so desired, allows the positioning arms to be 
sutured to the eye. The gripping formation or formations may include a 
hole through which a suture thread may be passed. 
In another preferred embodiment, each of the arm or arms includes a 
proximal portion adjacent the body that extends close to the plane of the 
surface of the iris and a distal portion that is off-set in a direction 
away from the plane of the iris and which extends to the gripping 
formation or formations so as to allow the distal portion or portions to 
remain external to, but closely adjacent the surface of the eye whilst the 
device is in use dilating the pupil. 
The resilience of the body preferably provides a radially outwardly 
directed force capable of urging into and maintaining the body in a 
substantially annular configuration whilst engaging the iris to expand 
and/or maintain the pupil in the dilated state. 
In a preferred form, the engaging formation is desirably formed so as to 
define a continuous recessed channel between the ends. 
In a further embodiment, the body comprises a pair of circumferentially 
aligned parallel axially spaced apart incomplete rings and a series of 
circumferentially spaced apart curved joining members extending from one 
ring to the other to define said engaging formation. 
In another embodiment, the body is provided with a plurality of radially 
outwardly angled pairs of reaps, each pair of flaps defining a portion of 
the recess therebetween. 
The body is preferably made from a material selected from the group 
including prolene, poly methyl methacrylate, nylon, silastic, silicone 
polyimide, polyamide or a combination thereof, or any other material 
having the requisite properties of resilience and suitability for use in 
surgical procedures. 
In a further embodiment, an insert of a second material is contained within 
the body to give the required resilience. 
In a further embodiment, the body is sized to provide an inner diameter in 
the substantially annular configuration of between approximately 5.5 mm 
and 7 mm, the body itself has a radial thickness of between about 0.75 and 
1.25 mm. In this embodiment, the recess has an axial depth of about 1.12 
mm and the guide tab extends from the outer edge of the body by about 1.25 
mm. The distal portions of the arms are preferably offset from the 
proximal portions by about 1.5 to 2.0 mm in the axial direction. 
In yet another embodiment, regions of weakness may be included in the body 
to further facilitate resilient deformation between the expanded annular 
and the elongated or folded configurations. 
Desirably, the device is tinted for increased visibility to the surgeon. 
In the annular configuration, the arcuate body preferably has an included 
angle of between approximately 270.degree. and 340.degree..

PREFERRED EMBODIMENTS OF THE INVENTION 
Referring to FIG. 1 there is shown a human eye having a cornea 10, sclera 
11, anterior chamber 12, lens 14, iris 16, limbus 17, retina 18 and optic 
nerve 20. The iris 16 has an inner peripheral edge 22, the boundary of 
which defines the opening of the known as the pupil 24 (the black circle 
in the centre of an eye). 
As described previously, it is advantageous during surgery of the eye, for 
the pupil opening 24 to be as large as possible to permit access to the 
lens and other parts of the eye via incisions in the cornea or sclera. 
Referring to FIG. 2, there is shown in use a device 26 according to the 
invention for dilating the pupil and/or maintaining the pupil in the 
dilated state. The device 26 comprises a generally arcuate body 28 having 
first and second ends 35. The outer peripheral edge of the body has a 
recess 30 adapted to engage the inner peripheral edge 22 of the iris to 
retain the pupil in a dilated state. The device also includes positioning 
arms 34 which extend generally outwardly from the ends 35 of the body and 
remain external to the eye when the device is in use. The arms are more 
clearly shown in FIGS. 3 and 4. The recess 30 forms a continuous channel 
32 between the ends 35. Device 26 also includes guide tab 36 which extends 
from the body 28. 
Referring to FIGS. 3 and 4, the arms 34 can each be seen to include a 
proximal portion 38 adjacent to the body and a distal portion 40 
substantially parallel to, but offset from the proximal portion 38. The 
arms 34 terminate in gripping formations 44. 
If desired, the formations 44 also allow the surgeon to suture the arms 34 
to the sclera 11. Holes can be provided through the formations through 
which the suture thread may be passed. 
Referring in particular to FIG. 5, it can be seen that the body 28 is 
adapted to resiliently deform to a generally elongated or folded 
configuration as shown which is able to be passed through an exterior 
incision into the eye and, upon release, return to a substantially annular 
configuration, as shown in FIG. 4. Referring next to FIGS. 6 to 10, there 
are shown several alternative embodiments of the device according to the 
invention. 
The embodiment of the device shown in FIGS. 6 and 7 comprises a pair of 
circumferentially aligned parallel axially spaced-apart incomplete rings 
46 with a series of circumferentially spaced-apart joining members 48 
extending from one ring to the other to define the recess 30. 
The embodiment of the invention shown in FIGS. 8 and 9 is similar to the 
previously illustrated embodiments except that the body 28 is provided 
with a series of radially extending flaps 50 around its periphery. 
Furthermore, this embodiment includes regions of weakness 52 which 
facilitate resilient deformation between the configurations shown in FIG. 
3 and FIG. 5. 
Referring now to the embodiment shown in FIGS. 10 and 11, the body of the 
device is in the form of a single incomplete annular ring 54 provided with 
a plurality of radially outwardly angled pairs of flaps 56. Each pair of 
flaps defines a portion of the recess 30 therebetween. 
A fifth embodiment of invention is shown in FIG. 12 to 14. This embodiment 
is similar to those previously described except the distal portions 40 of 
each of the arms 34, which remain external the eye during use, are angled 
slightly downwardly towards the eye surface to prevent the device from 
tilting towards the cornea when the arms are pressed downwards. To allow 
easier suturing, the gripping formations 44 are each provided with a 
pre-formed suture hole 54 which is adapted to receive suture thread 
therethrough. 
