Intracorneal ring segments (ICRS) were used in the 1980s1 for low and moderate myopia correction, and anterior cornea curvature flattening occurred by placing ICRS on the stroma. Previous studies reported that it was a safe, effective, and stable method to correct low myopia.2 Currently, the method has been extended to various pathologies, such as keratoconus, pellucid marginal degeneration, and iatrogenic corneal ectasia.3 Three types of ICRS are available: Intacs (Addition Technology, Sunnyvale, CA), Ferrara (Mediphacos, Belo Horizonte, Brazil), and Keraring (Mediphacos). Classic ICRS channel creation by implanting the segments via mechanical dissection is currently being replaced by femtosecond lasers. In addition to being less annoying to the patient, the use of femtosecond lasers is faster and provides greater control of the depth, width, and centering of the tunnel, as well as increased accuracy. In addition, epithelial tissue changes are minimal and recovery after surgery is faster.4,5 Channel creation by both methods yields similar visual and refractive results. Nevertheless, increased intraoperative complications occurred with mechanical ICRS implantation.6,7
ICRS implantation involves intraoperative complications, such as incomplete tunnel creation, corneal surface perforation, or anterior chamber perforation. In the first case, the complication can be resolved by mechanical dissection. The perforation rates are low, which is one of the most serious complications.8,9 Another intraoperative complication is vacuum loss, which occurs during femtosecond laser suction; however, it is possible to recreate the same corneal plane and the intrastromal channel. Among postoperative complications, segment migration can occur, which may be due to an excessive ICRS width in a thin cornea. Coskunseven et al.8 and Mounir et al.10 reported a high ring migration rate. ICRS implantation near the incision implies a great risk of corneal melting, and ICRS should be explanted immediately in these cases.11 Another reason for explantation reported in the current literature is poor visual acuity or fluctuations in visual quality. The first to describe an explantation for this reason was Asbell et al.12 He noted glare, halos, and fluctuating vision. Other authors13–19 have also reported poor visual acuity as a reason for explantation.
One of the main goals of ICRS surgery is to treat keratoconus or ectasia after laser in situ keratomileusis (LASIK). The use of a permanent suture at the incision site and avoiding eye rubbing have been proposed.20 Infection risk is noted with ICRS implantation. Multiple microorganisms can cause this complication, and both bacteria and fungi can cause infectious keratitis. For example, Staphylococcus aureus21 appears in up to 25% of cases, followed by Pseudomonas species and Streptococcus pneumoniae, among others.22,23
Several factors have been detected in relation to the onset of this complication, such as previous traumas, use of contact lenses, or systemic diseases such as diabetes mellitus.24 The most efficient method to treat infectious keratitis after ICRS implantation is topical antibiotic therapy. Bourcier et al.25 reported that topical antibiotic therapy alone was sufficient to treat the infection. On the other hand, in some publications, ICRS explantation was considered as the first therapeutic option to treat this complication. Deep corneal neovascularization is another complication that can be caused by the implant and is not associated with the surgical wound. Treatment with topical corticoid agents and surgical removal of the ring may induce vessel regression.26
This systematic review reports intraoperative and postoperative ICRS complications and explantation rates among the available scientific literature.
Methods
This review is registered at the PROSPERO International prospective registry. The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations. PubMed, Web of Science, and Scopus databases were searched from January 1995 to June 2019. The keywords used were ring, rings, ICRS (intracorneal ring segments), segment, segments or Intacs, complication, explantation, explanted, retired, or removal. Experts identified and evaluated the articles selected according to inclusion and exclusion criteria. Two independent reviewers extracted and selected studies. Duplicate articles were assessed by the authors. Among the inclusion criteria were: (1) case reports, case series, chart analysis, and randomized controlled trials reporting intraoperative and postoperative complications in ICRS implantation; (2) ICRS explantation studies and the reasons; (3) there were no restrictions on publication type (conference abstract versus full article); and (4) abstracts were included only if they fulfilled our eligibility criteria and if no subsequent study had been published. Among the exclusion criteria were: (5) narrative reviews, systematic reviews, letters to the editor, and correspondence; (6) animal studies; and (7) non-English and non-indexed publications. The authors designed the tables to extract the study data.
Systematic review data were extracted according to study characteristics and main outcome measures. Among the first part, extracted data items included: (1) authors and publication year; (2) study design (case report or retrospective case series); (3) conflict of interest declaration (yes or no; which, if yes); (4) participant inclusion and exclusion criteria; (5) period of total patient follow-up from the first complication to its total resolution expressed in weeks; (6) percentage of male participants involved in the study; (7) number of participants and eyes involved in the study; (8) ICRS type, manual or femtosecond laser implantation, and ICRS brand and/or design; (9) number of segments per eye (ie, one, two, or both numbers were provided if one and two ICRS implantations were reported among different participants); and (10) mean participant age expressed in years. Among the outcome measures, the following data items were reported: (11) previous eye history, such as previous treatments, ocular pathologies, or eye surgeries; (12) intraoperative complications, and (13) postoperative complications with the percentage of total eyes in this study in brackets; (14) explantation rate; and (15) explantation reasons. Finally, (16) treatment used to resolve the complications was recorded. In this case, the treatment reported was the one that was ultimately effective. In-between unsuccessful treatments were avoided.
To determine the risk of bias in individual studies, two reviewers (M-JB-L and J-MS-G) with adequate reliability worked independently and blindly to create a summary chart (Table A, available in the online version of this article) based on the Quality Assessment Tool for Case Series Studies from the National Heart, Lung, and Blood Institute.27 For disputes between the two reviewers, a third unblinded reviewer (AL-M) resolved the issue. Questions included in the tool were: (1) Was the study question or objective clearly stated?; (2) Was the study population clearly and fully described, including a case definition?; (3) Were the cases consecutive?; (4) Were the participants comparable?; (5) Was the intervention clearly described?; (6) Were the outcome measures clearly defined, valid, reliable, and implemented consistently across all study participants?; (7) Was the length of follow-up adequate?; (8) Were the statistical methods well described?; and (9) Were the results well described? This analysis did not result in the elimination of any article. Articles with a high risk of bias had a lower weight for data synthesis. The primary summary measures used in this systematic review were incidence and percentage of complications and explantations among all included studies. Furthermore, the average changes in terms of visual acuity and mean keratometry were also reported. Finally, we also included ICRS design and implantation technique with more complications and common treatments used in complication resolution as summary measures.
