Apart from its cosmetic function, the iris acts primarily as a diaphragm, regulating the amount of light entering the eye. In addition, the smaller the pupillary aperture, the greater the increase in the depth of focus. The iris also normally covers the edge of the lens, limiting related spherical and chromatic aberrations. The main symptom of iris absence or deficiency is glare or photophobia, which can occur even if only a small portion of the iris is affected.
Penetrating ocular trauma is a major cause of acquired iris tissue loss. Ophthalmic surgery rarely results in iris defects. Congenital pathology associated with a missing or deficient iris include aniridia, anterior segment dysgenesis, and coloboma. Functional deficiency can be a result of ocular albinism, irido–corneal–endothelial syndrome, herpetic iris atrophy, and traumatic mydriasis.
Eyes with an ineffective iris diaphragm often have other underlying problems that make their management a challenge. No method has been established as a gold standard for intraocular restoration of iris function.
Today, several prosthetic iris devices are available. Three by Morcher include a single-piece intraocular lens (IOL) with a black poly(methyl methacrylate) (PMMA) rim that substitutes for the missing iris (aniridia IOL type 67)1–3 and an endocapsular ring with a single-fin style (96G) for small defects or a multiple-fin style (50C) for occlusion of defects larger than 6 clock hours.4,5 The endocapsular rings can be inserted through 3.2 mm incisions, whereas the rigid aniridia IOL requires a 7.0 to 10.0 mm incision.
Another concept, the Iris Prosthetic System (IPS, Ophtec), is distributed by Polytech Ophthalmologie. It is available with a single (IPS SE) or double (IPS DE) occluding element (Figure 1) and in 4 colors. The overall diameter of each element is 10.5 mm. The IPS is designed for placement in the capsular bag. The elements alone or with other elements can cover small to complete iris defects. The IPS can be implanted in conjunction with a posterior chamber intraocular lens (IOL) and a capsular tension ring (CTR).
We describe 2 cases of persistent ocular inflammation, total retinal detachment, and hypotony after IPS implantation in eyes with occluding traumatic iris defects that were stable over a long period.
A 33-year-old woman sustained penetrating corneoscleral trauma with significant iris prolapse in the left eye by a piece of a shattering glass bottle. The prolapsed part of the iris was resected during the primary wound repair. No complications were observed postoperatively, although an intraocular foreign body was left untouched.
At a follow-up visit 2.5 years later, the uncorrected visual acuity was 20/200. The best spectacle-corrected visual acuity (BSCVA) was also 20/200 as a result of a scar through the visual axis in an otherwise clear cornea. The Rodenstock retinometer reading was 20/20. There was no sign of inflammation in the anterior chamber or the remaining iris. The lens was mildly opacified but stable in its normal position. On fundus examination, a piece of glass partly touched in the ciliary body and the retina was normal.
Sixteen years after the trauma, the situation was the same and there were no signs of hypotony. The patient had iris prosthesis implantation associated with cataract surgery at another clinic. A single and double element from the IPS were implanted with a CTR and a foldable posterior chamber IOL.
Eight months later, the patient was referred with painful, chronic, recurrent hemorrhagic anterior uveitis that was refractory to antiinflammatory medications (Figure 2). Visual acuity was light perception, and the intraocular pressure (IOP) was 4 mm Hg. There was fibrotic tissue proliferation with erythrocytes in front of the iris prosthesis that extended to the anterior chamber angle. The posterior aspect of the IOL was completely covered by the fibrotic lens capsule. Fundoscopy was not possible because of blood cells behind the lens capsule and severe infiltration of the vitreous. A retinal detachment was diagnosed ultrasonically. The globe was enucleated in view of the nearly blind, painful eye and poor visual prognosis.
The enucleated globe was opened at the equator, revealing a funnel-shaped retinal detachment. Looking from the back on the iris–lens plane, a closed thick cyclitic membrane was seen with the anterior retina adhering to it. Extensions of this membrane had caused traction on the ciliary body, resulting in its detachment and ocular hypotony (Figure 3). Anterior to the cyclitic membrane, the IPS elements, IOL, and CTR were ensheathed by the fibrotic lens capsule and membranes. This proliferative tissue also invaded the cavities between the implanted devices. The glass splinter was also enclosed by fibrotic membrane (Figure 4). From the anterior aspect, a retrocorneal membrane was seen just in front of the artificial iris–lens diaphragm. Extensions of this retrocorneal membrane were partly obstructing the anterior chamber angle, particularly in the area where the glass splinter had penetrated the iris and zonular fibers. No remnants of the lens capsule were detectable anterior to the IPS; that is, the IOL and CTR were fixated in the ciliary sulcus anterior to the contracted lens capsule (Figure 5). Figure 6 shows the foreign material including the glass splinter.
