Efficacy and Safety of a New Selective Laser Device to Create Anterior Capsulotomies in Cataract Patients

ARTICLE Efficacy and safety of a new selective laser device to create anterior capsulotomies in cataract patients

Pavel Stodulka, MD, PhD, FEBOS-CR, Richard Packard, MD, FRCS, FRCOphth, David Mordaunt, PhD

Purpose: To compare the efficacy and safety of anterior capsulot- Results: No intraoperative complications occurred in the laser group omy creation with a new selective laser device (CAPSULaser) with or the manual group. All capsulotomies in the laser group were free- those of manual capsulotomies. floating with no tags or tears. The mean capsulotomy diameter was 5.03 mm overall (range 4.8 to 5.2 mm, laser group; 4.4 to 5.8 mm, Setting: GEMINI Eye Clinic, Zlin, Czech Republic. manual group). In the laser group, all the capsulotomies were within 0.1 mm G 0.1 (SD) of the target. The circularity accuracy was greater than 99.0% G 1.0%; the mean centration of the Design: Prospective case series. capsulotomy in relation to the intraocular lens (IOL) was 0.1 G 0.1 mm. All parameters were statistically significant (P < .01). Methods: Patients were placed in cohorts based on age and The IOL–capsulotomy overlap was 360 degrees in all laser cases. cataract grade and randomly allocated to have laser capsulotomy or manual continuous curvilinear capsulorhexis (CCC). The Conclusions: Selective laser capsulotomy using a new proprie- anterior capsule was stained with microfiltered trypan blue tary trypan blue formulation was safe and effective in cataract sur- 0.4%. The anterior capsulotomy was created with the laser de- gery. The sizing, circularity, and centration of the laser capsulotomy vice focused on the anterior capsule through a custom patient were more accurate than those of the manual CCC, resulting in interface lens. Intraoperative video analysis with the use of an consistent 360-degree IOL coverage. intraocular ruler and postoperative examinations were used to J Cataract Refract Surg 2018; -:-–- Q 2018 ASCRS and ESCRS assess safety and efficacy (accuracy of capsulotomy size, circularity, centration). Online Video

ince the 18th century when Jacques Daviel ﬁrst per- effective lens position.8 This is particularly important formed extracapsular cataract surgery,1 the opening when multifocal and toric IOLs are implanted.9,10 Howev- S of the anterior capsule has been an inherent and in- er, femtosecond laser–assisted cataract surgery has associ- tegral part of the procedure. Techniques for capsulotomy ated caveats; that is, it requires a considerable investment have progressed from a crude tear to the current standard in capital and operating and maintenance costs.11 of continuous curvilinear capsulorhexis (CCC).2,3 In 2008, This study assessed the efficacy and safety of a capsulot- a new automated capsulotomy procedure was performed omy technique performed using the CAPSULaser selective using the femtosecond laser.4 For the first time, surgeons capsulotomy laser (EXCEL-LENS, Inc.). We compared the were able to create anterior capsulotomies that were results with those of manual CCCs. more accurately sized, consistently round, and better centered than manually created capsulotomies. A capsu- PATIENTS AND METHODS lotomy of accurate size, shape, and position helps ensure This prospective controlled interventional case series study was an 360-degree overlap of the intraocular lens (IOL) by the open prospective, controlled, interventional case series. Surgery capsulotomy. This reduces the risk for posterior capsule – was performed by 2 surgeons, one of whom was an author opacification5 7 and improves IOL centration and the (PS), between August and December 2016 at Gemini Clinic,

Submitted: December 22, 2017 | Final revision submitted: November 29, 2018 | Accepted: December 10, 2018 From Charles University (Stodulka), Prague, Czech Republic; Arnott Eye Associates (Packard), London, United Kingdom; EXCEL-LENS, Inc. (Mordaunt), Los Gatos, California, USA. Supported by EXCEL-LENS, Inc., Los Gatos California USA. Presented in part at the ASCRSASOA Annual Meeting, Washington, DC, USA, April 2018. Corresponding author: Richard Packard, MD, FRCS, FRCOphth, Arnott Eye Associates, 25 Queen Anne St, London W1G 9HT, United Kingdom. Email: eyequack@ vossnet.co.uk.

