The use of smartphones has exploded in the past decade, as has the number of available phone applications (apps). Today, surgeons continue to find fascinating ways to use our smartphones—both outside and inside of our practices. The App Store (Apple), for instance, has an entire section labeled Apps for Doctors.
AT A GLANCE
• The Toreasy and Toraxis apps are noncontact solutions for marking the orientation of the eye and its anatomic elements.
• A high-definition snapshot of the eye allows the user to zoom in so that any element in the picture can be easily located and its exact angle coordinates determined in order to establish a reliable orientation mark for toric IOL alignment.
Recently, the Toreasy (Android/Google Play) and Toraxis (iOS/App Store) apps became available as noncontact solutions for marking the orientation of the eye and its anatomic elements. The primary goal of these apps is to help the surgeon align toric IOLs during cataract surgery.
HOW IT WORKS
Most modern smartphones are equipped with gyroscope and accelerometer sensors (remember the air bubble level app on the first iPhone?) in order to track the position of the smartphone and to provide its user with permanent, stable, and reliable orientation in space. As gravity is the only force that permanently points down toward the center of our planet, parallel to the 90° axis meridian, it provides a ubiquitous way to reference any direction. Hence, this makes it easy for the device to display an artificial horizon line superimposed on the camera view screen, even if the smartphone is not held in perfect horizontal or vertical orientation. It can also display a circular reticule, graduated over 360°, to allow location of any pinpoint on the screen with an angular precision of less than 1° (Figure 1).
Figure 1. Basic features of the Toreasy and Toraxis apps. The blue reticule is graduated over 360°. The patient’s name and the type and desired axis of the toric IOL are entered in the welcome screen.
When using the Toreasy or Toraxis app for toric IOL alignment, the head of the patient is positioned so that a virtual horizontal line crosses the pupils of the right and left eyes. Then a snapshot of the eye is taken. Augmented reality azimuth marks, which are continuously realigned using the gyroscope sensors, are then displayed on the visualization screen. The high-definition snapshot of the eye allows the user to zoom in, so that any element in the picture—blood vessel, pigmentation mark, etc—can be easily located and its exact angle coordinates determined in order to establish a reliable orientation mark.
Once the patient is prepped and draped, the desired toric IOL axis orientation can be referenced on the patient’s eye during surgery using a Mendez ring or projection technology built into the surgical microscope.
CONCLUSION
Toric IOL implantation requires the surgeon to locate and create reliable orientation marks. A process that used to be cumbersome, involving axis markers and bubble levels, is now considerably easier thanks to modern technology. The Toreasy and Toraxis apps are the first smartphone-enabled, noncontact solutions for eye axis marking. A brief description of the principal steps in their use is outlined in the graphic below.
Damien Gatinel, MD
• Assistant Professor and Head, Anterior Segment and Refractive Surgery Department, Rothschild Ophthalmology Foundation, Paris
• Director, CEROC, Paris
• Member, CRST Europe Editorial Board
• gatinel@gmail.com
• Financial disclosure: Consultant (Bausch + Lomb Technolas, Alcon, Nidek, Physiol)
