“The eyes are the window to the soul,” according to a proverb. For eye care practitioners, this bit of ancient wisdom has particular resonance. By examining a patient’s eyes either with diagnostic equipment or simply eye to eye, a lot can be learned about someone’s physical, emotional and even spiritual state.

Yet technological advances in the field of marketing research reveal that the eyes are a window to much more. As I recently learned, a Swedish company called Tobii is introducing specially designed glasses that track a person’s eye movements while they’re shopping in a store. The geeky but sleek looking Tobii glasses are equipped with non-prescription lenses that have an infrared coating. The lenses are connected to sensors in the frame that communicate with IR markers located in “Areas of Analysis” (AOAs) on store shelves. The glasses then relay the eye tracking data to special data mapping software that keeps track of multiple AOAs to determine exactly where the shopper has been looking and what products they are seeing. Presumably, marketers could use this data to better understand consumer behavior and then package and display products in a more “eye catching” way.

We won’t be seeing Tobii glasses in optical dispensaries unless some enterprising optical retailer uses the system to analyze eyewear sales. However, they provide an interesting parallel to the way the optical industry uses eye tracking technology. Ophthalmic lens manufacturers have long used eye tracking to design lenses, and some new digital dispensing systems track a patient’s eye movements—and, in some cases, head movements, too. This biometric data about the patient’s viewing behavior is then combined with their prescription to design and produce personalized lenses.

The point is that our eyes provide a wealth of information not just about how and what we see, but what others see in us. In other words, there’s more to our eyes than meet the eyes.