Sections

Workup

Imaging Studies

Corneal topography

Corneal topography development provides surgeons with effortlessly understood color-coded maps of corneal curvature in addition to quantitative indexes of irregular astigmatism that correlate with potential visual acuity.

Modern instrumentation produces a videokeratograph, which generally is in the form of a color-coded contour map.

Different manufacturers use different methods (eg, Placido, 40 scanned slits, combination Placido and 40 scanned slits, phase modified laser holography, raster stereography).

The use of video keratography in the preoperative and postoperative evaluation of all patients undergoing refractive surgery is valuable.

Dual Scheimpflug analyzer

This is a high-precision optical system for corneal topography and 3-dimensional analysis of the anterior eye segment, based on a Revolving Dual Channel Scheimpflug Camera and a Placido Disk.

Placido imaging furnishes high accuracy curvature data.

Scheimpflug imaging is optimal for precise elevation data.

Pachymetry

The pachymeter (optical, ultrasonic) is used to measure corneal thickness.

Accurate determination of corneal thickness preoperatively allows the surgeon to set the depth of incision to two thirds of the measured result.

Orbscan II by Orbtek uses both 40 scanned slits and Placido methods to provide anterior and posterior corneal curvature in addition to data on corneal thickness.

Procedures

A manual corneal trephination set to create a corneal tunnel for intrastromal corneal ring segments has been available since the introduction of ICRS. Currently, most femtosecond laser units are able to create similar tunnels using a specific program. The femtosecond laser–created tunnels are more precise and result in less morbidity than the manual approach.

Treatment & Management

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Asbell PA, Ucakhan OO, Durrie DS, et al. Adjustability of refractive effect for corneal ring segments. J Refract Surg. 1999 Nov-Dec. 15(6):627-31. [Medline].
Colin J, Cochener B, Savary G, et al. Correcting keratoconus with intracorneal rings. J Cataract Refract Surg. 2000 Aug. 26(8):1117-22. [Medline].
Colin J, Cochener B, Savary G, et al. INTACS inserts for treating keratoconus: one-year results. Ophthalmology. 2001 Aug. 108(8):1409-14. [Medline].
Alio J, Salem T, Artola A, et al. Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis. J Cataract Refract Surg. 2002 Sep. 28(9):1568-74. [Medline].
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Fleming JF, Wan WL, Schanzlin DJ. The theory of corneal curvature change with the Intrastromal Corneal Ring. CLAO J. 1989 Apr-Jun. 15(2):146-50. [Medline].
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Ito M, Arai H, Fukumoto T, et al. INTACS before or after laser in situ keratomileusis: correction of thin corneas with moderately high myopia. J Refract Surg. 2004 Nov-Dec. 20(6):818-22. [Medline].
Linebarger EJ, Song D, Ruckhofer J, et al. Intacs: the intrastromal corneal ring. Int Ophthalmol Clin. 2000 Summer. 40(3):199-208. [Medline].
Rosen E, Kowalewski E. Instrument for initiating the corneal intrastromal channel for the insertion of Intacs. J Cataract Refract Surg. 2001 Sep. 27(9):1356-8. [Medline].
Ferrara Ring surgical kit. Ferrara Ring. Available at http://www.ferrararing.com.br/en/products. Accessed: 08/15/2013.
Holmes-Higgin DK, Baker PC, Burris TE, et al. Characterization of the aspheric corneal surface with intrastromal corneal ring segments. J Refract Surg. 1999 Sep-Oct. 15(5):520-8. [Medline].
Burris TE, Holmes-Higgin DK, Silvestrini TA, et al. Corneal asphericity in eye bank eyes implanted with the intrastromal corneal ring. J Refract Surg. 1997 Sep-Oct. 13(6):556-67. [Medline].
Colin J, Velou S. Implantation of Intacs and a refractive intraocular lens to correct keratoconus. J Cataract Refract Surg. 2003 Apr. 29(4):832-4. [Medline].
Hellstedt T, Makela J, Uusitalo R, et al. Treating keratoconus with intacs corneal ring segments. J Refract Surg. 2005 May-Jun. 21(3):236-46. [Medline].
Donnenfeld ED. Intacs vs LASIK for Low Myopia. AAO Refractive Surgery Subspecialty Day Manual. 2000.
Baikoff G, Maia N, Poulhalec D, et al. [Diurnal variations of refraction and keratometry after intracorneal rings]. J Fr Ophtalmol. 1999 Mar. 22(2):169-75. [Medline].
Barach D, Mortemousque B, Bertel F, et al. [Fluctuations in uncorrected visual acuity after refractive surgery using intra-stromal corneal rings]. J Fr Ophtalmol. 1999 Apr. 22(3):335-8. [Medline].
Nio YK, Jansonius NM, Wijdh RH, et al. Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus. J Cataract Refract Surg. 2003 Nov. 29(11):2082-95. [Medline].
Twa MD, Hurst TJ, Walker JG, et al. Diurnal stability of refraction after implantation with intracorneal ring segments. J Cataract Refract Surg. 2000 Apr. 26(4):516-23. [Medline].
Burris TE. Intrastromal corneal ring technology: results and indications. Curr Opin Ophthalmol. 1998 Aug. 9(4):9-14. [Medline].
Tran DB, Zadok D, Carpenter M, et al. Intraocular pressure measurement in patients with intrastromal corneal ring segments. J Refract Surg. 1999 Jul-Aug. 15(4):441-3. [Medline].
Grabner G, Ruckhofer J, Tratter C, et al. [The intrastromal corneal ring (KeraVision Ring, ICR, ICRS). A modern method for correcting minor myopia]. Wien Med Wochenschr. 1997. 147(12-13):309-21. [Medline].
Assil KK, Barrett AM, Fouraker BD, et al. One-year results of the intrastromal corneal ring in nonfunctional human eyes. Intrastromal Corneal Ring Study Group. Arch Ophthalmol. 1995 Feb. 113(2):159-67. [Medline].
Schanzlin DJ, Asbell PA, Burris TE, et al. The intrastromal corneal ring segments. Phase II results for the correction of myopia. Ophthalmology. 1997 Jul. 104(7):1067-78. [Medline].
Twa MD, Karpecki PM, King BJ, et al. One-year results from the phase III investigation of the KeraVision Intacs. J Am Optom Assoc. 1999 Aug. 70(8):515-24. [Medline].
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Alió JL, Artola A, Hassanein A, et al. One or 2 Intacs segments for the correction of keratoconus. J Cataract Refract Surg. 2005 May. 31(5):943-53. [Medline].
Kessler D, El-Shiaty AF, Wachler BS. Evaluation of tear film following Intacs for myopia. J Refract Surg. 2002 Mar-Apr. 18(2):127-9. [Medline].
Fleming JF, Lovisolo CF. Intrastromal corneal ring segments in a patient with previous laser in situ keratomileusis. J Refract Surg. 2000 May-Jun. 16(3):365-7. [Medline].
Edelhauser HF. The resiliency of the corneal endothelium to refractive and intraocular surgery. Cornea. 2000 May. 19(3):263-73. [Medline].
Holmes-Higgin DK, Burris TE, Lapidus JA, et al. Risk factors for self-reported visual symptoms with Intacs inserts for myopia. Ophthalmology. 2002 Jan. 109(1):46-56. [Medline].
Azar RG, Holdbrook MJ, Lemp M, et al. Two-year corneal endothelial cell assessment following INTACS implantation. J Refract Surg. 2001 Sep-Oct. 17(5):542-8. [Medline].
Clinch TE, Lemp MA, Foulks GN, et al. Removal of INTACS for myopia. Ophthalmology. 2002 Aug. 109(8):1441-6. [Medline].
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Bourcier T, Borderie V, Laroche L. Late bacterial keratitis after implantation of intrastromal corneal ring segments. J Cataract Refract Surg. 2003 Feb. 29(2):407-9. [Medline].
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Nose W, Neves RA, Burris TE, et al. Intrastromal corneal ring: 12-month sighted myopic eyes. J Refract Surg. 1996 Jan-Feb. 12(1):20-8. [Medline].
Nosé W, Neves RA, Schanzlin DJ, et al. Intrastromal corneal ring--one-year results of first implants in humans: a preliminary nonfunctional eye study. Refract Corneal Surg. 1993 Nov-Dec. 9(6):452-8. [Medline].
Kymionis GD, Siganos CS, Kounis G, et al. Management of post-LASIK corneal ectasia with Intacs inserts: one-year results. Arch Ophthalmol. 2003 Mar. 121(3):322-6. [Medline].
Barbara A, Shehadeh-Masha'our R, Zvi F, et al. Management of pellucid marginal degeneration with intracorneal ring segments. J Refract Surg. 2005 May-Jun. 21(3):296-8. [Medline].
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Media Gallery

