Prosthetic Iris Devices
Prosthetic Iris Devices
The first Prosthetic Iris Device was implanted by Dr. Choyce in 1956. It was intended to fill iris defects in patient suffering from traumatic iris defects, congenital aniridia, iris coloboma, herpetic iris atrophy, surgical iris loss, or ocular albinism among others in order to restore some of the functions of the iris. The iris acts as a diaphragm regulating the amount of light entering the eye; for instance, the amount of light entering an aniridic eye (limbal diameter 12.0 mm) is about 4-fold greater than the amount of light entering a 6.0 mm pupil. It also promotes depth of focus and limits spherical and chromatic aberrations.
Types of devices
Traditionally, there are 3 types of prosthetic iris devices:
- Iris lens diaphragm
- Endocapsular tension ring with fins
- Customized artificial iris such as Customflex from Humanoptics.
Burk et al, in a prospective case series of patients with iris defects who underwent prosthetic iris device implantation, reported that 79% of patients had improvement in their visual acuity and 96% reported reduction in glare.  In a prospective case series of 37 patients with traumatic iris defects, Aritificialiris by Humanoptics was implanted for iris reconstruction. After implantation, IOP and BCVA did not change significantly, contrast sensitivity increased significantly, and cosmetic disturbance and glare both improved significantly. Combined surgery of prostheteic iris device implantation with cataract extraction has also been shown to be safe in improving visual acuity and reducing photic symptoms.
In recent years, new prosthetic iris devices such as the Humanoptics Customflex foldable silicone iris device have become available in the market to improve cosmesis. This device is designed for either endocapsular use or sulcus implantation with transscleral sutures.
Potential complications following prosthetic iris devices vary depending on implant type and location of implantation. In a review of 25 patients implanted with prosthetic iris devices, 2 had transient postoperative hypotony, mild persistent inflammation in 1 eye, and macular edema and retinal detachment in one eye with recent severe trauma. Another review of 37 prosthetic iris implants reported 2 patients with dislocated or subluxed iris implants requiring surgical intervention, one patient had recurrent bleeding from the ciliary body that resolved spontaneously, and one patient had chronic inflammation, macular edema and corneal decompensation one year after implantation. One patient had a moderate increase in intraocular pressure that was adequately controlled on two pressure lowering medications 2 years following implantation.
Cosmetic Iris implants are not approved in the US by the FDA and are designed for implantation in the anterior chamber over the iris, unlike the previously mentioned prosthetic devices that are designed for sulcus or intracapsular placement. Many authors have reported cases where the cosmetic iris implant has lead to complications requiring explantation. Anderson et al. reported 2 cases that lead to severe complications such as hyphema, glaucoma that required explantation and other surgeries like trabeculectomy to control glaucoma. Arthur et al reported a case of uveitis glaucoma hyphema syndrome and corneal decompensation that followed the implantation of the device.  Hoguet et al published a case series of 14 eyes who had a cosmetic iris implant, it showed that the most common complications included uveitis, glaucoma, corneal edema, and decreased visual acuity. 
In cases of cosmetic iris implants, corneal decompensation may be secondary to trauma to the endothelium during implantation or chronic inflammation. The implant comes in close proximity to the iris leading to frequent rubbing that releases pigment and results in pigment dispersion and glaucoma. It may also impinge on the trabecular meshwork raising the intraocular pressure. Castanera et al examined some of the implants using scanning electron microscopy and noted that the surface of the implant is very irregular and rubs on the iris.
Prosthetic Iris device may be present in the anterior chamber or in the sulcus or bag depending on the type. Careful examination for anterior chamber pigment and inflammation is important, as well as gonioscopy, intraocular pressure and optic nerve exam. The cornea should also be closely examined for endothelial cell loss or decompensation.
Management of complications
Each secondary complication needs to be addressed. However, many times the first step is explantation. This is often required in cosmetic iris implants in the anterior chamber and very rarely in iris prosthetic devices in the sulcus or capsular bag. Explantation often requires cutting the implant into pieces after using viscocohesive material. Arjmand et al posted a video that shows a certain technique for explantation of cosmetic iris devices.
- Burk SE, Da Mata A., Snyder ME, Cionni RJ, Cohen JS, Osher RH, Prosthetic iris implantation for congenital, traumatic, or functional iris deficiencies. J Cataract Refract Surg, 2001. 27(11).
- Mayer CS, Reznicek L, Hoffmann AE. Pupillary Reconstruction and Outcome after Artificial Iris Implantation. Ophthalmology. 2016 May;123(5):1011-8.
- Snyder ME, Osher RH, Wladecki TM, Perez MA, Augsburger JJ, Corrêa Z. Results in Combined Cataract Surgery With Prosthetic Iris Implantation in Patients With Previous Iridocyclectomy for Iris Melanoma. Am J Ophthalmol. 2017 Mar;175:45-51.
- Anderson J, Grippo T, Sbeity Z, Ritch R. Serious complications of cosmetic NewColorIris implantation. Acta Ophthalmol., 2010. 88: p. 700-704.
- Arthur SN, Wright M., Kramarevsky N, Kaufman SC, Grajewski AL, Uveitis- glaucoma-hyphema syndrome and corneal decompensation in association with cosmetic iris implants. Am J Ophthalmol 2009. 148: p. 790-3.
- Hoguet A, R.D., Koplin R, Wu E, Raviv T, Aljian J, Seedor J, Serious ocular complications of cosmetic iris implants in 14 eyes. J Cataract Refract Surg, 2012. 38(3): p. 387-93.
- Castanera F, Fuantez Paez G., Ten P, Pinalla B, Guevara O, Scanning electron microscopy of explanted cosmetic iris implants. Clin Experiment Ophthalmol, 2010. 38(6): p. 648-51.
- Arjmand P, Gooi P., Ahmed I., Surgical technique for explantation of cosmetic anterior chamber iris implants. Cataract Refract Surg, 2015. 41: p. 18-22.
- Sathish Srinivasan, Ting D., Snyder M., Prasad S., Koch H., Prosthetic iris devices. Can J Ophthalmol, 2014. 49: p. 6-17.