Effectively comanaging femtosecond laser-assisted cataract surgery

April 3, 2014

The use of a femtosecond laser during cataract surgery is now an option for your patients, and you need to be comfortable answering patient questions and co-managing this procedure.

The use of a femtosecond laser during cataract surgery is now an option for your patients, and you need to be comfortable answering patient questions and co-managing this procedure. Your surgeon may refer to the procedure using several acronymns (Table 1). You may be more likely to see a femto-assisted phacoemulsification procedure than femto-assisted LASIK these days, despite the fact that femto procedures started with LASIK. Current femtosecond laser systems use neodymium: glass 1053 nm wavelength light to create a tiny, 3-micrometer spot with an accuracy of 3 microns.1 While slower excimer and YAG lasers create collateral damage of surrounding tissues when fired, the femtosecond laser’s ultrashort pulse (10-15 seconds) does not damage surrounding tissues. The pulse results in a plasma formation and, secondarily, cavitation bubbles which separate tissue in a process called “photodisuruption.”

Figure 1Originally, femtosecond lasers used photodisruption in LASIK to create a flap. This was expanded to include channels for corneal segments, astigmatic keratectomy (AK), or limbal incisions for astigmatism correction, and incisions for corneal transplants. This technology has now been applied to cataract surgery. How is the technology used in modern cataract surgery? The femtosecond laser is utilized in several steps prior to phacoemulsification. The capsulorhexis, lens fragmentation, clear corneal incision, paracentesis, and arcuate incisions are all created using the femtosecond laser. Once the laser treatment is complete, phacoemulsification is performed.

Currently, 5 systems are available for femto-assisted surgery.2 These include the Catalys (Optimedica), LenSx (Alcon Laboratories, Inc), Victus (Bausch + Lomb), LensAR (Lensar, Inc.), and the Victus (Technolas). FDA-approved procedures are listed for each system in Table 2.

Figure 2Most systems create the capsulorhexis, fragment the lens to facilitate removal, and then create corneal incisions. The laser requires a patient interface to properly dock the eye (Figure 1). Once the eye is properly docked, imaging allows treatment parameters to be viewed, and confirmed by the surgeon (Figure 2).

 

Capsulorhexis

The femtosecond laser is able to precisely create the capsulorhexis while reducing the risks of tearing the capsule and preventing decentration (Figure 3).  Typically a diameter of 5.0 mm is used, but this is easily modified by the surgeon based on pupil diameter and chosen intraocular lens (IOL). Several studies have found laser capsulotomies to be more precise in reproducibility and size than manual capsulotomy.2 Improved refractive outcomes with less lens tilt and decentration have also been reported.3 Psuedoexfoliation, subluxation, and hypermature cataracts are associated with complications during capsulorhexis in cataract surgery, and this technology may be particularly beneficial in these cases.

Figure 3AThe capsulotomy is particularly important for effective lens position and refractive outcomes. When calculating IOL power, historical formulas represent the effective lens position with a single number. We know that the IOL is not a thin lens. We cannot accurately predict where the IOL will sit based upon the axial length and keratometry, and lenses of different powers will not be located in the same plane due to the difference in shape. This introduces error and affects the refractive outcome. The size of the capsulotomy has a direct effect on the anterior chamber depth.4 Precise control of the capsulorhexis is thought to increase the likelihood of the desired refractive outcome.

 

Figure 3B
 

 

Lens fragmentation

Figure 4The natural lens is broken into sections, with patterns varying between the currently available systems and surgeon preference (Figure 4). This may or may not include lens softening, which reduces or may eliminate the need for phacoemulsification.

Reduced phacoemulsication energy and time have been reported with femtosecond laser use.5,6 This has found to be most beneficial in complex surgical cases, such as hypermature cataracts. Those with weak zonular fibers may also benefit from laser fragmentation. 

