Smartphones Take on Astigmatism

Surgeons say you can make use of a powerful tool you almost always have with you to help tame patients’ cylinder.

Walter Bethke, Managing Editor
6/5/2014

A maxim among photographers states that “The best camera is the one you have with you,” implying that no amount of expensive equipment is going to help you if it’s sitting back at your house. Along those lines, ophthalmologists are discovering that the device most of them always have with them—their smartphone—may be useful for any number of tasks in and out of the clinic. One of these tasks is dealing with astigmatism, in terms of marking a toric intraocular lens patient’s axis as well as calculating the surgically induced astigmatism. In this article, we’ll look at three devices and apps, developed by surgeons, that harness the power of smartphones to help wrangle astigmatism.

Astig PLOT

Astig PLOT is an app created by Edmondo Borasio, MD, head of cornea and refractive surgery at Moorfield’s Eye Hospital in Dubai, United Arab Emirates, as a handheld method for surgeons to analyze astigmatism in a group of eyes. The application plots preop/postop astigmatism, aggregate astigmatism, surgically induced astigmatism and mean astigmatism. The program also supplies the standard deviation of the mean astigmatism and the surgeon’s SIA.

To use Astig PLOT, the surgeon enters the input values into a comma-separated value file that he uploads to the application. “The surgeon enters pre- and postoperative K values, or refractions, and their respective meridians, or axes, and the program will calculate the mean arithmetic and mean vector SIA,” explains Dr. Borasio. “The program shows the SIA in terms of sphere magnitude, cylinder magnitude and meridian/axis, and also shows the conversion of the SIA to Cartesian (x,y) notation. Cartesian notation is needed when calculating the mean of multiple individual SIAs.”

Dr. Borasio says he developed the application after running into annoying impediments with statistical analysis programs. “I was fed up with using standard statistical analysis programs in which I had to format the graph, change the scale and reformat the axes each time I used them,” he explains. “The Astig PLOT graphs are autoscaling to the highest value in the series, but also allow you to choose a custom scale if, for example, you wish to compare two graphs from two different series. In such a case, you would choose the same value for both graphs.
A New Online Algorithm to Help Diagnose Uveitis
Figure 1. The Diagnose Uveitis application helps with differential diagnoses.
The etiology of uveitis can be tricky to elucidate. It may involve a large differential diagnosis and require multiple lab tests. Ophthalmologists at the Medical University of South Carolina Storm Eye Institute have developed a simple algorithm to assist comprehensive ophthalmologists in the differential diagnosis and testing for uveitic patients. The algorithm goes through a series of simple questions about the particular patient and then delivers a likely differential and recommended testing. Disease entities are then linked into the American Academy of Ophthalmology EyeWiki website to provide more quality information quickly. It provides a great starting point for ophthalmologists to provide excellent care to the patient.

The algorithm has been developed into an online and mobile application, which is available free to all ophthalmologists. It is formatted for full web browsers, iPhone and Android operating systems. The developers hope the application helps ophthalmologists to hone both their differential diagnoses and the testing ordered.

The team that developed the algorithm includes George Magrath, MD, MBA, Andrew Reynolds, MD, Reid Turner, MD, and Lynn Poole Perry, MD, PhD. They invite all ophthalmologists to give the application a try and give them your feedback, as they are continually working to improve the application. Their goal is to provide a practical and useful tool to assist comprehensive ophthalmologists with the care of uveitic patients. The application is available at diagnoseuveitis.com. Contact Dr. Magrath at magrath@musc.edu.
 
There is also an option to plot on the same graph the individual patient results of two different series, which is useful for making a visual comparison. For example, the two series could be pre- and postoperative astigmatism values of the same series or they could be the postoperative astigmatism from two different series in order to determine which of two techniques induced less astigmatism and achieved more consistent results.”

Astig PLOT is available for iOS 4.3 or later on the Apple App Store, and costs $19.99. For information, visit edmondoborasio.com.

Steinert/Oliver Marker

The Steinert/Oliver Smart Phone Marker from Rhein Medical is the brainchild of Stanford University’s Roger Steinert, MD, and Alejandro Oliver, MD, of Timmins and District Hospital in Timmins, Ontario, Canada. Rather than a software application, it’s the fusion of an instrument and a smartphone. “We’d been looking to use smartphones as levels for toric lenses and toyed with several adapters for the different phone brands,” explains Dr. Oliver, “There are so many phones out there, however, that it made it challenging to find one adapter that worked for all of them. So, we got the idea that we can hook the instrument to the earphone jack because, no matter what brand of smartphone you have or which generation it is, it has an earphone jack, and the earphone jacks are exactly the same across the board.”

To use the marker, the surgeon downloads one of many level apps available and plugs the marker into the earphone jack. The level app will indicate when the marker is being held exactly horizontally level, allowing the surgeon to mark the patient’s eye before surgery. “My preference is to mark the zero to 180 axis,” says Dr. Oliver, “So, I basically mark at 3 o’clock and 9 o’clock. I mark this axis bedside after the patient’s been through all the paperwork and before he’s gotten any dilating drops. Then, in the operating room, I use a Mendez ring and a marker to mark the meridian of the astigmatism. You’ll get a very durable mark, but you have to make sure the patient doesn’t rub his eye after you’ve made it. This is especially true if there’s lidocaine gel on the ocular surface. Alternately, you could also use the smartphone to mark the desired IOL axis in one step. To do that, however, you sometimes have to hold your hand in certain awkward positions. But, if you’re OK with holding your hand like that, you can do the mark once and that’s it; you won’t have to bother making additional marks in the OR.”

