A few years have passed since we last discussed iris prostheses in Ophthalmology Management (https://bit.ly/3bn2tju ). Back then, we were just on the heels of the FDA approval of the custom, flexible iris prostheses (HumanOptics AG, distributed in the United States by VEO Ophthalmics).

Happily, there has been a lot of progress since that time, and I’m glad to provide an update.

ACCESS

During the FDA study, US patients were only able to access the custom iris implant at one of the 12 study sites scattered across the country.

Since then, more than 100 US surgeons have become fully credentialed for placing the implant, and many others are in various stages of incorporating this technology into their surgical armamentarium, according to HumanOptics. This has been great for patients, who can now be treated closer to home, and great for surgeons, who are now able to provide these services to their iris-afflicted patients.

BILLING AND CODING

After the initial FDA approval and launch, few insurers covered the device or the surgery to implant it. In early 2020, a code was approved for ordering the device itself.

As of July 2020, we now have three approved CPT codes for both the device itself and for insertion:

• 0616T for custom iris device insertion alone
• 0617T for iris device insertion with cataract removal
• 0618T for iris device insertion with either secondary IOL placement or IOL exchange.

The custom, flexible iris prosthesis remains the only device available on the US market. An increasing number of insurers are recognizing the codes, though some carriers lag behind others; case-by-case advocacy is sometimes required.

PATIENT PROFILE

Insufficent pigment

So, who may need an iris prosthesis? Many disparate pathologies share a common final pathway of insufficient iris tissue or pigment. First, let’s discuss patients with insufficient pigment. This lack may be due to:

• Ocular/oculocutaneous albinism (partial or complete)
• Iris pigment epithelial atrophy (uveitic, herpetic, traumatic, post-surgical/uveitis-glaucoma-hyphema syndrome.

Insufficient tissue

The second pathway is patients with insufficient tissue. The causes fall into two catetories:

• Congenital — including congenital aniridia, Rieger syndrome and coloboma
• Acquired — including trauma, iridocorneal endothelial syndrome (ICE), intentional surgical defects (ie, post-melanoma excision) and iatrogenesis (ie, intraoperative floppy iris syndrome).

WHAT DO PEOPLE WITH IRIS DEFECTS NOTICE?

Light sensitivity

When more light enters the eye than should be the case by a normally functioning iris, this can lead to light sensitivity, varying from difficulty functioning in brightly lit spaces, such as a “big box” store, to inability to function outdoors in the sunshine and everything in between. Some people even have trouble looking at a computer monitor or a cellphone screen.

Interestingly, the relative size of the defect does not always correlate with the degree of symptoms; some have severe symptom with smaller defects and others with lesser symptoms have larger defects. Eyes with lighter color and less choroidal pigment seem to be more vulnerable than those with darker remaining iris tissue and more heavily pigmented choroid, though the individual variations in symptoms will often belie these generalizations as well.

Glare, arcs and halos

These phenomena tend to be present more in bright daylight or from headlights at night. Arcs and halos are especially common when the edges of an IOL are exposed, either in whole or in part, in the iris defect.

Monocular multiple images or shadow images

A few different reasons explain why some patients notice multiple monocular images. Below, I’ll discuss two.

If an aphakic space is exposed around the edge of either a subluxed natural lens or around the outside edge of an IOL, then light going through this space can create a second, blurred image. Often, this is seen as a shadow image around the primary image.

When there is one or more holes in the iris (in addition to the native pupil), a second image can be formed from light passing separately through that hole. The relative location of that image compared to the primary image often correlates with the relative location of the additional defects to the primary pupil. The number of images often matches the number of apertures. If the edge of an IOL splits an aperture, this may result in two images from that opening, so the number of images may be even larger than the amount of iris holes.

Multiplopia is especially common with single point sources of light against a dark background, such as a headlight or streetlight at night.

Contrast reduction

Contrast reduction is a phenomenon that is counterintuitive to understand. We see it most often in patients who have an exposed aphakic space around the edge of an implant lens. In patients with total aniridia, for example, they may have worse contrast reduction as a pseudophake than they did before cataract formation. This results from defocused light entering the eye along with the focused light that comes into the eye through the IOL. The defocused light washes out the image formed by the focused light.

