techniques are technically more difficult to perform than ACL insertion. The increase in operative time can potentially increase the risk of intraoperative expulsive suprachoroidal hemorrhage, postoperative endophthalmitis, and prolonged recovery time.

PCLs can be attached to the posterior iris surface by either the haptic or the optic.11–18 Potential disadvantages of iris sutured lenses include iris chafe, iritis, CME, pupillary block, pigment dispersion, glaucoma, and limited pupillary mobility. A small series of patients have documented some of these findings.17 Suture fixation of a lens to the posterior iris surface is also technically difficult through a limbal incision,19 in cases such as aniridia, or where there is limited iris tissue, or following trauma or multiple surgical procedures.

TS PCLs have a number of advantages over irissupported lenses. Using a transscleral fixation technique, the lens haptics come to rest in the ciliary sulcus by accurate placement of sutures through the scleral wall overlying the ciliary sulcus. With no suture or lens attachment to iris tissue, there is less iris chafe, pigment dispersion, iritis, and CME. In addition, pupillary motility remains unrestricted with a transscleral fixation technique.

Transsclerally fixated IOLs are equally effective through open sky or limbal approaches, and can be particularly useful if inadvertent capsular rupture is encountered during routine cataract extraction. In addition, transscleral fixation of lenses is the preferred procedure in patients with aniridia, eyes with loss of iris tissue from trauma, multiple peripheral iridectomies or large sector iridectomies, and in patients having extensive PAS formation, shallow anterior chambers, or glaucoma.

ANATOMIC CONSIDERATIONS

PATIENT SELECTION AND

PREOPERATIVE EVALUATION

It is critical that careful preoperative evaluation and surgical planning be performed prior to initiation of transscleral suture fixation techniques.22 Primary TS PC IOL implantation candidates are those patients undergoing routine cataract surgery whose surgery is complicated by unexpected posterior capsular rupture, vitreous loss, and vitrectomy. At the conclusion of vitrectomy these patients are found to have inadequate residual anterior capsular support for sulcus fixation of a standard PC IOL. These cases are discussed below.

Suitable candidates for secondary IOL implants are aphakic patients who are either spectacle or contact lens intolerant. Pseudophakic patients with chronic CME, secondary glaucoma due to PAS, or corneal endothelial embarrassment with endothelial cell loss are also good candidates for secondary IOL with removal of the offending IOL.

All patients should undergo a complete ocular examination prior to surgery. Retinal abnormalities should be ruled out with careful ophthalmoscopy. If there is clinical suspicion of a macular abnormality, fluorescein angiography should be performed.

IOL calculations computed with accepted formulas using keratometry readings and axial length as measured by A-scan ultrasonography need to be performed even if the aphakic contact lens or spectacles refraction is known. Gonioscopy and endothelial cell counts are crucial to surgical planning.

SURGICAL PLANNING AND CHOICE OF

INTRAOCULAR LENS

In designing a lens and surgical technique for implantation and transscleral fixation, a number of anatomic factors must be considered. The diameter of the ciliary sulcus and its relation to external landmarks are critical anatomic considerations. The ciliary sulcus measures 11.17 mm horizontally and 10.83 mm vertically, and corresponding corneal diameters are 11.67 mm and 10.97 mm.20 Needles passed through the ciliary sulcus and perpendicular to the scleral surface exit 0.46 mm horizontally and 0.83 mm vertically from the posterior limbus.21 As clinical experience has shown, complications of TS PCL fixation are due to inappropriate IOL design and insertion technique. Based on a better understanding of ocular anatomic features, IOL and technique modifications have been recommended to address the observed complications and to improve the safety and effectiveness of TS PCLs.

Careful surgical planning cannot be overemphasized.23 Three areas require careful consideration: astigmatism, endothelial cell assessment, and position and type of IOL implant. Preoperative keratometry should act as a guide to the incision location in the presence of significant astigmatism. In general, the incision should be placed in the steeper meridian of the preoperative cylinder. For example, if two diopters of “with-the-rule” astigmatism exist preoperatively, the surgeon should place the incision over the 90-degree meridian. Postoperative wound slip is a well-known phenomenon occurring 6 weeks to 4 months following surgery when the incision is larger than 7 mm in cord length. By centering the incision over the steep meridian, wound slip with a compensatory decrease in cylinder will occur in that meridian. Occasionally this means that the incision is centered over the temporal area, necessitating a tem-

poral approach or an approach at an oblique axis. The improvement in overall corneal sphericity, however, outweighs the inconvenience of operating in a meridian that is not centered superiorly.

