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14 Corneal Optical Densitometry display

14 The Corneal Optical Densitometry display,

by Sorcha S. Ní Dhubhghaill, MB, PhD,

Jos J. Rozema, MSc, PhD

Gaining a sense of the structural situation in corneal pathologies can be difficult based on raw
Scheimpflug images alone. For this reason the method of tomographic reconstruction was introduced,
which provides cross-sections along the three cardinal axes. However, as ocular structures often do
not lie within a flat plane, structures at similar depths in the cornea often can appear at different
depths in the tomography, hindering their assessment.
This is where the corneal densitometry screen comes in useful in that it presents scatter data over
a curved plane that is interpolated between the anterior and posterior corneal surfaces. This means
that all structures visible in the map are located at the same relative distance from the corneal
surfaces, making it a useful tool for assessing the depth and position of scattering phenomena that
may occur within the cornea.

What is the clinical utility of corneal densitometry?

If performed in uniform conditions, densitometry assessment can be used for making repeatable,
reproducible measuremements of corneal haze. Densitometry measurements have been used for
following up corneal haze in patients post LASIK or post PRK, or with infectious keratitis, corneal
mucopolusaccharidosis and keratoconus. The scan protocol is simple and does not lengthen the
Pentacam® scan time. We will here describe some of our experiences using this technique.

Applications and Limitations

Any condition that induces a corneal haze or opacity can be objectively assessed using the
densitometry approach, provided that the cornea is not opaque. If the cornea is very hazy or opaque,
the backscatter will be too high and the measurements unreliable. Corneal densitometry also
increases with age in the periphery but remains stable centrally

[30]

.

Note

Densitometry values near the limbus (10 mm – 12 mm from central fixation) should also be
interpreted with caution, as scleral backscatter can artificially elevate the values in this area.

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Содержание Pentacam

Страница 1: ...US Optikger te GmbH Postfach 35549 Wetzlar GERMANY Tel 49 641 2005 0 Fax 49 641 2005 295 E Mail export oculus de www oculus de OCULUS USA info oculususa com OCULUS Asia info oculus hk OCULUS Czechia o...

Страница 2: ...LUS Optikger te GmbH OCULUS has been certified according to DIN EN ISO 13485 and therefore sets high quality standards in the development production quality assurance and servicing of its entire produ...

Страница 3: ...in OD and OS 15 5 2 Form fruste keratoconus 18 6 Fast Screening Report as a first step in examining a patient and evaluating one s findings by Ina Conrad Hengerer MD 20 27 6 1 Case 1 Unilateral high a...

Страница 4: ...ophy with glaucoma by Prof Renato Ambr sio Jr Marcela Q Salom o MD 76 11 5 Screening parameters by Prof Renato Ambr sio Jr 79 12 Belin Ambr sio Enhanced Ectasia Display 80 102 12 1 Why elevation is di...

Страница 5: ...ication time on Pentacam Nucleus Staging PNS by Mehdi Shajari MD Wolfgang Mayer MD Prof Thomas Kohnen 141 142 19 1 Introduction 141 19 2 Case 1 Low PNS and low EPT 142 19 3 Case 2 High PNS and high EP...

Страница 6: ...mileusis in situ by Prof Renato Ambr sio Jr 171 24 Scheimpflug and slit lamp images 173 178 24 1 Corneal dystrophy 173 24 2 Congenital anterior pyramid cataract 174 24 3 Posterior capsular cataract 17...

Страница 7: ...impflug images in three dimensions with the dot matrix fine meshed in the centre due to the rotation It takes a maximum of 2 seconds to generate a complete image of the anterior eye segment Any eye mo...

Страница 8: ...reby taking this effect into account B Inclusion of anterior posterior surface By convention most keratometers use the refractive index of 1 3375 when calculating the dioptric power of the anterior ra...

Страница 9: ...he front and back surface of the cornea however D Location of the principal planes Calculation of corneal power by ray tracing involves sending parallel light through the cornea It must take into acco...

Страница 10: ...g to Snell s law of refraction assuming a refractive index of 1 3375 to convert curvature into refractive power Figure 2 This is a map that other Placido topographers also may show because it only con...

Страница 11: ...r 1 336 as well as the sagittal curvature of each These results are aggregated The True Net Power map thus takes effects A and B into account The underlying equation is Figure 4 True Net Power map cal...

Страница 12: ...map Its output is therefore also referred to as Equivalent Keratometer Readings EKR It calculates power according to Snell s law using the refractive indices of corneal tissue and aqueous humour and a...

Страница 13: ...ncipal planes due to corneal thickness In this way the map takes effects A B C and D into account Its results are more realistic than any other but they will deviate from normal sagittal SimK values s...

Страница 14: ...intended to discourage you from using other maps and settings that you may have found to work best for you 4 1 Recommended settings When working through the following chapters it is advisable to cons...

Страница 15: ...3D pIOL Simulation Software and Aging Prediction prior to iris fixated pIOL implantation available in the Pentacam HR only Calculate the required pIOL power using the implanted calculator Use the dat...

Страница 16: ...lmology Assessment of Corneal Optical Quality for Premium IOLs with Pentacam Highlights of Ophthalmology Vol 39 N 4 2011 Zernike Analysis to determine the amount HOA and LOA ACD manual horizontal whit...

Страница 17: ...and numbers The topographic map Figure 8 shows the left and right eye but gives no unequivocal statement if it is a keratoconus or not The right eye seems to be fine The left eye is a little steeper T...

Страница 18: ...posterior surface indicates this cornea as a suspicious cornea Both sides show an inferior position of the cone with suspicious elevations suspicious elevation Figure 9 4 Maps Selectable showing kerat...

Страница 19: ...more than 30 m Note that the position of the thinning in the pachymetry map and the highest spot on the elevation map are exactly at the same position This is an excellent example to document that top...

