ARTICLE
Femtosecond laser–assisted cataract surgery in intumescent white cataracts Ina Conrad-Hengerer, MD, Fritz H. Hengerer, MD, PhD, Stephanie C. Joachim, MD, Tim Schultz, MD, H. Burkhard Dick, MD, PhD
PURPOSE: To evaluate the feasibility and safety of femtosecond laser–assisted capsulotomy in eyes with intumescent white cataract. SETTING: Ruhr University Eye Clinic, Bochum, Germany. DESIGN: Prospective clinical trial. METHODS: After femtosecond laser–assisted capsulotomy (Catalys Precision system), phacoemulsification was performed using pulsed ultrasound energy and the effective phacoemulsification time was evaluated. The lenticular capsule disk was stained intraoperatively with trypan blue and pulled out using a microsurgical forceps for further analysis of form and shape. RESULTS: Twenty-five eyes were included in this trial. Automatic optical coherence tomography detection of the anterior capsule was performed successfully in all eyes. Radial anterior tears occurred in 2 eyes, an adherent tongue-like capsule adhesion in 9 eyes, and an incomplete capsulotomy button in 3 eyes. In all cases, the intraocular lens was centered and the implantation was uneventful. The mean deviation from the target diameter of the extracted capsule disks was 60 mm G 44 (SD). CONCLUSION: The use of the femtosecond laser–assisted system for capsulotomy in surgery for intumescent white cataract appears to be safe and technically feasible. Financial Disclosure: Dr. Dick is a member of the medical advisory board of Optimedica Corp. No other author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2014; 40:44–50 Q 2013 ASCRS and ESCRS
One of the most challenging situations in anterior segment surgery is the removal of an intumescent white cataract. A mature white cataract may have increased intracapsular pressure due to liquefaction of the cortex and a hard or brunescent nucleus underlying an anterior and/or posterior cortical opacity. The most difficult step of cataract surgery in hypermature intumescent cases is performing a safe continuous Submitted: June 4, 2013. Final revision submitted: August 9, 2013. Accepted: August 13, 2013. From the Institute for Vision Science (Conrad-Hengerer, Joachim, Schultz, Dick), Ruhr University Eye Clinic, Bochum, and the Goethe University Eye Clinic (Hengerer), Frankfurt, Germany. Corresponding author: Ina Conrad-Hengerer, MD, Institute for Vision Science, Ruhr University Eye Hospital, In der Schornau 23–25, 44892 Bochum, Germany. E-mail: ina.conrad-hengerer@ kk-bochum.de.
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curvilinear capsulorhexis (CCC) without further anterior capsule complications.1,2 Even after capsule staining with trypan blue to increase visualization and reduce the elasticity of the anterior capsule,3 puncture of the capsule can lead to uncontrollable extension of the opening, which is known as the Argentinean flag sign. The structural causes of tensile weakness were confirmed with ultrastructural analysis of the anterior capsule of intumescent cataract, showing no increase in thickness but extrusions of basement membrane filaments at the basement membrane–epithelial border.4 Given the surgical challenges of capsulorhexis in intumescent white cataracts, we assessed the feasibility and safety of femtosecond laser capsulotomy in these patients. PATIENTS AND METHODS In this study, patients with intumescent white cataract were scheduled for elective unilateral standard phacoemulsification without laser lens fragmentation and intraocular lens 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2013.08.044
FEMTOSECOND LASER–ASSISTED SURGERY FOR WHITE CATARACT
(IOL) implantation by the same surgeon (H.B.D.) from December 2011 to June 2012 at the Department of Ophthalmology, University of Bochum, Germany. The study received approval of the Ethics Committee, Ruhr University of Bochum, and all aspects of the Declaration of Helsinki were observed. All enrolled patients had a visually significant intumescent white cataract and were willing to volunteer for the prospective trial after giving written informed consent. The exclusion criteria included a history of serious coexisting ocular disease (eg, uncontrolled glaucoma, optic atrophy, or ocular tumors), relevant corneal opacities, age less than 22 years, and participation in another clinical study. The Lens Opacities Classification System III nuclear opalescence (NO) grading score5 was used. Preoperative NO was estimated by an independent physician using a BQ 900 slitlamp (Haag-Streit) at maximum illumination without light filtering. The IOL power calculations were performed using noncontact partial coherence laser interferometry (IOLMaster, Carl Zeiss Meditec AG) in the contralateral eye and ultrasound (US) biometry.6,7 Intraoperative measurements included the attachment of the anterior capsule, anterior capsule tears, posterior capsule ruptures, and the absolute and effective phacoemulsification times.