Results
This systematic review study selection process is described by a flow diagram (Figure A, available in the online version of this article). A total of 39 studies published between 1995 and 2019 were included in this systematic review. Sixteen studies were case reports, 21 were case series studies, and only 2 were chart analysis works. Only 3 studies reported conflicts of interest.17,28,29 The inclusion criteria included participants with grade I, II, and III keratoconus; residual myopia after LASIK; ICRS explantation; keratitis infection; ectasia after LASIK; contact lens intolerance; ICRS migration; atopic keratoconus; or ICRS surgery simultaneously with cross-linking. Regarding exclusion criteria, most studies omitted ICRS implantation cases without complications. Other authors excluded studies for different reasons: corneal scarring,30 leucoma,31 keratitis,8,32 non-Intacs ICRS,15 manual ICRS implantation,17 or corneal hydrops10,28 in grade IV keratoconus. The postoperative follow-up ranged from 2 to 240 weeks. The mean follow-up for the reported studies was 56.9 weeks. This systematic review enrolled 1,946 participants. In total, 62.34% of these participants were male, and 2,590 total eyes were included. The mean age of participants was 33.45 years. Many of the studies reported that surgery was performed manually or with a femtosecond laser and the type of segment, but did not report the percentage of each type of surgery. Therefore, a quantitative analysis could not be performed using the studies. Detailed study characteristics are reported in Table B (available in the online version of this article).
Table 1 describes the complications caused by the ICRS and the explantation provided in the revised studies. In relation to the previous ocular history of the patients, we found 8 articles with ectasia after LASIK,14,15,19,22,29,30,33,34 6 articles with low and moderate myopia,12,14,18,23,24,35 2 articles with pellucid marginal degeneration,14,33 and only 1 article with keratoplasty.14 In addition, atopic asthma and blepharoconjunctivitis,36 lagophthalmos and dry eye,37 herpetic keratitis,38 and blepharitis39 were described in the ocular history.
Intraoperative complications were described in five publications: some epithelial damage at the incision site35; perforation of the anterior chamber (only 5% of the 20 eyes)20; difficult insertion in one case and intra-operative suction loss28; incomplete tunnel creation, misdirection of the ring segment, perforation into the anterior chamber, decentration of the ring segments, inverted implanted rings, broken ring segments, broken orifice of the ring10; and galvanometer lag error and endothelial perforation.8
Postoperative complications were described in most studies: migration, ring extrusion, corneal thinning, corneal melting, and type of infective keratitis (bacterial, Staphylococcus aureus, Streptococcus mitis, Staphylococcus epidermidis, annular herpetic, and Aspergillus fumigatus). These complications together with glare, halos, fluctuating vision, neovascularization, foreign body sensation, or pain account for 100% of the rings explanted in 50% of the articles. The percentage rate of explantation ranged from 0.5% up to 83.3%. If we analyze those articles with a high number of implantations8,10,28,33,40 (2,124 eyes), an explantation rate between 0% and 1.4% was obtained.
According to ICRS type reviewed, Ferrara and Keraring ICRS reported a 1% explantation rate, and Intacs reported a 19% explantation rate. Only 4 studies reported no explantation in the case.28,38,41,42 The most commonly used treatment was antibiotics in those articles in which it was described. Some articles did not report it, and two of the articles recommended suturing of the incision.17,42
Risk of bias assessment within the studies was grouped into three outcome levels: low (yes = 0 and 3),11,12,18,19,23,36–38,42–47 medium (yes = 4 to 6),14–16,22,24,29,33,35,39,40,41,48,49 and high (yes = 7 to 9).8,10,13,17,20,28,30–32,34,50,51
Discussion
Mechanical technique complications comprise anterior or posterior perforation by manual spreader, epithelial defects, decentration, and incision enlargement to the limbus or central cornea due to surgeon manipulation. Most cases of extrusion and final removal of ICRS were experimental in manual ICRS implantation. During ICRS implantation surgery, keratocyte activation52 and apoptosis were noted. Twa et al.53 demonstrated lipid formation and increased keratocyte density following ICRS implantation. Kugler et al.40 postulated that additional trauma to the incision and tunnel results in increased keratocyte apoptosis, major tissue degradation, and a subsequently increased number of complications, such as corneal melting. Femtosecond laser ICRS channel creation is less aggressive. Femtosecond laser treatment is associated with reduced complications for corneal melting. Corneal confocal microscopy has been used for assessment after manual54 and femtosecond laser55 ICRS implantation; however, to our knowledge, no studies have reported keratocyte activation scores in femtosecond laser versus manual techniques.
Nevertheless, the femtosecond laser introduced new complications to ICRS implantation. All of these complications were intraoperative, including incomplete channel creation, galvanometer lag error, and vacuum loss. Incomplete tunnel creation was solved by completing the channel using a mechanical separator; thus, complications of manual segment implantation were also noted. Coskunseven et al.8 proposed increasing the energy level of the femtosecond laser or reducing the space between spots. The false channel causes difficulty in implantation. As described by Jacob et al.,56 the situation can be overcome by removing the segment and turning it around so it is inserted in the opposite direction through the entry incision. It is then advanced using the second segment as an intra-channel instrument. When galvanometer error occurs, the surgical procedure must be suspended. During the second surgery, the same cone should be used. The tunnel channel depth must be 30 µm above the original tunnel.8 If an error occurs during incision formation, the cut should be continued with the knife edge. On the other hand, if vacuum loss occurs during incision, it is possible to create the vacuum again at the same conjunctival and corneal plane.8
One of the main reasons for the extrusion of the ICRS is segment migration. In this sense, the depth at which the segment is placed is key. Femtosecond laser tunnel creation is faster, easier, and more reproducible and offers accurate tunnel dimensions (width, diameter, and depth).57 This implies more control of intraoperative and postoperative complications.58 With mechanical dissectors, segment depth may be near the corneal surface, which increases late spontaneous ICRS extrusion risk.58 The femtosecond laser procedure generates more precise stromal separation compared with manual tunnel creation, which is based on the surgeon's skills. For both manual and femtosecond laser ICRS implantation, a suture can be placed in cases of segment migration that prevents the segment from migrating again.42
Of the 39 articles analyzed in this review, two did not report the type of implanted ring. Specifically, 16 Intacs (448 eyes), 13 Keraring or Ferrara Ring (1,804 eyes), and 8 cases with both (Intacs and Keraring) were reported without specifying how many of each type there were. The number of eyes with reported explantation is greater with Intacs (19%) compared with Keraring (1%) despite the fact than Intacs was implanted in a considerably smaller number of eyes. Most Intacs13,15–17,19,29 were explanted for low quality vision reasons.
