Patients with aniridia can benefit from a glued iris prosthesis

Amar Agarwal

Aniridia is an ocular condition characterized by total or partial absence of the iris. It can be congenital or acquired.

The exact pathogenesis of aniridia is unknown. It has been reported to be caused by a mutation in the PAX6 gene on chromosome 11. Aniridia may be familial or sporadic. Acquired aniridia is due to trauma or occurs after surgery. Cataracts are known to occur in 50% to 85% of patients with congenital aniridia, usually acquired during the first two decades of life.

Ectopia lentis, corneal defects, strabismus, nystagmus, and foveal or optic nerve hypoplasia are some of the associations with aniridia (Figure 1). Patients with aniridia typically complain of glare and photophobia.

Figure 1. A: Congenital aniridia with subluxated cataractous lens. B: Anterior segment OCT image showing the hypoplastic iris with subluxated cataractous lens. Images: Agarwal A

We have used our glued IOL technique in eyes with an absent or hypoplastic iris to give better cosmetic and functional outcomes.

Glued iris prosthesis

The glued iris prosthesis is a PMMA aniridia IOL implanted by the glued IOL technique. We used the OV lens style ANI5 aniridia implant (Intra Ocular Care Pvt. Ltd.). The overall diameter of the implant is about 12.75 mm. The optic has a central clear zone of about 5 mm (clear optic zone) with a peripheral opaque or pigmented annulus of about 2.25 mm. The haptics are also made of PMMA with acute angulations. There is an eye on each haptic for Prolene suture placement during transscleral fixation. The IOL power is calculated with the SRK/T formula, and the specific power is implanted.

Surgical technique

Two partial thickness scleral flaps about 2.5 mm × 3 mm are created exactly 180º diagonally apart and about 1.5 mm from the limbus. The infusion cannula or anterior chamber maintainer is fixed. A superior 2.8-mm entry with a keratome is made, and a lensectomy is performed to remove the subluxated cataractous lens (Figure 2A) 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. The limbal incision is enlarged with a sharp keratome or corneoscleral scissors.

Figure 2. Glued iris prosthesis A: Lensectomy is performed. B: The PMMA aniridia implant. C: The haptic is externalized under the scleral flaps. D: The IOL is well-centered at the end of surgery.

The PMMA aniridia implant is then 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 (Figures 2B to 2D) to hold the tip of the haptic. The haptics are then externalized under the scleral flap. Precaution is taken during externalization as the angulation of the haptic with the optic in the implant is different from routine in-the bag or scleral-fixated IOLs. 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 then closed with fibrin glue (Tisseel, Baxter). The infusion cannula or anterior chamber maintainer is then removed. The procedure can also be performed with 23-gauge trocar cannula infusion (Figure 3). The limbal wound is closed with 10-0 monofilament nylon sutures. The conjunctiva is also apposed with the fibrin glue.

Postoperative outcome

Two eyes of two patients underwent this procedure. The first case was an 8-year-old child with congenital aniridia with subluxated cataractous lens, and the second case was an adult man with post-traumatic aniridia with aphakia. The first patient underwent lensectomy with primary aniridia IOL implantation (Figure 2), and the second patient underwent vitrectomy with secondary IOL implantation (Figure 3).

Both patients undergoing this procedure showed symptomatic improvement. Optical disturbances, namely glare and photophobia, reduced markedly. The postoperative best corrected visual acuity was 20/80 in the first case and 20/40 in the second case. There was no loss of BCVA in either eye. The IOP was 10 mm Hg in the first case and 8 mm Hg in the second case. No postoperative uveitis or corneal decompensation was noted in either patient. Anterior segment optical coherence tomography examination showed good IOL centration (Figure 4).

Figure 3. A: Clinical image of traumatic aniridia with aphakia. B: Glued iris prosthesis implanted. Note (arrow) the 23-gauge trocar cannula used as infusion.

Figure 4. IOL centration as seen with anterior segment OCT at 270° to 90° axis.

A new treatment for aniridia

An intact iris diaphragm is essential because it decreases spherical and chromatic aberrations arising from the lens. The symptoms of aniridia range from decreased vision to optical disturbances such as glare or photophobia due to excess light. Eyelid surgery, colored contact lens, sutured scleral-fixated prosthesis, foldable artificial iris or corneal tattooing is used to improve the symptoms.

The usual postoperative complications reported with sutured scleral-fixated IOLs, such as hypotony, inflammation or macular edema, are not encountered in our patients at a mean 8 months of follow-up.

This procedure can be performed in traumatized corneas with any grade of scarring, which is not possible with contact lenses. Uveitis-glaucoma-hyphema syndrome, which is noted with sutured scleral fixation or sulcus-fixated prosthesis or artificial iris, is less observed in our technique. Moreover, good postoperative vision and symptomatic improvement are obtained. Aniridia eyes are shown to have more predispositions to glaucoma; nevertheless, our patients showed normal IOP.

One can combine the glued iris prosthesis along with surgeries such as penetrating keratoplasty, trabeculectomy or pars plana vitrectomy.

• Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Prof. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.