Richard S. Hoffman, MD
|
Although advancements in IOL designs and management of intraoperative zonular weakness with capsular tension rings have improved
our ability to remove cataracts and implant IOLs within the capsular bag successfully, IOL subluxation is still an occasional
problem in some patients.
Mark Packer, MD, FACS
|
Management of these cases is intimidating to most ophthalmologists but can be easily addressed with a few important principles
and simple skills.
I. Howard Fine, MD
|
Depending on the presentation of IOL subluxation, different approaches will be undertaken to resolve the malposition. IOL
decentration can be divided into four different categories: decentration within the capsular bag, subluxation outside of any
appreciable capsular support, IOL and capsular bag subluxation approachable from the anterior segment, and IOL dislocation
onto the retina.
IOL decentration within the capsular bag
When faced with a symptomatic patient with concomitant IOL decentration and posterior capsule opacification (PCO), it can
be difficult to determine which pathology is responsible for the patient's visual symptoms. It is of utmost importance not
to treat the posterior capsule with YAG laser if doubt exists as to which factor is creating symptoms, since an open posterior
capsule makes future lens repositioning extremely hazardous. When in doubt, first reposition the IOL and then perform the
YAG treatment.
Recentration can be accomplished quite easily by using a combination of viscodissection and blunt dissection with the viscoelastic
cannula through two or three paracenteses.1 The first paracentesis is placed in a location that allows for easy access to the anterior capsule where it overlies a large
portion of the IOL. Only a small amount of viscoelastic is placed in the anterior chamber to allow room for the capsular bag
to be inflated. The cannula is then slipped between the anterior capsule and the lens optic, and chondroitin sulfate and sodium
hyaluronate (Viscoat, Alcon Laboratories) is injected to dissect the capsule from the lens and the posterior capsule. Additional
paracenteses are placed to gain access to 360 of the capsular fornices.
Figure 1 (A) Combination viscodissection and blunt dissection of fibrosed capsular bag containing severely decentered PMMA
IOL 3 years following initial implantation.
|
The anterior and posterior capsules are commonly stubbornly adherent to each other where the anterior rhexis edge comes in
contact with the posterior capsule away from the decentered optic. In these locations, blunt dissection utilizing broad side-to-side
sweeping motions with the Viscoat cannula in combination with viscodissection is effective in separating the capsules (Figure
1A). Once the capsular fornices have been inflated with viscoelastic, the IOL can then be easily rotated and repositioned.
The Viscoat is then removed with bimanual irrigation and aspiration.
Figure 1 (B) Immediate postoperative appearance (note dense PCO and phimosed anterior capsulorhexis).
|
Once the lens has been recentered, future decentration is very unlikely since lens epithelial cell metaplasia and fibrosis
have already been completely exhausted. A YAG capsulotomy is usually performed 1 to 2 weeks following repositioning. This
technique is very easy to perform and in at least one case was successful in reopening the capsular bag and repositioning
a decentered IOL 3 years after the initial cataract procedure (Figure 1B).
When performing any IOL repositioning procedure, it is important to turn the microscope light down to the lowest illumination
and angle the scope away from the macula. Keep in mind that if the initial IOL calculations were correct, light from the scope
will be focused precisely on the retina, and macular burns can occur in a relatively short time if proper precautions are
not taken. When IOLs are sutured to the iris or sclera, a corneal shield is effective in reducing light toxicity during maneuvers
that do not require anterior chamber visualization.
IOL subluxation without capsular support
Figure 2 (A) Sunsetting foldable posterior chamber IOL.
|
When IOLs are placed in the ciliary sulcus and sublux (Figure 2A), the options for recentration include removal and exchange
with an anterior chamber IOL, scleral fixation, or iris fixation. Iris fixation is the simplest, quickest, and least invasive
means of dealing with these cases and can ordinarily be performed through two stab incisions.
The first incision is made with a 1.2-mm keratome and is located approximately 2 clock hours away from the end of the lens
haptic. The incision should be directed tangential to the limbus toward the haptic location. A small quantity of viscoelastic
is injected into the anterior chamber near the cornea to protect the endothelium from inadvertent trauma from the lens optic.
The viscoelastic cannula can then be used to inject a small quantity of viscoelastic behind the decentered optic, which is
prolapsed anterior to the pupillary plane. The haptics are left behind the iris. Optic prolapse facilitates the procedure
in two ways. First, it centers the optic during fixation and guarantees centration when the optic is replaced behind the iris.
