Galilei corneal imaging

Scheimpflug imgaging
a wide depth of focus is achieved
 Scheimpflug imgaging differs from conventional techniques in
that the object plane, lens plane, and image plane are not
parallel to each other, but intersect in a common straight line.
 The major advantage is that a wide depth of focus is achieved.

Dual Scheimpflug Imaging
captures slit images from opposite sides of the illuminated slit
 This type of imaging allows assessment of
 anterior and posterior corneal topography,
 anterior chamber depth
 anterior and posterior topography of the lens.
 GALILEI captures slit images from opposite sides of the
illuminated slit, and averages the elevation data
 This Dual Scheimpflug Imaging technique improves the
detection of the posterior corneal surface and provides for
outstanding accuracy in pachymetry across the entire cornea,
even when the camera is decentered due to eye movements

deviation may generate errors in apparent thickness
 Living human eyes are always in motion. In this situation, the
projected slits impinge upon the anterior surface at different
angles, resulting in two apparent slit images representing a
different relative thickness.
 1 mm of deviation may generate errors in apparent thickness of
up to 30 um

Simple averaging of the reduces the decentration error
 Simple averaging (green line) of the thicknesses in the two
corresponding Scheimpflug views (red and blue lines) reduces
the decentration error by a factor of 10

principal advantage
 The dual Scheimpflug imaging principle is independent of
inclined surfaces, and thus allows accurate pachymetry
without knowledge of the actual decentration of the slit
from the apex.

faster single Scheimpflug techqniue
 The Dual Scheimpflug technique is intrinsically faster than
other devices, by requiring only 180° camera rotation
instead of 360° rotation.
 The short recording time makes the GALILEI easy on the
patient, who is not forced to keep the eye open for a
prolonged time.

 Galilei also has a good eye tracker that detects and
compensates for eye movements during image capture.
 it singles out a unique patch on the iris and tracks its
displacement throughout all of the images.This is done on the
x, y, and z axes.
 The Galilei may also add a second iris patch, located on the
opposite side of the iris, to identify and correct cyclotorsional
movement.
faster single Scheimpflug techqniue C good eye-tracker system

high lateral resolution
 lateral resolution is based on a pattern-matching algorithm
 For most diagnostic examinations, the standard acquisition
resolution is 15 scannings on 360º of the cornea and one
Scheimpflug acquisition on each 24° of camera rotation.
 With the Galilei, it is possible to increase this resolutions of
between six and 60 acquisitions (ie, one acquisition from 60° to 6°
of the camera’s rotation)
 Therefore, the variety of resolutions provides us with more precise
anterior and posterior elevation.

Galilei
optical density
 The Galilei also integrates a new diagnostic tool into its profile:
optical densitometry.
 this tool deciphers the patient’s degree of corneal opacity by
calculating the intensity of the incident and transmitted rays.
 The Galilei is the only tool to measure and control the optical
density in two distinct manners, meaning it measures in a the x
and y axes.
 you can control each image by filtering its color . This function
allows the surgeon to zoom in on corneal images, thus observing
any changes in the corneal opacities

Galilei
Placido Topography
 Geometric analysis of the shape of the reflected rings permits
to calculate the steepness, or curvature, of any given point on
the corneal surface, and hence to construct a curvature map.

 The specific benefit of Placido topography is that it is
capable of accurately determining central anterior corneal
curvature; a task that is difficult for a Scheimpflug system
 One major shortcoming of Placido topography is that it is
measuring reflections on the surface of the cornea only.
Therefore the method is not capable of detecting
information about the thickness of the cornea.
Placido Topography determining central anterior corneal curvature

merging Placido and Scheimpflug data
 GALILEI™ overcomes this limitation by merging Placido
and Scheimpflug data, acquired simultaneously by the
two techniques, into a comprehensive single data set.
This is essential for obtaining highest accuracy for both
elevation and curvature data across the entire cornea.
 In comparison, the Orbscan has approximately 9,000
data points to the Galilei’s approximately 122,000 points.

unique features
 GALILEI incorporates the following unique features:
 Merging of Placido and Scheimpflug Data
○ Provides for high accuracy for both elevation & curvature data over
the entire corneal surface.
 Near/Far adjustable Fixation Target
○ Allows examining the anterior chamber, crystalline lens, and any
implants under near and far accommodation.
 Eye Motion Correction
○ The motion of the eye is tracked based on iris pattern recognition
and corrected for to prevent motion artifacts.

