Adoption Strategies and Patient Selection With Topography-Guided LASIK

Detailed knowledge of the technology is key.

By Charles R. Moore, MD, and Bennet Chotiner, MD

One of the most important things to remember when discussing the topography-guided LASIK custom treatment procedure on the WaveLight Excimer Systems (Alcon) is that there is no such thing as a “normal” topography-guided refractive surgery procedure.

In my experience, delivering successful topography-guided LASIK custom treatments requires a detailed knowledge of the technology, the physicians’ personal involvement in the patient’s evaluation and treatment from start to finish, and the acquisition of pristine topographic images.

Knowledge of Topography

Because topography-guided LASIK custom treatments are created from the patient’s own topographic data, surgeons must have a solid understanding of how to capture high-quality images with the WaveLight Topolyzer Vario (Alcon). Then, they must know what to look for on those topographic images in order to build a customized treatment plan for the patient. Furthermore, the device includes software for conducting pupilometry, something that many topography units lack and with which surgeons may need to familiarize themselves.

Involvement In Evaluation And Treatment From Start To Finish

Topography-guided LASIK custom treatments require the surgeon to personally plan and execute the treatment, because its successful execution depends on the accuracy of the topographic examination and image capture. The WaveLight Topolyzer Vario must be able to capture at least 70% of the corneal surface and 100% of the imaged pupil in order for the surgeon to successfully execute the procedure. Therefore, when capturing the patient’s initial topographic image, surgeons must be careful to guard against centering errors, inadequate coverage, issues with pupil tracking or mires recognition, and shadows from the eyelashes or nose that will degrade the quality of the map. Because this information is gathered in analog form, it must be accurate before it is digitized, compressed, and transferred onto the computer.

Acquisition of High-Quality Topographic Images

Because of the high-quality topography maps necessary to perform topography-guided LASIK custom treatments, surgeons may have to take a few extra steps that are not necessary with standard topographical screening tests. He or she may have to place a speculum or tape the eyelids away from the visual field. In some cases, long eyelashes may need to be trimmed. The patient must be looking directly at the fixation target to capture a good Topolyzer Vario map, although the surgeon may need to decenter the head position so that the nose is farther away. It is also important that the mires are clear and well defined.

The goal is to capture a reproducible topographical image of the corneal irregularity. In the US Food and Drug Administration’s clinical trial of the topography-guided LASIK custom treatments, we investigators used four acceptable topographic pictures. We ensured that the pupil accurately identified and tracked 360º. We also checked to make sure the mires were as crisp and clear as possible.

Even with the best methodology, however, screening failures can occur. There are some patients for whom the surgeon may not be able to acquire adequate diagnostic information to qualify the patient for the topography-guided LASIK custom treatments. Individuals with irregular corneas, small optical zones, ectasia, or early keratoconus need to be informed that they may need more than one topography-guided LASIK custom treatment. Preoperative education is necessary so that patients understand the process of trying to restore visual function to an abnormal cornea and do not expect same-day results like normal LASIK recipients enjoy.

Acquiring Topographic Information

By Ronald Krueger, MD

Patients must stop wearing contact lenses before their screening examination, and they should not wear them again before the LASIK surgery. Wearing contact lenses can change the shape of the cornea and affect the surgery’s outcome. The length of time to remove contact lenses before the screening examination depends on the type of lenses the patient is wearing (Table).

Patients who currently wear contact lenses or have worn them in the past few months will be required to complete one or more additional screening visits to assess their eyes’ stability for surgery. Unstable eyes are not good candidates for topography-guided LASIK custom treatments. As part of the screening tests, physicians should capture the following:

• Visual acuity
• Manifest refraction and cycloplegic refraction
• Topography, keratometry, aberrometry, pachymetry
• Intraocular pressure
• Slit-lamp examination
• Pupil size
• Dilated funduscopic examination
• Contrast sensitivity and low-contrast acuity

Surgeons should obtain a minimum of four topography images for each eye with the Allegretto Topolyzer (Alcon), which will be used to create a treatment plan. In addition to the tests and measurements discussed above, others may be required based on the patient’s anatomy.

Ronald Krueger, MD, is the medical director of the Department of Refractive Surgery at the Cole Eye Institute of the Cleveland Clinic Foundation in Cleveland, Ohio. He may be reached at (216) 444-8158; krueger@ccf.org. Dr. Krueger is a paid consultant for Alcon.

The Decision to Treat

Once the surgeon is able to capture reliable, high-quality topographic images, the he or she can determine a treatment plan and decide whether there is adequate tissue to perform LASIK versus PRK. This, too, is a surgical decision that requires the surgeon’s active involvement. Surgeons who cannot commit their time to topography-guided LASIK custom treatments may not be the best candidates for using this technology.

Bennet Chotiner, MD

CASE STUDIES

Case 1

Figure 1. Case 1: Right and left eyes preoperatively; November 2009.

Figure 2. Case 1: Right and left eyes postoperatively; October 2010.

In 2009, our office manager (37-year-old woman) asked to undergo a topography-guided LASIK custom treatment because she was impressed by the outcomes she was seeing in our study patients. Preoperatively, she had -5.50 D of sphere in the right eye with a BCVA of 20/20 with spectacles, and 20/20 UCVA in the left eye (Figure 1). After my staff and I performed the topography-guided LASIK custom treatment in the patient’s right eye, its refraction was -0.25 +0.25 × 180, which gave her a UCVA of 20/20 +2 (Figure 2). The left eye after treatment was -0.25 +0.25 × 015, for a final acuity of 20/20 +1. She prefers the vision in the right eye, which received the topography-guided LASIK custom treatment.

Case 2

Figure 3. Case 2: Right and left eyes preoperatively; January 2010.

Figure 4. Case 2: Right and left eyes postoperatively; January 2011.

A 31-year-old high astigmat presented with a preoperative refraction of -8.75 0.25 × 135, BCVA of 20/20 in the left eye, and -9.00 +0.50 × 060 in the right eye, giving her a BCVA of 20/20 (Figure 3). The right eye received the topography-guided LASIK custom treatment. Postoperatively, her UCVA was 20/15+ in the right eye and 20/16 in the left (Figure 4). n

1. Summary of Safety and E ectiveness Data. P020050S012d

Charles R. Moore, MD
• Clinical investigator for topography-guided LASIK custom treatments
• (713) 984-9777; crm@texaslasik.com
• Financial disclosure: consultant to Alcon

Bennet Chotiner, MD
• Founder and medical director of the Memorial Eye Institute in Harrisburg, Pennsylvania.
• Clinical investigator for topography-guided LASIK custom treatments
• (713) 984-9777; crm@texaslasik.com