Corneal Tomography in Clinical Practice (Pentacam System): Basics and Clinical Interpretation Mazen M Sinjab
INDEX
Page numbers followed by f refer to figure and t refer to table.
A
Aberration 117f
analysis of 131
coma-like 120
compensation, internal 120
constant 122
fourth order 129
higher order 56, 107, 108, 118, 122, 124f, 125f, 129, 223
lower-order 91, 123
measurement of 118
residual higher-order 137
third order 129
types of 118
wavefront 117, 119
with age, changes of 120
Zernike description of 122, 123t
Aberrometers 118
ingoing
feedback 118
reflective 118
outgoing reflective 118
Aberrometry 223
in cataract surgery 223
wavefront 102
Achromatic axis 3
Alio-Shabayek
classification 178t
modification 177
Amsler-Krumeich
classification 177, 177t
grading system 177
standards 178t
Angulated patterns 46
Anisometropia 101, 102f
Arcuate incision 224f
Asphericity
patterns of 83
posterior surface 120
Astigmatic aberration 129
Astigmatic cornea, normal high 210f
Astigmatic disparity, probabilities of 110t
Astigmatic dissociation 108, 146
etiology 108
types of 109
Astigmatic keratotomy 149, 225
Astigmatic lower-order aberration 130f
Astigmatism 33, 91
against-the-rule 45, 45f, 52, 92
axis of 13
bioblique 226
classifications of 91
clinical manifest 108
compound 91
etiology of irregular 93
evaluation of irregular 100
mixed 92
irregular 93, 94f
posterior surface 149
secondary 131, 135f
simple 91
tomographic 108, 110113
topographic 110
unusual manifest 100
Asymmetric bowtie
inferior steep 46f
superior steep 46f
Asymmetric patterns 45
B
Belin ABCD keratoconus staging 161, 178, 179t, 184
Belin Ambrósio display 161, 168, 191, 194f, 197f, 199
map 193
Belin/Ambrosio ectasia display 60, 61f65f
Belin/Ambrosio enhanced ectasia 60, 60f
applications of 66
Bell pattern 68f
Bent frown incision 224f
Best fit ellipsoid 56, 57f
Best fit sphere 53, 57f, 82
Best fit toric ellipsoid 56, 57f
Butterfly 48f
C
Camera, bad exposure to 23, 152
Cataract 109
incision
location of 224
shape of 224
size of 224
type of 224
surgery 41, 149
Central flat island 96f
Central steep island 96f
Chamber angle, anterior 35
Chamber depth
anterior 35
range, anterior 13
Chamber volume, anterior 35
Circular pattern 67f
Clown face 49f
Color map appearance 13
Color scale 17
types of 17
Coma 129, 133f
aberration, comet from 134f
Cone 10
Contact lens 23, 143
soft 100f, 143, 144f
Conventional camera, imaging in 11f
Cornea 40, 50f, 214
abnormal 167t, 176
apparently normal 176
back, posterior surface 34
Fourier analysis of normal 140f
front, anterior surface 33
Guttata and Fuchs’ dystrophy 225
hyperprolate 84
infracentral 226
normal 86f, 176, 180f
high-astigmatic 211
low astigmatic 212, 213f
thin 169f
oblate 84, 85
optical center of 209
peripheral 220
prolate 84
shape of 131
thickness spatial profile 183
unclassified abnormal 176
volume 35
with abnormal elevation maps 64f
with high potential 167, 176
with normal elevation maps 63f
with suspicious posterior elevation map 65f
Corneal aberration 120
compensation 120
Corneal aberrometry in cataract surgery 223
Corneal and pupillary level 119
Corneal apex 6
Corneal asphericity 6, 82, 83f
affects 83
in emmetropia 83
in hypermetropia 84
in myopia 84
on curvature maps 84
on elevation maps 84
on refraction, effect of 83
on vision, effect of 83
Corneal astigmatism 52, 52f, 58f, 91, 105, 137
orientation of 45f
regular 52f
source of 6
Corneal asymmetry 85, 87f
horizontal 86f
on curvature maps 86
on elevation maps 86
