| Dermot McGrath in Munich
A MODIFIED capsular tension ring (M-CTR) provides a safe, reproducible and effective means of implanting posterior chamber intraocular lenses in cataract patients with profound zonular weakness, according to a Canadian ophthalmologist. Presenting the results of a study at the XXI Congress of the ESCRS, Iqbal Ike Ahmed MD, FRCSC, said that he and his co-researchers had been impressed with the performance of the M-CTR device in dealing with high-risk cataract patients. "Phacoemulsification and endocapsular placement of a posterior chamber IOL can be safely and effectively performed with the aid of the Cionni M-CTR to provide suture fixation and stability of the capsular zonular complex. This small-incision, closed system approach provides improved refractive results with minimal complications," said Dr Ahmed. In a study involving 68 patients, Dr Ahmed said that the M-CTR was used during phacoemulsification and implantation to effectively provide excellent lens centration and stability. "We are very pleased with the preliminary results. Uncorrected and best corrected visual acuity stabilised or improved in 97% of cases and postoperative complications overall were minor and controlled," noted Dr Ahmed. The double-eyelet M-CTR was utilised in 10 cases while single eyelet devices were used for the remainder. Preoperative diagnosis included lens subluxation due to Marfan's Syndrome (22 cases), trauma (19 cases), ectopia lentis (1 case), pseudoexfoliation (6 cases) and other (12 cases) After an average follow-up of 12.4 months, complications included elevated intraocular pressure in (6 cases), mild IOL tilt (5 cases), pigment dispersion (2 cases), mild iritis (5 cases), and cystoid macular oedema (4 cases). The IOL was well centred at last follow-up in all cases. Laser capsulotomy for significant PCO was performed in six (9%) cases. There were no cases of suture breakage or extrusion.Although two eyes lost some lines of BCVA after surgery due to chronic cystoid macular oedema, Dr Ahmed said that both patients had individual risk factors for this condition. There were no cases of significant IOL tilt. In terms of surgical technique, topical anaesthesia was used in 38 patients (56%), retrobulbar in nine (13%) and general in 21 (31%).
Dr Ahmed emphasised that initial results indicated that the Cionni modified CTR is a significant advance in the management of patients with severely dislocated cataracts. "Although these are high-risk eyes, the M-CTR provides for an extremely safe and effective approach with results similar to routine phacoemulsification in medium-term follow-up," he concluded. In a related presentation in Munich , Dr Ahmed also shared the first preliminary clinical results of his own specific twist on the Cionni modified CTR: the Capsular Tension Segment (Morcher, Stuttgart , Germany ). Dr Ahmed said that the segment, or CTS, provides increased versatility for early or late placement within the capsular bag, and was useful in cataract cases with weak zonular support that couldn't be helped with a Cionni M-CTR. Dr Ahmed described the CTS as a partial ring with a 5 mm radius of curvature and holes for iris retractor or suture fixation and said that double segment implantation could be used for generalised and progressive zonular weakness.Unlike the full Cionni ring, which is most easily placed after phacoemulsification, a CTS can be inserted after the anterior capsulotomy but before phaco without inducing significant capsular bag torque and zonular stress. The device can then be supported with an iris retractor during phacoemulsification without the inherent risks of anterior capsular tear or dislodgement which may occur with capsular retractors. The CTS can also be used in the setting of an anterior capsular tear or posterior capsular rent, which are usually contraindications for the use of a tension ring. In clinical tests, visual outcomes and complications from a prospective consecutive series of 14 patients implanted with a semicircular PMMA ring segment for significant zonular dialysis were documented. The CTS was successfully sutured into position in all 14 patients, despite a posterior capsule rent in one patient, and an anterior capsule tear in another. Visual acuity improved or stabilised in all patients. There were no cases of IOL decentration at mean follow-up of 10 months. "The capsular tension segment is a versatile zonular support device that can be safely implanted intraoperatively and provides postoperative support for in-the-bag IOL implantation. It can be implanted with minimal capsular or zonular stress," added Dr Ahmed. The Cionni M-CTR allows for scleral fixation in cases of significant zonular dialysis and provides long-term centration of in-the-bag foldable intraocular lenses.Previous techniques of suture placement require placement of the primary incision along the axis of zonular weakness or enlarging and/or distorting the primary incision to attain pr oper positioning. They also use blind passes of the needle under the iris to approximate the ciliary sulcus.The modified CTR, however, incorporates an additional fixation eyelet through which a suture may be passed and secured to the sclera, enabling the surgeon to provide optimal in-the-bag posterior chamber IOL placement. Iqbal Ike Ahmed MD, FRCSC
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Adjunctive intraoperative procedures included pars plana vitrectomy in 10 patients (15%), limbal vitrectomy in eight (12%), iris/pupillary repair in eight (12%), trabeculectomy in seven (10%), and tube-shunt implantation in two (3%). In all cases the endocapsular M-CTR was implanted after removal of the crystalline lens by phacoemulsification through a temporal clear corneal incision. For intraoperative support during phacoemulsification, iris/capsular retractors were placed at the capsulorhexis edge. After placement of the M-CTR a foldable IOL was implanted into the capsular bag Dr Ahmed said that original CTR had been designed to buttress areas of zonular weakness and recruit tension from existing zonules to support the loose capsular bag. "Although this was suitable in mild cases of zonular instability, the CTR was unable to re-centre and stabilise a severely subluxated lens or capsular bag complex. This led to sub-optimal visual results and increased postoperative complications," he said. He noted that Dr Cionni's innovation with the CTR enabled scleral suture fixation of the endocapsular device to provide adequate IOL centration stability within the physiological confines of the capsular bag."This enables the surgeon to use a small-incision, closed system approach to lens extraction and posterior chamber IOL placement, thus minimising surgical trauma, vitreous prolapse and suboptimal location of IOL implantation," he said. 