IRIS CLAW IOL FIXATION

RATIONALE AND RESULTS

Jose L. Güell, MD, PhD; Paula Verdaguer, MD, PhD; Daniel Elies, MD; Felicidad Manero, MD; Oscar Gris, MD, PhD; and Merce Morral, MD, PhD

Secondary intraocular lens (IOL) implantation is often a challenging surgical procedure, as patients with aphakia usually have a history of eye trauma or complicated intraocular surgery. If capsular support is spared, IOL implantation in the ciliary sulcus represents the preferred surgery. However, sufficient capsular support is often absent.

The aim of this chapter is presenting the results of 2 related and complementary studies about the safety of secondary iris claw IOL implantation in aphakic eyes without capsular support.

Results suggest that the iris claw Artisan lens (Ophtec BV) in aphakic eyes is an effective, predictable, and safe procedure in the long term. Therefore, we consider the iris claw IOL the first choice to treat patients with aphakic eyes.

Nevertheless, close monitoring of the patient with periodic evaluations that include a complete ophthalmologic exam, intraocular pressure (IOP) measurement, and corneal endothelial cell counts is mandatory.

Introduction

The incidence of surgical complications leading to unplanned aphakia after cataract surgery has been reported to be 0.4%, with the presence of intraoperative capsule problems and vitreous loss being the most frequent reason.¹ Postoperative refractive errors in aphakic eyes are usually substantial, leading to high anisometropia that is difficult to correct with spectacles or contact lenses. Therefore, surgical treatment involving secondary implantation of an IOL is often required to achieve complete visual rehabilitation.^1–3 In eyes without capsular support, different types of IOLs may be implanted. Surgeon experience as well as patient factors such as age, anterior segment anatomy, and status of the corneal endothelium must be considered to decide the best surgical option for an individual patient.

For us, iris claw IOL implantation has become the procedure of choice whenever iris support is feasible. Iris claw IOLs were first introduced by Worst et al in the early 1980s.^4,5 The iris claw Artisan IOL for aphakia is a single-piece, nonfoldable, biconvex IOL made of polymethylmethacrylate that has a 5.0-mm optic and an 8.5-mm overall length. Because iris claw IOLs are fixed to the midperiphery of the iris, problems associated with IOL sizing and damage to the anterior chamber angle and the iris root are avoided. Moreover, the unique enclavation system allows centration of the IOL on the pupillary axis, which is especially important in eyes with decentered pupils, a common condition in these patients. Finally, iris claw IOLs do not interfere with physiological iris vascularization or cause pupillary distortion when properly placed.^6,7

Literature Review

Our first paper is a retrospective, nonrandomized, non-comparative, interventional study that includes 128 eyes of 124 consecutive patients that presented with aphakia and no capsular support and underwent Artisan iris claw IOL implantation between 1997 and 2010.⁶

Our second paper is a retrospective, nonrandomized, comparative, interventional study that included 60 eyes of 30 patients who underwent Artisan IOL implantation for aphakia in one eye and phacoemulsification and IOL implantation or no surgery in the fellow eye between 2005 and 2014.7 For study purposes, we divided the patients into 2 groups:

1. Artisan IOL implantation in one eye and no surgery in the fellow eye
   
2. Artisan IOL implantation in one eye and uncomplicated cataract surgery in the fellow eye

All the studies were approved by the Ethics Committee of the Instituto de Microcirugia Ocular and the Universitat Autònoma de Barcelona. All patients were operated on by the same surgeon (JLG).

PREOPERATIVE EXAMINATION AND FOLLOW-UP

All the patients underwent a complete preoperative ophthalmologic examination, which included ultrasound anterior chamber depth measurement using the Compuscan LT (Storz) and central endothelial cell count (cECC; Konan Noncon Robo-CA). The optometrist who examined the patient selected the best captured digital image and performed the endothelial cell analysis by averaging 3 consecutive measurements using the center-to-center method.

Inclusion criteria included anterior chamber depth from endothelium greater than 3.0 mm, cECC greater than 1800 cells per mm², normal IOP (with or without hypotensive medication), absence of retinal disease, and a minimum follow-up of 1 year.

Exclusion criteria were iris abnormalities hampering enclavation, history of recurrent uveitis, pigmentary glaucoma, proliferative diabetic retinopathy, age-related macular degeneration, and penetrating keratoplasty (in the second study only).

Postoperative follow-up visits were held postoperative day 1, month 1, month 6, year 1, and then annually.

The power of the lens was calculated with the IOL Master V.5 (Carl Zeiss Meditec) with an A-constant of 115.0 and with the ultrasound RxP OcuScan (Alcon Laboratories, Inc).

