Myopia, astigmatism and farsightedness are the most common refractive defects and now femtosecond laser surgery is considered a consolidated technique, in some ways ‘ancient’ because innovation in the ophthalmology field continues and today new solutions are also available. Techniques for correcting refractive defects are one of the main themes of the XII National Congress of the Italian Association of Ophthalmologists (Aimo), scheduled in Rome until Saturday 2 October.
The most used intervention in the world
Lasik assisted by femtosecond laser (FemtoLasik) is the oldest and most widespread technique worldwide for the surgery of refractive defects such as myopia, astigmatism and hyperopia that are corrected through a remodeling of the corneal surface. In the United States it is the main technique used in refractive surgery, as well as worldwide: out of 10 operations 8 are performed using this technique. “In Italy – he explained Luigi Mosca, head of the Uos of Cornea and Refractive Surgery of the Agostino Gemelli Irccs University Polyclinic Foundation of Rome and scientific referent of Aimo – many Prk are still done, a technique that consists only in the ablation of the surface, but in general we opt for a technique or for the other based on the various types and extent of the visual defect “.
The new femtosecond lasers
More recent is the Smile surgical technique assisted by femtosecond laser (FemtoSmile) indicated for the correction of medium and medium / high myopia which allows a saving of tissue and nerve fibers and respects the biomechanical stability of the cornea, as well as having a fast post-surgery recovery. Finally, the latest addition is the Smile-Xtra, a technique that combines the Smile with intraoperative crosslinking in order to strengthen the treated cornea and stabilize the results obtained over time.
When FemtoLasik is indicated
With FemtoLasik all types of defects can be corrected, especially hyperopia and astigmatism. Furthermore, this treatment can also be used in all post-operative defects, such as after corneal transplants, where there is a particularly difficult tissue to handle. “In this case the intervention is even safer – explained Mosca – because the ductility of the femtolaser allows you to manage the diameters, depths and geometries of the cuts. The only thing we cannot correct is presbyopia, because at the moment there is no effective technique to ‘go back in time’; however, to correct this defect there are multifocal intraocular lenses which are very valid “.
How it takes place
A FemtoLasik surgery takes on average about 10 minutes. “The first cut of the femtosecond laser lasts about ten seconds, after which there is the lifting of the superficial flap, the ablation with the excimer laser and the repositioning of the flap, so in total the intervention takes about ten minutes. “, Said Mosca, who then underlined how the pandemic has” slowed down the pace in the operating theaters “, even if” compared to the past we do in any case many more operations and much more easily, because we have fewer complications and fewer risks “.
The risks of the surgery
Can Lasik with femtolaser involve complications and risks? “Obviously they exist, but they are much lower in quantity and extent than those found in the past with the oscillating blade of the microkeratome”, replied Mosca reassuring patients: “All refractive surgery is frightening and understandable, but today it is precisely the safety of a totally computerized programming, together with a very high laser precision, which must make them quieter than in the past, when a coarser mechanical ‘blade’ was used ”. The laser, by dividing the molecular bonds, allows very precise cuts and less trauma on the eye itself. “So there is maximum security – added the expert. Thanks to the femtolaser we know perfectly the depth we reach and we are 100% certain of the corneal thickness we leave, with a clear reduction in the percentage of intra and post-operative complications. With the femtolaser the surgeon is safer than the tissue he manipulates and therefore the surgery itself ”.
The Indian Smile-Xtra technique
What does the new Smile-Xtra technique add and when is it indicated? “In refractive surgery – he explained to Congress Marco Fantozzi, head of the laser center San Rossore nursing home in Pisa – one of the most feared complications is corneal ectasia, that is, the wearing out of the cornea after an operation, because by removing parts of the cornea it could weaken. This is how an Indian surgeon, Sri Ganesh, came up with the idea in borderline corneas, those that are not very thick and where the risk of ectasia could be higher, to associate with the Smile technique, which preserves the hardest layer of the cornea, intraoperative crosslinking. Crosslinking of collagen has proven to be an effective way to strengthen and stabilize the cornea in keratoconus and ectasia after corneal refractive surgery ”. But what exactly is Smile-Xtra? “This is a low invasive para-surgical treatment – explained Fantozzi – which consists of a strengthening of the cornea obtained through the combined effect of a vitamin (riboflavin) and ultraviolet rays. This procedure has the purpose of compacting the corneal lamellae, thus hardening the cornea “.
The Italian study
Therefore, starting from the Indian surgeon’s idea, a multicentre study was conducted (which involved the San Rossore Nursing Home in Pisa, the La Sapienza University of Rome and the University of California San Diego) to verify the effectiveness of this treatment in borderline corneas, that is, in corneas in which the ectatic risk may be higher than in normal corneas. “From our cases – explained Fantozzi – it actually emerged that Smile-Xtra did not lead to corneal ectasias, proving to be a safe and effective procedure that can be offered to patients. Clearly, in order to give greater robustness to the results, further studies and a follow-up period of more than 24 months will be necessary. The premises are however promising, because in fact with this procedure a hardening of the cornea occurs, which should prevent the development of a posterior ectasia ”. To have more certain answers, a follow-up of at least seven years is necessary. “My first SMILE-Xtra dates back to 2016, so it will take another couple of years – added Fantozzi – The premises are, however, extremely positive: the association between SMILE surgery and intraoperative crosslinking clearly decreases the incidence of Post surgical ectasia “.
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