When viewed in plan, the arms 34 are angled slightly outwardly from the 
incision which, in addition to the downward angling, provides extra 
clearance for instruments passing through the incision. Also, the shape of 
the arms allows the device to maintain a snug fit with the eye when in use 
dilating the pupil. 
Additionally, as best shown in the inverted plan view of FIG. 14, the body 
28 of the device is recessed below the guide tab 36 so as to provide two 
regions of weakness 52 which facilitate flexure of the device into the 
elongated position described previously. 
Further, to enhance the withdrawal of the device, the proximal portion 38 
of each of the arms 34 is provided with a smoothly tapered surface 56. 
This lessens the likelihood of the device snagging or catching as the 
device is withdrawn through the incision. 
Referring back to FIG. 2, there is shown a tunnel incision 42 used in, for 
example, a lens replacement. The circumferential incision begins generally 
just behind the limbus 17, is 2.5 to 5.5 mm wide, and extends normally 
into the sclera for about half it's depth (approximately 0.5 to 0.75 mm). 
The incision then travels through the sclera and then cornea for 
approximately 3 to 4 mm then again is angled through the cornea to finally 
open into the anterior chamber 12. 
In use of the device, the incision 42, of approximately 2.5 to 5.5 mm in 
width, is made through the cornea and/or sclera of the eye. The device 26 
is then elongated or folded so that it can more easily be passed through 
this tunnel incision into the anterior chamber 12 of the eye. The device 
may be inserted in the elongated configuration by forceps such as angled 
"McIntyre" forceps. The forceps grip the device in recess 30 and so 
elongate the device for passing it through the incision. The guide tab 36 
aids the insertion process. 
Preferably, the anterior chamber is filled with a visco-elastic fluid prior 
to insertion of the device. As the device is being passed through the 
incision, the inner peripheral edge 22 of the iris is partially located in 
recess 30. This location is helped by guide tab 36 sliding over, and 
resting upon, the upper surface of the iris. The guide tab 36 also 
prevents the device from "falling" through the pupil opening during 
insertion. 
Once through the incision the resilience of the device then returns it to 
the substantially circular configuration shown in FIG. 3. As the device 
filly engages edge 22 in recess 30 it provides sufficient radial force to 
expand the iris, thus dilating the pupil. This radial force is also 
sufficient to maintain the pupil in the dilated state shown in FIG. 2. 
It will be appreciated that due to the small size of both the device and 
the iris, that occasionally some misengagement may occur which can be 
corrected by repositioning the device using arms 34. As a portion of each 
arm remains external to the eye during pupil dilation, this repositioning 
can readily be effected. Also, the surgeon can give additional dilation to 
the eye by pushing the arms towards the eye centre. Since the proximal and 
distal portions, 38 and 40 respectively, are offset axially from one 
another, the device can easily be positioned parallel to, and adjacent 
with, the iris edge after the proximal portions have passed through the 
incision in the eye. The surgical incision is generally offset so as to be 
above the plane of the iris edge. 
The apparatus according to the invention provides several major advantages 
over existing methods of dilating pupils. The first is that it will dilate 
and hold in a dilated position a pupil that would not otherwise dilate 
under the influence of eyedrops and the like. This gives the surgeon the 
space needed to perform the eye operation without having to resort to more 
drastic measures to dilate the pupil. Moreover, since the device is 
introduced into the anterior chamber of the eye by a single incision, 
there is minimal surgical trauma to the patient. 
Another advantage is that the device can be introduced through the usual 
incision made for surgery. This allows the device to be used without any 
additional incisions being made in the patients eyes. The incision may 
have to be made slightly wider than normal to fit both the arms and also 
tools such as a phaco-emulsifier simultaneously through the incision. 
A further advantage provided by the device according to the invention is 
that whilst maintaining the pupil in the dilated state, the device serves 
to effectively guard the delicate edge of the iris against unintentional 
contact with surgical instruments. 
A yet further advantage of the device of the invention is provided by arms 
34 remaining partially external to the eye whilst the device is being 
used. This allows easy re-positioning of the device and, more importantly, 
allows removal of the device generally without introducing any surgical 
tools into the anterior chamber. This greatly reduces the risk of damaging 
the eye during surgery. Additionally, formations 44 provide a convenient 
gripping point for a surgeon removing the device and also allow the device 
to be sutured in the correct position whilst an operation is performed. 
This can be important when surgical tools are continually being passed in 
and out of the incision which may otherwise accidentally move or dislodge 
the device. 
For reasons of convenience and sterilisation, the device will preferably be 
disposable. 
The device can be manufactured in many sizes to cater for varying eye sizes 
including, for example, animal eyes. 
A sixth embodiment of the invention is shown in FIGS. 15 to 21. This 
embodiment is similar to those previously described except the distal 
portions of each of the positioning arms 34 which remain external to the 
eye during use include a hinged bridge arrangement 62 pivotally connected 
via weakened portions 64 to each arm. Another weakened portion 60 is 
provided in the center of the bridge arrangement 62. When the arms are 
drawn towards each other to form the elongate or folded configuration 
needed for insertion into the eye the bridge arrangement 62 prevents the 
arms 34 from crossing over one another in a scissor action This allows the 
surgeon to maintain more control over the positioning of the device during 
insertion and removal. As in the fifth embodiment, the positioning arms 
are angled slightly downwardly towards the eye surface to prevent the 
device from tilting towards the cornea when the arms are pressed 
downwardly. Preformed suture holes 54 are provided for easier suturing. 
From the above, it will be appreciated that the device according to the 
invention represents significant improvements over the previously used 
techniques and devices for dilating a pupil and maintaining it in a 
dilated state. 
Although the invention has been described with reference to specific 
examples, it will be appreciated by those skilled in the art that the 
invention may be embodied in many other forms.