Results of intraocular lens implantation with capsular tension ring in subluxated crystalline or cataractous lenses in children

Purpose: To evaluate the outcome of intraocular lens (IOL) implantation using capsular tension ring (CTR) in subluxated crystalline or cataractous lenses in children. Materials and Methods: We prospectively studied 18 eyes of 15 children with subluxation of crystalline or cataractous lenses between 90 0 up to 210 0 a ft er phacoemulsi ﬁ cation, CTR and IOL implantation. Each child was examined for IOL centration, zonular dehiscence and posterior capsular opaci ﬁ cation (PCO). Results: Age of the patient ranged between ﬁ ve to 15 years. Out of 18 eyes, seven had traumatic and 11 had spontaneous subluxation of crystalline or cataractous lens. Phacoemulsi ﬁ cation was successfully performed with CTR implantation in the capsular bag. Intraoperative zonular dialysis occurred in two eyes. Anterior vitrectomy was performed in six eyes to manage vitreous prolapse. IOL implanted was polymethyl methacrylate (PMMA) in eight eyes, hydrophobic acrylic in seven and hydrophilic acrylic in three. Follow-up ranged from 24 months to 72 months. Sixteen eyes had a best corrected visual acuity of 20/40 or be tt er. Nine eyes developed signi ﬁ cant PCO and were managed with Neodymium Y tt rium Aluminum Garnet (Nd:YAG) laser posterior capsulotomy. One eye with acrylic IOL in the capsular bag had IOL dislocation a ft er two years which was managed with vitrectomy and secondary trans-scleral ﬁ xation of IOL. Conclusions: Phacoaspiration with CTR implantation makes capsular bag IOL ﬁ xation possible in most of the eyes with subluxated crystalline or cataractous lenses. PCO still remains a challenge in children with successful phacoaspiration with CTR implantation

Management of subluxated crystalline lens in children is a challenge. Surgical procedures such as intracapsular cataract extraction, [1] limbal or pars plana lensectomy and anterior vitrectomy [2] and suturing of the capsule to the sclera or the haptics to the sulcus [3] have been reported with several complications. [4] Recent reports of management of subluxated cataract by phacoemulsifi cation with capsular tension ring (CTR) have shown encouraging results. [5,6] Hara et al, [7] introduced the ring called "Equator ring" in 1991 for the fi rst time for the maintenance of the completely circular contour of the capsular bag equator aft er cataract removal and to prevent posterior capsular opacification (PCO) by blocking the posterior movement of the lens epithelial cells at the equator. Nagamoto et al. [8] and Legler et al. [9] modifi ed this ring to an open ring with a slim loop. The standard CTR is an open-ended, fl exible horseshoe-shaped polymethyl methacrylate (PMMA) fi lament with two eyelets at their ends. CTR can be inserted into the capsular bag anytime aft er successful capsulorrhexis. Once positioned in the capsular bag, a CTR helps distribute the stress around the entire equatorial area. Because of this stress distribution, the likelihood of stretching or extension of zonular dialysis reduces significantly. [10] After surgery it maintains centration of intraocular lens (IOL) by keeping the capsular bag stretched. We evaluated the outcome of IOL implantation using CTR in subluxated clear or cataractous lenses in children.

Materials and Methods
We prospectively studied children recruited between January 2001 to December 2004, aged fi ve to 15 years with subluxation of crystalline or cataractous lens varying between 90 0 to 210 0 who underwent successful phacoemulsifi cation with CTR and IOL implantation. This was a nonrandomized observational study conducted with institutional review board clearance. These were consecutive cases where a successful CTR and IOL implantation was achieved. Parents were informed about the available options which included phacoaspiration with an IOL and CTR implantation, or pars plana lensectomy and anterior vitrectomy with or without trans-scleral fi xated IOL. Informed consent was obtained from parents before enrolling the child in the study aft er explaining the rationale of use of CTR, the nature of surgery, the associated risks, complications, and the expected visual outcome.
A complete ophthalmologic examination was done including best corrected visual acuity, applanation tonometry, slit-lamp biomicroscopy, presence or absence of vitreous in anterior chamber, and integrity of zonules. Degree of zonular dehiscence or separation was estimated using retroillumination in slit-lamp biomicroscope aft er full pupillary dilatation. Detailed dilated fundus evaluation was done using + 90D lens or indirect ophthalmoscope. IOL power was calculated using SRK-II formula. In case of uncooperative children biometry was done under general anesthesia. B-scan ultrasound was done for posterior segment evaluation if the fundus was not visible. If subluxation was suspected to be due to any heritable disease, internist opinion was sought regarding the diagnosis of the disease.
