The brains behind the BAD
Simplifying pre-operative keratoconus screening
The early detection of ectatic change is of paramount importance to the refractive surgeon.Anterior curvature and ultrasonic pachymetry, alone,does not provide enough information to detect early corneal disease. The combination of anterior and posterior elevation and complete pachymetric data gives the clinician a more complete view of the
structure of the cornea and allows for more effective screening. The OCULUS Pentacam’s Scheimpflug Cross-sectional imaging (OCULUS Optikgerate GmbH, Wetzlar, Germany) provides for a three-dimensional reconstruction of the anterior segment, making possible the assessment of the anterior and posterior corneal surfaces and the creation of a complete pachymetric map. The Belin / Ambrósio Enhanced Ectasia Display (BAD display) was designed to utilise the data supplied by the Pentacam’s rotating Scheimpflug camera and provide a comprehensive keratoconus screening display. The display combines the anterior and posterior elevation and pachymetric data into one all-inclusive display giving the clinician a more complete overview of the corneal shape and allowing for quick and effective screening of refractive surgery patients.
The brains behind the BAD
Elevation Based Topography Book
Oculus proudly presents, the first published book of Pentacam: "Elevation Based Topography".
It was editored and authored by Prof. Michael Belin, MD, FACS and his fellow Stephen S. Khachikian, MD.
"The last thing I wanted to do is write a book", stated Michael Belin in his preface." Elevation based topography (or Tomography) is a new and comprehensive way of looking to the cornea, its structure, shape and performance. It is the authors belief, ..., that cross-sectional Scheimpflug analysis offers significant advantages in treatment, diagnosis and patients' safety". Further co-authors are Renato Ambrosio Jr., MD, PhD, Frederico Guerra, MD and Marcella Salomao, MD.
The main focus was given to screen patients for refractive surgery, the interpretation of elevation maps, corneal thickness maps and its progression analysis. Drs. Belin & Khachikian present the topic in an orderly, systematic method ,that starts with the basics and progresses to understanding complex cases. The book is extensively illustrated with generous use of color. This masterpiece should serve as a basic text for any refractive surgeon interested in understanding modern topography.
The Pentacam book "Elevation based Topography" was published from the Highlights of Ophthalmology, ISBN No.:978-9962-613-51-0.
It is available thru the local distributor of Pentacam in your country of residence.
Please check the distributor locator for more information.
Long-term stability of the posterior cornea after laser in situ keratomileusis
Forward protrusion or displacement of the posterior corneal surface is found topographically in eyes with ectasia after laser in situ keratomileusis (LASIK). Studies found that changes to the posterior corneal surface commonly occur after LASIK. The reported forward protrusion of the posterior corneal surface has characteristics similar to those of keratectasia and was believed to represent a subclinical form of post-LASIK ectasia.
Long-term stability of the posterior cornea after laser in situ keratomileusis [229 KB]
Evaluation of Anterior Segment Pathologies Using Pentacam
Pentacam Principle of Measurement
The Pentacam obtains images of the anterior segment by a rotating Scheimpflug camera measurement. The camera is a digital CCD camera with synchronous pixel sampling. The light source consists of UV-free blue LED’s with a wavelength of 475 nm. This rotating process supplies pictures in three dimensions and also allows the center of the cornea to be measured precisely. It also helps to avoid errors that may
arise from an omni-directional scan, influencing the entire 3D model. The software utilizes a ray tracing algorithm to construct and calculate the anterior segment.
Evaluation of Anterior Segment Pathologies Using Pentacam [686 KB]
Applications of PENTACAM in Anterior Segment Analysis
Pentacam-Scheimpflug in Corneal Diseases
Corneal transparency is a remarkable characteristic that is essential for vision. Biophysical models of corneal transparency have entirely focused on the stromal extracellular matrix and disruption of the regular array of collagen fibres as the main reason for corneal haziness. Therefore, disorder of corneal transparency has traditionally been explained by a combination of three main factors: (1) abnormal water content (i.e. swelling or oedema); (2) abnormal collagen fibre diameter, spacing, and orientation (i.e. scar tissue or fibrosis); and (3) abnormal accumulation
of macromolecules (proteins, glycosaminoglicans, lipids and others).
