Cataract Surgery

Femtosecond- Assisted Cataract Surgery:

Cataract surgery is the most widely performed intraocular procedure. As a result, techniques are under constant review.1, 2 The technique of cataract surgery has evolved from large-incision extracapsular extraction to microincision surgeries. Patient expectations also have changed, with an increasing emphasis on precise refractive as well as visual and safety outcomes. The recent introduction of femtosecond lasers to cataract surgery represents a potentially significant advance in cataract technology,3 but there is little published information about intraoperative complications, the surgical learning curve, and visual outcomes.

Femtosecond lasers have been used successfully in ophthalmic surgery since 2001.4, 5, 6, 7, 8

The technology has been applied as a surgical tool in corneal incisions,9, 10 wedge resections,11 tunnel creations,12 and penetrating and anterior lamellar keratoplasty.13, 14, 15 Femtosecond lasers have been noted to be more precise than highly sophisticated mechanical devices, with fewer likely collateral tissue effects.16 The preliminary reports on the intraocular use of femtosecond laser for cataract extraction are promising.17, 18 The reported benefits of femtosecond cataract surgery include higher precision of the capsulorrhexis and reduced ultrasound power used during the phacoemulsification.17, 18, 19 Femtosecond laser-created anterior capsulotomies also have been reported to show more regularity and better intraocular lens centration.20

Limitations of Traditional Phaco-Cataract Surgery:

Corneal incisions are manually executed and imprecise,
Extensive manipulation, phaco power and procedure time are associated with corneal edema, wound burn and endothelial cell loss
Capsulotomy size is directly related to Effective Lens Position (21,22)
Cataract surgery complications are still 10x that of LASIK (23,24)

Complications of Traditional Cataract Surgery: 

Novel approach in cataract surgery; Aims are improving:

• Precision
• Predictability
• Safety
• Efficacy

As patient demands have increased, the importance of effective lens position (ELP) has increased dramatically. New technology intraocular lenses (IOLs), including aspheric, toric, and multifocal IOLs, have also driven this need for improved ELP. A reproducible central and circular capsulorrhexis is a prerequisite for good postoperative ELP. Irregular capsulotomy might cause refractive surprises such as myopic or hyperopic shifts, unwanted surgically induced astigmatism (SIA), posterior chamber lens tilt, increase in higher order aberrations, and glare and halo phenomena as well.

Laser refractive cataract surgery with a femtosecond laser resulted in a significantly better predictability of IOL power calculation than conventional phacoemulsification surgery. This difference is possibly due to a more precise capsulorrhexis, resulting in a more stable IOL position.(25)

The ultrashort-pulse femtosecond lasers have been developed to increase the precision of and to minimize the collateral tissue damage in ocular surgery. Because power is a function of energy and time, the use of shorter pulses decreases the energy output and hence leads to better preservation of ocular structures. Recent experimental and human studies have reported the applicability of femtosecond lasers in cataract surgery.26, 27

Phacoemulsification surgery remains the standard for cataract extraction. Capsulorrhexis and nuclear disassembly are important steps during phacoemulsification.28,29

Currently four companies make a femtosecond laser with cataract application

• Alcon LenSx (Fort Worth, TX)
• LensAR (Winter Park, FL)
• Opti-medica ,Catalys(Santa Clara, CA)
• Victus,Bausch + Lomb Technolas PV (Munich Germany)

Main components of Laser systems:

•  Laser source, head and optics
•  Laser parameters
• Pulse duration
• Frequenccy
• Spot size
• Spot energy
• Image guidance
• Delivery system

Delivery systems:
Corneal interface

• Curved lens
• LenSx
• Victus
• Liquid
• Catalys
• LensAR

Image guidance system:Is a critical part of femto-cataract surgery

• Visualization and customization
• Determines the location and dimension of ocular structures
• Guides the surgeon to visualize and customize the placement of laser incisions and lens fragmentation zones

Lasers and imaging systems

• LenSx and Catalys
• FD-OCT for 3D high resolution vewing
• Victus
• Real time OCT for planning and monitoring
• LensAR
• 3-D Confocal Structured illumination (CSI), very similar to Sheimpflug imaging

Features of current Laser systems: 

Advantages of femto-cataract surgery:

• More accurate, precise and predictable corneal incions
• Reduced astigmatism and other wound related complications
• More accurate, precise and predictable anterior capsulotomy
• Less chance of capsular tear
• Improved effective lens position and
• refractive outcomes
• Less US energy
• More predictable and precise astigmatic incisions

Laser created incision:

• Precise tunnel and multiplane incision
• A more stable wound
• Better control during the surgery
• More stable fluid dynamics
• Less influx
• Fast healing
• Less risk of endophthalmitis

Disadvantages of FS Laser cataract surgery:

• Cost
• Slowing patients flow
• Not possible in small pupils < 5mm
• Not possible in opaque corneas and white milky cataracts
• Not possible in advanced glaucoma or in the presence of filtering bleb

Respect The Surgical Learning Curve

For all surgeries and all surgeons, a certain learning curve exists for any new technique. Everyone should acknowledge and respect stricter adherence to particular standards and rules during the learning curve, which appears to be approximately 30 to 50 eyes.