Those with Fuch’s7 or recurrent iritis may also benefit from the lower energy and less phaco time required with the femtosecond procedure. Anterior chamber inflammation should be less given the reduction in energy and phaco time, as well. A recent study compared anterior chamber flare after femtosecond laser-assisted cataract surgery and standard cataract surgery using phacoemulsion.8 The study found significantly less aqueous flare 1 day post-operatively, as well reduced increase in outer zone macular thickness measured by optical coherence tomography in the laser group. Researchers also evaluated the possibility of not using phacoemulsion during surgery when using femtosecond laser. They reported that effective phacoemulsification time was reduced 28.6% within the femtosecond group. Overall, a 96.2% reduction in estimated phaco time was found between standard cataract surgery and the optimized femtosecond pretreatment group.9

Corneal incisions

Figure 5The clear corneal incision (CCI) is created as specified by the surgeon as to depth, length, and location, as is the paracentesis (Figure 5). The CCI reportedly has minimal effect on corneal topography.10

Relaxing, limbal, or arcuate incisions are placed to minimize corneal astigmatism.  These refractive incisions may be opened at the time of surgery or later as needed according to the corneal astigmatism found post-operatively. They have been found to be stable and not to increase higher order aberrations post-operatively.11

Complications

Patients whose intraocular pressure (IOP) needs to remain controlled, such as those with glaucoma or retinal vascular problems, may not be suitable candidates for the femtosecond procedure due to the pressure increase required. Applanation and elevation of IOP are required for imaging and creation of the incisions. Severe corneal scarring may prohibit the procedure as well as it may obscure views.12

Subconjunctival hemorrhages may occur, but anticoagulants are not typically discontinued prior to surgery. Lower pressure elevations with updated systems lessen this occurrence. IOP increase is lower than those seen with LASIK procedures, only 10-20 mm Hg. The vision is not affected during the laser’s application like that seen with LASIK so the patient is able to fixate during procedure, and the patient’s level of discomfort is less than with LASIK. 12

Orbits must be able to accommodate the suction ring for docking. Patients who are not able to lie flat may not be candidates because a flat table is required for applanation.  

Small pupils are challenging to capsulorhexis creation. Typically a 5-mm capsulorhexis is created, but it may be smaller to accommodate smaller pupils. Both applanation and laser energy application may result in miosis intraoperatively. Corneal procedures cause miosis, possibly due to increased prostaglandins after femtosecond laser treatment.13

Suction loss is rare but may occur. Patients with nystagmus may not be suitable candidates. If suction is lost during capsulorhexis creation, standard phacoemulsication procedures will be used to complete the procedure. Bubbles induced by laser application make imaging after suction loss difficult, but the laser may be used after phacoemulsification for corneal incisions. Incomplete capsulotomy is rare but may occur. Radial tears may be difficult to see, and these adhesions increase the risk for problems with the capsulotomy. 

 

Logistics

The location of the laser is typically in one of 2 places: in the operating room or in a separate procedure room. The laser procedure does not require a sterile field because incisions are not opened until the patient is taken to the operating room. Five to 30 minutes may lapse between the femtosecond procedure and phacoemulsification. Pupillary miosis occurs after the femtosecond procedure, so it is recommended the phacoemulsification occur within 40 minutes.2

Procedural billing, not surprisingly, immediately prompted discussion. The American Academy of Ophthalmology and the American Society of Cataract and Refractive Surgery issued “Guidelines for Billing Medicare Beneficiaries When Using the Femtosecond Laser” in 2012. The 2 societies adopted the position that Medicare beneficiaries could not be billed for a medically necessary cataract surgery, regardless of the type of IOL that was implanted. The same guidelines acknowledged that patients could be billed for use of the femtosecond laser when a refractive procedure was performed. Because the femtosecond laser performs components of standard cataract surgery, some argued it should not be billed. Others felt femto-assisted surgery provided a refractive benefit and should be considered refractive.

On November 16, 2012, CMS posted “Laser-Assisted Cataract Surgery and CMS Rulings 05-01 and 1536-R.”14 In this document, CMS provided additional guidance. The document states: “Medicare coverage and payment for cataract surgery is the same irrespective whether the surgery is performed using conventional surgical techniques or [a] bladeless computer-controlled laser. Under either method, Medicare will cover and pay for the cataract removal and insertion of the conventional intraocular lens.”

The document further stated: “If the bladeless, computer-controlled laser cataract surgery includes implantation of a PC-IOL or AC-IOL, only charges for those non-covered services specified above may be charged to the beneficiary. These charges could possibly include charges for additional services, such as imaging, necessary to implant a PC-IOL or an AC-IOL, but that are not performed when a conventional IOL is implanted.” 