All surgical procedures were performed under general anesthesia. Mydriasis was achieved by using a combination of tropicamide 0.8% and phenylephrine 5% and cyclopentolate 1% three times at intervals of half an hour before surgery.
A valvular incision was made superiorly preferably in the axis of intact zonule using 3.0 mm disposable keratome in all cases and two side port incisions were made. High-viscosity visco-elastic sodium hyaluronate 1.4% (Healon GV ® , Advanced medical optics, Uppsala) was introduced into the anterior chamber through a side port incision. Continuous curvilinear capsulorrhexis (CCC) of 5 to 5.5 mm size was created with the help of a bent 26-gauge needle and Utt rata forceps. Flexible silicone iris hooks were used to stabilize the CCC margin in the area of the dehiscence in all cases. The stop on the hook was adjusted to hold the rhexis edge and stabilize the capsular bag. Subsequently a gentle multi-quadrant hydrodissection was performed. At this stage, the CTR (CTR-11, 13/11mm, Aurolab, Madurai, India) was introduced into the capsular bag with the help of Kelman-McPherson forceps and a second manipulating spatula to guide the device into the capsular bag. CTR of 13/11 mm size was used in all eyes. Subsequently, phacoemulsifi cation was performed with low vacuum and low aspiration and low bott le height. The remaining cortical matt er was removed by automated bimanual irrigation and aspiration. Vitreous in the anterior chamber at any stage of surgery was managed with a two-port anterior vitrectomy. The posterior capsule was left intact. In case of clear lens, the position of CTR was confi rmed by retracting the iris with Kuglen's hook immediately after the implantation of the CTR and in cataractous lenses, it was done aft er aspiration of cortical matt er. Posterior chamber (PC) IOL was implanted in the capsular bag placing the haptic in line with the area of zonular dehiscence. Depending upon the patient's aff ordability, all PMMA rigid IOL (Aurolab SQ3602, Madurai, Tamil Nadu, India), or hydrophobic acrylic IOL (Sensar Optiedge, AR40e, Advanced Medical Optic Santa Ana, California), or three-piece hydrophilic acrylic (RYCF, Care Group, Baroda India) was implanted. Residual visco-elastic was then removed. At the end of the procedure, centration and stability of the IOL was tested.
After surgery, patients were examined on slit-lamp biomicroscopy on Day 1, Day 7, Day 14, Day 28 and Day 90 and then six-monthly. At every visit the following parameters were noted: visual acuity, intraocular pressure, anterior chamber depth (symmetric /asymmetric), IOL centration, IOL tilt, capsular bag stability, zonular dehiscence and PCO. Patients' follow-up varied from 24 to 72 months.

Results
Of the 15 children included in the study, there were 10 male and fi ve female children. Age of the children ranged from fi ve to 15 years with a mean age of 9.20 ± 3.25 years. Out of 18 eyes, seven had traumatic subluxated cataractous lens and 11 eyes had spontaneously subluxated crystalline or cataractous lens. Out of seven traumatic cataracts fi ve were total cataract and two were posterior subcapsular cataract. The preoperative best corrected visual acuity (BCVA) ranged from HMCF (which is defi ned as perception of hand motion at two feet distance) to 20/80. The extent of dialysis ranged from 90 0 to 210 0 . Subluxation varied from 90 0 to 150 0 in nine eyes and more than 150 0 to 210 0 in nine eyes. In the area of zonular defect, zonules were totally absent in seven eyes and partially absent in fi ve eyes and stretched in six eyes.
Preoperatively, vitreous was present in the anterior chamber in three eyes with traumatic subluxation of lens. None of the eyes with spontaneous subluxation had vitreous disturbances preoperatively.
Phacoaspiration with limbal incision was performed with CCC in all cases. In all eyes CTR was implanted in the capsular bag and no major complication was noted during CTR implantation. Intraoperative extension of dialysis occurred in two eyes, one eye had traumatic cataract with vitreous in anterior chamber at presentation with 150 0 of subluxation, and the other eye had a subluxated cataractous lens with 160 0 of zonular dialysis. In both the eyes zonular dialysis extended to 180 0 intraoperatively. Capsular bag collapse did not occur in any eye with CTR. No eye had posterior capsular tear. In six eyes anterior vitrectomy was performed to manage vitreous prolapse in the anterior chamber. Out of these six eyes, three eyes had vitreous in anterior chamber preoperatively and in the remaining three eyes vitreous herniation occurred intraoperatively. In all eyes IOL was implanted in the capsular bag with good centration. IOL implanted was rigid PMMA in eight eyes and acrylic foldable in 10 eyes (hydrophobic in seven and hydrophilic in three eyes).