Before operating, patients should be screened for ocular surface issues that could complicate the laser docking and use. The corneal surface needs frequent wetting, especially in cases where the docking is tried multiple times, as can happen for the less experienced surgeon. Patients with recurrent epithelial erosions are not good candidates for initial femtosecond laser–assisted treatments due to the risk of epithelial sloughing, and severe diabetic patients might also have less healthy epithelium. The initial steps of femtosecond laser cataract surgery include stabilization of the patient’s eye with respect to the optical system of the laser. The various femtosecond lasers currently used for cataract surgery have different systems for docking. The LensAR has a motorized servocontrolled head with a nonapplanating suction fixation device that does not directly touch the cornea, whereas the OptiMedica Catalys uses a fluid-filled interface called liquid optics.30

All surgeries were performed under topical anesthesia with 0.4% oxybuprocaine. Pupillary dilation was achieved before surgery with 1% tropicamide, 10% phenylephrine, and 1% cyclopentolate (Minims; Chauvin Pharmaceuticals, Kingston-upon-Thames, Surrey, United Kingdom).
The initial steps for the procedure involve programming the lens, capsulotomy, primary incision, and secondary incision patterns. After all pattern selections and parameter choices are complete, the system is ready to dock to the patient.

The Alcon LenSx laser system uses a single-piece curved patient interface with an onboard vacuum system. The orientation of the patient interface always should be checked with respect to the laterality of the eye to be operated on. During the initial cases, some difficulty was noted while docking the system onto the patients’ eyes. This was improved by ensuring proper patient positioning, avoiding nasal interference, and increased verbal guidance to the patients regarding the target for fixation. The number of docking attempts was seen to improve significantly among successive patients. The other complication commonly noted in the patients was the occurrence of suction breaks. Five patients experienced a loss of suction during the laser procedure. In each case, the procedure was halted and the patient was taken to the operating room for completion of the surgery. This did not impact the surgical procedure or the final outcome.

Younger age, narrow palpebral apertures, and flat corneas were identified as risk factors. The incidence of suction breaks during IntraLase (AMO, Santa Ana, CA) has been reported to vary between 0.06% and 0.27%.31, 32, 33

Suction breaks that occur during the femtosecond laser delivery for cataract surgery should be recognized immediately. The appearance of a meniscus or redundant conjunctiva moving toward the applanated area represent clues that may help to identify an impending loss of suction. In the event of such a complication, the treatment should be halted immediately by releasing the foot switch because the margin of error is small, and surgery should be completed by shifting the patient to the operating room.

The focused femtosecond pulses induce optical breakdown with significantly less pulse energy than is required for longer pulses, thus minimizing the collateral tissue damage.34

The surgeon observes applanation of the cornea using the video microscope and then applies suction when the cornea is properly applanated, that is, when the applanation force indicator is in the yellow or green zone. The surgical display presents live microscopic and optical coherence tomography images of the anterior segment (Fig 1).

The control point settings now include limbal centration, marking the corneal incision boundaries, pupil centration, and identification of the depth and position of the lens as well as corneal surfaces.

Using the optical coherence tomography image, a selection is made with respect to capsulotomy peak and trough, lens offsets, corneal thickness, and wound tunnel length. The laser treatment then is started by pressing the foot switch, and the surgical progress is monitored on the video screen.

The procedure maybe stopped at any stage by releasing the foot switch.

The program delivers laser energy in a sequence of capsule, lens, and primary and secondary corneal incisions. Arcuate corneal incisions, if used, follow the secondary corneal incisions. control points.

Figure 1. Microscopic and ocular coherence tomography images of the anterior segment seen with LenSx. Left, Pattern positioning: primary incision (bright yellow), secondary incision (orange), capsulotomy (pink), and lens (dull yellow). Top right, Adjustment of the capsule pattern range. Bottom right, Adjustment of the anterior capsule depth and posterior capsule depth

The near infrared femtosecond pulses are not absorbed by optically clear tissues. The LenSx performs the procedures in a sequence of capsulotomy, lens fragmentation, and corneal incisions, respectively. The capsulotomy is performed in a cylindrical fashion propagating upward to prevent interference in subsequent laser pulses by the microbubbles generated. The expansion of the lens caused by the generation of gas bubbles may stretch and displace the lens capsule from its original position. So that the relatively narrow capsulotomy pattern does not miss its target, the lens fragmentation is performed after capsulotomy has been completed. The corneal incisions are the last steps to be completed before the patients are shifted from the laser suite to the operating room.
Corneal incisions that are square are significantly more resistant to deformation and leakage.35

In a pilot study, Masket et al 36 demonstrated that the corneal incisions created with the femtosecond laser are more stable. This is attributable to the controlled and more reproducible generation of more square incisions and the multiplanar configuration of the corneal wound created.

