SPECIAL ARTICLE A Cautionary Tale of Innovation in

George O. Waring III, MD, FRCOphth

Hyperopia is difficult to treat surgically. Nearly a dozen techniques strive toward safe, effective outcomes. All techniques are bedeviled by 3 challenges: (1) the need for accurate centration over the pupil of a steeper central optical zone approximately 5 mm in diameter, (2) the potential de- creased visual acuity caused by image minification,1,2 and (3) the creation of corneal contours with physiologic characteristics able to minimize optical aberrations and regression of initial refractive effect. Excimer laser photorefractive keratec- Three other methods for surgical cor- tomy3 and laser in situ keratomileusis rection of hyperopia have experienced (LASIK)4 for hyperopia are being devel- transient popularity until the high rate of oped with ongoing changes in ablation al- complications and lack of predictability gorithms. Thermal keratoplasty with a caused them to slink quietly away: hot- pulsed holmium:YAG laser has been needle thermal keratoplasty, which pro- plagued by marked regression of effect duced focal corneal necrosis and an un- when attempting to treat more than ap- stable refraction; hexagonal keratotomy, proximately +1.00 diopter (D) of hyper- which commonly produced irregular astig- opia.5,6 An infrared continuous-wave di- matism; and hyperopic automated lamel- ode laser (wavelength of 1.9 µm) is also lar keratoplasty (also known as H-ALK; being studied in clinical trials.7 Plus- more properly, deep lamellar keratotomy power phakic intraocular lenses face the for hyperopia), which produced progres- design challenge of being placed in hy- sive corneal ectasia in some eyes. peropic eyes that often have shallower an- terior chambers and less surgical space for THE LIMITS OF KERATOMILEUSIS implantation than myopic eyes8; contin- Deep lamellar keratotomy for hyperopia ued design changes and careful clinical tri- (“hyperopic ALK”) attempts to create con- als will probably yield safe and useful pha- trolled steepening of the central cornea by kic intraocular lenses for hyperopia within cutting with a microkeratome a lamellar the next few years. Clear lens extraction disc that is approximately 75% of corneal for high hyperopia with placement of 1 or thickness. This disc is left in place with- 2 intraocular lenses in the capsular bag or out sutures. The remaining thinner pos- ciliary sulcus has successfully treated these terior cornea displaces forward with in- patients who otherwise have consider- creased curvature to reduce hyperopia. The able visual disability.9 Intracorneal lenses procedure was done from approximately have a 50-year history of unsuccessful 1993 to 1996 on an estimated 60 000 eyes. clinical trials in the treatment of hyper- 12 10 In 1998, Lyle and Jin reported 67 con- opia and aphakia, but new materials and secutive eyes treated with hyperopic ALK surgical techniques and designs, such as with a 67% follow-up at 1 year. They ob- radially placed intracorneal polymethyl served that although the procedure steep- methacrylate stents and keratophakia with ened the central cornea and improved un- new synthetic lenticules, keep future pos- corrected visual acuity, instability of sibilities interesting. Intracorneal lenses refraction ensued with a mean myopic shift with small diameter and high index of re- of 0.50 D between 3 months and 1 year fraction have been studied in a small num- and of 1.00 D between 1 and 2 years. In ber of eyes, but decreased quality of vi- addition, 26% of the eyes developed sion led to termination of the research 11 enough steepening and irregular astigma- without publication of results. tism to be dubbed “iatrogenic keratoco- From the Department of , Emory University School of Medicine, nus,” and 16.4% had enough ectasia to re- Atlanta, Ga. quire penetrating keratoplasty.

