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Up Front | Sep 2007

A Subluxated Traumatic Cataract With a Fixed Dilated Pupil

After careful surgical planning, complications can be minimized.

Anterior segment surgery involving a cataract in eyes such as the case we present herein—a fixed dilated pupil, significant lens subluxation, anterior capsular fibrosis, zonular dialysis, and vitreous prolapse into the anterior chamber—poses a significant challenge. In the recent past, such cases were typically associated with a significant risk of intra- and postoperative complications. Advances in viscoelastics, sutured capsular tension rings (CTRs) or segments, and phacodynamics now make such surgery possible. With careful planning, complications may be minimized. Herein, we report an illustrative case of small-incision complex anterior segment reconstructive surgery involving phacoemulsification and a limited anterior vitrectomy with insertion of a sutured capsular tension ring segment (CTS), artificial iris segments, and an IOL.

CASE REPORT
A 53-year-old white male presented with a longstanding history of a painless but visually compromised right eye (ie, count-finger vision) secondary to severe blunt trauma with an elastic bungee cord in 1989. This injury resulted in a complete and spontaneously resolving hyphaema that left a permanent widely dilated pupil with an atrophic iris. The crystalline lens was subluxated and cataractous, with moderate zonular dehiscence and vitreous extension into the nasal anterior chamber. Postinjury, the eye exhibited elevated intraocular pressure (IOP).

The patient's past medical and ocular history were unremarkable, however, there was a positive maternal history of retinal detachment. He was on no ophthalmic or systemic medication and was reviewed by ophthalmologists between 1991 and 2004. The general consensus was, despite poor vision in his right eye, that the surgical risks outweighed the potential benefits. Since the corrected vision in his contralateral eye was excellent, intervention was postponed.

The patient visited our center in 2005, complaining of significant photophobia and reduced vision associated with advanced cataract and the widely dilated pupil. BSCVA was counting fingers at 1-meter OD and 6/4.5 OS. Slit-lamp biomicroscopy revealed a fixed dilated pupil (9.5 mm) with an atrophic iris. An inferotemporally subluxated cataractous lens was associated with vitreous prolapse medially in the anterior chamber via zonular dehiscence (through greater than 120º superonasally). There was moderate phacodonesis, anterior capsule fibrosis, and an IOP of 18 mm Hg. Examination of the left eye revealed early lenticular opacification and an IOP of 17 mm Hg. Fundoscopy revealed a healthy macula, but minor optic nerve asymmetry was observed with a cup-to-disc ratio of 0.4 OD compared with 0.3 OS. This was possibly related to the previous blunt injury and period of elevated IOP. There was a subtle grade 1 relative afferent pupillary defect in the right eye.

Orbscan II corneal topography (Bausch & Lomb, Rochester, New York) revealed essentially normal keratometric topography maps, with a degree of inferior steepening in the left versus right eye. Central pachymetry was 574 µm OD and 573 µm OS. Keratometry measurements in the right eye were 43.83 D at 14º and 44.88 D at 104º (IOLMaster V.3.01; Carl Zeiss Meditec AG, Jena, Germany). Immersion ultrasound measurement demonstrated axial lengths of 24.7 mm in both eyes (OcuScan; Alcon Laboratories, Inc., Fort Worth, Texas). Using the SRK/T formula and aiming for a myopic residual correction, the suggested SA60AT (Alcon Laboratories, Inc.) IOL power was 17.00 D, for a mean target spherical equivalent of -0.48 D. No correction of corneal astigmatism was planned.

After discussion and informed consent, the proposed surgical intervention included phacoemulsification or conversion to extracapsular cataract surgery; limited anterior vitrectomy; sutured CTS, or scleral sutured IOL; and either an IOL with iris segments or an aniridia IOL. Surgical planning included the proposed use of iris hooks and sutured CTR/CTS to control and position the capsule. The patient underwent a complex uncomplicated cataract extraction that yielded good visual and symptomatic results.

SURGICAL TECHNIQUE
General anaesthesia was used. First, a conjunctival flap was raised in the superonasal quadrant. A partial thickness, 300-µm, triangular scleral flap was created (Figures 1A and B) using a guarded diamond knife to incorporate the planned site (ie, approximately 1.5 mm from the limbus). Here, the prolene suture for the scleral-sutured CTR/CTS would emerge between 1 o'clock and 1:30 o'clock. With a 15º blade, four paracenteses were made in the superior and inferior quadrants (Figure 1C). Using a diamond knife and a 3-mm microkeratome, a 3-mm, three-step, inferotemporal clear corneal incision was made in the axis of, but opposite to, the area of maximum zonule weakness (Figure 1D).

