As patients demand better refractive results following cataract surgery, new technologies are available to help you better deliver those outcomes. While astigmatism correction usually comes down to an educated guess, intraoperative aberrometry and image-guided systems help ensure that toric IOLs and limbal-relaxing incisions (LRI) are placed in a way to get patients as close to perfect vision as possible.
Intraoperative aberrometry's time
Intraoperative aberrometry is one of the latest advances designed to help surgeons achieve better astigmatism outcomes. Typically, a cataract surgeon determines the astigmatism treatment plan pre-operatively based on the patient's biometry measurements, and doesn't find out if the astigmatism is reduced sufficiently until the patient recovers. Enter aberrometry, which uses a device attached to your microscope to analyze a patient's refractive power in real-time as you operate.
Aberrometry works by bouncing a light off of the patient's retina and analyzing the wavefront that comes back, telling the surgeon if the astigmatism has been reduced. The technology lets a surgeon know if he's hit the mark, or if he needs to rotate the toric IOL or change the LRI to achieve better refractive power. It also can guide a surgeon in choosing the correct power of the toric IOL. This helps to limit the number of patients who end up with less-than-optimal results and need another procedure or LASIK after recovery.
Both aberrometry systems on the market offer similar information in different formats. One aberrometer depicts refractive power measurements through something that looks like real-time video, while the other essentially lets you take "snapshots" during the procedure. The devices attach to your microscope and are generally about 3 inches deep and a foot long, which add some size and takes some getting used to. Keep in mind that these systems are merely designed to help verify a physician's treatment plan while in surgery, not replace those essential pre-operative calculations and measurements.
Intraoperative aberrometry is especially useful in 2 situations during toric IOL alignment and in cases with post-refractive or LASIK patients. With toric IOL alignment, you don't always know exactly where the lens is sitting and if it's giving your patient the correct refractive power. After initially aligning the lens, you can use the aberrometer to ensure that it's at the correct axis, improving your patient's vision. In post-refractive or LASIK patients, there can often be a "refractive surprise," where the post-op outcome is less than desired since it's often harder to determine the corneal power of these patients pre-operatively. By enabling you to check and refine your treatment plan during the procedure, it reduces refractive surprise, leaving patients happier and limiting the number of post-op corrections you must perform.
Role of image-guided systems
While intraoperative aberrometry is a great way to check your progress, image-guided systems are designed to create a smooth process of planning and executing refractive cataract surgery. This new technology incorporates several digital planning and surgical positioning tools aimed to avoid errors that can occur between the initial patient evaluation and the day of the procedure.
Image-guided systems work by first using a diagnostic machine to take a pre-op "photo" of your patient's eye that shows the shape and measurements of the cornea, locations of limbal vessels and other important readings. Those measurements are then held in the system's software and are used to help you determine where to place the lens or incisions. After your pre-op planning is complete, the software takes your planned incisions and/or lens placement and sends it to a device attached to your microscope that creates an overlay to guide you during surgery.
Some of these systems also include software to help calculate the power of the IOL you need to use to correct the astigmatism. As with the aberrometer, this doesn't alleviate the need of the surgeon to make his own manual calculations, but can certainly help aid or confirm his decisions. The real star of these systems is their ability to produce the overlay used on the day of surgery. The overlay helps you pinpoint exactly where the axis of the lens must be or where you should make your LRIs, increasing your accuracy and your patients' refractive outcomes.
As an added bonus, image-guided systems also typically perform basic measurements you need to take before surgery, like topography and pupil size, which not only makes them very intuitive to use but can increase efficiency. Plus, at least 1 system is compatible with other manufacturer's microscopes, which may help to keep costs down when purchasing this technology.
When correcting astigmatism during cataract surgery, the outcome is largely determined by whether the surgeon correctly marked the 90-degree meridian on the patient, and if the readings and information taken during the first pre-operative evaluation remain constant and correct throughout the surgical process. Basically, there's a lot of room for human error. Since image-guided technology is a closed system, the measurements and data are directly transferred from the diagnostic machine to the surgical positioning tool used to guide the surgeon during the procedure, virtually eliminating recording errors between the initial visit and the day of surgery. Plus, several manufacturers' systems work with related equipment like phaco machines or femtosecond lasers, so the data is smoothly transitioned from one piece of equipment to the next. This is a huge benefit and can help eliminate mistakes on several levels including charting a wrong measurement or incorrectly marking the cornea on the day of surgery.