Страница 20: ...50 m The anterior and posterior elevation revealed a slightly decentered apex This had led to a false positive inferior steepening on the curvature map Custom LASIK was performed without incident Figu...

Страница 21: ...e showing a form fruste keratoconus false positive topography in OS Figure 13 4 Maps Selectable showing a form fruste keratoconus false positive topography in OD 5 Differences between Placido and elev...

Страница 22: ...degree of nuclear opacity PNS 6 1 Case 1 Unilateral high astigmatism with suspicion of bilateral keratoconus A male patient aged 45 years presented for the first time in 2010 to have his distance spe...

Страница 23: ...wing abnormal pachymetry and elevation data with unambiguous signs of keratoconus in OD Figure 15 Fast Screening Report showing abnormal pachymetry and elevation data with unambiguous signs of keratoc...

Страница 24: ...Figure 16 Belin Ambr sio Enhanced Ectasia Display version III showing keratokonus in OD Figure 17 Belin Ambr sio Enhanced Ectasia Display version III showing keratokonus in OS 6 The Fast Screening Rep...

Страница 25: ...nd transplant deturgenscence was functionally assessed on the basis of the Compare 4 Exams display Figure 18 At one week postoperative central apical corneal thickness measured 670 m In the course of...

Страница 26: ...24 Figure 19 Fast Screening Report showing the presurgical condition in a case of Fuchs dystrophy Figure 20 Fast Screening Report at one month after DMEK surgery 6 The Fast Screening Report...

Страница 27: ...Figure 21 Corneal Optical Densitometry showing the presurgical condition in a case of Fuchs dystrophy Figure 22 Corneal Optical Densitometry at one month after DMEK surgery 6 The Fast Screening Repor...

Страница 28: ...ainst his right eye Analysis based on the Pentacam Fast Screening Report revealed an abnormal value for K Max anterior surface as well as anterior and posterior elevation Figure 23 After calling up th...

Страница 29: ...Maps Refractive with suspicious curvature and elevation maps of the anterior surface Figure 25 Compare 2 Exams showing changes in anterior surface elevation within a period of one week 6 The Fast Scr...

Страница 30: ...r zone from 1 0 to 8 0 mm the Pentacam calculated right eye total cornea refractive power TCRP as having an almost constant astigmatism at around 1 00 1 10 D from the centre up to 5 0 mm peripherally...

Страница 31: ...26 4 Maps Refractive showing with unremarkable elevation maps and curvature map in OD Figure 27 4 Maps Refractive showing unremarkable elevation maps and curvature map in OS 7 Corneal Power Distributi...

Страница 32: ...re 28 Corneal Power Distribution showing normal power distribution in OD Figure 29 Corneal Power Distribution showing a markedly increased power from 2 0 to 3 0 mm in OS 7 Corneal Power Distribution d...

Страница 33: ...g to patient information Uncorrected vision acuity was 20 30 in OD and 20 200 in OS Patient refers severe glare and starburst all day mainly at night OD sph 0 25 cyl 3 00 A 156 VA 20 20 OS sph 5 00 cy...

Страница 34: ...progression in OS The pachymetric progression is abrupt in both eyes providing a significant indication of ectasia Figure 32 Figure 33 Probably mild ectasia could have been diagnosed prior to surgery...

Страница 35: ...terested in further vision enhancement for her dominant right eye Her best spectacle corrected visual acuity BSCVA was 20 20 with sph 1 25 D The referring surgeon was concerned about post LASIK ectasi...

Страница 36: ...This device routinely fails to correctly identify the posterior corneal surface in postoperative patients leading to underestimates of residual bed thickness and frequent incorrect diagnosis of post L...

Страница 37: ...maps incorrectly suggesting ectasia in OD Figure 37 Pentacam 4 Maps Selectable revealing there to be no post LASIK ectasia In this example Orbscan measured the pachymetry 37 microns m thinner than Pen...

Страница 38: ...Examination with the Pentacam 4 Maps Refractive display Figure 38 yielded a corneal thickness of 728 m resulting in a corrected IOP of 11 mmHg according to the Dresdner scale Further examination on t...

Страница 39: ...o of 0 6 in both eyes The lens was clear and gonioscopy examination revealed a narrow angle in both eyes grade I II The anterior segment exam with the Pentacam Figure 41 documented an ACA of 22 5 degr...

Страница 40: ...t in the differential display Figure 43 Figure 42 General Overview display 10 days after YAG laser iridectomy in OS showing improved ACA and ACD values Figure 43 Compare 2 Exams showing changes from b...

Страница 41: ...ct of the treatment evident to her 9 3 Screening for narrow angles by Dilraj S Grewal MD 9 3 1 Case 1 A 64 year old Indian female patient presented for a routine eye exam Her vision was 20 20 in both...

Страница 42: ...aphy OCT and retinal nerve fiber layer RNFL scans showed retinal thickness to be normal in both eyes Figure 49 Figure 45 General Overview display showing a low ACV shallow ACD and narrow angle in OD F...

Страница 43: ...igure 47 24 2 Humphrey visual field full visual field in OD Figure 48 24 2 Humphrey visual field full visual field in OS Figure 49 Spectral domain OCT showingnormal RNFL thickness in both eyes 9 Glauc...

Страница 44: ...year old Indian female patient presented for a routine eye exam Her vision was 20 20 in both eyes She was found to have a shallow anterior chamber on slitlamp biomicroscopy Gonioscopy showed Shaffer s...

Страница 45: ...43 Figure 51 General Overview display showing a low ACV shallow ACD and narrow angle in OS 9 Glaucoma...

Страница 46: ...fects in both eyes Figure 54 Figure 52 24 2 Humphrey visual field showing an early superior arcuate defect in OD Figure 53 24 2 Humphrey visual field showing an early inferior paracentral defect in OS...

Страница 47: ...ng Figure 55 confirmed the diagnosis of phacomorphic glaucoma as evidenced by a shallow ACD of 1 75 mm an ACV of 65 mm3 and ACA of 17 5 degrees in the right eye An anterior vaulting of the lens was vi...