Corneal changes with age 120
Corneal coma 137
Corneal cross-linking 181
Corneal curvature 152
map, patterns of 43
patterns of 43
Corneal dimensions 4
Corneal dioptric power 137
calculating objective 103
objective 103
Corneal disease 99
ectatic 87f
Corneal epithelium 6
on corneal shape, effect of 6f
Corneal flattening, postoperative 226
Corneal geometry 4, 8
measuring 8
of right eye 4f
Corneal graft 149, 203
after removal 98f
before suture removal 97f
Corneal induced irregular astigmatism 94
Corneal irregular astigmatism, nonectatic 94
Corneal irregularities 96t
reduces 6f
Corneal landmarks 34, 34f
Corneal maps and profiles 31
Corneal opacities 23, 149
Corneal optics and geometry 3
Corneal parameters 33, 34f
consists of 33
Corneal pathologies 149
Corneal periphery 22f, 194
Corneal power 6
maps 36
measurements of 38, 38t
measurement, factors affecting 36
Corneal refraction, understanding 89
Corneal refractive
power map, total 41
power, total 108
principle, total 42f
Corneal scar 69f73f, 224
peripheral 99f
Corneal shape 5, 82
left eye 5f
oblate 37f
Corneal sphere 137
Corneal steepening
incision-related 226f
postoperative 226
wound-related 226
Corneal surface
anterior 6, 36, 120, 182
posterior 4f, 34, 36
Corneal surgeries 149
previous 149
Corneal thickness 5, 152, 168, 183
central 183, 184
map 25f, 67, 162, 209
limitations 69
overlay for 30f
patterns 67
principle 67
profiles 67, 163, 183
spatial profile 67, 73, 74f
patterns 73
principle 73
thinnest 183, 214
Corneal tomography 102, 118, 165, 223
role of 223
Corneal topography 102
Corneal topometry 82
anterior 192, 193f, 195, 196f, 199f
Corneal toricity 82
on curvature maps 82
on elevation maps 82
Corneal trauma 98
Corneal warpage 143
Corneal wavefront 119
aberrations 118
Fourier analysis of 137, 138f
Corneal zones 5
Corrected distance visual acuity 101, 111, 170, 178, 225
Crab claw 48f
Crystalline lens 94
changes with age 120
Curvature
based devices (topographers) 8
based topography, limitations of 10
color scales for 20f
minimum radius of 179
posterior radius of 179, 184
radius of 5, 13
Curvature map 59, 59f
anterior 194, 196
sagittal 21f, 38, 44f
tangential 39
changes in 145
overlay 20
sagittal and tangential 47
Cycloplegic refraction 107
D
Decentered ablated zone 95f
Decentration 137
Defocus 128f
and pupil size 129f
Dioptric power, spherocylindric 103
Discrete pattern 202f
Droplet pattern 69, 69f
Dry eye 223
caused by 100f
Duochrome test 113
E
Ectasia 66, 167, 194f, 195
established 167
progressive posterior 184
Ectatic corneal disease 61, 83, 86f, 98, 103, 143, 165, 167, 167t, 177, 181, 182t, 191, 223
curvature asymmetry in 86f
grading systems of 177
per se 167
Ectatic corneal irregular astigmatism 94
Efficient optical zone 193f
Elevation maps 51, 59, 59f, 61f, 212
anterior 192, 194, 196, 198f
changes in 145
color
display in 55f
scale of 51f
irregular patterns on 58f
overlay 23
principle of 51, 51f
Elevation-based devices (tomographers) 10
Ellipse
blue 54f
red 54f
Emmetropic eyes 119
Enantiomorphism 153, 154f, 155f
in anterior elevation maps 156f
in curvature maps 156f
in posterior elevation maps 157f
in thickness maps 157f
Endothelium 13
Entities misdiagnosed ectasia 191
Epithelial basement membrane dystrophy 223
Examiner's error misalignment 144
Excess tears 152f
Eye
for capture, preparing 23
normal 61
superior view of right 3f
wavefront aberrations 118
F
Flat slope 73, 78f
Focal corneal opacities 199
Focal point 3f
Forme fruste keratoconus 66, 167, 207