Applications of PENTACAM in Anterior Segment Analysis [1.9 MB]
Evaluation of Anterior Segment Changes
Following Laser Peripheral Iridotomy Using
Primary angle-closure glaucoma (PACG) is a major form of glaucoma in Asia.1 It is a leading cause of blindness worldwide. 2 Laser peripheral iridotomy (LPI) is the standard firstline intervention in both acute and chronic forms3. It is successful in preventing recurrence of acute attacks and virtually eliminates the risk of an acute attack in the fellow eye4. Peripheral iridotomy eliminates pupillary block, allowing the convex iris to flatten and widening the anterior chamber angle (Figure 1). Such changes in anterior chamber angle morphology are difficult to assess. Gonioscopy is difficult to perform in a reproducible fashion, limiting the ability to quantify changes after LPI.
Evaluation of Anterior Segment Changes [390 KB]
Using the Pentacam™ for IOL Power Calculation
Because of advances in surgical technique and IOL design, patients are more and more demanding of excellent uncorrected postoperative vision acuity. Achieving this goal requires a very complete preoperative evaluation, precise measurements, the use of appropriate IOL power calculation formulas, the selection of the most appropriate IOL for each individual patient, and a flawless surgical technique.
Using the Pentacam™ for IOL Power Calculation [1.0 MB]
The Pentacam Application for Intrastromal Segment Ring
The intrastromal corneal segment ring is a device designed initially to correct mild-to-moderate myopia by flattening the anterior corneal curvature without encroaching on the visual axis. The device is a two types PMMA transparent ring, one with an outer diameter of 8.1 mm and an inner diameter of 6.8 mm. It is precision lathe-cut to ±0.01 mm as a hexagonal-shaped section of a cone called INTACTS® and the other with 6.3 mm of outer diameter and 5.7 mm of inner diameter in a piramidal shape called FERRARA RINGS®. Those are inserted through a peripheral radial incision made with a diamond knife at two-thirds corneal depth into a 360° peripheral intrastromal channel created with specially designed instruments.1 Anterior corneal curvature is changed by using rings of different thickness. In order to offer the patient the most accurate correction in their ametropic defect we must evaluate corneal changes with advanced imaging modalities, many of which promise to deliver quantitative information and qualitative images of the cornea and anterior chamber. This equipments have a range of applications, including the diagnosis and tracking of pathology, the planning and monitoring of refractive surgery, and the study of accommodation.
The Pentacam Application for Intrastromal Segment Ring [1.3 MB]
New Advances and Technology with Pentacam
The early detection of ectatic disease is of paramount importance to the refractive surgeon. While measurements such as aberrometry and curvature can be used in evaluating a patient for ectatic disease, they are derivatives of elevation. With subclinical disease, anterior curvature alone may not provide enough information to detect an early corneal abnormality.
New Advances and Technology with Pentacam [1.8 MB]
Keratoconus / Ectasia Detection with the Oculus Pentacam:
Belin / Ambrósio Enhanced Ectasia Display
While the basis for the development of ectasia may ultimately be a structural, genetic, or biochemical abnormality of the cornea, measurable structural components, such as elevation and pachymetry should be thoroughly evaluated.1 The measurements must be reviewed in a comprehensive manner, rather than assessing isolated values. While measurements such as aberrometry and curvature can be used in evaluating a patient for ectatic disease, they are derivatives of elevation.2With subclinical disease, curvature alone may not provide enough information to detect early corneal abnormality.
Keratoconus / Ectasia Detection [1.5 MB]
The Pentacam: Offering a Clearer View
The Pentacam Comprehensive Eye Scanner (Oculus, Inc., Lynnwood, WA) continues to expand the field of ophthalmic diagnostics with new features and software, such as densitometry for cataracts. This and other key information on the Pentacam is presented in the following articles, which summarize presentations that were given at two breakfast symposia on November 10th and 11th in New Orleans.
The Pentacam: Offering a Clearer View [533 KB]
Elevate Yourself Above other O.D.s
Accurately measure corneal elevation and curvature in your patients.
Because corneal ectasia has become the common denominator for post-refractive surgery corneal transplants and the instigator for some of the largest lawsuits in refractive surgery today, we must properly screen refractive-surgery candidates for this and other corneal conditions that can preclude successful visual outcomes.
