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Femtosecond laser offers new possibilities for cataract surgery
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Femtosecond laser technology has had a great impact on the field of ophthalmology since its introduction in 2001. Its clinical application has been gradually extended from LASIK flap creation to lamellar corneal surgery, and now it is reaching out to cataract surgery, which is by far the most common ophthalmological procedure performed worldwide.
There are currently four companies actively developing femtosecond laser technology for cataract surgery, and each system has unique features. Generally speaking, femtosecond laser technology is able to perform a few steps of cataract surgery, including corneal wound construction (main and paracentesis wounds), capsulorrhexis, nuclear fragmentation and astigmatic relaxing cuts. The rest of the surgery, such as removal of nuclear and cortical matter, has to be taken care of in the usual way of a phacoemulsification procedure. Therefore, it may be more appropriate to coin the term “femtosecond laser-assisted cataract surgery” in order to give a clearer picture in the current stage of development. Other features of femtosecond laser technology include combined cataract and refractive surgery (Bausch + Lomb/Technolas), real-time optical coherence tomography that may allow visualization of the anterior chamber (Alcon/LenSx and OptiMedica) and a liquid optic interface that is pressure-free to the eyeball (LensAR and OptiMedica).
Theoretical advantages
There are a number of theoretical advantages of femtosecond laser-assisted cataract surgery, including the creation of a well-centered and precisely sized capsulorrhexis, which allows perfect centration of IOL implantation and will in turn lead to a better performance of a premiem IOL. Secondly, the risk of anterior capsule tear, which may extend to the posterior capsule and cause further complications, such as dropped nucleus, is reduced. Moreover, femtosecond laser-assisted cataract surgery often results in a well-constructed uniplanar, biplanar, triplanar or multiplanar self-sealing corneal wound, which may reduce the chance of postoperative endophthalmitis.
Femtosecond laser-assisted cataract surgery normally requires less phaco energy, which can reduce the potential damage to the corneal endothelium and the incidence of cystoid macular edema. Finally, a more precise depth control of astigmatic relaxing cuts is another potential advantage of femtosecond laser-assisted cataract surgery. This can reduce the chance of wound perforation and, at the same time, ensure efficacy.
More study needed
Despite the potential advantages, robust clinical evidence from large-scale comparative studies confirming these advantages is warranted. Moreover, it has become clear that the learning curve of femtosecond laser-assisted cataract surgery could be pretty steep even for experienced phaco surgeons. Bali and colleagues recently reported a number of complications arising from the first 200 femtosecond laser cataract surgeries in his group practice. Such complications include anterior capsule tags (10.5%), anterior radial tear (4%), posterior capsule rupture (3.5%), dropped nucleus (2%) and pupil constriction after femtosecond laser procedure, which will require topical 10% phenylephrine.
With the well-known problems intrinsic to femtosecond laser technology, such as high costs, limited availability, possibility of suction loss when docking and increased surgical time, the use of femtosecond laser in cataract surgery is still limited to only a small number of centers worldwide.
The current phacoemulsification procedure has a high safety profile, and most surgeons are confident and comfortable with performing the procedure in a short period of operating time. Whether the merits of femtosecond laser technology can significantly outweigh its limitations and hence cause a paradigm shift, as phaco did when it replaced manual extracapsular cataract extraction to become the norm, remains to be seen in the years to come.
References:
Bali SJ, Hodge C, Lawless M, Roberts TV, Sutton G. Early experience with the femtosecond laser for cataract surgery [published online ahead of print Feb. 21, 2012]. Ophthalmology. doi:10.1016/j.ophtha.2011.12.025.
Kim P, Sutton GL, Rootman DS. Applications of the femtosecond laser in corneal refractive surgery. Curr Opin Ophthalmol. 2011;22(4):238-244.
Rao SK, Jhanji V, Fan AH. Femtosecond laser: Is it the way forward for cataract surgery? Asia Pac J Ophthalmol. 2012:1(1):3-4.
Ratkay-Traub I, Juhasz T, Horvath C, et al. Ultra-short pulse (femtosecond) laser surgery: initial use in LASIK flap creation. Ophthalmol Clin North Am. 2001;14(2):347-355.
For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at Hong Kong Eye Hospital, The Chinese University of Hong Kong, 3/F, 14K Argyle Street, Kowloon, Hong Kong, SAR, China; +011-852-2762-3157; fax: +011-852-2715-9490; email: dennislam8@cuhk.edu.hk.
Disclosure: Dr. Fan and Dr. Lam have no relevant financial disclosures.