INTACS SK nomogram

C OM P R E H E N S I V E N OM O G R AM

A N D P R E -‐ S U R G I C A L P L A N N I N G G U I D EUPDATED

February 1, 2011

A D D I T I O N T E C H N O L O G Y I N C .The Leader In Corneal Sc ience & Implant Technology

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AddiEon Technology in collaboraEon with highly experienced Intacs surgeons have analyzed thousands of cases over a mulE-‐year period to provide a “best pracEces” approach to pre-‐surgical planning.

The goal of Intacs is to restore functional vision by re-shaping the cornea from within the stromal layers thus changing the optical properties of the cornea. The following nomogram, pearls and pre-‐surgical plan-‐ning steps have been created to assist you with your ini-‐Eal cases. AddiEonal pearls and Eps are available via your on-‐line account at www.addiEontechnology.com. Contact your representaEve for further assistance with pre-‐surgical planning and case review.

Keratoconus Nomogram -‐ Intacs SKChoose symmetric or asymmetric segments using the following guidelines:

Use the symmetric chart when the cone on the posterior float is within the central 3-‐5 mm opEcal zone and the sphere power is greater than the cylinder power on the manifest re-‐fracEon notated in posiEve cylinder.

Use the asymmetric chart when the cone on the posterior float is located outside the 3 mm geometric center and the cylinder power is greater than the sphere power on the manifest refracEon notated in posiEve cylinder.

When the sphere power is equal to or similar to the cylinder power on the manifest refrac-‐Eon notated in posiEve cylinder, use the symmetric chart however, consider asymmetric chart when cone is de-‐centered or superior-‐nasal periphery shows considerable flaWening compared to inferior-‐temporal periphery. See Verifier 3.

SYMMETRICSYMMETRICSYMMETRICSphere Power Inferior Intacs SK Superior Intacs SK

-‐0.000 to -‐1.000 D 0.210 mm 0.210 mm-‐1.000 to -‐2.000 D 0.250 mm 0.250 mm-‐2.000 to -‐4.000 D 0.300 mm 0.300 mm-‐4.000 to -‐6.000 D 0.350 mm 0.350 mm-‐6.000 to -‐8.000 D 0.400 mm 0.400 mm

* -‐8.000 D to -‐10.00 D 0.450 mm 0.450 mm

* NOTE: In high Myopic cases over -‐10.00 Diopters in plus cylinder notaEon where peripheral pachymetry is over 500 microns, .500 micron Intacs SK can be used.

ASYMMETRICASYMMETRICASYMMETRICCylinder Power Inferior Intacs SK Superior Intacs SK3.00 to 5.00 .350mm .210mm 5.00 to 7.00 .400mm .210mm

7.00 and higher .450mm .210mm

Quick Summary:

Step 1: View corneal topogra-‐phy and manifest refracEon.

Step 2: Verify steep meridian for incision locaEon.

Step 3: Select Intacs segments using nomogram on this page.

Intacs® SK Pre-‐Surgical Planning Guide & Comprehensive Nomogram

AddiEon Technology, Inc. -‐ © 2011 AddiEon Technology, Inc. All Rights Reserved -‐ Intacs® -‐ Plus Cylinder NotaEon

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Intacs Pre-‐Surgical Planning Guide Step 1: Measurements & Materials

Ideal measurements and materials:

• Manifest refracEon• BCVA / UCVA• Corneal topography

• Axial • Posterior Float• Keratometric (Numeric Overlay)• Pachymetry (at least 4-‐6 locaEons)

• Min K & Max K values (on topography)

Other measurements to consider notaEng and topography views include:

• Incision locaEon and depth (measured and actual)• Contact lens tolerance• Contact lenses prescribed (pre & post operaEve) • Endothelial cell counts are not necessary but may be helpful• Numeric Overlay• RefracEve Power (Front)• Mean Power Keratometric

DefiniDons:

Steep Meridian: IdenEfied as the manifest refracEon axis in posiEve cylinder notaEon or the topographical Max K axis.

Flat Meridian: IdenEfied as the manifest refracEon axis in minus cylinder notaEon or the topographical Min K axis. Corneal Topography & Incision LocaEon

Step 2: Incision Placement & Cone LocaDon

Verify steep meridian for incision placement. The manifest refracEon axis notated in posiEve cylinder and the Max K axis on topography should match. If they vary by ± 15°, see Verifier 2 for more details. The “red” line in image below idenEfies the steep meridian.

Using a posterior view, idenEfy if the cone is centered or de-‐centered by using the 3 mm, 5 mm and 7 mm markings on topography. Draw a line across the cornea in the direcEon of cone displacement (blue line in image on len). In most cases, the incision is placed superior-‐temporal on the steep meridian. See Verifier 1 below for more details.