Страница 48: ...46 Figure 56 Scheimpflug Image showing increased ACV deeper ACD and wider ACA following removal of the lens and posterior chamber IOL implantation 9 Glaucoma...

Страница 49: ...6 Show Nasal Temp 7 Show Max Diameter 9mm 12 and Show Numeric Values 14 Anterior elevation posterior elevation Right click on the scale and set to Belin intuitive 75 m for refractive practice Belin in...

Страница 50: ...are considered normal while differences between 12 m and 15 m are suspicious and differences 15 m are typically indicative of keratoconus Similar numbers about 5 m higher apply to posterior elevation...

Страница 51: ...ation island patterns not astigmatism These numbers pertain to elevation in the central and paracentral region in an island pattern 10 2 Normal astigmatic cornea This 4 Maps Selectable display Figure...

Страница 52: ...agittal curvature The curvature maps reveal a steep cornea K1 47 6 K2 50 2 but the elevation maps do not reveal any suspicious areas The pachymetry map is well centered with a thinnest reading of 546...

Страница 53: ...e a similar pattern as does the anterior sagittal curvature The anterior elevation map is symmetric and the curvature shows a symmetric astigmatic pattern The pachymetry map is well centered with a th...

Страница 54: ...re defined astigmatic pattern However because the posterior cornea contributes a much smaller amount to the overall refractive state of the eye the posterior astigmatism reads only 0 4 D in spite of a...

Страница 55: ...astig 0 7 D The anterior elevation shows no defined pattern which is mirrored by the anterior sagittal curvature The corneal thickness is slightly high 583 m in the thinnest reading DIAGNOSIS normal...

Страница 56: ...operties of the posterior cornea no cornea air interface differ from those of the anterior surface the refractive astigmatism of the posterior cornea is listed only as 0 3 D The pachymetry map shows a...

Страница 57: ...on shows a normal astigmatic pattern as does the anterior elevation not shown The pachymetry maps show the thinnest regions OD at 492 m and OS at 483 m This is a normal eye topographically but one tha...

Страница 58: ...or values are within the normal range while the posterior numbers are just outside the normal range The pachymetry map is normal revealing a thick cornea thinnest region 608 m with a normal pachymetry...

Страница 59: ...show an asymmetric pattern Curvature is a reference based measure An asymmetric curvature pattern can occur with a completely normal astigmatic cornea when the apex line of sight and measurement axis...

Страница 60: ...hrough a vertical cross section revealing severe flattening over most of the cornea an inferior band of thinning and a sharp change in corneal contour over the area of thinning PMD is one of the most...

Страница 61: ...pachymetry distribution with a significant inferior temporal displacement of the thinnest zone At times the only indicator of potential pathology may be the magnitude and distribution of the corneal...

Страница 62: ...somewhat irregular astigmatic pattern but without any obvious positive island The tangential curvature incorrectly locates the cone much more inferiorly than the cone location shown by both the poste...

Страница 63: ...nd thinned to 499 m If the surgeon had only relied on anterior curvature and central corneal thickness readings this patient would have been classified as normal normal anterior curvature and central...

Страница 64: ...f the thinnest area towards the area of the abnormal posterior elevation The left eye shows a relatively normal posterior astigmatic pattern but a distinctly abnormal pachymetry distribution with mark...

Страница 65: ...tive deviation maximal at 33 m anterior and 89 m posterior with an accompanying displacement of the pachymetry map thinnest reading 485 m The tangential curvature map also shows inferior steepening bu...

Страница 66: ...in over 10 of normal corneas Corneal tomography provides a three dimensional reconstruction of the cornea thus permitting evaluation of the anterior and posterior corneal surfaces and thereby the cre...

Страница 67: ...in PIT between normal and keratoconic eyes over all locations considered was very high p 0 0001 Keratoconic corneas had a much higher thickness percentage increase than normal eyes on each of the 22...

Страница 68: ...s of our studies served as a basis for engineering new summaries and graphs that would help clinicians explore CTSP and PIT so as to be able to objectively evaluate thickness profiles and detect ectas...

Страница 69: ...corneal thickness for diagnosis and classification of corneal ectasia The CTSP and PIT graphs are furthermore relevant in evaluating abnormal thick corneas in endothelial disease They provide very re...

Страница 70: ...68 Figure 78 Show 2 Exams Pachymetric showing a normal thin cornea Figure 79 Show 2 Exams Topometric showing an ectatic cornea 11 Corneal Thickness...

Страница 71: ...and classification criteria for keratoconus are based on anterior corneal curvature data derived from corneal topography We wish to emphasize that the thickness profile described here should be used...

Страница 72: ...SP and PIT increase sensitivity for the detection of very early forms of keratoconus we studied patients with keratoconus in one eye and in the other a cornea of normal surface curvature as evidenced...

Страница 73: ...ymetric showing a normal cornea Compared with the specificity of artificial intelligence based indices for detecting ectasia topometric indices are fraught with high false positive rates especially in...

Страница 74: ...periphery corneal swelling makes the cornea homogeneously thick decreasing the increase in thickness values towards the periphery We have found that the flattening of the CTSP and PIT curves occurs ev...

Страница 75: ...73 Figure 86 Show 2 Exams Pachymetric showing a case of Fuchs dystrophy 11 Corneal Thickness...

Страница 76: ...gure 88 Scheimpflug image showing clear cornea in OS with no peak in the densitogram for the endothelium 11 3 Case 2 Ocular hypertension by Prof Renato Ambr sio Jr Marcela Q Salom o MD The case below...

Страница 77: ...respectively This is a case of normal thick corneas of correspondingly high stiffness leading to ocular hypertension There is no indication for topical medications to decrease the IOP Figure 90 HRT s...