Endothelial cell counts of less than 700 cells per mm3 may preclude secondary IOL implantation. Regional endothelial cell counts may be useful in minimizing surgical trauma. The area with the lowest cell count should be avoided in making the incision, especially if central endothelial cell counts are borderline. In cases of decompensating corneas with low cell counts, consideration should be given to performing penetrating keratoplasty with secondary IOL implantation or exchange.

Gonioscopy should be performed in each patient to determine the location of synechiae, iridotomies, IOL haptics, and vitreous. The presence of PAS may greatly influence the ultimate type and position of the IOL used. The haptics of ACLs should be placed in the angle in a location clear of synechia. Additionally, any iridectomy sites should be avoided. The presence of a patent peripheral iridectomy should be ascertained preoperatively. When patency is in doubt, an additional iridectomy should be performed. The presence and location of vitreous in the anterior chamber must be noted, as this will affect the extent of the vitrectomy to be performed during the procedure. The pupil is then dilated and the amount of peripheral capsule support determined.

The choice of style of IOL implant is largely a question of the surgeon’s personal preference and the degree of capsular support. IOLs should (1) be stable in position over the long term, (2) minimize contact with the anterior chamber angle, and (3) have sufficient iris-to-implant clearance so that iris chafing will not occur. If anterior chamber IOLs are to be used, flexible open-loop IOLs with four-point fixation haptics are preferred. The sizing of these lenses is critical to minimize corneal endothelial cell trauma as well as angle complications. When adequate capsular support is present, a single-piece allpolymethylmethacrylate (PMMA) lens or multipiece PCL can be inserted into the ciliary sulcus utilizing existing peripheral or central capsular support. When the entire capsule is intact, viscoelastic materials and blunt dissection can occasionally be used to “open” the capsular bag, and following polishing of the posterior capsule the lens can be inserted into the lens capsule. If no capsular support is present and a PCL is preferred, a transscleral fixation technique can be employed or a PCL fixated to the iris. Sizing again becomes a critical issue when placing the PCL into the ciliary sulcus. One-piece lenses greater than 12.5 mm in overall diameter are too large to fit into the ciliary sulcus and will often override the sulcus onto the pars plicata with the haptics resting upon

the ciliary processes and even out onto the ora serrata. One-piece all-PMMA PC IOLs with eyelets on their haptics are particularly well suited for transscleral fixation, and techniques for their use are discussed below.

Careful presurgical planning is crucial to the success of any secondary IOL procedure. In this way endothelial trauma may be minimized, excessive astigmatism avoided, and stable fixation of the IOL achieved.

SURGICAL TECHNIQUE OF

SECONDARY TRANSSCLERAL

FIXATED INTRAOCULAR LENSES

Many techniques have been described for transscleral fixation of PCLs.22,23 The following technique is the one the authors find both easiest and most consistent. The pupil is dilated with cyclopentolate hydrochloride 1.0% and phenylephrine hydrochloride 2.5%. A Flieringa ring may be used to lend support to the globe, especially if a vitrectomy is anticipated. Two conjunctival peritomies are made 180 degrees apart in the axis of the steep meridian with Wescott scissors. Wetfield cautery is used to attain hemostasis of the surgical beds. A 7- to 8-mm scleral, grooved, two-plane incision is made in the meridian of the positive corneal cylinder. A paracentesis is made with a 22-degree knife three clock hours away from the initial scleral incision, and the anterior chamber is entered through the scleral incision with a keratome. An automated core vitrectomy is performed if necessary, and the eye is filled with viscoelastic. Alternatively, a pars plana vitrectomy can be performed using an anterior chamber maintainer through the limbal paracentesis.

