Sutured Posterior Chamber Lenses: Indications and Techniques

David R. Hardten, MD

Introduction

IOL implantation is an effective form of visual rehabilitation at the time of cataract extraction. However, IOLs also benefit patients who originally underwent cataract extraction without a lens implant and are now intolerant of spectacles or contact lenses. Studies have been published comparing the visual outcome and complications of anterior chamber intraocular lens (ACL) implantation with posterior chamber intraocular lens (PCL) implantation as a secondary procedure in aphakic patients.^1-5 Controversy exists as to the preferred location for the implant. Although many researchers believe that secondary PCL insertion may be preferred to secondary ACL insertion,⁶ some studies suggest that the efficacy and complication rates of the two procedures may be similar.⁴ Because of the ease of the surgical procedure, ACL insertion remains the technique of choice for many surgeons.⁷ However, cases in which there is no capsular or angle support may require implantation of a PCL.

The potential advantages of a PCL over an ACL include decreased risk of corneal edema,^1,3-5 endothelial cell loss,³ secondary glaucoma,^1-5 cystoid macular edema (CME),^1-3,5 inflammation with fibrinous membrane formation,³ pupil capture,⁵ and uveitis-glaucoma-hyphema syndrome.⁴ Other theoretical advantages of PCLs over ACLs include decreased incidence of peripheral anterior synechiae, angle fibrosis, and iris chafing.⁸ For these reasons, insertion of a PCL is a good choice for secondary lens implantation in an aphakic patient. In this tutorial, the current technique for secondary PCL implantation in cases of inadequate capsular support will be described.

Preoperative Evaluation of Aphakic Patients

Uncorrected aphakia may cause significant functional disability. A patient who is most likely to benefit from secondary lens implantation is an aphakic patient who is spectacle and contact lens intolerant. In all cases, an attempt at visual rehabilitation with aphakic spectacles or contact lenses should be made because of the potential risks of secondary lens implantation. In binocular aphakia, the patient may be able to tolerate spectacles reasonably well. However, in cases of unilateral aphakia, spectacles are not an option because of anisometropia and the resultant aniseikonia. In this situation, an attempt should be made to fit a soft or rigid gas permeable contact lens in the aphakic eye. Relative or absolute contraindications to contact lens wear include giant papillary conjunctivitis, dry eye syndrome, blepharitis, lagophthalmos, a large filtering bleb, difficulty with lens insertion or removal, and a history of contact lens-related corneal complications such as infectious keratitis, corneal edema, or neovascularization. Secondary PCL implantation is a reasonable option in these cases. The functional disability interfering with patient lifestyle and the inability to tolerate spectacles or contact lenses should be adequately documented in the chart.

Caution should be exercised in implanting a secondary PCL in patients with a history of retinal detachment, chronic CME, chronic uveitis, glaucoma, or borderline corneal endothelial cell counts. Lens placement may be associated with retinal detachment^2,4,8-11 or CME^4,5,8-11 and may be relatively contraindicated in patients with chronic uveitis.¹² Secondary postoperative glaucoma may worsen a preexisting glaucomatous condition.^4,5,8,11,13 A low endothelial cell count (less than 1,000 cells/mm²) may be a relative contraindication to secondary lens placement. Any anterior segment intraocular procedure may result in loss of endothelial cells with resultant corneal edema or need for penetrating keratoplasty.¹⁴ Endothelial cell loss can be as high as 26% in patients undergoing cataract extraction or lens implantation.¹⁵ More than 60% of patients undergoing PCL insertion lose at least 10% of their endothelial cells.³ This loss of endothelial cells may increase the risk of postoperative corneal failure.

Patients who are considered for secondary lens placement should undergo a complete ocular history and examination. As part of the ocular examination, a careful refraction and determination of best-corrected visual acuity should be undertaken in both the operative and nonoperative eyes. A careful anterior segment biomicroscopic examination should be performed, with particular attention paid to corneal clarity, the integrity of the hyaloid face and posterior capsule, the corneal endothelium, the anatomy of the iris, the presence or absence of capsular support, and the location of the vitreous. Examination of the anterior sclera should be performed to rule out scleral ectasia, especially in patients who are highly myopic or have rheumatoid arthritis. In addition, gonioscopy and evaluation for glaucoma risk factors are important.