Map interpretation
Refractive report
 The basic Refractive Report contains the four standard maps that are
displayed by other tomographers. These maps include
 Anterior Axial Curvature,
 Pachymetry,
 Anterior Elevation and
 Posterior Elevation (BFS)

Map interpretation
Default and alternate profile
 The Default Profile uses one default distribution of colors for all
mapst that available in all GALILEI units in former versions
 The Alternate Profile was optimized to use the best available scale
for each magnitude and incorporates the universal meaning of
traffic light colors for all maps
 Although the same data are used to produce maps of both profiles,
the map patterns and colors may look different due to the scales
used.
 Numerical values are shown only in the Alternate Profile and could
be displayed on all maps.

The appearance of a yellow region indicates that the surface curvature is on the border-line of being abnormally steep and any
orange region indicates that the surface has already an abnormally steep curvature.

Map interpretation
The Anterior Axial Curvature map
 The Default Profile is presented with the Default Type I 1.5 D color scale
 The Alternate Profile with the Default CGA 1 D color scale and is calculated with
a keratometric refractive index of 1.3375
 There are reasons why Anterior Axial maps with one diopter (D) scale are
recommended and easier to understand.
 First, it is faster and simpler to count color steps one-by-one in 1 D increments
 Second, larger steps (1.5 D) may mask typical patterns of asymmetry and astigmatism.
 Third, vertical or horizontal asymmetries larger than 1.4 D are usually considered risk
factors for refractive surgery.
 Since the GALILEI CGA 1 D color scale has 6 green steps ranging from 41 D to 46
D, any asymmetry larger than 1 D will be evident. Yellow region indicates is on the
border-line of being abnormally steep and any orange region indicates an
abnormally steep curvature.

Map interpretation
Pachymetry map
 The Default Profile use Default Type II 25 scale and ANSI Type III
10 µm but Alternate Profile use German CGA 20 µm scale that is
much better
 the thickness progression and distribution are more apparent
when the yellow step is located in the middle of the color scale
 The German style has 15 thicker steps of 20 µm each instead of
only 11 steps as displayed with the Default style.

Map interpretation
Anterior and Posterior BFS Elevation maps
 Normal maximum peak of
 Anterior Elevation BFS should be less than 10-12 µm and of the
 Posterior Elevation BFS should be less than 15-16 µm)..
 To facilitate map interpretation, the Alternate profile
provides
 3 greensteps show the normal ± 5 µm values and
 2 yellowsteps to indicate border- line values.

Map interpretation
Indices displayed with the refractive repor
 The indices are presented in mm and diopters
 The average SimK values, K Steep, K Flat and steeper Astigmatism with angle are
calculated and displayed at the top.
 Anterior Instantaneous axial curvature (range: 41 D to 47 D)
 Posterior axial curvature (range: -5.50 D to -6.8 D).
 Eccentricity (€) value(corneal shape)
○ Normal corneal surfaces vary from a sphere (€2 = 0) to a prolate toric ellipsoid
asphere (+1 > €2 > 0).
○ The anterior surface (mean value €2 = +0.20 ± 0.16) is less prolate than the
posterior surface (posterior €2 > anterior € 2)
○ it seems there are no normal untouched corneas with € 2 < 0 or € 2 ≥ +1

 The mean Total Corneal Power (TCP) by ray tracing, TCP steep, TCP flat
and steeper Astigmatism with angle
 The Axial Anterior Curvature in diopters calculated with a 1.3375
refractive index
 Corneal thickness averages ,the thinnest point thickness and location;
 pupil size and location of pupil center, and the
 limbus-to-limbus distance from Superior-Inferior and Temporal-Nasal.
Map interpretation
Indices displayed with the refractive repor

 The Refractive Report is the most commonly map used
 However may be insufficient for some cases because it compares ante and post corneal
surfaces using only BFS elevation map and the posterior surface curvature map is not
shown in this popular report
 For this reason suggest reviewing routine cases using two separate reports.
 A new customized report containing the curvature and elevation topography of
both anterior and posterior corneal surfaces
 A second report using the Map x1 option and containing only the pachymetry map

