The clinical data, which has since been published in peer-reviewed journals, showed early promise for the precision of the technology and a learning curve that seems to diminish quickly with experience.1,2 At the time, Professor Sutton said femtosecond laser for selected cataract patients appeared as safe as manual surgery. However, he believed, more clinical data was needed to establish its safety profile and quantify that refractive outcomes are more predictable than manual cataract surgery.
Medical writer, Jenny Saunders, recently went along to “Cutting Edge”, the Australian Cataract and Refractive Surgery (AUSCRS) meeting in Queenstown, New Zealand to find out what’s being said about LenSx 15 months on.
Femtosecond lasers have now been used successfully in refractive surgery for many years. In laser refractive cataract surgery the laser’s ultra-short pulse length is integrated with high-resolution anterior segment imaging that allows key steps of the procedure, including corneal incisions, the anterior capsulotomy and lens fragmentation to be planned, automated and then performed by the surgeon with computer-guided precision.
As more femtosecond lasers are installed, and surgeons progressively use LCS on a greater proportion of patients, the volume of data is increasing and we are now starting to demonstrate the clinical benefits of this technology. At the Australian Cataract and Refractive Surgery (AUSCRS) meeting held in August this year, Professor Sutton presented a comparison of the first 200 patients with the next 1300 cases in the VEI series, which demonstrated a significant reduction in intra-operative complications, compared to their initial 200 eyes (Table 1)3. These findings are to be published (in press) by Roberts et al.4
|
Complications
|
Initial group (n=200) |
Second group (n=1300) |
P Value |
| Pupillary constriction | 9.5% | 1.23% | <0.001 |
| Anterior capsule tags | 10.5% | 1.62% | <0.001 |
| Anterior radial tears | 4% | 0.31% | <0.001 |
| Posterior capsule tears | 3.5% | 0.31% | <0.001 |
| Posterior lens dislocation | 2% | 0% | <0.001 |
Table 1. Intraoperative complications for LCS comparing an initial group (incorporating the learning curve of 8 surgeons) and the following 1,300 eyes. Presented at AUSCRS, Queenstown, New Zealand, 20123 and to be published (in press) by Roberts et al4.
Professor Sutton said this second patient group (n=1,300) is the largest LCS series reported to date and demonstrates that both anterior and posterior capsule tears occur with a frequency of 0.31 per cent of eyes,3 which is lower than that reported for manual cataract surgery.5,6
For comparison:
- Robert Osher’s group, based on a series of more than 2,600 eyes, reported a manual anterior capsular tear rate of 0.79 per cent.5
- Howard Gimbel et al. (n=18740 eyes) reported a manual posterior capsule tear rate of 0.45 per cent.6
When the VEI results for LCS are compared to manual results reported in a large population of surgeons the differences are more apparent. In a review of 602,533 manual cataract procedures performed during 2002 to 2009, at 52 centres on the National Swedish Register, Lundström et al reported a posterior capsule tear rate of 2.09 per cent7 – approximately a seven fold reduction for LCS. Reducing posterior capsule tears is a key goal of the surgeon, as even in the best hands, 63 per cent of posterior tears require vitrectomy.6 The second patient group reported by VEI showed no difference in complication rates between surgeons with and without prior experience with a refractive femtosecond laser (p=0.860).3
Although manual cataract surgery is one of the safest procedures performed worldwide, these preliminary results suggest surgeons need to consider the benefits of LCS.
Slit lamp image of LCS at day 1. Courtesy of Vision Eye Institute, Chatswood.
Predictability
Early LCS studies reported by Kranitz et al (Dr. Nagy’s group) demonstrated significantly greater predictability with capsule overlap and IOL centration in eyes that had LCS versus manual techniques (p<0.05).8 LCS eyes have less tilt and coma aberrations, and better corrected distance visual acuity at one year, compared to eyes where the capsulorhexis is created manually (p=0.006).9,10
“This represents early evidence that the refractive results could be better, but at this point there are no Randomised Controlled Trials showing clinical superiority,” said Professor Sutton, who has ethics approval for such a trial at VEI.
“For refractive lens exchange patients, the advantages are likely to be more obvious. Small improvements are important for these patients. They are often low hyperopes, typically younger and have better vision to start with. You are more likely to hit target, if the IOL stays where you intend to put it and this refractive predictability is more important when you are implanting aspheric and multifocal IOLs,” he said.
Image shows capsulotomy immediately after cataract removal. Courtesy of Vision Eye Institute Chatswood. Capsulorhexes created with LCS are more consistent in shape, size and centration, and show a better capsule overlap of the IOL compared to manual techniques.8,9,10,11
Associate Professor Colin Chan et al.12 reported at the same meeting on 90 eyes undergoing LCS with ReSTOR (+3.0D) that were statistically matched and compared to 46 eyes receiving ReSTOR after manual phacoemulsification. The mean spherical equivalent for the two groups were comparable, but more eyes in the LCS group (75 per cent) achieved an uncorrected distance visual acuity (UDVA) >20/25 than in the manual group (60 per cent, p=0.024).12
“Premium IOLs demand premium care and that includes premium surgery. There is less give in the point-spread function of a multifocal lens, so centration is more important. In our Restor data, uncorrected vision was better in the LenSx group than the manual group, but as there was no refractive difference between groups, the LenSx result may be due to better IOL centration,” said Associate Professor Chan.