Step 3: Segment SelecDon -‐ See nomogram on page 1

The keratoconic cornea has unique biomechanical properEes and asymmetric irregulariEes whereby a number of measurements may require verificaHon prior to surgery. The supporEng pages outline key verifiers helpful in enhancing results.



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Verifiers For Pre-‐Surgical Planning The refracEve power of the cornea is based on the curvature and symmetry of the corneal sur-‐face. In keratoconus, the corneal surface is irregular resulEng in compound / irregular asEgma-‐Esm. Each keratoconus case is unique with various irregular properEes that can be evaluated using diagnosEc data that has been idenEfied:

• With the Manifest RefracEon• From the BCVA / UCVA findings• Across the anterior surface of the cornea (keratometric values)• Within the stromal layers (pachymetry values)• From the corneal back surface (posterior float)

Verifier 1: Posterior Float -‐ Centered or De-‐centered

Centered cones typically call for symmetric segments whereas de-‐centered cones call for asym-‐metric segments. Using the posterior view showing cone displacement helps with choosing symmetric or asymmetric segments. EvaluaEng cone locaEon and displacement also aids in verifying the proposed incision locaEon & Intacs placement.

To idenEfy the proposed incision locaEon, draw a “blue” line across the center of the posterior view in the direcEon the cone is displaced. Then, draw a “red” line perpendicular to the “blue” line making a plus sign or “X” over the posterior view (See Figure 1). The blue line represents the flat meridian (where the Intacs will be placed) and the red line represents the steep merid-‐ian (where the incision will be placed). NoEce the Max K axis and manifest refracEon axis in posiEve cylinder notaEon should match.

Match Mis-‐Match



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Verifier 2: Manifest RefracDon vs Steep K (Max K) Axis & BCVA

Compare the axis in the manifest refracEon notated in posiEve cyl-‐inder to the Max K axis on topography. Is the BCVA 20/50 or beWer? In an ideal case, the Max K axis and manifest refracEon axis in posi-‐Eve cylinder notaEon should match within 15ᴼ of each other and be located along the steep meridian idenEfied in Verifier 1.

Each case is unique. The BCVA provides us informaEon on how well the paEent sees with their current refracEon. When the BCVA is worse than 20/50, and/or the manifest refracEons axis in posiEve cylinder is ± 15° from the Max K axis, re-‐take the manifest refracEon and/or topography to confirm or conEnue to look at the verifiers in this guide.

Verifier 3: With-‐The-‐Rule AsDgmaDsm vs Against-‐The-‐Rule AsDgmaDsm & Corneal Imbalance

Color paWerns and K values on the keratometric view provide important informaEon for evaluat-‐ing corneal refracEve imbalance. First, idenEfy the steep and flat areas of the map by visual ob-‐servaEon of the map colors. Is there a clear dis-‐EncEon of blue (superiorly) and red (inferiorly)? Is the map mostly red? Does the overall paWern look like an hourglass? PMD (Crab claw)? Is the cone on the posterior view centered or de-‐centered?

Next, evaluate the K values on the keratometric view or use a numeric overlay view and evaluate K values across all areas of the map. If the map clearly shows a split of blue and red color in the 6 -‐ 7 mm diameter, idenEfy the steepest K values (circle them) and the flaWest K values (circle them). Then, idenEfy the K values that are most similar on opposite sides of each other (See fig-‐ure 2). In these cases, asymmetric segments are ideal unless the cone is centered on the posterior float (See figures 2 and 3).

If the map looks like a crab claw (PMD), noEce how the flaWest peripheral K readings are oppo-‐site the steepest peripheral K readings along the the flat meridian (See figure’s 2 & 3). In PMD to-‐pographical paWerns, the flaWest peripheral K reading is usually significantly less than the op-‐posing steep peripheral K reading (<41K). Also, noEce the two similar peripheral K readings op-‐posite each other located along the steep merid-‐ian circled in white in figure’s 2 & 3.

20/50Intacs® SK Pre-‐Surgical Planning Guide & Comprehensive Nomogram


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Figure 2

Figure 3

OpEcally, the asEgmaEsm in highly asym-‐metric PMD cases is typically against-‐the-‐rule and requires balancing inferior and su-‐perior to the steep meridian and can some-‐Emes be located along the oblique axis.