Evaluation of refractive report
Normal Spherical Cornea
 There is an anterior axial curvature map
without a bow-tie pattern (0.22 D of
astigmatism and €2 = 0.09) that tends to
blue because the surface is uniformly flat
(SimK Avg 41.09 D).
 The thinnest thickness value is 560 µm and
there is asymmetric thickening of the
peripheral cornea well observed by the
change of color from green to blue (more
nasal blue steps than temporal).
 There is an almost completely green
anterior BFS map as should be expected
when the surface uniformly fits the same
radius of best fit sphere (±5 µm).
 The normal green horizontal bridge
pattern on the posterior BFS map suggests
that the posterior surface is toric, prolate
and elliptical (the indices report 0.25 D of
astigmatism and €2 = 0.29).

normal astigmatic cornea
 A normal anterior prolate elliptical surface (€2 =
0.31) with a typical steeper vertical (warmer)
bow-tie representing a 1.5 D with-the-rule
astigmatism.
 A completely green pachymetry map indicating a
normal thickness distribution and there is a
normal symmetric thickness progression (fewer
than 10 steps of 20 µm per step).
 A normal horizontal green bridge pattern is in
the anterior BFS map
 The posterior surface is also elliptical but more
prolate (€2 = 0.72) than the anterior surface.
 The posterior BFS map also shows a normal
horizontal bridge pattern with a yellow “hot
zone” at the temporal side.
 When these hot zones are temporal or nasal,
it usually announces an asymmetric bow-tie
(irregular astigmatism) in the respective
curvature maps When they are located at the
center of the bridge, they may correlate with
steeper curvatures

KC with Irregular Astigmatism
 an irregular with-the-rule astigmatism in both
the ante and post surfaces
 very asymmetric vertical bow-tie appearance
 inferior steepening of more than 52 D and a
superior flattening less than 40 D
 Both anterior and posterior surfaces (€2 = 1.17
and €2 = 1.23, respectively) are prolate with an
asymmetric hyperbolic shape (€2 > 1.0). e)
 CCT is 471 µm and the thinnest point is 467 µm
 The thinnest point is located 0.8 mm from the
pupil centroid
 an abnormal central hot zone in both BFS
elevation maps achieving almost 20 µm in the
anterior and 30 µm in the posterior surface.

Map interpretation
keratoconus report
 Keratoconus Report inclue
 Anterior Instantaneous (tangential) Curvature map.
 Pachymetry
 Anterior Elevation map
 Posterior Elevation (BFS)map

Map interpretation
Instantaneous map of keratoconus report (Alternate and default )
 In the Alternate Profile This Instantaneous map is calculated with
the keratometric refractive index of 1.3375 and is displayed with the
Default CGA 1.5 D scale.
 In the Default Profile it is shown with the Default Type I 1.5 D scale.

Map interpretation
Instantaneous map keratoconus indices
 The numerical indices of axial curvature and indices,
 The Inferior-Superior (I-S) index (an I-S index >1.20 is considered a risk factor
 The Standard Deviation of Corneal Power (SDP) are often increased in KC.
 The Keratoconus Prediction Index (KPI) is a compilation index that simulates the
percent probability of KC based on the anterior surface analysis
○ KPI from 0 to 10% seems to correspond to normal or suspicious corneas;
○ KPI from 10 to 20% to suspicious or borderline keratoconic corneas;
○ KPI from 20 to 30 % to keratoconic or perhaps still suspicious corneas, and
○ KPI more than 30% should be considered pellucid marginal degeneration (PMD) or KC
 The Keratoconus Probability (KProb) refers to a specificity and sensitivity validation of
the reported KPI value based on the statistical analysis of a series of normal corneas
and corneas with KC

 The keratoconus prediction index is a compilation index of DSI, OSI, CSI, SAI, SimK1, SimK2, IAI, and AA.
 The Keratoconus Probability (Kprob) is the probability that a keratoconic pattern was correctly detected, based
on anterior surface axial curvature. Kprob was calculated based on GALILEI data from a unique database of
clinically diagnosed normal and Keratoconus patients.
 The Cone Location Magnitude Index (CLMI) is detected on the anterior axial curvature map using a 2 mm spot
to search a total search zone of 8 mm diameter. To activate CLMI on the map, make a right-click on the anterior
curvature map and tick “CLMI”. The CLMI location will appear as a circle directly on the map. The corresponding
value is always displayed in the Keratoconus indices section as CLMI aa.
 Percent Probability of Keratoconus (PPK) is defined as the optimal probability threshold for the detection of the
disease, based on CLMI. The “suspect” range limits are 20% < PPK < 45%, where PPK > 45% has a high
probability of Keratoconus.
 Area Analyzed (AA) The simulated index is the ratio of the actual data area to the area circumscribed by a circle
4.0 mm in radius. It is a percentage value equaling 100% if the area is completely covered with measurement
values.
 Average Central Power (ACP) ACP is simulated as the average dioptric power of all points within the central 3
mm.
 Central/Surround Index (CSI) The simulated center/surround index reports the difference between the average
area-corrected power between the central area (3-mm diameter) and an annulus surrounding the central area
(3–6 mm).
 Differential Sector Index (DSI)The simulated differential sector index reports the greatest difference in
average area-corrected power between any two 45° sect