Q 2018 ASCRS and ESCRS 0886-3350/$ - see frontmatter Published by Elsevier Inc. https://doi.org/10.1016/j.jcrs.2018.12.012 2 SELECTIVE LASER DEVICE FOR ANTERIOR CAPSULOTOMIES

Figure 2. Patient interface lens in place on the cornea of a patient Figure 1. Selective laser device (inside red oval) attached to the having capsulotomy. The laser beam has already completed 270 operating microscope. A safety filter for the surgeon’s eye is placed of the 360 degrees of the treatment. in the microscope stack.

the Binocular Indirect Ophthalmomicroscope (BIOM, OCULUS Zlin, Czech Republic. The protocol of the study was approved by Surgical, Inc.) (Figure 1). It is located so that the fixation light is the local ethics committee and the national regulatory authority coaxial with the ocular view of the surgeon. (Czech State Institute for Drug Control). The clinical investigation The mechanism of action is selective laser absorption by a try- began after all relevant ethics committee and regulatory authority pan blue–dyed anterior capsule. The wavelength of the laser is in approvals (study reference 16EL01) were obtained. Written the red–orange range of the spectrum and absorbs trypan blue informed consent was obtained from each patient according to applied to the anterior capsule. If the dye were not present, the the tenets of the Declaration of Helsinki. laser light would pass through the capsule without interacting Patients were placed into cohorts based on age and cataract with it and rapidly extend to a large diffuse area on the retina. grade and then randomly allocated to have a selective laser capsu- The dye absorbs the laser energy, providing localized heating of lotomy (laser group) or a CCC (manual group) using a stratified 12 the capsule. This results in a phase change of the anterior collagen technique. Stratified randomization is a 2-stage procedure in from type IV to amorphous. The laser is programmed to inscribe a which patients who enter a clinical trial are first grouped into circle; the collagen phase change allows the formation of a roll at strata according to clinical features that may influence outcome the capsulotomy edge, which increases its elasticity, as shown by risk. Within each stratum, patients are then assigned to a treat- in vitro studies.A Preclinical surgical testing on pig eyes and ment according to separate randomization schedules. The goal cadaver eyes combined with thermocouple measurements and his- was to create homogeneous randomized populations for higher topathology have shown that selective laser capsulotomy has an statistical accuracy for comparisons of potential surgical complica- A 13 excellent ocular safety profile. The laser is compliant with the tions and non-inferiority. – relevant safety standards for use in ophthalmic surgery.15 17 Inclusion criteria were a clinically documented diagnosis of grade I to IV cataract according to the Lens Opacities Classification 14 System III, clear corneal media with no corneal disease or pathol- Preoperative Assessment ogy that might interfere with passage of the laser light, age 40 to 79 years, and an endothelial cell count of more than 2000 cells/ Preoperative examinations included uncorrected distance visual mm2. To be included, patients must have read, understood, and acuity (UDVA), corrected distance visual acuity (CDVA), auto- signed the informed consent and agree to be randomized to either mated and manifest refractions, anterior segment slitlamp evalua- treatment group. Standard exclusion criteria were used and tion, specular microscopy, intraocular pressure (IOP), optical included previous eye surgery, ocular comorbidities, and poorly biometry (IOLMaster, Carl Zeiss Meditec AG), fundus slitlamp dilating pupils. The study protocol stipulated 4 investigational evaluation, and optical coherence tomography. visits to ensure that the patients fulfilled the eligibility criteria. Surgical Technique Selective Laser Selective Laser Capsulotomy A lid speculum was inserted and hy- The CAPSULaser unit attaches to the underside of the optics of a droxypropyl methylcellulose placed on the cornea. A paracentesis standard operating microscope using the mounting location for was created. Next, an air bubble was injected followed administra- tion of a new proprietary trypan blue formulation (CAPSULBlue, EXCEL-LENS, Inc.). The dye was left for 15 seconds and then Table 1. Preoperative patient characteristics by group. washed out with a balanced salt solution. The chamber was filled Group with sodium hyaluronate 2.0% using a back-fill technique. Hy- droxypropyl methylcellulose was again placed on the cornea, Parameter Laser Manual and the patient interface lens was positioned. The aiming beam of the laser was turned on and focused using the guide from the Patients (n) 63 62 aiming beam. The fixation light was coaxial with the surgeon’s Sex (n) view, allowing most patients to fixate on the visual axis. Next Male 35 37 the surgeon assessed centration and determined the location of Female 28 25 the capsulotomy. The laser footswitch was depressed, which acti- Age (y) vated the laser to fire with 1 continuous beam (versus multiple Mean 61.8 62.2 pulses) for 1 second to create the capsulotomy (Figure 2)(Video Range 42, 79 42, 79 1, available at http://jcrsjournal.org). The capsulotomy disk was removed with a forceps, and the remainder of the cataract