The ocular examination should also include careful inspection of the posterior segment of the eye to rule out CME or other fundus pathology. If CME or other retinal pathology is suspected based on clinical examination, fluorescein angiography should be performed. If risk factors for retinal detachment such as lattice degeneration or a retinal tear are identified on the preoperative peripheral retinal exam, prophylactic treatment should be considered.¹⁶ Appropriate additional testing prior to secondary PCL placement includes endothelial cell counts and morphology, corneal pachymetry, and IOL power calculations.

Other Indications

Preoperatively, it may be possible to predict the need for a sutured PCL in patients with loose zonules from Marfan syndrome, trauma, or pseudoexfoliation syndrome. In these patients, the preoperative examination should be performed as in an aphakic patient because a complete understanding of the anatomy is important in surgical planning. In many cases, the decision to implant a sutured PCL may have to be made intraoperatively if the posterior capsule is torn and there is inadequate support for a sulcus-fixated IOL.

Informed Consent

Documenting informed consent from the patient and the family is one of the most important aspects of the preoperative evaluation. The decision to proceed with surgery is complex, involving both the patient and surgeon. A thorough discussion of potential benefits, alternatives, and risks of the procedure must be undertaken with the patient and family prior to performing the surgery. The patient must be informed of the risk of best-corrected visual acuity loss from potential complications such as chronic CME and retinal detachment.

Surgical Procedure

Two of the most important factors in planning surgery are the adequacy of capsular support andidentification of the location of the incision site. A candidate for secondary PCL implantation will have undergone either intracapsular cataract extraction (ICCE) or extracapsular cataract extraction (ECCE). In a patient who has undergone ECCE with an intact anterior and posterior capsule, the secondary PCL may be placed directly in the ciliary sulcus without suture fixation. However, secondary lens insertion is more common after ECCE when intraoperative complications such as a posterior capsular tear, a radial anterior capsule tear, zonular disruption, and/or vitreous loss have occurred. In these situations, determination of the adequacy of capsular support is critical for surgical planning. If adequate capsular support post-ECCE is not available or if the patient has undergone ICCE, a transscleral suture fixation technique for placement of the secondary PCL is preferred. Despite careful preoperative planning, the adequacy of capsular support may need to be determined intraoperatively.

Slide 1

Determination of the best location for the scleral incision site and transscleral suture placement mainly depends upon preoperative astigmatism. The incision site should be placed at the meridian of greatest preoperative cylinder as determined by refraction, keratometry, or computerized videokeratography. With time, the astigmatic power at the meridian of a corneoscleral incision tends to lessen.¹⁷ Therefore, the best location for the incision in patients who have with-the-rule astigmatism is at the 12 o'clock meridian (Slide 1). Conversely, patients with against-the-rule astigmatism should have the incision centered at the 180° meridian at the temporal limbus. In patients with significant amounts of preoperative cylinder (> 2 D), astigmatic keratotomy with transverse corneal incisions may be performed intraoperatively or as a separate procedure postoperatively when the refraction and keratometric readings have stabilized.¹⁸

Anatomic factors that may influence placement of transscleral sutures include the location of filtering blebs, scleral thinning, and ciliary nerves and vessels. Scleral thinning could allow the suture to erode and cause dislocation of the PCL. Transscleral sutures should be placed in an oblique meridian to avoid the long, posterior ciliary nerves and arteries. The incision is usually centered at 12 o'clock and the transscleral sutures are placed at 2 o'clock and 8 o'clock in patients who have with-the-rule astigmatism.

Preoperative surgical planning for secondary PCL placement requires careful consideration of the adequacy of capsular support, the location of the incision, and the location of transscleral suture placement.

IOL Selection

In the case of secondary PCL placement with adequate capsular support, a one-piece, all-PMMA lens with a 6.5-mm or 7-mm diameter optic is recommended. The rigidity of the one-piece design offers the advantage of stability in the ciliary sulcus. The large optic minimizes edge glare if the lens migrates postoperatively.

