Topo and Imaging - coavision.org

1

University Hospitals Eye Institute 1Please no cameras or recorders during the class presentation. You will be asked to leave the room if request is not followed.

201Corneal Imaging in the Modern

Optometric PracticeLoretta Szczotka-Flynn, OD, PhD

Room: Crystal C

#OptoWest

University Hospitals Eye Institute 2

#OptoWest

Make sure to check in and out for each course – you must do this even if you are staying in the same room for multiple courses.

Hand in your course ticket as you leave the class in order to receive credit. The ticket is the ONLY way to receive credit for this course.

If you must leave the class for any amount of time keep in mind if you are out of the room for more than 10 minutes, you will not receive any CE credit.

There will be a “coffee break” in the exhibit hall, sponsored by VSP Global, Friday and Saturday from 10:30am to 11:30am.


Please remember to complete the evaluation forms on the back of your course tickets.

A special thank you goes to our industry sponsors: Vision West, VSP Global, Vision West, VSP Global, AllerganAllergan, , CooperVisionCooperVision, Alcon, Practice Management, , Alcon, Practice Management, EssilorEssilor and and GenzymeGenzyme for their support of this conference.

If you have a cell phone or pager, please turn it off. If you must take a call, do so outside the room.

#OptoWest


201 – Corneal Imaging in the Modern Optometric PracticeLoretta Szczotka-Flynn, OD, PhD

This course material and information was developed independently of any assistance.

I have the following financial relationships to disclose:• Alcon: Honorarium/Writing & Speaking• Bausch & Lomb: Honorarium & Travel/Speaking• Vistakon: Research Grant/Research

University Hospitals Eye Institute 5Please no cameras or recorders during the class presentation. You will be asked to leave the room if request is not followed.

201Corneal Imaging in the Modern

Optometric PracticeLoretta Szczotka-Flynn, OD, PhD

Room: Crystal C

#OptoWest

LORETTA SZCZOTKA-FLYNN OD, PhD

CORNEAL IMAGING IN THE MODERN OPTOMETRIC PRACTICE

2

University Hospitals Eye Institute

LORETTA SZCZOTKA-FLYNN O.D.,Ph.D.,F.A.A.O.(Dipl)

Professor

Dept. of Ophthalmology

Case Western

Reserve University

Director: Contact Lens Service

UH Eye Institute


TOPICS FOR TODAY

• Corneal Topography

• Anterior Segment OCT

• Confocal Microscopy


Corneal Topography:

• Is the gold standard in contact lens practices• Acceptance credited to:

– lowered prices

– smaller instruments

– portable instruments

– software enhancements


Contact Lens Applications

• Standard map displays – Select qualitative designs

• spherical, toric, aspheric• appraisal of corneal apex; bifocals

– Select quantitative parameters• BC, PC, OAD, OZ

• Contact lens software modules• Other software modules

– KC detection, shape indices, irregularity

• Monitor CL induced change • Pachymetry• Wavefront analysis•


LIMITATIONS OF THE KERATOMETER

• Power and curvature at visual axis only• Qualitative assessment of regularity

– No interpretation or quantitative data

• Measures 4 points 3.6mm apart– 5% of the corneal surface (depends on K’s)– Lacks central & peripheral data

• Assumes sphero-cylindrical surface• Assumes orthogonal symmetry


Subjective Keratometry Errors

3


Mapping the Cornea

• Placido Disc Topography

• Rasterstereography– Par Vision Systems; elevation; based on stereo-photography

• Interferometry– Euclid System; Elevation topography

• Scanning Slit Topography– Orbscan II (includes placido)

• Scheimpflug– Pentacam


Reflective and Slit-scan Technologies

• One image, one surface.• Angle-dependent specular

reflection.• Measures slope (as a

function of distance).

• Multiple images, multiple surfaces.

• Omni-directional diffuse backscatter.

• Triangulates elevation.

Two prevailing technologies have been used for corneal topography. Both have advantages and disadvantages. The overwhelming advantage of slit-scan systems is that they measure multiple ocular surfaces.

Placido reflective systems can only measure the anterior tear film. ORBSCAN measures the anterior cornea, posterior cornea, and the anterior lens and iris.


