Glued iris prosthesis can be used in eyes with congenital aniridia, subluxated cataract

A surgeon describes a technique that involves lensectomy and implantation of a PMMA aniridia IOL.

Thomas John

The iris diaphragm provides color to the eye’s cosmetic appearance. In addition, it regulates the amount of light that enters the eye in a range of lighting conditions by varying the pupillary size and thus provides a comfortable viewing condition for the subject. Any compromise to this iris diaphragm, such as congenital absence, traumatic loss and destruction, or iatrogenic damage, can result in unwanted glare and suboptimal quality of vision.

Ophthalmic surgeons have described various iris suturing techniques to fix iris deficiencies in a symptomatic patient. For the most part, these techniques improve the patient’s visual quality, but new suturing techniques are needed to facilitate such iris repair. With the introduction of the aniridia IOL, such iris repair may be shifted from the iris plane to the prosthetic plane of the IOL, thus alleviating the need for demanding iris-suturing techniques in patients who require both iris and lens surgery.

In this column, Dr. Agarwal describes a surgical technique of using a glued iris prosthesis, namely a PMMA aniridia IOL. This IOL is not currently approved by the U.S. Food and Drug Administration for use in the U.S.

Thomas John, MD
OSN Surgical Maneuvers Editor

by Amar Agarwal, MS, FRCS, FRCOphth

Amar Agarwal

A glued iris prosthesis (Figure) can be implanted in eyes with congenital aniridia and subluxated cataract and in cases of traumatic total aniridia with aphakia. The glued iris prosthesis we use is a PMMA aniridia IOL, the OV lens style ANI5 from Intra Ocular Care. The optic has a central clear zone (5 mm in diameter) with a peripheral opaque or pigmented annulus (2.25 mm) and an A-constant of 118.2. The overall diameter of the IOL is 12.75 mm. Lensectomy is initially performed in eyes with subluxated cataract followed by glued iris prosthesis.

Surgical technique

Two partial-thickness scleral flaps about 2.5 mm × 2.5 mm are created exactly 180° diagonally apart. An infusion cannula or anterior chamber maintainer is fixed. Superior 2.8 mm entry with a keratome is made, and lensectomy is performed to remove the subluxated cataractous lens with a vitrectomy cutter. Anterior vitrectomy is completed to remove any vitreous traction. Two straight sclerotomies with a 20-gauge needle are made under the existing scleral flaps 1 mm to 1.5 mm from the limbus. The limbal incision is enlarged with a sharp keratome or corneoscleral scissors.

Preoperative image of congenital aniridia with subluxated cataract (a). Postoperative outcome (b). Traumatic aniridia with aphakia (c). Postoperative image (d). Congenital aniridia with subluxated lens (e). Postoperative image of the same patient (f). Image: Agarwal A

The PMMA aniridia implant is introduced through the limbal incision using McPherson forceps. End-gripping 25- or 23-gauge micro-rhexis forceps (MicroSurgical Technology) are passed through one of the sclerotomies to hold the tip of the haptic. The haptics are then externalized under the scleral flap. A scleral tunnel is made with a 26-gauge needle at the point of externalization of the haptic, and the haptic is tucked into the intralamellar scleral tunnel. The scleral flaps are closed with Tisseel fibrin glue (Baxter). The infusion cannula or anterior chamber maintainer is then removed. The procedure can also be performed with a 23-gauge trocar cannula infusion. The limbal wound is closed with 10-0 monofilament nylon sutures. The conjunctiva is also apposed with the fibrin glue.

Glued iris prosthesis

IOL implantation alone without addressing the iris deficiency may potentially result in a worse functional visual quality due to aberrations induced by light at the margin of the IOL. Congenital aniridia is known to be associated with subluxated cataract or zonular weakness, while trauma may lead to iris deficiency, mydriasis or iridodialysis. Therefore, management of both the iris and the lens capsular deficiency with provision of good anatomical, functional and cosmetic results for the patient is vital.

Use of a colored lens diaphragm was reported as early as 1964. Choyce initially designed an anterior chamber lens with an optic surrounded by a colored diaphragm. Later, Reinhard and Sundmacher reported implantation of a single-piece black iris diaphragm IOL for the correction of aniridia. They also showed that implantation of the black diaphragm aniridia IOL improved visual acuity in the majority of patients with a variety of endogenous problems in addition to aniridia. Gabor et al introduced intrascleral sutureless posterior chamber IOL implantation in eyes with deficient capsule. We use scleral flaps to cover the haptics in the scleral tunnel and fibrin glue to create a hermetic seal, unlike the procedure by Gabor et al in which the haptics are introduced directly into the scleral tunnel.

As compared with sutured iris prosthesis, 10-0 or 9-0 Prolene, which is used for trans-scleral fixation of the prosthesis to the sclera, is not used. Instead, scleral tuck and fibrin glue are used for good surgical adhesion. Our earlier reports on the glued IOL method have shown good results with IOL centration. The limitation with aniridia IOL implantation with this method is the need for large incisions, which can lead to postoperative astigmatism. Nevertheless, the technique can be performed with ease with any available aniridia IOL that has rigid haptics. One can combine the glued iris prosthesis along with other surgeries such as penetrating keratoplasty, trabeculectomy or pars plana vitrectomy.

References:

• Banaee T, Sagheb S. Scleral fixation of intraocular lens in eyes with history of open globe injury. J Pediatr Ophthalmol Strabismus. 2011;48(5):292-297.
• Blackmon DM, Lambert SR. Congenital iris coloboma repair using a modified McCannel suture technique. Am J Ophthalmol. 2003;135(5):730-732.
• Cionni RJ, Karatza EC, Osher RH, Shah M. Surgical technique for congenital iris coloboma repair. J Cataract Refract Surg. 2006;32(11):1913-1916.
• Shin DH. Repair of sector iris coloboma. Closed-chamber technique. Arch Ophthalmol. 1982;100(3):460-461.

• Amar Agarwal, MS, FRCS, FRCOphth, can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; email: dragarwal@vsnl.com; website: www.dragarwal.com.
• Edited by Thomas John, MD, clinical associate professor at Loyola University in Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; fax: 708-429-2226; email: tjcornea@gmail.com.
• Disclosures: Drs. Agarwal and John have no relevant financial disclosures.