A preferred option for secondary sewn-in PCL insertion in cases of inadequate capsular support is a large diameter, one-piece, all-PMMA lens with eyelets 180° apart on the inside surface of each haptic. The diameter of the optic should be either 6.5 mm (e.g., P366UV, Bausch & Lomb Inc., Claremont, Calif.) or 7 mm (e.g., CZ70BD, Alcon Surgical, Fort Worth, Texas). The 7-mm optic size should be considered in cases of IOL exchange or secondary placement when combined with penetrating keratoplasty since the larger optic can easily fit through the large open-sky wound. The 6.5-mm optic may be preferred when a lens is inserted through a corneoscleral incision. With transscleral suture fixation, the rigidity of the one-piece design minimizes the chance of migration or subluxation compared to a three-piece design in which the haptics are less stable. The large optic minimizes the risk of edge glare when the lens is not centered perfectly at the time of surgery or becomes decentered postoperatively, or the iridoplasty does not completely cover the lens edges. The eyelets prevent migration of the suture along the haptics and ensure that the sutures are attached to the haptics 180° apart.

The IOL power should be computed with one of the accepted formulae using keratometric values and axial length as determined by A scan ultrasonography.¹⁹ The appropriate lens power for the goal postoperative refractive error is then selected based on the patient's visual needs.

Secondary PCL Placement without Adequate Capsular Support

General or local anesthesia may be used during secondary PCL placement, depending on the general medical status of the patient and surgeon preference. If a retrobulbar or peribulbar block is given, post-block compression may be performed to enhance distribution of the anesthetic. Consideration should be given to the use of preoperative osmotics to decrease vitreous volume and soften the eye. The pupil is dilated with three applications consisting of 1 drop of phenylephrine hydrochloride 2.5% and 1 drop of cyclopentolate 1% every 5 minutes 1 hour before the procedure. The patient also receives three applications consisting of 1 drop of an antibiotic/steroid combination and 1 drop of a topical nonsteroidal in the preoperative area. These drops are used to prophylax against bacterial infection, minimize postoperative inflammation, and augment intraoperative pupillary dilation.

Slide 2

The patient is then prepped and draped in the usual sterile manner. A wire lid speculum is inserted and a superior and inferior rectus stay suture may be placed for traction. A 12-line radial keratotomy marker dipped in methylene blue is used to mark the cornea to ensure placement of the transscleral sutures in the proper meridian 180° apart (Slide 2). If no unusual circumstances exist, such as a filtration bleb or scleral ectasia, a fornix-based conjunctival peritomy is performed for 4 clock hours centered on the axis of greatest astigmatic power. This initial peritomy should be large enough to expose bare sclera over the nearest intended transscleral suture fixation site. A second 2-clock hour peritomy is constructed 180° away from the first transscleral suture fixation site. For example, a 4-clock hour peritomy centered at the 12 o'clock meridian should be performed in a patient who has with-the-rule astigmatism in the left eye. This peritomy should be large enough to expose bare sclera at 2 o'clock for transscleral suture placement. A second peritomy would be centered at 8 o'clock for the second transscleral suture. The PCL haptics would then be fixated at 2 o'clock and 8 o'clock (Slide 2). Wetfield cautery is used to obtain hemostasis. When the conjunctival dissection is in the area of the previous cataract procedure, tissue dissection and hemostasis may be more difficult. A 67 blade can be used to clean the scleral surface.

Slide 3

A 6.5-mm to 7-mm chord length, vertical scleral groove is made 1 mm to 1.5 mm posterior to the surgical limbus to approximately 50% depth. The sclera is then dissected in a plane perpendicular to the groove incision up to clear cornea. The anterior chamber may then be entered with a supersharp or crescent blade anterior to Schwalbe's line in a direction parallel to the scleral groove, creating a three-plane mortised incision (Slide 3). This type of incision is constructed to minimize postoperative astigmatism and create a watertight closure. The initial entry into the eye should be no more than 3.5 mm in length so that a deep chamber may be maintained for possible subtotal vitrectomy.

Slide 4

In most cases, a vitrectomy will be required to allow safe placement of the lens without entrapment of the vitreous. A bimanual anterior vitrectomy is performed through the scleral flap incision with an automated suction cutter. Irrigation is provided by a second handpiece. Care should be taken to remove all vitreous from the anterior chamber. Vitreous or remnant lens material adherent to the posterior iris surface must also be cut to allow easy insertion of the lens. A light pipe is useful to identify vitreous during the vitrectomy (Slide 4). To reduce the incidence of CME, vitreous should be cleared from the wound, the iris, and areas in contact with the IOL.