Surgical Technique The femtosecond laser treatment was applied before US phacoemulsification and IOL implantation. All patients were placed in a reclined chair and positioned supine beneath the system. The 2-piece Liquid Optics Interface8,9 of the Catalys Precision femtosecond laser system (Optimedica Corp.), which consists of a suction ring and a nonapplanating immersion lens, was engaged by the surgeon. The surgeon controlled the patient chair using video imaging for alignment. Once suction was confirmed, the system automatically measured the dimensions of the anterior chamber and the lens using 3-dimensional spectral-domain OCT, which identified the ocular surfaces and created laser exclusion zones. Standard safety zones contain a distance limit to the pupil margin of 500 mm to avoid accidental laser damage of the iris. The results were displayed to the surgeon for verification (Figure 1). At this point, the surgeon could also use the video graphic user interface to reposition and/ or redesign the capsulotomy.10 In this clinical trial, the following parameters were used: capsulotomy diameter between 4.5 mm and 5.0 mm, horizontal spot spacing of 5 mm, vertical spot spacing of 10 mm, pulse energy of 4 mJ, and incision depth of 1000 mm. Because of the known limited efficacy of the femtosecond laser in opaque white tissue, no lens fragmentation or softening patterns were used. Once the surgeon verified all relevant parameters, he began the selected treatment (Figure 2). All patients had small-incision phacoemulsification using topical anesthesia and a 2.75 mm wide clear corneal incision. The corneal incisions were not available on the laser system at the time of protocol development and institutional review board review (December 2011), so they were created manually. The 2-step clear corneal main incision was created at 12 o'clock using a 2.75 mm metal keratome (Slit Knife, 2.75 angled, Alcon Laboratories, Inc.). The single-plane side-port incisions were placed at 9 o'clock and 3 o'clock and made with a 1.2 mm metal keratome (Side-port knife,
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Figure 1. Three-dimensional spectral-domain OCT without (A) and with (B) detection-overlay of the anterior and posterior corneal surface as well as the anterior capsule. The posterior capsule is not detected because of the fluid milky lenticular content, with intralenticular spaces (black) representing high intracapsular pressure.
dual bevel, 1.2 angled, Alcon Laboratories, Inc.). Trypan blue (Vision Blue, Dutch Ophthalmic) was injected to stain the capsule while keeping the anterior chamber deep. Then, the first step was to instill sodium hyaluronate 1.0% (Healon) into the anterior chamber via the paracentesis to maintain the anterior chamber once the cannula was advanced to the opposite angle. The cannula was then moved to the middle of the lens capsule and pressed downward with the tip of the cannula at the center of the capsule. This downward motion indents the capsule disk, pulls it gently centrally, separates the free edge from the surrounding peripheral capsule, and confirms that there is a continuous 360-degree cut with a free flap (Figure 3). The anterior capsule disk was extracted in all cases using a Koch microforceps (Geuder AG) for further histopathologic evaluation. This procedure was followed by phacoemulsification using the stop-and-chop technique or bimanual aspiration only. Ultrasound phacoemulsification was performed using the same phacoemulsification machine (Stellaris, Bausch & Lomb). Without enlarging the corneal tunnel, a heparin-coated preloaded hydrophobic acrylic IOL (Polylens H10, Polytech Ophthalmologie GmbH) was injected into the capsular bag. After careful removal of the ophthalmic viscosurgical device (OVD) and watertight incisions were achieved, all eyes were covered with a patch. Standard topical ofloxacin and dexamethasone eyedrops were administered 4 times daily for the first week. Then, the ofloxacin was discontinued and the dexamethasone dosage was gradually decreased over 6 weeks.
Lens Capsule Analysis After careful removal, the lens capsule disks were placed in reaction tubes filled with fortified balanced salt solution (BSS, Alcon Laboratories, Inc.). They were mounted on glass
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Figure 2. Screenshot of the infrared camera during femtosecond laser capsulotomy in a normal case (A) and in an intumescent cataract (B) with high intracapsular pressure. Note the localized milky fluid leakage out of the lens into the anterior chamber.
slides and stained with 0.5% trypan blue (Sigma-Aldrich Co.). The stained capsules were rinsed with phosphatebuffered saline (Aesku.Diagnostics GmbH & Co. KG ) and fixed with Eukitt (Kindler GmbH) after a short drying period. Microscopic images were captured digitally using an Axiocam HRcCCD camera on a Zeiss Imager M1 microscope (Carl Zeiss Meditec AG). The diameters of the capsule disk samples were measured using Axiovision software (version 4.8, Carl Zeiss Meditec AG).
Outcome Measures The main outcome measures were accuracy of the capsulotomy, presence of adhesions, and incidence of anterior and posterior tears. Furthermore, the capsulotomy disk size and the histopathologic cut quality and texture were examined. The automatic detection capability of optical coherence tomography (OCT) imaging of the femtosecond laser system for the anterior and posterior capsule was noted.
Statistical Analysis All descriptive statistical analysis was performed using SPSS software (version 19.0, SPSS, Inc.). Continuous variables were described as mean, standard deviation (SD), median, minimum, and maximum values.
RESULTS The clinical trial enrolled 25 eyes (13 right [52%]). The mean age of the 15 men (60%) and 10 women (40%) was 69 years G 14 (SD). In 12 eyes, capsule tags occurred. In 3 eyes, the capsulotomy was not free and small adhesions could be clearly visualized using trypan blue staining before they were removed. Furthermore, in 9 eyes a tongue-like capsule adherence was observed intraoperatively at the rim of the capsulotomy (Figures 4 and 5). In 2 eyes, an anterior tear occurred during phacoemulsification; however, the liquefied lens material was successfully removed. No posterior extension or posterior capsule tears occurred. An incomplete cut from 5 to 7 o'clock was detected in a Morgagnian cataract. The target capsulotomy size was 5.0 mm; however, the final programmed diameter was slightly smaller in some cases based on pupil dilation and the 500 mm safety zone to the iris (mean 4.9 mm; range 4.5 to 5.0 mm). The mean deviation from the target diameter of the extracted capsule disks was 60 G 44 mm (range 4 to 146 mm) (Figure 6). In all eyes, the IOL was placed in the capsular bag and
Figure 3. A: Laser capsulotomy after trypan blue staining followed by homogenous OVD fill of the anterior chamber with incomplete cut from 5 to 7 o'clock in a Morgagnian cataract. B: Free capsulotomy after the dimpling-down maneuver with a blunt cannula attached to the OVD syringe. J CATARACT REFRACT SURG - VOL 40, JANUARY 2014
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Figure 4. Light microscopy overview of stained capsulotomies from intumescent cataracts with different sizes. Target diameter: A: 4.9 mm. B: 4.5 mm. C: 4.7 mm. D: 5.0 mm (ø Z diameter).
