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Intracorneal Ring Segments Treatment & Management

  • Author: Manolette R Roque, MD, MBA, FPAO; Chief Editor: Hampton Roy, Sr, MD  more...
 
Updated: Mar 15, 2016
 

Medical Therapy

Medical therapy is limited to broad-spectrum topical antibiotics and corticosteroids for uncomplicated cases.

See Postoperative details and/or articles on ocular pharmacology for more information.

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Surgical Therapy

See Intraoperative details for the surgical procedure.

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Preoperative Details

The procedure for placement of the intrastromal ring and ring segments is similar, and both can be performed with topical anesthesia. The operative field is prepared, and the patient is prepared and draped in the usual sterile fashion for ophthalmic surgery. A lid speculum is used for globe exposure.

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Intraoperative Details

Manual intrastromal corneal pocket creation

The corneal center is identified and marked with a Sinskey hook.

A 2-mm long epithelial impression is created at the 12-o'clock position, where the ring segments are to be placed at an 8-mm diameter optical zone.

A diamond blade, set at 65% of the peripheral corneal depth, is used to perform a radial incision along this mark. See the image below.

The 1.2-mm radial incision is made with a diamond The 1.2-mm radial incision is made with a diamond knife at the edge of a 7-mm optical zone. The diamond knife is set for approximately two thirds of corneal depth. Reprinted with permission of Addition Technology Inc.

A vacuum-centering guide is positioned relative to the central corneal indentation.

The vacuum is increased, and the guide is circumferentially adhered onto the perilimbal conjunctiva, stabilizing the globe. This device provides a guide for the dissector. The dissector is inserted into the radial incision, and blunt dissection of the cornea at two-thirds depth is performed in the clockwise and counterclockwise directions to create 2 stromal channels. See the image below.

Rotation of the dissector creates the tunnel in th Rotation of the dissector creates the tunnel in the peripheral cornea into which an Intacs insert will be placed. Reprinted with permission of Addition Technology Inc.

The vacuum is released, and the vacuum-centering guide is removed.

Ring segments are inserted through the radial incisions using special forceps and are positioned using a Sinskey hook nasally and temporally, such that the superior ends are approximately 3 mm apart. See the images below.

The first Intacs insert is placed in the tunnel. R The first Intacs insert is placed in the tunnel. Reprinted with permission of Addition Technology Inc.

The incision is closed with 1 or 2 interrupted 11-0 nylon sutures.

An Intacs insert in place at approximately two thi An Intacs insert in place at approximately two thirds of corneal depth. Reprinted with permission of Addition Technology Inc.
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Postoperative Details

Postoperatively, antibiotic-corticosteroid combination drops and/or ointment are used, and the speculum is removed. The eye may be covered overnight with a shield. Antibiotic-corticosteroid combination drops are used 4 times daily for 1 week. The sutures are removed 2 weeks postoperatively or longer if the incision is not healed adequately.

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Follow-up

Patients are seen postoperatively on day 1, week 1, and months 1, 3, 6, and 12. The surgeon should watch for postoperative complications. An observations timeline has been outlined for potential complications. See Complications.

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Complications

Complications include localized incision-related epithelial defects, epithelial plug formation, wound dehiscence, superficial neovascularization, surgically induced astigmatism, infiltrates in the channel, transient decreased corneal sensation, and delayed infectious keratitis.[49, 50] Other observations included haze and deposits around the intrastromal channel.

Observations timeline consists of the following:

  • Immediate (1-7 d)
  • Early (1-4 wk)
  • Intermediate (after 4 wk)
  • Immediate postoperative observations may include epithelial defects, lamellar channel haze, undercorrection and overcorrection, and incision-healing responses.
  • Early postoperative observations may include sterile infiltrates, epithelial cysts or plugs, and infectious keratitis.
  • Late postoperative observations may include positioning hole deposits, lamellar channel deposits, and infectious keratitis. [51, 52]

Exchange or explantation

In selected patients with undercorrection or overcorrection, an exchange procedure can be done. In selected patients who are dissatisfied, an explantation procedure can be done. The procedures can be done with the patient using only topical anesthesia. The surgical steps are listed below:

  • Early in the postoperative period, a Sinskey hook can be used to reopen the original incision, or, if the original incision is healed, a radial incision is made at the original site at the same depth as the original incision.
  • Fibrous tissue is gently loosened with blunt dissection.
  • A Suarez spreader is used to dissect the channel opening.
  • A Sinskey hook is then used to engage the positioning hole and to rotate the segment out of its channel.
  • In cases of exchange, a new ICR segment can then be placed into the previously made channel.
  • The incision is closed with a suture.
  • The same postoperative procedure is followed as with the original insertion.
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Outcome and Prognosis

A summary of the safety and efficacy variables at 12 months after surgery is as follows:

  • Uncorrected visual activity (UCVA) 20/20 or better (74%); UCVA 20/40 or better (97%)
  • Mean refractive spherical equivalent (MRSE) ± 0.50 D (69%); MRSE ± 1.00 D (92%)
  • Greater than or equal to 2 lines loss best spectacle corrected visual acuity (0%); increased cylinder greater than or equal to 2.00 D (0%)
  • Corneal topography demonstrated that, while general flattening of the central cornea occurs, the normal positive asphericity of the cornea is maintained after placement of the ring and ring segments. [53]
  • Transient dry eye may follow the placement of Intacs inserts, but the tear film quality returns within 1 week after surgery. [54, 13, 55, 56, 57]
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Future and Controversies

Applications of intrastromal ring segments include the following:

