The Facts on “Bladeless” Laser Assisted Cataract Surgery

Safety and Effectiveness of Laser-assisted Cataract Surgery and Standard Cataract Surgery (non-Laser assisted)  

“Bladeless” laser-assisted cataract surgery as it is commonly promoted is deceptive, as the cataract is not removed by the laser. Instead the cataract must be removed by the same Standard (non-laser) technique called Phacoemulsification.

There is a lot of misleading information being circulated in the media concerning the possible benefits associated with bladeless laser-assisted cataract surgery. It is important in your research that you thoroughly review the financial disclosures of the authors of these articles, publications and websites.

First and foremost, it is important that patients understand that the laser does not remove the cataract. The laser merely assists a surgeon in only several steps of a multi-step operation. Regardless that the femtosecond laser is used, the remaining more technically challenging aspects of the cataract procedure including; removing the cataract from the eye using ultrasound and aspiration, cleaning and polishing the capsular bag, insertion of the intra-ocular lens, removal of the viscoelastic, reconstitution of the globe, and instillation of intra-ocular medications must all be performed and completed by “hands on” techniques utilized in Standard (non-laser assisted) cataract surgery.

Laser “assisted” cataract surgery is almost identical to Standard cataract surgery, except instead of using a surgical micro-diamond blade, a femtosecond laser (FS) is used to fashion a primary 2.75mm incision through which the Phacoemulsification instrument tip is inserted into the eye. Regardless of how the small primary incision is fashioned, by diamond or FS laser, the Phaco instrument is required to remove the cataract. (The Phaco surgical instrument utilizes ultrasound to emulsify and liquefy the cataract thereby allowing the cataract to be removed through a small incision.) The FS laser is also used to “assist” with making an opening in the anterior lens capsule. Thirdly, the laser is used to “soften” the cataractous lens. In certain cases where astigmatism is treated the laser can be substituted for a micro-diamond blade to create limbal relaxing incisions (LRI).

In a standard non-laser cataract operation these three or four steps are typically completed in less than one minute total time and do not make up the more involved and technically challenging portion of a cataract operation.

The type of incision made by the FS laser is in fact not ideal for the intended purposes of cataract surgery. The FS laser does not really cut in true surgical fashion. Instead, micro burst, acoustic shock waves and photo vaporization to the cellular matrix of the tissue targeted by the laser create micro cavities (perforations) that have a similar effect as one would see on tear-off paper. Tissue treated in such a fashion requires the incision to be manually opened by blunt dissection to complete the effect. In some cases these laser incisions are incomplete and must be opened with a sharp blade.

Concerning the primary 2.75mm, the FS laser is not capable of making a sclera tunnel incision but only a clear cornea incision. The sclera is the white opaque outer covering of the eye. The FS laser cannot cut opaque tissue. When a FS laser incision is too peripheral, the scleral edge may be difficult to detect and causes an imperforate wound. Scleral tunnel incisions on the other hand can be performed using a manual blade.

There are potential problems with clear corneal incisions compared to sclera tunnel incisions.

Researchers at the Barnes Retina Institute in St. Louis saw a three-fold increased incidence of endophthalmitis following clear corneal incisions when compared to scleral tunnel incisions in a retrospective, case-control study (Cooper B, 2003;136:). Endophthalmitis is serious vision threatening infection inside of the eye. Unlike the clear cornea, the sclera is vascular which promotes faster healing and sealing. In addition a sclera tunneled incision is covered by two other protective layers of the eye, clear cornea incisions have none. Clear corneal incisions have been shown to leak several months out of surgery (Stratas, 2005;31(5):) (Chee, 2005;26(4–5):) (Wong RW1, 2010 Jun;30(6)) (Slettedal JK, 2005;83(1):1).

Clear corneal incisions also induce significantly more regular as well as irregular astigmatism than the scleral tunnel incision (Olsen T1, 1997 April).

Therefore there are no real advantages but rather disadvantages to using the FS laser to fashion the primary cataract incision as research shows.

Furthermore FS laser energy results in corneal stromal cell death and inflammatory cell influx (Fabricio Witzel de Medeiros, 2009 Oct). Eyes with laser-automated corneal incisions had greater endothelial cell damage and loss than those made with a blade (Robin G. Abell, November 2014, vol 40, Issue 11,).

There are however other types of eye surgery where utilization of a different type laser is more advantageous such as in Laser Vision Refractive Surgeries including; LAHayeSIK, Laser Assisted in-Situ Keratomileus (LASIK), Photo Refractive Keratotomy (PRK), and LaHayeSight Laser-Enhanced Premium Cataract Surgery. These procedures involve a different application and purposeful use of an excimer laser where the ultimate goal is to maximize clear vision and lessened dependency on glasses.