Страница 78: ...s membrane and the endothelium Camel s sign in both eyes Figure 91 Figure 92 This indicates a less transparent cornea Both lenses can be seen to lack clarity even with non dilated pupils In both eyes...

Страница 79: ...th eyes HRT was not possible in OD due to impaired transparency of the ocular media early cataract and had a below average quality in OS Figure 95 Pascal Dynamic Contour Tonometer IOP measurements wer...

Страница 80: ...guration is abnormal both in the image and according to Moorefield s classification This patient has glaucoma as well Figure 94 Specular microscopy in OD and OS Figure 95 HRT single initial report sho...

Страница 81: ...ge pachymetry progression index 0 8 Fuchs dystrophy or oedema 0 8 average pachymetry progression index 1 2 normal or ocular hypertension average pachymetry progression index 1 2 ectasia The shapes of...

Страница 82: ...troduced a measuring device that included both a magnification and a doubling mechanism enabling the examiner to match the corneal reflection to itself This technique was popularized by Helmholtz in 1...

Страница 83: ...as able to provide a qualitative picture of approximately 50 of the cornea Antonio Placido however who is often credited with this technique was the first to photograph these corneal reflections Placi...

Страница 84: ...t we understand how curvature and elevation measurement differ There is a common misunderstanding in the assumption that curvature maps reflect the shape of the cornea Curvature regardless of how it i...

Страница 85: ...but these will not be discussed here Corneal thickness maps are easy to comprehend Corneal thickness is an absolute measurement representing the distance between the anterior and posterior surface Co...

Страница 86: ...elevation qualitatively useful we need to display the data in a more clinically relevant manner To do this we typically display the elevation data against a non planar reference surface It needs to b...

Страница 87: ...e reference surface to a fixed best fit sphere computed from the central 8 0 mm optical zone setting Manual 8 0 mm Fixing the area used to compute the reference surface is also necessary to allow comp...

Страница 88: ...lly masking the cone A modification of the BFS called the enhanced reference surface utilizes the same 8 0 mm central optical zone but excludes a small portion of this data surrounding the TP on the c...

Страница 89: ...lding an island of greater magnitude The enhanced reference surface is one component of the Belin Ambr sio Enhanced Ectasia Display a comprehensive tool for preoperative refractive surgery screening F...

Страница 90: ...l portion of the cornea from the BFS computation the enhanced reference surface serves to further accentuate ectatic or conical protrusion while having little if any effect on normal corneas The Belin...

Страница 91: ...ata base of normal and keratoconic corneas The major advance is that while an individual parameter s may fall outside the norm the final overall comprehensive reading may still be viewed as normal Fig...

Страница 92: ...l astigmatic pattern The central cornea has a normal thickness at the apex of 532 m but shows little progression towards the periphery causing the PIT tracing to be relatively flat opposite of what yo...

Страница 93: ...t value and TP displacement are all within normal limits The posterior elevation change is further heightened by the enhanced reference surface and the bottom display for the posterior elevation revea...

Страница 94: ...e thinnest value at 568 m is normal The combination of a number of suspicious values however is enough to put the overall reading D well outside of the normal range at 3 23 SD from the norm and it is...

Страница 95: ...phy There are also changes on the posterior surface both yellow more dramatic changes in the pachymetric progression Dp which is red at 3 70 SD from the mean and a mild displacement of the TP yellow T...

Страница 96: ...nown as the enhanced BFS An exclusion map may be significantly different from its corresponding baseline elevation map or it may be very similar depending on the relative impact of the 4 mm exclusion...

Страница 97: ...95 Figure 114 Belin Ambr sio Enhanced Ectasia Display version I showing elevation data on the left and pachymetry data on the right 12 Belin Ambr sio Enhanced Ectasia Display...

Страница 98: ...ic eyes than it is in normals 0 9 0 23 mm p 0 05 Along with the TP the pachymetric display also evaluates the thickness profile of the cornea The basics and interpretation of the CTSP Corneal Thicknes...

Страница 99: ...97 Figure 115 Placido topopraphy in OD showing no keratoconus Figure 116 Placido topography in OS showing no keratoconus 12 Belin Ambr sio Enhanced Ectasia Display...

Страница 100: ...l thickness and anterior curvature The thinnest corneal reading in OS is below 500 m the pachymetric progression graphs are borderline in OD and abnormal in OS and the enhanced elevation maps show cha...

Страница 101: ...99 Figure 118 Belin Ambr sio Enhanced Ectasia Display version I showing subclinical keratoconus in OD 12 Belin Ambr sio Enhanced Ectasia Display...

Страница 102: ...mbr sio Enhanced Ectasia Display improves the ability to detect ectatic disease 7 8 The Ambr sio relational thickness maximum ARTmax 9 was 259 m in both eyes Figure 120 Figure 121 The final deviation...

Страница 103: ...keratoconus in OD Figure 121 Belin Ambr sio Enhanced Ectasia Display version III showing forme fruste keratoconus in OS The Belin Ambr sio Enhanced Ectasia Display shows abnormal values for posterior...

Страница 104: ...be an improvement of the refractive surgery screening process 17 18 However some studies have shown this scoring system to have drawbacks revealing high false positive as well as high false negative...

Страница 105: ...d position of scattering phenomena that may occur within the cornea What is the clinical utility of corneal densitometry If performed in uniform conditions densitometry assessment can be used for maki...

Страница 106: ...the precipitates due to the impossibility of targetingthe endothelial surface with retroillumination Figure 124 Once the patient had been started on a course of antibiotics and corticosteroids he sho...

Страница 107: ...tical Densitometry display showing keratic precipitates after one week of therapy Figure 126 Corneal Optical Densitometry display showing keratic precipitates after two weeks of therapy 14 Corneal Opt...

Страница 108: ...ear old patient with a history of stable keratoconus was treated by implantation of INTACS corneal ring segments The segments are readily visible in the densitometry screen Figure 127 The depth of the...