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.

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Author

Manolette R Roque, MD, MBA, FPAO Department Chairman and Chief of Section on 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

Manolette R Roque, MD, MBA, FPAO is a member of the following medical societies: American Academy of Ophthalmology, American Uveitis Society, European Society of Cataract and Refractive Surgery, International Ocular Inflammation Society, Philippine Academy of Ophthalmology, Philippine College of Surgeons, Philippine Medical Association, Philippine Ocular Inflammation Society, Philippine Society of Cataract and Refractive Surgery, University of the Philippines Medical Alumni Society

Disclosure: Nothing to disclose.

Coauthor(s)

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, Philippine Academy of Ophthalmology, Philippine Society of Cataract and Refractive Surgery, Philippine Society of Pediatric Ophthalmology and Strabismus

Disclosure: Nothing to disclose.

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.

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

Michael Taravella, MD Director of Cornea and Refractive Surgery, Rocky Mountain Lions Eye Institute; Professor, Department of Ophthalmology, University of Colorado School of Medicine

Michael Taravella, MD is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, American Society of Cataract and Refractive Surgery, Contact Lens Association of Ophthalmologists, Eye Bank Association of America

Disclosure: Received income in an amount equal to or greater than $250 from: J&J Vision (Consultant)/Proctor<br/> for: Coronet Surgical (Consultant), no income received.

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.

Design	Technique
360° ICR	Radial incision
360° ICR	Circumferential incision
Gapped ICR	Radial incision
Intacs inserts	Radial incision

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

Intracorneal Ring Segments Workup

Imaging Studies

Corneal topography

Dual Scheimpflug analyzer

Other Tests

Pachymetry

Procedures

Intracorneal Ring Segments Workup

Imaging Studies

Corneal topography

Dual Scheimpflug analyzer

Other Tests

Pachymetry

Procedures

References

Tables

Contributor Information and Disclosures

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