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Table 2. Preoperative age range distribution by cataract grade and group. Grade 1 Grade 2 Grade 3

Age (Y) Laser Manual Laser Manual Laser Manual 70–79447755 60–69 5 5 12 12 3 3 50–59 10 10 7 7 0 0 40–49435500

surgery proceeded in typical fashion. All study-relevant laser set- the ruler placed in the capsule plane during surgery. The capsulot- tings were recorded. omy rim edge was defined by the reviewer, who identified at least Continuous Curvilinear Capsulorhexis A standard CCC was 40 points. The least-squares method was used to determine the created using a forceps under an ophthalmic viscosurgical device. best-fit circle (ie, circle diameter and center) for these identifica- Once the disk was removed with the forceps, the remainder of the tion points. – cataract surgery proceeded as normal. To be consistent with previous literature,18 21 circularity was assessed using 2 methods. First, it was calculated as follows: 4p Â area/perimeter2. Second, the least-squares approach was Postoperative Assessment used to determine the best-fit for an ellipse to the identified points, Follow-up visits were performed at 1 week and 1 month and with the reported circularity value being the ratio of the major to included the following: UDVA, CDVA, automated and manifest minor axes. In both methods, a reading of 100% circularity repre- refractions, slitlamp evaluation, IOP, and fundus evaluation by op- sented a perfect circle. tical coherence tomography. In addition, specular microscopy was A second video frame that clearly showed the capsulotomy edge repeated 1 month postoperatively. and the outside diameter of the IOL optic was selected. The cap- Efficacy and safety were assessed based on video recordings dur- sulotomy rim and the IOL perimeters were defined by the ing the surgery as well as postoperative examinations findings. reviewer, who identified at least 40 points for each. This image Adverse events and all observations were documented in elec- was calibrated with the outside diameter of the IOL. The least- tronic case report forms. An external research organization per- squares method was used to determine the best-fit circle for the formed site monitoring and controlled, verified, and analyzed capsulotomy and IOL outside diameter, determining that the the electronic case report forms. The full dataset was used for all best fit was the centration difference between the IOL and the reported results. capsulotomy.

Study Endpoints Statistical Analysis The following study endpoints were assessed: adverse events CONSORT guidelines22,23 were used to determine non-inferiority related to the treatment procedures, determined intraoperatively and superiority. Using SAS software (version 9.4, SAS Institute, and 1 week and 1 month postoperatively; surgical efficacy of the Inc.), an outside biostatistician calculated a minimum sample new trypan blue formulation as an intraocular dye for staining size in each study group of 55 patients to achieve statistical confi- the anterior capsule; efficacy of the selective laser in anterior cap- dence of at least 95% for non-inferiority, an assumed margin of sulotomy creation; and assessment of mechanical attachments non-inferiority of 0.05 mm, a test power of 0.8, and a dropout (tags or bridges) between the disk and the capsulotomy rim as rate of less than 10%. If non-inferiority was determined for selec- well as anterior tears. tive laser capsulotomy, superiority was tested. Other endpoints concerned efficacy and comprised the accuracy of the capsulotomy diameter size, circularity, and centration relative to the IOL. All measurable parameters and the analysis of RESULTS these measurements were assessed by independent reviewers. Three patients did not complete the study. Two patients The accuracy of the capsulotomy diameter, defined as the abso- failed to appear for postoperative visits in the study time- lute value of measured diameter subtracted from the intended frame despite receiving reminders. One patient died from target of 5.0 mm, was measured at the capsule plane using an intra- cardiac disease not related to the surgery. Table 1 shows ocular ruler after the capsulotomy disk had been removed and before phacoemulsification. Videorecording frames that showed the characteristics of the enrolled patients in the laser group the capsulotomy edge and intraocular ruler were selected and and manual group. The sex and age of the patients was analyzed for each capsulotomy. The image was calibrated with similar in the 2 groups.