was well centered after OVD removal, with no cases of capsular bag distortion or zonular dehiscence. Figure 5 shows a high-magnification light microscopy (LM) image of the capsule edge. Different rounds of laser spots with different depth can be seen. All spots were nearly on the same line within 1 circular round because the laser treats from the posterior and focuses the laser pulses at different depths as the incisions progresses anteriorly through the capsule. The rounds deviated from one another, and the inner rounds were closer together. Most spots had trails that were directed toward the capsule center. The distance between the inner row and the outer row of laser pulses was approximately 116 mm. While docked to the laser, algorithms using the fullvolume OCT automatically verified and detected the anterior capsule in all 25 cases (Figure 1). In 15 eyes,
the posterior capsule could be visualized by the surgeon on the OCT cross-sectional images; in 3 of the 15 eyes, the posterior capsule was correctly automatically mapped by the system. DISCUSSION White cataracts are difficult to visualize during manual CCC because of the lack of red reflex. Also, they are susceptible to high intracapsular pressure, leading to the Argentinean flag sign and potential radial tears. Gavris et al.2 report the following incidence: failed capsulorhexis, less than 4%; posterior capsule rupture, less than 1%; and conversion to extracapsular cataract extraction, less than 4%. Different ways to achieve a safe manual capsulorhexis in white cataract cases (eg, use of OVDs or dyes) have been described.11 Other
Figure 5. Screenshots with different magnification of the capsulotomy edge after femtosecond laser–assisted treatment in an eye with high intracapsular pressure and capsule disk movement showing aberrant intracapsular laser shots.
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Figure 6. Deviation from target capsulotomy diameter in intumescent white cataracts.
approaches use high-frequency diathermy12,13 or a 2step CCC that can be enlarged after a central small CCC is created.14 However, to our knowledge, this is the first prospective trial of femtosecond laser–assisted cataract surgery in eyes with intumescent white cataract. A completely cut, well-centered, and well-sized capsulotomy that does not compromise the integrity of the lens capsule is the goal to successful case management and predictable results. In our study, we evaluated femtosecond laser–assisted capsulotomy in eyes with intumescent white cataract to further assess safety issues related to capsulotomy. These included size, completeness, and associated complications. Despite small adhesions in 11 of 25 eyes and 1 uncut region over 2 hours in 1 eye, all resulting capsular bag openings after the capsular leaves were removed showed a curvilinear continuous edge. Two eyes (8%) developed anterior tears without further difficulties. There were no complications directly associated with the laser that led to additional difficulties in these challenging cases. It remains unclear whether the 2 anterior radial tears were related to the use of the femtosecond laser or whether they were related to the changes in capsule integrity caused by the mature intumescent lens. Because both occurred during phacoemulsification, we propose they were a surgeon-related complication. Neither vitreous loss nor posterior capsule rupture occurred during surgery, and no visible signs of IOL decentration or tilt were detected during the 6-week follow-up. Performing a capsulotomy with a femtosecond laser in an eye with white intumescent cataract requires precautions due to initial ejection of liquefied lens material into the anterior chamber once capsule breakthrough occurs. For comparison, Figure 2, A, shows
a normal capsulotomy whereas Figure 2, B, shows the milky lens material visible under near-infrared video as the incision breaks through the capsule. A second potential effect of high intracapsular pressure is partial collapse of the anterior lens surface in the breakthrough area, leading to a movement of the capsular leaf under the current focus of the laser and resulting in uncut regions. Lateral movement of the anterior capsule due to raised tension to the opposite side may lead to incomplete cuts of the capsulotomy and laser beams applied more centrally than expected. Therefore, the speed, spot spacing, and order of pulse delivery within a pattern for laser capsulotomy are critical, as is how each manufacturer adjusts the capsulotomy for lens tilt. All anterior capsulotomy settings used were system defaults and similar to the settings used in a normal case except that the incision depth was increased from 600 mm to 1000 mm to ensure a complete cut in case the anterior capsule moved after initial breakthrough. The histopathology LM images correlated well with the observed movements of the anterior capsule during laser treatment. At the moment the capsular bag opened at 1 point, the entire capsule disk moved vertically and laterally to the opposite side. Thus, all laser spots had a small, centrally located trail. As seen, the movement can be approximately 150 mm, and the resulting tongues represent a vulnerable point for potential radial tears. Furthermore, the histopathology capsule images showed that the laser system was able to shoot several rounds during capsule movement. The software versions used during this period included a capsulotomy creation of approximately 3 seconds, a repetition rate less than 60 kHz, and interlaced patterns in which every other spot was skipped on the first round and then filled in during a subsequent round. Laser settings with a higher repetition rate and optimized interlacing might be able to cut the disk 360 degrees before this movement occurs. Despite expected scattering of near-infrared wavelength OCT (830 nm)10 in opaque tissue or a white cataract, the high dynamic range, good signal-tonoise ratio, and image-processing algorithms provided good visualization of the posterior capsule in 15 of the 25 eyes. Given this imaging success rate, a future study could assess the ability of the femtosecond laser (1030 nm) to penetrate the white cataract to achieve the necessary energy density to reach the threshold to cut. Because of difficulties in detecting the integrity of a posterior capsule comprised by a hyperdense nucleus, it is imperative to avoid laser application for lens fragmentation in these eyes without safe detection of posterior lenticular structures and the posterior capsule.