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©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 The concept of creating a con- timates the minimal thickness of the late viscoelastic and wound heal- trolled corneal ectasia in refractive bed for long-term stability to be 200 ing processes that occur over time. surgery is not new. Radial kera- to 250 µm. This figure is based on The distribution of the stress- totomy for myopia intends to pro- the observation that for some 30 bearing layers of the cornea has been duce a controlled ectasia in which years, cryolathe and nonfreeze ker- studied, but not definitively charac- the corneal steepening occurs para- atomileusis were done in normal terized. MacPhee and colleagues23 re- centrally with concomitant central corneas that had a presumed cen- ported that all corneal layers equally flattening13; hexagonal keratotomy tral thickness of approximately 500 bear stress. The finite element simu- for hyperopia attempted to create to 550 µm, by creating an approxi- lations of Hanna and colleagues22 central corneal steepening14; and hy- mately 300-µm thick disc that then suggested that more stress was borne peropic ALK, with a similar biome- received a refractive cut and was re- by the posterior layers than the an- chanical concept, aims to produce placed with sutures, leaving a cor- terior layers. Seiler and colleagues24 a controlled central steepening. The neal bed 200 to 250 µm thick. Car- demonstrated that Bowman layer it- “control” is determined by the bio- men Barraquer19 reported that of self does not contribute more biome- mechanical properties of the indi- 1606 eyes that received cryolathe chanical support to the cornea than vidual cornea and is set by the length myopic keratomileusis (with a disc does the cellular stroma. This theo- and depth of the incisions, whether thickness of approximately 300 µm) retical information supports the con- radial, hexagonal, or lamellar. A la- and were followed up for approxi- cept that lamellar keratotomy made mellar keratotomy is also done dur- mately 2 decades, 45 (2.8%) devel- too deeply in the cornea will pro- ing keratomileusis (including oped corneal ectasia. She also re- duce corneal ectasia. LASIK) to create a flap or disc that ported the changes in average The major reason that the mini- reveals the stroma for refractive cor- corneal power (and radius of cur- mal residual thickness required for rection. The changes in corneal vature) over time: before surgery, corneal stability after keratomileu- shape after radial, hexagonal, and la- 43.75 D (7.7 mm); at 30 days, 35.50 sis remains unknown is that there mellar keratotomy occur in 3 time D (9.5 mm); at 90 days, 36.75 D (9.2 has been no reliable way to mea- frames: (1) acutely, within hours, re- mm); at 3 to 12 months, 37.12 D (9.1 sure the thicknesses of individual sulting in a substantial—usually de- mm); at 5 years, 37.87 D ( 8.9 mm); corneal layers postoperatively. The sirable—change in refraction and at 10 years, 39.25 D (8.6 mm); and ultrasound biomicroscope that uses visual acuity; (2) short-term fluctua- at 21 years, 39.25 D (8.6 mm). The a 50-MHz transducer can give beau- tion, such as diurnal variation after causes for this mild progressive cor- tiful images of portions of the cor- radial keratotomy15; and (3) gradu- neal steepening of approximately 2 nea (4-mm wide), but the 20-µm ally over a few years, as occurs in D from 1 to 20 years after keratomi- precision of this system25 is insuffi- progressive ectasia after hyperopic leusis are unknown, but possibili- cient to adequately evaluate cor- ALK and in the hyperopic shift ties include weakened biomechani- neal refractive surgery. A newer that occurs after cal support in the corneal bed, digital 50-MHz high-frequency ul- with incisions that extend to the underlying disease such as undetec- trasound system described by Rein- limbus.16,17 ted keratoconus, variations in sur- stein and colleagues26 can resolve The use of lamellar kera- gical technique that created a thin- and measure the epithelium, the stro- totomy in hyperopic ALK and in ker- ner corneal bed than intended, mal component of the corneal flap, atomileusis raises a fundamental chronic trauma to the cornea such and the thickness of the residual stro- question about corneal biomechan- as chronic eye rubbing, and epithe- mal bed in keratomileusis with a ics: What is the minimal thickness lial hyperplasia. Unfortunately, there precision of 1.3 µm (Figure). These of the cornea that can preserve cor- is no published long-term fol- measurements may create