The Future
Professor Sutton says he now uses the LenSx laser system for all cataract cases. He believes the refractive results with LCS will only get better as surgeons refine their technique, share their results and manufacturers improve the technology and algorithms.
Currently there are four commercial LCS lasers (Alcon LenSx, OptiMedica, Technolas and LensAR), however the majority of the published data is on the LenSx laser system, with more than 200 LenSx installations and 50,000 procedures performed worldwide.13 There are 11 LenSx laser systems installed in Australia and New Zealand.13
The LenSx laser system has just received approval for corneal flap creation expanding the laser’s capabilities beyond cataract surgery to give surgeon’s more choice in corneal refractive surgery.13 Current LenSx customers will be able to upgrade their existing platform to perform the corneal flap procedure.
Alcon has developed a smaller patient interface, that not only improves patient docking in small eyes, but reduces the transient rise in intraocular pressure that is observed in routine use.13 The LenSx OCT imaging resolution has been doubled to provide a clearer image for planning the incisions.13 Recent upgrades to the LenSx software increase the automation for pre-positioning of parameters, but also gives more options for the surgeon who wants to individualise treatments.13
Femtosecond laser use for cataract surgery, in particular the LenSx laser system, is now supported by clinical data which demonstrates that its innovative technical features are reflected in clinical benefits that should compel manual-based surgeons and their patients to adopt this technology. Last year, at the AUSCRS meeting in Canberra, surgeons spoke about whether to do laser cataract surgery. This year, they spoke about how.
Jenny Saunders is an optometrist and medical writer who consults for the ophthalmic and medical device industries. She was sponsored by Alcon Australia to write this article for mivision.
LenSx is a registered trademark of Alcon Laboratories. Professor Gerard Sutton and Associate Professor Colin Chan are from the Vision Eye Institute, Chatswood. Dr Michael Lawless from the Vision Eye Institute, Chatswood, is a Consultant for Alcon LenSx, USA.
Alcon Laboratories (Australia) Pty Ltd, 10/25 Frenchs Forest Road East, Frenchs Forest NSW 2086.
References:
1. Bali SJ, Hodge C, Lawless M, Roberts TV, Sutton G. Early experience with the femtosecond laser for cataract surgery. Ophthalmol 2012;119(5):891–899.
2. Roberts TV, Lawless M, Chan CC, Jacobs J, Ng D, Bali S, Hodge C, Sutton G. Femtosecond laser cataract surgery: technology and clinical practice. Clin Experiment Ophthalmol. 2012; Accepted Article, doi: 10.1111/j.1442-9071.2012.02851.
3. Sutton G, Lawless M, Roberts T, Bali S, Hodge C. Clinical outcomes: lessons from the first 1500 eyes undergoing laser cataract surgery [abstract]. In: Proceedings of the 16th Annual Meeting of the Australian Cataract and Refractive Surgery; 2012 August 9-12; Queenstown, New Zealand: p34.
4. Roberts TV, Lawless M, Bali SJ, Hodge C, Sutton G. Surgical outcomes and safety of femtosecond laser cataract surgery: A prospective study of 1500 consecutive cases. (in press).
5. Marques FF, Marques DM, Osher RH, Osher JM. Fate of anterior capsule tears during cataract surgery. J Cataract Refract Surg 2006 Oct;32(10):1638-1642.
6. Gimbel HV, Sun R, Ferensowicz M, Anderson Penno E, Kamal A. Intraoperative management of posterior capsule tears in phacoemulsification and intraocular lens implantation. Ophthalmology 2001;108:2186 –2192.
7. Lundström M, Behndig A, Kugelberg M, Montan P, Stenevi U, Thorburn W.
Decreasing rate of capsule complications in cataract surgery: eight-year study of incidence, risk factors, and data validity by the Swedish National Cataract Register. J Cataract Refract Surg 2011 Oct;37(10):1762-1767. Epub 2011 Aug 6.
8. Kránitz K, Takacs A, Miháltz K, Kovács I, Knorz M, Nagy ZZ. Femtosecond laser capsulotomy and manual continuous curvilinear capsulorrhexis parameters and their effects on intraocular lens centration. J Refract Surg 2011:27(8):558-563.
9. Miháltz K, Knorz M, Alio J, Takacs A, Kránitz K, Kovács I, Nagy ZZ. Internal aberrations and optical quality after femtosecond laser anterior capsulotomy in cataract surgery. J Refract Surg 2011;27(10):711-716.
10. Kránitz K, Miháltz K, Sandor GL, Takacs A, Knorz M, Nagy ZZ. Intraocular lens tilt and decentration measured by Scheimpflug camera following manual or femtosecond laser-created continuous circular capsulotomy. J Refract Surg 2012;28(4):259-263.
11. Lawless M, Hodge C. Femtosecond laser cataract surgery: An experience from Australia. Asia Pac J Ophthalmol 2012;1:5-10.
12. Chan C, Lawless M, Sutton G, Roberts T, Hodge C. RESTOR and LENSX: The initial experience [abstract]. In: Proceedings of the 16th Annual Meeting of the Australian Cataract and Refractive Surgery; 2012 August 9-12; Queenstown, New Zealand: p31.
13. Alcon data on file, 2012.
