In addition to the lack of an iris diaphragm, other reasons exist for the reduction in visual acuity that is common in congenital aniridia. These include hypoplasia of the macula, optic nerve, or both; glaucoma; conjunctivalization of the cornea; and cataract.1–11 Many attempts have been made to compensate for the lack of the iris diaphragm, including eyelid surgery, use of colored contact lenses, and coloring the cornea.1,12,13 Choyce2 reported the implantation of colored diaphragm intraocular lenses (IOLs) in the anterior chamber of phakic and aphakic eyes with traumatic aniridia, albinism, and traumatic mydriasis; however, he did not present long-term follow-up data. Conventional IOL implantation in eyes with congenital aniridia has been reported in several studies.7,14,15 In 1991, a newly designed black diaphragm aniridia IOL was implanted for the first time in eyes with congenital aniridia after cataract surgery. Encouraging short-term results were reported in 1994.16 Here, long-term data from a larger patient group are presented.
Patients and Methods
Between 1991 and 1998, the black diaphragm aniridia IOL was implanted in 26 eyes of a consecutive patient series with congenital aniridia. Four eyes with transscleral suturing of the IOL were excluded as well as 3 eyes with combined penetrating keratoplasty. A homogenous group of 19 eyes was studied to evaluate the long-term outcomes after extracapsular cataract extraction (ECCE) or phacoemulsification and implantation of the black diaphragm IOL in front of the capsular bag. These 19 eyes were in 14 patients with a mean age of 30 years (range 10 to 59 years) at the time of surgery. Nine patients had IOL implantation in 1 eye only, and 5 had bilateral IOL implantation. All eyes had advanced cataract. Ten of the 19 eyes had mature cataract or very brown nuclei.
A preoperative examination included best corrected visual acuity, slitlamp evaluation of the anterior eye segment, applanation tonometry (Goldmann) when possible, ophthalmoscopy, and if necessary, ultrasound, evaluation of the vitreous and the retina. If the cornea was too irregular for applanation tonometry, intraocular needle tonometry was done to obtain reliable values.17 Implantation of the black diaphragm aniridia IOL was only performed if intraocular pressure (IOP) was preoperatively well controlled medically or surgically. If possible, endothelial cell density was determined with the Robo Noncon specular microscope.
Before surgery, corneal epithelial disorders; corneal pannus; cataract; hypoplasia of the macula, optic nerve or both; and nystagmus were present in all 19 eyes. Clinically detectable glaucoma was present in 5 eyes.
In 10 adult eyes, surgery was performed using retrobulbar anesthesia. Adult patients refusing retrobulbar anesthesia and all children received general anesthesia (9 eyes).
Extracapsular cataract extraction was performed in 10 eyes with mature cataract or a very hard nucleus and phacoemulsification in 9 eyes with a softer nucleus. The ECCEs were performed after a corneal incision was made over 170 degrees. The anterior lens capsule was opened using an envelope technique. Nucleus expression was followed by capsular bag cleaning and anterior lens capsule excision. The IOL was implanted in front of the capsular bag. The cornea was closed with a running 10-0 nylon suture. Phacoemulsification was performed through a 4.0 mm corneal incision with a continuous curvilinear capsulorhexis (CCC). After phacoemulsification, the corneal incision was enlarged to the same length as in the ECCE cases to allow implantation of the large IOL. The only difference between the ECCE and phacoemulsification groups was that after the CCC, the anterior lens capsule was not torn radially.
In both techniques, 170 degree corneal incisions were necessary to implant the large IOL, with diaphragm diameters between 10.0 and 11.0 mm. A corneal (not a corneoscleral) approach was used to minimize the risk of intraoperative or postoperative hemorrhage.
If bilateral surgery was necessary, the second eye was not treated before an uneventful course of at least 6 months was observed in the first eye.