The energy settings at the start of this study for the capsulotomy settings were 15 μJ, with an anterior and posterior offset of 300 μm each, a tangential spot separation of 5 μm, and a layer separation of 3 μm.

These settings have continued to change after the initial 200 cases and reflect on surgeon preferences.
Although all capsulotomies were ranked as relatively easy to remove, in an attempt to improve the completeness of the capsulotomy created by the laser and to reduce the time taken to complete the procedure, the settings were amended further. Both offsets (anterior and posterior) were decreased to 150 μm, with a tangential spot separation of 4 μm and a layer separation of 3 μm. A greater posterior offset offers greater ablation of the anterior cortex. It is likely that the surgeons with femtosecond laser experience who were accustomed to dealing with a suction fixation device were less troubled by this problem in their initial cases.

Tackman et al reported that approximately half of the cases operated with the femtosecond laser had free-floating capsulotomies requiring no manual detachment from the remaining capsule.

In addition to the greater precision, the capsulotomies created by the femtosecond laser have been reported to be stronger than the manual capsulorrhexis in terms of capsular edge strength.17, 18, 19

Anterior capsular tags were noted at the margin of the capsulotomy opening in approximately 10% of the cases. Marques et al38 reported a much lower anterior capsular tear rate of 0.79% during routine phacoemulsification. Thus, it is important that these notches are identified and guided manually with forceps to maintain the curvilinearity of the capsulotomy opening to prevent equatorial and posterior extension of these tears. Familiarity with the femtosecond-created capsulotomy removal again has reduced the frequency of this issue.
Posterior capsular tears were seen in 3.5% of cases and posterior dislocation of the nucleus or nuclear fragments were seen in 2% of cases. there was a trend toward a general reduction of these complications with experience. This has been confirmed with higher surgery numbers. These are much higher than the rates of these complications reported during phacoemulsification; posterior capsular tears have been reported to vary between 0.53% and 1.9%,39, 40, 41, 42 whereas the incidence of a dropped nucleus has been reported to be between 0.1% and 0.12%.42, 43

Thus, the importance of manually checking the capsulotomy for completion and stabilization of the eye by injection of viscoelastics through the side port before opening the main incision cannot be overemphasized.

The authors observed that cortical removal in femtosecond cataract surgery took longer and required greater manipulation. Whether the energy produced by the femtosecond laser has some effect on the cortical fibers and the posterior capsule remains to be evaluated by histologic studies. The cause for the posterior lens dislocation in the other 2 cases was identified as intraoperative capsular block. The laser settings for lens fragmentation included an anterior offset of 700 μm and a posterior offset of 800 μm. There was no evidence of photodisruption of the posterior capsule as evaluated during the pars plana vitrectomy and phacofragmentation. The gases entrapped within the crystalline lens during photodisruption may increase intracapsular pressure. Subsequent hydrodissection further increases the pressure, resulting in a posterior capsular blowout. The heating and increased adherence of the cortex to the capsular edge also may contribute to this syndrome. Thus, it needs to be emphasized that hydrodissection should be performed after adequate decompression of the anterior chamber, be gentle, and be performed with a large-bore cannula. Additional precautions, such as completing nuclear fracture centrally to allow any retrolenticular gas to escape, also should be considered. The sudden constriction of the pupil, wrinkling of the capsule, and tilting of the lens are the first signs that posterior capsular rupture may have occurred and may help identify these cases for further management. With experience and adherence to these precautions, this complication has been overcome at the authors’ center.
The time taken to complete the surgery increased initially with the laser-assisted group compared with the routine phacoemulsification cohort. This additional time during surgery may have been a contributing factor to the initial rise in complications; however, there seemed to be no significant correlation.
Successful completion of a case of femtosecond-assisted cataract surgery does produce a superior wound and a more circular and more consistently sized capsulotomy and probably contributes to a reduction in the average phacoemulsification time, as described previously in the literature.17, 18

Corneal wounds should be well designed before surgery to avoid tension and rupture intraoperatively, which could result in increased SIA and wound leak. Wounds created with the femtosecond laser seem to be tighter compared to ones created with blades.

