TESA (The Eye Scan App) is a product of Sight4All, a Columbus, Ohio-based digital health company that develops and markets innovations in eye care technologies. ​Sight4All looks to be a difference-maker. The company’s goal is to develop new, safe, effective, and affordable ways to bring significant improvements in vision diagnostics for licensed eye care providers. ​Sight4All is re-thinking vision care— how it happens, where it happens, and how it can become accessible worldwide.

What is TESA Being Designed to do?

TESA turns an iPhone 7+ or the latest Android phone into two valuable tools to help licensed eye care providers better serve their patients:

1. Autorefractor– Measures SPH, CYL, AXIS, ADD in less than one second per eye.

​           The U.S. Patent Office provided a notice of allowance for Sight4All’s autorefractor technology to have a patent in October 2018.

2. Digital Cover Test– Distinguishing between phoria and tropia, TESA provides the direction of eye misalignment

(eso/exo; hyper/hypo) and states the measured magnitude in prism diopters. Phoria and tropia be taken in any direction of gaze. 

​           The U.S. Patent Office approved Sight4All’s eye misalignment technology to have a patent in May 2017.

NOTE: Sight4All acknowledges that TESA is in no way a substitute for a face-to-face vision and eye health exam by an eye care professional

How does TESA Work?

TESA is an simple app requiring no other device, apparatus, light source or sensor.

Just download it to an iPhone 6+.

Take a picture of the eyes and TESA’s proprietary algorithms do the rest.

​TESA technologies are not mere miniaturizations of existing technologies. Instead, TESA’s patented technologies are novel methods developed by Melissa Bailey, OD, PhD and The Ohio State College of Optometry.


Sight4all has exclusive licenses for multiple patents developed by Dr. Melissa Bailey at The Ohio State University.

These include:

1. Automated Detection of Eye Alignment, US, Utility Patent Granted April 2017

2. Method and Apparatus for Making a Determination About An Eye In Ambient Lighting Conditions, US, Filed November 2015

3. Measurements Using A Single Image Capture Device, US, Filed March 2016

All are available for sublicensing.