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      Late extrusion of intrastromal corneal ring segments: A report of two cases

      case-report

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          Abstract

          Purpose

          To report two cases of patients with late extrusion following uneventful implantation of intrastromal corneal ring segments (ICRS) for myopia.

          Observations

          Two patients with previously implanted ICRS for low myopia presented with spontaneous onset of extrusion of their ICRS, one at 7 years post-operatively and the other at 17 and 20 years. Both cases underwent explantation and maintained excellent best-corrected visual acuity. These cases represent the longest reported intervals between implantation of the ICRS and subsequent extrusion.

          Conclusions and importance

          Late extrusion can occur many years following implantation of ICRS, even in eyes without pre-existing thinning or ectasia. The technique for explantation described herein can result in favorable clinical outcomes in such cases. These cases demonstrate the importance of long-term follow up of eyes that have undergone ICRS implantation.

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          Histopathological findings after intracorneal ring segment implantation in keratoconic human corneas.

          David Touboul, Joseph Colin, François Léger … (2007)
          To evaluate histopathological changes induced in keratoconic corneas after implantation of Intacs intracorneal ring segments (Addition Technology, Inc.). Departments of Ophthalmology and Pathology, Hospital Pellegrin, Bordeaux, France. This retrospective study included 8 keratoconic, contact-lens-intolerant eyes of 8 patients who had penetrating keratoplasty (PKP) after removal of Intacs inserts because of a poor refractive outcome or insert extrusion. Light microscopy was performed on all specimens after conventional staining. Immunohistochemistry was performed to identify cell types located next to the tunnel using AE1/AE3 cytokeratins, CD34, vimentin, collagen IV, and alpha-smooth muscle actin monoclonal antibodies. Conventional histology showed hypoplasia of the epithelium immediately surrounding the channel. There was no evidence of an inflammatory response or foreign-body granuloma. Keratocyte density was decreased above and below the tunnel, and collagen IV synthesis was seen in the scar area. All samples stained negatively with alpha-smooth muscle actin, indicating that myofibroblasts were not present. These changes were no longer visible when PKP was performed more than 6 months after Intacs explantation. Intacs induced keratocyte apoptosis, probably through a switch to a collagenous synthetic phenotype. Although histological changes seem to be entirely reversible after implant removal, longer follow-up is necessary to determine whether they accelerate corneal thinning and keratoconus progression via apoptosis and release of metalloprotease.
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            The intrastromal corneal ring segments. Phase II results for the correction of myopia.

            D Schanzlin, Silas Burris, D S Durrie … (1997)
            The purpose of the study was to evaluate the safety and efficacy of the intrastromal corneal ring segments (ICRS) for the correction of myopia. A 2-year phase II clinical trial of ICRS was initiated in May 1995. The investigational plan specifies that 150 patients with sighted eyes, requiring myopic corrections from -1.00 to -6.00 diopters (D), will each receive ICRS in 1 eye. The patient population will be divided into approximately five patients per ICRS thickness (0.25, 0.30, 0.35, 0.40, and 0.45 mm) per site. Six investigational sites are participating in the trial. Fifty-nine men and 43 women requiring myopic corrections were enrolled at four U.S. investigational sites. These 102 patients each received the ICRS product in 1 eye. Correction of myopia. Efficacy of ICRS was assessed with respect to the trial endpoints of predictability of refractive effect, uncorrected visual acuity (UCVA), stability of UCVA, maintenance of best spectacle-corrected visual acuity and stability of refractive effect. As shown by the available month-3 data (99 patients; all device thicknesses), 95 (96%) of 99 patients had a UCVA of 20/40 or better. Ninety-eight (99%) of 99 patients were within 2 lines of their preoperative best spectacle-corrected visual acuity. The average change (with standard error) in cycloplegic refraction (spherical equivalent) achieved by ICRS thickness was -1.27 +/- 0.09 D (0.25 mm), -2.13 +/- 0.16 D (0.30 mm), -2.56 +/- 0.15 D (0.35 mm), -3.77 +/- 0.37 D (0.40 mm) and -4.16 +/- 0.24 D (0.45 mm). Seventy-seven percent (76/99) of the patients were within +/-1.00 D of their intended correction. When the ICRS was removed in two cases, both patients returned to within 0.75 D of their preoperative manifest refraction. The ICRS appears to be a viable and effective alternative for the treatment of myopia. Additionally, as indicated by the explant data, the ICRS's refractive effect may be reversible upon removal of the device.
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              Two-year outcomes of intrastromal corneal ring segments for the correction of myopia.