Following the contour of the capsulotomy created by the femtosecond laser until it is clear that the anterior capsule is fully detached and free- floating in the anterior chamber. Small tags or bridges may not be apparent to the inexperienced surgeon, and an anterior tear might occur with resulting unwanted complications if this is not recognized, including capsular blockage syndrome with posterior capsular tear, which can arise from issues with anterior capsule removal or abrupt hydrodissection with a large cannula as opposed to smooth hydrodissection with a small diameter cannula. The “rock-and-roll” technique is also useful to avoid this complication: following smooth hydrodissection, the nucleus is gently pressed down and rolled, allowing intralenticular gas bubbles to escape toward the anterior chamber.

Femto-fragmentation might use a laser beam cross pattern or multiple cuts within the lens (6, 8, or more) referred to as a “cake-pattern” or “pizza-pattern.”10 Cubicles might also be formed within the nucleus.44

Sequences of treatment:

The three companies differ in the order of incision delivery.

The OptiMedica & LensAR system delivers the capsulotomy first and then the lens fragmentation pattern.

This sequence reduces the risk of tearing the capsular bag or creating zonular dehiscence because the lens is allowed to relax as it is fragmented.

With the LenSx system, the lens is fragmented, the capsule is re-imaged for expansion, then the capsulotomy is made.

Difficulties/Complications During Laser Procedure:45

Mean no. of Docking Attempts Per Patient; 1.5

Suction Break

Difficulties/Complications During Phacoemulsification:

Corneal Incision Assisted with Keratome; 15%
Pupillary Constriction;
Anterior Capsulotomy Tags ; 10%
Anterior Radial Tears; 4%
Posterior Capsular Tear and Vitreous Loss; 3.5%
Posterior Lens Dislocation; 2%
Cases with Free-floating Capsulotomies; 17.5%

Bar graph showing comparative evaluation across surgeons with respect to the different complications observed.

“There’s vitreous loss in 4%-6% of cataract cases

In creating the capsulorhexis and in pre-chopping the nucleus, reducing the overall energy needed to remove the cataract. “The femtosecond is a more accurate, reproducible, natural evolution of this technology,”

There are three potential sources for error in creating a capsulorhexis: the shape, the size, and the positioning. “In the more modern IOLs and IOLs to come, those variables will be more important,”

Dr. Nichamin said. The “brilliance” of these lasers is their ability to segment the nucleus into smaller fragments, “so all it takes is the aspiration alone to get the cataract out of the bag,” Dr. Vukich said. “Less energy is needed, you’re less likely to put stress on the zonules or traumatize the capsular bag, etc.

Using a femtosecond laser will “not only make the procedure safer, but it decreases the amount of phaco energy,” Dr. Nagy said. “We can cut the lens into four quadrants without any phaco energy, so the temperature rise will be lower, which is good for the endothelial cells.”There is a “great deal of variability” in how surgeons create wounds, Dr. Nichamin said, and that variability lies directly in the surgeon’s hands. “We know the best wound architecture is square, that they’re far more stable and strong than rectangular wounds.

“LenSx is using optical coherence tomography,” he said, adding the LensAR is using Scheimpflug imaging, “which may or may not offer potential advantages.”Dr. Culbertson added the Optimedica laser “uses real time intraoperative OCT [optical coherence tomography] visualization to determine the relevant dimensions of the anterior chamber and the thickness of the cornea and the lens.46

Pricing considerations Most anterior segment surgeons have recognized “the safety and stability of using the femtosecond laser in LASIK, and it’s a short extension to see its benefits for cataract surgery,”
These lasers “facilitate premium implants,” Dr. Vukich said. “Patients want the best implant and want the best laser possible for those implants.

Femto-cataract is an easy, reliable and safe procedure to perform capsulotomy and lens fragmentation

Comparison between femto and manual capsulotomy shows:

Higher predictability in capsulotomy diameter

Better circularity
Better centration

Lens fragmentation may reduce required phaco power

Arcuate incisions can compensate for induced cylinder and reduce corneal astigmatism

Lens fragmentation may reduce required phaco power
Arcuate incisions can compensate for induced cylinder and reduce corneal astigmatism

Value appriximate.: 550,000 $
Service cost: 40,000$ annually after the first year
Patients fee of 425 $

References:

