The treatment of ectopia lentis with inadequate intraoperative pupil mydriasis requires top-notch surgical skill.1 Potential treatment strategies include cataract surgery with the application of iris retractor hooks. Depending on the number of iris hooks, a pupil of various diameters may be achieved, but in a triangular, diamond, or square shape.2 Moreover, the technique requires redundant corneal incisions, while the multiple extraocular peripheral parts of the iris retractors may be an obstacle for the laser docking resulting in an unstable anterior chamber depth and increasing the risk of infection.3
Use of a femtosecond laser has been previously described as a precise reproducible method for circular capsulotomy formation4 and may be of benefit in cases of zonular insufficiency associated with lens subluxation.5
In this technique report, we describe a new method to be used for an inadequately dilated pupil and ectopia lentis. A pupillary expansion ring is first positioned centrally to dilate the pupil and subsequently repositioned by pulling the ring in the axis corresponding to the lens location. It is then fixated by sewing one of the ring coils to the corneal limbal area with a single temporary knot. A femtosecond laser is then used to create the anterior capsulotomy followed by phacoemulsification and intraocular (IOL) implantation (Figure 1).
After sterile preparation and placement of the lid speculum, a 2.0 mm clear corneal incision (CCI) is made with a disposable stainless steel calibrated blade. The anterior chamber is filled with a highly dispersive ophthalmic viscosurgical device (OVD) (sodium hyaluronate 3.0%–chondroitin sulfate 4.0% [Viscoat]). A pupillary expansion ring (Malyugin Ring 2.0, Microsurgical Technology, Inc.) with a 6.25 mm or 7.00 mm diameter is inserted using an injector. After the coils of the device engage the iris pupillary margin, the expansion ring is rotated toward the coil located in the meridian corresponding to lens subluxation. A double-armed 10–0 polypropylene suture (Mani, Inc.) is used to fixate the ring to the limbus.
One needle is placed through the main incision (or paracentesis) located at least 90 degrees from the point of the future needle exit and passed through 1 of the pupillary expansion ring coils located in the meridian of the lens displacement. The needle is then passed though the limbal area out of the eye. The second needle of the same suture is placed in the same wound and passed, in the same manner, above the scroll of the pupillary expansion device, exiting the anterior chamber in the same meridian but slightly superior to the first suture pass. This is done to prevent rotational movement of the pupil expander that can result from placing the second needle below the point of exit of the first needle.
By pulling both sutures with a toothless forceps, the pupillary expansion ring is displaced in the direction of the suture exit from the anterior chamber to the point at which the center of the pupil and the center of the expansion device are corresponding with the center of the ectopic lens. Both needles are cut and the suture ends tied temporarily outside the eye to fixate the pupil diaphragm in the desired position. The anterior chamber is then refilled with the dispersive OVD and the corneal wound(s) checked to be watertight. If a CCI of 2.0 mm is not long enough to secure the self-sealing ability of the wound, a single 10–0 nylon suture is used to temporarily close the wound during femtosecond laser application.
Under sterile conditions, the suction ring of the femtosecond laser is aligned according to the corneal limbus and attached to the eye and vacuum is applied. The surgical microscope head is moved aside and the laser head docked to the suction ring. The laser capsulotomy diameter is adjusted from 3.5 mm to 4.8 mm depending on the size of the lens and the degree of its displacement. On request, the manufacturer slightly modified the laser software to accept wider variations of pupil eccentricity.
Laser parameters for capsulotomy are 110% power with 50.0 mm per second speed and for lens fragmentation, 125% power with 10.0 mm per second speed. From 0 up to 6 radial cuts are used to fragment the lens nucleus depending on its hardness. No corneal incisions are made with the laser.
After the laser anterior capsulotomy and lens fragmentation was performed, vacuum is released and the suction ring along with the laser head is removed.