What are the choices?Placido Disc Systems

• Optikon/Eyequip– Keratron; Scout

• Humphrey Instr.– Atlas

• Medmont– Medmont E300

• Technomed Tech– Technomed, colored rings

• Tomey Tech.– TMS-1, 2, 3

• Topcon– Infrared Placido unit

• Nidek– combo Placido, spatial refractometer

• Orbscan II

• Others

* discontinued* discontinued


Placido curvature may be ambiguous.d

ista

nt p

atte

rnd

ista

nt p

atte

rn

convex surface

concave surface

R > 0

image is smalland erect

image is smalland inverted

R < 0

Placido images

To see why, compare convex and concave test surfaces. The only difference is the direction (erect or inverted) of the specular image.Curvature ambiguity arises precisely because erect and inverted Placido images look identical.

Reflective devices can suffer other ambiguities.

Because of its inherent symmetry, Placido reflective corneal topography can NOT disambiguate a central hill from a central depression.

Both appear as a local increase in curvature, that is, as “central islands”.


Avoiding Artifacts and Misinterpretation

• 1) Eyelid position

• 2)Ring digitization errors

• 3) Color scales

• 4) Corneal apex alignment

• 5) Selecting the correct map


1) Eyelid Position

• Keratron only– eyelash breaks ring pattern

– acquires image when not in focus

4


2) Ring Digitization

• Long vs Short Working Distance Systems

Long Working Distance SystemsLong Working Distance Systems


• Short Working Distance System


View the placido image


3) Decoding Color Scales

• Absolute Scale– Standard

• Normalized Scale– Color Map

– Autosize

• Adjustable Scale– Customized


Absolute Scale

• Fixed Color Coded Scheme– Always assigns same color to a given dioptric interval

– Forces data to fit within a predetermined range


Saturated scales

• Can saturate extreme ends of scales• Tomey 9-100 D

• Keratron 9-101.5 D

• EyeSys/Premier 35-52 D

• Humphrey 39-50 D

5


Absolute Scale

• Advantages– Visually compare eyes or occasions

– Quickly visualize significant corneal changes

– Quick insight for best CL fitting approach

• Disadvantages– Large dioptric range

– Large intervals• Local irregularities may be masked

– Less detail if scale saturates


Normalized Scale

• Automatic subdivision of each cornea into equal, adjusted, dioptric intervals – Set number of colors to fill dioptric range

– Color intervals vary between eyes/occasions

– Usually smaller intervals than axial maps• Min 0.40 D steps Tomey

• Min 0.50 D steps EyeSys/Premier

• Min 0.25D steps Humphrey

University Hospitals Eye Institute 27 University Hospitals Eye Institute

Normalized Scale

• Advantages– Significantly more detail

– Highlights local irregularities

• Disadvantages– Can be misleading

– Cannot visually compare maps without referring to associated color scales

University Hospitals Eye Institute 29 University Hospitals Eye Institute 30

6


Scale selection in Contact Lens Fitting

• Absolute Scale– Quickly determine fitting approach based on

• Corneal Astigmatism

• Average corneal curvature

• Normalized – May sway the fitting approach if scale not referred to


Lower left:Spherical RGP orSoft toric

Lower right:Bitoric RGP withmachinable polymer

Upper left:Bitoric/LidAttachment

Upper right:Bitoric/InterpalpebralUniversity

Host


Relatively normal surfaces can appear complex due to minor variations.


Here are two anterior elevation maps from normal corneas that could be confusing to read. The color changes are presented using a standard scale in 5 micron steps. The problem with large step sizes is that it tends to mask large changes by lumping them into a limited number of color steps categories. Also by changing step sizes and scaling for different cases, one can easily get confused and under or over diagnose pathology.

Anterior Elevation Maps:Standard Color Scale


Nor

mal B

and

Nor

mal B

and

Scale

Scale

Stan

dard

Color

St

anda

rd C

olor

Sc

ale

Scale

A different approach is to set up a “normal band” or series of uniform color steps within which changes would not be considered pathological. In this way scale changes within a certain physiological range would all be represented by a single color and changes outside of the

range would show up as different colors.

The step size of the scale is user selected as is the center point and width of the normal band. For anterior and posterior corneal elevation maps I have chosen a step size of 5 microns. The center point of the normal band is zero deviation from the best fit sphere, and the width of the normal band is 50 microns, or 25 microns more elevated and 25 microns more depressed than the best fit sphere.