Страница 109: ...ossible to examine the lamellar interface in greater detail When the visual outcome in the case of this 80 year old lady was slightly less than expected there were found to be specks or deposits of in...

Страница 110: ...sualize the scar its depth in the cornea correlate it to corneal shape topography and its consequent impact on refraction In each and every patient with corneal scarring I begin my quest by using the...

Страница 111: ...op slit lamp images of an on cornea scar Figure 131 General Overview showing findings on an in cornea scar in the Scheimpflug image 15 Using Pentacam technology to evaluate corneal scars planning and...

Страница 112: ...niques but also as a means of educating my patients with a visual aid that they can understand In cases of moderate anatomical abnormality with structural instability i e keratoconus keratoglobus pell...

Страница 113: ...lower 2 images show the impact after Laser PRK following previous INTACS to result in decrease in corneal astigmatism from 3 7 D to 0 3 D After corneal visual rehabilitation collagen cross linking can...

Страница 114: ...measurable After IOL power calculation he then underwent cataract surgery with a precisely calculated lens implant and was brought to emmetropia and unaided 20 20 vision Figure 134 Corneal Optical De...

Страница 115: ...owing a clear cornea following laser scar peel cataract present Figure 137 Slit lamp image showing a clear cornea following laser scar peel cataract present 15 Using Pentacam technology to evaluate co...

Страница 116: ...st cataract surgery with toric lens implant giving 20 20 vision Figure 139 Slit lamp image showing status post cataract surgery with toric lens implant giving 20 20 vision 15 Using Pentacam technology...

Страница 117: ...of lens exchange surgery using a toric lens implant in the second stage which eventually brought the patient to emmetropia and unaided 20 20 vision Figure 140 Corneal Optical Densitometry display afte...

Страница 118: ...he emmetropic outcome after lens exchange surgery INTACS in place Figure 143 Slit lamp image after lens exchange surgery with an emmetropic outcome INTACS in place 15 Using Pentacam technology to eval...

Страница 119: ...as INTACS in the US Anterior corneal curvature analysis showed significant inferior cone displacement and a maximum steepness of 50 D with the steepest part of the cone well below the pupillary margi...

Страница 120: ...s classification based solely on anterior curvature Both the anterior and posterior elevation map as well as the pachymetry map locates the cone just at the inferior pupillary border giving a picture...

Страница 121: ...and high order aberrations HOA Z 4 spherical Z 5 trefoil 5th order Z 6 astigmatism 6th order Figure 147 The keratoconus menu of the Pentacam identifies this cornea as an oblate postoperative cornea N...

Страница 122: ...chymetric showing the pachymetry progression in an oblate postoperative cornea After the implantation of INTACS her visual acuity was OS sph 0 50 cyl 1 25 A 30 VA 20 20 The Scheimpflug image shows a s...

Страница 123: ...thelial EpiON crosslinking using riboflavin 0 22 solution VibeX Xtra Avedro Inc Waltham MS USA The patient was subjected to 8 min of pulsed UV A light 1 sec on 1 sec off at 30 mW cm2 energy dose of 7...

Страница 124: ...122 16 INTACS implantation Figure 151 Preoperative Scheimpflug image of the vertical section Figure 152 Postoperative Scheimpflug image of the vertical section...

Страница 125: ...ious corneal surgery to design a display which contains all of the necessary information for screening treating patients The proper settings for the Holladay Report are automatically set correctly by...

Страница 126: ...tting pull down menu then click Save and check the Lock Settings box Figure 155 shows the map overlay for the corneal thickness map and Figure 156 the overlay for the other 5 maps Figure 154 Miscellan...

Страница 127: ...Medical Optics Santa Ana Calif with a total SA of 0 27 m the Acrysof SN60WF Alcon Inc Fort Worth Texas which is nominally 0 18 m and varies with IOL power and the SofPort AO Bausch Lomb Rochester New...

Страница 128: ...s In general values beyond 2 SD are suspicious of pathology and those beyond 3 SD are considered abnormal statistically The steep red and flat blue semi meridians principal are shown in the 3 mm the 3...

Страница 129: ...nnest pach m m m mean 543 SD 33 509 576 2 SD 67 476 609 3 SD 100 442 643 The central lower map relative pachymetry RP Figure 157 shows why a negative meniscus lens has a predictable thickness from its...

Страница 130: ...Variables indicating shape and SA of cornea front surface Q value Eccentricity Zernike 4 0 SA Seidel Longitudinal SA D 0 54 0 73 Q 2 0 00 0 00 0 26 0 51 Q 2 0 19 1 03 0 00 0 00 0 38 2 10 0 26 0 51 Q 2...

Страница 131: ...l axial radius of curvature mm versus zone diameter red and the mean ring axial radius of curvature mm versus zone diameter green The blue values represent refractive power D of a zone as one moves fr...

Страница 132: ...ues are calculated instantaneously The lower right map Figure 158 shows the EKR power map uses both front and back power Snell s law and represents the values that are appropriate for IOL power calcul...

Страница 133: ...pupil diameter is 5 48 mm and taken with low light levels but depending on the location of the device illuminated room the value is usually smaller than the scotopic pupil size one obtains with infrar...

Страница 134: ...e axial power lines green and red are not and therefore do not reflect actual refractive power changes due to the cornea The distribution of EKR in the 4 5 mm zone shows that the EKR65 mean 40 76 glob...

Страница 135: ...nting in the direction of the hot spot on the curvature maps On the RP map the minimum 4 6 is at the limit of suspicious and is also located at the point of peak power on the tangential curvature map...

Страница 136: ...ry little from 43 02 to 42 63 0 39 D from the 3 to 4 5 mm zone The EKR65 power increases SA as the pupillary diameter increases This visual performance is also affected by KC and is limited by the irr...

Страница 137: ...normal green at the 6 mm diameter The center has a front elevation front is 8 m at the center and on the elevation back is 14 m This elevation on the back is suggestive of ectasia The steepened radiu...

