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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



Product Risk Disclaimer

Bernell's Commitment to Safety and Quality:

As a dedicated provider of ophthalmic solutions, Bernell categorizes this product as a low-risk Class I medical device, designed with your safety and well-being as our top priority. Our rigorous quality control processes and comprehensive risk assessments aim to ensure the highest standards of safety and efficacy for our users.

Understanding the Risks:

While we are proud to report that there have been no documented adverse reactions associated with this product, we acknowledge the inherent truth that no product is entirely devoid of risk. It is our duty to inform and educate our users about the responsible use of our products to minimize potential risks.

Guidelines for Safe Use:

For your safety, Bernell strongly advises against the use of any of our products that may impair or diminish vision during activities requiring clear and unobstructed sight. The safety and health of our customers and their patients are paramount, and as such, we recommend that any application of this product be undertaken following the guidance of a qualified healthcare professional.

Your Role in Ensuring Safety:

We believe in the power of community and the importance of your feedback. Should you encounter any adverse effects or have safety concerns related to the use of our products, we implore you to reach out to our Customer Service Team immediately. You may contact via phone at 574-259-2070 during regular business hours, or email info@bernell.com. Your reports are crucial for us to conduct thorough investigations and take appropriate actions to uphold our commitment to product safety and quality.


EU Authorized Representative (EAR):

MedEnvoy Global B.V.
Prinses Margrietplantsoen 33 - Suite 123
2595 AM The Hague
The Netherlands

Additional Regulatory information can be found by clicking here



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. Although we at Bernell choose to sell our products exclusively to healthcare professionals as they are our target market, we strongly advise that anyone who may come across our products on a secondary market consult with a qualified healthcare professional before using any product. Additionally, we do not offer instructions for intended use, nor make claims for healthcare professionals, in how to diagnose, treat, cure, or prevent any disease or medical condition with our products. The majority of the items offered under vision therapy or vision training categories on this site fall under the FDA's General Wellness: Policy for Low-Risk Items. For safety reasons, we do not condone the use any of our products that occlude or restrict vision in any way while participating in activities that may require unrestricted vision.


Call Toll Free 1-800-348-2225 or (574) 259-2070

Fax to (574) 259-2102 or (574) 259-2103