 Irregular Astigmatism Index (IAI) is simulated as the average summation of area-corrected dioptric
variations along every semi-meridian for the entire analyzed surface and normalized by the average
corneal power and number of all measured points. The mathematical description of the simulated IAI index
is:
 Inferior-Superior (I-S) is simulated as the difference between the inferior and superior average dioptric values
approximately 3 mm peripheral to the corneal vertex as defined by the center of the map.
 Opposite Sector Index (OSI) The simulated opposite sector index reports the greatest difference in average
area-corrected power between opposite 45° sectors.
 Surface Asymmetry Index (SAI) is simulated as the centrally weighted average of the summation of
differences in corneal power between corresponding points 180° apart on all meridians.
 Standard Deviation Powers (SDP) is simulated as the standard deviation of all measured powers present on
the map.
 Surface Regularity Index (SRI) index is simulated as a difference in power gradient between successive points
on a hemi meridian that is assigned a positive value and added to the running sum. This sum is divided by
the number of points that went into the sum and then scaled. The mathematical formula of the simulated SRI
index is:

Evaluation of Keratoconus reports
Normal Spherical Cornea
 I-S index is 0.61 D indicating a
small asymmetry within normal
range.
 SDP is only 0.36
 SRI is 0.41 D suggesting a regular
and spherical anterior surface.
 ACP is 40.99 D confirming the
tendency towards a flat surface.
 The KPI is 0%.

Astigmatic Cornea With Initial Posterior Surface Changes
 A “D-shaped” pattern in the
horizontal meridian that has
been reported as a risk factor
for ectasia
 I-S index is 1.29 D also
indicating some inferior-
superior asymmetry.
 The SDP index is 0.91 D,
 SRI is 0.93 D,
 ACP is 43.87 D and
 KPI is 0.9%

KC with Irregular Astigmatism
 more than 54 D of inferior
steepening and less than 36 D
of superior flattening (≈ 18 D
of diop-tric difference).
 The I-S index is 10.18 D
 The SDP index is 3.67 D,
 SRI is 1.81 D,
 ACP is 47 .62 D
 KPI is 100%

Galilei and IOL power calculation
anterio and posterior corneal power measurment

Map interpretation
The IOL Power report
 The IOL Power report include 4 map
 Anterior Axial curvature map
 Total Corneal Power map
 Total Wavefront HOA map
 Placido ring pattern
 This report shows all indices including
 SimK ,SimKavg , astigmatism
 Total Corneal Power
 RMS HOA
 SA (spherical aberation)
 ACD (from the corneal endothelium )
 Anterior chamber volume
 Chamber angles in degrees at the superior, temporal, inferior and nasal direction,
 Nasal-temporal (horizontal) and superior-inferior (vertical) limbus diameter,
 Pupil diameter (approximately mesopic) and the Cartesian location of the pupil centroid
relative to the center of the map.
 The average anterior segment length (ASL) or distance to the posterior lens requires
measurement with a dilated pupil.

 The most important value in this window is the 4-mm central
average Total Corneal Power (TCP).
 The TCP is calculated by ray tracing the refractive power of the
cornea using the anterior surface, the pachymetry and the
posterior surface
 The equivalent power of the cornea (thick lens formula) is the
addition of the anterior and posterior curvatures including the
ratio thickness/ refractive index of the cornea
Map interpretation
The IOL Power report ( Total corneal power )

anterio and posterior corneal power measurment
 Anterior cornea power measurment precision
 The surgeon must remember two relationships:
 0.1 mm of error in anterior curvature radius translates into 0.65 D of error in
simulated keratometry (SimK), and
 1.00 D of error in keratometry becomes 1.00 D of error in pseudophakic refraction
 Posterior corneal power measurment precision
 can be calculated from the anterior radius using the value 1.3375, or the standard
index of refraction.
 Total corneal power measurment precision
 keratometers and topographers calculate SimK, represents the average of total
central power, just measuring the anterior surface.
 It has been known for a long time that this number overestimates the true corneal
power.

