Reading Pentacam Topography (Basics and Case Study Series) Mazen M Sinjab
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1Step by Step® Reading Pentacam Topography2
3Step by Step® Reading Pentacam Topography (Basics and Case Study Series)
Second Edition
Mazen M Sinjab MD MBBCH MSc CABOphth PhD Professor of Ophthalmology Damascus University Damascus, Syria Senior Consultant in Anterior Segment and Refractive Surgery Senior Consultant in Oculoplastic Surgery Damascus University Damascus, Syria Dr Haifa Eye Hospital Bahrain Foreword Arthur B Cummings
4
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Step by Step® Reading Pentacam Topography (Basics and Case Study Series)
First Edition: 2010
Second Edition: 2015
9789351523970
Printed at
5Dedicated to
My wounded country Syria All the rebellious people who are seeking freedom in this biased world The martyrs who irrigate homeland by their blood for us to live free
My dear father Mohamad (may God rest his soul), who implanted in my soul the love of excellence (I will mention his name with my name all my life)
My mother Almasah (may God rest her soul), who implanted in my heart the love for the poor and for helping others
My wife Ruba (may God save her), whose unwavering support was critical for this book.
6
7Foreword
This is the second edition of Mazen Sinjab's highly successful book titled Step by Step Reading Pentacam Topography that was first published in 2010. The author has published five books thus far and is in the process of publishing more. He has the gift of making complicated matters simple and this is another example of that special talent. Having written many articles over the years and presented instructional courses on the subject of understanding and interpreting corneal topography, it was a natural progression to publish his knowledge in textbook format. Mazen has published many articles on corneal topography in the Cataract and Refractive Surgery Today (CRST, Europe) monthly journal and this particular journal has a monthly ranking of the most popular articles. Each time that this author submits an article, it ranks in the top five articles. The major factors contributing to the popularity of the articles are the systematic methodology applied to the material and the fact that his writing appeals to all levels of experience from the most advanced ophthalmologist to the new trainee. All will find Mazen's article helpful. Most of Mazen's articles and books share a common recipe, namely of presenting the material in a manner that relates to clinical practice and has practical relevance for the reader. Clinical interpretation is taught and his teaching is typically illustrated with case-studies. These factors combine to give the reader a meaningful and lasting insight into the topic at hand. Instead of giving the reader a fish, he provides the reader with a fishing rod and the tools to develop their own skills to interpret corneal topography.
Corneal topography initially gained prominence in the sphere of refractive surgery for the main purpose of excluding potential candidates for RK or LASIK due to sub-clinical keratoconus. As technology developed, corneal topography developed into a therapeutic corneal tool when the data was used to drive 8topography-guided photorefractive keratectomy (PRK). The excellent outcomes in these complicated cases underline the power of corneal topography maps and the significance of understanding them. Modern cataract surgery has evolved into refractive surgery and now topography interpretation is an important part of understanding intraocular lens choice for lens replacement in cataract and clear lens extraction surgery. Multifocal IOLs would be contraindicated in a patient with irregular corneal topography that may present with normal Ks on keratometry. Likewise, good decisions can be made in terms of toric IOL selection using corneal topography.
In this book, the comparison made among the three most popular diagnostic devices in chapter one is of most importance; it informs the reader about the principles in general and specifically. Chapter two presents all the required details of corneal topography/tomography in terms of shapes and parameters related to their clinical application. Although very comprehensive, they are presented in a simple way that is easy to understand and memorize. In chapter three, a systematic methodology is presented to guide the reader in reading, interpreting and scoring refractive surgery cases in a step-by-step approach. This approach is important since it trains readers not to miss any information available to them. Chapter four presents a thorough clinical approach of the refractive surgery candidate. The importance here stems from its relevance to the systematic methodology to study the case as a whole. Chapter five mentions some of the major rules and recommendations in refractive surgery, which are used in studying the cases presented in chapter six. Since this book concentrates on corneal topography and tomography, not all rules and recommendations are mentioned in this book. Readers can find them in the recently published book by the same author titled‘Five Steps to Start Your Refractive Surgery’. Finally, chapter six is devoted to using all the previously acquired information and to apply systematic methodology to six diverse cases in order to refine diagnostic skills.9
Improving your understanding of corneal topography/tomography and its interpretation and clinical application is an excellent start on the pathway to making your cataract and refractive surgeries more successful and your patients more satisfied with their surgery. Many of our patients will have Dr Mazen Sinjab to thank for this.