Elevation Color Scales

Everything in the normal band will be shown as green.

7


Normal Band Scale

On the left the standard scale for the normal anterior corneal surface is used and on the right the normal band scale is used showing an all green normal surface.

Standard Color Scale

Anterior Elevation


The normal band scale is a screening tool for gross pathology. Using the standard scale, the with-the-rule astigmatic pattern in this patient is obvious but is eliminated by use of the normal band scale.

Normal Band Scale

Standard Color Scale

Anterior Elevation


The normal band scale can also be used with 3-D Orbscan maps. The image on the lower right is the normal band representation of the cornea on the left.

Anterior Corneal Elevation


Here, the normal band scale on the lower right clearly demonstrates a posterior cone centrally in the 3-D posterior corneal surface elevation map.

Posterior Corneal Elevation


For keratometric curvature maps we’ve chosen a normal band of from 40 to 48 keratometric diopters. Within this range all values will appear as green on the Normal Band scale.

Keratometric Curvature Color Scales

Nor

mal B

and

Nor

mal B

and

Scale

Scale

Stan

dard

Color

St

anda

rd C

olor

Sc

ale

Scale

Editor Note: A keratometric curvature is any anterior surface curvature expressed in keratometric diopters [K]. Because of its dioptric evaluation, it has often been referred to as a power, although it is really a scaled surface curvature. That is, it is a geometric property, not an optical University Hospitals Eye Institute 42

Normal Band ScaleStandard Color Scale

It should be emphasized that this scale could be changed for individual needs and as shown here some rather significant changes can be masked so its usefulness with such a wide scale is for screening.

Tangential Curvature [K]

8


For corneal thickness we are using a normal band from 500 to 600 microns. Obviously this scale should be changed for post-Lasik or PRK eyes.

Corneal Thickness Color Scales

Nor

mal B

and

Nor

mal B

and

Scale

Scale

Stan

dard

Color

St

anda

rd C

olor

Sc

ale

Scale


Normal Band Scale

Corneal Thickness Map

Standard Scale

For corneal thickness we are using a normal band from 500 to 600microns. Obviously this scale should be changed for post-Lasik or PRK eyes.


Standard Scale Quad Map

This is a quad map of an untreated eye where the anterior corneal elevation map is shown on the upper left quadrant, the posterior corneal elevation map is on the upper right quadrant, corneal power map is on the lower left quadrant and corneal thickness map is on the lower right quadrant. Determining normal from abnormal features is certainly not obvious.


Posterior Keratoconus:Normal Band Scale

Here is the same eye using the normal band scale. The anterior elevation map on the upper left is now all green indicating a normal pattern. The corneal power map in the lower

left quadrant is virtually all yellow centrally indicating corneal powers between 40-48D.

The first appearance of abnormality is on the posterior corneal elevation map on the upper right where an area of central elevation is present with 2 areas of peripheral depression. On the corneal thickness map on the lower right a central area of corneal thinning below 500 microns is seen. The most likely diagnosis is a posterior cone with mild central corneal thinning.


The other eye of this patient underwent Lasik and here is that quad map using the standard scale.

Posterior Keratoconus:Standard Color Scale


4) Corneal Apex Position

• Classification of Normal Corneal Topography ; Bogan et al; Arch Ophthal 1990

• 399 normal corneas; Axial Maps• 22.6% round• 20.8% oval• 17.5% symmetric bow tie• 32.1 % asymmetric bow tie• 7.1% irregular

9


Primary GazePrimary Gaze UpgazeUpgaze


5) Selecting the Correct Display

• Placido Image

• Eye Image Overlay

• Axial

• Tangential

• Elevation

• Refractive

• Distortion/Irregularity

• Difference

• Serial Images

• Isometric

• Keratometric

• Meridional

• Numeric


Eye Image Overlay


Understanding the Maps

• Curvature Maps– Axial

• Sagittal

• Color

• Default

– Tangential• Instantaneous

• Local

• True

• Refractive Maps• Snell’s Law

• Power

• Elevation Maps• Height

• 3-D


Axial “radius of curvature”

• Distance along the normal from the corneal surface to the optic axis

• A reference distance, not a true curvature

• Most recognizable display

• Running avg/excludes extreme values

• Spherically biased

• Used in keratometry


Axial Curvature Map

Axial Curvature ( a.k.a. Color, Power, or Sagittal Map) displays a kind of radially-averaged curvature.This eye has with-the-rule astigmatism. The steep meridian is aligned with the red-shifted bow-tie.Axial curvature is measured exclusively in meridional planes (radial directions).The bow-tie is actually an axial artifact generated by the central intersection of the meridional planes.

