SMOOTH MICRO CUTS

Using a femtosecond laser to create smooth micro cuts inside the crystalline lens may provide a quick, effective and safe means of treating the loss of accommodation in presbyopic patients.

“We have been trying to restore the elasticity of the natural lens of the eye by generating sliding planes in the crystalline lens using a femtosecond laser (ROWIAK GmbH). These micro cuts reduce the inner friction inside the crystalline lens and help to restore its flexibility. The advantage of this procedure is that we do not have to open the eye and therefore we do not need a sterile operating room and can perform this as an in-office procedure,” Holger Lubatschowski PhD told the XXXI ESCRS Congress in Amsterdam.

There is a strong rationale for using ultrafast laser pulses to try to restore accommodation, Prof Lubatschowski said.

“Presbyopia leads to loss of near focusing ability and we know that the ciliary muscle continues to contract in presbyopic eyes. Secondly the lens capsule stays elastic with age and we now know that lens stiffness is the single key factor that limits the accommodative amplitude at any age and ultimately leads to a complete age-related loss of accommodation,” he said.

Ex vivo studies initially demonstrated proof of concept of the lentotomy procedure, showing that the use of appropriately selected cutting parameters could generate significantly enhanced flexibility in the human lens. In terms of safety, subsequent studies in animal eyes showed no evidence of cataract induction arising from the creation of sliding planes in the crystalline lens, said Prof Lubatschowski.

He noted that a pilot clinical trial in humans has commenced at two German sites: the University Eye Hospital of Rostock and Augenklinik am Neumarkt in Cologne. This phase I safety study will be carried out on 30 cataract eyes in patients aged between 50 to 65 years. The study eye will receive femtosecond lentotomy with no capsulorhexis, followed one week later by conventional cataract surgery, while the fellow eye will be treated with conventional cataract surgery alone.

Prof Lubatschowski said that a lot of the initial research focused on determining the optimal laser settings for generating smooth cuts with minimal creation of gas bubbles that might result in unwanted light scattering.

“That is why we use an ultrafast femtosecond laser with a shorter pulse duration than other commercially available devices. Using the right parameters, the lesions generated can be confined and localised to a range of just a few microns. We need to use the correct laser energy and pulse spacing in order to obtain the desired outcome,” he said.

Using a docking procedure similar to femtosecond cataract procedures, the entire lentotomy procedure takes just 30 to 60 seconds depending on the size of the sliding planes being generated.

“We remarked in these few first eyes that the laser lesions are clearing off quite rapidly in a matter of hours to a few days. The distance vision seems to be unchanged, which means that with the right pattern we do not induce aberrations,” he said.

Holger Lubatschowski: h.lubatschowski@rowiak.de