Optimised Femtosecond Laser System

02 Februari 2013    379 views

The Catalys™ Precision Laser system (OptiMedica), a next generation femtosecond laser system optimised for cataract surgery, performs anterior capsulotomies with greater precision than that achieved manually by experienced surgeons and all but eliminates the need for ultrasound during lens emulsification and removal, said h Burkhard Dick MD, PhD, Ruhr University Eye Clinic, Bochum, Germany. "The improvements in precision made possible by the Catalys system are truly remarkable and represent a significant advancement in the practice of modern cataract surgery," Prof Dick said at the 16th EsCRs Winter Meeting. 

He noted that he first began working with the Catalys system in December of last year and since that time has used it in over 140 cataract procedures. To illustrate the potential benefits that the system can provide to cataract surgeons and their patients, Prof Dick presented the results achieved in 57 eyes of patients who underwent femtosecond laser-assisted cataract surgery and compared them with those he achieved in 52 eyes of patients who underwent standard phacoemulsification with manually performed capsulorhexes. 

The patients in both the femtosecond laserassisted and standard phacoemulsification groups had cataracts ranging from LOCs grade one to grade four in density. Those in the femtosecond group had a slightly higher LOCs grade with mean nuclear density 3.4. in all eyes in the femtosecond-laser treated group Prof Dick used the same femtosecond laser settings in terms of laser fragmentation pattern, pulse energy, grid spacing and spot separation. He also used the stellaris phacoemulsification system (Bausch + Lomb) with a coaxial technique in all eyes. 

Accurate and safe
Prof Dick noted that examination of the removed capsule tissue showed that capsulotomies created with the laser deviated from their target diameter by a mean of only 29.0 microns. That compared to a mean deviation from target diameter of 339.0 microns in the manually created capsulorhexes. in addition, the mean circularity of the capsulotomies, where 1.0 represents a perfect circle, was 0.936 in the femtosecond group, compared to 0.774 in the manual group. Moreover, eyes undergoing cataract surgery with the Catalys system required only a minimal amount of effective phaco time in even the hardest cataracts. The mean effective phaco time was only 0.16 seconds in 57 eyes that underwent phaco-fragmentation with the femtosecond laser, compared to 4.07 seconds in 52 eyes that underwent standard phacoemulsification, representing a 96 per cent reduction in phaco time. 

Furthermore, the amount of effective phaco time required in eyes with LOCs grade ii, iii, iV cataracts was only 0.02 seconds, 0.16 seconds, and 0.25 respectively in eyes treated with femtosecond laser. That compared to phaco time requirements of 1.29 seconds, 1.96 seconds, and 3.32 seconds in the conventional phacoemulsification group, respectively, for the same grades of cataract. "The exposure to ultrasound has been minimised or eliminated, with 74 per cent of the cases requiring 0.25 seconds or less and 31 cases using zero seconds. The Catalys technology i believe may enable cataract removal via aspiration through a 1.2mm incision. if consistently demonstrated, this result will create need for new iOLs that will fit through these incisions," he added. 

In regards to safety, Prof Dick said that there were no capsular tears or vitreous loss or other iatrogenic complications in any eyes. Eyes treated with Catalys had corneas that were extremely clear from the immediate postoperative onward. Moreover, the conjunctiva remained unaltered, even in patients receiving anticoagulant therapy due to minimal IOP rise induced by Liquid Optics™ suction ring. in the femtosecond group,the iOL positioning was perfect with all types of IOLs used including toric and accommodative iOLs, he added. 

Catalys: key technologies
Prof Dick noted that the Catalys Precision Laser system combines an ultra-rapid femtosecond laser, integrated optical coherence tomography imaging, and specific pattern scanning technology. Furthermore, the Liquid Optics™ interface fills in corneal surface irregularities with liquid and thereby optimises the optical path for visualisation and the delivery of laser energy to the patient's eye, he said. "When you apply the suction ring to the eye, the intraocular pressure rise is low. The mean IOP increase we measured was 10 mmhg. And because it is a fluid-filled interface, the cornea is not applanated," he noted. 

The Catalys system provides visualisation of the ocular surfaces, from the corneal surface into the vitreous, using an integrated infrared camera and three-dimensional spectral domain OCT imaging technology, Prof Dick said. The system also has built in algorithms that detect and map in 3D relevant ocular surfaces to customise treatment plan with a well-defined safety zone. Once the surgeon has confirmed the treatment plan on the OCT images, the treatment proceeds with the capsulotomy and phaco-fragmentation. The capsulotomy takes a few seconds to complete and phacofragmentation time is dependent on a number of factors such as pattern chosen, grid spacing and pupil dilation. The entire procedure time (from suction on to suction off at completion of cuts) had mean of two and a half minutes, the maximum time was three and a half minutes and the fastest was one and a half minutes. 

Summarising his experience in his first 140 cataract cases with the Catalys system, Prof Dick said that it improved the precision of sizing the capsulotomy compared with manual technique. The system also demonstrated a significant improvement in precision of capsulotomy size and shape. The use of the laser also resulted in a considerable reduction in ultrasound energy use during phacoemulsification. "The next goal will be to eliminate ultrasound phaco totally by modifying the instruments and the vacuum settings and laser settings. i'm very confident that femtosecond cataract surgery will become an integral part of our surgical options," he concluded.