Страница 138: ...priate Ks for IOL calculation would be at the 3 0 mm zone and are EKR65 flat K1 35 23 A 146 and EKR65 steep K2 35 30 A 56 The axes are quite different from the 4 5 mm zone but this is due to the small...

Страница 139: ...taract surgeons to understand the lifestyle of each patient the ocular pathology and the optical quality of the eye before surgery This article explains on the basis of case examples how the Pentacam...

Страница 140: ...ap is used to determine any abnormality in corneal shape In the upper center is the map of Total Corneal Refractive Power TCRP TCRP n 1 376 for cornea n 1 336 for aqueous is calculated from the anteri...

Страница 141: ...nformed consent regarding the effects of corneal irregular astigmatism on quality of vision Total HOA 0 360 m shows mild irregular astigmatism and SA 0 403 m is relatively high but within the normal r...

Страница 142: ...how postoperative refractive errors can be avoided following cataract surgery in post LASIK patients As is well known patients for whom IOL power was calculated by conventional methods often experienc...

Страница 143: ...he software automatically calculates the density of a central 3 dimensional reference block grading it from 0 to 5 During conventional cataract surgery phacoemulsification has to be performed The effe...

Страница 144: ...of 2 99 seconds was calculated 19 3 Case 2 High PNS and high EPT In OD of this caucasian male patient one sees immediately that lens clarity is considerably reduced compared to the first patient This...

Страница 145: ...stigmatism is based on the 1 376 refractive index of cornea whereas the KA is based on the 1 3375 keratometric index which was developed to take into account the influence of the posterior corneal sur...

Страница 146: ...was 20 03 mm and a 33 00 D toric Acrysof Alcon Fort Worth TX was calculated for emmetropia The Pentacam detected a WTRA whose measurements at 3 mm Figure 170 Figure 171 yielded a 0 8 D difference bet...

Страница 147: ...of axial length and corneal power 50 suggested a T4 IOL to correct the KA residual predicted astigmatism 0 23 D 39 and a T3 IOL to correct the TCRP astigmatism residual predicted astigmatism 0 20 D 36...

Страница 148: ...was calculated for emmetropia Traditional KA measurement Figure 172 showed a value of 1 9 161 which was significantly lower than the Pentacam TCRP at 3 mm Figure 173 measuring 2 8 D 160 3 Figure 172...

Страница 149: ...riented at 160 One month after surgery the patient had no residual refractive astigmatism 20 3 Case 3 Cylinder overcorrection from measurement of keratometric astigmatism A 71 year old man underwent c...

Страница 150: ...of 0 2 D 90 we targeted a correction of 1 37 D 76 A SN6AT4 IOL was implanted at 75 One month after surgery the refraction was sph 0 25 cyl 0 25 A 120 Using the KA data would have led to cylinder overc...

Страница 151: ...as Phaco Optics Okulix are linked via interface New algorithm for intraocular lens power calculations after myopic laser in situ keratomileusis based on rotating Scheimpflug camera data Richard Potvin...

Страница 152: ...L The Pentacam allows us to measure very easily and accurately the anterior chamber and so determine if there is enough space to implant an iris fixated Artisan phakic IOL One can measure not only the...

Страница 153: ...A 180 OS sph 0 50 cyl 1 00 A 180 We had a good pre op planning process and a happy post op patient 22 2 3D pIOL Simulation and Aging Prediction by Prof Burkhard Dick Sabine Buchner Optometrist 22 2 1...

Страница 154: ...efore we checked the possibility of a pIOL implantation A 3D simulation of the fit of a pIOL gave a swift answer to this Because of her big pupil size it was clear that only the Artisan Verisyse with...

Страница 155: ...cing the distance between them A possible consequence would be endothelial cell loss a risk that must be taken into account and avoided For this purpose the Pentacam offers unique aging prediction sof...

Страница 156: ...ging by the first impression of her anterior chamber conditions this patient appears suitable for pIOL implantation Without the Pentacam we would have done the implantation However because of the pred...

Страница 157: ...used the Pentacam 3D pIOL Simulation and Aging Prediction to simulate the fit of the pIOL and to check its position over the course of years following surgery using the aging prediction module pIOL l...

Страница 158: ...inimum clearance is 1 mm Conclusion The amount of endothelium cells was in the normal range The patient was young and her refraction could be expected to remain stable over the next year The minimum c...

Страница 159: ...OL and endothelium should be greater than 1 mm Endothelial cell density should be at least 2000 per mm Dislocation of the pupil should be no greater than 1 mm The Scheimpflug image in Figure 183 shows...

Страница 160: ...kic IOL implantation Figure 184 3D pIOL Simulation and Aging Prediction showing a large iris convexity The following warning appears Automatic pIOL alignment may be negatively influenced by large iris...

Страница 161: ...80 sph 14 25 cyl 6 0 A 0 in OS The thinnest pachymetry value was 408 m in OD and 395 m in OS Given the severity of the clinical picture the moderately thin cornea and the presence of contact lens into...

Страница 162: ...ASIK ectasia treated by transepithelial crosslinking followed by phakic intraocular lens implantation in both eyes Figure 186 Scheimpflug Image after transepithelial crosslinking in OD A and OS B slit...

Страница 163: ...act surgery would be the only option to improve her visual acuity She was now presenting at our clinic for a second opinion Scheimpflug imaging was successful Figure 187 in perfectly documenting the p...

Страница 164: ...Pentacam revealed only a small degree of corneal astigmatism Figure 189 but also a peripheral hot spot black circle BSCVA was 20 25 after removing the first sutures The question now was whether also...

Страница 165: ...20 80 in both eyes The Pentacam delivered the solution in two seconds The right eye had a cataract and undetected keratoconus Figure 190 Figure 192 The left eye had no cataract but undetected keratoco...

Страница 166: ...164 23 Case reports from daily practice Figure 193 4 Maps Refractive of OS Figure 194 Pachymetry progression in OS Figure 195 Scheimpflug image of OS...