Postoperatively minimal corneal edema, mainly stromal and near section, occurred in fi ve eyes which resolved by fi rst postoperative week. Three eyes with traumatic cataract had more than 2+ cells and fl are at two weeks. In all cases anterior chamber infl ammation subsided with topical steroids. Two eyes developed raised IOP due to residual visco-elastic in the anterior chamber and responded well to anti-glaucoma medications.
All the IOLs were well centered on the fi rst postoperative day except for one case in which the IOL was decentered with edge of the IOL at the center of the pupil. On the third postoperative day, a second surgical procedure was done to recentre the IOL. One haptic of the IOL was fi xed to the sclera with 10-0 polypropylene monofi lament suture. All the IOLs at last follow-up remained well centered [Figs. 1,2] except in an eye where there were increase in the decentration with increasing capsular bag fi brosis [ Fig. 3].

Discussion
Trauma is the most common cause of subluxation of crystalline lens. Common causes of spontaneous subluxation include Marfan's syndrome, Weill-Marchesani syndrome, and homocystinuria. In the present study, seven eyes (seven children) had subluxation due to trauma and in 11 eyes subluxation was spontaneous [ Table 1]. Pars plana lensectomy with anterior vitrectomy had been employed for subluxated lens in children by various investigators with good visual outcome. [3,11] Although this procedure appears to give good visual outcomes, the patients remained aphakic postoperatively in all cases. The treatment of aphakia in children is a signifi cant challenge. Spectacle correction is not suitable for unilateral aphakia especially aft er surgery for traumatic subluxation due to anisokenia. Contact lens wear has its own drawbacks including keratitis, corneal neovascularization, noncompliance, frequent lens change and cost. Surgical methods of aphakic correction are implantation of anterior chamber IOL and trans-scleral fi xated IOL. Anterior chamber IOL fi xation is not a preferred modality in the pediatric age group due to several postoperative complications like corneal decompensation, glaucoma and retinal detachments. Recently published studies reported late dislocation of IOL due to breakage of polypropylene sutures in scleral fi xated posterior chamber IOL, especially in young patients. [12,13] Asadi et al, recently reported this disturbing late complication of trans-scleral fi xated IOL in children. In their series late IOL dislocation due to breakage of polypropylene sutures was noted aft er seven to 10 years in six out of 25 eyes (24%). [14] Problems of phacoaspiration in subluxated crystalline or cataractous lenses are extension of dialysis, vitreous loss, and cortical matt er aspiration from capsular bag, inability to implant posterior chamber IOL. Many of the recent studies on phacoemulsifi cation with CTR have shown encouraging results in the management of zonular dialysis in adult patients. [5,15,16] Implantation of CTR stabilizes the capsular bag and allows the surgeon to complete phacoemulsifi cation and IOL implantation. [5,15,16] In various studies, phacoemulsifi cation with CTR implantation was done in patients with subluxation ranging from 90 0 to over 200 0 . [5,15,16] In the present study, we had patients with subluxation of 90 0 to 210 0 .
Key points to successful CTR implantation are to use high-viscosity visco-elastic material, making the incision at a meridian with intact zonules, to avoid damaging zonular fi bers with the movement of the phacotip, perform slow-motion phacoemulsifi cation with a low fl ow rate, low vacuum, and low bott le height. In our study, high-viscosity visco-elastic sodium hyaluronate 1.4% (Healon GV) was used in all cases and incision was made in the area of intact zonules.
Some surgeons implant CTR aft er cortical aspiration and before IOL implantation [16] and others prefer to implant CTR before phacoemulsifi cation. [6] In our study, CTR was implanted just aft er the hydrodissection in all eyes. In an experimental study on cadaveric eyes Ahmed et al, [17] have shown that the ideal timing for CTR placement is aft er lens extraction. Jacob et al, [15] found intraoperative extension of the dialysis in 9.52% eyes and in one eye procedure was converted to a lensectomy with three-port pars plana vitrectomy for removal of dropped nuclear fragment. In our study, extension of dialysis occurred in two eyes. Another complication involved during CTR implantation is tear of capsulorrhexis margin. In a study by Praveen et al, [16] the authors aborted CTR implantation in two eyes due to anterior capsular tear. In the present study, we did not encounter a similar problem during CTR implantation.