A 28-year-old man sustained a penetrating corneoscleral injury with partial iris loss in the left eye in a car accident. He had 38 uneventful years after the trauma with no signs of hypotony.
Cataract surgery with implantation of an IPS and a posterior chamber IOL was performed elsewhere. The patient noted temporary improvement in the quality of vision after cataract removal. However, in the postoperative period, a retinal detachment developed that was repaired after 8 weeks with combined scleral buckling surgery and pneumatic retinopexy. Four weeks and 8 weeks later, recurring retinal detachments required 2 additional sessions of pars plana vitrectomy with endotamponade using F6H8 (a semifluorinated alkane with a specific gravity of 1.3) and silicone oil, respectively.
When the patient was referred to our university clinic 12 weeks after the final surgical intervention, the BSCVA was reduced to hand motions and the IOP was 8 mm Hg. The cornea was clear in the region of silicone oil–endothelial contact. The peripheral cornea was mildly opacified by stromal edema. There was sectoral iris loss beneath a corneal scar close to the limbal area at 5 o'clock that was subsequently occluded by IPS element insertion. Extensive exudative membrane formation developed on the anterior surface of the iris prosthesis and in the pupillary plane postoperatively (Figure 7). The IOL was not dislodged but was almost completely surrounded by the fibrotic lens capsule. Total retinal detachment was diagnosed with ultrasound.
These cases suggest that implantation of an IPS combined with cataract surgery can trigger decompensation of posttraumatic eyes that have been stable for a long time. To our knowledge, this is the first description of sight-threatening complications after implantation of an IPS. A computerized search of the PubMed database (National Library of Medicine) did not yield any published work on the IPS system before June 2002. However, there are some promising reports of aniridia IOLs that include short-term and long-term follow-ups, although slight persistent intraocular inflammation was common and cystoid macular edema and secondary glaucoma were observed.1–8
Among the many factors that may have contributed to the complications we observed, the trauma of the implantation appears significant. Evidently, eyes whose anterior segment is traumatically disorganized to a large extent and that have had surgery are likely to have an increased tendency toward proliferative postoperative inflammation. Implanting any foreign material adds to this tendency. Placement of IOLs fully in the capsular bag has a less negative effect on the integrity of the blood–aqueous barrier (BAB) than ciliary sulcus fixation.9 That the IPS and IOL were sulcus fixated in Case 1 and the iris prosthesis was not completely separated by the lens capsule from the iris in Case 2 could explain the long-term and severe BAB breakdown. It seems likely that the proliferation started from reactivated dormant fibroblasts at the original site of damage to the uveal tract and lens capsule as the membranes were thickest there. Iris-tissue-derived “cocoon membranes” are known to occur with fibrovascular proliferation and encasement of the IOL after surgical trauma and prosthesis and IOL contact with the iris.10
The long-term biocompatibility of the IPS, which consists of molecularly bound color pigment in PMMA, must be taken into account, especially in cases similar to the first one, in which the surface area of all implanted IPS elements was roughly 4 to 5 times larger than that of the IOL.
Another factor could be the heavy implanted material, which may have irritated the uveal tract by traction on the lens zonules, as proposed by Uusitalo and Uusitalo.11 They report severe complications after treating traumatic aphakia with a custom sutured combined iris prosthesis–IOL. Additional intraocular operations were required to explant or reimplant the luxated lenses. They also observed secondary glaucoma but no retinal detachment or critical uveitis.
Perhaps the minor hemorrhages noted clinically and on histopathology in Case 1 were caused by erosions of the ciliary body by the IOL, CTR, and IPS, which may have also contributed to intraocular inflammation causing proliferation and membrane formation.
Correcting symptomatic iris defects is rewarding; however, the IPS should be used with caution. Based on the literature and our experience, the Morcher aniridia IOL and the endocapsular ring prosthetic devices, although not completely satisfactory, seem to be safer in eyes in which aphakic contact lenses are difficult to fit. The 2 cases presented also have implications for placing implants of considerable dimensions in the anterior segment.
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