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The OCT images, even partial depth through the cataract, provided diagnostic information to prepare a surgical plan. For example, they showed volumes of potential liquefied cortex with black intralenticular spaces and showed highly convex surfaces indicating potential intracapsular pressure. Given the potential risks discussed and others, such as attachments due to capsule fibrosis, we recommend a cautious approach to confirming capsulotomy completeness called the dimple-down technique. Intraoperatively, the central downward cannula motion technique helps separate the incomplete cuts. Intraoperative visualization of uncut regions using trypan blue is helpful to complete and to pull out the capsule disk with a forceps in a safe manner. The incidence of complications (eg, radial capsule tears or Argentinean flag sign), seems to be significantly lower when a femtosecond laser is used to create the capsulotomy. Even so, the surgeon must be aware of the obstacles and difficulties in performing successful surgery in eyes with intumescent mature lenses with their high intralenticular pressure. Surgery in eyes with white cataract is always a challenge to the surgeon because unexpected events can happen at any time during surgery. It is imperative that the surgeon be aware of the various types of intumescent white cataracts with arising complications according to the underlying pathology. Brazitikos et al.15 established a 3-step grading system that uses ultrasonography to classify white intumescent cataracts according to their liquefaction and hardness. In conclusion, in these challenging mature cataract cases, if a surgeon has access to a suitable femtosecond laser platform, we recommend it be used to safely and precisely create the anterior capsulotomy, hence further increasing indications for the use of a femtosecond laser16–25 to assist in cataract surgery. We believe the femtosecond laser offers a technical advantage and may improve the safety of surgery in highrisk cases because the anterior capsulotomy can be successfully created with the laser, thereby avoiding the risks of a manual capsulorhexis. WHAT WAS KNOWN Femtosecond laser–assisted capsulotomy is precise and obtains a reproducible opening of the anterior capsule. WHAT THIS PAPER ADDS Performing the capsulotomy in white lenses with a femtosecond laser was possible and safe and helped avoid intraoperative capsule complications related to increased intracapsular pressure.
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REFERENCES 1. Vasavada A, Singh R, Desai J. Phacoemulsification of white mature cataracts. J Cataract Refract Surg 1998; 24:270–277 ^ ra ^us C, Gusho E, Kantor E. [Phacoemul2. Gavris M, Popa D, Ca sification in white cataract]. [Romanian]. Oftalmologia 2004; 48:81–87 3. Dick HB, Aliyeva SE, Hengerer F. Effect of trypan blue on the elasticity of the human anterior lens capsule. J Cataract Refract Surg 2008; 34:1367–1373 4. Hawlina M, Stunf S, Hvala A. Ultrastructure of anterior lens capsule of intumescent white cataract. Acta Ophthalmol 2011; 89:367–370. Available at: http://onlinelibrary.wiley.com/doi/10. 1111/j.1755-3768.2010.02102.x/pdf. Accessed October 4, 2013 5. Chylack LT Jr, Wolfe JK, Singer DM, Leske MC, Bullimore MA, Bailey IL, Friend J, McCarthy D, Wu S-Y; for the Longitudinal Study of Cataract Study Group. The Lens Opacities Classification System III. Arch Ophthalmol 1993; 111:831–836 6. Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB. Effect of femtosecond laser fragmentation on effective phacoemulsification time in cataract surgery. J Refract Surg 2012; 28:879–883 7. Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB. Effect of femtosecond laser fragmentation of the nucleus with different softening grid sizes on effective phaco time in cataract surgery. J Cataract Refract Surg 2012; 38:1888–1894 8. Talamo JH, Gooding P, Angeley D, Culbertson WW, Schuele G, Andersen D, Marcellino G, Essock-Burns E, Batlle J, Feliz R, Friedman NJ, Palanker D. Optical patient interface in femtosecond laser–assisted cataract surgery: contact corneal applanation versus liquid immersion. J Cataract Refract Surg 2013; 39:501–510 9. Schultz T, Conrad-Hengerer I, Hengerer FH, Dick HB. Intraocular pressure variation during femtosecond laser–assisted cataract surgery using a fluid-filled interface. J Cataract Refract Surg 2013; 39:22–27 10. Palanker DV, Blumenkranz MS, Andersen D, Wiltberger M, Marcellino G, Gooding P, Angeley D, Schuele G, Woodley B, Simoneau M, Friedman NJ, Seibel B, Batlle J, Feliz R, Talamo J, Culbertson W. Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography. Sci Trans Med 2010; 2:58–85. Available at: http://www.stanford. edu/wpalanker/publications/fs_laser_cataract.pdf. Accessed October 4, 2013 11. Figueiredo CG, Figueiredo J, Figueiredo GB. Brazilian technique for prevention of the Argentinean flag sign in white cataract. J Cataract Refract Surg 2012; 38:1531–1536 12. Findl O, Amon M. Anterior capsulotomy created by radiofrequency endodiathermy and continuous curvilinear posterior capsulorhexis in a patient with intumescent cataract and primary capsular fibrosis. J Cataract Refract Surg 1998; 24:870–871 €ffnung bei 13. Pham DT, Liekfeld A, Hartmann C. Kapselo intumeszenter Katarakt mit dem Hochfrequenz-DiathermieKapsulotom [Capsulotomy in intumescent cataract with the high frequency diathermy capsulotomy]. Klin Monatsbl Augenheilkd 1998; 212:29–31 14. Gimbel HV, Willerscheidt AB. What to do with limited view: the intumescent cataract. J Cataract Refract Surg 1993; 19:657–661 15. Brazitikos PD, Tsinopoulos IT, Papadopoulos NT, Fotiadis K, Stangos NT. Ultrasonographic classification and phacoemulsification of white senile cataracts. Ophthalmology 1999; 106:2178–2183 nitz K, Takacs A, Miha ltz K, Kova cs I, Knorz MC, Nagy ZZ. 16. Kra Femtosecond laser capsulotomy and manual continuous curvilinear capsulorhexis parameters and their effects on intraocular lens centration. J Refract Surg 2011; 27:558–563
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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 nitz K, Takacs AI, Miha ltz K, Kova cs I, Knorz MC. 18. Nagy ZZ, Kra Comparison of intraocular lens decentration parameters after femtosecond and manual capsulotomies. J Refract Surg 2011; 27:564–569 Kra ltz K, Knorz MC, Alio JL, Taka cs AI, nitz K, Kova cs I, 19. Miha Nagy ZZ. Internal aberrations and optical quality after femtosecond laser anterior capsulotomy in cataract surgery. J Refract Surg 2011; 27:711–716 nitz K, Takacs A, Filkorn T, Gergely R, Knorz MC. 20. Nagy ZZ, Kra Intraocular femtosecond laser use in traumatic cataracts following penetrating and blunt trauma. J Refract Surg 2012; 28:151–153 Filkorn T, Nagy ZZ. ltz K, Kova cs I, Taka cs A, 21. Ecsedy M, Miha Effect of femtosecond laser cataract surgery on the macula. J Refract Surg 2011; 27:717–722 22. Bali SJ, Hodge C, Lawless M, Roberts TV, Sutton G. Early experience with the femtosecond laser for cataract surgery. Ophthalmology 2012; 119:891–899
23. He L, Sheehy K, Culbertson W. Femtosecond laser-assisted cataract surgery. Curr Opin Ophthalmol 2011; 22:43–52 24. Friedman NJ, Palanker DV, Schuele G, Andersen D, Marcellino G, Seibel BS, Batlle J, Feliz R, Talamo JH, Blumenkranz MS, Culbertson WW. Femtosecond laser capsulotomy. J Cataract Refract Surg 2011; 37:1189–1198 25. Abell RG, Kerr NM, Vote BJ. Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology 2013; 120:942–948
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First author: Ina Conrad-Hengerer, MD Institute for Vision Science, Ruhr University Eye Clinic, Bochum, Germany
Femtosecond laser–assisted cataract surgery in intumescent white cataracts Ina Conrad-Hengerer, MD, Fritz H. Hengerer, MD, PhD, Stephanie C. Joachim, MD, Tim Schultz, MD, H. Burkhard Dick, MD, PhD
PURPOSE: To evaluate the feasibility and safety of femtosecond laser–assisted capsulotomy in eyes with intumescent white cataract. SETTING: Ruhr University Eye Clinic, Bochum, Germany. DESIGN: Prospective clinical trial. METHODS: After femtosecond laser–assisted capsulotomy (Catalys Precision system), phacoemulsification was performed using pulsed ultrasound energy and the effective phacoemulsification time was evaluated. The lenticular capsule disk was stained intraoperatively with trypan blue and pulled out using a microsurgical forceps for further analysis of form and shape. RESULTS: Twenty-five eyes were included in this trial. Automatic optical coherence tomography detection of the anterior capsule was performed successfully in all eyes. Radial anterior tears occurred in 2 eyes, an adherent tongue-like capsule adhesion in 9 eyes, and an incomplete capsulotomy button in 3 eyes. In all cases, the intraocular lens was centered and the implantation was uneventful. The mean deviation from the target diameter of the extracted capsule disks was 60 mm G 44 (SD). CONCLUSION: The use of the femtosecond laser–assisted system for capsulotomy in surgery for intumescent white cataract appears to be safe and technically feasible. Financial Disclosure: Dr. Dick is a member of the medical advisory board of Optimedica Corp. No other author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2014; 40:44–50 Q 2013 ASCRS and ESCRS
One of the most challenging situations in anterior segment surgery is the removal of an intumescent white cataract. A mature white cataract may have increased intracapsular pressure due to liquefaction of the cortex and a hard or brunescent nucleus underlying an anterior and/or posterior cortical opacity. The most difficult step of cataract surgery in hypermature intumescent cases is performing a safe continuous Submitted: June 4, 2013. Final revision submitted: August 9, 2013. Accepted: August 13, 2013. From the Institute for Vision Science (Conrad-Hengerer, Joachim, Schultz, Dick), Ruhr University Eye Clinic, Bochum, and the Goethe University Eye Clinic (Hengerer), Frankfurt, Germany. Corresponding author: Ina Conrad-Hengerer, MD, Institute for Vision Science, Ruhr University Eye Hospital, In der Schornau 23–25, 44892 Bochum, Germany. E-mail: ina.conrad-hengerer@ kk-bochum.de.