The kind of level application the surgeon uses can have an effect on the ease of use, and possibly the accuracy, of marks made with the instrument. “There are a lot of level apps out there for smartphones,” says Dr. Oliver. “My preference is not the bubble-level app, but instead a level app with an actual dial. The bubble app is a little too qualitative for me—you can be off by a few degrees and not be able to really tell. Therefore, a level app that has actual continuous gradations in degrees is ideal, since you get a quantity.”

The Astig PLOT app can graph patients’ pre- and postop astigmatism and calculate your surgically induced astigmatism. ( Image courtesy Edmondo Borasio, MD.)
As with any kind of measurement, the axis marking process is only as good as the accuracy of the smartphone level application that you use in conjunction with the marker, so Dr. Oliver says it’s important to make sure that when the smartphone says it’s horizontal it actually is in that orientation. “There have been reports about errors with the accelerometers of certain devices that will lead to incorrect measurements,” says Dr. Oliver. “Each level app you download has a calibration mode you can use. You want to make sure the level makes sense, so either use the device’s calibration function or just take a level you have at home and make sure when the phone reads itself as horizontal it actually is.”

The marker costs $295. For information, visit rheinmedical.com or call 1 (800) 637-4346.

Toreasy

Paris ophthalmologist Damien Gatinel says he developed the non-contact Toreasy astigmatic axis application to try to overcome sources of error that can crop up when patients move or tilt their heads. “When you mark the eye with a pendulum marker, you are trying to align the axis of the marking system with a horizontal orientation as perfectly as you can, so you’ll at least know where the zero/180 axis is,” he says. “But this relies on your marking skills, and the patient will sometimes rotate his head to try to make you more comfortable with your manual marking. But this rotation, unfortunately, introduces more error.”

To try to eliminate having to touch the patient to acquire the axis, Toreasy takes advantage of smartphones’ built-in accelerometers and gravity sensors. “Toreasy will constantly track the zero/180 direction on the screen using a bar that is unaffected by any rotation or tilt that you introduce by holding it. It will always give a level line. So, looking through the phone’s display, you face the patient and ask him to slightly tilt his head until the zero/180 line goes through both pupils. This is the proper head orientation. You then ask the patient to stay still and you zoom in on one eye and take a snapshot. You then examine the picture you’ve taken and find a vessel or other mark on the eye and use an on-screen reticle to mark its position. The app will mark it on the screen and give you the landmark’s position in degrees. If there are no vessels or prominent ocular structures that you can easily find, you can use a pen to place a mark on the eye wherever you want before you capture the image and place the reticle on that. Either way, you’ll know exactly where that mark is in relation to the zero/180 axis in degrees.

The Steinert-Oliver Smart Phone marker fits into the earphone jack of a phone and uses a digital level to help mark the eye. ( Image courtesy Alejandro Oliver, MD.)
“Then, at the time of surgery, you use a Mendez ring and the smartphone’s images to mark the intended axis of the IOL,” Dr. Gatinel continues. “You can do this because once you know that the blood vessel landmark is a certain number of degrees away from the horizontal line or the IOL axis, it’s easy to move from that location to the proper IOL axis and mark it.” To avoid obscuring important ocular landmarks, the degree ring on the Toreasy display is slightly transparent.

Dr. Gatinel says that, after having used the Toreasy marking system for a while, he’s learned that the farther away the anatomic landmark is from the center of the image, the more precise the degree mark will be. “If you pull the reticle arrow using your finger farther out into the periphery and then select the degree location, you’ll get extra precision,” he says. “You can make more precise, fine adjustments.”

In terms of centering the Toreasy gauge on the image of the eye, Dr. Gatinel recommends using the patient’s limbus rather than the center of the pupil. “We recommend using the limbus because the IOL won’t be centered if you center the axis measurement on an eccentric pupil,” he says. “The intraocular lens centers in the capsular bag, which is probably more aligned with the limbus than with the pupil, the latter of which tends to sometimes move in a non-concentric way.”

The Toreasy app for astigmatic axis marking uses smartphones’ built-in accelerometers and gravity sensors to give a perfectly level horizontal line for use in marking the zero/180-degree axis without having to physically touch the patient’s eye. ( Image courtesy Damien Gatinel, MD. )
 
Once the surgeon captures the eye image with Toreasy, he can then use the application’s reticle to mark the location of a prominent ocular landmark. Knowing the meridian of the landmark lets him find the toric lens axis later in the operating room. ( Image courtesy Damien Gatinel, MD. )

Toreasy is available for Android-based devices at the Google Store for $200 ( https://play.google.com/store). It’s also available pre-loaded on a new Samsung S4 Zoom smartphone for $2,500. Dr. Gatinel says it will work on Apple iOS devices but isn’t yet available on the Apple App Store.

Since a lot of the accuracy of the digital marking process with Toreasy relies on the smartphone’s camera, Dr. Gatinel recommends using the application on a device with a high-resolution camera, such as the latest generation of Samsung devices (S4, S4 Zoom and S5, for example). He says a good zoom feature that maintains a sharp image is helpful also, since it makes it easier to locate ocular features. For more information on Toreasy, visit toreasy.com REVIEW


All of the surgeons interviewed have a financial interest in their respective apps or devices.