A one-piece PMMA PCL is selected with an optic size of 6.5 mm or greater, an overall length of 12.0 to 12.5 mm, a biconvex optic, and positioning eyelets on the haptics to assure stable suture fixation and symmetrical lens placement (e.g., Alcon CZ70BD, Storz P66UV).

PREPARING THE DISTAL HAPTIC

One of the long needles of a double-armed 10-0 polypropylene suture (e.g., Ethicon CTC-6L, Ethicon STC-6, or Alcon PC-7) is passed through the eyelet on the inferior haptic of the PCL (Fig. 22–1). The superior wound is opened to its full extent, and the needle is then passed through this wound, over the superior iris, through the pupil, under the inferior iris, through the ciliary sulcus, and out through the sclera, exiting 0.75 mm from the limbus where the in-

ferior conjunctiva had previously been recessed. The other needle is passed in a similar fashion 1.5 to 2.0 mm adjacent to the previous needle’s exit site.

PREPARING THE PROXIMAL HAPTIC

A basal peripheral iridectomy (PI) is made, centered under the surgical wound. The unarmed end of a conventional single-armed 10-0 polypropylene suture (e.g., Ethicon TG140–8) is placed through the wound and peripheral iridectomy under the iris, and passed into the pupillary space under viscoelastic protection. This free end of the suture is then retrieved in the pupillary space and brought out anterior to the iris and through the superior wound (Fig. 22–2). The armed end (needle end) of the suture is left outside the eye for this maneuver.

INSERTION OF THE IOL

The lens is then placed into the eye under viscoelastic protection, with the distal haptic beneath the inferior iris. The inferior polypropylene suture ends are partially pulled up through their exit sites distally. The retrieved free end of the proximal suture is tied onto the inside of the eyelet, which has been left exposed through the superior wound (Fig. 22–3A). This avoids contact of the suture knot to the ciliary sulcus. The proximal haptic, with this suture securely tied to the eyelet, is now placed beneath the iris, using a proximal haptic compression technique (Fig. 22–3B). The eyelet of the proximal haptic with the suture tied to it now lies directly under the basal PI. The needle end of the proximal Prolene suture is

FIGURE 22–1 In placing a transsclerally sutured posterior chamber lens (TS PCL), one of the long needles of a double-armed 10-0 polypropylene suture is passed through the eyelet on the distal haptic of the PCL. The needle is then passed through the wound, over the proximal iris, inside the eye through the pupil, under the distal iris, through the ciliary sulcus, and out through the sclera, exiting 0.75 mm from the limbus. The second needle is passed in similar manner.

next placed through the wound and peripheral iridectomy and driven posteriorly through the posterior scleral incision lip as the anterior wound is reflected back. The suture is pulled up and another partial-thickness suture bite is taken through this posterior scleral lip bed (Fig. 22–4A). The suture is tied to itself and cut short on the knot to fixate the superior haptic (Fig. 22–4B). The knot, within the bed of the corneal scleral pocket, will effectively be buried as the wound is closed.

The distal sutures are pulled up tight and tied together. The suture is cut close to the knot and rotated so the knot is buried (Fig. 22–5). The conjunctiva is reapproximated at the limbus with cautery or suture. Fixation in this way eliminates erosion of the Prolene knots and barbs through the conjunctiva because the suture is buried within the sclera (Fig. 22–6).

The anterior chamber is inspected for the presence of vitreous, and the superior wound is closed with interrupted 10-0 nylon sutures. The conjunctiva is brought down and held in place with suture or cautery. The lid speculum is removed and an eye pad and Fox shield are taped into place over the eye.

Alternatively, but similarly, a double-armed long needled polypropylene suture (Ethicon CTC-6L, Alcon PC-7, etc.) can be used for each haptic eyelet as described for the distal haptic in the discussion above. In this case the lens will be placed obliquely to the wound because suture placement is most easily accomplished utilizing the ends of the wound to accurately drive the suture needles. For example, with the wound at the 12 o’clock position the needles will be driven through the sclera at approximately the 2 and 8 o’clock positions. The lens when placed into the eye will then assume this oblique position.

