arce pachymetry keratoconus - galilei

Financial Disclosure: Financial Disclosure: Carlos G. Carlos G. ArceArce MD:MD:

Territory Manager for Latin America, Vista Optics Limited, Territory Manager for Latin America, Vista Optics Limited, WidnesWidnes, UK, UKResearch & Development Consultant, Research & Development Consultant, ZiemerZiemer Group AG, Port, SwitzerlandGroup AG, Port, Switzerland

Speaker, Bausch & Lomb do Speaker, Bausch & Lomb do BrasilBrasilAuthor does not have financial interest in the commercializationAuthor does not have financial interest in the commercialization of equipments mentionedof equipments mentioned

CarlosCarlos G. G. Arce,Arce, MDMD

Tips on Galilei’s Optical PachymetryTips on Galilei’s Optical Pachymetry

Associate Researcher and Ophthalmologist Ocular Bioengineering & Refractive Surgery Sectors, Institute of Vision

Department of Ophthalmology, Paulista School of MedicineFederal University of São Paulo, Brazil

New Trends in Corneal TopographyNew Trends in Corneal Topography

Normal Values with GalileiNormal Values with Galilei


Traffic light color distribution gives a meaning to scales of curvature, pachymetry and

elevation maps

2nd yellow:2nd yellow:47 D in Curvature (1 D step)

500 500 μμmm in Thickness (15in Thickness (15--20 20 μμm step)m step)15 μm in Elevation (5 μm step)

2nd green:2nd green:44 D in Curvature

530 or 560 530 or 560 μμmm in Thickness in Thickness Zero μm in elevation

RED = STEEP, THIN or HIGH RED = STEEP, THIN or HIGH STOP!STOP!YELLOW = BORDER LINE YELLOW = BORDER LINE CAUTION!CAUTION!

GREEN = NORMAL GREEN = NORMAL GO AHEAD!GO AHEAD!BLUE = FLAT, THICK or DEEP BLUE = FLAT, THICK or DEEP BLUE = FLAT, THICK or DEEP WHY?WHY?WHY?

Corneal Pachymetry is not only one value Corneal Pachymetry is not only one value


Normal distribution pattern: • Central warmer zone with concentric rings• Normal difference between peripheral and central average seems to be 150-200 μm

Corneal Pachymetry is not only one value Corneal Pachymetry is not only one value


Galilei default distribution of colorsis better because have 6 instead of only 3 green steps for normal range


12

12

3

3

4

4

5

5

6

6

7

7

8

89

9

101112

Normal Slope

Steep Slope

Thickness Progression Profile Thickness Progression Profile

Number of steps using scales of 15 μm or 20 μm

• Simple and practical• No need of graphics or curves


High astigmatism with KPI = 0%Normal slope: <10 steps of 20 μm




Assymetric curvature with KPI = 14%Border line slope: 10 steps of 20 μm



Keratoconus with KPI = 76%Steep slope: 13 steps of 20 μm

ThicknessThickness progression may be assymetricprogression may be assymetric

TPI: TThickness PProgression IIndex derived from overall linear regression

y = Ax + B TP = (TPI) d + T0

TPI = TP – T0d


12 steps of 20 μm

A

B

Examples:TPIA = (647-501)/5.2 = 28.07 μm/mmTPIB = (690-501)/2.4 = 78.75 μm/mm

Future: Color maps made from TPI

Thinnest Point and Pupil Thinnest Point and Pupil CentroidCentroid

• Alzamora JB, Stillitano I, Maidana EJ, Arce CG, Schor P, Campos M, Chalita MR, Sartori M.Variação espacial da espessura da cónrea medida por paquimetria quantitativa de área.

In: Arce C, Francesconi M, Nose W Editors. Concenso Orbscan. Cultura Medica. RJ. In press

TN


Thinnest point thinner than 500 μm AND located beyond 1 mm from the pupil centroid is KCN until demonstrate against

PachymetryPachymetry MapMap


Clinic correlation with TopographyClinic correlation with Topography


ThinningThinning

HealingHealing

Deepness of opacitiesDeepness of opacities

Horizontal Slit

Vertical Slit


Deepness of corneal layersDeepness of corneal layers


Courtesy of Sonia Yoo, MD Courtesy of Sonia Yoo, MD ––Bascom Palmer Eye InstituteBascom Palmer Eye Institute

• Incongruency of anterior & posterior curvature

• Thick cornea with asymetric and uncommon pattern

≈ 590-610 μm

CCT 654 μm

≈ 691-714 μmInferiorEpithelium

Densitometry Max 31 %

KCN in Fuchs

with thick cornea

• KCN Report: KPI = 40.6 %

arce pachymetry keratoconus - galilei

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