One way you can do this: by using the Pentacam corneal mapping device, from Oculus, Inc. The device provides elevation images of the anterior and posterior cornea.
The Pentacam difference
Common corneal topographers (placido disc imaging) are excellent devices, but you should not solely rely on these instruments to determine refractive-surgery candidacy, for two reasons:
They only measure the curvature of the anterior surface, which is only half of what determines candidacy. Many conditions, such as keratoconus, originally develop or provide clues from the posterior surface before we can see them on the anterior surface.
Imaging with these devices is based on one arbitrary reference point. Curvature, when imaged by any device, is an element of elevation of the cornea. The curvature is measured based off of a specific reference point. If this point is not exactly in the center of the map, the relative image of curvature is skewed.
PIOL Simulation for High Res Imaging
Ensuring postoperative safe distances between the iris-fixated phakic IOL and crucial tissues (eg, corneal endothelium, crystalline lens) remains one main challenge in phakic IOL implantation. To assure a more precise and accurate preoperative patient selection, we developed—in cooperation with Oculus Optikgeräte GmbH (Wetzlar, Germany)—a phakic IOL simulation software module. This module, applicable to the new high resolution Pentacam HR (Oculus Optikgeräte GmbH), will improve preoperative diagnostic evaluation. After entering the patient’s refraction, the software calculates the required refractive power of the phakic IOL that is stored in an integrated lens database. This individual phakic IOL is then projected into the patient’s anterior chamber, which has been obtained by regular Scheimpflug measurement. A three-dimensional calculation obtains the values of interest.
PIOL Simulation for High Res Imaging [90 KB]
Software simulates postop phakic IOL position
A study showed minimal differences between simulated and actual lens positions and indicates improved patient selection.
In an effort to improve the safety of phakic IOL positioning, researchers have developed imaging software that can preoperatively simulate the placement of the lenses. Testing showed good correlation between the simulated and actual position of the lens, according to one ophthalmologist. Mana Tehrani, MD, of Johannes Gutenberg-University in Mainz, Germany, said this software could help refractive surgeons identify patients who may be at risk of postoperative complications. “Long-term complications such as progressive endothelial cell loss, pigment dispersion or induction of cataract are still a concern,” Dr. Tehrani said. In cooperation with Oculus, the imaging device manufacturer, Dr. Tehrani and H. Burkhard Dick, MD, developed the software.
Software simulates postop phakic IOL position [131 KB]
PENTACAM System´s Overview: Understanding its Benefits
Theodo Scheimpflug (1865 - 1911) is the pioneer of aerial mapping. He invented the aerial photogrammetry using numerous technical instruments for land surveying from the air. Scheimpflug took photos of the landscape from a ballon or a kite. The resulting oblique views could not be used directly for creating a map but had to be deskewed at first. For this purpose, he createt a specific deskewing device which was completed in 1906. In 1907, he published his fundamental work "Die Herstellung von Karten und Plänen auf photographischem Wege" (The Making of Maps and Plans using Photography).
PENTACAM System´s Overview (español ) [578 KB]
PENTACAM System´s Overview (english) [578 KB]
Pentacam opens eyes to new diagnostic possibilities
Scheimpflug based anterior segment tomography
The innovative technology of the Oculus Pentacam HR is, with increasing clinical experience, fulfilling its promise as an essential tool for diagnosis, biometry and management of cataract and refractive surgery patients. Tobias Neuhann MD served as moderator of an EuroTimes Satellite Education Programme Symposium on the current state of Scheimpflug based anterior segment tomography during the XXIV Congress of the European Society of Cataract and Refractive Surgeons in London.
Pentacam - new diagnostic possibilities [654 KB]
The Pentacam: Precision, Confidence, Results, and Accurate “Ks!”
Many surgeons who use the Pentacam Comprehensive Eye Scanner (Oculus, Inc., Lynnwood, WA) for the first time worry about misinterpreting the images and mistakenly including or excluding refractive surgery candidates. The key to successfully screening patients with the Pentacam is to create a standardized template that always displays the same maps in the same order using consistent colors and scales. Once you become familiar with the system, you should be able to recognize patterns that tell you if the patient’s eyes are normal, usually in a matter of minutes, if not seconds.