Страница 167: ...stion open regarding the right eye Which K reading should we use for the IOL calculation The Pentacam gives us an actually measurement ot the central power of the cornea We used 42 9 for both K1 and K...

Страница 168: ...ms had started after wearing her contact lens 6 hours in OS She woke up in the next night with moderate secretion She complained of photophobia and blurred vision in OS when wearing glasses A Pentacam...

Страница 169: ...inolones initiating treatment with an attack dose of one drop every ten minutes during the first hour followed by hourly doses around the clock One day later she reported improvement in her vision as...

Страница 170: ...d female patient presented with incisional edema 12 months after phacoemulsification Endothelial morphology revealed large cells with pleomorphism and polymegathism Central cell count was 1 079 cells...

Страница 171: ...or camel sign over the edematous area on the densitometry This is caused by the high reflectivity of the posterior layer of the cornea at the incision level 23 6 Case 6 Corneal thinning after herpeti...

Страница 172: ...umenting corneal thickness The thinnest spot is displayed in the pachymetry map and can also be seen in the Scheimpflug images facilitating follow up examination Figure 204 The patient was kept on pro...

Страница 173: ...d one re treatment for removal of epithelial ingrowth asked for a second opinion The slit lamp examination Figure 205 revealed epithelial ingrowth under a moderately deep cap reaching the center of th...

Страница 174: ...Maps Refractive confirming epithelial ingrowth The pachymetry map in the 4 Maps Refractive Figure 207 showed this effect as well even in the presence of an opaque cornea The Pentacam was useful for e...

Страница 175: ...p images 24 Scheimpflug and slit lamp images 24 1 Corneal dystrophy Figure 209 Slit lamp photo documenting corneal dystrophy on the posterior surface Figure 208 Scheimpflug image revealing corneal dys...

Страница 176: ...Scheimpflug and slit lamp images 24 2 Congenital anterior pyramid cataract Figure 211 Slit lamp photo showing an anterior pyramid cataract Figure 210 Scheimpflug image showing an anterior pyramid cat...

Страница 177: ...5 24 Scheimpflug and slit lamp images 24 3 Posterior capsular cataract Figure 213 Slit lamp photo showing a posterior capsular cataract Figure 212 Scheimpflug image showing a posterior capsular catara...

Страница 178: ...176 24 Scheimpflug and slit lamp images 24 4 Nuclear cataract Figure 215 Slit lamp photo showing a nuclear cataract Figure 214 Scheimpflug image showing a nuclear cataract...

Страница 179: ...177 24 Scheimpflug and slit lamp images 24 5 Posterior synechia Figure 217 Slit lamp photo showing posterior synechia Figure 216 Scheimpflug image showing posterior synechia...

Страница 180: ...6 Pterygium Figure 219 Topography revealing pterygium Figure 220 Slit lamp photo of an eye with pterygium Figure 218 Scheimpflug image in 190 showing a case of pterygium 24 Scheimpflug and slit lamp...

Страница 181: ...D sph 2 50 OS sph 1 00 The Pentacam Show 2 Exams display showed an optimal eccentricity on the 30 meridian of both eyes namely 0 50 in OD and 0 49 in OS permitting us to propose an orthokeratology tre...

Страница 182: ...atient was examined 4 times within 2 months to follow up the condition of the cornea and the efficacy of the treatment was confirmed by a comparison of all four exams Figure 222 Figure 222 Compare 4 E...

Страница 183: ...rning after wearing the lens over night and in the late afternoon Examination with the Pentacam using the Compare 2 Exams display confirmed that the effect of the ortho K lens was reversed during the...

Страница 184: ...astasios John Kanellopoulos MD George Asimellis PhD J Refract Surg 2014 30 2 88 92 Curvature Analyses of the Corneal Front and Back Surface Bo o Vojnikovi Nikica Gabri Iva Dekaris and Branka Juri Coll...

Страница 185: ...tcome in superficial corneal opacities Mohammad A Rashad Clinical Ophthalmology 2012 6 885 894 2012 Rashad publisher and licensee Dove Medical Press Ltd Corneal Densitometry as an Indicator of Corneal...

Страница 186: ...o P Guerra MD Ricardo Louzada MD Abhijit Sinha Roy PhD Allan Luz MD William J Dupps MD PhD Michael W Belin MD FACS J Refract Surg Posted online July 29 2011 2011 Tomographic Normal Values for Corneal...

Страница 187: ...stics of keratoconus assessed by rotating Scheimpflug imaging Illes Kovacs MD PhD Kata Mihaltz MD Janos Nemeth MD DSc Zoltan Z Nagy MD DSc J Cata ract Refract Surg 2010 36 1101 1106 Q 2010 ASCRS and E...

Страница 188: ...ue Makoto Saika Toshifumi Mihashi Takashi Fujikado Yasuo Tano Investigative Ophthalmology Visual Science June 2009 Vol 50 No 6 Effect of bottle height on the corneal endothelium during phacoemulsifica...

Страница 189: ...onus Eyes Using Scheimpflug Photography Charles R Edmonds O D F A A O Shu Fen Wung Ph D A C N P F A A N Bart Pemberton O D F A A O and Steven Surrett B S Eye Contact Lens 2009 3 120 122 Comparison of...

Страница 190: ...12 040 Comparison between central corneal thickness measurements by Oculus Pentacam and ultrasonic pachymetry Hani S Al Mezaine Saleh A Al Amro Dustan Kangave Abdulkareem Sadaawy Taher A Wehaib Saleh...

Страница 191: ...L Simulation for High Res Imaging This software provides preoperative detection of post operative phakic IOL positioning H BURKHARD DICK MD MANA TEHRANI MD H Burkhard Dick MD J Cataract Refract Surg T...