Axial Curvature

10


Tangential radius of curvature

• Based on std. mathematical formula for local radius at a point along a curve

• Includes extreme curvature values

• Proportional to local curvature

• Derivative of axial data

• Axis independent

• More detail



Tangential maps for CL fittingTangential maps for CL fitting

• More accurate corneal shape– Correlated to slit lamp observations– RGP fluorescein patterns– Optical zone selection

• More detail– Detect irregular astigmatism– CL induced warpage– Monitor disease progression


Clinical Appearance of KC


Axial maps for CL fittingAxial maps for CL fitting

• Larger, diffuse patterns

• Less noise, but less detail

• Global representation of shape– More appropriate for spherical RGP curve selection

• Normals

• KC

• Post-Surgical/Oblate shapes


Axial maps in keratoconus

• Not sensitive enough for localized curvature changes off VK axis; which effects:

– Apex curvature and position• How does this effect RGP fitting?

– KC detection

– KC progression

11


Tangential maps in keratoconus

• POSSIBLE APPLICATIONS:– KC Progression

– Early KC detection (for PRK screening)

– KC Subset classification based on cone shape, size, and position

– KC Statistical Indices

– Contact Lens Fitting??



Elevation MapsElevation Maps

• Depict relative height differences from a reference sphere

• Reds: higher than reference sphere

• Blues: lower than reference sphere


high

sea-level

low

color contour map

terrain profile

Elevation, whether of the earth or the cornea, is measured relative to some reference surface. The terrestrial reference surface is the “mean sea level”.

Relative Elevation


With-the-Rule Astigmatism MapsAxial CurvatureElevation (sphere)

Elevation and axial curvature maps look different, almost reversed.On the axial map, the steep axis follows the sharpest curvature (red line segments) and aligns to the red-shifted bow-tie.On the relative elevation map, the steep axis dips below the reference surface and runs from “sea” to “sea”.

12


Topographical Elevation is Relative

5.6 mi 5.6 miles

12,000 miles

On a local scale these features are significant


Local clinical features (microns high) are a thousand times smaller than the cornea (millimeters in radius).This disparity in scale makes it IMPOSSIBLE to simultaneously map both the global curvature and clinically significant local elevation features of the cornea.To see clinically relevant features, corneal global curvature must first be removed. This is done by measuring elevation relative to some close-fitting reference surface, a process that inevitably introduces distortion.

Removing Global Curvature


Elevation Topology: Central Hill

The normal cornea is prolate, meaning that meridional curvature decreases from center to periphery.Prolateness of the normal cornea causes it to rise centrally above the reference sphere. The result is a central hill.

Sharp center

Flat periphery

Immediately surrounding the central hill is an annular seawhere the cornea dips below the reference surface.In the far periphery, the prolate cornea again rises above the reference surface, producing peripheral highlands.


Spherical reference surface

Elevation Distortion

Post Lasik profile

As an example of distortion, consider the corneal surface following myopic lasik correction. It is centrally flattened bythe surgery.To see surface features, elevation must be measured with respect to some reference surface.This relative elevation peak is NOT the highest point on the cornea.This apparent central "concavity" does NOT exist.

Relative elevation profile


Elevation (sphere) Elevation (sphere)

These are pre-op (left) and post-op (right) elevation maps of a myopic with-the-rule astigmatic eye corrected with LASIK.The post-operative central “sea” is not a concavity but a central flattening.The ring of relatively highest terrain is not absolutely higher (more anterior) than the “sea” bottom near the map center.


Close-Fitting Reference Surfaces

Topographic maps of terrestrial landscapes are displayed in the form of constant-elevation contours, measured from the “mean sea-level” of the earth.Corneal topography differs from terrestrial topography in that the reference surface is not some fixed “mean sea-level”, but is movable.