Table 3. Preoperative and postoperative IOP by group. Laser Group Manual Group

Postop Postop

ValuePreop (n Z 63) 1 Wk (n Z 62) 1 Mo (n Z 61)Preop (n Z 62) 1 Wk (n Z 61) 1 Mo (n Z 61) Mean 16.3 15.1 14.6 16.1 15.0 14.9 SD 2.8 3.1 2.7 2.8 3.0 2.7 Median 16.0 15.0 14.5 16.0 15.0 14.5 Min 10.0 9.0 9.5 9.5 9.0 9.5 Max 25.0 24.0 20.0 24.0 22.5 22.5

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preoperatively to 1 month postoperatively was À0.3 logarithm of the minimum angle of resolution G 0.1 (SD) in both groups. This shows the non-inferiority of selective laser capsulotomy compared with CCC, with a non-inferiority margin of 0.1 logMAR (P ! .05). The mean endothelial cell loss between preoperatively and 1-month postoperatively was 11% G 5% in the laser group and 10% G 6% in the manual group. This shows the non-inferiority of selective laser capsulotomy compared with CCC, with a non-inferiority margin of 2% (P ! .05).

Efficacy In the laser group, all anterior capsules were uniformly Figure 3. Distribution of cumulative CDVA in laser group (red datapoints) and manual group (blue datapoints). The solid lines represent stained to an intense blue with a single application of the the 1-month postoperative data, and the dashed lines represent the trypan blue. All capsulotomies in this group were free- preoperative data (CDVA Z corrected distance visual acuity; floating with no mechanical attachments (tags or bridges) logMAR Z logarithm of the minimum angle of resolution). between the disk and the capsulotomy rim. No anterior or posterior tears occurred. Capsulotomy Diameter Figure 4 shows the difference in Table 2 shows the patient distribution by age range and capsulotomy diameters between the laser group and the cataract grade in both groups. The only between-group dif- manual group. The means were close to the intended diam- ferences was the number of patients in the 40- to 49-year eter of 5.0 mm in both groups. However, the precision of the age range with grade I cataract; 1 of the patients in this cate- distribution was greater in the laser group than in the gory was not eligible based on the exclusion criteria and was manual group, with a standard deviation of 0.09 mm and removed from the study. 0.31 mm, respectively. The diameter was within G0.1 mm of the target in 54 cases (86%) in the laser group Safety and in 27 cases (44%) in the manual group. The capsuloto- There were no capsulotomyor cataract surgery–related my diameter was within G0.4 mm in the range from 4.8 to adverse events. No eye had flare, epithelial staining or 5.2 mm in the laser group and within G1.4 mm in the range erosion, abnormal iris changes, a malpositioned IOL, cys- from 4.4 to 5.8 mm in the manual group. toid macular edema, or other abnormal signs. Figure 5 shows the frequency versus the diameter accu- Table 3 shows the preoperative and postoperative IOP; there racy in both groups. The 99% confidence interval (CI) were no significant differences in IOP values or the postoper- was 0.06 to 0.09 in the laser group and 0.17 to 0.30 mm ative decrease in IOP between the laser group and the manual in the manual group. Thus, the 99% CI for diameter accu- group. Statistical analysis of the change in IOP from preoper- racy was 30 mm and 130 mm, respectively. The complete CI atively to 1-month postoperatively showed non-inferiority of in the laser group was more favorable than the mean in the selective laser capsulotomy compared with CCC, with a manual group, showing that the diameter accuracy in the non-inferiority margin of 1.0 mm Hg (P ! .05). laser group was statistically significantly better (superior) Figure 3 shows the preoperative and 1-month postopera- than in manual group (P ! .01). tive cumulative CDVA data. The trend was similar between Capsulotomy Circularity Compared with the least- the laser group and manual group, with no statistically sig- squares approach, the first method of calculating capsulot- nificant differences. The mean improvement in CDVA from omy circularity (4p Â area/perimeter2) was more sensitive