Following vitrectomy, viscoelastic material is used to retroplace any remaining vitreous, reform the anterior chamber, and protect the endothelial cells during the implantation procedure. The wound is opened to its full extent, 6.5 mm to 7.0 mm. The secondary PCL is prepared for transscleral fixation by passing one end of a 3-inch, double-armed, 10-0 polypropelene suture with a long needle (Sharpoint SSL-15, JA-2559, Sharpoint, Surgical Specialties Corporation, Reading, Pa.) through the eyelet on the inferior haptic. One needle attached to this suture is grasped with a small needle holder. This needle is passed under the base of the iris and through the ciliary sulcus 0.5 mm superior to the 8 o'clock meridian. The needle should exit the sclera 0.5 mm to 1 mm posterior to the surgical limbus. The second needle on the same suture should similarly be passed under the base of the iris through the ciliary sulcus such that the needle exits 0.5 mm to 1 mm posterior to the surgical limbus. This second needle should pass approximately 0.5 mm inferior to the 8 o'clock meridian such that the two ends of the same suture exit the sclera 1 mm apart (Slide 5). A short needle on a 2-inch, 10-0 polypropelene suture (Sharpoint SSL-5, JA-2560) should be threaded through the superior eyelet. The needles attached to this suture should then be passed through the ciliary sulcus approximately 0.5 mm above and below the 2 o'clock meridian, 0.5 mm to 1 mm posterior to the surgical limbus (Slide 5). The superior and inferior transscleral fixation sutures must pass through the sclera 180° apart to ensure optic centration.

SLIDE 6

SLIDE 7

A superior peripheral iridectomy is performed if one is not already present. Following placement of the PCL, viscoelastic material is removed with the irrigation/aspiration handpiece to prevent a postoperative pressure rise. The shelved corneoscleral wound is then closed using the surgeon's standard technique, such as placing a running suture with 10-0 nylon. The conjunctiva is re-approximated with either bipolar cautery or suture. The patient then receives an injection of antibiotic and deposteroid in the inferior conjunctival fornix. A drop of beta-blocker is placed on the eye. Placing a semi-pressure patch and shield on the operative eye completes the procedure.

Postoperative Care

On the first postoperative day, the patch and shield are removed. The eye is examined for evidence of excess inflammation, hyphema, increased intraocular pressure (IOP), or wound leak. The patient is placed on an antibiotic/steroid drop for 4 to 6 weeks postoperatively. Excess inflammation is treated with increased topical steroids. A postoperative hyphema is observed closely but does not usually require surgical intervention. Increased IOP is treated with aqueous suppressants.

After the initial follow-up, the patient is seen at regular intervals as dictated by the clinical situation. Typically, a patient is seen at postoperative week 1, week 3, and week 8. The fundus is examined regularly 12 to 18 months after surgery because of the risk of postoperative retinal detachment and CME. The patient is also warned of the symptoms of a retinal break or detachment.

Postoperative Results

Reported visual results after secondary PCL insertion are excellent. Some series, however, combine results from PCLs inserted as a secondary procedure with those inserted in exchange for another IOL. Lindstrom reported that for 98 patients (combined from series by Lindstrom and associates⁹ and Mazzocco and associates¹⁰) who underwent secondary or exchange PCL implantation, 90.1% achieved best-corrected postoperative visual acuity of 20/40 or better with at least 6 months' follow-up.¹ Of these 98 patients, only 2% lost two or more lines of best-corrected acuity. Wong and associates reported that of 40 patients who underwent secondary PCL implantation followed for at least 1 year, 90% had visual acuity of 20/25 or better.² All 40 patients had improved or the same visual acuity postoperatively as preoperatively. Spigelman and associates reported the visual results of seven patients who underwent exchange or secondary PCL implantation with a transscleral suture fixation technique.²² The average best-corrected postoperative acuity in this group with at least 3 months' follow-up was 20/29.

Lindquist and associates reported that for 13 patients followed for a mean of 9.4 months who underwent secondary transsclerally fixated PCL implantation, the mean postoperative best-corrected visual acuity was 20/23.²³ Only one of these patients lost two or more lines of preoperative visual acuity, while nine patients had improvement in postoperative visual acuity compared to preoperative acuity. Hahn and associates found that 84.4% of 32 patients who underwent secondary PCL implantation had best-corrected visual acuity of 20/40 or better with mean follow-up of 10.4 months.3 Three of the five patients who had best-corrected visual acuity worse than 20/40 had undergone penetrating keratoplasty at the time of lens implantation. Lyle and Jin reported that in 114 patients without preexisting ocular pathology who underwent secondary PCL implantation, 91.4% had postoperative visual acuity of 20/40 or better with a an average follow-up of 19.5 months.⁴ These series show that secondary PCL implantation is an effective way to visually rehabilitate an aphakic patient.