Pentacam AAO 2006 [418 KB]
Aging simulation software for iris- fixated IOL position using high resolution Scheimpflug imaging
During the ESCRS Oculus launched the phakic IOL fitting simulation software for the Pentacam HR. This unique software tool allows an accurate pre-op simulation of the pIOL fit in the anterior chamber as well as the pre-op simulation of the pIOL position in up to 50 years after surgery.
Ms. Mana Tehrani MD, Johannes Gutenberg University in Mainz/Germany won the second price in the refractive category for her poster “Ageing simulation software for iris-fixated IOL position using high- resolution Scheimpflug imaging”. This price was sponsored from ALCON in the occasion of the ESCRS 2006 in London. Co-authors of this poster were J Koeppe and Prof. Burkhard Dick.
More information about the pIOL software:
Presentation - piol Poster ESCRS 2006 [PDF, high quality, 2909 KB]
Presentation - piol Poster ESCRS 2006 [PDF, low quality, 216 KB]
Pentacam News about the piol software
Comprehensive Diagnostic Imaging
OCULAR SURGERY NEWS
Refractive and cataract surgeons depend on precise diagnostic imaging to measure corneal architecture an power. Accurate measurement of corneal properties is key to developing successful screening parameters for refractive surgery and IOL implantation. The evaluating using Scheimpflug images from the cornea, anterior chamber and the lens is also crucial for refractive an cataract surgeons. Additionaly, the number of cataract patiens who have undergone refractive surgery has grown in recent years, presenting ophthalmologists with increased difficzlty in calculating the correct IOL power for lens implantation in a growing patient demographic. OCULAR SURGERY NEWS, through the support of Oculus, gathered an international group of refractive an cateract surgeons to discuss the use of diagnostic imaging technology. I would like to thank the faculty for sharing their throughts on the issues and Oculus for its support of the roundtable discussion held at the European Society of Cataract and Refractive Surgeons Winter Refractive Surgery Meeting in Monte Carlo.
Richard L. Lindstrom, MD
Chief Medical Editor
Comprehensive Diagnostic Imaging [1877 KB]
Placido-based corneal topography outdated, limited in scope
OSN SuperSite Breaking News 8/11/2006
BOSTON — Current placido-based corneal topography systems assume all corneas conform to a known conic section, not allowing for a more true shape representation, according to a surgeon speaking here.
In a keynote presentation at the American Society of Cataract and Refractive Surgery Summer Refractive Congress, Michael W. Belin, MD, discussed issues surrounding corneal topography. He said topographic analyses based only on placido-derived anterior curvature are incomplete; they show the corneal apex, line of sight and VK axis as the same.
He noted that in a study involving Bausch & Lomb’s Orbscan, the device incorrectly read the corneal thickness of one patient as being 37 µm thinner. It also showed an incorrect ectasia.
“It is like relying on an X-ray when a MRI is available,” Dr. Belin said.
In comparison, elevation data is independent of axis, orientation or positioning, according to Dr. Belin. He said all further maps of curvature can be derived from accurate elevation data.
“Keratoconus screening requires the use of topography systems that measure elevation data as their elemental requirement,” he said.
For further information: http://www.osnsupersite.com/view.asp?rID=18013
Scheimpflug Biometry of Anterior Segment After Implantation of Foldable Iris-fixated Lenses
The various surgical options currently availible for the correction of myopia, hyperopia, and astigmatism include corneal refractive surgery and lenticular intraocular procedures. However, phakic intraocular lenses (PIOLs) are becoming increasingly popular. In addition to preserving the corneal shape, PIOLs are potentially reversible...
This is an encrypted file sponsored from OCULUS from the publishing house which can be downloaded while following the instructions. For your information, you have to download a small .exe file to your computer. This is the usual process.
Scheimpflug Biometry of Anterior Segment [164 KB]
Why Cataract and Refractive Surgeons Need the Pentacam
Four surgeons discuss the device’s value, including new software additions.
