EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/104833
20 EW CATARACT January 2013 Complicated cataract cases Cataract surgery in the setting of iris defects by Kevin M. Miller, M.D. I t is a bit strange to write an editorial for one's own column. Nevertheless, that is what this is. In my article, I attempted to provide an overview of the management of iris defects at the time of cataract surgery. While iris problems are uncommon in clinical practice, they are out there. Aniridic patients often are quite symptomatic, and they present therapeutic challenges. I have tried to provide a framework for evaluating and managing patients with congenital and acquired defects when they come in for cataract surgery. Kevin Miller, M.D., Complicated cataract cases editor Figure 1. A post-traumatic iridodialysis can be repaired with 10-0 prolene sutures after the cataract has been removed, a lens implanted, and any vitreous in the area of the dialysis managed. Horizontal mattress sutures are passed across the anterior chamber, through the peripheral iris, and out through the sclera into a Hoffman pocket. The post-op pupil is usually oval shaped. P atients with cataract and concomitant iris defects are not seen very often in clinical practice. The average ophthalmologist may encounter only a handful a year. But when they do come in, they often present significant therapeutic challenges. Classification The first step in managing aniridic patients is to classify their iris defect properly. This can be done by both etiology and extent. By etiology, iris defects are divided into congenital and acquired types. In typical practice, acquired aniridia is more common than congenital aniridia. However, there are regional variations in presentation across the U.S. and around the world. Hereditary forms of aniridia include colobomas and congenital aniridia. Iris colobomas may be isolated or associated with colobomas of the ciliary body, choroid, and optic nerve. The latter may limit a patient's visual potential and visual field. Congenital aniridia is often associated with limbal stem cell deficiency, corneal neovascularization, glaucoma, zonular laxity or dehiscence, foveal aplasia, poor visual potential, and nystagmus. Acquired defects can be classified as post-traumatic or post-surgical. By extent, iris defects can also be classified as partial or complete. The approach to surgical management depends in some part on the etiology and extent of the iris defect. Figure 2. A post-traumatic mydriasis can be repaired using a 10-0 prolene purse string pupilloplasty technique. It is important to avoid closing the pupil too tightly. Cheese wiring is an occasional consequence. A stellate pupil configuration is more common than a round pupil. Symptoms The most common symptoms of iris defects are glare and photophobia. In some cases, iris defects also cause multiplopia, reduced visual acuity, and reduced contrast sensitivity. For many patients, the symptoms of aniridia are debilitating. Some are unable to drive or hold a job. Many are conscious of the cosmetic disfigurement of their eye. Comorbidities Iris defects seldom occur in isolation. They are often accompanied by problems of other ocular structures including the cornea, trabecular meshwork, lens, zonular apparatus, retina, and optic nerve. Simultaneous treatment of these ocular comorbidities often needs to be performed at the time of iris repair or reconstruction. Concurrent primary or repeat penetrating keratoplasty, anterior or posterior synechiolysis, glaucoma tube shunt revision, suture fixation of a lens implant, excision of scar tissue, and retinal detachment repair are all common simultaneous procedures. Nonsurgical management The nonsurgical management of aniridia includes tinted glasses, occluder patches, tinted contact lenses, and artificial pupil contact lenses. For many patients, nonsurgical management is unsatisfactory. Many will present for surgical evaluation after years of failed nonsurgical management. Figure 3. Sectoral and coloboma iris defects can be repaired with a Morcher 96F modified capsular tension ring. In the eye shown here, creating a sector iridectomy relieved the corectopia. The iridectomy was managed by implanting a 96F ring inside the capsular bag in front of the IOL. Surgical planning Sutures can often be used to repair small defects of the iris such as iridectomies, iridodialyses, and tonic pupils. Artificial iris implants are required for larger defects. Devices fall into three general categories, which include modified capsule tension rings, iris reconstruction lenses, and rollable silicone wafers. Presently, only three companies sell artificial iris devices worldwide. They are Morcher (Stuttgart, Germany), Ophtec (Groningen, the Netherlands), and HumanOptics (Erlangen, Germany). At the time of this writing, none of these companies has a device that is FDA approved in the U.S., although they are widely available in Europe and elsewhere. Surgical management If an aniridic eye has a clear lens, it should not be sacrificed to correct the iris defect. Patients with clear lenses should be instructed to wear dark glasses or tinted contact lenses. The surgical approach to the eye with a visually significant cataract and iris defect depends on the status of the cornea, the extent of the iris defect, the status of the lens, the status of the capsule, and health of the zonules. Simultaneous corneal transplantation may be necessary if the native cornea or the current graft has failed. The artificial iris device and lens implant may have to be sutured to the sclera if there is insufficient capsule and zonular support. Figure 4. Large iris defects can be managed with one of several iris reconstruction lenses. In this example, the brown Ophtec 311 was implanted in the sulcus at the time of cataract surgery. An anterior synechiolysis was also performed to relieve iris incarceration into the central corneal scar.