With the goal of a seamless transition from pre-op to post-op, some image-guided systems complete the cycle by also allowing you to enter the patient's post-op refractive power. The software then compares those results to the initial astigmatism treatment plan, and uses an algorithm to account for any differences in expected and actual outcomes, optimizing your results over time. Many centers, including my own, already have a similar system in place, but it involves several manual entries into different computer programs and is much more tedious than these all-in-one systems.
SEMANTICS OF STERILIZATION
When CMS banned the routine use of immediate-use steam sterilization (flashing) last August (tinyurl.com/oodxc49), many ophthalmic surgical centers feared that they'd have to buy new sterilization units and many more sets of instruments. Apparently it was all a mixup between immediate-use (IUSS) and short-cycle sterilization. CMS told several ophthalmic societies over several meetings that the vast majority of ophthalmic ASCs use short-cycle steam sterilization, not IUSS, which is fine as long as you adhere to the sterilizer manufacturer's directions for use (DFUs). In short-cycle steam sterilization, there's a dry time, and instruments are packaged in a wrap or rigid sterilization container, and stored for later use. Last month CMS issued the following clarification (not a policy change) to Outpatient Surgery Magazine:
In recent conversations with representatives of various ophthalmic surgery groups, CMS noticed that there continued to be some confusion between IUSS and other very short-cycle sterilization techniques. In particular, it appears that some in the eye surgery industry routinely use the term "immediate use steam sterilization (IUSS)" instead of "short-cycle sterilization" to describe their instrument sterilization process. Short-cycle sterilization is a form of terminal sterilization, and eye surgery centers participating in Medicare as either ambulatory surgical centers or hospital outpatient surgery departments, using short-cycle sterilization and following all manufacturers' instructions for use would comply with Medicare requirements governing sterilization.
Prices and purchasing decisions
When you have patients paying an additional $2,000 to $5,000 for improved vision, you need to deliver. Aberrometry and image-guided technology are 2 ways to do that. Combined, these systems can create a nearly perfect cataract suite, letting you plan for surgery, have a guide available while you're operating and check your patient's outcomes intraoperatively. But, I've found that most facilities are currently purchasing 1 or the other, depending on their case mix, budget and surgeon's preference.
Compared to other equipment, like femtosecond lasers, these new technologies can be a more cost-effective way to increase your accuracy and outcomes. Aberrometry systems cost $55,000 to $100,000. While the newer image-guided systems may cost slightly more, their costs vary widely and really depend on the manufacturer. Both technologies can also come with a click-fee or monthly fee that is usually passed on to the patient, and some may be leased depending on the vendor. You'll also want to consider the size of your facility if you have 2 ORs, are you buying 2 machines? Or will you just have 1 OR where all premium cases are performed? Again, the answer changes on a facility-by-facility basis.
Also consider surgeon preference. While these new technologies are extremely helpful for young surgeons or those who are new to refractive cataract surgery, veteran docs may only see a slight benefit. Still, as more and more patients demand improved vision post-op and are willing to dig into their pockets for premium services having this technology helps ensure you can deliver those outcomes they expect.
SMARTPHONES + ASTIGMATISM
If expensive corneal marking tools like intraoperative aberrometry or image-guided systems aren't in your budget, consider a free iPhone app called Axis Assistant that marks the axis of implantation of a toric intraocular lens or any corneal procedure where it's necessary to determine the axis. You place the patient's necessary biometry readings into the app, which then helps you determine the axis of the toric IOL. Then you take your iPhone and sit it in front of the slit lamp and align the slit with the axis shown on the iPhone. You can then mark the cornea using your preferred method. It uses the rotating slit of a slit lamp to match the desired axis while looking through the biomicroscope. The app is also useful for measuring the post-operative axis to assess whether there's any difference between the planned meridian vs. the achieved meridian. There's also an arc feature to use on situations where an arc is necessary, such as in intracorneal segments, corneal arcuate incisions and limbal-relaxing incisions.
Download the free Axis Assistant at tinyurl.com/qjgvzzm.