Thus, 2 components of the femtosecond-laser assisted cataract surgery may be billable: refractive incisions and the imaging required to perform the procedure.As a result, these services may be charged to the patient. 

Most surgeons bundle the laser procedure fees with premium lenses: toric or presbyopia correcting IOLs. These premium procedures require additional documentation with signatures. Surgeons typically require payment prior to the procedure. Payment plans, such as Care Credit, may be offered by the surgeon to enable patients to make payments over time.

Femtosecond laser-assisted cataract surgery in the optometric office

When evaluating patients for cataract surgery in your office, it is best to mention the availability of this technology to all patients. Never assume a patient can’t afford it or may not want it-you risk them undergoing standard cataract surgery and returning angry that they were not informed. Pre-operative care of other ocular health concerns prior to surgery, such as glaucoma, does not differ from standard cataract surgery. Control of ocular surface disease (OSD) in those pursuing femto-assisted procedures needs to be addressed to ensure quick healing and stable vision after surgery.

Post-operatively, topical medications are typically the same as standard phaco procedures. The patients will be more likely to comment (dare I say complain) of residual refractive errors, and management of OSD should be aggressive to maintain a happy patient. I typically treat femtosecond cataract surgery patients like I would a LASIK patient because the expectations for a strong refractive result are similar.ODT

References

1. Kullman G, Pineda R II. Alternative applications of the femtosecond laser in ophthalmology. Semin Ophthalmol. 2010 Sep-Nov;25(5-6):256–64.

2. Reddy KP, Kandulla J, Auffarth GU. Effectiveness and safety of femtosecond laser-assisted lens fragmentation and anterior capsulotomy versus the manual technique in cataract surgery. J Cataract Refract Surg. 2013 Sep;39(9):1297-306.

3. Miháltz K, Knorz MC, Alió JL, Takács AI, et al. Internal aberrations and optical quality after femtosecond laser anterior capsulotomy in cataract surgery. J Refract Surg. 2011 Oct;27(10):711-6.

4. Cekiç O, Batman C. The relationship between capsulorhexis size and anterior chamber depth relation. Ophthalmic Surg Lasers. 1999 Mar;30(3):185-90.

5. Abell RG, Kerr NM, Vote BJ. Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology. 2013 May;120(5):942-8.

6. Mayer WJ, Klaproth OK, Hengerer FH, Kohnen T. Impact of crystalline lens opacification on effective phacoemulsification time in femtosecond laser-assisted cataract surgery. Am J Ophthalmol. 2014 Feb;157(2):426-432.

7. Conrad-Hengerer I, Al Juburi M, Schultz T, Hengerer FH, et al. Corneal endothelial cell loss and corneal thickness in conventional compared with femtosecond laser-assisted cataract surgery: three-month follow-up. J Cataract Refract Surg. 2013 Sep;39(9):1307-13.

8. Abell RG, Allen PL, Vote BJ. Anterior chamber flare after femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2013 Sep;39(9):1321-6.

9. Abell RG, Kerr NM, Vote BJ. Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology. 2013 May;120(5):942-8.

10. Serrao S, Lombardo G, Ducoli P, Rosati M, et al. Evaluation of femtosecond laser clear corneal incision: an experimental study. J Refract Surg. 2013 Jun;29(6):418-24.

11. Alió JL, Abdou AA, Soria F, Javaloy J, et al. Femtosecond laser cataract incision morphology and corneal higher-order aberration analysis. J Refract Surg. 2013 Sep;29(9):590-5.

12. Nagy ZZ, Takacs AI, Filkorn T, Kránitz K, et al. Complications of femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2014 Jan;40(1):20-8.

13. Schultz T, Joachim SC, Kuehn M, Dick HB. Changes in prostaglandin levels in patients undergoing femtosecond laser-assisted cataract surgery. J Refract Surg. 2013 Nov;29(11):742-7.

14. Laser-Assisted Cataract Surgery and CMS Rulings 05-01 and 1536-R. November 16, 2012. Available at: http://cms.hhs.gov/Medicare/Medicare-Fee-for-Service-Payment/ASCPayment/Downloads/CMS-PC-AC-IOL-laser-guidance.pdf. Accessed 01/13/2014.