Almost 10 years ago, I published an article1 showing the extreme variability between different topography systems in the analysis of abnormal corneal shapes. Since then, the ability to accurately image the anterior corneal surface has greatly improved. We are now being told, however, that the elevation of the posterior surface is important in diagnosing early keratoconus and post-LASIK ectasia. Currently, two commercially available systems are able to measure backsurface elevation: the Pentacam comprehensive eye scanner (Oculus, Inc., Lynnwood, WA), which is a rotating Scheimpflug device, and the Orbscan corneal topographer (Bausch & Lomb, Rochster, NY), a scanning slit device.
Why Cataract and Refractive Surgeons... [361 KB]
Topography and Scheimpflug Imaging
Pearls for refractive surgery screening and keratoconus detection.
BY MICHAEL W. BELIN, MD
Detecting keratoconus and performing topographic screenings prior to refractive surgery are particularly timely topics in light of Cataract & Refractive Surgery Today’s Anatomy of a Lawsuit II articles.1-4 After reviewing those pieces, it would be inappropriate for me to comment on the trial and/or its merit. What I will review is the confusing and often unresolved issue of what is topographic evidence of keratoconus.
I perform LASIK on the majority of my patients, but I have always performed a higher percentage (approximately 20%) of surface ablation procedures than is the norm for my geographic area. I have been involved with keratoconus and topography for the better part of my professional life and have presented more than 100 papers at national and international meetings...
Topography and Scheimpflug Imaging [112 KB]
A new look in the eye
Remember how you felt when seeing the first ultrasound photo of your child or grandchild? Your excited perusal of that fuzzy mass of light and dark? Even before the mother showed outward signs of pregnancy, the photograph showed so many details of the growing child.
Augenlicht Summer 05 [344 KB]
The Anterior Chamber, From Every Angle
A rotating Scheimpflug camera measures structure, topography, pachymetry and denistometry.
Christopher Kent - Senior Editor
As procedures become more complex and patient expectations increase, the need for more detailed and accurate clinical information about the eye continues to grow.
One of the new generation of instruments designed to meet that need is the Pentacam, from Oculus. Now approved in the United States for more than a year, the Pentacam provides both familiar and new measurements of the cornea and anterior chamber.
REVIEW Technology Update [583 KB]
The Optics of NearVision CK
The science behind the procedure’s effectiveness in treating presbyopia.
BY JACK T. HOLLADAY, MD, MSEE, FACS
Numerous investigators have found that NearVision CK (Refractec, Inc., Irvine, CA) provides very good near acuity with much less compromise in distance vision than one would expect from a monovision procedure. The reasons for this blended vision effect with NearVision CK, however, have not been well understood.
Clinical Review [129 KB]
EYE TO EYE
Interpretation of Scheimpflug Based Anterior Segment Imaging and Mapping
Ophthalmologists have numerous technologies at their disposal for imaging and investigating the cornea and anterior chamber. For years, conventional slitlamp,keratometry,ultrasound pachymetry,and Placido disc-based topography systems have served clinicians and researchers as helpful tools for evaluation and diagnosis.
EYE TO EYE Scheimpflug [394 KB]
AAO 2004 - A summary of all lectures
Next Generation Technology for the Cataract & Refractive Surgeon
This monograph is based on an educational seminar presented at the 2004 AAO meeting in New Orleans. In it, users of the new Pentacam Comprehensive Eye Scanner describe how the system allows them to perform a wide range of clinical services, from monitoring intraocular changes to treating a wider range of cataract and refractive patients than they could previously.
AAO OCULUS 2004 [331 KB]
Special Edition about the Pentacam
In a special edition the OPHTHALMO CHIRURGIE (www.kaden-verlag.de) is reporting about the Pentacam.
Five in One: An Innovation that combines several diagnostic strategies
Pentacam – The World’s First 3 D-Scheimpflug Camera.
For any ophthalmologist who
considers buying a new device
for his private surgery or clinic, the cost-benefit ratio of such an investment is of primary importance.
OPHTHALMO CHIRURGIE [549 KB]
Diagnostic Imaging for Refractive and Cataract Surgery
Advances in diagnostic imaging technology have brought the Pentacam system (Oculus, Inc., Lynnwood, Wash.) to the forefront of the cataract and refractive surgery market. Other instruments and methods traditionally used to obtain diagnostic information do not possess the Pentacam’s precision.
Diagnostic Imaging [405 KB]