Prosthetic Iris Devices (PID) are medical devices implanted intraocularly to replace or assist iris function in congenital or acquired iris defects or dysfunction.
Prosthetic iris devices are broadly divided into functional prosthetic iris devices and cosmetic implants. Functional prosthetic iris devices are used for therapeutic purposes such as aniridia, trauma, congenital anomalies, and iris atrophy. In contrast, cosmetic implants are additionally placed in the anterior chamber solely to change eye color; they lack evidence of safety and are unapproved in many countries.
The first implantation of a prosthetic iris device was reported in 1956 by Peter Choyce as an anterior chamber lens.4) In 1994, Sundmacher et al. and Reinhard et al. implanted black diaphragm IOLs for congenital and traumatic aniridia, which is considered the starting point of modern prosthetic iris devices.4)
Aniridia Ring
Representative example: Morcher 50E
Structure: Capsular tension ring base with 8 light-blocking panels
Placement: Endocapsular (within the lens capsule)
Features: Complete iris diaphragm composed of two rings
Note: Morcher ceased marketing activities at the end of 2020 4)
Iris Lens Diaphragm Type
Representative example: Black diaphragm IOL
Structure: Iris diaphragm integrated with IOL
Placement: In-the-bag or scleral fixation
Features: Simultaneously supplements IOL and iris function
Indications: Traumatic aniridia with lens extraction
Custom Flexible Artificial Iris
Representative example: Customflex Artificial Iris (HumanOptics)
Structure: Silicone, custom-ordered and moldable
Placement: In-the-bag, ciliary sulcus, or scleral fixation
Features: Flexible design insertable through a 2.6 mm incision
Note: Not approved in Japan (as of 2024)
Main symptoms reported by patients eligible for functional artificial iris devices.
| Assessment Item | Details |
|---|---|
| Extent of iris defect | Partial or total defect, unilateral or bilateral |
| Capsular bag status | Essential for determining feasibility of in-the-bag fixation |
| Ciliary sulcus condition | Assessment for ciliary sulcus fixation |
| Corneal endothelial cell count | Reference values for pre- and postoperative monitoring |
| Intraocular pressure | Confirmation of concurrent glaucoma |
Functional artificial iris devices are primarily intended to significantly improve photophobia. Reports on patients with albinism indicate that photophobia dramatically improves after surgery, and adaptation to light environments in daily life is enhanced. 4) Vision may improve if cataract surgery and IOL implantation are performed simultaneously. However, if there are central issues such as macular hypoplasia (common in albinism), there are limits to visual improvement.
Cosmetic anterior chamber implants (such as NewColorIris and BrightOcular) are additionally implanted on the anterior surface of the iris, and the following serious complications have been reported.
The following examinations are necessary for determining the indication for artificial iris device surgery and for preoperative planning.
Corneal endothelial cell examination (specular microscopy): Artificial iris device surgery poses a risk to the corneal endothelium. Preoperative and postoperative monitoring of corneal endothelial cell count is essential. Even after functional artificial iris device implantation, the corneal endothelial cell count may decrease over time. 2)
Anterior segment OCT (AS-OCT): Provides detailed evaluation of the extent of iris defect, remaining capsular status, and anterior chamber angle structure. It is also useful for measuring decentration of cosmetic implants. 1)
Intraocular pressure measurement (Goldmann applanation tonometry): For early detection of increased intraocular pressure due to pigment dispersion, angle closure, or trabecular meshwork damage.
Gonioscopy: Evaluates the degree of pigment deposition, peripheral anterior synechiae (PAS), and angle closure. Important for understanding the mechanism of increased intraocular pressure caused by cosmetic implants. 1)
You should see an ophthalmologist early to discuss treatment options, including implant removal. In one case report, neovascularization grew over the cosmetic implants, and intraocular pressure reached 45/30 mmHg in both eyes, requiring emergency implantation of Baerveldt glaucoma drainage devices in both eyes. 5) Complications can develop several years after surgery, so long-term follow-up is important.