Fourier analysis
decentration component in 139f
irregularity component in 139f
spherical component in 139f
Fourier transform 137
Foveola 3f
Fuchs’ endothelial dystrophy, diagnosis of 67
G
Geometric tomography 82
Geometrical landmarks 6f
Ghost images 131f
Glare 131f
Globus pattern 69, 69f
H
Halos 131f
Headscarves, tight 152
Height asymmetry, index of 182, 183
Height decentration, index of 183
Herpetic disease 99, 100
Holladay report 207, 208f, 210f
general settings for 30f
specific settings for 25
Hot spot pattern 202f
Hourglass 52
shape 52f
Human eye 129
aberrations 118
optical system of 3
Hybrid devices 12
Hypermetropic correction 195
Hyperopic population 58t
Hyperopic shift 143
Hyperprolate cornea 85f
shape 37f
Hyperprolate surface 83
Hypertrophy 99
I
Image quality control 160
purpose 160
steps 160
Incision, dimensions of 225f
Intereye asymmetry 25, 146, 163
Intereye corneal asymmetry score 153t
Intracorneal rings 67, 191
implantation 199
Intraocular lens 38, 207, 223
aspheric 224
calculation 224
phakic 94
pseudophakic 94
toric 224
types 224
Intraocular pressure 35
Irregular astigmatism 92, 226
intraocular-induced 94
subjective evaluation of 100
suspicion of 100
types of 122
Irregular patterns 57
K
Keratoconic cornea 153, 180f
Keratoconic eye 61, 145f
Keratoconus 105, 167, 177t, 178t, 182, 214, 215f
classification of 177
stages of 178t
index 179, 183
center 183
mild 223
posterior 176
progression 185f190f
suspect 143
with normal thickness 168f
Keratoglobus 168, 172f
Keratometer 36, 41
Keratometric calibration index 38
Keratometric dioptric power 103
Keratometric index 108
Keratometric power
deviation 35
distribution of 22
Keratometry 8
Keratoplasty 96, 131
penetrating 96
Keratorefractive
procedures 94
surgeries, after 41
Keratoscopy 8
K-reading
map, equivalent 212, 214
parameters, equivalent 211
power map, equivalent 41, 211
L
Lamellar keratitis, diffuse 95
Lamellar keratoplasty 97
Laser in situ keratomileusis 41
Laser vision correction 4, 9496, 108, 149, 161, 162, 167, 191, 224
ectasia after 173f
Lens thickness 35
Limbal relaxing incisions 223, 225
M
Map overlay, thickness 23
Mercedes-Benz
image 133f
symbol 129
Meridional power of cornea 104f, 105f
Mesopic pupil, measurement of 108f
Misalignment 23, 148f, 149f
clues of 146
effect of 145, 147f, 148f
patient's error 144
types of 144
Modulation transfer function 119
Multifocal corneal opacities 203
Multifocal intraocular lens 4
Myopia 91
Myopic keratorefractive procedures 83
Myopic population 58t
N
Nasal temporal asymmetry in normal cornea 5f
Nonoptimum spectacle 101
Nonperiodic irregular astigmatism 93, 94f
Numeric scoring systems 153
Numeric values 66
O
Oblate cornea
curvature pattern in 85f
elevation pattern in 85f
Oblate surface 83
Oblique astigmatism 45, 45f, 92
on elevation map 54f
Ocular surgeries, previous 119
Optical axis 3
Optical transfer function 120
P
Pachy apex 34
Pachymetric data 66
Pachymetric progression index 74f, 79
Pachymetry map 67, 196f, 212
Paraectasia 167, 168, 174f, 191
Parallel light rays 117
Patient noncooperation 152
Pellucid marginal degeneration 167, 170f, 218f, 219f
hallmark of 68
Pellucid-like keratoconus 167, 171f, 216f, 217f
Periodic irregular astigmatism 93, 93f
Peripheral extrapolation, mild 22f
Peripheral scar 99f
Phakic intraocular lens 13
Phase transfer function 120
Photokeratoscopy 8
Piston 117, 126f
Placido disk 9f, 10
projection 10f
Placido-based technology 12
Point spread function 119
Post-laser vision correction