The small volume of vitreous extending through the zonular dehiscence and into the nasal anterior chamber was reduced with sodium hyaluronate 1.4% (Healon GV; Advanced Medical Optics, Inc., Santa Ana, California), injected to fill the anterior chamber and stabilize the compartment. To minimize tearing out of the anterior capsule, a small, slightly nasally displaced, 4-mm, continuous curvilinear capsulorrhexis was created using a sharp cystotome (Figure 1E). The capsulotomy margin was then utilized to centralize the crystalline lens for phacoemulsification and mimimize the risk of further vitreous prolapse through the zonular dehiscence. Two iris hooks were inserted through the peripheral cornea to support the capsule margin at the 1 and 4 o'clock positions, concurrent with regions of zonular weakness (Figure 1F). The length of the iris hooks was shortened, avoiding anterior capsular tear, until the crystalline lens was centered. Gentle hydrodissection was achieved with balanced salt solution (BSS; Alcon Laboratories, Inc.) (Figure 2A). Before commencing phacoemulsification, the capsule periphery in the area of the dehiscence was secured at 4 o'clock with a CTS (Morcher 6E; Morcher GmbH, Stuttgart, Germany) and a 10–0 polyprolene (Prolene; Ethicon, Inc., Piscataway, New Jersey) double-ended suture temporarily secured via the limbus (Figures 2B through D).

Once the lens was securely positioned—via the CTS and two iris hooks—no vitreous was found in the anterior chamber, and phacoemulsification was performed with low flow and power, in the direction of zonular dehiscence. The moderately dense nucleus was managed by a slow, careful, single groove and chop technique (Figure 2E). The cortex was readily aspirated, except in the area supported by the CTS, where it was removed with hydration and gentle tangential aspiration (ie, along the axis of the segment rather than radial or centripetal aspiration).

Once the capsular bag was completely clear of cortical material and confirmed to be securely suspended by the iris hooks and CTR, it was filled with viscoelastic (Figure 2F). Two Morcher 50C (Morcher GmbH) iris segment tension rings (Figures 3A and B) were inserted into the bag and rotated, greatly reducing the pupillary aperture (approximately 5-5.5 mm) (Figure 3C). The CTS was repositioned and resecured to centralize the capsular bag and iris segments (Figure 3D). A 10–0 prolene was knotted and buried under the previously created scleral flap, and the flap and overlying conjunctiva were closed with an 8–0 absorbable vicryl suture. An acrylic posterior chamber IOL (SN60AT, Alcon Laboratories, Inc.) was injected and carefully maneuvered to sit in the capsule, behind the iris segments and against the posterior capsule. This reduced the potential for posterior capsular opacification (Figures 3E and F). The capsulorrhexis was then enlarged to approximately 5 mm, and Healon GV was slowly aspirated to facilitate removal of any vitreous that might nasally enter the anterior chamber.

A small knuckle of vitreous was detected at approximately 3- to 4 o'clock, in the area of zonular absence. It was easily excised using a two-port anterior chamber vitrectomy technique. The anterior chamber was reformed with BSS, and the IOL/capsule complex was secure and well centered. Paracenteses were hydrated with BSS, and the cornea was closed with a temporary single 10–0 vicryl suture at 8 o'clock. Subconjuctival dexamethasone and cephazolin were administered (Figures 4A through D).

There were no intraoperative or immediate postoperative complications. Postoperative medications included prednisolone acetate 1% twice hourly and chloramphenical four times daily. On postoperative day 1, the patient's unaided vision was 6/18 (20/60) and improved to 6/12 (20/40) with a potential pinhole acuity of 6/7.5 (20/25) and a dramatic subjective improvement in glare tolerability at 1 week. Four months postoperative, the patient's unaided vision was 6/12 (20/40), with a BSCVA of 6/7.5 (20/25) and a refractive error of -0.25/ -1.00 X 175. The IOP was 17 mm Hg, and other examination findings were unchanged from the preoperative assessment. The Morcher iris segments were in a good position, with a generally contiguous diaphragm overlapping the edge of the IOL. There was no evidence of phacodonesis or zonular dialysis, although some minor posterior capsular thickening was observed.

DISCUSSION
This case represents challenging surgery for several reasons. The affected eye had a large fixed dilated pupil and significant phacodonesis associated with extensive zonular compromise through 120º superonasally and prolapse of vitreous medially into the anterior chamber. These factors complicate capsulorrhexis and increase the risk of capsular tear, posterior luxation of the nucleus, and greater vitreous herniation into the anterior chamber.

The key to surgical planning included a combination of factors, the most important was stabilizing the crystalline lens to enable phacoemulsification without further damaging the zonular support. The primary clear corneal surgical incision was made slightly inferotemporally (ie, opposite the area of greatest zonule weakness), and iris hooks and a CTS were used to stabilize the capsule and crystalline lens after compartmentalizing the anterior chamber and reducing the minor vitreous prolapse through the zonular dehiscence using Healon GV. Phacoemulsification was performed under low flow and power settings. The initial groove and subsequent phaco tip direction were toward the zonular dehiscence, avoiding further stretching of already damaged zonules.