  • Myopia with astigmatism - Going beyond the range that has been approved by the FDA; currently, the upper limit is at -3.00 D spherical equivalent at the spectacle plane.
  • Astigmatism - Applications in patients with pure astigmatism; currently, the upper limit is at +1.00 D of astigmatism.
  • Presbyopia - In presbyopes and patients previously treated with LASIK or PRK
  • Therapeutic indications - The use of Intacs in patients with mild corneal ectasia not deemed to be candidates for LASIK or PRK [14, 58]
  • Therapeutic indications - By flattening the central corneal protrusion, intracorneal ring implantation is a promising new therapy for patients with early-to-moderate pellucid marginal degeneration (PMD) and who are intolerant of contact lenses. [59, 60, 61, 62]
  • Therapeutic indications - Intracorneal ring segments are now used in the management of ectatic corneal diseases. [63]
  • Combination refractive procedures – Both the LASIK-Intacs method and the Intacs-LASIK method resulted in significant improvement in visual acuity and refraction based on limited experience. LASIK followed by Intacs may be the preferred procedure for reasons of safety, convenience, and lower induced cylinder.
  • Enhancement - The correction of residual myopia following maximum corneal sculpting with LASIK or PRK (posterior stromal bed too thin for further ablation); improving the conditions of patients with decreased nighttime visual function (including halos, induced myopia, and decreased contrast sensitivity) following LASIK and PRK, associated with constricted optical zones. [64]
  • Enhancement - Implantation of Intacs in eyes with myopic regression after LASIK and PRK resulted in a good refractive outcome and an improvement in uncorrected visual acuity. [65]
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Contributor Information and Disclosures
Author

Manolette R Roque, MD, MBA, FPAO Section Chief, Ocular Immunology and Uveitis, Department of Ophthalmology, Asian Hospital and Medical Center; Section Chief, Ocular Immunology and Uveitis, International Eye Institute, St Luke's Medical Center Global City; Senior Eye Surgeon, The LASIK Surgery Clinic; Director, AMC Eye Center, Alabang Medical Center

Manolette R Roque, MD, MBA, FPAO is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Philippine Medical Association, American Uveitis Society, International Ocular Inflammation Society, Philippine Ocular Inflammation Society, American Society of Ophthalmic Administrators, American Academy of Ophthalmic Executives, Philippine Society of Cataract and Refractive Surgery

Disclosure: Nothing to disclose.

Coauthor(s)

Ruben Limbonsiong, MD 

Ruben Limbonsiong, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery

Disclosure: Nothing to disclose.

Roberto Pineda, II, MD Director, Refractive Surgery Service, Massachusetts Eye and Ear Infirmary; Associate Professor of Ophthalmology, Harvard Medical School

Roberto Pineda, II, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery

Disclosure: Received consulting fee from Amgen for review panel membership; Received consulting fee from Genzyme?Sanofi for review panel membership; Received consulting fee from Novartis for consulting; Received consulting fee from Beaver-Visitec for consulting.

Barbara L Roque, MD, DPBO, FPAO Senior Partner, Roque Eye Clinic; Chief of Service, Pediatric Ophthalmology and Strabismus Section, Department of Ophthalmology, Asian Hospital and Medical Center; Active Consultant Staff, International Eye Institute, St Luke's Medical Center Global City

Barbara L Roque, MD, DPBO, FPAO is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American Society of Cataract and Refractive Surgery, Philippine Society of Cataract and Refractive Surgery, Philippine Academy of Ophthalmology, Philippine Society of Pediatric Ophthalmolo

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Louis E Probst, MD, MD Medical Director, TLC Laser Eye Centers

Louis E Probst, MD, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, International Society of Refractive Surgery

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy, Sr, MD Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy, Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Additional Contributors

Daniel S Durrie, MD Director, Department of Ophthalmology, Division of Refractive Surgery, University of Kansas Medical Center

Daniel S Durrie, MD is a member of the following medical societies: American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology

Disclosure: Received grant/research funds from Alcon Labs for independent contractor; Received grant/research funds from Abbott Medical Optics for independent contractor; Received ownership interest from Acufocus for consulting; Received ownership interest from WaveTec for consulting; Received grant/research funds from Topcon for independent contractor; Received grant/research funds from Avedro for independent contractor; Received grant/research funds from ReVitalVision for independent contractor.

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KeraVision Intacs microthin prescription inserts. Reprinted with permission of Addition Technology Inc.
KeraVision Intacs microthin prescription inserts. Intracorneal ring segments. Reprinted with permission of Addition Technology Inc.
The 1.2-mm radial incision is made with a diamond knife at the edge of a 7-mm optical zone. The diamond knife is set for approximately two thirds of corneal depth. Reprinted with permission of Addition Technology Inc.
Rotation of the dissector creates the tunnel in the peripheral cornea into which an Intacs insert will be placed. Reprinted with permission of Addition Technology Inc.
The first Intacs insert is placed in the tunnel. Reprinted with permission of Addition Technology Inc.
An Intacs insert in place at approximately two thirds of corneal depth. Reprinted with permission of Addition Technology Inc.
Graphic representation of the intracorneal ring segments in place. Reprinted with permission of Addition Technology Inc.
Intacs microthin prescription inserts treat mild myopia. Reprinted with permission of Addition Technology Inc.
Table 1. Evolution of Intacs Inserts
Design Technique
360° ICR Radial incision
360° ICR Circumferential incision
Gapped ICR Radial incision
Intacs inserts Radial incision
Table 2. Predicted Nominal Correction and Recommended Prescribing Range
Intacs thickness (mm) Predicted nominal correction (D) Recommended prescribing range (D)
0.25 -1.30 -1.00 to -1.625
0.30 -2.00 -1.75 to -2.25
0.35 -2.70 -2.375 to -3.00
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