Article

Iris defect treatment update

Options include a recently FDA-approved prosthesis.

Iris defects present both varied symptoms and uniquely personalized treatment options depending on the type, etiology, size and associated comorbidities. Although at times the defects may present seemingly insurmountable clinical and surgical challenges, advances in treatments have allowed for satisfying outcomes. One of the latest treatment options is the recently FDA-approved CustomFlex Artificial Iris (HumanOptics AG). Currently, this silicone, customizable device is the only FDA-approved iris prosthesis.1,2

Read on for a review of our options for treating iris defects.

BEGIN WITH THE INDIVIDUAL

For starters, approach each patient individually. A careful history and exam will disclose subtleties that may be crucial to the treatment plan. While some defects are seemingly obvious, other more subtle abnormalities may be the cause of a patient’s symptoms. For instance, one or more seemingly small defects may cause monocular diplopia or multiplopia. Other defects may allow ambient light to strike the optic or haptic edge, inducing debilitating glare or photophobia.

Interestingly, some patients with small defects may have greater symptoms than others with larger defects, depending on other factors, including their relative amount of choroidal pigment. Comorbid corneal, glaucomatous or retinal diseases are frequent in this population and must be carefully considered as part of the overall treatment plan.

An underappreciated aspect of how patients are impaired by iris defects is the psychosocial impact that these iris defects may cause. An altered body image and undesirable cosmesis of the defect can lead to clinical depression and anxiety.3

NONPROSTHETIC IRIS DEFECT MANAGEMENT

The traditional therapies for iris deficiencies vary in their efficacy. So-called “aniridic contacts” utilize an opaque periphery within the contact lens to limit incoming light, but these rest more anteriorly than the native iris, at the corneal plane. Therefore, some patients, particularly pseudophakes, still experience debilitating glare since light entering the contact lens aperture can enter the eye obliquely and thereby still hit the optic margin. Also, because the contact lens sits much more anteriorly to the nodal point of the eye than the iris plane, patients can experience a noticeable visual field constriction. Additionally, patients with corneal comorbidities do not typically tolerate contact lenses as well.

Corneal tattooing suffers the same optical detractions of opaque periphery contacts lenses and is not reversible. Alio et al. studied 234 eyes with tattooed corneas, of which 49% had residual light sensitivity.4 MRI imaging artifacts and visual field artifacts have also been reported following corneal tattoo.4,5

Also, while a variety of iris suture repair techniques are available, they are limited by the extent and quality of residual iris tissue. Further, the execution of some of these techniques requires rarified skill sets.

ARTIFICIAL IRIS TYPES

A variety of iris prosthetic devices are manufactured worldwide. While only the custom, flexible iris device is available in the United States, it is important to have an understanding of the global marketplace.

First, avoid confusing the reputable therapeutic devices described in this article with the BrightOcular anterior chamber iris implants placed for cosmetic iris color change, as numerous cases of sight-threatening complications have been reported.

Here are the available devices:

  • Combined iris prosthesis-IOL. Ophtec BV, Morcher and Reper manufacture products within this category. The PMMA models can be quite large, with outer diameters from 7 mm to 10 mm and overall lengths of 12.5 mm to 13.75 mm. However, for sectoral loss, some models come in partial designs that require a smaller entry wound. The colors available are a bit unnatural in many cases, from black (Morcher) to light blue, light green or medium brown (Ophtec). Reper is a newer Russian firm. Its acrylic products come in a variety of colors. Surgeons may find placing the larger, rigid combined iris-IOL devices in the capsular bag challenging because of bulk. Sometimes these devices can be placed in the ciliary sulcus, either passively or with scleral fixation, depending on patient anatomy.6-9 The central apertures vary depending on model type selected. These devices are not available in the United States.
  • Rigid endocapsular iris prostheses. The black PMMA capsular tension ring (CTR)-based devices can be placed through a smaller incision than the combined iris-lens models, and all require implantation in an intact capsular bag (except the Morcher 96C model, which can be implanted into the sulcus). The fin designs can be used to treat complete or partial iris defects, but they can be difficult to align and the optic is inserted separately. Therefore, if the fins misalign or if the optic does not overlap well, then the result could be severe dysphotopsias.10 The modular design from Ophtec allows a smaller incision for insertion into the eye through a clear corneal self-sealing incision; however, this prosthesis requires significant surgical manipulation and dexterity to lock the fixing and locking element in place once the multiple pieces are placed in the capsular bag.11 These devices are similarly not available in the United States.
  • Foldable iris prostheses. HumanOptics’ artificial iris has been implanted in Europe for more than 15 years and only by compassionate use in the United States for the past 11 years. For the past 6 years, it was studied in the FDA trial and received FDA approval in 2018. The silicone design with a fiber and fiber-free option requires only 3.2-mm and 2.5- to 2.8-mm incisions, respectively. In patients with unilateral defects, a hard-copy photo of the fellow eye is sent to customize the color of the prosthesis. In patients with congenital bilateral defects, a hard copy of a desired iris color is then sent for customization. The artificial iris has a 12.8-mm diameter and 3.35-mm pseudopupillary aperture with a tapered peripheral profile down to 0.25 mm to prevent synechiae. The anterior surface has an undulated design to prevent reflection of light, and at a casual-conversation distance it usually looks identical to the fellow eye (Figure 1). The fiber option is designed for use with sutures, while the fiber-free option is used for insertion directly into the capsular bag with a capsular tension ring.12-16 Given the custom-made nature of the device, cost may limit accessibility in some patient settings.