Gimbel et al, [6] managed 14 eyes with subluxated cataractous lens with phacoemulsifi cation using CTR. The average age of the patients was 66 years, with a range of 45 to 88 years. Traumatic as well as spontaneous subluxation was included in this study. IOL was centered in all the 14 eyes aft er a followup period ranging from two to 11 months. Cionni et al, [5] also showed a similar result. In our study, one eye had decentration of IOL in the immediate postoperative period requiring second procedure to fi x one haptic to the sclera. IOL remained well centered in all eyes except one eye which showed increasing decentration of IOL.
In the present study, 16 out of 18 eyes (89%) had a fi nal visual acuity of 20/40 or bett er. One eye with traumatic cataract had postoperative BCVA of 20/400 because of macular scar and in another eye with idopathic subluxation, visual acuity did not improve beyond 20/60 because of amblyopia. Recently, Georgopoulos et al, [18] reported the long-term eff ect of CTR insertion in adult patients with large traumatic zonular dialysis aft er phacoemulsifi cation with PCIOL implantation. In their series of 17 eyes of 17 patients, zonular dialysis ranged from 80 0 to 160 0 . They did not encounter any intraoperative complication. Aft er a mean follow-up of 25.9 months (range 15 to 35 months) no IOL was found to be decentered, apart from one eye in which the PCIOL was dislocated due to postoperative trauma. Two eyes had poor postoperative visual acuity because of macular pathology.
Konradsen et al, [19] managed 37 eyes with ectopia lentis of non-traumatic etiology in children with a Cionni-modifi ed CTR (33 eyes) and conventional CTR (four eyes) and IOL with good long-term results. In their series, 26 eyes needed secondary surgery for visual axis opacifi cation. Two (5.4%) of their eyes needed secondary suturing for IOL dislocation. Vasavada et al, [20] reported intraoperative and postoperative performance of endocapsular ring implantation in pediatric eyes with subluxated lens. They included both spontaneous and traumatic subluxatation ranging from 180 0 to 250 0 . In all these cases they implanted Cionni CTR and single-piece AcrySof IOL in the capsular bag with good intraoperative performance. Visually signifi cant PCO had developed in 19 eyes (54.3%). Postoperative IOL decentration was observed in three eyes (8.5%) at a mean interval of 28+6.92 months. In our series, nine eyes had visually signifi cant PCO. In six eyes implanted IOL material was PMMA with round-edged optic and three eyes had a square-edged acrylic IOL. In all eyes with PCO, Nd:YAG laser posterior capsulotomy was done to regain optimal visual outcome. CTR may not off er signifi cant prevention of PCO in young children implanted with roundedged or square-edged IOLs. Increasing subluxation and subsequent dislocation of capsular bag with implanted IOL is a challenging situation which ultimately requires removal and vitrectomy and trans-scleral fi xation of PCIOL. We had an eye with 210 0 subluxation, implanted with acrylic hydrophilic IOL and CTR which dislocated with capsular bag aft er two years, probably due to increasing zonular dehiscence and capsular bag fi brosis. Pars plana vitrectomy with scleral fi xation of IOL was done in this case. It is technically diffi cult to remove CTR from the vitreous cavity as it may damage the retina. Ma et al, [21] described two techniques to remove the CTR from the vitreous cavity. In their fi rst case CTR was removed aft er cutt ing it into two pieces and in the second case CTR was removed in toto using CTR injector. Lang et al, [22] reported removal of posteriorly dislocated CTR intact through sclerotomy site. Surgical approach for dislocated capsular bag-IOL-ring complex depends on CTR position. If the capsular bag-IOL-ring complex is subluxated in the retropulpillary area, CTR-IOL complex can be sutured with sclera through anterior approach and when capsular bag-IOL-ring complex is dislocated completely in the vitreous cavity, pars plana vitrectomy, levitation of CTR-IOL complex with 20-gauge microforceps can be done. [23] In conclusion, advancement in the technique of phacoaspiraton along with CTR implantation makes capsular bag IOL fi xation possible in most of the eyes with subluxated crystalline or cataractous lenses in children. Use of CTR also helps in maintaining IOL centration, stabilization of capsular bag and good postoperative visual recovery. Thus phacoaspiraton with the help of CTR is a safe and predictable procedure in subluxated lens in children. However, elimination of PCO still remains a great challenge in children even aft er successful phacoaspiraton with CTR implantation. One important concern with implantation of CTR in subluxated lens is long-term follow-up to observe any change in the stability of capsular bag-zonular complex along with CTR and IOL for any chances of increase in dehiscence or dislocation into the vitreous cavity.