Keraring and Ferrara Ring are more effective in the treatment of keratoconus compared with Intacs.59 Piñero et al.60 reported that astigmatism correction in ectatic cornea was more limited with Intacs, demonstrating that it increases the spherical corneal aberration. This finding implies a worsening of the visual quality, increasing the halos and glare. This notion is justified by the larger diameter of the Intacs, which induces minimal corneal central flattening.61
Among the limitations of this systematic review, the authors of the majority of cases only indicated the number of segments with complications and did not report the total number of segments implanted successfully. Thus, given that this information is not present in the published literature, it is not possible to establish the real prevalence of intraoperative and postoperative complications.
The femtosecond laser has reduced postoperative complications related to migration and corneal melting but has introduced new intraoperative complications, such as incomplete channel or vacuum loss. If patient selection is adequate and exhaustive, surgery planning can be implemented and intraoperative and postoperative complications will be minimized, representing the results of unpredictable surgery in most cases.
References
- Fleming JF, Reynolds AE, Kilmer L, Burris TE, Abbott RL, Schanzlin DJ. The intrastromal corneal ring: two cases in rabbits. J Refract Surg. 1987;3(6):227–232. doi:10.3928/1081-597X-19871101-07 [CrossRef]
- Schwartz AP, Tinio BO, Babayan A, Naikoo HN, Roberts B, Asbell PA. Intrastromal corneal ring implantation (360 degrees ring) for myopia: a 5-year follow-up. Eye Contact Lens. 2006;32(3):121–123. doi:10.1097/01.icl.0000178801.77766.c7 [CrossRef]16702864
- Piñero DP, Alio JL. Intracorneal ring segments in ectatic corneal disease: a review. Clin Exp Ophthalmol. 2010;38(2):154–167. doi:10.1111/j.1442-9071.2010.02197.x [CrossRef]20398105
- Ganesh S, Shetty R, D'Souza S, Ramachandran S, Kurian M. Intrastromal corneal ring segments for management of keratoconus. Indian J Ophthalmol. 2013;61(8):451–455. doi:10.4103/0301-4738.116065 [CrossRef]23925336
- Ratkay-Traub I, Ferincz IE, Juhasz T, Kurtz RM, Krueger RR. First clinical results with the femtosecond neodynium-glass laser in refractive surgery. J Refract Surg. 2003;19(2):94–103.12701713
- Rabinowitz YS, Li X, Ignacio TS, Maguen E. Intacs inserts using the femtosecond laser compared to the mechanical spreader in the treatment of keratoconus. J Refract Surg. 2006;22(8):764–771. doi:10.3928/1081-597X-20061001-06 [CrossRef]17061713
- Kubaloglu A, Sari ES, Cinar Y, et al. Comparison of mechanical and femtosecond laser tunnel creation for intrastromal corneal ring segment implantation in keratoconus: prospective randomized clinical trial. J Cataract Refract Surg. 2010;36(9):1556–1561. doi:10.1016/j.jcrs.2010.04.028 [CrossRef]20692570
- Coskunseven E, Kymionis GD, Tsiklis NS, et al. Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus. Acta Ophthalmol. 2011;89(1):54–57. doi:10.1111/j.1755-3768.2009.01605.x [CrossRef]
- Schanzlin DJ, Abbott RL, Asbell PA, et al. Two-year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmology. 2001;108(9):1688–1694. doi:10.1016/S0161-6420(01)00692-3 [CrossRef]11535474
- Mounir A, Radwan G, Farouk MM, Mostafa EM. Femtosecond-assisted intracorneal ring segment complications in keratoconus: from novelty to expertise. Clin Ophthalmol. 2018;12:957–964. doi:10.2147/OPTH.S166538 [CrossRef]29872254
- Cosar CB, Sridhar MS, Sener B. Late onset of deep corneal vascularization: a rare complication of intrastromal corneal ring segments for keratoconus. Eur J Ophthalmol. 2009;19(2):298–300. doi:10.1177/112067210901900222 [CrossRef]19253252
- Asbell PA, Uçakhan OO, Odrich M. Photorefractive keratectomy after intrastromal corneal ring segment explantation. Am J Ophthalmol. 1999;128(6):755–756. doi:10.1016/S0002-9394(99)00248-2 [CrossRef]10612513
- Alió JL, Piñero DP, Sögütlü E, Kubaloglu A. Implantation of new intracorneal ring segments after segment explantation for unsuccessful outcomes in eyes with keratoconus. J Cataract Refract Surg. 2010;36(8):1303–1310. doi:10.1016/j.jcrs.2010.02.017 [CrossRef]20656152
- Ferrer C, Alió JL, Montañés AU, et al. Causes of intrastromal corneal ring segment explantation: clinicopathologic correlation analysis. J Cataract Refract Surg. 2010;36(6):970–977. doi:10.1016/j.jcrs.2009.12.042 [CrossRef]20494769
- Bali SJ, Chan C, Hodge C, Sutton G. Intracorneal ring segment reimplantation in keratectasia. Asia Pac J Ophthalmol (Phila). 2012;1(6):327–330. doi:10.1097/APO.0b013e31826e1d30 [CrossRef]
- Yeung SN, Lichtinger A, Ku JYF, Kim P, Low SAW, Rootman DS. Intracorneal ring segment explantation after intracorneal ring segment implantation combined with same-day corneal collagen crosslinking in keratoconus. Cornea. 2013;32(12):1617–1620. doi:10.1097/ICO.0b013e3182a738ba [CrossRef]24071810
