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Dimitrios G. Kyroudis Medical Director PIRAEUS LASER EYE CENTRE
Dimitrios G. Kyroudis
Medical Director
PIRAEUS LASER EYE CENTRE
Alcon WaveLight® Oculyzer II Diagnostic Device
PENTACAM(Oculus)
Rotating Scheimpflug camera
3-D modeling and analysis
of the anterior segment
Anterior corneal surface (ACS) elevation data
Posterior corneal surface (PCS) elevation data
Corneal pachymetry
Anterior chamber depth (ACD)
Lens thickness
AC IOL positioning data
Pupillometry
Opacities densitometry
Corneal Wavefront Zernicke & Fourier Analyses
Holladay report and Holladay EKR Detail Report
Belin /Ambrosio Enhanced Ectasia Display
The Scheimpflug principle
Preparation of data acquisition(Alignment focusing and identification
of the corneal apex as the reference point and the centre of the rotational scanning)
PENTACAM rotating Scheimpflug camera
data acquisition
Scheimpflug image(sagittal plane)
Calculated 3-D model
PENTACAM 4 MAPS REFRACTIVE
PENTACAM data acquisition specifications
ModelPENTACAM,
Oculyzer
PENTACAM
HR
Number of Scheimpflug images 50 100
Data points per surface 25000 138000
Points per scan (max) 500 1380
Distance between points on a single scan ≈20µm ≈ 7µm
Maximum distance between 2 adjacent
scans≈160µm ≈320µm
Acquisition time 2sec
Intacs for keratoconus
Flap visualisation and measurement of Residual Bed Thickness
Posterior capsule opacification
Cataract
Keratoconus
Basic curve necessity
Elevation data
Reference shape
(Best fit sphere)
Best fit sphere calculation
Fit zone
Best fit sphere
Cornea
What constitutes
normal or abnormal elevation?
9mm 10mm
11mm 12mm
Normal values are set for a specific fit zone
Elevation values for 8mm fit
Belin-Ambrosio
N=100
Anterior Apex
(μm)
Anterior
Thinnest (μm)
Posterior Apex
(μm)
Posterior
Thinnest (μm)
Average (±SD) 1.62±1.32 1.65±2.02 0.81±2.99 3.58±4.70
Range -5 to 4 -5 to 6 -6 to 6 -6 to 18
2SD/3SD 4.26/5.58 5.69/7.71 6.79/9.78 12.98/17.68
5% of the
population
(suspicious)
>4μm >6μm >7μm >13 μm
0.5% of the
population
(abnormal)
>6 μm >8 μm >10 μm >18 μm
TOPOGRAPHIC CRITERIA(Pentacam)
Anterior elevation >12-15μm Posterior elevation >20μm
(In astigmatic corneas the toric fit is assessed)Bow-tie assymetry >1,5DPosterior curvature >7DPentacam keratoconus screening & indicesKeratometric power deviation >1,8DPachymetry <500μm
…THEN PRK
The standard indices
The Belin Ambrosio Display (BAD II)
The Holladay Report
The standard indices
The Belin Ambrosio Display (BAD)
The standard BFS averages
all points of the surface
The enhanced BFS excludes
4mm around the thinnest point
thus making more prominent
the abnormal elevation
The Belin Ambrosio Display (BAD)
Enhanced BFS
The Belin Ambrosio Display (BAD)
The Belin Ambrosio Display (BAD II)
98% sensitivity detecting keratoconus
Not validated for corneas susceptible for keratectasia
(forme fruste, subclinical keratoconus)
8mm data can miss PMD changes
Does not pronounce cones
hidden in astigmatic surfaces
The Holladay Report
Tangential Curvature Map
Relative Pachymetry Map
Toric Ellipsoid Fit
The Holladay Report
Tangential nipple >48D
Posterior elevation on Toric Ellipsoid Fit >15μm
Relative Pachymetry >3.0%
The Holladay Report
Better for detecting cones on astigmatic corneas
Not validated
ΤΨΗΛΗΟΠΙΘΙΑ
ΚΑΜΠΛΤΛΟΣΗΣΑ
ΤΨΗΛΗΟΠΙΘΙΑ ΑΝΤΨΩΗ
ΚΡΟΣΑΦΙΚΑ
ΤΨΗΛΗΟΠΙΘΙΑ
ΑΝΤΨΩΗ
ΤΨΗΛΟΑΣΙΓΜΑΣΙΜΟ
ΤΨΗΛΗΠΡΟΘΙΑ & ΟΠΙΘΙΑ
ΑΝΤΨΩΗ(TORIC FIT)
ΑΤΜΜΕΣΡΙΑΚΛΕΨΤΔΡΑ
ΑΤΜΜΕΣΡΙΑΚΛΕΨΤΔΡΑ &
ΤΨΗΛΗ ΟΠΙΘΙΑΑΝΤΨΩΗ
ΤΨΗΛΟ ΑΣΙΓΜΑΣΙΜΟ
(WTR)
ΤΨΗΛΟΑΣΙΓΜΑΣΙΜΟ
(ATR)
Anterior cone
(borderline)
Holladay report
-ve
BAD II
Anterior
+ve
Form fruste
Keratoconus
OD
Holladay report
+ve
BAD II
-ve
Form fruste
Keratoconus
OS
Holladay report
-ve
BAD II
borderline
Suspicious
(asymmetry)
Holladay report
+ve
BAD II
+ve
Suspicious
Holladay report
-ve
BAD II
borderline
KK1
Holladay report
+ve
BAD II
+ve
