Analysis of data from surgeons in Australia who have used femtosecond laser for selected cataract and refractive lens exchange patients indicates that the technique is as safe and effective as standard cataract surgery. Whether it proves to be a superior technique remains to be proven.
In the April edition of mivision, the imminent arrival of the femtosecond laser for cataract surgery and refractive lens exchange was announced. At that point all potential advantages were putative and the call was made for those who acquired the technology to report on their experiences. In this article I will accept that challenge.
The Vision Eye Institute Chatswood installed an Alcon LenSx femtosecond laser in May 2011. It was the first femtosecond laser for cataract surgery in the southern hemisphere and is recognised currently as the highest volume femtosecond cataract practice in the world. A number of surgeons have now used the technology including Dr. Lawless, Dr. Jacobs, Dr. Ng, Dr. Roberts, Dr. Hughes, Dr. Chan, Dr. Chen and myself.
Data is being collected as part of Human Research Ethics Committee approved clinical trials, two scientific papers have been submitted to peer reviewed journals and multiple abstracts have been submitted to Australian and International Scientific Meetings.The aim being to disseminate our early experience and results to help flatten the learning curve of those who plan to embrace the technology.
The advent of any new technology is exciting but fraught with potential hazards. While early experience from surgeons such as Dr. Zoltan Nagy suggested the technology was safe and effective, the published literature includes only relatively small series.
…all cases have been completed successfully with visual outcomes typical of my standard small incision cataract surgery…
Learning Curve Analysis
We have analysed the learning curve of the initial 200 cases of six surgeons.The results indicated that there was indeed a learning curve and that the learning curve was different depending on whether the surgeon was a refractive surgeon with prior femtosecond laser experience or was using this type of technology for the first time. This difference was highly statistically significant (p<0.001). Importantly with time, however, these differences have become less apparent.
The femtosecond laser works by delivering high energy in a very small space of time. It can create a capsularhexis, fragment the crystalline lens and create the corneal wounds for the phacoemulsification piece and side ports.
At the time of writing this article, I have completed 50 cases with the femtosecond laser. I have found it to be an enjoyable journey and all cases have been completed successfully with visual outcomes typical of my standard small incision cataract surgery. I have had no major problems; capsular ruptures, corneal oedema, inflammatory or infective issues and my effective phacoemulsification energy is reduced. We have not yet analysed the refractive data and I suspect large numbers will be required to demonstrate any putative advantage of a more predictable effective lens position and consequent tighter refractive outcomes.
There have, of course, been challenges. One of the critical steps is achieving suction and fixation of the eye with a cone like device similar to that used in femtosecond LASIK. There was initially a difference in the number of docking attempts between those of us who had used a femtosecond previously and those who hadn’t. Increased experience meant that this technical challenge became easier for all surgeons.
The precision of the rexis was impressive. I found a 5mm rexis was ideal for toric, multifocal and standard intraocular lenses with adequate capsular cover and access. Surgeon choice meant that sizes ranged from 4.8 to 5.5mm. I was somewhat surprised with the initial low rate of complete capsularhexis and care was required to ensure no residual “bridges” were left. I had two anterior capsular tears, which I “rounded out” prior to commencing hydrodissection. Both surgeries were completed without an issue, however failure to attend carefully to the capsular edge could result in radial tears and posterior capsular involvement. Progressive changes to the energy settings and profiles have resulted in a higher percentage of completely “free capsules”. The corneal wounds were also very precise.
The lens fragmentation was also impressive but worked best on cataracts with a moderate nuclear sclerosis. I would advise against the use of this technology for very advanced cataracts until the technology has further matured. The OCT imaging and laser delivery was very precise and there were no cases of laser impacting the posterior capsule.
One surgeon in our group had two cases of capsular block syndrome, which resulted in nuclear displacement requiring vitectomy and a second procedure to remove the lens. In both cases the visual outcomes were good but these cases highlight an important scenario that can occur with this technology. The femtosecond laser for cataract surgery increases the risk of capsular block syndrome in a small percentage of the population. Whether this is because of gas production, heating and adhesion of the cortex to the anterior capsule or a more watertight anterior chamber is unclear. An adjustment needs to be made to any surgical technique that does not involve initial anterior chamber decompression and careful hydrodissection. If I detect a retrolenticular gas pocket I use an Akahoshi nuclear divider to release it prior to hydrodissection.
I have enjoyed using, and look forward to continuing to use, the femtosecond laser for my selected cataract and refractive lens exchange patients. It appears to me as safe and as effective as standard cataract surgery in my hands. Whether it proves to be a superior technique in terms of safety and refractive predictability remains to be proven. We are committed to collecting the data necessary to answer these questions and sharing our experience with our colleagues.
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Professor Gerard Sutton is the inaugural Sydney Medical School Foundation Professor of Corneal and Refractive Surgery at Sydney University.