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January 2013
 

CATARACT
 

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.



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.

Patients 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.



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.



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.



Iridodialysis repair

Iridodialyses can often be repaired by suture techniques. The surgeon should be aware that the pupil will be drawn in the direction of the iridodialysis, especially if too much peripheral iris tissue is incarcerated in the 10-0 nylon suture bites. Iridodialyses are associated with denervation of the iris in the sector of disinsertion. Post-op, these eyes will often have oval mydriatic pupils (Figure 1).



Mydriatic pupil repair

A mydriatic pupil can be repaired by a purse string pupilloplasty technique. Although this approach results in a functionally smaller pupil, it is always nonreactive and often stellate upon close inspection (Figure 2). It is important for the surgeon not to pull the sutures down too tightly. Doing so may result in cheese wiring through the pupil sphincter or a pupil that is too small.
A few clinical examples will serve to illustrate how artificial iris devices can be used to compensate for other small and large iris defects.



Morcher example

Morcher manufactures many different artificial iris devices. Some are modified capsule tension rings. Others are iris reconstruction lenses that contain an integrated optic. All feature a black artificial iris that is manufactured from modified polymethylmethacrylate. An example is shown in Figure 3.



Ophtec example

Ophtec also manufactures several artificial iris devices. The model 311 iris reconstruction lens comes in blue, green, and brown. These devices can be used to replace the natural iris when there is concomitant aphakia. They can also be used in a piggyback fashion to correct an eye that is pseudophakic but has a residual refractive error. Suture fixation eyelets on the haptics allow for suture fixation to the sclera when capsular bag and zonular support are absent. An example is shown in Figure 4.



HumanOptics example

HumanOptics sells a silicone wafer device that is manufactured by Dr. Schmidt Intraocularlinsen GmbH (Saint Augustin, Germany). This device has a 12.8 mm overall diameter and a 3.35 mm pupil. It is a custom, hand-painted device that is usually matched to the fellow normal eye, if there is one. It is rollable and can be inserted through a sub-4 mm incision. The cosmetic results that can be obtained with it are usually superior to those that can be obtained with Morcher and Ophtec devices. An example is shown in Figure 5.



Summary and conclusion

Patients with congenital and acquired defects of the iris are challenging. Sutures can be used to repair iridodialyses, small iris lacerations, colobomatous defects, and mydriatic pupils. Prosthetic iris devices from Morcher, Ophtec, and HumanOptics can be used to correct larger defects. To obtain access to the latter, ophthalmologists in the U.S. have to obtain an FDA compassionate use device exemption or refer their patient to a surgeon who participates in a clinical trial. Caring for these patients is very gratifying. They are usually appreciative of any improvement the ophthalmologist can achieve in reducing the light and glare sensitivity they experience.



References

1. Osher RH, Burk SE. Cataract surgery combined with implantation of an artificial iris. J Cataract Refract Surg. 1999;25:1540-1547.
2. Burk SE, Da Mata AP, Snyder ME, Cionni RJ, Cohen JS, Osher RH. Prosthetic iris implantation for congenital, traumatic, or functional iris deficiencies. J Cataract Refract Surg. 2001;27:1732-1740.
3. Price MO, Price FW Jr., Chang DF, Kelley K, Olson MD, Miller KM. Ophtec iris reconstruction lens United States clinical trial phase I. Ophthalmology. 2004;111:1847-1852.
4. Miller AR, Olson MD, Miller KM. Functional and cosmetic outcomes of combined penetrating keratoplasty and Ophtec iris reconstruction lens implantation in eyes with a history of trauma. J Cataract Refract Surg. 2007;33:808-814.
5. Chung MY, Miller KM, Weissman BA. Morcher iris reconstruction lens and rigid contact lens for traumatic aniridia. Eye Contact Lens. 2009;35:108-110.
6. Aldave AJ, Baghdasaryan E, Miller KM. Descemet stripping endothelial keratoplasty after Ophtec 311 iris reconstruction lens implantation. Cornea. 2011;30:405-408.
Editors' note: Dr. Miller is Kolokotrones Professor of Clinical Ophthalmology, David Geffen School of Medicine, Jules Stein Eye Institute, UCLA. He has no financial interests related to this article.



Contact information

Miller: kmiller@ucla.edu







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