- Chhadva P, Yesilirmak N, Cabot F, Yoo SH. Intrastromal corneal ring segment explantation in patients with keratoconus: causes, technique, and outcomes. J Refract Surg. 2015;31(6):392–397. doi:10.3928/1081597X-20150521-05 [CrossRef]26046706
- Oatts JT, Savar L, Hwang DG. Late extrusion of intrastromal corneal ring segments: a report of two cases. Am J Ophthalmol Case Rep. 2017;8:67–70. doi:10.1016/j.ajoc.2017.10.004 [CrossRef]29260121
- Chan K, Hersh PS. Removal and repositioning of intracorneal ring segments: improving corneal topography and clinical outcomes in keratoconus and ectasia. Cornea. 2017;36(2):244–248. doi:10.1097/ICO.0000000000001075 [CrossRef]28060075
- Kanellopoulos AJ, Pe LH, Perry HD, Donnenfeld ED. Modified intracorneal ring segment implantations (INTACS) for the management of moderate to advanced keratoconus: efficacy and complications. Cornea. 2006;25(1):29–33. doi:10.1097/01.ico.0000167883.63266.60 [CrossRef]
- Levy J, Lifshitz T. Keratitis after implantation of intrastromal corneal ring segments (Intacs) aided by femtosecond laser for keratoconus correction: case report and description of the literature. Eur J Ophthalmol. 2010;20(4):780–784. doi:10.1177/112067211002000422 [CrossRef]20155711
- Shehadeh-Masha'our R, Modi N, Barbara A, Garzozi HJ. Keratitis after implantation of intrastromal corneal ring segments. J Cataract Refract Surg. 2004;30(8):1802–1804. doi:10.1016/j.jcrs.2004.01.034 [CrossRef]15313312
- Bourges J-L, Trong TT, Ellies P, Briat B, Renard G. Intrastromal corneal ring segments and corneal anterior stromal necrosis. J Cataract Refract Surg. 2003;29(6):1228–1230. doi:10.1016/S0886-3350(02)02036-9 [CrossRef]12842696
- Hofling-Lima AL, Branco BC, Romano AC, et al. Corneal infections after implantation of intracorneal ring segments. Cornea. 2004;23(6):547–549. doi:10.1097/01.ico.0000126434.95325.24 [CrossRef]15256990
- Bourcier T, Borderie V, Laroche L. Late bacterial keratitis after implantation of intrastromal corneal ring segments. J Cataract Refract Surg. 2003;29(2):407–409. doi:10.1016/S0886-3350(02)01484-0 [CrossRef]12648660
- Al-Torbak A, Al-Amri A, Wagoner MD. Deep corneal neovascularization after implantation with intrastromal corneal ring segments. Am J Ophthalmol. 2005;140(5):926–927. doi:10.1016/j.ajo.2005.05.020 [CrossRef]16310478
- National Heart, Lung, and Blood Institute (NHLBI). Study Quality Assessment Tools. https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools. Accessed December 15, 2018.
- Ibrahim O, Elmassry A, Said A, Abdalla M, El Hennawi H, Osman I. Combined femtosecond laser-assisted intracorneal ring segment implantation and corneal collagen cross-linking for correction of keratoconus. Clin Ophthalmol. 2016;10:521–526. doi:27041991
- Nguyen N, Gelles JD, Greenstein SA, Hersh PS. Incidence and associations of intracorneal ring segment explantation. J Cataract Refract Surg. 2019;45(2):153–158. doi:10.1016/j.jcrs.2018.09.021 [CrossRef]
- Carrasquillo KG, Rand J, Talamo JH. Intacs for keratoconus and post-LASIK ectasia: mechanical versus femtosecond laser-assisted channel creation. Cornea. 2007;26(8):956–962. doi:10.1097/ICO.0b013e31811dfa66 [CrossRef]17721296
- Zare MA, Hashemi H, Salari MR. Intracorneal ring segment implantation for the management of keratoconus: safety and efficacy. J Cataract Refract Surg. 2007;33(11):1886–1891. doi:10.1016/j.jcrs.2007.06.055 [CrossRef]17964393
- Abdelmassih Y, El-Khoury S, Dirani A, et al. Safety and efficacy of sequential intracorneal ring segment implantation and cross-linking in pediatric keratoconus. Am J Ophthalmol. 2017;178:51–57. doi:10.1016/j.ajo.2017.03.016 [CrossRef]28341606
- Mulet ME, Pérez-Santonja JJ, Ferrer C, Alió JL. Microbial keratitis after intrastromal corneal ring segment implantation. J Refract Surg. 2010;26(5):364–369. doi:10.3928/1081597X-20090617-06 [CrossRef]20506994
- Tabatabaei SA, Soleimani M, Mirghorbani M, Tafti ZF, Rahimi F. Microbial keratitis following intracorneal ring implantation. Clin Exp Optom. 2019;102(1):35–42. doi:10.1111/cxo.12810 [CrossRef]
- Güell JL, Velasco F, Sánchez SI, Gris O, Garcia-Rojas M. Intracorneal ring segments after laser in situ keratomileusis. J Refract Surg. 2004;20(4):349–355.15307397
- McAlister JC, Ardjomand N, Ilari L, Mengher LS, Gartry DS. Keratitis after intracorneal ring segment insertion for keratoconus. J Cataract Refract Surg. 2006;32(4):676–678. doi:10.1016/j.jcrs.2005.09.026 [CrossRef]16698494
- Galvis V, Tello A, Delgado J, Valencia F, Gómez AJ, Diaz LA. Late bacterial keratitis after intracorneal ring segments (Ferrara ring) insertion for keratoconus. Cornea. 2007;26(10):1282–1284. doi:10.1097/ICO.0b013e3181506142 [CrossRef]18043195
- Rayward O, Arriola-Villalobos P, Cuiña-Sardiña R, Diaz-Valle D, Benítez-Del-Castillo JM, García-Feijoo J. Annular herpetic keratitis after intracorneal ring segment implantation. Cornea. 2011;30(11):1286–1286. doi:10.1097/ICO.0b013e31821c9bb8 [CrossRef]21926564