For the cornea, a reference surface (typically, a sphere) is constructed by fitting the reference surface as close as possible to the data surface.A best-fit minimizes the square difference (always a positive number) between the two surfaces, but only within a specified region known as the fit-zone.

Fit-zoneReference surface (sphere)

Data surface(cornea)

13


Elevation (sphere)10 mm fit-zone

Elevation (sphere)5 mm fit-zone

These elevation maps are the same exam of a normal eye having with-the-rule astigmatism. They differ only by the size of the fit-zone used to construct the reference sphere.Both maps contain exactly the same information. They look different, because altering the fit-zone changes the size and alignment of the reference sphere.

7.16 mm radius 6.88 mm radius University Hospitals Eye Institute 74

Default settings:• shape = sphere

Elevation Relativity

Changing the shape, size, or alignment of the reference surface changes the relative elevation, just like changing the mean sea level would change the heights of mountains.

The default reference surface is the best-fit sphere. Other reference surface shapes are used for special applications.The sphere is especially useful, because it is only reference surface with no unique symmetry axis (i.e., every diameter is a symmetry axis).

Two parameters define the best-fit sphere. Radius specifies size. Center location specifies alignment.The default sphere alignment is floating, which means its center location is unconstrained. Other alignments may force the reference sphere to lie on the map axis.

• alignment = floating


Float Center (C) Pin (P)same data surface

unconstrainedsphere center

constrainedsphere center

vie

w

a

xis

vie

w a

xis

vie

w

a

xis

Floating alignment imposes no additional constraints on the reference sphere. The sphere moves and changes size until it best-fits the data surface within the specified fit-zone.

Axial alignment imposes the center (C) constraint. The reference sphere center is forced onto the view axis, although it may move up or down the axis.

Pinned alignment imposes the pin (P) constraint, which forces the reference sphere surface to intersect the data surface on the view axis. The sphere center may be off axis.

“Apex” alignment imposes both center and pin (C+P)constraints. The sphere center lies is on the view axis, and the sphere surface intersects the data surface on the view axis.

Reference Sphere Alignments


Normal Eye: 4 Alignments

T NN T

Axial (C)Float ( )

Pin (P) Apex (C+P)

This is a normal eye with some with-the-rule astigmatism. The four elevation maps differ only by reference sphere alignment. The fit-zone is the largest 10 mm zone.Floating alignment (no constraints) reveals the natural symmetry of the eye. The reference sphere is slightly nasal and superior. This alignment displaces the central hill (arrow) inferiorly and temporally.

Applying the pin constraint raises the reference sphere. The sphere center still floats superior nasally, and the central hill (arrow) remains displaced inferior temporally.

Axial alignment centers the reference sphere, which artificially centers the central hill (arrow). Apex alignment centers and raises the reference sphere, which centers and lowers the central hill (arrow).

Elevation (sphere)


Artificial Alignment MapsElevation (sphere)Floating alignment

Elevation (sphere)Axial (C) alignment

This is a post-op exam of an originally myopic eye corrected with Lasik. The two elevation maps differ only by the alignment of the reference sphere.Floating alignment (left) shows the ablation (yellow circle) to be slightly offset in the pupil centroid (white dot) direction.Axial alignment (right), which forces the reference sphere center onto the map axis, moves the apparent ablation pattern 0.3 mm towards the map axis.Neither map is wrong, but floating alignment (no center constraint) allows the reference sphere to follow the natural symmetry of the surface.Neither map depression tracks the actual ablation edge, but only the smoothly varying corneal contour as seen from the reference sphere.


Elevation MapsElevation Maps

• Colors identical to curvature displays, but represent height only

• Steep(red) curvature does not always mean high!• Flat (blue) curvature does not always mean low!