1. Semmens JB , Li J , Morlet N , Ng J teamEPSWA . Trends in cataract surgery and postoperative endophthalmitis in Western Australia (1980–1998): the Endophthalmitis Population Study of Western Australia . Clin Experiment Ophthalmol . 2003;31:213–219
2. Erie JC , Baratz KH , Hodge DO , et al. Incidence of cataract surgery from 1980 through 2004: 25-year population-based study . J Cataract Refract Surg . 2007;33:1273–1277
3. He L , Sheehy K , Culbertson W . Femtosecond laser-assisted cataract surgery . Curr Opin Ophthalmol . 2011;22:43–52
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;14:347–355 xviii–ix
5. Kezirian GM , Stonecipher KG . Comparison of the IntraLase femtosecond laser and mechanical keratomes for laser in situ keratomileusis . J Cataract Refract Surg . 2004;30:804–811
6. Gil-Cazorla R , Teus MA , de Benito-Llopis L , Mikropoulos DG . Femtosecond laser vs mechanical microkeratome for hyperopic laser in situ keratomileusis . Am J Ophthalmol . 2011;152:16–21
7. Sutton G , Hodge C . Accuracy and precision of LASIK flap thickness using the IntraLase femtosecond laser in 1000 consecutive cases . J Refract Surg . 2008;24:802–806
8. Kim P , Sutton GL , Rootman DS . Applications of the femtosecond laser in corneal refractive surgery . Curr Opin Ophthalmol . 2011;22:238–244
9. Harissi-Dagher M , Azar DT . Femtosecond laser astigmatic keratotomy for postkeratoplasty astigmatism . Can J Ophthalmol . 2008;43:367–369
10. Nubile M , Carpineto P , Lanzini M , et al. Femtosecond laser arcuate keratotomy for the correction of high astigmatism after keratoplasty . Ophthalmology . 2009;116:1083–1092
11. Ghanem RC , Azar DT . Femtosecond–laser arcuate wedge-shaped resection to correct high residual astigmatism after penetrating keratoplasty . J Cataract Refract Surg . 2006;32:1415–1419
12. Ertan A , Kamboruglu G , Akgün U . Comparison of outcomes of 2 channel sizes for intrastromal ring segment implantation with a femtosecond laser in eyes with keratoconus . J Cataract Refract Surg . 2007;33:648–653
13. Price FW , Price MO , Grandin JC , Kwon R . Deep anterior lamellar keratoplasty with femtosecond-laser zigzag incisions . J Cataract Refract Surg . 2009;35:804–808
14. Prakash G , Jacob S , Ashok Kumar D , et al. Femtosecond-assisted keratoplasty with fibrin glue-assisted sutureless posterior chamber lens implantation: new triple procedure . J Cataract Refract Surg . 2009;35:973–979
15. Buzzonetti L , Laborante A , Petrocelli G . Refractive outcome of keratoconus treated by combined femtosecond laser and big-bubble deep anterior lamellar keratoplasty . J Refract Surg . 2011;27:189–194
16. Sugar A . Ultrafast (femtosecond) laser refractive surgery . Curr Opin Ophthalmol . 2002;13:246–249
17. Nagy Z , Takacs A , Filkorn T , Sarayba M . Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery . J Refract Surg . 2009;25:1053–1060
18. Palanker DV , Blumenkranz MS , Andersen D , et al. Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography . Sci Transl Med . 2010;2: 58ra85
19. Friedman NJ , Palanker DV , Schuele G , et al. Femtosecond laser capsulotomy . J Cataract Refract Surg . 2011;37:1189–1198
20. Nagy ZZ , Kránitz K , Takacs AI , et al. Comparison of intraocular lens decentration parameters after femtosecond and manual capsulotomies . J Refract Surg . 2011;27:564–569
21. Norrby S. Sources of error in intraocular lens power calculation. J Cataract Refract Surg. 2008 Mar;34(3):368-76.
22. Cekiç O, Batman C. The relationship between capsulorhexis size and anterior chamber depth relation. Ophthalmic Surg Lasers. 1999 Mar;30(3):185-90
23. Pereira et al. JCRS 2006 Oct;32(10):1661-6
24. Park et al. Ophthalmic Surg Lasers Imaging. 2010 Mar-Apr;41(2):236-41
25. Filkorn T, Kovács Iet al. J Refract Surg. 2012 Aug;28(8):540-4.
26. Nagy Z , Takacs A , Filkorn T , Sarayba M . Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery . J Refract Surg . 2009;25:1053–1060