In laser-assisted cataract surgery a FS laser is used to “cut” an opening in the anterior capsule of the lens and “soften” the central nucleus of a cataract before it is removed using the standard phaco ultrasound instrument. The FS laser creates numerous small micro breaks in “cutting” the capsule. These micro breaks are numerous weak points along the edge of the capsule opening and contribute to a weaker capsule. A FS laser fashioned capsulorhexis is not as structurally sound as compared to the proven non-laser continuous linear capsulorhexis with smooth edges. A FS laser fashioned capsule opening must still be manually completed using micro forceps. The FS laser assisted capsulorhexis can result in an incomplete capsulotomy, capsulotomy tags, anterior radial capsular tears, and posterior capsular tears.

Proponents of laser-assisted cataract surgery publicize that the Phaco ultrasound time is reduced as a result of laser ‘softening”. In Standard (non-laser) cataract surgery the lens is both gently softened and delaminated by a proven technique of hydro-dissection and hydro-delineation. The bottom line is there is minimal to no reduction in ultrasound time when the laser is used. In addition, any potential effect is negated by the fact that the laser energy dissipated into the capsule and surrounding intra-ocular tissue may cause more harm than benefit. Examples of associated problems possibly resulting from dissipated laser energy include: vertical migration of acoustic air bubbles, an unstable pupil, significantly induced pupillary miosis, (Vasilios F. Diakonis, et al., February 2016 – ) an increase in capsule complications, an increase in corneal endothelial damage and cell loss (Zoltan Z. Nagy, January 2014), an increase in corneal haze, an abnormally increased intra-ocular pressure, and increase in cystoid macula edema(CME) (Shaun Y.P. Ewe, November 2015).

An additional setback associated with laser-assisted cataract operations is the need to abort the cataract operation because of loss docking vacuum on the eye during laser phase, or because of a small non-dilating pupil or hazy cornea. To be able to target and deliver the laser energy to the structures being treated the eye must be held securely (docked) using suction. In addition, the cornea must be perfectly clear for the laser to pass through with out damage and the pupil must be sufficiently dilated open as not to partially cover the lens capsule and lens nucleus. There are certain medications, medical conditions and eye disease that can result in a cloudy cornea and/or a poorly dilating pupil.

There are additional concerns associated with docking of the patient’s eye in laser-assisted cataract surgery. Docking in laser-assisted cataract surgery is similarly done in LASIK and is known to cause a significant rise in intraocular pressure, in the order of ≥14- 60 mm Hg. (Hernandez-Verdejo JL, 2007) (Chaurasia SS, 2010). This rise in intraocular pressure is likely to be more problematic in elderly cataract patients, with the risk of ischemic retinal and optic nerve injury. In particular, patients with advanced glaucoma may be at risk of ‘snuff-out’.

Another downside to laser-assisted substitution is that it adds considerable time to the entire operation, with patient on an operating table, potentially adding additional risk and complications. The laser-assisted stage of the procedure must first be performed under the femtosecond laser in a different location than the Standard second main stage of the operation. After completion of the laser-assisted phase the patient must be moved to another operating table in an environmentally controlled operating room. In the operating room the patient will be prepped and draped in a sterile manner. Under the operating microscope, the surgeon must then proceed with completion of the more technically challenging multi-steps of the cataract operation requiring Standard (non-laser) techniques.

A study involving over 4000 eyes proved an eight fold increase in intra-op complications associated with Laser-assisted cataract surgery as compared to Standard cataract surgery where the laser was not utilized (Robin G. Abell M. , January 2015).

A potential benefit of laser assisted cataract surgery could possibly be realized by less experienced low volume surgeons through the assistance provided. Creating a marketing niche with the lay person by “up selling” the cataract operation with the incorporation and use of high tech sounding “bladeless” laser-assisted wording may be another benefit.

Certainly more time and expense is currently associated with this emerging technology. As with all new types of technology that emerge, the full range of benefits and complications of laser-assisted cataract surgery is not yet known and many studies still need to be completed to realize the full outcome potential and downside risk.

Safe and effective cataract surgery requires a highly skilled surgeon and cataract care team that posses a vast amount of experience and knowledge. There are some things that can be replaced by technology however, as we know it today, the art of cataract surgery is not one of these.

We will keep our patients informed as new technologies become available. It is my opinion as well as the opinion of the overwhelming majority of cataract surgeons that laser assisted cataract surgery is not ready for prime time.

