21.1 Introduction

In eyes without adequate capsule support during a cataract procedure, the implantation of an iris-fixated iris claw lens is an excellent option.1Other intraocular lens (IOL) fixation options are described in different chapters of this book. Compromised capsular support, or the lack of it, is caused by trauma, complicated cataract surgery, or congenital and secondary weakness of the zonules/capsule. The iris-claw aphakic IOL design is not FDA-approved for routine use in the United States but may be available for compassionate use in select cases.

21.2 Aphakic Iris Claw Lens

The Artisan/Verisyse aphakic IOL (Abbott Medical Optics, Inc.) is a polymethyl methacrylate (PMMA) IOL, with an 8.5-mm length, a 1.04-mm maximum height, and a 5-mm clear optical zone (Fig. 21.1, Fig. 21.2). In 1971, Jan Worst presented the “Iris-Claw Lens” (a biconvex PMMA IOL fixated above the bridal plane at the midperiphery of the iris) at a meeting in Paris. In 1986, a modified biconcave phakic version of the Artisan was first implanted by Fechner for refractive surgery purposes. The aphakic model was redesigned in 1996 (convex/concave). The aphakic design is not FDA-approved for routine use in the United States but may be available for compassionate use in select cases.

21.3 Lens Power Calculation

The most common lens power calculation is A=P+2.5×L+0.9×KA=P+\left(2.5\times L\right)+\left(0.9\times K\right). Where A is the A-constant, 115 (ultrasonic biometry), P the predicted IOL power, L the axial length in millimeters, and K the average keratometry in diopters (if optical biometry, the A-constant is 115.7).

The manufacturer’s recommended A-constant for anterior fixation is 115 (for posterior fixation, we propose a surgeon’s A-constant of 117). The optic power is calculated by using the SRK/T formula. The power range is from + 2 to + 30 diopters (D) (in 1 D increments) and + 14.5 to + 24.5 D (0.5 D increments). The pediatric aphakic Artisan lens has an optic of 4 or 5 mm and an overall diameter of 6.5, 7.5, or 8.5 mm.

21.4 Surgical Technique for Capsule Rupture during or after Phaco Procedure

Before starting the Artisan lens implantation, a meticulous bimanual anterior vitrectomy is mandatory, after or before the irrigation/aspiration (I/A) step of the capsular bag. If necessary, the use of triamcinolone, to visualize the vitreous, is recommended. The pupil must be round and the anterior chamber totally free of vitreous, nucleus, and cortical material. The main phaco-incision is enlarged to 5 mm. The two I/A paracenteses are now used for the enclavation sites. Acetylcholine 1% is injected into the anterior chamber to achieve miosis. To protect the corneal endothelium, the anterior chamber is filled with a cohesive ophthalmic viscosurgical device (OVD). To facilitate the enclavation step, it is sometimes recommended to inject some of the same OVD behind the iris at the same place of the enclavation. The IOL is then inserted into the anterior chamber with the grasping forceps (Fig. 21.3), rotated 90° into a horizontal position (Fig. 21.4) and well centered over the pupil (Video 21.1). The optic of the IOL is held firmly with the grasping forceps and fixated with the enclavation needle, which has a bent shaft and a bent tip that pushes the iris into both claws. The needle is introduced through one of the paracenteses and holds up a fold of iris while the lens is slightly depressed with the implantation forceps so that the claws automatically grasp the iris (Fig. 21.5, Fig. 21.6). Then the hands are switched and the same maneuver is performed through the other paracentesis. Fixation of the iris claws and proper centration of the IOL over the pupil are checked before the next step. A peripheral surgical slit iridotomy using microscissors is performed at 12 o’clock to prevent pupillary block. The corneal wound is then sutured with a 10–0 nylon suture (Fig. 21.7). Proper tension of the sutures is checked. Finally, the OVD is removed with the bimanual I/A system. If necessary (with astigmatism > 1.5 D), the suture(s) are removed 6 weeks postoperatively.

If it is necessary—in the presence of iris defects—an Artisan reconstruction implant (Fig. 21.8) may be used, but only where there is still some remaining iris tissue. This lens in not available in the US. This step of surgery is done in the presence of a vitreous-free anterior chamber and under the OVD. The technique of enclavation is basically the same as for the classic aphakic Artisan lens. ¹ Iris repair with Aritsan implantation can also be performed (Video 21.2).

21.5 Iris Claw Implantation in the Presence of Marfan’s Syndrome

The iris-encalvation technique can also be useful to correct aphakia in patients with Marfan’s syndrome with a 2-step procedure (Fig. 21.9). All patients have a full eye examination that included distance visual acuity measurement using a Snellen or illiterate “E” chart, cycloplegic refraction, keratometry, biometry, slit-lamp evaluation of the anterior segment and the lens subluxation, intraocular pressure measurement, and posterior segment evaluation. Preoperative and postoperative endothelial cell counts were attempted in all cases. No eye had dislocation of the subluxated lens into the anterior chamber or vitreous or a cataractous lens.

Preoperatively, the pupil was dilated. Surgery was performed under general anesthesia. At 12 o’clock, a main corneal incision of 2.2 mm was performed. Two paracenteses were placed at 10 and 2 o’clock. The anterior chamber was filled with a dispersive OVD. An anterior minicapsulorhexis was created and hydrodissection was performed. The lens material was aspirated by the I/A cannula. Once the capsular bag was empty, this complete capsular bag was pulled out through the main incision with a microforceps. Acetylcholine 1% was injected into the anterior chamber to constrict the pupil. If vitreous was seen in the anterior chamber, anterior vitrectomy was performed. Hydration of the wound finished the surgery.

Because calculation of the IOL power is not accurate in the presence of a subluxated lens, it is performed 6 weeks after surgery (Fig. 21.10). At that time an appropriate aphakic Artisan lens is implanted using the same technique as that already described (Videos 21.3 and 21.4).

21.6 Posterior Iris Fixation of the Iris Claw

For posterior iris fixation of the Artisan lens (Fig. 21.11) a main incision of 5 mm and two paracenteses at 2 and 10 o’clock are performed. After an intracameral injection of acetylcholine 1% through the paracentesis, cohesive OVD was injected behind the pupillary plane to tamponade the vitreous and increase the pressure behind the enclavation site and also to facilitate the enclavation step. The Artisan lens was inserted through the main incision upside-down (Fig. 21.3), in a reversed position. The lens was rotated with a hook into a horizontal position from 3 to 9 o’clock (Fig. 21.4) and centered over the pupil. A holding forceps was introduced through the main incision to grasp the IOL and then slip it through the pupil area. The lens was maintained horizontally with the forceps, then reentered over the pupil behind the iris plane with the haptics positioned again at 3 and 9 o’clock. The correct position of the IOL should be checked before iris enclavation. At the same time, through the paracentesis, an enclavation needle was introduced and the haptics were enclavated (Fig. 21.5, Fig. 21.6). Too much pressure on the pupil margin should be avoided by not engaging too much iris tissue in the claw. Displacement, ovalization, and pupil deformation must be avoided. The maneuver then was repeated on the other side, achieving perfect IOL centration under the pupil. Finally, all the OVD was removed, and the wound was closed with nylon 10–0 (Fig. 21.7).