SURGICAL PROCEDURE

Under retro- or peribulbar anesthesia, a 2-plane, 5.2-mm corneal incision was made at 12 o’clock, and 2 vertical paracenteses were directed to the enclavation area at 10 and 2 o’clock. Before Artisan IOL implantation, indirect illumination was used to detect the presence of vitreous in the anterior chamber, and if so, anterior vitrectomy was performed so that vitreous strands did not interfere with Artisan IOL implantation.

Acetylcholine chloride 1% was injected into the anterior chamber to achieve miosis. To protect the corneal endothelium, the anterior chamber was filled with dispersive and cohesive viscoelastic material. The IOL was then inserted, rotated 90 degrees into a horizontal position, and centered over the pupil. Each iris claw was fixed to the midperiphery of the iris with an enclavation needle, and proper centration of the IOL over the pupil was checked. A peripheral surgical iridectomy using scissors was performed at 12 o’clock to prevent pupillary block. The corneal wound was then sutured with 5 interrupted 10-0 nylon sutures. The proper tension of the sutures was checked with a standard qualitative Maloney keratoscope. Finally, the viscoelastic material was removed with a bimanual irrigation/aspiration system. None of the patients had silicone oil in the vitreous cavity at the time of Artisan implantation. Sutures were selectively removed starting 10 weeks postoperatively, depending on the patient’s refractive and topographic astigmatism (Figure 56-1).

RESULTS

In the first study, mean age was 54.55 years (SD 21.48), and mean follow-up was 41.8 months (SD 23.63). Table 56-1 summarizes pre- and postoperative logMAR uncorrected distance visual acuity (UCVA), logMAR best spectacle-corrected visual acuity (BSCVA), spherical equivalent, and cECC before and after the surgery during 5 years.

UCVA and BSCVA initially improved after surgery (Figure 56-2). A slight but statistically significant decrease in cECC was observed (P < .05; Figure 56-3).

Thirty-five (27.34%) patients had preexisting chronic open-angle glaucoma that was adequately controlled with topical medication. Following IOL implantation, no changes in the hypotensive regime were required. No patients without preoperative glaucoma had an increase in IOP after surgery. Main complications were pupillary block due to nonpermeable surgical iridectomy (n = 2, 1.56%), transient increase in IOP (n = 3, 2.34%), IOL replacement (n = 1, 0.78%), penetrating keratoplasty and IOL removal (n = 2, 1.56%), and cystoid macular edema (n = 4, 3.12%).

In the second study, Group 1 included 44 eyes of 22 patients. Group 2 included 16 eyes of 8 patients who underwent iris claw IOL implantation in one eye and phacoemulsification and in-the-bag IOL implantation in the fellow eye. Table 56-2 summarizes baseline characteristics for both groups. No statistically significant differences in preoperative corrected distance acuity were found between the Artisan implanted eyes and the eyes that underwent cataract surgery (P = .47). Preoperative cECC was significantly lower in the eyes that underwent iris claw IOL implantation compared with unoperated eyes (P < .01) but not compared to the eyes that underwent cataract surgery (P = .67).

In Group 1, postoperative uncorrected and corrected distance acuity were significantly worse in the Artisan implanted eyes (P < .01). In Group 2, no significant differences in uncorrected or corrected acuity were found between the Artisan-implanted eyes and the eyes that underwent cataract surgery throughout the follow-up (P ≥ .05). No statistically significant differences were found in postoperative spherical equivalent between the Artisan-implanted eyes and the unoperated eyes or the eyes that underwent cataract surgery (P ≥ .05). Table 56-3 shows acuity and spherical equivalent values at each follow-up point for each group.

Table 56-4 summarizes cECC and percentage of the corneal endothelial cell loss at each follow-up point. In Group 1, cECC was significantly lower in the Artisan-implanted eyes throughout the follow-up (P < .01). In Group 2, cECC was non-significantly lower in the Artisan-implanted eyes postoperatively (P ≥ .05). No significant differences were found between groups (Figure 56-4).

No intraoperative complications were observed in either group. Postoperative complications after Artisan-IOL implantations included transient increase of IOP (n = 4, 13.3%), IOL replacement due to refractive reasons (n = 2, 6.6%), penetrating keratoplasty and IOL removal (n = 2), cystoid macular edema (n = 1, 3.3%), and retinal detachment (n = 1). Five (62.5%) of the eyes that underwent uncomplicated cataract surgery developed posterior capsule opacification, but there were no other significant complications.

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