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curvilinear capsulorhexis (CCC) without further anterior capsule complications.1,2 Even after capsule staining with trypan blue to increase visualization and reduce the elasticity of the anterior capsule,3 puncture of the capsule can lead to uncontrollable extension of the opening, which is known as the Argentinean flag sign. The structural causes of tensile weakness were confirmed with ultrastructural analysis of the anterior capsule of intumescent cataract, showing no increase in thickness but extrusions of basement membrane filaments at the basement membrane–epithelial border.4 Given the surgical challenges of capsulorhexis in intumescent white cataracts, we assessed the feasibility and safety of femtosecond laser capsulotomy in these patients. PATIENTS AND METHODS In this study, patients with intumescent white cataract were scheduled for elective unilateral standard phacoemulsification without laser lens fragmentation and intraocular lens 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2013.08.044
FEMTOSECOND LASER–ASSISTED SURGERY FOR WHITE CATARACT
(IOL) implantation by the same surgeon (H.B.D.) from December 2011 to June 2012 at the Department of Ophthalmology, University of Bochum, Germany. The study received approval of the Ethics Committee, Ruhr University of Bochum, and all aspects of the Declaration of Helsinki were observed. All enrolled patients had a visually significant intumescent white cataract and were willing to volunteer for the prospective trial after giving written informed consent. The exclusion criteria included a history of serious coexisting ocular disease (eg, uncontrolled glaucoma, optic atrophy, or ocular tumors), relevant corneal opacities, age less than 22 years, and participation in another clinical study. The Lens Opacities Classification System III nuclear opalescence (NO) grading score5 was used. Preoperative NO was estimated by an independent physician using a BQ 900 slitlamp (Haag-Streit) at maximum illumination without light filtering. The IOL power calculations were performed using noncontact partial coherence laser interferometry (IOLMaster, Carl Zeiss Meditec AG) in the contralateral eye and ultrasound (US) biometry.6,7 Intraoperative measurements included the attachment of the anterior capsule, anterior capsule tears, posterior capsule ruptures, and the absolute and effective phacoemulsification times.
Surgical Technique The femtosecond laser treatment was applied before US phacoemulsification and IOL implantation. All patients were placed in a reclined chair and positioned supine beneath the system. The 2-piece Liquid Optics Interface8,9 of the Catalys Precision femtosecond laser system (Optimedica Corp.), which consists of a suction ring and a nonapplanating immersion lens, was engaged by the surgeon. The surgeon controlled the patient chair using video imaging for alignment. Once suction was confirmed, the system automatically measured the dimensions of the anterior chamber and the lens using 3-dimensional spectral-domain OCT, which identified the ocular surfaces and created laser exclusion zones. Standard safety zones contain a distance limit to the pupil margin of 500 mm to avoid accidental laser damage of the iris. The results were displayed to the surgeon for verification (Figure 1). At this point, the surgeon could also use the video graphic user interface to reposition and/ or redesign the capsulotomy.10 In this clinical trial, the following parameters were used: capsulotomy diameter between 4.5 mm and 5.0 mm, horizontal spot spacing of 5 mm, vertical spot spacing of 10 mm, pulse energy of 4 mJ, and incision depth of 1000 mm. Because of the known limited efficacy of the femtosecond laser in opaque white tissue, no lens fragmentation or softening patterns were used. Once the surgeon verified all relevant parameters, he began the selected treatment (Figure 2). All patients had small-incision phacoemulsification using topical anesthesia and a 2.75 mm wide clear corneal incision. The corneal incisions were not available on the laser system at the time of protocol development and institutional review board review (December 2011), so they were created manually. The 2-step clear corneal main incision was created at 12 o'clock using a 2.75 mm metal keratome (Slit Knife, 2.75 angled, Alcon Laboratories, Inc.). The single-plane side-port incisions were placed at 9 o'clock and 3 o'clock and made with a 1.2 mm metal keratome (Side-port knife,
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Figure 1. Three-dimensional spectral-domain OCT without (A) and with (B) detection-overlay of the anterior and posterior corneal surface as well as the anterior capsule. The posterior capsule is not detected because of the fluid milky lenticular content, with intralenticular spaces (black) representing high intracapsular pressure.
dual bevel, 1.2 angled, Alcon Laboratories, Inc.). Trypan blue (Vision Blue, Dutch Ophthalmic) was injected to stain the capsule while keeping the anterior chamber deep. Then, the first step was to instill sodium hyaluronate 1.0% (Healon) into the anterior chamber via the paracentesis to maintain the anterior chamber once the cannula was advanced to the opposite angle. The cannula was then moved to the middle of the lens capsule and pressed downward with the tip of the cannula at the center of the capsule. This downward motion indents the capsule disk, pulls it gently centrally, separates the free edge from the surrounding peripheral capsule, and confirms that there is a continuous 360-degree cut with a free flap (Figure 3). The anterior capsule disk was extracted in all cases using a Koch microforceps (Geuder AG) for further histopathologic evaluation. This procedure was followed by phacoemulsification using the stop-and-chop technique or bimanual aspiration only. Ultrasound phacoemulsification was performed using the same phacoemulsification machine (Stellaris, Bausch & Lomb). Without enlarging the corneal tunnel, a heparin-coated preloaded hydrophobic acrylic IOL (Polylens H10, Polytech Ophthalmologie GmbH) was injected into the capsular bag. After careful removal of the ophthalmic viscosurgical device (OVD) and watertight incisions were achieved, all eyes were covered with a patch. Standard topical ofloxacin and dexamethasone eyedrops were administered 4 times daily for the first week. Then, the ofloxacin was discontinued and the dexamethasone dosage was gradually decreased over 6 weeks.