a better neal shape for the lifetime of the pa- low-up on a consecutive series of understanding of the limits of pro- tient without development of pro- eyes with a thorough statistical cedures that remove corneal tissue gressive corneal steepening or frank analysis of changes in corneal cur- to change refractive shape, such as ectasia? No one knows. An unsu- vature after keratomileusis. photorefractive keratectomy and tured corneal disc or flap that is cre- Jose´ Barraquer20,21 stated that a LASIK. Such postoperative measure- ated during keratomileusis contrib- residual corneal thickness of 300 µm ments in human eyes are neces- utes minimally to the biomechanical should remain to prevent ectasia. sary, because we do not know at the strength of the cornea, because its Hanna and colleagues22 used finite time of surgery the actual thick- attachments to the limbus have been element modeling of the cornea to ness of the corneal flap or the severed. Thus, the corneal strength demonstrate that resection of a layer actual ablation depth within the and shape are determined by the bio- of cornea approximately 50% its stromal bed; manufacturers give mechanical properties of the re- thickness (250 µm, 7.5-mm diam- guidance to the surgeon as to the sidual corneal bed, which are prob- eter) doubled the stresses at the cen- predicted thickness of the corneal ably different for each individual. As ter of the inner surface of the cor- flap in LASIK based on the gap set Lyle and Jin12 demonstrated after hy- nea and created slight anterior in the microkeratome, but it is well peropic ALK and as Seiler et al18 have displacement of the bed. These simu- known that flap thickness can vary shown after LASIK, a bed approxi- lated changes were only acute, and greatly from one eye to another us- mately 150 µm thick will become ex- to date there is no mathematical ing the same instrument. Similarly, cessively steep. Current opinion es- model of the cornea that can simu- the excimer laser ablation rate of

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©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 Epithelium creasing the complications of poor Bowman Layer wound healing, including anterior Entrance displacement of central cornea, ex- Interface cessive scarring, and induced astig- Hinge matism. The modifications went

Temporal Nasal from initial intersecting hexagonal pattern to nonintersecting patterns and then to nonintersecting pat- Output from a digital 50-MHz high-frequency ultrasound system described by Reinstein and colleagues.26 terns with paracentral transverse in- The image demonstrates a B-scan through the horizontal plane of the left eye of a patient 2 months after cisions.14,33-35 Many of these changes laser in situ keratomileusis. The high resolution identifies individual surfaces including the epithelium, Bowman layer, and the lamellar interface. Measurements are not made from the image, but rather from occurred as the procedure was pro- digital signal processing of the raw ultrasound data to provide 1.3-µm pachymetric precision. By mulgated in commercially spon- scanning at multiple meridians, the residual stromal thickness can be measured 3-dimensionally. sored refractive keratotomy skills transfer courses with the enthusias- corneal stroma quoted by the manu- some investigators27,28 with high- tic endorsement of refractive sur- facturer (eg, 0.25 µm per pulse) also temperature probes to flatten kera- geons who had extensive clinical ex- varies because of conditions in the toconus that produced variable un- perience, such as Mendez,33 Jensen,34 laser, such as variation in the qual- stable changes in corneal shape, and and Casebeer and Phillips.35 Many ity of the optics in the delivery sys- from the common-sense observa- of the student ophthalmologists tem; in an individual cornea, such tion that thermal necrosis of the cor- failed to ask, “If the results re- as variation in hydration; and/or in neal stroma would be unlikely to cre- ported in the presentations are so the operating area during surgery, ate a reliably predictable change in good, why are the surgical tech- such as variation in the humidity and corneal shape and refraction.5,29 Hex- niques changing so much?” Hyper- temperature. Intraoperative mea- agonal keratotomy was used by Sato opic ALK was pulled along in the surement of flap and bed thickness and Akiyama in the 1940s with 6 to wake of automated lamellar kerato- by ultrasound probes is very inac- 9 overlapping incisions in the pos- plasty for myopia by incorporation curate because of the low fre- terior