Second, it tents the iris overlying the haptics, allowing for easier visualization of the haptics during suturing.
Figure 2 (B) Placement of 10-0 prolene suture through microincision, through tented iris (incorporating haptic), and out through
clear cornea.
|
Following optic prolapse, acetylcholine chloride (Miochol, Novartis) is injected into the anterior chamber to constrict the
pupil. A 10-0 prolene suture on a CIF-4 long curved needle (Ethicon) is then placed through the incision, through the peripheral
iris close to where the lens haptic is tenting the iris, underneath the haptic, up through the iris on the other side of the
haptic, and then out through clear cornea close to the limbus (Figure 2B).
Figure 2 (C) Representation of suture path following externalization of prolene loop.
|
A Siepser slip knot is then created to allow for fixation with minimal stress on the iris tissue.2 A loop of prolene suture between the iris and cornea is externalized through the incision using a Lester or Sinskey hook
(Figure 2C). The trailing end of the suture is then placed through the loop twice and by pulling on both ends of the suture,
the knot is internalized and cinched. This is repeated two additional times. The suture is then cut internally using a microincision
scissors (Microsurgical Technologies) through the small incision.
Figure 2 (D) Final appearance following stromal hydration.
|
The same technique is repeated for the other haptic through a separate 1.2-mm incision 2 clock hours away from the second
haptic. Once both haptics have been fixated to the iris, the lens optic is gently repulsed back through the pupillary plane,
behind the iris. Viscoelastic is then easily removed with bimanual I/A through the two bimanual microincisions used for suture
placement. The microincisions will seal with stromal hydration (Figure 2D).
Figure 3 Pars plana incision measured 3.5 mm posterior to limbus for limited vitrectomy and prolapse of decentered lens optic.
|
If vitreous is present in the anterior chamber prior to beginning the procedure, it is best to make an inferotemporal pars
plana incision with a 20-gauge MVR blade 3.5 mm posterior to the limbus for a limited vitrectomy (Figure 3). The vitrector
or spatula can then be used through the pars plana incision to prolapse the optic through the pupil for iris fixation.
Subluxation of IOL and capsular bag complex
Figure 4 (A) Subluxed IOL within subluxed capsular bag in patient with pseudoexfoliation.
|
In instances where the IOL is subluxed and remains within a displaced capsular bag, the options for surgical correction can
be more complex. Suture fixation to the iris is complicated by an inability to prolapse the lens optic through the pupil.
The diameter of an intact lens/capsule complex would require removing the IOL from the capsular bag in order to perform this
maneuver. Although it is possible to sew the haptic and capsule to the iris using tenting of the haptic/capsular bag complex
by means of a second instrument through a pars plana approach, this is a somewhat challenging maneuver.
When presented with a subluxed IOL within a subluxed capsule (Figure 4A), it is more straightforward to perform scleral fixation.
There have been numerous excellent techniques published for suturing dislocated IOLs to the sclera. A simple approach involves
the use of 10-0 or 9-0 prolene suture on a double-armed long STC needle (Ethicon).3
Figure 4 (B) Docking of STC needle (prolene) from clear corneal incision (above) into 27-gauge needle passed behind haptic
and through capsular bag.
|
With this technique, two 3 3 mm scleral tunnel incisions are created 180 apart from each other in a meridian that is aligned
with the visible haptic end of the subluxed IOL. Two stab incisions are then made in the peripheral clear cornea anterior
to each of the scleral tunnels. An additional 1.2-mm clear corneal incision can be made to the right-hand side to utilize
an intraocular micrograsper (Microsurgical Technologies) to aid in suture needle placement if needed. The anterior chamber
is then half-filled with Viscoat.
Figure 4 (C) Iris hook retracts iris as micrograsper (right side) aids in externalization through 27-gauge needle.
|
Attention is directed initially to the centrally exposed haptic. A 27-gauge needle is passed through the scleral tunnel incision,
penetrating the scleral bed 1 to 1.5 mm posterior to the limbus. The needle is then passed behind the haptic and through the
capsular bag. The double-armed prolene suture is passed through the opposite clear corneal paracentesis, taking care to enter
through the incision without passing through corneal stromal tissue. The suture needle is then docked into the 27-gauge needle
(Figure 4B) and both are simultaneously removed from the stromal tunnel incision. This maneuver is then repeated passing the
27-gauge needle through the scleral tunnel incision and through the scleral bed approximately 1 to 2 mm adjacent to the first
external pass. The needle is then oriented above the haptic and capsular bag. The second arm of the double-armed prolene suture
is then passed through the opposite paracentesis, docked into the 27-gauge needle, and passed through the eye wall as before.
