Divided opinions on use of femtosecond lasers in cataract surgery

Leading cataract surgeons agree that the femtosecond laser improves the precision of multiple steps of cataract surgery. However, the impact of its use on clinical outcomes and its place in clinical practice are more controversial, stressed two noted surgeons in a debate held during the XXIX Congress of the ESCRS.

According to Zoltan Nagy MD, the increased control afforded by femtosecond laser-assisted cataract surgery translates into increased efficacy and safety and will make the laser especially useful for improving outcomes with premium IOLs. He acknowledged that many questions need to be answered, and the new technology is probably not ready for widespread adoption. Nonetheless, patients are already asking for the laser, and he predicted market demand would drive its uptake.

Responding that he prefers manual surgery, Takayuki Akahoshi MD, said that he believes that some of the benefits of the laser are being overstated and that its limitations, particularly its cost, cannot be overlooked.

Dr Nagy, professor of ophthalmology, Semmelweiss University, Budapest, has been involved in the development and clinical evaluation of the LenSx femtosecond laser (Alcon LenSx). He reviewed data from studies evaluating the LenSx laser for optimising lens fragmentation and improving the reproducibility of incision creation and capsulotomy, along with evidence showing how its use translates into measurable improvements in clinical outcomes.

Results from one comparative study showed use of the laser for pre-phaco lens fragmentation reduced ultrasound use for completing nucleus removal. In eyes with grade 2-4 cataracts, fragmentation with the femtosecond laser decreased average phaco power by 51 per cent and effective phaco time by 43 per cent compared with standard phacoemulsification.

Studies have also shown that corneal incisions created with the computer-programmed femtosecond laser are more architecturally reproducible and better self-sealing with exact wound edge apposition compared with those made manually with a blade. In a study evaluating integrity of two-plane incisions, stromal hydration was needed to close 85 per cent of manually created incisions but in none of the eyes that had femtosecond laser incisions.

'Increased consistency in surgical and arcuate incisions will improve our understanding of incision outcomes, make surgically-induced astigmatism more predictable, and make astigmatic correction more accurate,' Dr Nagy said.

The ability of the laser to create capsulotomies that are more regularly shaped, accurately sized, and centred has also been shown in a clinical trial where eyes undergoing manual capsulorhexis were the control. This advantage of the laser was shown to translate into increased refractive outcome accuracy in a study where the achieved SE was within 0.25 of intended in 77 per cent of eyes that had a femtosecond laser capsulotomy compared with 54 per cent of eyes having a manual capsulotomy.

'Refractive outcome is more predictable after laser capsulotomy because final resting position of the lens is determined by capsule diameter, shape, and centration. With its advantages for more reproducible incision creation, enabling creation of a free-floating capsulotomy, and reducing manual manoeuvres, phaco time and energy to remove lens material, the femtosecond laser will facilitate and improve microincision cataract surgery,' Dr Nagy said.

An alternate view

Providing his perspective, Dr Akahoshi, director of ophthalmology, Mitsui Memorial Hospital, Tokyo, Japan, noted that while the laser performs each of its surgical steps efficiently, overall procedural efficiency is decreased because of the requirements for docking, alignment, imaging, planning, and transporting patients between the laser and operating rooms. The extra time can be a significant drawback for busy surgeons.

'I perform 50 to 55 cases daily, six days a week. With an average surgical time under four minutes, I can manage 10 cases an hour moving between two operating theatres. Using the femtosecond laser would increase my case time 4- to 5-fold and lead to a long waiting list for my cataract surgery patients,' he said.

Dr Akahoshi acknowledged that capsulotomies created with the femtosecond laser are more accurately sized and regularly shaped than a manual capsulorhexis, and that the laser may be beneficial for novice cataract surgeons. However, these younger practitioners will also be unable to afford the laser, and considering posterior capsule opacification development, there should be no difference between procedures performed with a femtosecond laser or a manual technique as long as the anterior capsular rim overlaps the optic (Figure 1).

Addressing femtosecond laser incision creation, Dr Akahoshi characterised the idea of using it to make limbal relaxing incisions (LRIs) as 'ridiculous'.

'LRI is an old-fashioned procedure with poor predictability and that may induce irregular astigmatism. Excimer laser correction or toric IOLs are better alternatives for treating corneal astigmatism,' Dr Akahoshi said.

He agreed that the femtosecond laser has benefits for pre-chopping dense cataracts and minimising ultrasound use in these more difficult cases. However, to avoid posterior capsule rupture, current laser lens fragmentation algorithms leave a significant posterior plate of lens, and so manual pre-chopping may still be needed.

'Using an appropriate mechanical nucleofractis technique and instruments, surgeons can successfully manage cataracts of all grades and reduce ultrasound energy consumption and total phaco time. The key is to not only crack the nucleus, but to achieve complete division of the nuclear fragments,' Dr Akahoshi said.

Finally, he pointed out there are situations where the femtosecond laser cannot be used. For example, capsulorhexis creation and pre-chopping are not possible in eyes with a small pupil, and there may be problems with docking in small, deep-set eyes, which are common in the Asian population.

'What the femtosecond laser can do is just make incisions, capsulorhexis and pre-chop which can be done much faster and more easily by hand. Even if I may get a free laser machine, I will not use it, because it's more time consuming and less efficient. Maybe after 20 years later when I'm old enough to have difficulties in manual surgery, I may consider to use,' Dr Akahoshi said.