27. Palanker DV , Blumenkranz MS , Andersen D , et al. Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography . Sci Transl Med . 2010;2: 58ra85
28. Taravella MJ , Davidson R , Erlanger M , et al. Characterizing the learning curve in phacoemulsification . J Cataract Refract Surg . 2011;37:1069–1075
29. Prakash G , Jhanji V , Sharma N , et al. Assessment of perceived difficulties by residents in performing routine steps in phacoemulsification surgery and in managing complications . Can J Ophthalmol . 2009;44:284–287
30. He L , Sheehy K , Culbertson W . Femtosecond laser-assisted cataract surgery . Curr Opin Ophthalmol . 2011;22:43–52
31. Davison JA , Johnson SC . Intraoperative complications of LASIK flaps using the IntraLase femtosecond laser in 3009 cases . J Refract Surg . 2010;26:851–857
32. Binder PS . One thousand consecutive IntraLase laser in situ keratomileusis flaps . J Cataract Refract Surg . 2006;32:962–969
33. Vogel A , Schweiger P , Frieser A , et al. Intraocular Nd:YAG laser surgery: laser-tissue interaction, damage range, and reduction of collateral effects . IEEE J Quantum Electron . 1990;26:2240–2260
34. Vogel A , Schweiger P , Frieser A , et al. Intraocular Nd:YAG laser surgery: laser-tissue interaction, damage range, and reduction of collateral effects . IEEE J Quantum Electron . 1990;26:2240–2260
35. Ernest PH , Kiessling LA , Lavery KT . Relative strength of cataract incisions in cadaver eyes . J Cataract Refract Surg . 1991;17(suppl):668–671
36. Masket S , Sarayba M , Ignacio T , Fram N . Femtosecond laser-assisted cataract incisions: architectural stability and reproducibility [letter] . J Cataract Refract Surg . 2010;36:1048–1049
37. Tackman RN , Kuri JV , Nichamin LD , Edwards K . Anterior capsulotomy with an ultrashort-pulse laser . J Cataract Refract Surg . 2011;37:819–824
38. Marques FF , Marques DM , Osher RH , Osher JM . Fate of anterior capsule tears during cataract surgery . J Cataract Refract Surg . 2006;32:1638–1642
39. Chan FM , Mathur R , Ku JJ , et al. Rates of posterior capsule rupture during cataract surgery among different races in Singapore . Ann Acad Med Singapore . 2006;35:698–700
40. Jaycock P , Johnston RL , Taylor H , et al. UK EPR User Group The Cataract National Dataset electronic multi-centre audit of 55,567 operations: updating benchmark standards of care in the United Kingdom and internationally . Eye (Lond) . 2009;23:38–49
41. Zaidi FH , Corbett MC , Burton BJ , Bloom PA . Raising the benchmark for the 21st century—the 1000 cataract operations audit and survey: outcomes, consultant-supervised training and sourcing NHS choice . Br J Ophthalmol . 2007;91:731–736
42. Misra A , Burton RL . Incidence of intraoperative complications during phacoemulsification in vitrectomized and nonvitrectomized eyes: prospective study . J Cataract Refract Surg . 2005;31:1011–1014
43. Clark A , Morlet N , Ng JQ , et al. Whole population trends in complications of cataract surgery over 22 years in Western Australia . Ophthalmology . 2011;118:1055–1061
44. Zoltan Z. Nagy, MD, DSC. Femtolaser Cataract Surgery: How to Evaluate This Technology, Read the Literature, and Avoid Possible Complications. J Refract Surg.2012,Vol. 28, No. 12, 855-857
45. Shveta Jindal Bali, MBBS, MD, Early Experience with the Femtosecond Laser for Cataract Surgery, Ophthalmology Volume 119, Issue 5 , Pages 891-899, May 2012.
46. Edtiors’ note: Drs. Steinert, Nagy, and Slade have financial interests with LenSx (Aliso Viejo, Calif). Dr. Culbertson has financial interests with Optimedica (Santa Clara, Calif.). Dr. Vukich has financial interests with Optimedica (Santa Clara, Calif.). Dr. Nichamin has financial interests with LensAR (Winter Park, Fla.).
47. Michael A. Lawless, MBBS, FRANZCO, FRACS ,Complications of Laser Cataract Surgery, Cataract & refractive Surgery today ,EUROPE ,April 2013,Page;34-36