Страница 192: ...almology 2006 doi 10 1016 j ophtha 2006 01 063 Progress o da espessura corneana do ponto mais fino em dire o ao limbo estudo de uma popula o normal e de portadores de ceratocone para cria o de valores...

Страница 193: ...s Giacomo Savini and Kristian N ser Investigative Ophthalmology Visual Science February 2015 Vol 56 No 2 829 Precision of 5 different keratometry devices Jonas Vejvad N rskov Laursen Peter Jeppesen Th...

Страница 194: ...different measurement technologies Nienke Visser MD Tos T J M Berendschot PhD Frenne Verbakel BSc John de Brabander PhD Rudy M M A Nuijts MD PhD J Cataract Refract Surg 2012 38 1764 1770 Q 2012 ASCRS...

Страница 195: ...e cataract grading by Scheimpflug imaging and effect on operative fluidics and phacoemulsification energy Donald R Nixon MD J Cataract Refract Surg February 2010 Intraocular lens power calculation aft...

Страница 196: ...and Atlas B Dom nech D Mas E Ronda J P rez J Espinosa C Optica Pura Y Aplicada 2009 42 1 51 60 The Comparison of Central and Mean True Net Power Pentacam in Calculating IOL Power After Refractive Surg...

Страница 197: ...ract Refract Surg 2007 33 1041 1044 PIOL Simulation for High Res Imaging This software provides preoperative detection of postope rative phakic IOL positioning H Burghard Dick MD Mana Tehrani MD H Bur...

Страница 198: ...Singh Grewal MD J Cataract Refract Surg 2007 33 116 119 Scheimpflug Imaging in Late Capsular Bag Distention Syndrome After Phacoemulsification Rajeev Jain MS Dilraj Grewal MBBS Rajeev Gupta MS Satinde...

Страница 199: ...heimpflug camera imaging Shuning Li MD PhD Hongtao Wang MD Dapeng Mu MD PhD Jing Fu MD Xiaozhen Wang MD PhD Jian Wang MD PhD and Ningli Wang MD Clinical and Experimental Ophthalmology 2010 38 10 Measu...

Страница 200: ...capsule rupture following closed globe injury Scheimpflug imaging pathogenesis and management D S Grewal R Jain G S Brar S P S Grewal European Journal of Ophthalmology Vol 18 no 2008 Nanophthalmos Ul...

Страница 201: ...ractive surgery Curr Opin Ophthalmol 2013 24 4 310 20 9 Ambrosio R Jr Caiado AL Guerra FP et al Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus J Refract Surg 2011...

Страница 202: ...ation of corneal shape and biomechanics before LASIK Int Ophthalmol Clin 2011 51 2 11 38 28 Ambrosio R Jr Ramos I Faria Correia F Belin MW Tomographic Screening for Ectasia Susceptibility Analysis mus...

Страница 203: ...i G Versaci F Vestri G et al The influence of posterior corneal astigmatism on total corneal astigmatism in eyes with high moderate to high astigmatism J Cataract Refract Surg 2014 40 1645 1653 48 Sav...

Страница 204: ...reening Report showing suspicious values of K Max anterior surface and anterior and posterior elevation 26 Figure 24 4 Maps Refractive with suspicious curvature and elevation maps of the anterior surf...

Страница 205: ...ofile CTSP 64 Figure 76 Thickness profile in an ectatic and a normal eye 66 Figure 77 Show 2 Exams Topometric showing a normal thin cornea 67 Figure 78 Show 2 Exams Pachymetric showing a normal thin c...

Страница 206: ...of the same eye at the patient s initial presentation 104 Figure 125 Corneal Optical Densitometry showing keratic precipitates after one week of therapy 105 Figure 126 Corneal Optical Densitometry sh...

Страница 207: ...f 1 4 D 110 8 144 Figure 171 Corneal Power Distribution display showing a lower amount of astigmatism at 0 6 D 114 9 145 Figure 172 Topometric showing a keratometric astigmatism of 1 9 D 161 146 Figur...

Страница 208: ...o documenting corneal dystrophy on the posterior surface 173 Figure 210 Scheimpflug image showing an anterior pyramid cataract 174 Figure 211 Slit lamp photo showing an anterior pyramid cataract 174 F...

Страница 209: ...N 1243 normal eyes internal unpublished data by J T Holladay 128 Table 7 Back elevation near min RP N 1243 normal eyes internal unpublished data by J T Holladay 128 Table 8 Maximum back elevation N 12...

Страница 210: ...rneal thickness spatial profile cyl cylinder D diopter s EKR EKR65 equivalent keratometer readings equivalent keratometer readings 65 EPT effective phacoemulsification time HRT Heidelberg Retina Tomog...

Страница 211: ...Specification R radius RGPCL rigid gas permeable contact lens RK radial keratotomy RNFL retinal nerve fiber layer RP relative pachymetry SA spherical aberration SD standard deviation sph sphere TCA to...

Страница 212: ...ke University 2351 Erwin Road Durham North Carolina 27705 USA Phone 1 617 584 2334 Fax 1 919 681 6474 Email dilraj gmail com Arun C Gulani MD GULANI VISION INSTITUTE 8075 Gate Parkway W Suite 102 103...

Страница 213: ...de Jos J Rozema MSc PhD Department of Ophthalmology Antwerp University Hospital Wilrijkstraat 10 2650 Edegem Belgium Email Jos Rozema uza be Giacomo Savini MD Studio Oculistico d Azeglio Via d Azegli...

Страница 214: ...212 The following pages remain free and offer space for personal notes...

Страница 215: ...LUS Optikger te GmbH OCULUS has been certified according to DIN EN ISO 13485 and therefore sets high quality standards in the development production quality assurance and servicing of its entire produ...

Страница 216: ...US Optikger te GmbH Postfach 35549 Wetzlar GERMANY Tel 49 641 2005 0 Fax 49 641 2005 295 E Mail export oculus de www oculus de OCULUS USA info oculususa com OCULUS Asia info oculus hk OCULUS Czechia o...

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