In cooperation with Morcher, the black diaphragm aniridia IOL was modified several times. The only IOL type implanted since 1995 is type 67G, which has a diaphragm diameter of 10.0 mm, an optic diameter of 5.0 mm, and a haptic diameter of 12.5 mm (Figure 1, Table 1).
Postoperatively, prednisolone acetate 1% and gentamicin eyedrops were administered 5 times daily. After 4 days, the gentamicin was withdrawn and the prednisolone acetate tapered to 1 drop over 3 months. It was recommended that the prednisolone acetate be taken daily over the long term.
The same examinations as preoperatively were performed 1 and 3 months postoperatively and once a year thereafter. If possible, fluorescein angiography of the macula was done. The haptic positions were determined via gonioscopy, or if not possible, via ultrasound biomicroscopy.18 In addition, patients were asked to compare preoperative with postoperative glare. All patients were followed prospectively. Mean follow-up was 46 months (range 12 to 84 months).
Aniridia Lens Model
Because of initial difficulties in implanting the first large IOL types, several modifications were judged necessary until the prototype was established (Table 1). The most recent model, 67G, could be guided easily into the eye in front of the capsular bag. No correlation between the different types of the black diaphragm IOL or the haptic position and the extent of persistent intraocular inflammation, glaucoma, cystoid macular edema (CME), or endothelial cell loss was observed (Table 2).
Visual Acuity and Glare
Visual acuity improved in 14 of the 19 eyes (Figures 2 and 3, Table 2). It remained unchanged in 1 eye and deteriorated slightly in 4 eyes. Eleven of 14 patients (79%) reported reduced glare. Three patients did not experience differences between preoperative and postoperative glare.
Slight aqueous flare with a few cells in the anterior chamber in all 19 eyes was observed over the long term; thus, the long-term daily drop of prednisolone acetate. Because of nystagmus, the objective values of this presumed vessel leakage could not be determined by a flare meter.
Deterioration in glaucoma postoperatively occurred in 4 of the 5 eyes with preoperative glaucoma. The glaucoma was controlled medically in 2 eyes and surgically (trabeculectomy, cyclodestruction) in the other 2 eyes. Four of the 14 eyes without a preoperative glaucoma history developed postoperative chronic glaucoma, which was controlled medically in 2 eyes and surgically (trabeculectomy, cyclodestruction, IOL explantation) in 2 eyes (Table 2). In 1 of the latter eyes, trabeculectomy and subsequent cyclodestruction were performed; in the other eye, only cyclodestruction was done. These procedures did not control IOP, and IOL explantation was done to lower the pressure. Thereafter, medical control of IOP was possible in both eyes.
Six of 9 contralateral eyes not having surgery had a history of glaucoma at the first preoperative visit. Postoperatively, 2 of these eyes had a deterioration that was controlled medically during follow-up.
Cystoid Macular Edema
Fundoscopy alone did not reveal CME in any eye. Because of nystagmus, corneal epithelial disorders, or both, fluorescein angiography could be performed in only 11 eyes; of these, 2 (18%) had CME (Table 2).
Endothelial Cell Loss
Determinations of endothelial cell density could be performed in only 11 eyes because of nystagmus, corneal surface disorders, or both. There was a less than 15% drop in endothelial cell density in 8 eyes and chronic endothelial cell loss in 3 eyes (Table 3).
Corneal surface disorders and a preoperative pannus of at least 1.0 to 2.0 mm in the entire circumference were present in all 19 eyes preoperatively. A postoperative deterioration in the surface disorders occurred in 4 eyes; 2 with and 2 without pannus progression(Table 2).
Posterior Lens Capsule
Posterior lens capsule rupture occurred in 1 patient. Because of fibrous posterior capsule opacification (PCO), a surgical posterior capsulotomy in combination with an anterior vitrectomy was performed in 4 eyes simultaneously with cataract surgery, especially in children and in adults with extensive nystagmus. Of the remaining 14 eyes, 12 developed PCO, which was treated in 11 eyes with a neodymium:YAG (Nd:YAG) laser using topical anesthesia.