- Neira W, Krootila K, Holopainen JM. Atopic dermatitis is a risk factor for intracorneal ring segment extrusion. Acta Ophthalmol. 2014;92(6):e491–e492. doi:10.1111/aos.12377 [CrossRef]24725421
- Kugler LJ, Hill S, Sztipanovits D, Boerman H, Swartz TS, Wang MX. Corneal melt of incisions overlying corneal ring segments: case series and literature review. Cornea. 2011;30(9):968–971. doi:10.1097/ICO.0b013e3182031ca0 [CrossRef]21448065
- López-Ferrando N, Medrano-Ruiloba JL. Intracorneal ring segment breaks following uneventful implantation. J Cataract Refract Surg. 2016;42(11):1684–1685. doi:10.1016/j.jcrs.2016.10.003 [CrossRef]27956298
- Jarade E, Dirani A, Fadlallah A, Antonios R, Cherfan G. New technique of intracorneal ring segments suturing after migration. J Refract Surg. 2013;29(10):722–724. doi:10.3928/1081597X-20130723-01 [CrossRef]23898946
- Quantock AJ, Kincaid MC, Schanzlin DJ. Stromal healing following explantation of an ICR (intrastromal corneal ring) from a nonfunctional human eye. Arch Ophthalmol. 1995;113(2):208–209. doi:10.1001/archopht.1995.01100020092036 [CrossRef]7864753
- Ibáñez-Alperte J, Pérez-García D, Cristóbal JA, Mateo AJ, Río BJ, Mínguez E. Keratitis after implantation of intrastromal corneal rings with spontaneous extrusion of the segment. Case Rep Ophthalmol. 2010;1(2):42–46. doi:10.1159/000320585 [CrossRef]21060771
- Chalasani R, Beltz J, Jhanji V, Vajpayee RB. Microbial keratitis following intracorneal ring segment implantation. Br J Ophthalmol. 2010;94(11):1541. doi:10.1136/bjo.2008.148619 [CrossRef]
- García de Oteyza G, Laiseca A, Sauvageot P, Álvarez de Toledo J. Methicillin-resistant Staphylococcus aureus acute keratitis after intracorneal ring segment implantation. Ophthalmol Ther. 2017;6(2):367–371. doi:10.1007/s40123-017-0103-9 [CrossRef]28808911
- Elbaz H, Werner L, Spiru B, Sekundo W. Spontaneous breakage of intracorneal ring segments (ICRS) 8 years after implantation. Saudi J Ophthalmol. 2018;32(4):341–345. doi:10.1016/j.sjopt.2018.03.005 [CrossRef]30581308
- Alió JL, Artola A, Ruiz-Moreno JM, Hassanein A, Galal A, Awadalla MA. Changes in keratoconic corneas after intracorneal ring segment explantation and reimplantation. Ophthalmology. 2004;111(4):747–751. doi:10.1016/j.ophtha.2003.08.024 [CrossRef]15051208
- Shihadeh WA. Aspergillus fumigatus keratitis following intracorneal ring segment implantation. BMC Ophthalmol. 2012;12(1):19. doi:10.1186/1471-2415-12-19 [CrossRef]22769849
- Kwitko S, Severo NS. Ferrara intracorneal ring segments for keratoconus. J Cataract Refract Surg. 2004;30(4):812–820. doi:10.1016/j.jcrs.2003.12.005 [CrossRef]15093643
- Iqbal M, Elmassry A, Tawfik A, et al. Analysis of the outcomes of combined cross-linking with intracorneal ring segment implantation for the treatment of pediatric keratoconus. Curr Eye Res. 2019;44(2):125–134. doi:10.1080/02713683.2018.1540706 [CrossRef]
- Twa MD, Ruckhofer J, Kash RL, Costello M, Schanzlin DJ. Histologic evaluation of corneal stroma in rabbits after intrastromal corneal ring implantation. Cornea. 2003;22(2):146–152. doi:10.1097/00003226-200303000-00014 [CrossRef]12605051
- Twa MD, Kash RL, Costello M, Schanzlin DJ. Morphologic characteristics of lamellar channel deposits in the human eye: a case report. Cornea. 2004;23(4):412–420. doi:10.1097/00003226-200405000-00021 [CrossRef]15097142
- Ruckhofer J, Böhnke M, Alzner E, Grabner G. Confocal microscopy after implantation of intrastromal corneal ring segments. Ophthalmology. 2000;107(12):2144–2151. doi:10.1016/S0161-6420(00)00387-0 [CrossRef]11097586
- Siatiri H, Jabbarvand M, Mohammadpour M, Mollazadeh A, Siatiri N, Mirmohammadsadeghi A. Confocal biomicroscopic changes of the corneal layers following femtosecond laser-assisted MyoRing implantation in keratoconus. J Curr Ophthalmol. 2016;29(3):182–188. doi:10.1016/j.joco.2016.11.004 [CrossRef]
- Jacob S, Nair V, Prakash G, Ashok Kumar D, Agarwal A, Agarwal A. Turnaround technique for intrastromal corneal ring implantation in eyes with false channel dissection. J Cataract Refract Surg. 2010;36(8):1253–1260. doi:10.1016/j.jcrs.2010.06.002 [CrossRef]20656146
- Monteiro T, Alfonso JF, Franqueira N, Faria-Correia F, Ambrósio R Jr, Madrid-Costa D. Predictability of tunnel depth for intrastromal corneal ring segments implantation between manual and femtosecond laser techniques. J Refract Surg. 2018;34(3):188–194. doi:10.3928/1081597X-20180108-01 [CrossRef]29522229
- Monteiro T, Alfonso JF, Freitas R, et al. Comparison of complication rates between manual and femtosecond laser-assisted techniques for intrastromal corneal ring segments implantation in keratoconus [published online ahead of print July 1, 2019]. Curr Eye Res. doi:10.1080/02713683.2019.1635165 [CrossRef]
