Femtosecond laser technology is a relatively new technology. Out of the four companies developing femtosecond cataract lasers only two are currently approved by the Food and Drug Administration (FDA), the LenSx and LensAR. What makes the femtosecond lasers for cataract surgery different that of the femtosecond laser technology used for LASIK is that they are approved for surgery inside the eye.
Current cataract procedures are performed manually with a blade. First a surgeon makes an incision in the periphery of the cornea. Then an anterior capsulotomy is performed by making an incision in the capsule that contains the lens. Then an ultrasonic probe is used to fragment the cataract. The fragmented lens is taken out and a man-made lens called an intraocular lens is placed in the capsule. During this process if the patient has astigmatism a diamond blade is used to perform limbal relaxing incisions to correct the refractive error in the eye. This procedure can last between 1 to 2 hours.
With the new femtosecond laser technology the cuts are performed with the laser. The fragmentation is also performed with the laser, reducing or eliminating the use of an ultrasonic probe. The laser can make the cuts self-sealing. These self-sealing incisions are cut at an angle so that when the cuts are closed the pieces lay over each other promoting quicker healing and less chance of infection.
One of the biggest advances with the femtosecond laser technology is the ability to map the eye. Both of these femtosecond lasers map the eye in different ways. The LenSx uses optical coherence tomography. Optical coherence tomography uses near infrared light. The light is used to penetrate the scattering medium usually biological tissue, in this case the eye, the changes in the light as it travels through the scattering medium creates a three dimensional map. The LensAR uses Scheimpflug imaging. Sheimpflug imaging is an imaging system based on the Scheimpflug principal where the measurement is taken from the side creating three different planes of the eye that intersects on one line, as opposed to the different levels of the lens being seen from above as one plane. With either mapping technique doctors can perform a more individually tailored surgical plan allowing for better post-surgical vision than with manual optical mapping.
The femtosecond laser is extended on an arm over the patient. The machine does the three dimensional mapping. Then the doctor uses the software to plot the course of the incisions. The lasers make the cuts and then fragment the cataract. The fragmented cataract is removed and the intraocular lens inserted in the capsule. The procedure done with the laser takes approximately 15 to 20 minutes. The fact that these surgeries are shorter reduces the risks of things like involuntary patient movement which can change even the most perfect cut into a different shape or an incorrect depth. Cuts of an incorrect shape or depth can affect the capsular coverage of the intraocular lens and thereby affect the outcome of the entire procedure; a patient’s recovered visual ability may not be all it could have been.
The laser makes tighter incisions than manual cuts. The femtosecond laser for cataract surgery allows doctors and patients and to enjoy consistent precise results surgery after surgery patient after patient.
These femtosecond lasers can perform these surgeries with amazing precision. The laser paired with three dimensional mapping allow for more control and more reliable results. Doctors and patients will across the board push for this technology to be more widely available.