main biass: Anterior-to-posterior radii ratio is constant
 More accurate SimK calculations may be obtained using other index
of refraction values, such as 1.3315 or 1.333, both of which have been
tried in the literature.
 The 1.3375 value has worked well for contact lens adaptation and
IOL power calculations because this inaccuracy, being systematic,
can be corrected by compensating for the bias.
 However, the Achilles heel of this calculation is that it is based upon
one main assumption: Anterior-to-posterior radii ratio is constant
 This means that the steepness of the posterior cornea is
proportional to the anterior cornea, with a normal value of around
1.21. Any cornea with a different ratio will make the SimK
calculation with an arbitrary index of refraction erroneous.

 In the last couple of years, we have seen many corneas that have an
abnormal ratio.
 After myopic LASIK or PRK, the anterior radius of curvature becomes higher
(flatter), and the posterior radius remains unchanged, thus increasing the
anterior-to-posterior ratio value.
 After radial kera-totomy, the ratio increases in a lower magnitude, because
there is some posterior flattening as well.
 After hyperopic corneal surgery, the change is opposite, and the ratio
decreases.
 In irregular corneas (eg, keratoconus, scars), the ratio can change as well.
main biass: Anterior-to-posterior radii ratio is constant

 Once both radii are known, ray tracing can be performed to
determine the optical properties of that cornea. Paraxial calculations
can give a simple central power value, and more complex exact
calculations can display lower- and higher order aberrations of the
total cornea.
 The Galilei performs precise measurement of the posterior cornea,
with a high repeatability index of 0.11 D using the Bland-Altman
coefficient. It shows a similar value before and after corneal refractive
surgery.
 Moreover, the software calculates total central power by means of
raytracing and algorithms that predict pseudophakic anterior
chamber depth
Galilei performs precise measurement of the posterior cornea

The Galilei predicts IOL power for normal patients as well as the IOLMaster do

The GALILEI G6 Lens Professional
The Advantages of an All-in-One System

The GALILEI G6 Lens Professional
The Advantages of an All-in-One System
 The GALILEI G6 Lens Professional* (Ziemer Ophthalmic Systems AG) is
advantageous to use for preoperative screening of cataract patients as well as
refractive surgery candidates because it encompasses both corneal tomography
and an optical biometer in a single devic
 Convenience. the patient no longer has to move between several machines.
 Cost. Additional machines are no longer required
 Physical space., freeing up space for other uses.
 Functionality. The GALILEI enables to perform corneal tomography, wavefront
analysis, pachymetry, and biometry for different purposes, including standard
cataract surgery, cataract surgery with toric IOL implantation, planning limbal
relaxing incisions (LRIs), and LASIK

The GALILEI G6 for Subclinical Keratoconus
Automated Detection Program

The GALILEI G6 for Subclinical Keratoconus
 an automated screening program based on artificial intelligence for improving
the sensitivity of subclinical keratoconus detection.
 One of the major advantages of this decision-tree classification method is its ease
of interpretation and of understanding
 Automated decision tree, generated to discriminate between normal corneas and
those with forme fruste keratoconus. The discriminating rule includes the
posterior asphericity asymmetry index (AAI) and the corneal volume.

The GALILEI G6 for Subclinica Keratoconus
This index is calculated over the best-fit toric and
aspheric (BFTA) reference surface, which was recently
shown to improve the sensitivity of subclinical
keratoconus detection when compared with the
elevation analysis over the classical best fit sphere (BFS.)

GALILEI image that shows the suspect
anterior instantaneous curvature and
posterior best sphere elevation map
GALILEI image that shows the
abnormal posterior best fit toric asphere
elevation map (AAI = 24 µm)

GALILEI images that show the clear keratoconus throughout the left
eye (A, B) and especially when viewing the posterior best fit toric
asphere elevation map (AAI = 100 µm).