cornea30,31 to steepen the cen- in the Chiron-Casebeer lamellar re- quency of handheld probes (20 tral cornea of rabbits. The variable fractive surgery courses. The use of MHz), the location and positioning refractive results were accompa- the commercially created brand of the probe, and immediate changes nied by induction of large amounts name “automated lamellar kerato- that occur in stromal hydration on of astigmatism; the technique was plasty (ALK)” blurred the distinc- raising the flap. Therefore, only ac- abandoned. Advocates of hyper- tion between the techniques for curate postoperative measure- opic ALK could have benefited from myopia and hyperopia, which used ments of the thickness of indi- the early experience of Jose´ Bar- a common surgical instrument— vidual corneal layers coupled with raquer with keratomileusis,20,21 the microkeratome—but which measurements of corneal radius of which would have warned that a achieved their results through en- curvature, corneal shape, and ocu- 350- to 400-µm deep lamellar cut in tirely different mechanisms. lar refraction followed over time will the cornea would probably pro- The combined phenomena of define the residual thickness of the duce uncontrolled steepening with enthusiastic presentations by “pio- cornea needed for stability after la- progressive ectasia. neers” from “eye institutes”36 at oph- mellar refractive corneal surgery. The second common error was thalmic meetings and happy reports the propagation of these 3 proce- of “breakthroughs” by uncritical staff FLAWED METHODS OF dures among ophthalmologists on writers in ophthalmic and lay news- EVALUATING NEW SURGICAL the basis of informal experience, papers propelled the 3 procedures TECHNIQUES newspaper communication, and au- forward. The common cliche´s, “In thoritative endorsement by promi- my experience,” “I have done hun- The report of Lyle and Jin12 raises a nent surgeons. Hot-needle thermal dreds of cases,” and “My patients are broader question: How did hyper- keratoplasty emanated from extremely happy,” peppered the ora- opic ALK become transiently popu- in 1984, with powerful promulga- tory, often without thorough assess- lar? This procedure and 2 other tran- tion by Svyatoslav Fyodorov, MD, ment of clinical data. For example, siently popular procedures for the champion of modern refractive the following quotes were pub- hyperopia—hot-needle thermal keratotomy. Some surgeons who had lished in an ophthalmic newspaper keratoplasty and hexagonal kera- followed Fyodorov’s early lead in re- (Ocular Surgery News. August 1, totomy—spotlight 3 errors made fractive keratotomy surgery used the 1992) concerning hexagonal kera- commonly in the evaluation of new Russian-manufactured thermal kera- totomy: “We have not had a single surgical procedures. toplasty instrument in both labora- case of irregular astigmatism...not The first error affirms the ad- tory and human trials,29 informally a single patient who could not be re- age, “Those ignorant of history are reporting favorable results.32 Hex- fracted to 20/20...wehave quite a doomed to repeat it.” Those who agonal keratotomy reemerged from number of happy patients in our prac- pursued hot-needle thermal kerato- Mendez33 of Mexico in 1987. The tice.” “None of my patients have ex- plasty could have benefited both procedure quickly underwent a se- perienced irregular astigmatism.” from the unsuccessful experience of ries of modifications aimed at de- Ophthalmologists are “...complain-

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©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 ing about things that happened 10 hyperopic ALK in the peer-reviewed cally since 1963. A considerable num- years ago instead of being aware of literature42-44 is relieved somewhat by ber of articles rapidly appeared in the what is going on now.” Candid pre- the observations of Lyle and Jin,12 who peer-reviewed literature substantiat- sentation of complications was miss- recommended cessation of the use of ing the safety and effectiveness of ing, or sometimes the complica- the procedure. Unfortunately, this LASIK.49-51 tions were disguised under the rubric recommendation in 1998 arrived that the technique was for “ad- years after hyperopic ALK had disap- SUGGESTIONS FOR TESTING vanced surgeons.” The scenes at peared from clinical use. NEW SURGICAL TECHNIQUES meetings and courses resembled the fairy-tale emperor parading in his SOCIAL ENGINEERING These modern cautionary tales of new clothes; the voice of a lone child IN REFRACTIVE SURGERY new refractive surgical techniques