Complications

Limited data are available concerning the incidence of complications with secondary PCL implantation alone because many of the complications reported are from series in which data from secondary PCL implantation alone are combined with cases in which the PCL is inserted in exchange for another IOL, or as a secondary procedure at the time of penetrating keratoplasty. Lindstrom reported that for 98 patients (combined from series by Lindstrom and associates⁹ and Mazzocco and associates¹⁰) who underwent secondary or exchange PCL implantation, complications included retinal detachment (3%), CME (2%), hyphema (1%), pupil capture (1%), pseudophacodonesis (1%), and posterior capsule opacification (1%).¹

Wong and associates reported complications of transient corneal edema (2.5%) and retinal detachment (2.5%) in 40 patients who underwent secondary PCL implantation.² In Lindquist and associates' series of 13 patients who underwent transsclerally fixated PCL implantation alone, the only reported complication was slight lens decentration in one patient (7.7%).²³ Hahn and associates reported the complications of capsular opacification (3.1%) and PCL dislocation into the vitreous (3.1%) in 32 patients who underwent secondary PCL placement.3 Lyle and Jin reported the complications of CME (6.1%), retinal detachment (3.5%), posterior capsular opacity (3.5%), lens malposition (2.6%), epiretinal membrane formation (1.8%), corneal decompensation (0.9%), glaucoma (0.9%), and endophthalmitis (0.9%) in a group of 114 patients who underwent secondary PCL implantation.⁴

Lane and associates extensively reviewed the complications reported in the literature associated with transscleral suture-fixated PCLs.⁸ The reported complications with this technique included external suture erosion, corneal transplant rejection or failure, glaucoma, peripheral anterior synechiae formation, CME, retinal detachment, hyphema, vitreous hemorrhage, suprachoroidal hemorrhage, endophthalmitis, and lens tilt, decentration, and dislocation. Solomon and associates reported complications in 30 cases of transsclerally sutured PCLs with the knot buried under a scleral flap including suture erosion through the scleral flap (73.3%), suture erosion through the conjunctiva (16.7%), new-onset, postsurgical glaucoma (6.7%), IOL tilt/decentration (3.3%), and suprachoroidal hemorrhage (3.3%).¹³ In a group of penetrating keratoplasty patients, suture knot erosion was noted in 11% of eyes.²⁴ The knot did not rotate into any of the eyes in this group. Another study showed no erosion of knots even if the knot rotated into the eye when covered by a scleral flap.²⁵

Meticulous attention to proper surgical technique may help avoid some of these complications. Retinal detachment and CME occur more commonly after vitreous loss or after vitrectomy has been performed.^2,4,26,27 For this reason, manipulation of the vitreous should be avoided if there is no vitreous in the iris plane or where the implant is to be placed. Progressive corneal edema or secondary corneal transplant failure may be minimized by the judicious use of viscoelastic material to coat the endothelium at the time of lens implantation. Touching the endothelium with needles, the lens, or instruments should be avoided. Secondary glaucoma may result from pupillary block, hyphema, or inflammation. Aqueous suppressants should be used as necessary. Intractable cases may require a filtration procedure. With the previously described technique, suture erosion and/or lens dislocation is unlikely but may occur.

If these surgical techniques are followed, the majority of the eyes will have the sutures placed in the ciliary sulcus with development of a fibrotic membrane around the haptic. However, up to 23% of the lenses may actually be located posterior to the ciliary sulcus.²⁸ The use of a lens that is too large or too small for the sulcus with a suturing technique that is too tight may induce astigmatism, especially in eyes also undergoing penetrating keratoplasty.²⁹

Good results have also been seen in children without adequate capsular support for an IOL. In one study with follow-up of as much as 38 months, most eyes had a significant improvement in vision after sutured posterior chamber IOLs.³⁰

Conclusion

Implantation of a PCL in cases in which there is no capsular support is a relatively safe and effective technique for visual rehabilitation of the aphakic patient who is spectacle and contact lens intolerant. With appropriate surgical planning and adequate discussion of the potential surgical benefits and risks, secondary PCL implantation frequently provides satisfaction to both the patient and the surgeon.

References

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