Potential benefits of phacoemulsifying subluxed lenses over extracapsular cataract extraction largely relate to greater control of the anterior chamber and smaller incision size. There is also a decreased risk of iris prolapse, vitreous loss, retinal detachment, and expulsive hemorrhage. Had it been impossible to maintain the integrity of the capsule, we obtained patient consent to perform scleral suturing of an aniridic posterior chamber IOL, because the condition of the iris precluded functionally useful pupilloplasty.

DEVICES/INSTRUMENTATION
Capsular stabilizing devices. These tools facilitate safe phacoemulsification and IOL implantation by ensuring a stable capsule-iris complex. In the presence of lens subluxation, it may negate the need for more invasive surgery (eg, pars plana vitrectomy/lensectomy).1 The crucial requirement for inserting a capsular stabilization device is a complete continuous curvilinear capsulorrhexis.2 Surgical options in the presence of an intact capsular bag and zonule defects include capsular tension rings—either nonsutured (CTR) or sutured (mCTR)—and CTSs. Generally, a CTR is indicated in the presence of mild zonular instability and mCTR in extensive or progressive instability. Both are absolutely contraindicated if there are capsular tears. Here, a CTS is indicated, however, no published studies validate its use.2

Iris hooks. These devices for capsular stabilization have also been previously described.1,2 Some surgeons recommended tenting the capsule opposite the phacoemulsification incision, using four stab incisions slightly posterior to the sclerolimbal junction to prevent anterior tenting of the capsule. Others suggest combining iris hooks at the capsular edge with CTR placement between 3- and 6 o'clock of zonular dialysis and angling the hooks to lie in the plane of the anterior capsule.2 An article published in the Journal of Cataract and Refractive Surgery described a new flexible, 10–0-mm nylon, T-shaped capsular stabilization device. This device hooks around the capsulotomy margin, and the T-shaped end is passed around the anterior capsular flap to fit the equator curvature.1 We have found the use of iris hooks and a sutured CTS provides the greatest flexibility in cases such as the one presented.

Endocapsular prosthetic iris segments and aniridic IOLs. Because of the patient's fixed dilated pupil, one important consideration was whether to use a conventional 6-mm foldable IOL with iris segments or a one-piece PMMA aniridic (black iris surround) IOL. A retrospective study of six eyes with various causes of aniridia, including trauma, concluded that the black diaphragm aniridia IOLs are useful in such cases, providing subjective improvements in glare sensitivity and visual acuity.2 Intra- and postoperative complications, however, are not uncommon and are largely attributed to the technical difficulty of implanting these large diameter and relatively brittle IOLs (Morcher 67 and 67F; Morcher GmbH). Nonetheless, these IOLs may be the only option when there is no/insufficient capsular support and a pupilloplasty cannot produce a functional pupil diameter.

If the intact capsule with a continuous curvilinear capsulorrhexis may be preserved, endocapsular prosthetic iris segments are preferred. Burk et al4 reported that when endocapsular devices were implanted during cataract surgery, one single-fin device was used in eyes with sectoral iris loss up to 3 hours, two single-fin rings were used with sectoral iris loss of 3 to 6 hours, and when a full iris diaphragm is required, two multiple-fin ring types were inserted, rotated, and interdigitated—as in the case we report.

We prefer Morcher iris segments when there is extreme iris loss, because these devices may be inserted into the capsular bag through a 3.2-mm incision, whereas iris diaphragm IOLs must be inserted though an incision of 10 mm or longer.4 A larger incision increases the risk of vitreous prolapse, cystoid macular edema, induced astigmatism, inflammation, and secondary glaucoma.5 The black PMMA material used to make these iris segments is relatively fragile, and it should be handled with care. Placing two 50C multiple-fin devices plus an IOL into the capsular bag may result in overcrowding, making rotational alignment of the fins more difficult. Ultimately, the size of the fins and the diameter of the capsular bag determine the pupil diameter, and this should be considered when providing adequate reduction in pupil diameter, yet enabling posterior segment visualisation postoperatively.5

In conclusion, anterior segment reconstruction surgery often involves technically demanding cases. Fortunately, adjunctive devices are available to facilitate such challenging cataract surgeries. Although there is always a guarded visual prognosis in these cases, there is potential for good visual outcomes given careful preoperative planning and use of appropriate techniques.

Charles N.J. McGhee, PhD, FRCS, FRCOphth, is the Maurice Paykel Professor of Ophthalmology, Department of Ophthalmology, University of Auckland, in New Zealand. Professor McGhee states that he has no financial interest in the products or companies mentioned. He may be reached at +64 9 373 7599 ext. 86712; c.mcghee@auckland.ac.nz.

Divya Perumal, BOptom(Hons), BHB, is a research fellow in the Department of Ophthalmology, University of Auckland, in New Zealand. Dr. Perumal states that she has no financial interest in the products or companies mentioned. She may be reached at +64 9 373 7599.

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