Almost 75% of our patients with congenital aniridia and cataract had increased visual acuity after implantation of the black diaphragm aniridia IOL. Neither this percentage nor the extent of the increase can be compared with “normal” cataract patients because congenital aniridia is accompanied by several abnormalities, such as hypoplasia of the macula, optic nerve, or both; nystagmus; and amblyopia. These conditions severely limit postoperative visual acuity. For these eyes, an increase in acuity (e.g., from 0.05 to 0.01) is a significant improvement. Almost 80% of our patients had reduced glare postoperatively. Thus far, the main goal of implanting this IOL has been achieved in most of the patients. However, this functional improvement was achieved at the (presumed) risk of a variety of complications in some patients.
The main postoperative problem was chronic IOP elevation in 8 of 19 eyes (42%). In 4 of these eyes, chronic glaucoma had been diagnosed and well controlled preoperatively. In the other 4 eyes (29% of the 14 eyes without evident preoperative glaucoma), chronic glaucoma became evident after implantation of the black diaphragm aniridia IOL. In 2, glaucoma could only be controlled by trabeculectomy, cyclodestruction, and explantation of the aniridia IOL.
Although glaucoma is a common endogenous complication of congenital aniridia, the blood–aqueous barrier (BAB) may be altered by the black diaphragm aniridia IOL, accelerating glaucoma progression. There are several possible reasons for chronic alteration of the BAB barrier:
- The IOL is too large to be implanted in the capsular bag. Thus, the haptics and the diaphragm are in direct contact with uveal remnants in front of the capsular bag and may cause continuous irritation.
- Implantation of this IOL, especially of the haptics, in front of the capsular bag in aniridia patients is much more difficult than in conventional cataract surgery. About 65% of the identifiable haptics were not found in the ciliary sulcus but in the angle of the anterior chamber or on the pars plana. The haptic position in the angle of the anterior chamber in front of iris remnants may directly trigger accelerated dysfunction of the endogenous abnormal trabecular meshwork. A correlation between identifiable “dislocated” haptics and the appearance or extent of postoperative glaucoma complications, CME, and endothelial cell loss was not observed, however. The position of 15 haptics (39%) could not be determined.
- Although not proven by our data, the black diaphragm IOL might have greater mobility than conventional IOLs after sulcus implantation behind the intact iris of “normal” eyes. Therefore, firm transscleral suturing of the black diaphragm IOL in eyes with congenital aniridia in front of an intact lens capsule might be considered in the future.
- The BAB in eyes with congenital aniridia may be much more vulnerable to all types of trauma than that in normal eyes.
Beside being responsible for at least part of the glaucoma problems, BAB breakdown was probably also responsible for the development of CME in 2 of 11 eyes (with fluorescein angiography) and chronic endothelial cell loss in 3 of 11 eyes (probably only 2 because the cell loss in eye 6 may also have been caused by surgical trauma). Therefore, if the patient was not a corticosteroid responder, topical corticosteroids were administered in a low dose over the long term in an attempt to ameliorate BAB breakdown using a presumably innocuous therapeutic measure.
The question of whether cataract extraction with a conventional intracapsular IOL would result in comparable visual improvements without the described complications remains unanswered. This would have to be ascertained in a prospective randomized multicenter study. Because patients with congenital aniridia are relatively few, such a study would take many years.
In summary, implantation of the black diaphragm aniridia IOL improved visual acuity significantly in most of the patients with congenital aniridia. Glaucoma was the greatest postoperative problem, and the suspicion that glaucoma progression in some of these patients may be accelerated by the large aniridia IOL cannot be excluded. Another problem may be CME in some patients. Because of the variety of difficulties in these patients, the aniridia IOL should not be implanted in eyes with clear lenses; such surgery should only be performed if advanced cataract is present. Close postoperative follow-up is required to control these problems over time, and one should be cautious about implanting the aniridia IOL in eyes with existing glaucoma.
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