Comparisons of Safety and Effectiveness of Laser-assisted Cataract Surgery and Standard Cataract surgery (non-Laser assisted)

References

Cooper B, Holekamp NM, Bohigian G, et al. Case-control Study of Endophthalmitis After Cataract Surgery Comparing Scleral Tunnel and Clear Corneal Wounds. Am J Ophthalmol 2003;136:300-05

Stratas BA. Clear corneal paracentesis: a case of chronic wound leakage in a patient having bimanual phacoemulsification. J Cataract Refract Surg. 2005;31(5):1075

Chee SP. Clear corneal incision leakage after phacoemulsification-detection using povidone iodine 5% Int Ophthalmol. 2005;26(4–5):175–179.

Wong RW, Kokame GT, Mahmoud TH, Mieler WF, Tornambe PE, McDonald HR.

Complications associated with clear corneal cataract wounds during vitrectomy Retina. 2010 Jun;30(6):850-5.

Slettedal JK, Bragadóttir R. Total iris expulsion through a sutureless cataract incision due to vomiting. Acta Ophthalmol Scand. 2005;83(1):111–112

Olsen T, Dam-Johansen M, Bek T, Hjortdal JO.

Corneal versus scleral tunnel incision in cataract surgery: a randomized study J Cataract Refract Surg. 1997 Apr;23(3):337-41.

Nagy ZZ, Dunai A, Kránitz K, Takács AI, Sándor GL, Hécz R, Knorz MC. Evaluation of femtosecond laser-assisted and manual clear corneal incisions and their effect on surgically induced astigmatism and higher-order aberrations. J Refract Surg. 2014 Aug; 30(8):522-5. doi: 10.3928/1081597X-20140711-04

Fabricio Witzel de Medeiros, MD, Harmeet Kaur,Vandana Agrawal, Shyam S. Chaurasia, Jefferey Hammel, William J. Dupps, Jr, and Steven E. Wilson, MD¹ Effect of Femtosecond Laser Energy Level on Corneal Stromal Cell Death and Inflammation J Refract Surg. 2009 Oct; 25(10): 869–874.

Robin G. Abell, MB BS, Nathan M. Kerr, MBChB, Allister R. Howie, Mohd A.A. Mustaffa Kamal, MB BS, Penelope L. Allen, PhD, Brendan J. Vote, FRANZCO

Effect of femtosecond laser–assisted cataract surgery on the corneal endothelium

From Launceston Eye Institute (Kerr, Vote), Launceston, and Tasmanian Eye Institute (Abell, Howie, Mustaffa Kamal, Allen, Vote), Tasmania, Australia

Vasilios F. Diakonis, MD, PhD; Nilufer Yesilirmak, MD; Ibrahim O. Sayed-Ahmed, MD; Daniel P. Warren, MSc; George A. Kounis, PhD; Zachary Davis, MS; Florence Cabot, MD; Sonia H. Yoo, MD; Kendall E. Donaldson, MD, MS Effects of Femtosecond Laser-Assisted Cataract Pretreatment on Pupil Diameter: A Comparison Between Three Laser Platforms Journal of Refractive Surgery February 2016 – Volume 32 · Issue 2: 84-88

Zoltan Z. Nagy, MD, DS, Agnes I. Takacs, MD, Tamas Filkorn, MD, Kinga Kránitz, MD, Andrea Gyenes, MD,  Éva Juhász, MD, Gábor L. Sándor, MD, Illes Kovacs, MD, PhD, Tibor Juhász, MD, PhD, Stephen Slade, MD Complications of femtosecond laser–assisted cataract surgery. Journal of Cataract and RefraCTIVE Surgery January 2014 Volume 40, Issue 1, Pages 20–28

Shaun Y.P. Ewe, MBBS ,Carmen L. Oakley, MBBS ,Robin G. Abell, MBBS, Penelope L. Allen, PhD, Brendan J. Vote, Cystoid macular edema after femtosecond laser–assisted versus phacoemulsification cataract surgery Journal of Cataract and Refractive Surgery November 2015 Volume 41, Issue 11, Pages 2373–2378

Hernandez-Verdejo JL, Teus MA, Roman JM, Bolivar G. Porcine model to compare real-time intraocular pressure during LASIK with a mechanical microkeratome and femtosecond laser. Invest Ophthalmol Vis Sci 2007; 48: 68–72. 

Chaurasia SS, Luengo Gimeno F, Tan K, Yu S, Tan DT, Beuerman RW et al. In vivo real-time intraocular pressure variations during LASIK flap creation. Invest Ophthalmol Vis Sci 2010; 51: 4641–4645. 

Robin G.Abell, MB BS, Erica Darian-Smith, Jeffery B. Kan, MB BS, Penelope L. Allen, PhD, Shaun Y.P. Ewe, MB BS, Brendan J. Vote, Femtosecond laser -assisted cataract surgery versus standard phacoemulsification cataract surgery: Outcomes and safety in more than 4000 cases at a single center Franzco Journal of Cataract and Refractive Surgery- vol 41-52

Leon C. LaHaye, M.D.