14


Elevation maps for RGP fittingElevation maps for RGP fitting

• Most useful for RGP fluorescein patterns (vs. curvature maps):

– Reds: ALWAYS displace FL

– Blues: ALWAYS pool FL



Irregularity/Distortion MapsIrregularity/Distortion Maps

• Describes the visual limitations of the ocular surface– Humphrey Irregularity Map

• Local elevation differences between the actual corneal surface and the best fit regular toric surface

– EyeSys Holladay Display/Distortion Map



Difference Maps

Specialized software for Keratoconus Detection

15


Keratoconus Detection Software

Yaron Rabinowitz MD

Normals KC

Central 44.2+-1.6 49.9+-4.8

I-S Value 0.12+-0.57 3.7+-3.81

R vs L 0.42+-0.25 3.66+-3.25


Videokeratography PatternsVideokeratography Patterns

• Round

• Oval

• Superior Steep (SS)

• Inferior Steep (IS)

• Irregular

• Symmetric Bowtie (SB)

• SB/SRAX

• Asymmetric Bowtie AB/IS

• Asymmetric Bowtie AS/SS

• AB/SRAX


Videokeratographic Indices to Aid in Screening for KC

• Rabinowitz, Y. 1995– Central K > 47.20 D

– I-S Value >1.40 D

– SRAX >21 degrees

– Specificity=98%


KISA% indexRabinowitz Y, Rasheed K. JCRS 1999

• KISA%= K x I-S x AST x SRAX x 100300

– Clinically detectable KC • KISA%>100

– KC suspect• KISA% 60-100

– Advanced KC• KISA%>5000


MethodsMethods

• Quantitative Descriptors:– SRI; Surface Regularity Index

– SAI; Surface Assymetry Index

– SimK

– Central K

– I-S value

– C-P value

16


Defining Controls: Orbscan II

• In non-diseased eyes, the average amount of maximum posterior elevation using OrbscanII default settings compared to the best fit sphere is about 21-28 μm– Rao 2002

– Wei 2006

– Lim 2007

– Sonmez 2007



• One study of 140 normal eyes documented the maximum posterior elevation was never greater than 46 μm– Wei 2006

• Another study of 50 normal eyes the posterior elevation was never greater than 40 μm– Rao 2002



• Kollbaum (2006) delineated normals from clinically apparent KC– Posterior elevation was found to be the best performing single Orbscan

II index to detect KC• When highest elevation on the posterior surface was greater than 50 μm above the best-fit sphere.

– Sensitivity 0.93, Specificity 0.99, Accuracy 0.96.

Posterior Elevation on Orbscan II >50 microns indicative of Keratoconus


kjkjkjkjkjkjkjkjkjkjkjkj

lklklklklklklklklklklklklklklllklklklklklklklklkl

Figure 3


Defining Controls: Pentacam

• Posterior elevation ranges from -6 µm to + 18 µm in normals

• 15.5-32 μm of elevation on the posterior corneal surface can delineate forme frusteKC from normals

– de Su, Loiacono C, Richiardi L, et al Ophthalmology 2008 – Mihaltz K, Kovacs I, et al Cornea 2009 August 29.

• Feng et al recently published international values of corneal elevation in normals– Upper limits of normal for collective international data were 7.5 μm

and 13.5 μm at the posterior apex and posterior thinnest point, respectively.

17


Figure 1 Orbscan posterior elevation of same patient in Figure 2


Figure 2 Pentacamposterior elevation of same patient in Figure 1


Scheimpflug Cut-points

• Pentacam– Mean posterior elevation greater than 29-32 μm (in the central 5

mm cornea) is predictive

• Galilei Scheimpflug-based analyzer – Elevation in the central 7 mm zone > 50.5 μm was predictive

Posterior Elevation >30 microns on Pentacamsuggests keratoconus

Anterior Segment OCT

Slides courtesy of Mark Harrod

UH Eye Institute Ophthalmic Photographer


AS-OCT: What is it?

• An OCT with a lens adaptation

• Shows cross-sectional view of anatomy.– Cornea

– Angle

– Iris

– Lens

– Pachymetry

– Topography

• More detail than AS ultrasound


AS-OCT: What is it?

• SD-OCT– Scan speeds: up to 26,000 a-scan/sec

– Axial resolution of 5 microns

– Scan depth of 2 mm• Optovue RTVue with Cornea Adapter Module

• Heidelberg Spectralis with Anterior Segment Module

• Bioptgen Envisu

• TD-OCT– Scan speeds of 2000 a-scan/sec

– Axial resolution of 18 microns

– Scan depth up to 6 mm• Zeiss Visante Omni

18


AS-OCT: What is it?

• Comparison of TD-OCT vs SD-OCT

Figure from: Moyer S Cohen K. Anterior Segment OCT: A Comparison of Time Domain and Spectrial Domain Technologies J Ophthalmic Photography Summer 2009; Vol 31:90


AS OCT: What Are We Looking At?

