22 Sep 2015
LZH and partners apply femtosecond sources and OCT to expand the range of laser-assisted procedures.
That growth has taken place as procedures such as cataract surgery and laser-assisted in situ keratomileusis (LASIK) have embraced the use of ultra-fast sources as a means to assist surgeons and improve clinical outcomes.
But some other established ophthalmic procedures, as well as some specific eye diseases, have not to date been as automatically well-suited to the adoption of femtosecond tools.
A new collaborative project between Laser Zentrum Hanover (LZH) and four research partners aims to expand the range of opportunities available for laser-assisted ophthalmology, by examining how femtosecond sources in combination with optical coherence tomography and adaptive optics can be combined in new and beneficial strategies.
Christened IKARUS - from "innovative cataract, presbyopia and retinal treatment using ultrashort laser pulses" - the project involves LZH alongside optics designers QIOPTIQ Photonics, laser-scanner specialists ARGES, and the Laserforum Köln for clinical consulting. ROWIAK are acting as system manufacturers.
Seeing more deeply
One target is presbyopia, the unwelcome progressive inability to focus the lens of the eye which comes naturally to almost the entire population with age.
Using lasers to directly treat presbyopia by cutting gently into the lens has been a potential route to easing the symptoms for some time; the laser can create deliberate slip planes within the lens, helping to restore some of the lost flexibility. But this involves cutting much more deeply into the fragile tissues of the eye than in a relatively surface-level procedure such as LASIK.
The key to success is to image deep enough into the eye, effectively visualizing the tissues to be cut. For this, the Image Guided Laser Surgery Group of the Biomedical Optics Department at LZH has adapted an OCT imaging unit and equipped it with bespoke software, enabling it to image both the cutting of the eye and the laser beam delivery during the operation.
As a result the IKARUS team has successfully made the necessary cuts without damaging the fragile front or rear parts of the surrounding lens capsule, a promising step towards countering the presbyopia symptoms without complications. Further clinical studies are now in progress to examine this approach further.
Another focus of interest for IKARUS involves reaching much further into the eyeball, all the way to the retina. Vitreomacular adhesion is a condition in which the vitreous gel in the rear chamber of the eye adheres too strongly to the retina, creating an unhealthy pull on the sensitive cells and potentially causing ocular damage.
Treating these retinal adhesions has typically involved surgically draining the vitreous humour from the eye; but IKARUS is developing an alternative laser-based procedure.
The technique involves integrating adaptive optics into the femtosecond laser operation, allowing it to cut close to the retina with increased precision. First results from treatment of the retinas of pigs' eyes have established that the system can cut membranes located only a few hundred microns away from the retina, leaving the retina itself with no noticeable damage.