revealed the emperor’s nakedness. In gone awry raise a serious question the case of hexagonal keratotomy, the Social engineering is a marketing for ophthalmic surgeons: How can lone voice came from Nordan and technique in which proponents of a new surgical techniques be devel- Maxwell, who reported in the news subject devise a strategy to over- oped and refined for general clini- media and letters to the editor37 that come a target group’s traditional cal use—or abandoned—without hexagonal keratotomy “has proven to aversion to an idea. It can be used creating the widespread clinical mor- be a failure” and called for a mora- for good cause, such as finding ways bidity that resulted from these 3 pro- torium on the procedure; their chal- to introduce birth control in tradi- cedures? The answer is easy, as I lenge and subsequent reports of com- tionally male-dominated societies have suggested elsewhere.52,53 plications38 led to the disappearance with overpopulation problems, or for 1. Maintain an attitude of pro- of hexagonal keratotomy from ac- the more dubious cause of creating fessional restraint that places the in- tive use. rapid profits by promulgating sales terest of the patient before the in- A third error occurred during of surgical equipment and adop- terest of the surgeon and that resists the clinical spread of these 3 tech- tion of new surgical techniques that the mindless rush to be the first phy- niques: there was a paucity of de- bypass professional and scientific sician to do the latest procedure on tailed reports of consecutive series safeguards. Commonly, a company the most patients for the greatest of eyes with a high percentage of fol- will create a “surgeon expert” who gain.54 low-up in the peer-reviewed lit- may trivialize the importance of sci- 2. Insist on a staged evaluation erature—or anywhere. Concern- entific work and the systematic ofnewtechniqueswithalimitednum- ing hot-needle thermal keratoplasty, evaluation of new techniques by the ber of eyes being treated and reported Neumann and colleagues29,32 gath- ophthalmic community and by for- in the peer-reviewed literature in the ered and published data from an in- mal prospective clinical trials. The earlier stages of development, with formal Russian series and then em- company and the expert create a se- laterexpansion,follow-up,andreport- barked on clinical trials to try to ries of courses, exploit enthusiastic ing of larger numbers.41,53 determine the optimal variables for articles in ophthalmic newspapers, 3. Disclose the weaknesses, the procedure, but the opening sen- and spread word-of-mouth hype. drawbacks, and complications of a tence of their final publication in a Many ophthalmic surgeons— procedure, in spite of attempts to con- non–peer-reviewed periodical re- including respected academics who ceal them by industry sponsors or sur- flected considerable bias: “Hyper- want to be in the forefront of refrac- geon progenitors, while extolling its opic thermokeratoplasty (HTK), a tive surgery—jump on the band- virtues and advantages, so that more recently developed procedure, may wagon, increasing sales of new in- impressionable colleagues will have offer the best combination of safety, struments and increasing the a balanced understanding. Evaluate predictability, stability, and cost ef- number of cases done with new tech- it—don’t sell it. fectiveness for correcting hyper- niques. The result is that a large 4. Avoid premature dissemina- opia.”32 Publications concerning amount of this innovative work is tion of evolving and unproven pro- hexagonal keratotomy by Neu- poorly documented, because the cedures so that student surgeons mann and McCarty,39 Grady,40 techniques and results are not re- do not operate on large numbers of Jensen,34 and Casebeer and Phil- ported in the peer-reviewed litera- patients using partially developed or lips35 presented useful clinical in- ture. This is a pattern that occurred inadequate techniques.55 formation from a cumulative group with hot-needle thermal kerato- 5. Invest the money, time, and of more than 400 eyes and con- plasty, hexagonal keratotomy for hy- energy to do simple prospective cluded that the technique was effec- peropia, and hyperopic ALK, to the trials: train office staff, ensure 90% tive and safe but required more detriment of many patients. Some or more patient follow-up, contract study; however, at no point did the have claimed that a similar path was with skilled individuals who can help authors call for or conduct a for- followed by LASIK, but I believe that compile and analyze the results, write mally structured clinical trial or sug- is not correct, because the early de- and publish an article that reports all gest a moratorium on the expansion scriptions of LASIK were scientific, cases and complications.56,57 of the surgery until more trial-and- were published in the peer-reviewed 6. Publish communications in error refinement and informal test- literature,45-48 and the technique was peer-reviewed journals—not just ing41 could define its safety and ef- based on the principles of keratomi- ophthalmic newspapers. All peer- ficacy. The paucity of articles on leusis, which had been practiced clini- reviewed journals publish letters to

