FEMTO CATARACT

There is currently no peer-reviewed evidence supporting the idea that femtosecond-assisted cataract surgery is safer and more effective than traditional phacoemulsification techniques in routine cataract cases, George H H Beiko BM, BCh, FRCSC reminded delegates attending the 2013 Congress of the Society of European Ophthalmology.

“We know that the femtosecond lasers can be used to create corneal incisions, capsulotomies and to liquefy and fragment the lens. However, if you look carefully at all these indications there is currently no peer-reviewed data to support the case for doing femtosecond laser cataract surgery,” said Dr Beiko.

Dr Beiko, assistant clinical professor of ophthalmology at McMaster University, Ontario, Canada, noted that femtosecond technology is not the first laser technology that has been used over the years to remove cataracts.

“We have seen various systems and devices such as Daniel Eichenbaum’s YAG laser, Jack Dodick’s NG-YAG laser and Michael Colbert’s erbium YAG laser, all of which have fallen by the wayside and have not stood the test of time for routine cataract cases,” said Dr Beiko.

Some of the femtosecond laser systems currently on the market are FDA approved, but none have actually undergone controlled FDA-approved trials, said Dr Beiko. “All have been approved through a side system which allows them to come into use without any FDA-approved trials,” he said.

In economic terms, Dr Beiko said it was very hard to make a compelling case for femtosecond laser use in cataract surgery.

“The cost to our hospital (in Canada) is about $650 for a routine cataract case. That is the direct and indirect cost, including nurses, the hospital and the capital cost. For femtosecond cataract surgery, we add in the cost of the laser, which is typically about $500,000, a maintenance contract which is about $40,000 a year and then there is the click fee of about $400 dollars per case. Depending on the volume of the practice, this works out to a charge between $1,500 and $2,500 dollars per case, which is a very significant difference indeed,” he said.

While it has been suggested that femtosecond cataract surgery results in better self-sealing incisions, more accurate reduction of astigmatism, better quality of vision and faster visual recovery, scrutiny of the scientific literature shows little evidence to back up these claims, said Dr Beiko.

Taking the example of astigmatism, Dr Beiko said laser correction is possible for the 35 per cent to 40 per cent of patients with astigmatism between 0.75 D to 2.0 D. “We know that using toric lenses and limbal relaxing incisions is comparable in that range. So you are effectively spending $1,500 to $2,500 dollars for a technology to do what a toric lens can already do at a significantly reduced cost,” he said.

Dr Beiko noted that studies by Nagy et al. have shown that the femtosecond laser is more reproducible and accurate than manual methods for creating capsulotomies. “However, Burkhard Dick has shown that using a data-injection system (DIS, Carl Zeiss Meditec) to project a reference ring onto the anterior capsule can accomplish a similar level of accuracy for the capsulotomy as with a femtosecond laser,” he said.

A recent study by J A Davison of 468 patients showed that an incomplete overlap of the optic in one or more quadrants versus a complete overlap resulted in only 0.12 D more myopia, said Dr Beiko.

“In other words, if you do not have a perfect capsulotomy it is about one-eighth of a dioptre of difference compared to having a perfect capsulotomy. So having a perfect capsulotomy does not seem to impact that much on the end result,” he said.

The idea that femtosecond cataract surgery results in much less energy being delivered into the eye should also be placed in its proper context, said Dr Beiko.

“We have seen studies by Dr Nagy and others showing that they can reduce the amount of phaco energy into the eye by around 50 per cent by using femtosecond technology. However, I presented a study back in 2002 showing how to use the Akahoshi pre-chopper to reduce phaco energy by as much as 55.79 per cent in my cases. And the chopper is much cheaper than the laser and there is no click fee to use it,” he added.

On the subject of anterior and posterior capsular tears, Dr Beiko said that their incidence seemed to be related more to the experience of the surgeon than the type of technology being used.

“One study shows that four per cent of the first 200 cases had anterior capsular tears with femtosecond laser and just 0.3 per cent in the subsequent 1,300 cases. With traditional phaco, another study showed the rate of anterior capsular tears in the first 300 cases was five per cent and less than one per cent thereafter. The same also holds true for posterior capsular tears, with experienced phacoemulsification surgeons reporting tear rates of less than one per cent which is in the same range as femtosecond technology,” he said.