Complications of Laser Cataract Surgery

A group practice’s experience improving the safety and outcomes of both complex and routine cataract procedures performed with the femtosecond laser.

By Michael A. Lawless, MBBS, FRANZCO, FRACS

Cataract surgery is the world’s most commonly performed eye operation. Femtosecond laser technology aims to improve the safety and accuracy of the procedure for patients, including those with an advanced cataract or who need a refractive lensectomy.

The key steps of manual phacoemulsification can have an impact on the surgery’s safety. In particular, the quality of the anterior capsulotomy influences the rate of complications and is one of the most difficult steps for trainees and inexperienced surgeons to master.1 In contrast, when combined with high-resolution anterior segment imaging, laser technology can improve the safety profile of cataract surgery by creating more consistent main and sideport incisions and a more reproducible capsulorrhexis with less chance of an anterior capsular tear. The laser can also fragment or soften the nucleus2 and has the ability to precisely place intrastromal corneal incisions to treat astigmatism. These incisions may be left intrastromally or opened in the OR or postoperatively to augment their effect, if needed.

Since the first report of laser cataract surgery in 2009, considerable progress has been made in terms of software development. These advancements, combined with more surgical experience with laser cataract surgery, have led to reduced phacoemulsification time, better wound architecture, greater precision and accuracy of the anterior capsulotomy, and more stable and predictable positioning of the IOL.3-7

Results Of A Group Practice Study

Our group at Vision Eye Institute in Sydney, Australia, reported a short learning curve with laser cataract surgery. 8-10  In a subsequent single-center, consecutive cohort study, we examined the rate of complications in a large prospective series of cases performed by six surgeons who had experience with laser cataract procedures. We analyzed the complication rates and compared them with the initial learning curve.11  All procedures were performed with the LenSx Laser (Alcon Laboratories, Inc.) under topical anesthesia. Patients with corneal opacities or poorly dilating pupils (< 5 mm), advanced glaucoma, hypotony, narrow palpebral fissures, and nystagmus or hemifacial spasm that prevented the docking rings’ placement, were excluded.

In group 1 (the first 200 eyes) 74.5% of eyes underwent a complete laser cataract procedure that included a laser capsulotomy, lens fragmentation, and corneal incisions. Five eyes (2.5%) had suction breaks during the laser procedure, and 21 eyes (10.5%) had anterior capsular tags. The incidence of capsular complications (anterior and posterior tears) was 7.5% (15/200), and the incidence of posterior lens dislocation was 2% (4/200). The mean number of docking attempts was 1.5 per eye.

In group 2 (the next consecutive 1,300 eyes), an anterior capsulotomy, lens segmentation, and main and sideport corneal incisions were successfully completed in 1,280 eyes (98.5%). In addition to routine preoperative dilating drops, all eyes received one drop of 10% phenylephrine immediately after the laser procedure. Eyes are mildly inflamed after the laser cataract surgery, and phenylephrine drops maintain good pupillary dilatation while patients are transferred to the OR. With this technique, only 16 eyes (1.23%) had constricted pupils after the laser procedure. Twenty-five eyes (1.92%) required corneal incisions manually created with a keratome, either due to suction breaks, an air meniscus, or because the incisions made with the laser could not be easily opened. The mean number of docking attempts was 1.05 per eye. We learned that docking is crucial for the case to go smoothly. The increase in IOP is minimal, and the procedural time is short; therefore, it is worthwhile to redock if the original attempt is not ideal.

On a scale of 1 to 10, with 1 indicating great difficulty and 10 indicating a free-floating capsulotomy, the ease with which the anterior capsule was removed was rated at least 8 in 100% of cases. A free-floating capsulotomy or postage stamp configuration (small areas of nonperforation not affecting the complete removal of the capsular button) was present in 96% of cases.

Other Complications

The anterior capsulotomy button was incomplete in 52 cases (4%), and in these cases, a manual capsulorrhexis was required to complete the capsulotomy. Anterior capsular tags were seen in 21 eyes (1.62%) after the capsulotomy button was removed. In four eyes (0.31%), capsular tags led to extension and formation of radial anterior capsular tears. These tears extended to the posterior capsule in two eyes, with one eye requiring an anterior vitrectomy. The overall incidence of posterior capsular tears was 0.31% (4/1,300), with two cases occurring during phacoemulsification. Three cases of vitreous loss were successfully managed with a bimanual anterior vitrectomy and the implantation of an IOL in the sulcus. There were no cases of posterior lens dislocation or capsular block syndrome.

Not surprisingly, a significantly lower rate of complications occurred after the first 200 eyes when the surgeons became familiar with the technology. The rate of major capsular complications (anterior and posterior tears) decreased from 7.5% in group 1 to 0.62% in group 2. Surgeon experience, the addition of one drop of 10% phenylephrine immediately after the procedure, and technical improvements made to the LenSx Laser System contributed to an overall decrease in complication rates.

Lessons Learned

During the course of this study, we became proficient at managing the different operative environments by releasing gas and decompressing the capsular bag before commencing phacoemulsification, mobilizing the nuclear segments, and modifying the I/A technique for the removal of the lens cortex. Each surgeon developed a slightly different technique. For example, some performed hydrodissection before releasing intracapsular gas, while others completed this step afterward. In some cases, hydrodissection was eliminated, and the nuclear segments were mobilized by using the laser-generated gas cleavage plane between the nucleus and the cortex (pneumodissection).

There is some evidence that a laser-created capsulotomy may be stronger than a continuous tear capsulorrhexis created manually. If there is a microtag, it can be stretched and torn during intracapsular manipulation. We recommend inspecting the edge of the laser cut capsulotomy for a capsular tag under high magnification before phacoemulsification. If there is any doubt, assume that the anterior capsule has not been uniformly cut and use forceps to mobilize the capsule. It is tempting to assume that all capsules are free-floating and perfect, and that simply inserting the phaco tip and aspirating the capsule will be sufficient. In most cases, this is true, but occasionally this approach can lead to problems that could have been prevented by a more careful removal of the capsule with forceps.