              David Schanzlin, Richard L Abbott, Penny Asbell … (2001)
              To evaluate the safety and efficacy of Intrastromal Corneal Ring Segments (ICRS) for the correction of myopia. Nonrandomized, comparative trial. Patients enrolled in the United States Food and Drug Administration phase II and phase III clinical trials of the ICRS had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, myopia of -1.00 to -3.50 diopters (D), and a cylindrical correction of 1.00 D or less as measured by manifest refraction. Surgical correction of myopia with an ICRS. Efficacy was assessed by predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), stability of refractive effect, and postoperative uncorrected visual acuity. Safety was assessed by adverse events, maintenance or loss of preoperative BSCVA, and induced manifest refraction cylinder. Four hundred fifty-two patients were enrolled at 11 investigational sites in both studies. Of the 454 surgical attempts, 449 received an ICRS in one eye (0.25, 0.30, and 0.35 mm in 148, 151, and 150 eyes, respectively). First surgeries were attempted in 452 patients. An ICRS was successfully implanted in 447 initial eyes, and 5 surgeries were discontinued. Of the five discontinued surgeries, three patients subsequently exited from the study, and two patients went on to have the ICRS implanted in the second eye, bringing the total number of successful implants to 449 patient eyes. Month 24 postoperative follow-up was completed on 358 patients (80%). At month 24, 328 of 354 eyes (93%) were within +/-1.00 D of predicted refractive outcome. Refraction changed by 1 D or less in 97% of eyes (421/435) between 3 and 6 months after implantation and in 99% (343/348) between months 18 and 24. Before surgery, 87% of eyes (390/448) saw worse than 20/40 uncorrected; 24 months after surgery, 55% of eyes (196/358) saw 20/16 or better, 76% (271/358) saw 20/20 or better, and 97% (346/358) saw 20/40 or better. Although two eyes (2/358; 0.5%) lost two or more lines of BSCVA at 24 months; visual acuity in both was 20/20 or better. Intraoperative complications included anterior corneal surface perforation (three eyes) and anterior chamber perforations (two eyes, one during an attempted exchange procedure); all healed spontaneously without suturing and without loss of BSCVA. The ICRS was repositioned in five eyes to increase correction. Postoperative complications in one eye each were infectious keratitis, shallow segment placement, and loss of two lines of BSCVA at two or more consecutive examinations (subsequently regained). The ICRS safely, predictably, and effectively reduced or eliminated myopia of -1.00 to -3.50 D. The refractive effect was stable over time.
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                Author and article information

                Contributors
                David G. Hwang
                Journal
                Journal ID (nlm-ta): Am J Ophthalmol Case Rep
                Journal ID (iso-abbrev): Am J Ophthalmol Case Rep
                Title: American Journal of Ophthalmology Case Reports
                Publisher: Elsevier
                ISSN (Electronic): 2451-9936
                Publication date PMC-release: 06 October 2017
                Publication date Collection: December 2017
                Publication date (Electronic): 06 October 2017
                Volume: 8
                Pages: 67-70
                Affiliations
                [a ]Cornea Service, Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA
                [b ]Division of Ophthalmology, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
                Author notes
                [∗ ]Corresponding author. Department of Ophthalmology, University of California, San Francisco, 10 Koret Way, San Francisco 94143-0730, CA, USA.Department of OphthalmologyUniversity of California, San Francisco10 Koret WaySan FranciscoCA94143-0730USA david.hwang@ 123456ucsf.edu
                Article
                Publisher ID: S2451-9936(16)30294-8
                DOI: 10.1016/j.ajoc.2017.10.004
                PMC ID: 5731710
                SO-VID: b2269aa2-1a63-4589-98f6-b22371397d46
                Copyright © © 2017 The Authors
                License:

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                Date received : 1 December 2016
                Date revision received : 20 July 2017
                Date accepted : 2 October 2017
                Categories
                Subject: Case report

                Keywords: intrastromal corneal ring segments,intracorneal rings,extrusion,complications,refractive surgery,myopia
                Data availability:
                Keywords: intrastromal corneal ring segments, intracorneal rings, extrusion, complications, refractive surgery, myopia

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