Arthur B Cummings mb chb fcs(sa) mmed(ophth) frcs(edin)
Consultant Ophthalmologist
Wellington Eye Clinic and Beacon Hospital
Dublin, Ireland10
11Preface to the Second Edition
Skillful interpretation of corneal imaging is a key to successful refractive surgery. Since the introduction of topography to ophthalmology, great advances in corneal imaging technology have been achieved, new terminology such as tomography has been introduced and new concepts are being added. All these factors resulted in better understanding of corneal characteristics.
The aim of this book is to correlate the basics of corneal topography and tomography to clinical practice by following systematic clinical interpretation.
A systematic way is followed to build streamlined chapters of the book. Chapter one: Devices to Measure the Corneal Surface gives an introduction to imaging devices concentrating on Pentacam, Sirius and Galilei. Chapter two: Corneal Topography and Corneal Tomography discusses corneal topography and corneal tomography in detail. In chapter three: Reading Corneal Tomography, the systematic methodology was introduced. To give a full picture, corneal imaging was supported with thorough clinical approach of the candidate for refractive surgery in chapter four, Rules and recommendations in refractive surgery are discussed in chapter five. Following these five chapters, the streamlined method is addressed in chapter six, which includes clinical cases studied by applying the systematic methodology.
There are sure to be some errors. As the ophthalmology editor, I take the full responsibility for these and look forward to being further educated.
Mazen M Sinjab12
13Preface to the First Edition
Taking the right decision in laser refractive surgery depends to a great extent on good reading of corneal topography and its clinical interpretation. This is very important for having the aimed results and avoiding postoperative complications.
Data in this book were obtained and gathered from the user manual of the Pentacam, international conferences, refractive journals, personal contacts with many refractive professors and, of course, self-experience.
The strategy in compiling this little book is making a quick refreshment of what has been explained in the previous book “Corneal Topography in Clinical Practice” published by Jaypee Brothers Medical Publishers (P) Ltd, and then follows a systematic approach of topographical pictures in chosen cases. This strategy allows the readers to qualify and quantify any case in the future in a way that no data may be lost.
There are sure to be some errors. As the ophthalmology editor, I take the full responsibility for these and look forward to being further educated.
Mazen M Sinjab14
15Acknowledgments
I am very grateful to Al Zahra Eye Centre, Damascus, Syria for providing me with all the Pentacam images, and to Dr Haifa Eye Hospital, Manama, Bahrain for providing me with all the Sirius images.
I would like to record my continuing debt to the many colleagues and friends who have encouraged me over the years to write the first edition in 2010, and to come up with this updated second edition, which has been extensively written and much has been changed.
I will never forget my students in Damascus University, Syria, who were and are still my spiritual motivators, and as I have learnt, teaching is a circle and those who are being taught also contribute to the subject and to their teachers.
Finally, I am certainly indebted to my readers, who love my way in writing and without whose encouragement, this second edition would never have been written.
19Abbreviations AB/IS:
Asymmetric bowtie-inferior steep
AB/SRAX:
Asymmetric bowtie with skewed radial axis index
AB/SS:
Asymmetric bowtie-superior steep
AB:
Asymmetric bowtie
ACA:
Anterior chamber angle
ACD:
Anterior chamber depth
ACV:
Anterior chamber volume
AD:
Ablation depth
B:
Butterfly
CCT:
Central corneal thickness
CR:
Cycloplegic refraction
D:
Diopter
DOF:
Depth of focus
FFKC:
Forme Fruste Keratoconus
Irr:
Irregular
IS:
Inferior steep
K-max:
Maximum K-reading
MA:
Manifest astigmatism
MR:
Manifest refraction
MRSE:
Manifest refraction spherical equivalent
O:
Oval
OZ:
Optical zone
PIOL:
Phakic intraocular lenses
PLK:
Pellucid-like Keratoconus
PMD:
Pellucid marginal degeneration
PMT:
Postmedriatic refraction
R:
Round
RS:
Reference surface
RSB:
Residual stromal bed
SB/SRAX:
Symmetric bowtie with skewed radial axis index
SB:
Symmetric bowtie
SF:
Smiling face
SS:
Superior steep
TA:
Topographic astigmatism
TL:
Thinnest location
V:
Vortex
VA:
Visual acuity