A

B

The sutures at each position can then be pulled up, tied together, cut short to the knot, and then rotated into the sclera. This effectively buries the knot and avoids future knot erosion.

Dr. Takeshi Sugiura has proposed an interesting new device. In a video presentation at the April 1998 meeting of ASCRS he demonstrated an intraocular pad through which the suture needle was placed before introduction into the eye. The pad and needle assembly was then placed behind and proximate to the iris at the ciliary sulcus. Using the pad as a guide, the needle was then advanced through the ciliary sulcus and out of the eye. The pad ensured proper placement and angulation of the intraocular sutures. It is hoped that this adjunct will be available commercially in the near future.24

FIGURE 22–2 (A) The unarmed end of a single-armed 10-0 polypropylene suture is placed through the peripheral iridectomy, under the iris, and into the pupillary space. It is then grasped within the pupil with a forceps. (B) This end is then brought out through the scleral wound anterior to the iris.

IOL EXCHANGE

Explantation of an ACL during IOL exchange is usually performed because the ACL is associated with corneal endothelial decompensation or chronic UGH syndrome resistant to medical therapy. The closedloop ACLs, notably those with thin haptics, may become enveloped with PAS in the angle. When synechiae are present, explantation techniques involve severing the haptics from the optic and removing the IOL in pieces to avoid bleeding, iridodialysis, or angle damage. The optic must be removed carefully because the severed haptics are sharp and may damage intraocular structures. It is helpful to fill the anterior chamber with viscoelastic material. A spatula may be placed under the optic to serve as a ramp

to prevent capturing the posterior scleral lip during removal. Once the optic has been explanted, the remaining haptics are threaded out through their synechial tunnels until they are free in the anterior chamber and can be easily removed. Directly pulling on the haptics must be avoided, as significant angle bleeding and iridodialysis may result.

Occasionally, it may become necessary to remove a PCL secondary to iris capture, iris chafe, sunset syndrome, or incorrect power. Techniques of removal differ depending on whether the lens optics and haptics are in the ciliary sulcus or capsular bag. The first step is to free the IOL from any attachment to the bag, zonules, vitreous, or posterior iris. During this stage, it is important to preserve as much capsule as possible. On occasion, vitrectomy may be

FIGURE 22–6 Clinical photograph demonstrating the 10-0 Prolene suture beneath the conjunctiva. There is no evidence of any erosion of the polypropylene knot 2 years following TS PCL implantation.

FIGURE 22–5 In completing the TS PCL procedure, the distal knot is rotated so the knot is buried under the sclera. The proximal knot is buried when the scleral flap wound is reapposed with 10-0 nylon sutures.

necessary preceding or following extraction of the implant. Viscoelastic is helpful in maintaining surgical space and can also be used to “viscodissect” open a fibrosed capsular bag. If the haptics are within the capsular bag and cannot be freed without sacrificing capsule support, it may be best to sever the haptics as far peripherally as possible, leaving the residual haptic(s) behind while removing the optic and remaining attached haptic portion.

The IOL is then prolapsed into the anterior chamber, where one of the haptics or optic can be grasped with a forceps and gently pulled through the surgical wound. The remaining optic and haptic are then rotated out through the wound, using a spatula as a ramp to avoid capture of the posterior lip of the wound. If the lens is a three-piece foldable IOL, and the surgeon desires to remove it through a wound measuring 3 to 4 mm, a few options are possible. First, the lens may be folded in the anterior chamber and removed through the wound in a folded configuration. This maneuver is possible with acrylic lenses but ill advised with silicone lenses due to their slippery handling characteristics. Second, the lens optic may be cut completely in half and the two pieces removed separately. The Chu Foldable Lens Cutter (Rhein) or Utrata Foldable Lens Cutter and Retriever set (Rhein) are ideal for this. Finally, if the IOL is a three-piece silicone design, the optic may be cut three quarters of the way across its diameter (perpendicular to the insertion of the haptics), while holding it in position by grasping the proximal haptic. Then, by holding one haptic and removing the lens over a spatula “ramp,” the surgeon may remove the lens in one piece as the lens extends longitudinally. Once the lens is successfully removed, the surgeon may choose to place a new PC or AC IOL as described above.