Tying of this prolene suture will recenter the IOL and the knot will bury under the roof of the scleral tunnel incision.
Figure 4 (D) Immediate postoperative appearance. (Figures courtesy of Richard S. Hoffman, MD, Mark Packer, MD, and I. Howard
Fine, MD)
|
Orientation of the 27-gauge needle is simple for the initial haptic secondary to the improved visualization from the IOL decentration.
Visualization and suturing of the second "hidden" haptic can be facilitated by placement of a single iris hook through the
paracentesis previously utilized for the first suture placement. The maneuver is repeated for the second haptic in the same
manner, passing each arm of the prolene suture above and below the lens haptic using the 27-gauge needle through the second
tunnel incision to aid in proper placement. Docking and exiting of the straight STC prolene needle can be facilitated by use
of an intraocular micrograsper inserted and utilized through the right-handed 1.2-mm microincision (Figure 4C) Viscoelastic
can then be removed using bimanual I/A through two of the three clear corneal incisions. No suture placement is needed for
the scleral tunnel incisions and overlying conjunctival peritomies can be closed with cautery or 8-0 Vicryl (Figure 4D).
IOL dislocated onto retina
When IOLs dislocate completely onto the retina, a pars plana vitrectomy and IOL repositioning are generally coordinated with
a retina specialist. Numerous publications have described techniques for scleral fixation of dislocated IOLs. The least invasive
approach for these cases is iris fixation after the lens optic has been prolapsed through the pupil as previously described.
If the dislocated IOL is a one-piece plate-haptic IOL, the lens is usually explanted and replaced with a foldable IOL that
is iris fixated.
Final comments
The majority of cases of IOL subluxation will involve mild to moderate decentration within an intact and centered capsular
bag. Instances of dislocated IOLs without capsular support or subluxed IOL/capsular bag complexes are rarer but may become
more common in the future as previously treated pseudoexfoliation and traumatic cataract cases mature.4-6
Although they may seem intimidating cases to approach, repair and recentration of decentered and subluxed IOLs is easily within
the skills of the average anterior segment surgeon. Most important when proceeding with these cases is to avoid macular phototoxicity
and reposition the IOL first before performing a YAG capsulotomy in instances of symptomatic IOL decentration with concomitant
PCO.
Regardless of whether the IOL is decentered within a normal capsule or subluxed without any capsular support, restoration
of a normal lens position can be achieved under most circumstances through two or three microincisions without the need for
lens exchange or large incisions.
Richard S. Hoffman, MD, is co-editor of Cataract Corner
. He is clinical associate professor of ophthalmology at Oregon Health & Science University, Portland, and is in private practice
in Eugene with Drs. Fine, Hoffman & Packer.
Mark Packer, MD, FACS, is co-editor of Cataract Corner
. He is assistant clinical professor of ophthalmology at Oregon Health & Science University, Portland, and is in private practice
in Eugene with Drs. Fine, Hoffman & Packer.
I. Howard Fine, MD, is clinical professor of ophthalmology at Oregon Health & Science University, Portland, is a founding member of the Oregon
Eye Associates, and is in private practice in Eugene with Drs. Fine, Hoffman & Packer.
References
1. Fine IH, Hoffman RS. Late reopening of fibrosed capsular bags to reposition decentered intraocular lenses. J Cataract Refract
Surg 1997;23:990-994.
2. Chang DF. Siepser slipknot for McCannel iris-suture fixation of subluxated intraocular lenses. J Cataract Refract Surg
2004;30:1170-1176.
3. Moreno-Montanes J, Heras H, Fernandez-Hortelano A. Surgical treatment of a dislocated intraocular lens-capsular bag-capsular
tension ring complex. J Cataract Refract Surg 2005;31:270-273.
4. Ahmed II, Crandall AS. In-the-bag intraocular lens dislocation. Am J Ophthalmol 2005;139:952-953.
5. Masket S, Osher RH. Late complications with intraocular lens dislocation after capsulorhexis in pseudoexfoliation syndrome.
J Cataract Refract Surg 2002;28:1481-1484.
6. Jehan FS, Mamalis, Crandall AS. Spontaneous late dislocation of intraocular lens within the capsular bag in pseudoexfoliation
patients. Ophthalmology 2001;108:1727-1731.
