12 Aniridia Intraocular Lenses
Aniridia is defined as the absence of iris tissue in its anatomical location. It can be total or partial. Aniridia can be congenital or acquired. Absence of iris can lead to glare and poor visual quality. Aniridia can be managed by iris implants or aniridia intraocular lens. This chapter gives an overview on the iris reconstruction techniques in aniridia and the advantages.
“Aniridia” is the absence of iris tissue, which can be congenital (▶Fig. 12.1) or traumatic (▶Fig. 12.2). It is often associated with lenticular abnormalities. 1 , 2 , 3 Around 50 to 85% of patients with congenital aniridia 1 have cataract associated with zonular weakness and fragile anterior lens capsule. 2 , 3 Penetrating ocular trauma causing iris defects is frequently associated with traumatic cataract, lens subluxation, or dislocation. 4 Lens abnormalities in such patients warrant surgical management. Addressing the iris defects along with intraocular lens (IOL) implantation is crucial to achieve a better visual and functional outcome in these patients.
12.2 Aniridia Intraocular Lens
The use of colored lens diaphragm has been in vogue for decades. 5 , 6 , 7 , 8 Black iris-diaphragm IOLs (BDIs) were tried as early as 1991 to treat aphakia associated with aniridia. 8 They were used to correct congenital and traumatic aniridia associated with lens abnormalities. Since then, aniridia IOLs have undergone various changes with respect to design, position, and method of fixation. Initial reports were on trans-scleral BDIs that were fixated using 9–0 or 10–0 polypropylene sutures. Further innovations led to the development of aniridia lenses that could be placed in the ciliary sulcus in eyes with adequately supportive capsular remnants. 4 Endocapsular IOL insertion, in eyes with intact capsular bags, has also been possible with specific modifications in the design of the aniridia IOLs. 4 , 7 More recently, a novel technique of trans-scleral glued fixation of aniridia IOLs has also been described. 6 , 7 In this technique, the haptics are tucked into scleral tunnels created under scleral flaps. The flaps are then secured with fibrin glue to provide additional stability.
Aniridia IOL is an intraocular lens implant (▶Fig. 12.3) with a uniquely designed optic and rigid haptics. It is made up of polymethyl methacrylate (PMMA) or polyethyl methacrylate. The overall diameter of the IOL varies from 12.5 to 13.75 mm, based on the design. The optic has a central clear zone and an opaque or tinted periphery. The central clear optic diameter varies from 3 to 5 mm, while the peripheral opaque annulus surrounding the clear optic zone extends up to 9 to 10 mm from the center. The C-shaped haptics have eyelets in their center to facilitate suture fixation. This implant offers optical correction and iris reconstruction in one sitting. The central clear zone serves to correct the refractory error. The peripheral opaque zone acts as an artificial iris diaphragm and reduces the amount of light entering the eye. Besides, it also limits the spherical and chromatic aberrations produced by the margins of the IOL. Thus, the aniridia IOL combats the glare and photophobia that are otherwise potentially incapacitating symptoms in patients with aniridia. Additionally, the aniridia IOL offers cosmetic benefits to these patients (▶Video 12.1).