corneal irregularities 96
ectasia 168
Post-astigmatic ablation pattern 198f, 199f
Post-corneal-graft 200f, 201f
Post-corneal-rings implantation, patterns of 199
Post-graft pattern 199
Post-hypermetropic
ablation pattern 195f197f
astigmatic ablation 196
laser vision correction 220, 220f, 221f
Postkeratorefractive procedures 41
Post-laser vision correction
patterns 191
study 66
Postmydriatic test 101, 107
Post-myopic
ablation pattern 192f194f
laser vision correction 221, 222f
Power distribution map 107f
Practical subjective scoring system 160, 161
detailed step 161
Prism 127f
Prolate cornea 85f
curvature pattern in 84f
shape 37f
Prolate surface 83
Pterygium 99, 100, 224
bilateral 100f, 101f
Pupil
and thinnest location coordinates 25
center 34
coordinates, unusual 146
zones centered on 211
diameter 35, 208
entrance 3f
size 119
Pupillary axis 3
Q
Quality of capture, checking 23
Quality specification 161f
Quick slope 75f
Q-value
and spherical aberration 37f
negative abnormal 195
R
Radial keratotomy 94, 149
Radius of curvature, anterior 179, 184
Reference surface 51
parameters 52
position 51
principle 51
types of 53, 56f
Refraction
objective 120
subjective 101
Refractive display, four maps 15f
Refractive effect 36
Refractive errors, spherocylindrical 123
Refractive index 38
Refractive map, four-composite 106f, 186f, 187f
Refractive power
map 39
principle and map, anterior 40f
Refractive surgery, previous 223
Regular astigmatism 91, 92f, 137
component in fourier analysis 139f
Relative pachymetry 79, 163
map 191, 192, 193f, 195, 197, 199f, 209, 212, 214
Relative thickness map 79f
abnormal 81f
suspicious 80f
Retinoscopy, irregular reflex on 100
Retrocorneal membrane 97
Rigid gas permeable contact lenses 143
Root mean square 96
S
Salzmann's nodular degeneration 223
Scanning-slit devices 10
Scheimpflug camera 11, 12
lateral rotating 11f, 12f
Scheimpflug corneal imaging 178
Scheimpflug law states 11
Scheimpflug system 11
Scheimpflug-based devices 11
Scissoring reflex 100
Scleral incisions 224f
Screening guidelines 13
Sim-K measurement 8f
Skewed hourglass 153
Spherical aberration 83, 134f
halos resulting from 135f
Spherical component 137
Spherical cornea 84
curvature pattern in 84f
elevation pattern in 85f
shape 36f
Spherical power 182
Spherical surface 83
Starburst 131f
Sturm, interval of 92f
Surface variance, index of 179, 182
Symmetric bowtie inferior steep 153
T
Tangential map, anterior 191, 193f, 198f
Tear film
deficiency 148
disturbance 23, 148
excess 149
Tears on tomography, effect of excess 152f
Testing system, normal noise of 181
Tetrafoil 131, 136f
Thickness map, changes in 145
Tilt 127f
Tissue altered, percent of 67
Tomographers, types of 10
Tomography 11, 12t
Topography 11, 12t
Topometric indices 182
Toxic keratopathy, central 95
Transitional zone 193f
Trefoil 129, 132f
aberration 129, 133f
Trifolium plant 129
V
Vertical asymmetry, index of 183
Videokeratoscopy, computerized 10
Visual acuity 143, 183
best corrected 96
uncorrected distance 143
Visual axis 3
Vortex pattern 49f
W
Wavefront analysis 115
Wavefront and wavefront analysis, principles of 117
Wavefront principle 117f
Wavefront technology, clinical application of 120
With-the-rule astigmatism 44f, 45, 92
on elevation map 53f
Wound-related flattening 226
Wounds, unsutured 226
Z
Zernike analysis 118, 122
Zernike coefficient 120
Zernike polynomials 117, 122
Zernike pyramid 118f, 122
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