The circular anterior capsule fragment is removed with a Seibel microcapsulorhexis forceps (Microsurgical Technology, Inc.). The capsulotomy is completed with a microcapsulorhexis forceps following the circular contour of the capsulotomy opening created by the laser.
Subsequent steps of the procedure include releasing and removing the temporary suture holding the pupillary expansion ring in its decentered position and placing up to 3 capsule retractors (Microsurgical Technology, Inc.) to suspend the capsular bag and support the weak zonular apparatus. Once hydrodissection, ultrasound phacoemulsification, and lens cortex irrigation/aspiration are complete, all capsule retractors except 1 are released and removed. Next, a Malyugin-modified Cionni capsular tension ring (type 10G, Morcher GmbH) with a preplaced 9–0 polypropylene suture (Mani, Inc.) through the fixation element eyelet is implanted in the bag with an injector.
A highly viscous OVD bolus is injected under the iris to expand the ciliary sulcus by lifting the iris root, and the suture needle is passed though the ciliary sulcus, exiting the eye approximately 1.5 mm from the limbus.
A zigzag suturing technique is used to fixate the 9–0 polypropylene suture to the sclera.6 The last capsular hook is released from the capsular bag and removed from the eye. A 3-piece or 1-piece hydrophobic acrylic IOL is implanted in the capsular bag. At the completion of the procedure, the pupillary expansion ring is disengaged from the iris and removed from the anterior chamber with the help of a proprietary insertion device.
Video 1 (available at http://jcrsjournal.org) shows the proposed surgical technique in an eye with post-radial keratotomy (RK) radial corneal scars, lens subluxation, nuclear cataract, and pseudoexfoliation syndrome (PXF).
The technique was used in 3 patients with Marfan syndrome and 1 with PXF; in the later case, post-RK radial corneal scars and several residual capsule tags were identified. All patients were scheduled to have femtosecond laser–assisted cataract surgery with the Femto LDV Z8 (Ziemer Ophthalmic Systems AG). The study was approved by the Ethics Committee, Humanitas Clinical and Research Center, and performed according to the tenets of the Declaration of Helsinki. The patients were informed of the risks and benefits associated with the surgical procedure before signing informed consent.
The patients presented to S. Fyodorov Eye Microsurgery Institution with lens subluxation of different grades (ie, SubN1 and SubT1) according to the Chandra et al. classification system.7 The visual acuity (CDVA) varied from 20/70 to 20/200, respectively.
The anterior chamber in all cases remained intact, with no clinically significant flattening despite the required manipulation (Figure 2). In 1 case, there was bleeding from the limbal blood vessels into the anterior chamber after 1 of the needles was passed. This was managed by tamponade with OVD by injection into the anterior chamber temporarily increasing the intraocular pressure. No other complications occurred during or after the surgery.
All patients had improved uncorrected distance visual acuity and CDVA. Patients were followed for 6 months postoperatively. The IOLs were well centered and remained stable in the capsular bag.
Ectopia lentis is congenital or acquired in origin, occurring spontaneously secondary to trauma or associated with a rigid iris diaphragm.1,6 The degree of lens dislocation from the pupillary axis varies from minimal to bisecting of the pupil with its margin to total dislocation into the anterior chamber or vitreous cavity. Capsular bag instability resulting in zonular insufficiency is frequently a concurrent pathology. All these pathologies lead to formation of a cataract and visual impairment.
Cataract surgery in cases of lens decentration remains a challenging procedure that requires a high level of surgical skill and experience.8,9 Anterior curvilinear capsulorhexis is thought to be one of the most challenging steps of cataract surgery in eyes with subluxated lenses because the lack of capsular tension by zonular fibers hampers the initiation and propagation of the tear. Thus, femtosecond laser creation of the capsulotomy has been suggested to facilitate the step in these cases.5,10 The laser is applied when the globe is intact, providing a stable intraocular environment. In addition, the laser energy is applied to the capsule in a timeframe of milliseconds and does not lead to even minimal lens displacement.