Figure 4. Distribution of capsulotomy diameters (5.0 mm intended target) by group.

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Figure 5. Frequency plots versus diameter accuracy by group. The 99% CIs are represented by horizontal lines with arrows. The black line denotes the non-inferiority margin, and all CIs to the right of the line denote the region of non-inferiority (CI Z confidence interval).

to the smoothness of the edge and number of points used to smaller than the IOL optic and the IOL edge could not identify the edge but was relatively insensitive to the overall clearly be observed. Less miosis occurred and the pupils capsulotomy shape. Both groups had a high degree of circu- were more dilated in the laser group, and centration was larity (99.9% laser group; 98.5% manual group). The ratio measured in all patients. Centration of the capsulotomy of major axis to minor axis of the best-fit ellipse method was good in both groups, with all laser capsulotomies was sensitive to the overall capsulotomy shape; thus, this ra- centered less than 0.15 mm from the IOL center. In 3 cases tio was used as the measure of circularity accuracy; the in the manual group, the capsulotomy was more than mean was 99.2% in the laser group and 98.1% in the manual 0.4 mm from the IOL center, with the highest decentration group. being 0.78 mm. The laser and manual groups are character- The distribution of circularity accuracy was close to the ized by a mean and 99% confidence interval of 0.06 G 0.01 target in both groups (Figure 6). 55 cases (88%) in the laser and 0.10 G 0.07mm, respectively. The centration accuracy group and 21 cases (34%) in the manual group were within in the laser group was statistically significantly better (supe- 99% or more of circularity. The capsulotomy circularity ac- rior) than in the manual group (P ! .01). curacy (ratio of major to minor axes) in the laser group was Figure 8 (left) shows ideal centration on the pupil and 97% or better; the circularity accuracy in the manual group IOL position, with complete 360-degree capsulotomy was 94% or better. coverage of the IOL. In this case, the selective laser capsu- The 99% CI was 99.1% to 99.4% in the laser group and lotomy has a 5.0 mm diameter and 99.5% circularity and 97.7% to 98.4% in the manual group. The circularity accu- is decentered by 0.02 mm in relation to the IOL. Figure 8 racy in the laser group was statistically significantly better (right) shows major misalignment of capsulotomy in regard (superior) than in the manual group (P ! .01). to the pupil and IOL center, with incomplete 360-degree coverage. This example, an outlier in the manual group, is Capsulotomy Centration characterized by a 5.4 mm diameter, 97.2%, circularity, Figure 7 shows the capsulotomy centration relative to the and 0.8 mm decentration from the IOL. The IOL is not in IOL center. This could be measured only in approximately total alignment with the pupil center, as seen by the haptics 50% of cases in the manual group because the pupil was that center the IOL on the capsule bag equator, which is not

Figure 6. Capsulotomy circularity accuracy by group. The horizontal lines with arrows represent the 99% confidence intervals.

