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Bernell Tannen Flipper™


Item #: BTFLIP

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Distance horizontal fusional vergence facility (DFF) is often found to be reduced in many post-concussion patients. Dr. Barry Tannen has extensively studied this issue and developed a simple, yet effective test that doubles as a training tool for addressing this common challenge.

Introducing the specialized prism flipper, featuring 2PD Base-In (BI) on one side and 4PD Base-Out (BO) on the other. The flipper package includes a distance target and comprehensive instructions for effectively testing your patients. For your convenience, a quick reference guide is also printed on the back of the laminated target card.

Utilize these innovative prism flippers to:

  1. Assist in diagnosing distance fusional instability
  2. Monitor the recovery progress of distance fusional instability
  3. Aid in training and improving distance fusional facility


Kit Includes:
- Bernell Custom Prism Flipper with (2) 1PD Base-In Lenses (2PD Range) on one side and (2) 2PD Base-Out Lenses (4PD Range) on the other side

- Laminated Target Card with letter sized for 15ft testing distance plus Quick Instruction Guide on back

- Instruction Sheet

Research Articles:

Tannen, B., Rogers, J., Ciuffreda, K. J., Lyons, E., & Shelley-Tremblay, J. (2016). Distance Horizontal Fusional Facility (DFF): A Proposed New Diagnostic Test for Concussion Patients. Vision Development & Rehabilitation, 2(3), 170-175. Click here to read the article



Disclaimer: Please note that the products offered on our website have not been evaluated or reviewed by the United States Food and Drug Administration (FDA), unless explicitly stated otherwise. The information provided on this website is for informational purposes only and is not intended to diagnose, treat, cure, or prevent any disease or medical condition. The products offered on our website are not intended to replace or substitute any advice, diagnosis, or treatment provided by a qualified healthcare professional. It is strongly encouraged that any use of our products in an effort to improve visual skills only be done so under the guidance and supervision of a qualified healthcare professional.


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