Laser IOL fragmentation
Low-energy femtosecond laser-assisted IOL fragmentation is less traumatic than manual methods
Natalia Anisimova MD
Low-energy femtosecond-laser transection of IOLs prior to explantation appears to provide a clean dissection of the lens allowing safe and easy removal for exchange, said Natalia Anisimova MD, S. Fyodorov Eye Microsurgery State Institution, Moscow, Russia.
“The clinical application of femtosecond laser-assisted IOL fragmentation is feasible in cases of hydrophobic IOL explantation,” Dr Anisimova told the 22nd ESCRS Winter Meeting in Belgrade, Serbia.
She noted that the need for IOL explantation is rare but seems to be increasing. Decentration, dislocation and incorrect lens power are the most common indications. Modern surgical techniques for IOL explantation include criss-cross lensotomy, removal of the optic only, bisection and trisection. However, these approaches carry a high risk of surgical trauma.
Dr Anisimova noted that there is also research that has shown that transection of an IOL for explantation can be achieved with a femtosecond laser set at an energy of 8.0µJ with a spot size of 3.0µm and a line separation size of 6µm. However, the high energy used with a small spot and separation size may produce excessive cavitation gas bubbles and the release of toxins.
To determine the optimum laser energy and laser spot positioning parameters, Dr Anisimova and her associates transected three hydrophobic acrylic IOLs with a femtosecond laser using laser energies of 1.0µJ to 10µJ and laser spot and layer separation size of 7.0µm for femtosecond laser IOL transection.
They found that with a laser energy of 1.0µJ they achieved a fragmentation score of “one”, meaning that though transection lines were apparent, the fragments could not be separated manually. However,
at energies from 2.0µJ to 10µJ they achieved a score of three, meaning clear transection lines and little force required for fragment dissection.
In addition, light microscopy showed that significant changes occurred on the surface of the IOLs proximal to the transection lines when they used energies of 8µJ to 10µJ, but not when they used energies of 6.0µJ.
In the first patient in whom they have tried the femtosecond laser-assisted technique using the 6.0µJ laser settings they were able to fragment and remove the lens without difficulty and endothelial cell counts did not change from one month postoperatively to six months postoperatively. In addition, uncorrected visual acuity improved from 20/2000 preoperatively to 20/20 at one month postoperatively, Dr Anisimova said.
Natalia Anisimova: firstname.lastname@example.org