Figure 1. Custom, flexible iris prosthesis slit lamp (right) and mid-face (left) images, preop (top) and postop (bottom).

Reper makes a foldable hydrophobic acrylic device that comes in several designs either with or without an optic and/or fixation elements along its periphery. It can be inserted into the capsular bag or in the ciliary sulcus.9 (The Reper unit is available in select countries outside the United States).

IMPLANTATION OPTIONS

One of the first steps in implanting HumanOptics’ CustomFlex Artificial Iris (besides getting an excellent-quality hard-copy photo of the unaffected eye) is to obtain accurate measurements for sizing. This is done by directly measuring the sulcus, ultrasound biomicroscopy, wide-angle anterior segment OCT or white-to-white measurement. The iris can then be trephined to the correct size.

Here is a brief overview of the implantation options:

  • Capsular bag implantation. This is performed in the setting of an intact capsular bag (Figures 2 and 3). First, the IOL and CTR are placed, then the capsular bag is measured directly and an injector is used to place the iris prosthesis in the capsular bag. A device can be placed secondarily into the bag if the capsule and capsulorhexis remain intact, and the bag can be fully reopened with viscodissection. While either the fiber-embedded or fiber-free devices can be placed in the bag, the fiber-free device is softer and more easily manipulated into position.

    Figure 2. In-the-bag custom, flexible iris, post-iridocyclectomy.

    Figure 3. Retroillumination image of custom, flexible iris and Cionni ring in the bag.

  • Scleral fixation of prosthesis and lens separately in aphakia. Scleral fixation is required in patients without capsular support. A 7-mm incision should be used for insertion of the PMMA lens. Then, the device and IOL are sequentially sutured to the scleral wall, either through the same sclerotomes or separate sclerotomies based on surgeon preference. The version with embedded polyester mesh can increase tensile strength for suture fixation, though concerns about cheese wiring of sutures may be unwarranted, as cheese wiring has not occurred even with the fiber-free version.
  • Scleral fixation of an iris prosthesis/IOL complex in aphakia. This method allows for insertion of the artificial iris and IOL at the same time. Surgeons have multiple methods of fixating the lens to the iris that can require a 7.5-mm to 9-mm incision, depending on the method. Some surgeons prefer placing only one set of fixation sutures to the eye wall, but the additional steps of fixating the iris device to the IOL ex vivo are required.
  • Open sky during penetrating keratoplasty. Some surgeons prefer to place a scleral-fixated device through the open sky during a penetrating keratoplasty. Others place the iris device and IOL through a scleral tunnel first, then perform the PK as a second step during the same surgical visit.
  • Passive sulcus implantation in pseudophakes. This is a viable and relatively facile option in eyes that have an intact capsular and zonular apparatus and have enough peripheral iris to prevent the device from migrating anteriorly. According to unpublished proprietary data of the manufacturer, there are some reports of device micromovements causing uveitis-glaucoma-hyphema syndrome. In those cases, secondary fixation of the device with sutures is required.

In our experience, patient satisfaction with visual recoveries, reduction in light-related symptoms and improvement in physical self-image are quite high with the custom, flexible iris. Many patients report the experience as “life changing.”

SUMMARY

Although management of iris defects can be quite challenging, new advances mean the outcomes can be very rewarding. With the introduction of the CustomFlex Artificial Iris, we now have a device that accomplishes these goals when traditional iris repair options are not viable. OM

REFERENCES

  1. HumanOptics AG. CustomFlex artificial iris professional use information. https://www.accessdata.fda.gov/cdrh_docs/pdf17/P170039d.pdf . Accessed June 16, 2019.
  2. U.S. Food & Drug Administration. FDA approves first artificial iris. https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm609291.htm . Accessed June 16, 2019.
  3. Snyder ME, Han DC. Prosthetic iris device implantation. In: Bradley Randleman, Iqbal Ahmed, editors. Intraocular lens surgery: Selection, complications and complex cases. New York, New York: Thieme; 2016.
  4. Alio JL, Al-Shymali O, Amesty MA, Rodriguez AE. Keratopigmentation with micronised mineral pigments: complications and outcomes in a series of 234 eyes. Br J Ophthalmol. 2018;102:742-747.
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  10. S Morcher. Surgeries with Morcher Aniridia Implants: Sulcus Ring - Type 96S. Available from: http://www.morcher.com/en/videos/aniridia-implants.html . Accessed June 17, 2019.
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  12. Srinivasan S, Ting DS, Snyder ME, Prasad S, et al. Prosthetic iris devices. Can J Ophthalmol. 2014;49:6-17.
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