Intracorneal Ring Segments Workup: Imaging Studies, Other Tests, Procedures

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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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].
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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.

of 8

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

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

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.

Intracorneal Ring Segments Workup

Imaging Studies

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