- Hashemi H, Nabavi A, Bayat R, Mohebbi M. Additional intrastromal corneal ring segments in keratoconus. Cornea. 2018;37(5):574–579. doi:10.1097/ICO.0000000000001519 [CrossRef]29384806
- Piñero DP, Alió JL, El Kady B, Pascual I. Corneal aberrometric and refractive performance of 2 intrastromal corneal ring segment models in early and moderate ectatic disease. J Cataract Refract Surg. 2010;36(1):102–109. doi:10.1016/j.jcrs.2009.07.030 [CrossRef]20117712
- Kaya V, Utine CA, Karakus SH, Kavadarli I, Yilmaz ÖF. Refractive and visual outcomes after Intacs vs Ferrara intrastromal corneal ring segment implantation for keratoconus: a comparative study. J Refract Surg. 2011;27(12):907–912. doi:10.3928/1081597X-20110906-03 [CrossRef]21919431
Data Extraction for Complications and Explantations
| Author (Year) | Previous Eye History | Intraoperative Complications | Postoperative Complications | Explantation Yes/No (%) | Explantation Reason | Treatment Used |
|---|
| Quantock et al.43 (1995) | Nonfunctional eye or glaucoma | None | Crescentic iron line | Yes (100%) | Study protocol | NR |
| Asbell et al.12 (1999) | Myopia | None | Faint haze in stromal channel | Yes (100%) | Glare, halos, & fluctuating vision | Tobramycin/dexamethasone |
| Bourges et al.23 (2003) | Myopia | None | Lamellar channel deposits | Yes (100%) | Stromal thinning & extrusion | Bacitracin/polyvinyl alcohol |
| Shehadeh-Masha'our et al.22 (2004) | PLE | None | Bacterial keratitis | Yes (100%) | Staphylococcus | Cefamezin/gentamicin |
| Güell et al.35 (2004) | Residual myopia PL | Epithelial damage | Progressive stromal lysis | Yes (7.7%) | Progressive stromal lysis | NR |
| Alió et al.48 (2004) | KC | None | Migration (100%), partial extrusion (80%), moderate melting (80%), & corneal thinning (20%) | Yes (100%) | Segment migration & partial extrusion | NR |
| Hofling-Lima et al.24 (2004) | KC and low myopia | None | Infectious keratitis | Yes (62.5%) | Infectious keratitis | NR |
| Kwitko & Severo50 (2004) | KC | None | Ring decentration (3.9%), extrusion (19.6%), disciform keratitis (1.9%), & bacterial keratitis (1.9%) | Yes (3.9%) | Extrusion after trauma | NR |
| Kanellopoulos et al.20 (2006) | KC | AC perforation (5%) | Movement, exposure and corneal thinning (30%), CM, & infiltrate (5%) | Yes (35%) | Repeated exposure and/or corneal thinning | NR |
| McAlister et al.36 (2006) | KC, atopic asthma, & BC | None | White infiltrate & deposit formation | Yes (100%) | Infection keratitis | Dexamethasone chloramphenicol |
| Galvis et al.37 (2007) | KC, lagophthalmos, & dry eye | None | Staphylococcus aureus | Yes (100%) | Infection keratitis | Vancomycin, imipenem, amphotericin B, & moxifloxacin |
| Carrasquillo et al.30 (2007) | KC & PLE | None | Neovascularization & fungal infection | Yes (3%) | Herpes simplex keratitis | NR |
| Zare et al.31 (2007) | KC | None | ICRS exposure | Yes (13%) | Extrusion (13%) & bacterial keratitis (3%) | NR |
| Cosar et al.11 (2009) | KC | None | Neovascularization | Yes (100%) | Neovascularization | FML/ciprofloxacin |
| Ibáñez-Alperte et al.44 (2010) | NR | None | Corneal ulcer & hypopyon | Yes (100%) | Extrusion/bacterial keratitis | Vancomycin/ceftazidime |
| Alió et al.13 (2010) | Keratoconus | None | ICRS extrusion & vascularization | Yes (100%) | Extrusion (33%), VA (57%), & neovascularization (10%) | NR |
| Ferrer et al.14 (2010) | KC (79%), PLE (12%), PMD (5%), KP (2%), & myopia (2%) | None | ICRS migration, keratitis, CM, & corneal perforation | Yes (100%) | Extrusion (48%), VA (38%), keratitis (7%), CM (5%), & perforation (2%) | NR |
| Mulet et al.33 (2010) | KC (81%), irregular astigmatism (10%), PLE (5%), & PMD (4%) | None | Streptococcus mitis and aureus | Yes (1%) | Infection keratitis | Ceftazidime/amikacin, ofloxacin/vancomycin |
| Chalasani et al.45 (2010) | Keratoconus | None | Staphylococcus epidermidis | Yes (50%) | Infection keratitis | Vancomycin/tobramycin |
| Kugler et al.40 (2011) | NR | None | Corneal melt (1.4%) | Yes (1.4%) | Incision overlapping | BCL/steroids |
| Rayward et al.38 (2011) | RGP, CL, & herpetic keratitis | None | Annular herpetic keratitis | No (100%) | NA | Acyclovir/antibiotics |
| Coskunseven et al.8 (2011) | None | Incomplete channel (2.6%), galvanometer lag (0.6%), enodthelial perforation (0.6%), channel entrance (0.2%), & vacuum (0.2%) | ICRS migration (0.8%), corneal melting (0.2%), & corneal abscess (0.1%) | Yes (0.5%) | Corenal melting | Antibiotics |
| Shihadeh49 (2012) | CL intolerance | None | Aspergillus fumigatus | Yes (100%) | Microbiological infection | Gatifloxacin/itraconazole |
| Bali et al.15 (2012) | KC & PLE | None | Epithelial ingrowth | Yes (100%) | Poor VA/epithelial ingrowth | NR |
| Yeung et al.16 (2013) | NR | None | ICRS migration (33.3%) | Yes (83%) | Poor VA/ICRS migration | CXL |
| Jarade et al.42 (2013) | NR | None | ICRS migration | No (100%) | NA | Incision suturing |
