THE ARTISAN IRIS CLAW LENS FOR ANTERIOR IRIS FIXATION

Kenneth J. Rosenthal, MD, FACS and Nandini Venkateswaran, MD

Why the Artisan Aphakia Lens?

Conventional, anterior chamber angle-supported intraocular lenses (ACIOLs) are the only IOLs that are currently approved by the US Food and Drug Administration (FDA) for use in the absence of adequate capsular support. However, surgeons faced with this situation can implement a variety of techniques for IOL fixation, as described throughout this book. Although these are all highly effective strategies, each has limitations. The lenses are being used off-label, and the techniques can be technically challenging and are sometimes associated with lens IOL decentration, secondary glaucoma, cystoid macular edema, and corneal decompensation.^1–9

The Artisan Aphakia IOL (Ophtec BV)—originally named the Worst claw lens—was developed to address some of the limitations and problems associated with currently available ACIOLs (Figure 57-1). Although standard ACIOLs can be useful in patients who lack sufficient capsular support, their potential shortcomings include decentration and dislocation, iris chafing, pupillary capture, corneal endothelial cell damage, chronic inflammation, and glaucoma. The unique design of the Artisan Aphakia IOL allows ease of insertion, exchangeability, and lack of contact with the anterior chamber angle and cornea. These characteristics render it an excellent surgical option for the management of aphakia in the absence of adequate capsular support.

The Worst Claw Lens

Jan Worst of the Netherlands first presented his invention at a small ophthalmic meeting in Paris in 1970 (personal communication, Jan Worst, MD). As is often the case with novel concepts, the IOL was met with widespread skepticism. Despite this inauspicious beginning, this lens design has been in continuous use worldwide for longer than any other currently available IOL; this leads us to refer to it as the “world’s oldest living lens.”

Worst published his initial experience with this design in 1972.^10,11 In 1976, he received the Binkhorst Medal Award by the American Intraocular Implant Society (now American Society of Cataract and Refractive Surgery) in recognition of his work with anterior iris-fixated IOLs. He filed a US patent in 1978, and during this time deployed this lens for use in Asia for the primary treatment of cataract. The lens was later renamed the Artisan lens by his IOL manufacturing company, Ophtec BV. It is not approved in the United States, although an FDA-monitored clinical trial in adults and children is underway. A phakic, refractive version of this lens is FDA approved for use in the primary treatment of myopia, particularly in patients who are not suitable candidates for corneal refractive surgery.¹²

The current model of the Artisan Aphakia IOL is an 8.5-mm wide single-piece, biconvex, polymethylmethacrylate (PMMA) IOL with a 5.0-mm optic and crab claw–like “pincers” on both sides of the optic. These clips contain fine fissures that permit enclavation (intentional entrapment) of a fold of midperipheral iris stroma on either side of the lens to secure fixation and centration. It is currently available internationally in powers ranging from +14.5 to +24.5 diopters (D) in 0.5 D increments and +2.0 D to +14.0 D and +25.0 D to +30.0 D in 1 D increments. The Artisan Aphakia IOL is attached to the midperipheral iris, an area that has little movement. As a result, there is minimal inhibition to dilation or construction of the pupil. Its only contact with the iris is at its fixation point, which is intended to prevent iris chafing and further pigment dispersion. Its vaulted design also provides space between the IOL optic and iris to reduce the risk of pupillary block. A number of studies have demonstrated that implantation of the Artisan Aphakia IOL results in equal or better outcomes compared with ACIOLs or sutured posterior chamber IOLs (PCIOLs) and with abbreviated surgical times.1–9

ADULTS

The Artisan Aphakia IOL can be implanted primarily in patients post cataract surgery in the setting of preexisting inadequate capsular support. It also serves as a good back-up IOL in lieu of a conventional ACIOL or sulcus PCIOL when there is inadequate intraoperative sulcus support, in traumatic lens subluxation, or if IOL exchange is required. Although the authors prefer a capsule-sparing technique when feasible, the lens can also be used to treat patients with ectopia lentis (eg, Marfan syndrome).^5,13 In patients with corneal disease, the Artisan Aphakia IOL is a suitable option because of the ease of subsequent exchange with refractive power changes after keratoplasty.^14,15

PEDIATRICS

Worst originally designed the Artisan Aphakia IOL for use in pediatric patients (personal communication, Jan Worst, MD). His concept was to implant the IOL in a young child and then exchange it when the refractive error changed with the patient’s growth more easily than a sulcus or in-the-bag IOL. Additionally, because the posterior capsules in children opacify aggressively and capsulotomy may require an additional surgical intervention, it can be used in primary pediatric cataract surgery in conjunction with complete lensectomy and vitrectomy (including removal of the capsular bag).

Wilson recently reported that his results with the Artisan Aphakia IOL were comparable to those with currently available PCIOLs and with previous pediatric experience with the Artisan Aphakia IOL.^16–20

ARTISAN IOL VARIANTS

Although rarely used and not FDA approved, an artificial iris-IOL combination based on the Worst claw concept can be used for iris reconstruction in conjunction with aphakia correction (Figure 57-2).