It is helpful to inspect the gas pattern as well. Sometimes, the gas will escape anteriorly into the anterior chamber, and there will be little or no gas within the nucleus itself. At other times, particularly in hard grade 4 nuclei, gas will become trapped behind the nucleus, and care must be taken to avoid capsular block syndrome, which occurs because of increased pressure within the capsular bag. Any additional pressure within the capsular bag can cause the posterior capsule to blow out. If the surgeon is suspicious of gas trapped behind the nucleus, a few simple maneuvers such as decompressing the anterior chamber prior to gentle hydrodissection with minimal fluid, splitting the hemispheres, or mobilizing the nuclear fragments to allow gas to escape before hydrodissection will prevent capsular block syndrome.

Conclusion

These data reflect a group practice’s experience, which tends to better mirror the real world compared with a single surgeon’s best case series. We used the same selection for all 1,500 eyes. Only a few small-pupil cases were excluded. Eyes with intraoperative floppy iris syndrome, pseudoexfoliation, traumatic zonulopathies, white cataract, and mild to moderate corneal opacities were included. Eyes that had undergone previous trabeculectomy or penetrating keratoplasty were also included in the study.

If we consider that the community rate for posterior capsular tear is 2%,12 then we now have a procedure that allows a group of surgeons to perform cataract surgery more safely than the community rate and is comparable to or better than the best single-surgery studies reported in the literature.

Five Tips For perForming a saFe Laser CaTaraCT surgery

• Use minimal topical anesthesia. Only one drop of anesthesia is needed to perform the laser portion of the procedure. Any more than this may cause the epithelium to be hazy and the surgical view less than ideal.
• Well-centered docking is critical. A well-centered dock allows the temporal corneal incision to be performed,
  minimizes time and laser energy, and lessens the likelihood of a cascading set of problems.
  Do not be afraid to re-dock if the first attempt is not ideal, and make use of Bell’s phenomenon when attempting to dock.
• Do not assume that the capsulorrhexis is perfect. In the rare instance in which there is a tag or an adhesion, it is better to use capsulorrhexis forceps so that it does not become a problem.
• Less is more at every step. I recommend using less viscoelastic and performing less hydrodissection than in manual cataract surgery. During hydrodissection, use minimal fluid in a decompressed eye.
• Recognize gas patterns. Learn to recognize the different intracapsular gas patterns, and modify your technique accordingly.

Michael A. Lawless, MBBS, FRANZCO, FRACS, is Medical Director of the Vision Eye Institute in Chatswood, New South Wales, Australia. Dr. Lawless may be reached at +61 2 9424 9999; e-mail: michael.lawless@ visioneyeinstitute.com.au.

1. Dooley IJ, O’Brien PD. Subjective difficulty of each stage of phacoemulsification cataract surgery performed by basic surgical trainees. J Cataract Refract Surgery. 2006;32:604-608.
2. Nagy Z, Takacs A, Filkorn T, Sarayba M. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg. 2009;25:1053-1060.
3. Kranitz K, Mihaltz K, Sandor GL, et al. Intraocular lens tilt and decentration measured by Scheimpflug camera following manual or femtosecond laser-created continuous circular capsulotomy. J Refract Surg. 2012;28:259-263.
4. Mihaltz K, Knorz MC, Alio JL, et al. Internal aberrations and optical quality after femtosecond laser anterior capsulotomy in cataract surgery. J Refract Surg. 2011;27: 711-716.
5. Kranitz K, Takacs A, Mihaltz K, et al. Femtosecond laser capsulotomy and manual continuous curvilinear capsulorhexis parameters and their effects on intraocular lens centration. J Refract Surg. 2011;27:558-563.
6. Palanker DV, Blumenkranz MS, Andersen D, et al. Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography. Sci Transl Med. 2010; 2:58ra85.
7. Friedman NJ, Palanker DV, Schuele G, et al. Femtosecond laser capsulotomy. J Cataract Refract Surg. 2011;37:1189-1198.
8. Roberts TV, Lawless M, Chan CC, et al. Femtosecond laser cataract surgery: technology in clinical practice [published online ahead of print July 12, 2012]. Clin Experiment Ophthalmol. doi: 10.1111/j.1442-9071.2012.02851.x.
9. Bali SJ, Hodge C, Lawless M, et al. Early experience with the femtosecond laser for cataract surgery. Ophthalmology. 2012;119(5):891-899.
10. Roberts TV, Sutton G, Lawless MA, et al. Capsular block syndrome associated with femtosecond laser assisted cataract surgery. J Cataract Refract Surg. 2011;37: 2068-2070.
11. Roberts TV, Lawless M, Bali SJ, et al. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1,500 consecutive cases. Ophthalmology. 2013;120(2):227-233.

Lundström M, Behndig A, Kugelberg M, et al. Decreasing rate of capsule complications in cataract surgery: eight-year study of incidence, risk factors, and data validity by the Swedish National Cataract Register. J Cataract Refract Surg. 2011;37:1762-1767