| Neira et al.39 (2014) | Atopic dermatitis, AKC, blepharitis, & GPC | None | Corneal melting (100%) | Yes (100%) | Corneal melting | Topical steroids |
| Chhadva et al.17 (2015) | NR | None | VA (80%), overlapping, & VA (20%) | Yes (100%) | Overlapping & visual quality | Incision suturing/PKP |
| López-Ferrando & Medrano- Ruiloba41 (2016) | Eye rubbing | None | Late breaks (6%), ICRS migration (4%), & overlapping (2%) | No (100%) | NA | NR |
| Ibrahim et al.28 (2016) | KC | Vacuum loss | ICRS broke/inverted ICRS | No (100%) | NA | Moxifloxacin/prednisolone |
| Abdelmassih et al.32 (2017) | KC | None | Vascularization & corneal thinning | Yes (5,9%) | ICRS migration | Tobramycin/gatifloxacin |
| García de Oteyza et al.46 (2017) | KC | None | Whitish infiltrate, hypopyon, & CM | Yes (100%) | Staphylococcus aureus keratitis | Vancomycin, ceftazidime, moxifloxacin, tobramycin, dexamethasone, & loteprednol |
| Oatts et al.18 (2017) | Myopia | None | Epithelial defect, thinned cornea, & extrusion | Yes (100%) | FBS, photophobia, & VA | NR |
| Chan & Hersh19 (2017) | KC & PLE | NR | VA, diplopia, & halos | Yes (83,3%) | Low vision quality | Antibiotic and corticosteroid |
| Mounir et al.10 (2018) | KC | Vacuum loss, incomplete tunnel creation, ICRS migration, AC perforation, inverted ICRS, & broken ICRS | ICRS migration, extrusion, Incision opacification, steroid-induced glaucoma, infectious keratitis, crystalline sterile keratitis, & CM | Yes (0,8%) | ICRS migration, infectious keratitis, & perforation into the anterior chamber | Moxifloxacin/prednisolone |
| Elbaz et al.47 (2018) | KC | None | Spontaneous in situ breakage | Yes (100%) | Pain, redness, & FBS | Antibiotics & corticosteroid |
| Nguyen et al.29 (2019) | KC & PLE | NR | Microbial keratitis, photophobia, FBS, & VA | Yes (6%) | Refractive/topographic considerations | Gatifloxacin & vancomycin |
| Iqbal et al.51 (2019) | KC | NR | Migration (1,6%), extrusion (4,7%), & KC progression (6,4%) | Yes (6,3%) | ICRS migration & extrusion | Gatifloxacin/prednisolone |
| Tabatabaei et al.34 (2019) | PLE | NR | Keratitis | Yes (100%) | Keratitis | Cefazolin/amikacin/vancomycin |
Quality Assessment Tool for Case Series Studies
| Author (Year) | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 |
|---|
| Quantock et al.43 (1995) | Yes | Yes | No | No | Yes | No | No | No | No |
| Asbell et al.12 (1999) | Yes | Yes | No | No | Yes | No | No | No | No |
| Bourges et al.23 (2003) | Yes | Yes | No | No | Yes | No | No | No | No |
| Shehadeh-Masha'our et al.22 (2004) | Yes | Yes | NA | NA | Yes | No | No | NA | Yes |
| Güell et al.35 (2004) | Yes | No | No | Yes | Yes | No | Yes | Yes | Yes |
| Alió et al.48 (2004) | Yes | Yes | No | Yes | Yes | Yes | No | No | Yes |
| Hofling-Lima et al.24 (2004) | Yes | Yes | No | Yes | No | No | Yes | No | No |
| Kwitko & Severo50 (2004) | Yes | Yes | No | Yes | Yes | Yes | Yes | Yes | Yes |
| Kanellopoulos et al.20 (2006) | Yes | Yes | No | Yes | Yes | Yes | Yes | Yes | Yes |
| McAlister et al.36 (2006) | NA | CD | NA | NA | Yes | Yes | Yes | NA | NA |
| Galvis et al.37 (2007) | NA | CD | NA | NA | Yes | Yes | Yes | NA | NA |
| Carrasquillo et al.30 (2007) | Yes | Yes | NR | Yes | Yes | Yes | Yes | Yes | Yes |
| Zare et al.31 (2007) | Yes | Yes | NR | Yes | Yes | Yes | Yes | Yes | Yes |
| Cosar et al.11 (2009) | NA | CD | NA | NA | Yes | Yes | Yes | NA | NA |
| Ibáñez-Alperte et al.44 (2010) | Yes | Yes | NA | NA | No | No | NR | NA | No |
| Alió et al.13 (2010) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Ferrer et al.14 (2010) | Yes | No | No | NR | Yes | Yes | Yes | NA | Yes |
| Mulet et al.33 (2010) | Yes | Yes | No | NA | Yes | Yes | No | NA | Yes |
| Chalasani et al.45 (2010) | NA | CD | NA | NA | Yes | Yes | Yes | NA | NA |
| Kugler et al.40 (2011) | Yes | No | No | No | Yes | No | Yes | NA | Yes |
| Rayward et al.38 (2011) | NR | No | NA | NA | No | No | NR | NA | No |
| Coskunseven et al.8 (2011) | Yes | Yes | No | Yes | Yes | Yes | Yes | No | Yes |
| Shihadeh49 (2012) | Yes | Yes | NA | NA | No | No | Yes | NA | Yes |
| Bali et al.15 (2012) | Yes | Yes | No | No | Yes | Yes | Yes | No | Yes |
| Yeung et al.16 (2013) | Yes | Yes | No | No | Yes | Yes | Yes | NA | Yes |
| Jarade et al.42 (2013) | Yes | No | No | Yes | Yes | NR | CD | NA | NR |
| Neira et al.39 (2014) | NR | Yes | No | Yes | Yes | Yes | NR | NA | Yes |
| Chhadva et al.17 (2015) | Yes | Yes | No | Yes | Yes | Yes | Yes | NA | Yes |
| López-Ferrando & Medrano-Ruiloba41 (2016) | NR | No | No | No | Yes | Yes | Yes | NA | Yes |
| Ibrahim et al.28 (2016) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Abdelmassih et al.32 (2017) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| García de Oteyza et al.46 (2017) | NA | CD | NA | NA | Yes | NA | NA | NA | Yes |
| Oatts et al.18 (2017) | NA | CD | NA | NA | Yes | NA | NA | NA | Yes |
| Chan & Hersh19 (2017) | NA | CD | NA | NA | Yes | NA | NA | NA | Yes |