• Corneal Thickness– Normal



• Corneal Thickness– Edema



• Corneal Thickness– Edema



• Corneal Thickness– LASIK Flap

Image Source: Optovue.



• Corneal Thickness– Keratoconus: Mild

19



• Corneal Thickness– Keratoconus: Moderate



• Corneal Thickness– Keratoconus: Severe



• Corneal Thickness– Keratoconus: Severe



• Corneal Pathology– DESEK




• Corneal Pathology– Abrasion



• Cornea Pathology– S/P PK

20



• Scleral Contact Lens Fitting




21





• Lens and Capsule– Normal




• Lens and Capsule– Captured IOL

22



• Iris Scans– Iris Cyst



• Iris Scans– Iris cyst



• Iris Scans– Iris Mass



• Iris Scans– Open Angle



• Iris Scans– Narrow Angle



• Iris Scans– Closed Angle

23



• Iris Scans– Closed Angle



• Iris Scans– Shunt


Confocal MicroscopyWhat Can it Show Me?


Confocal Microscopy: What is It?


Confocal Microscopy: What is It?

• Light Microscopy– Nidek CS4

• SLO– Heidelbeg HRT with Rostock Camera Module


Confocal Microscopy: What Are We Looking At?

• Normal– Z-Scan Showing Reflectance Peaks, Pachymetry

24



• Normal

Endothelium Posterior Stroma Anterior Stroma

Nerve Plexus Basal Epithelium Epithelium


Corneal Endothelial Image Analysis Parameters

• Cell density (cells/mm2)

• Cell area (µm2)

• Coefficient of variation – polymorphism or variation in cell

size

• % Hexagonal cells– pleomorphism or variation in cell

shape

Variable frame analysis

Corners Method/Morphometric Analysis


Analytic methods: A Fixed-frame analysis. B Variable-frame analysis. C Corners analysis. D Center analysis. E Center-Flex analysis. F Automated University Hospitals Eye Institute 142


• Normal • Low Cell Density



• Airbag Injury



• Airbag Injury

25



• Fuchs’ Dystrophy



• Epithelial Staining



• Acanthameoba Keratitis



• Acanthameoba Keratitis



• Fungal Keratitis



• Fusarium Keratitis

26


Confocal Images of Corneal Superficial EpitheliumPeriod 1 Day 1 Period 2 Day 35

10011024 L •photophobia •corneal thickness increase > 45m•corneal staining •Headache


Confocal of Corneal Basal Epithelial CellsPeriod 1 Day 1 Period 2 Day 35



Confocal of Cornea Mid-Stromal KeratocytesPeriod 1 Day 1 Period 2 Day 35


Stromal Reflectivity


The screen shots of Navis software


Lower reflective stroma

27


higher reflective stroma



PHMB solution user grade 2.5 stain

OD

OS


PHMB User NO STAIN


PHMB User: Grade 3 Stain

OD Baseline no stain

OD 5 month 3+ stain

Immune cells

28


100 microns


Resources:•Huang D, Duker J, Fujimoto J, Lumbroso B, Schuman J, Weinreb R eds, 2010: Imaging the Eye from Front to Back with RTVue Fourier-Domain Optical Coherence Tomography: Thorofare, NJ: Slack•Mastropasqua L, Nubile M, 2002: Confocal Microscopy of the Cornea: Thorofare, NJ: Slack•Holz FG, Schmitz-Valkenberg S, Spaide RF, Bird AC eds, 2007: Atlas of Autofluorescence Imaging: Heidelberg: Springer•Schmitz-Valkenberg S, Holz FG, Bird AC Spaide RF. Fundus Autofluorescence Imaging Review and Perspectives. Retina 2008; 28:385-409•Holtz FG, Dithmar S. 2008: Fluorescence Angiography in Ophthalmology: Heidelberg: Springer•Barry C, Morris P. eds, Journal of Ophthalmic Photography: Autofluoescence Supplement 2007; 29•Barry C, Morris P. eds, Journal of Ophthalmic Photography: SD OCT Supplement 2009; 31


Thank You.

Topo and Imaging - coavision.org

Documents

Transcript of Topo and Imaging - coavision.org