Theoretically, alternative technologies such as the Zepto nanopulse capsulotomy system (Mynosis Cellular Devices, Inc.), which has the advantage of avoiding tangential traction during capsule opening, might be beneficial for subluxated lens cases provided there is sufficient residual zonular support to allow pressure on the lens during the device placement and vacuum fixation to the anterior capsule. The use of ultra-high-viscosity OVD might be helpful in stabilizing the lens in these eyes.11
In our case series, the capsulotomy size was chosen to be smaller than that usually performed in femtosecond laser–assisted cataract surgery for uncomplicated cataracts to avoid its placement close to the equator of the lens. Preservation of a sufficient capsule rim is necessary to secure the IOL safely inside the capsular bag.
A capsulotomy that is too small might be challenging during subsequent surgical maneuvers, increasing the risk for anterior capsulotomy edge damage during lens fragmentation and evacuation, a complication not seen in our series. Younger patients with thick and very elastic capsules have a tendency toward the resulting size to be larger than the size selected on the laser, a phenomenon well known to pediatric cataract surgeons. For PXF patients, however, the surgeon should aim for the biggest anterior capsulotomy possible to prevent intraoperative issues and to deter subsequent capsule phimosis leading to late capsular bag–IOL complex decentration.
The use of femtosecond laser–assisted cataract surgery for corectopia, in which the ectopic pupil was centered on the lens by fixing 1 of the pupillary expansion ring sides with an iris retractor, has been described.3 The main concern with this surgical technique is that the tail of the iris hook protruding beyond the cornea can result in an ocular surface and laser interface discrepancy. This can cause suction loss during femtosecond laser–assisted cataract surgery and possible elevation of the iris diaphragm right after the compression of the external part of the iris hook that is positioned outside the eye.
By using the temporary suturing technique rather than iris hooks to position the iris diaphragm to the desired location can exclude these risks. We acknowledge that fixation of the ring coil to the limbus is a critical part of the procedure. In all our cases, the ring coil was sutured after ring implantation. This step was uneventful because the coil has a reasonably wide gap, allowing the needle to be passed without significant difficulty. However, preplacing the suture before ring injection into the anterior chamber might be a viable option to avoid excessive intracameral maneuvers.
Critical to ensuring that the suture looping around the strand forming the coil will not cause rotational movement when is tied outside of the eye, the needle that passes above the coil must exit superior to the first.
Passing the needle through vascularized tissue (ie, corneal limbus) may lead to bleeding. This is very much dependent on 2 factors: (1) thickness and density of the blood vessels in the limbal area that may vary individually and (2) the direction of the suture pass and its proximity to the sclera. We do not believe any specific precautions are necessary while using the proposed technique.
In conclusion, this new technique for small pupils associated with ectopia lentis has the potential to improve surgical results by allowing the anterior capsulotomy to be created with the femtosecond laser, thus increasing the precision of the capsulotomy and minimizing possible complications in the selected cases.
WHAT WAS KNOWN
- Femtosecond laser capsulotomy and lens prefragmentation in patients with ectopia lentis reduces the mechanical stress on the lens capsule and zonular apparatus caused by cataract extraction.
- The pupillary expansion ring is useful, allowing for safe and effective mechanical pupil expansion in eyes with insufficient mydriasis.
WHAT THIS PAPER ADDS
- The use of the pupillary expansion ring in patients with ectopic lenses and insufficiently dilated pupils provides simultaneous pupil expansion and displacement. This is achieved by temporarily suturing the device to the limbal area, allowing the capsulotomy created by the laser beam to be centered corresponding to the center of the displaced lens.
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Disclosures:Dr. Malyugin receives royalties from Microsurgical Technology, Inc. and Morcher GmbH. Dr. Arbisser is a consultant to and stockholder in Mynosys Cellular Devices, Inc. None of the other authors has a financial or proprietary interest in any material or method mentioned.