| Mounir et al.10 (2018) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Elbaz et al.47 (2018) | NA | CD | NA | NA | Yes | NA | NA | NA | Yes |
| Nguyen et al.29 (2019) | Yes | No | Yes | NA | Yes | No | NA | NA | Yes |
| Iqbal et al.51 (2019) | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Tabatabaei et al.34 (2019) | Yes | Yes | Yes | Yes | No | Yes | Yes | Yes | Yes |
Study Characteristics
| Author (Year) | Design | Conflict | Inclusion Criteria | Exclusion Criteria | Follow-up (wks) | Patients (% Male) | N (Eyes) | ICRS Type | ICRS Per Eye | Age (y) |
|---|
| Quantock et al.43 (1995) | CR | No | NA | NA | 32 | 1(100%) | 1 | Manual Keraring | 1 | 46 |
| Asbell et al.12 (1999) | CR | No | NA | NA | 40 | 1 (NR) | 1 | Manual Keraring | 2 | 28 |
| Bourges et al.23 (2003) | CR | No | NA | NA | 240 | 1 (0%) | 1 | Manual Intacs | 2 | 41 |
| Shehadeh-Masha'our et al.22 (2004) | CR | No | Ectasia | No complications | 12 | 1 (100%) | 1 | Manual Intacs | 2 | 53 |
| Güell et al.35 (2004) | CS | No | Myopia PL | NA | 12 to 40 | 8 (NR) | 13 | Manual Intacs | 2 | NR |
| Alió et al.48 (2004) | CA | No | ICRS explanted | NA | 48 | 4 (NR) | 5 | Manual Intacs | 1/2 | 32, 51 (50% NR) |
| Hofling-Lima et al.24 (2004) | CS | No | Keratitis | NA | 88 | 8 (37.5%) | 8 | Ferrara (87.5%), Intacs (12.5%) | NR | 32 |
| Kwitko & Severo50 (2004) | CS | No | KC | NA | 52 | 47 (NR) | 51 | Manual Ferrara | 2 | NR |
| Kanellopoulos et al.20 (2006) | CS | No | KC | NA | 48 | 15 (40%) | 20 | Manual Intacs | 2 | 30.2 |
| McAlister et al.36 (2006) | CR | No | NA | NA | 3 | 1 (100%) | 1 | Manual Ferrara | 2 | 34 |
| Galvis et al.37 (2007) | CR | No | NA | NA | 16 | 1 (0%) | 1 | Manual Ferrara | 2 | 42 |
| Carrasquillo et al.30 (2007) | CS | No | KC & PLE | Corneal scarring | 6 to 49 | 29 (55%) | 33 | 50% Manual; 50% FS Intacs | 1/2 | 39 |
| Zare et al31 (2007) | CS | No | KC & CLI | Leucoma | 24 | 22 (77%) | 30 | FS Intacs | 1/2 | 26 |
| Cosar et al.11 (2009) | CR | No | NA | NA | 144 | 1 (100%) | 1 | Manual Intacs | 2 | 33 |
| Ibáñez-Alperte et al.44 (2010) | CR | No | KC | NA | approx 7 | 1 (NR) | 1 | Manual Intacs | 2 | 36 |
| Alió et al.13 (2010) | CS | No | KC, ICRS explanted | NR | 24 | 21 (NR) | 21 | Manual / FS Intacs & Keraring | 1/2 | 36 |
| Ferrer et al.14 (2010) | CS | No | ICRS explanted | NR | 336 | 47 (51%) | 57 | Manual / FS Intacs & Keraring | 1/2 | 37 |
| Mulet et al.33 (2010) | CS | No | Keratitis | NR | 4 | 149 (59%) | 212 | Manual / FS Intacs & Keraring | 1/2 | 35 |
| Chalasani et al.45 (2010) | CR | No | NA | NA | 12 | 1 (0%) | 2 | Ferrara | 1 | 40 |
| Kugler et al.40 (2011) | CS | No | Ectasia | No complications | approx 28 | 279 (NR) | 279 | FS Intacs | 1/2 | 44.25 |
| Rayward et al.38 (2011) | CR | No | KC G II | NA | 2 | 1 (100%) | 1 | NR | 1 | 26 |
| Coskunseven et al.8 (2011) | CA | NR | KC G II to III, CT > 350 µm | Herpes or keratitis | NR | 531 (NR) | 850 | FS Keraring | NR | 28.32 |
| Shihadeh49 (2012) | CR | No | KC moderate myopia | NA | approx 20 | 1 (100%) | 2 | NR | 1 | 34 |
| Bali et al.15 (2012) | CS | No | KC (4), ectasia (6) | No Intacs surgeries | 48 | 9 (66.6%) | 10 | FS Intacs | 1/2 | 44.5 |
| Yeung et al.16 (2013) | CS | No | KC | NA | 12 | 3 (66.6%) | 6 | Intacs | 2 | 21.6 |
| Jarade et al.42 (2013) | CS | No | ICRS migration | No surgery complications | 24 | 2 (NR) | 2 | Intacs / Keraring | 1 | NR |
| Neira et al.39 (2014) | CS | NR | Atopic dermatitis AKC | No surgery complications | NR | 5 (40%) | 5 | Manual Intacs | 1/2 | 32.6 |
| Chhadva et al.17 (2015) | CS | Yes | KC | Manual implantation | 48.5 | 8 (50%) | 10 | FS INTACTS | 2 | 38 |
| López-Ferrando & Medrano-Ruiloba41 (2016) | CS | NR | KC | NA | 36 to 168 | 35 (NR) | 50 | Manual Ferrara | 1/2 | NR |
| Ibrahim et al.28 (2016) | CS | Yes | KC, CLI, CT > 450 µm | Haze, hydrops infection | 24 | 100 (43%) | 160 | FS Keraring | 1/2 | 21.77 |
| Abdelmassih et al.32 (2017) | CS | No | ICRS & CXL | Keratitis or IOL | 24 to 208 | 12 (83.35%) | 17 | FS Keraring & Intacs | 1/2 | 12.3 |
| García de Oteyza et al.46 (2017) | CR | No | NA | NA | NR | 1 (100%) | 1 | FS Ferrara | 2 | 13 |
| Oatts et al.18 (2017) | CR | No | NA | NA | 84 to 240 | 2 (50%) | 3 | Manual Intacs | 2 | 33 |
| Chan & Hersh19 (2017) | CR | No | NA | NA | 8 to 104 | 3 (33%) | 3 | FS Intacs | 1/2 | 49.67 |
| Mounir et al.10 (2018) | CS | No | KC G II to III, CT > 350 µm | PLE, hydrops, KC G IV | 52 | 417 (49.4%) | 623 | FS Keraring | 1/2 | 22.27 |
| Elbaz et al.47 (2018) | CR | No | NA | NA | 16 | 1 (100%) | 1 | Manual Ferrara | 2 | 37 |
| Nguyen et al.29 (2019) | CS | Yes | KC PLE | NA | NR | 31 (71.4%) | 35 | FS Intacs | 1/2 | 41 |
| Iqbal et al.51 (2019) | CS | No | KC G I, II, or III | NA | 72 | 37 (NR) | 63 | FS Keraring | 1/2 | 9 to 17 |
| Tabatabaei et al.34 (2019) | CR | NR | NA | NA | 26 | 11 (72,7%) | 11 | Keraring, Intacs, MyoRing, & AICI | NR | 29 |