I like to think about this like the effect one notices watching a movie at the theater when someone opens the door to the hallway and diffuse light enters the room. While the projector is still focused and delivering the same lumens to the screen, the subjective viewing experience is diminished.

IRIS DEVICES VS ALTERNATIVES

The plane of the opacity

The first factor that make the effect of iris devices different from opaque periphery contact lenses or corneal tattoo is the plane of opacity. Opaque contact lenses and corneal tattoo both create an opacity at the corneal plane. Accordingly, while they may reduce the total amount of light that enters the eye, some light will still enter through the iris defects, since light can obliquely cross the anterior chamber. On the other hand, with an iris prosthesis, the opacity rests directly at the native iris plane, preventing stray light from entering, except through the central pseudopupil.

Durability

Another difference is that an iris prosthesis is expected to last forever. Opaque periphery contact lenses, meanwhile, need periodic replacement. Tattoo dyes can fade over time and can migrate through the corneal lamellae from where they were initially placed.

Cosmesis

Finally, opaque periphery contact lenses are available in a fixed palette of colors. Tattoo dye colors are even more limited, and the location of their placement is much less refined. They are also viewed on the surface of the cornea, so the natural depth of the anterior chamber is obliterated. Custom iris prostheses, on the other hand, are matched to the specific eye, have a simulated iris texture, and are viewed through the cornea and anterior chamber just as the native iris is.

EXPECTATIONS AND BESPOKE DEVICES

Obtaining a template image

Because the devices are custom manufactured for each patient, a couple steps are unique to this process. The first is obtaining a template image: The device is hand colored from a hard copy image sent to the manufacturers. The quality of the image should demonstrate a color and brightness match to the unaffected fellow eye. I like to print the photos while in the exam room before dilation, to ensure that the patient, family and I all agree that the template is a good match.

If it does not look great on the first run, I digitally adjust the image and re-print until a satisfactory match has been achieved. Congenital aniridics can select from a “library” of photos that the investigator may have or select a high-quality image from a friend or family member.

Patience required, and maybe a re-check

The second unique factor in ordering an iris prosthesis is the patience they require on the part of the surgeon and the patient. Keep in mind that these devices are custom manufactured. The time from ordering to implantation typically takes a few months — or more. You may want to bring the patient back for a quick recheck before surgery if logistics for your patient stretches beyond 3 months, since, as we mentioned above, eyes that need iris prostheses typically have other comorbidities; further, either pressure issues or inflammation issues might have arisen in the interval between the original visit and surgery.

Incorporating into your surgical armamentarium

As we’ve said, the kinds of eyes that might need an iris prothesis have other comorbidities that can make these cases challenging. Some surgeons have great confidence in dealing with the complexities often seen in these cohorts, while others may not feel as comfortable with tougher cases. Surgeons who have already gained ample experience with capsular tension rings, scleral fixation of implants, pars plana approach to anterior vitrectomy, intraocular suturing and the like are most likely to find the techniques for iris prosthesis implantation within their comfort zone.

The distributor, VEO Ophthalmics, has developed a rather robust training program consisting of both online modules and a “dry” lab using surgical eye models designed specifically for the purpose of life-like practice with sample devices (SimulEye). These models can be used in one’s regular surgical facility with one’s regular surgical instrumentation for repeated practice in advance so that surgeons feel well prepared before their first case. Additionally, as with most things, it is often very helpful to talk the case through in advance with an iris device-experienced colleague to solicit additional nuances that may be more unique to each patient’s situation.

LIFE CHANGING

One of the more common comments we hear from patients following custom iris prosthesis placement is that the experience is “life changing.” These are typically very grateful and very happy patients. OM

About the Author

Michael E. Snyder, MD, is on the Board of Governors, Cincinnati Eye Institute, and is chair, Clinical Research Steering Committee and Professor of Ophthalmology, University of Cincinnati, School of Medicine.

Disclosures: Dr. Snyder reports relationships with VEO Ophthalmics and HumanOptics.