Surgical Technique

Preoperatively, the pupil is constricted using pilocarpine 2% unless vitrectomy will also be performed (Figure 57-3). Under retro- or peribulbar anesthesia, the conjunctiva is retracted, and a 5.5- to 6.0-mm grooved partial-thickness corneoscleral incision is made. Although the incision is often made superiorly, many patients undergoing Artisan Aphakia IOL implantation have significant surgically induced astigmatism from previous extracapsular cataract extraction or insertion of a rigid PMMA ACIOL. In these cases, the incision may be used to advantage by making it at the topographic flat axis with the sutures tightened to reduce astigmatism. Pars plana trocars are preplaced in anticipation of vitrectomy when indicated. Two side-port incisions are created 45 degrees on either side of the superior limbus to allow access for the enclavation needle (see Figure 57-3A). These incisions should be made obliquely (not radially) so that they are pointing directly toward the proposed location of the claws. If there is a dislocated IOL present, it should be brought into the anterior chamber with vitrectomy if indicated. The incision is then carried to full thickness, and the old IOL is explanted. Triamcinolone acetonide is used to stain any prolapsing vitreous, and additional vitrectomy is performed. Intraocular carbachol or acetylcholine chloride is then instilled to constrict the pupil. The anterior chamber is inflated with a viscoelastic. The globe may be pressurized if needed by placement of irrigation though the pars plana trocars. The Artisan Aphakia IOL is then placed in the anterior chamber, oriented in the horizontal position, and centered (see Figures 57-3B and C). Specially designed curved forceps are used to fixate the lens and provide countertraction during enclavation. The peripheral iris tissue superior to the claw is then swept up into the claw using an angled enclavation needle or forceps (see Figures 57-3D and E). It is often necessary to repeat the maneuver to obtain satisfactory enclavation until a substantial tuft of iris is entrapped in the claw. The main incision is sutured and the trocars removed. Although the lens has an anterior vault, a peripheral iridotomy is usually created preoperatively with a YAG laser or intraoperatively with the vitreous cutter or with Vannas or butterfly scissors (Figure 57-3F).

The Artisan Aphakia IOL can also be fixated in the retropupillary space. This technique is now the most frequently performed method for implantation in much of the world. This was first reported by Amar in 1982.21 Rijneveld et al helped popularize this method in 1994 when they combined retropupillary fixation with open sky penetrating keratoplasy.²²

Hara et al²³ have presented data suggesting that this technique may be superior to transscleral suturing of 3-piece IOLs in terms of surgical trauma, visual rehabilitation, and surgical time. Touriño Peralba et al and others confirmed this finding.^24–29 Retropupillary fixation also makes implantation in eyes with shallow anterior chambers possible (Figure 57-4).

TECHNIQUE

In this technique, the lens is placed through an undilated pupil and held behind the iris by specifically designed forceps. Enclavation is achieved by pressing the iris posterior into the IOL fixation claw. This method of placement has several advantages: (1) it can be used in cases of shallow anterior chambers; (2) it is more easily performed than anterior chamber enclavation because the iris is pushed back into the claw, which forms a firm backboard against which enclavation is achieved; and (3) it is somewhat more aesthetically pleasing, because only the retropupillary part of the IOL is visible, with fewer IOL reflections. Disadvantages of this technique include the risk that if dislocation (de-enclavation) occurs, the IOL will dislocate into the posterior segment, requiring vitrectomy, although this is a rare complication.

COMBINATION WITH OTHER SURGICAL PROCEDURES

The Artisan Aphakia IOL is often implanted in eyes in conjunction with IOL exchange or vitrectomy, including retinal detachment repair.^30–34 It can also be used as a “rescue lens” to replace a malpositioned IOL, even in the presence of IOL-induced corneal endothelial cell loss. It can also be used in conjunction with penetrating keratoplasty or lamellar corneal surgery.^35–37 The Artisan Aphakia IOL may have some advantages over conventional in-the-bag IOLs because patients undergoing corneal surgery frequently experience refractive shifts; the Artisan Aphakia IOL may be implanted and later exchanged more easily than conventional IOLs.

Partial or complete iris defects are frequently seen in association with trauma, whether surgical or not, or from chronic inflammation. These can be addressed by suture closure or with implantation of an artificial iris, along with Artisan Aphakia IOL implantation if the repaired iris can support the iris claws.³⁸

COMPLICATIONS

Although generally very well tolerated, the Artisan Aphakia IOL may be associated with problems.

De-Enclavation

Disengagement of the iris claw and subsequent lens dislocation or lens decentration may occur. Risk factors include ocular trauma or enclavation of an inadequate amount of iris tissue at the time of surgery. There also may be an association with placement of the IOL in the vertical orientation, possibly from the effect of gravity. Vertical placement of the lens should be discouraged except when horizontal orientation is not possible, such as inadequate or absent iris tissue at 3 and 9 o’clock (Figure 57-5).^32,33

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