Lens Capsule Analysis After careful removal, the lens capsule disks were placed in reaction tubes filled with fortified balanced salt solution (BSS, Alcon Laboratories, Inc.). They were mounted on glass
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Figure 2. Screenshot of the infrared camera during femtosecond laser capsulotomy in a normal case (A) and in an intumescent cataract (B) with high intracapsular pressure. Note the localized milky fluid leakage out of the lens into the anterior chamber.
slides and stained with 0.5% trypan blue (Sigma-Aldrich Co.). The stained capsules were rinsed with phosphatebuffered saline (Aesku.Diagnostics GmbH & Co. KG ) and fixed with Eukitt (Kindler GmbH) after a short drying period. Microscopic images were captured digitally using an Axiocam HRcCCD camera on a Zeiss Imager M1 microscope (Carl Zeiss Meditec AG). The diameters of the capsule disk samples were measured using Axiovision software (version 4.8, Carl Zeiss Meditec AG).
Outcome Measures The main outcome measures were accuracy of the capsulotomy, presence of adhesions, and incidence of anterior and posterior tears. Furthermore, the capsulotomy disk size and the histopathologic cut quality and texture were examined. The automatic detection capability of optical coherence tomography (OCT) imaging of the femtosecond laser system for the anterior and posterior capsule was noted.
Statistical Analysis All descriptive statistical analysis was performed using SPSS software (version 19.0, SPSS, Inc.). Continuous variables were described as mean, standard deviation (SD), median, minimum, and maximum values.
RESULTS The clinical trial enrolled 25 eyes (13 right [52%]). The mean age of the 15 men (60%) and 10 women (40%) was 69 years G 14 (SD). In 12 eyes, capsule tags occurred. In 3 eyes, the capsulotomy was not free and small adhesions could be clearly visualized using trypan blue staining before they were removed. Furthermore, in 9 eyes a tongue-like capsule adherence was observed intraoperatively at the rim of the capsulotomy (Figures 4 and 5). In 2 eyes, an anterior tear occurred during phacoemulsification; however, the liquefied lens material was successfully removed. No posterior extension or posterior capsule tears occurred. An incomplete cut from 5 to 7 o'clock was detected in a Morgagnian cataract. The target capsulotomy size was 5.0 mm; however, the final programmed diameter was slightly smaller in some cases based on pupil dilation and the 500 mm safety zone to the iris (mean 4.9 mm; range 4.5 to 5.0 mm). The mean deviation from the target diameter of the extracted capsule disks was 60 G 44 mm (range 4 to 146 mm) (Figure 6). In all eyes, the IOL was placed in the capsular bag and
Figure 3. A: Laser capsulotomy after trypan blue staining followed by homogenous OVD fill of the anterior chamber with incomplete cut from 5 to 7 o'clock in a Morgagnian cataract. B: Free capsulotomy after the dimpling-down maneuver with a blunt cannula attached to the OVD syringe. J CATARACT REFRACT SURG - VOL 40, JANUARY 2014
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Figure 4. Light microscopy overview of stained capsulotomies from intumescent cataracts with different sizes. Target diameter: A: 4.9 mm. B: 4.5 mm. C: 4.7 mm. D: 5.0 mm (ø Z diameter).
was well centered after OVD removal, with no cases of capsular bag distortion or zonular dehiscence. Figure 5 shows a high-magnification light microscopy (LM) image of the capsule edge. Different rounds of laser spots with different depth can be seen. All spots were nearly on the same line within 1 circular round because the laser treats from the posterior and focuses the laser pulses at different depths as the incisions progresses anteriorly through the capsule. The rounds deviated from one another, and the inner rounds were closer together. Most spots had trails that were directed toward the capsule center. The distance between the inner row and the outer row of laser pulses was approximately 116 mm. While docked to the laser, algorithms using the fullvolume OCT automatically verified and detected the anterior capsule in all 25 cases (Figure 1). In 15 eyes,
the posterior capsule could be visualized by the surgeon on the OCT cross-sectional images; in 3 of the 15 eyes, the posterior capsule was correctly automatically mapped by the system. DISCUSSION White cataracts are difficult to visualize during manual CCC because of the lack of red reflex. Also, they are susceptible to high intracapsular pressure, leading to the Argentinean flag sign and potential radial tears. Gavris et al.2 report the following incidence: failed capsulorhexis, less than 4%; posterior capsule rupture, less than 1%; and conversion to extracapsular cataract extraction, less than 4%. Different ways to achieve a safe manual capsulorhexis in white cataract cases (eg, use of OVDs or dyes) have been described.11 Other
Figure 5. Screenshots with different magnification of the capsulotomy edge after femtosecond laser–assisted treatment in an eye with high intracapsular pressure and capsule disk movement showing aberrant intracapsular laser shots.