If the map looks like an incomplete crab claw (PMD-‐Like) or a highly irregular hour glass or snowman with a very small crooked head (see figure 4), noEce how the flaWest peripheral K readings are 90° away from the steep meridian. The asEgmaEsm in these cases is mostly oblique. Symmetric seg-‐ments are commonly recommended how-‐ever, asymmetric segments may be used depending on the posterior cone displace-‐ment, the amount of cylinder and how flat the superior side of the steep meridian shows.

If the map looks like an hourglass (see figure 5), noEce how the peripheral K readings are fairly similar and the two similar peripheral K readings opposite each other are located along the flat meridian. The asEgmaEsm in these cases is typically with-‐the-‐rule and requires balancing nasal and temporal to the steep meridian. The steep meridian axis may vary ± 15° and may someEmes be lo-‐cated along the oblique axis. Symmetric segments are commonly used.

Verifier 4: Pachymetry

IdenEfying the peripheral pachymetry can be an indicator for corneal health and can be a characterisEc in detecEng corneal ecta-‐sia 1. Thin peripheral readings can help verify cone displacement in some cases and can assist in verifying incision locaEon and placement.

1 R. Ambrósio Jr, Poster ASCRS 2006

Note: Determining segment selecHon is dependent upon the surgeons decision where to im-‐prove sphere and/or cylinder correcHon to best achieve a biomechanical and refracHve corneal balance.



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Figure 4

Figure 5

Corneal Topography Views & Various Cone Examples

-‐5.75 +3.75 x 123 -‐11.25 +3.50 x 47

-‐9.75 +2.25 x 56 -‐3.25 +5.75 x 162

-‐3.75 +5.50 x 30-‐8.75 +2.00 x 107

-‐5.25 +3.00 x 67 -‐4.50 +7.00 x 14



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Intacs Guidelines & Pearls

General Guidelines & Pearls

• Incision depth should be a minimum of 70%.• Snug incision closure with 10.0 nylon suture. Maintain for up to 2 months.• Keep cornea hydrated during surgery.• PaEents with pupils greater than 7 mm may be predisposed to low light sensiEvity such

as glare and halos and should be appropriately advised.• Single segments are not recommended.• It may take 3 – 6 months for visual acuity to stabilize. • When creaEng a channel where the cornea is thinnest, slowly advance the dissector

threading into stroma. If any resistance or wave-‐like appearance is seen with corneal Essue, slow or stop dissecEon/ inserEon unEl Essue adjusts.

• UElizing a disposable contact lens to manage spherical correcEon during the first 1 -‐ 6 months may aid in final contact lens success. Advise paEent of visual limitaEons due to no cylindrical correcEon with disposables.

• Contact lens fiyng can start as early as 6 weeks with the understanding that vision may fluctuate for up to 3 – 6 months before stabilizing.

• In high Myopic cases with spherical power over -‐10.00 Diopters in plus cylinder notaEon, where peripheral pachymetry is over 500 microns, .500 micron Intacs SK is available.

• Vision conEnues to improve over Eme. 3,4

PaDent Acceptance Criteria

• PKP a consideraEon• Diagnosis indicates ectaEc condiEon• Contact lens intolerant (Clear central cornea)• Pachymetry at least 450μ at incision locaEon

Femtosecond Guidelines

• Inner diameter seyng: 6.0 / Outer diameter seyng: 7.0• If channels too Eght, increase outer diameter seyng by 0.1 mm unEl desired width is

achieved.

Your AddiEon Technology representaEve is a valuable resource for updates, addiEonal pracEce informaEon, training and guidance. More informaEon can also be found by joining the ATI Phy-‐sician Network at www.AddiEonTechnology.com/eye.

3 Long-‐term Follow-‐up of Intacs in Keratoconus, George D. Kymionis, MD, PHD, et al, Am J Ophthalmol. 2007 Feb;143(2):236-‐244. Epub 2006 Nov 30.4 My First Intacs Case – 10 Year Stability, Prof. Joseph Colin, Presented at the American Academy of Ophthalmology, 2007.

Cover image courtesy of Oscar Pineros, M.D.



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The Worldwide Leader In Corneal Science & Implant Technology

950 Lee Street, Suite 210Des Plaines, IL 60016Phone: (847) 297-‐8419Fax: (847) 297-‐8678

intacs@Addi\onTechnology.com

AddiEon Technology would like to thank all the Intacs surgeons worldwide for their conEnued contribuEons to the Intacs technology and nomogram. The Intacs Nomogram is based on Intacs technology -‐ the

only ICRS in the world having undergone clinical trials. ReproducEon of the nomogram for use with any other technology is prohibited.Intacs® and Intacs® SK are registered trademarks of AddiEon Technology Inc.

© 2011 AddiEon Technology, Inc. All Rights Reserved.

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INTACS SK nomogram

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