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©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 the editor, brief reports, case stud- 13. Holladay JT, Waring GO. Optics and topography 34. Jensen RP. Hexagonal keratotomy: clinical expe- of radial keratotomy. In: Waring GO. Refractive rience in 483 eyes. Int Ophthalmol Clin. 1991;31: ies, and preliminary results—in ad- Keratotomy for Myopia and Astigmatism. St Louis, 69-73. dition to detailed original articles. Mo: Mosby–Year Book Inc; 1992:37-139. 35. Casebeer JC, Phillips SG. Hexagonal keratotomy: 7. Publish negative results and 14. Gilbert ML, Friedlander M, Granet N. Corneal steep- an historical review and assessment of 46 cases. ening in human eye bank eyes by combined hex- Ophthalmol Clin North Am. 1992;5:727-744. reasons why a technique should be or agonal and transverse keratotomy. Refract Cor- 36. Waring GO. The Hamburger Institute. J Refract has been abandoned, as wisely done neal Surg. 1990;6:126-130. Corneal Surg. 1994;10:495-497. 15. McDonnell PJ, Nizam A, Lynn MJ, Waring GO, 37. Nordan LT, Maxwell WA. Avoid both radial kera- by Lyle and Jin concerning hyperopic totomy with small optical zones and hexagonal 12 PERK Study Group. Morning-to-evening change ALK. This helps reduce repetition in refraction, corneal curvature and visual acuity keratotomy [letter]. Refract Corneal Surg. 1992; of the same problems in the future. In- 11 years after radial keratotomy in the Prospec- 8:331. deed, those who fail to heed prior mis- tive Evaluation of Radial Keratotomy Study. Oph- 38. Basuk WL, Zisman M, Waring GO, et al. Compli- thalmology. 1996;103:233-239. cations of hexagonal keratotomy. Am J Ophthal- takes are doomed to repeat them—to 16. Waring GO, Lynn MJ, McDonnell PJ, Prospective mol. 1994;117:37-49. the detriment of our patients and our Evaluation of Radial Keratotomy Study Group. Re- 39. Neumann AC, McCarty GR. Hexagonal kera- totomy for the correction of low hyperopia: pre- professional reputations. sults of the Prospective Evaluation of Radial Kera- totomy (PERK) Study 10 years after surgery. Arch liminary results of a prospective study. J Cata- ract Refract Surg. 1988;14:265-269. Ophthalmol. 1994;112:1298-1308. 40. Grady FJ. Hexagonal keratotomy for corneal steep- 17. Lindstrom RL. Minimally invasive radial kera- ening. Ophthalmic Surg. 1988;19:622-623. Accepted for publication April 22, totomy: mini-RK. J Cataract Refract Surg. 1995; 41. Waring GO. Development and evaluation of re- 1999. 21:27-34. fractive surgical procedures, 1: five stages in the 18. Seiler T, Koufala K, Richter G. Iatrogenic keratec- Reprints: George O. Waring III, continuum of development. J Refract Surg. 1987; tasia after laser in situ keratomileusis. J Refract MD, FACS, FRCOphth, Department 3:142-157. Surg. 1998;14:312-316. 42. Kezirian GM, Gremillion CM. Automated lamellar of Ophthalmology, Emory Univer- 19. Barraquer CC. Correction of ametropias by freez- keratoplasty for the correction of hyperopia. J Cata- sity School of Medicine, 1365 Clifton ing refractive lamellar surgery: freezing keratomi- ract Refract Surg. 1995;21:386-392. Rd, Atlanta, GA 30322 (e-mail: leusis. In: Pallikaris IG, Siganos DS, eds. LASIK. 43. Manche EE, Judge A, Maloney RK. Lamellar kera- Thorofare, NJ: SLACK Inc; 1998:13-30. toplasty for hyperopia. J Refract Surg. 1996;12: [email protected]). 20. Barraquer JI. Cirugia Refractiva de la Cornea. 42-49. Bogota, Colombia: Instituto Barraquer de Ame´- 44. Lyle WA, Jin GCJ. Initial results of automated la- ria; 1989:383. mellar keratoplasty for correction of myopia: one REFERENCES 21. Barraquer JI. Basis of refractive keratoplasty. Arch year follow-up. J Cataract Refract Surg. 1996;22: Soc Am Oftalmol Optom. 1967;6:383. 31-43. 22. Hanna K, Jouve F, Bercovier M, Waring GO. Com- 45. Palikaris J, Papatsanaki M, Stathi E, Frenschock 1. Applegate RA, Howland HC. 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