Endocapsular fixation: The artificial iris device is implanted into the capsular bag simultaneously with cataract surgery. A technique has been developed in which two Morcher 50E aniridia rings are stacked and inserted together (stack technique). The conventional sequential insertion method carried a risk of ring segment interdigitation, but the stack technique avoids this risk. 4)
In a report of a 62-year-old man with albinism who underwent simultaneous implantation of two Morcher 50E rings using the stack technique, photophobia improved dramatically after surgery, and he no longer needed tinted glasses indoors. Postoperative UDVA was 20/160 in the right eye and 20/120 in the left eye (limited by foveal hypoplasia). No complications. 4)
Scleral fixation without capsule support: A combination with sutureless scleral fixation (Yamane technique) using the HumanOptics Customflex Artificial Iris has been reported. A 17-year-old male (traumatic aphakia and aniridia) underwent the AI-IOL sandwich method, in which the Customflex AI and a Kowa Avansee Preset UV IOL were integrated and fixed using Yamane-style intrascleral fixation. Postoperative logMAR CDVA of -0.10 was achieved. 3)
Bilateral implantation of Customflex Artificial Iris: In three patients with iris defects who underwent bilateral implantation, all were satisfied with the cosmetic results, and CDVA was maintained or improved. Contrast sensitivity improved in two of the three patients. One patient developed macular edema postoperatively, which was treated with Ozurdex (dexamethasone intravitreal injection). 2)
In Japan, the HumanOptics Customflex Artificial Iris has not been approved (as of 2024), making its use in routine clinical practice difficult. The aniridia ring (Morcher type) also requires confirmation of its domestic approval status. As alternatives, methods such as iris suturing or using an anterior chamber IOL as iris support may be selected. Please consult an ophthalmologist for the latest approval status.
Cosmetic iris implants (such as NewColorIris and BrightOcular) are implanted on the anterior surface of the iris and cause complications through the following mechanisms.
Pigment dispersion syndrome: The sharp edges or irregular surfaces of the implant mechanically rub against the iris, causing pigment to detach and disperse. Scanning electron microscopy (SEM) analysis of explants has confirmed surface irregularities and sharp edges. 1) The dispersed pigment accumulates in the trabecular meshwork, obstructing aqueous humor outflow and elevating IOP.
Decrease in corneal endothelial cells: Chronic inflammation in the anterior chamber, aqueous humor turbulence, and physical contact with a decentered implant damage the corneal endothelium, reducing the number of corneal endothelial cells. In one case, the corneal endothelial cell count decreased to 1268/1122 cells/mm² in both eyes after 15 years. 1)
Angle closure and peripheral anterior synechiae formation: The edge of the implant contacts the anterior chamber angle structures (trabecular meshwork, Schlemm’s canal), forming peripheral anterior synechiae (PAS). This chronically impairs aqueous humor outflow. 1)
Decentration of the implant: Over time, the implant shifts from the pupillary axis. In one case after 15 years, decentration of 475 μm temporally and 238 μm superiorly in the right eye, and 308 μm superiorly and 15 μm temporally in the left eye was reported. Greater decentration tends to be associated with higher IOP and earlier onset of complications. 1)
Neovascularization: In a state of extremely elevated intraocular pressure (45/30 mmHg in both eyes), ocular ischemia occurs, and neovascularization appears in the anterior chamber angle. The first reported case of direct neovascular proliferation on a cosmetic implant was published in 2025. 5)
When iris pigmentation is absent (albinism) or the iris itself is missing (aniridia), the amount of light passing through the pupil cannot be properly regulated. Excessive light stimulation to the retina causes photophobia and glare. Additionally, because the pupil is nearly maximally dilated, aberrations in the peripheral lens are large, reducing image quality. Artificial iris devices replace this “diaphragm” function. 4)
A technique of simultaneously stacking two Morcher 50E aniridia rings has been shown to eliminate the risk of segment entanglement compared to conventional sequential insertion. However, Morcher ceased sales and marketing of aniridia implants at the end of 2020, so future availability is uncertain. 4)
The combination of sutureless scleral fixation (Yamane technique) and the Customflex Artificial Iris is expected to accumulate cases as a new approach suitable for extracapsular support. For trimming the Customflex AI using this method, white-to-white (WTW) measurement ±0.5 mm is recommended. 3)
The HumanOptics Customflex Artificial Iris can be customized in color and shape based on a photograph of the patient’s healthy eye. High patient satisfaction has been reported for cosmetic restoration after trauma. Further improvements in biocompatible materials and manufacturing precision are expected in the future.
In response to the increasing number of complications from cosmetic iris implants, the medical community is calling for stricter regulation from ethical and medical perspectives. Given the lack of long-term safety data and the risk of serious complications, the risks of these devices are currently considered to outweigh the benefits. 1)
Queiruga-Piñero J, Parra-Rodríguez T, Rodríguez-Uña I. Long-term complications of cosmetic iris implants. BMC Ophthalmol. 2022;22:459.
Mayer CS, Reznicek L, Hoffmann AE. Bilateral artificial iris implantation in patients with bilateral iris defects. Am J Ophthalmol Case Rep. 2021;22:101065.
Muth DR, et al. Novel surgical technique of sutureless artificial iris and intraocular lens scleral fixation. Am J Ophthalmol Case Rep. 2022;26:101478.
Rabinovitch DE, Buhrmann R, Varma DK. Stacked implantation of two prosthetic iris devices for patients with iris defects: a modified surgical technique. Am J Ophthalmol Case Rep. 2023;32:101921.
di Geronimo N, Brambati M, Viola F. Neovascular proliferation over a cosmetic artificial iris implant. Case Rep Ophthalmol. 2025;16:87-92.