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a trend indicating that increased precision of these 3 factors would increase the rate of 360-degree coverage of the IOL by the capsulotomy. It has been shown clinically that incomplete 360-degree coverage of the IOL by the capsulotomy increases the likelihood of IOL tilting and malposition- – ing and the early-onset of posterior capsule opacification.5 7,18–21 Nagy et al.19 reported incomplete IOL coverage in 11% of cases and 28% of cases in a femtosecond laser–assisted cataract surgery group and a CCC group, respectively. A 28% Figure 7. Deviation from centration by group. The horizontal lines incomplete IOL coverage rate for CCC is high for modern with arrows represent the 99% confidence intervals. uncomplicated cataract surgery. This implies a correlation between capsulotomy precision and 360-degree IOL circular. In all cases in the laser group and 56 cases (91%) in coverage. It also suggests that a precise capsulotomy diam- the manual group, the capsulotomy edge covered the IOL eter is not the only factor and that accuracy in circularity for 360 degrees. and centration are also important to achieving complete 360-degree IOL coverage. DISCUSSION Good centration on the visual axis is especially critical in In recent years, technologies for creating more accurate multifocal IOL and toric IOL implantation because small capsulotomies than obtained with the CCC method have amounts of decentration and tilt degrade image quality. been developed; these include the use of femtosecond la- Well-centered capsulotomies and IOLs might also lead to sers4,19 and of precision pulse capsulotomy systems.24,25 better predictability of the effective lens position8; however, The present clinical study determined that capsulotomy this does not necessarily improve visual outcomes.26 Intra- diameter, circularity, and centration were statistically ocular lens manufacturers are starting to produce IOLs that more precise when selective laser capsulotomy was used take advantage of accurately sized and circular capsuloto- than when manual CCC was performed. It also shows the mies for capsulotomy capture of the IOL optic. The precise value of homogeneous recruitment and randomized alloca- centration of selective laser capsulotomies on the visual axis tion in better balancing baseline variables between a study will be important with these emerging designs. group and a control group. The selective laser capsulotomy was safe, with no capsulotomy- or cataract surgery–related adverse events. All capsulotomies in the laser group were free floating with no WHAT WAS KNOWN mechanical attachments (tags or bridges) between the disk and capsulotomy rim. Furthermore, no anterior or Trypan blue can be used to stain the anterior capsule without adverse effects. posterior capsule tears occurred. Moreover, the clinical out- Accurately sized capsulotomies covering the intraocular lens comes of the selective laser capsulotomy and CCC tech- (IOL) edge lead to less posterior capsule opacification. niques were similar, with no statistically significant Good centration is particularly important with advanced- differences in the UDVA, CDVA, IOP, endothelial cell technology IOLs. count, or related slitlamp and optical coherence tomogra- WHAT THIS PAPER ADDS phy examination findings. We recognize that the best way to assess the endothelial cell count is in a contralateral study The use of a new trypan blue dye to stain the anterior capsule used in conjunction with a new laser for capsulot- with at least 3 months of follow-up, and we are planning omies was safe and effective. such a study. The laser provided more accurate capsulotomy sizing, The overall precision of the capsulotomy diameter size, circularity, and centration than manually created continuous circularity, and centration was significantly better in the curvilinear capsulotomies. laser group than in the manual group (P ! .01). We saw

Figure 8. Representative capsulotomies in laser group (left) and manual group (right). The gray dots represent the capsulotomy edge, and the blue circle represents the best fit of the dots. The green circle represents the outline of the IOL body, and the red circle denotes the pupil center.

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In conclusion, this 125-patient clinical study found that 17. International Organization for Standardization. Ophthalmic Instruments – Fundamental Requirements and Test Methods – Part 2: Light Hazard Pro- selective laser capsulotomy and the new trypan blue formu- tection. Geneva, Switzerland, ISO, 2007, 2007; 15004-2 lation were safe and effective. No cataract surgery–related 18. Kranitz K, Takacs A, Mihaltz K, Kovacs I, Knorz MC, Nagy ZZ. Femtosecond adverse events occurred. All laser capsulotomies were free laser capsulotomy and manual continuous curvilinear capsulorrhexis parameters and their effects on intraocular lens centration. J Refract Surg floating, and no anterior or posterior tears occurred. 2011; 27:558–563 19. Nagy ZZ, Kranitz K, Takacs AI, Mihaltz K, Kovacs I, Knorz MC. Comparison of intraocular lens decentration parameters after femtosecond and manual REFERENCES capsulotomies. J Refract Surg 2011; 27:564–569 1. Daviel J. 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