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Figure 6. Deviation from target capsulotomy diameter in intumescent white cataracts.
approaches use high-frequency diathermy12,13 or a 2step CCC that can be enlarged after a central small CCC is created.14 However, to our knowledge, this is the first prospective trial of femtosecond laser–assisted cataract surgery in eyes with intumescent white cataract. A completely cut, well-centered, and well-sized capsulotomy that does not compromise the integrity of the lens capsule is the goal to successful case management and predictable results. In our study, we evaluated femtosecond laser–assisted capsulotomy in eyes with intumescent white cataract to further assess safety issues related to capsulotomy. These included size, completeness, and associated complications. Despite small adhesions in 11 of 25 eyes and 1 uncut region over 2 hours in 1 eye, all resulting capsular bag openings after the capsular leaves were removed showed a curvilinear continuous edge. Two eyes (8%) developed anterior tears without further difficulties. There were no complications directly associated with the laser that led to additional difficulties in these challenging cases. It remains unclear whether the 2 anterior radial tears were related to the use of the femtosecond laser or whether they were related to the changes in capsule integrity caused by the mature intumescent lens. Because both occurred during phacoemulsification, we propose they were a surgeon-related complication. Neither vitreous loss nor posterior capsule rupture occurred during surgery, and no visible signs of IOL decentration or tilt were detected during the 6-week follow-up. Performing a capsulotomy with a femtosecond laser in an eye with white intumescent cataract requires precautions due to initial ejection of liquefied lens material into the anterior chamber once capsule breakthrough occurs. For comparison, Figure 2, A, shows
a normal capsulotomy whereas Figure 2, B, shows the milky lens material visible under near-infrared video as the incision breaks through the capsule. A second potential effect of high intracapsular pressure is partial collapse of the anterior lens surface in the breakthrough area, leading to a movement of the capsular leaf under the current focus of the laser and resulting in uncut regions. Lateral movement of the anterior capsule due to raised tension to the opposite side may lead to incomplete cuts of the capsulotomy and laser beams applied more centrally than expected. Therefore, the speed, spot spacing, and order of pulse delivery within a pattern for laser capsulotomy are critical, as is how each manufacturer adjusts the capsulotomy for lens tilt. All anterior capsulotomy settings used were system defaults and similar to the settings used in a normal case except that the incision depth was increased from 600 mm to 1000 mm to ensure a complete cut in case the anterior capsule moved after initial breakthrough. The histopathology LM images correlated well with the observed movements of the anterior capsule during laser treatment. At the moment the capsular bag opened at 1 point, the entire capsule disk moved vertically and laterally to the opposite side. Thus, all laser spots had a small, centrally located trail. As seen, the movement can be approximately 150 mm, and the resulting tongues represent a vulnerable point for potential radial tears. Furthermore, the histopathology capsule images showed that the laser system was able to shoot several rounds during capsule movement. The software versions used during this period included a capsulotomy creation of approximately 3 seconds, a repetition rate less than 60 kHz, and interlaced patterns in which every other spot was skipped on the first round and then filled in during a subsequent round. Laser settings with a higher repetition rate and optimized interlacing might be able to cut the disk 360 degrees before this movement occurs. Despite expected scattering of near-infrared wavelength OCT (830 nm)10 in opaque tissue or a white cataract, the high dynamic range, good signal-tonoise ratio, and image-processing algorithms provided good visualization of the posterior capsule in 15 of the 25 eyes. Given this imaging success rate, a future study could assess the ability of the femtosecond laser (1030 nm) to penetrate the white cataract to achieve the necessary energy density to reach the threshold to cut. Because of difficulties in detecting the integrity of a posterior capsule comprised by a hyperdense nucleus, it is imperative to avoid laser application for lens fragmentation in these eyes without safe detection of posterior lenticular structures and the posterior capsule.
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The OCT images, even partial depth through the cataract, provided diagnostic information to prepare a surgical plan. For example, they showed volumes of potential liquefied cortex with black intralenticular spaces and showed highly convex surfaces indicating potential intracapsular pressure. Given the potential risks discussed and others, such as attachments due to capsule fibrosis, we recommend a cautious approach to confirming capsulotomy completeness called the dimple-down technique. Intraoperatively, the central downward cannula motion technique helps separate the incomplete cuts. Intraoperative visualization of uncut regions using trypan blue is helpful to complete and to pull out the capsule disk with a forceps in a safe manner. The incidence of complications (eg, radial capsule tears or Argentinean flag sign), seems to be significantly lower when a femtosecond laser is used to create the capsulotomy. Even so, the surgeon must be aware of the obstacles and difficulties in performing successful surgery in eyes with intumescent mature lenses with their high intralenticular pressure. Surgery in eyes with white cataract is always a challenge to the surgeon because unexpected events can happen at any time during surgery. It is imperative that the surgeon be aware of the various types of intumescent white cataracts with arising complications according to the underlying pathology. Brazitikos et al.15 established a 3-step grading system that uses ultrasonography to classify white intumescent cataracts according to their liquefaction and hardness. In conclusion, in these challenging mature cataract cases, if a surgeon has access to a suitable femtosecond laser platform, we recommend it be used to safely and precisely create the anterior capsulotomy, hence further increasing indications for the use of a femtosecond laser16–25 to assist in cataract surgery. We believe the femtosecond laser offers a technical advantage and may improve the safety of surgery in highrisk cases because the anterior capsulotomy can be successfully created with the laser, thereby avoiding the risks of a manual capsulorhexis. WHAT WAS KNOWN Femtosecond laser–assisted capsulotomy is precise and obtains a reproducible opening of the anterior capsule. WHAT THIS PAPER ADDS Performing the capsulotomy in white lenses with a femtosecond laser was possible and safe and helped avoid intraoperative capsule complications related to increased intracapsular pressure.
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First author: Ina Conrad-Hengerer, MD Institute for Vision Science, Ruhr University Eye Clinic, Bochum, Germany
