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If there is one thing I wish my current self could tell my younger self, it is that the more information you have, the easier it is to provide the very best service to your patients. In my 33 years of private optometry practice (as owner of Today’s Vision Sugar Land), I have learned that the difference between a successful and unsuccessful outcome—whether while performing surgery, monitoring disease progression, or fitting a sophisticated contact lens—is information. Information is critical in so many aspects of our practices, but none so much as in diagnostics.
For me, the Pentacam (Oculus) is an indispensable diagnostic tool that provides the basis for precise and reliable diagnostics and successful treatment of the anterior segment. The reason the Pentacam technology is the gold standard worldwide1 is because it does its job well and does not overwhelm with information not useful in planning patient care. We have only had the Pentacam a short time, but I am already wondering how we worked without it. Its interface is incredibly intuitive, resulting in a short learning curve for our staff.
How the Pentacam Technology Works
We use the Pentacam mainly for early ectasia detection and glaucoma, refractive, and preoperative and postoperative screening, as well as for cataract and refractive surgery planning.
The Pentacam combines a slit illumination system and a Scheimpflug camera, which rotate together around the eye. A thin layer within the eye is illuminated through the slit, and the cells scatter the slit’s light. This creates a sectional image that is then photographed in a side view by the Scheimpflug camera. Both the anterior and posterior surfaces are measured from limbus to limbus, and corneal thickness is represented over the whole surface. This allows us to quickly determine the thinnest part of the cornea (to pre-emptively screen for keratoconus), but also gives us a quick and reliable overview of the entire cornea.
We have found the image is not affected by the patients’ tear film. Because a large number of patients have dry eyes, we need to be cognizant of how their surface issues may affect imaging. For patients who use artificial tears, we can compensate for potentially false data. Fortunately, the Pentacam is designed to overcome that issue, ensuring an accurate image.
All sectional images are saved and corrected in relation to a common reference point. The images are then combined to create a 3D model of the entire anterior eye chamber, which lets us look at the surface of the cornea rather than a reflective image. This is a huge benefit as it makes it possible to generate reproducible tomographic images of the anterior eye in any desired plane.
Early-Stage Keratoconus Detection With the Pentacam
To me, the Pentacam represents the gold standard in corneal topography and tomography, and I believe it will for years to come. In 5 years’ time, I believe Placido disc technology will fall by the wayside because of the superiority of Pentacam’s direct imaging system. The Belin/Ambrósio Enhanced Ectasia Display2,3 helps recognize keratoconus at an early stage (Figure 1). Keratoconus can be difficult to diagnose, and early forms normally go unnoticed unless a corneal tomography is performed. Corneal thinning frequently precedes ectasia, and visual acuity loss is poorly corrected with spectacles or contact lenses—eventually these corneas become contact lens intolerant. In our practice, we see several keratoconus patients weekly and most need to be fit with scleral lenses and/or need their postoperative recovery managed. Imaging has become an invaluable means to do this with extreme proficiency.
The Pentacam can distinguish changes in the back surface of the cornea, which is where the earliest changes in keratoconus occur. The Belin/Ambrósio display2,3 has become my go-to for early detection of keratoconus. The display allows us to provide our patients with a definitive answer about whether or not their keratoconus is stable or progressing. It is a game changer.
The Pentacam has also become our preferred tool for detecting vertex normal (clinically considered to be the visual axis). A patient with keratoconus may have a markedly displaced corneal apex inferiorly, which makes fitting lenses difficult. Aligning the visual system with the apex of the cornea and the line of sight is critical when fitting lenses in these patients (Figure 2). The Pentacam details the X and Y coordinates, removing the guesswork for our staff.
Effective Glaucoma Screening
Glaucoma is a leading cause of preventable blindness in the United States, and its incidence is only expected to increase as the population ages.4 Symptoms are often lacking during early stages, and visual acuity loss is permanent. The Pentacam evaluates the iridocorneal angle and chamber volume based on normative data and clinical pictures, thus giving you a more precise evaluation of patients with suspected glaucoma (Figure 3).
Scheimpflug imaging, elevation data, 3D analysis, topography, and pachymetry are all done at once and combined to give you a thorough, comprehensive picture. The ability to get global pachymetry without special testing is amazing. This helps alleviate both physician and patient burden by limiting the amount of time patients have to undergo screening and testing.
Intuitive Interface, Quality Tech Support
One of the best features of the Pentacam is its intuitive interface, which allows our practice to organize preoperative planning with ease. The equipment is straightforward, the software integration is fantastic, and, as I alluded to earlier, there is virtually no learning curve.
The Pentacam can be easily networked between workstations and between locations. This is a huge benefit for larger practices with several offices. We integrated the Pentacam into our network quickly and easily, allowing us to synchronize examination data, optimize work processes, and save time and money.
A Worthy Investment
The Pentacam is certainly an investment, and it is the most worthy kind: an investment in better patient care. It is contact-free, hygienic, and painless. The measurement, which takes about 2 seconds, is not invasive or glaring, maximizing patient cooperation. There are numerous procedures that can be reimbursed for Pentacam use5 and the system will readily pay for itself. The footprint of the unit and the computer are very small, making it easy to incorporate even when space is at a premium. The Pentacam has changed the way I practice and enhanced the quality of my patient care.
1. Data on file, Oculus. Available at: https://www.pentacam.com/us/start.html.
2. Ambrosio, R Jr. Simplifying ectasia screening with Pentacam corneal tomography. Highl Ophthalmol. 2010;38(3):12-20.
3. Belin MW, Ambrosio R Jr. Scheimpflug imaging for keratoconus and ectatic disease. Indian J Ophthalmol. 2013;61(8):401-406.
4. Glaucoma Research Foundation. Glaucoma Facts and Stats. http://www.glaucoma.org/glaucoma/glaucoma-facts-and-stats.php. Last reviewed November 16, 2016. Accessed May 4, 2017.
5. Corcoran Consulting Group. Reimbursement for tests with the Oculus Pentacam. https://www.corcoranccg.com/products/faqs/oculus-pentacam/. Last updated April 26, 2016. Accessed May 4, 2017.
Thomas P. Arnold, OD, FSLS
• private practice at Today’s Vision in Sugar Land, Texas
• financial disclosure: speaker for AccuLens: EyePrint Prosthetics, Bausch & Lomb Specialty Vision Products, Blanchard Lab, Oculus, and Physician Recommended Nutriceuticals