)
The GALILEI G6 for
Avoiding Visual Complaints With Premium IOLs

The GALILEI G6 for
Avoiding Visual Complaints With Premium IOLs(Asheric IOL)
 Spherical Aberration
 Average corneal surfaces a Q factor (Є2) around 0.00 and spherical aberration
between 0.25 to 0.30 µm .The Є2 is an index of corneal surface shape and
correlates well with the total corneal spherical aberration
 In normal aspheric ellipsoid prolate cornea, - Q or + Є2 increase and the
corneal spherical aberration becomes less positive (µm).
 Ideally, aspheric corneas with anterior Є2 around 0.60 have 0.00 µm of
spherical aberration;after laser refractive surgery
○ hyperprolate corneas with higher anterior Є2 have negative spherical aberration.
○ oblate cornea with lower Є2 have positive spherical aberration
 After cataract surgery, the total spherical aberration is the sum of the corneal
spherical aberration and the IOL’s spherical aberration.
○ Therefore, the preoperative total corneal spherical aberration can be used to select
the best spherical or aspheric IOL in accordance to what the practitioner decides is
best for the eye after cataract surgery

The Kranemann-Arce Index is the quantitative index of asymmetry of corneal
surface shape and may be assessed in the BFTA maps of the GALILEI.
The GALILEI G6 for

Suggested decision tree for the selection of IOLs according to the corneal
surface shape and the total corneal spherical aberration.
The GALILEI G6 for

The GALILEI G6 for
Avoiding Visual Complaints With Premium IOLs(multifocal and toric IOL)
 Coma aberration
 An asymmetric corneal surface shape correlates well with the total corneal
coma , which is the induced starlike dispersion of light rays not focused at
the optical axis causing a variation in magnification over the entrance pupil
 Large kappa distance or misaligned aspheric IOLs tend to induce increased
coma that may be clinically significant in patients who receive a multifocal
IOL.
 Increased K-A index and coma have been linked with visual complaints in
patients with keratoconus and after implantation of toric, aspheric
monofocal, or multifocal IOLs.

 (Restor,Tecnis) should not be implanted in eyes
 with vertical or horizontal total corneal >than ±0.50 µm and
 kappa distance > 0.45 mm
 (Rezoom) would be contraindicated in eyes with
 kappa distance > 0.75 mm
 Better results with toric IOLs have been observed when coma is
parallel or 90° from the steepest axis of astigmatism. Ideal eyes
for toric IOL implantation are those with a symmetric corneal
shape and little coma
The GALILEI G6 for

 Trefoil, Quatrefoil, And Other HO
 Increased abnormal trefoil and quatrefoil correspond well with wavy shape of
wavefrontthat commonly found in corneas that have previously undergone
radial keratotomy, penetrating or lamellar keratoplasty; those with asymmetric
keratoconus, pellucid marginal degeneration, or postoperative ectasia
 presently recommend not to implant multifocal IOLs when a
○ cornea has >+2.00 SD of HOAs.
 In the presence of
○ >±0.50 µm of coma,
○ >±0.40 µm of trefoil,
○ >±0.30 µm of quatrefoil, and
○ >±0.20 µm of fifth-order aberrations,
toric and multifocal IOLs should probably not be implanted
The GALILEI G6 for

The GALILEI
Total Corneal Astigmatism for Toric IOLs
 The posterior cornea, in almost every case, is steep vertically.
 Because the posterior cornea is a minus lens, that vertical steepness creates refractive
astigmatism that is against-the-rule, meaning the corneal power is greater along the
horizontal meridian.
 The GALILEI is designed to help surgeons more accurately select the toric IOL and
prevent what is commonly occurring:
 over-correcting eyes that have with-the-rule astigmatism and
 under-correcting eyes that have against-the rule astigmatism
 GALILEI will enable us to measure the posterior corneal curvature
before surgery and, in so doing, we will be able to get a comprehensive measurement
of total corneal astigmatism.
 This will allow us to select our toric IOL appropriately based solely on that have
against-the-rule astigmatism

In this case, the SimK astigmatism (from the anterior cornea) was 2.88 D @ 85°, the posterior corneal astigmatism was -0.63 D
@ 88°, and the total corneal astigmatism was 2.59 D @ 84°. Based on anterior corneal measurements only, one might select an
IOL that corrects at least 2.50 D of astigmatism. Knowing that the posterior cornea contributed more than 0.50 D of an against-
the-rule refractive effect, a toric IOL that corrected 2.00 D of astigmatism was implanted. At 3 weeks postoperatively, the
manifest refraction was plano.
The GALILEI
Total Corneal Astigmatism for Toric IOLs

Galilei corneal imaging

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