Framework for Teaching the Use of Prisms Low Vision Therapist and O&M Specialist Collaborate 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Training The Framework for Teaching the use of Prisms is a Worksheet for checking and tracking the introduction of skills needed for successful use of Prism glasses. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Following the Framework Facilitates: Training in-office to functional settings Collaboration between the LVT and COMS Analyzing Post-training issues Patient understanding through a hierarchy of tasks 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Basic Training Components Traditional training components used in a hierarchy 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Basic visual motor skills: Scanning: use of head and eye movements to search for targets Tracing: follow stationary line Tracking: visually following a moving target Source: Geruschat, D. & Smith, A.J., (1999) Low vision and mobility In Blasch, B., Wiener, R., & Welsh, R.L. (Eds.) Foundations of orientation and mobility, second edition (60-103) New York: AFB. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Instructional program and hierarchy for use of the prism Patient is stable; object is stable Patient is stable; object is moving Patient is moving; object is stable Patient is moving; object(s) is/are moving Source: Brilliant, R. (1999) Essentials of Low Vision. Boston: Butterworth Heinemann 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Why Do We Need Such A Long Checklist? Teaching New Behavior: Traditional Scanning Techniques Optical Device Training: Prism Therapy – Adapting to Image Displacement 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Why Do We Need Such A Long Checklist? Patient Awareness of field loss Assess Current Scanning Behavior Head Movements Eye Movements Prism Education Prism Adaptation Safe Travel Follow up 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Case Discussions Mr. A: Right Heminanopic Field Loss (HFL): Occluding one eye which he believed was blind Mr. C: Bilateral inferior field loss: None Mr. E: Left HFL: Avoids walking in congested environments Mr. B: Incomplete right HFL: Repeatedly being hit on the right side of his head by doors. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Complications Cognitive – Understanding & Retention Motivational – Learning new behavior and time commitment Psychosocial Issues – Housing & Emotional Medical Conditions – HBP, Orthopedic issues, etc. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Ophthalmic Prisms 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Ophthalmic Prisms This presentation discusses the use of prisms for people with a hemianopic field loss for which we use Full Field Prism Glasses. Relocates or shifts an image into an area of residual vision The amount of prism is a measurement describing the degree of shift or relocation of an image. The higher the amount of prism, the more the image is shifted. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Full Field Prism With a hemianopic field loss, a full field prism will have the base out towards the defect. A person with a right hemianopsia will have prism glasses with both bases right. A person with a left hemianopsia will have both bases left. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Base towards defect This would be true of Full Field Prisms Fresnel Prisms Hemi Prism Peli Prism 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Full Field versus Hemi Prism The training of a full field prism differs slightly from a hemi prism. Full Field Prism Emphasis on adaptation through Reaching Tasks. Hemi Prism Emphasis on eye rotation and head turn towards object. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Reaching Tasks Emphasized with Full Field Prisms because the person’s straight-ahead gaze is through a prism. The purpose is to educate and adapt to the shift of the image (usually mid-line) of an object. The facilitator will hold objects in the peripheral field and ask the person to point or grasp the object until they perform the task with out error. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Eye Rotation and Head Turn With a Hemi Prism, the person’s straight-ahead gaze is through a carrier lens without Prism. The Hemi Prism is accessed by an ocular turn into the prism (placed in the area of the field loss) creating an awareness that an object is there. Once the object is spotted, the person needs to turn their head to view the image through the carrier lens to get a clearer view of the image. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Benefits of Using Prisms Our clinic has found that, with a number of people, teaching of basic visual scanning skills and instruction for using prism glasses, decreased the reported number of critical incidents. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Some Disadvantages Visual acuity is reduced when viewing through a prism A Hemi prism creates a blind spot at the edge of the prism. The higher the power of the prism the larger the spot. It creates an effect sometimes referred to as “jack-in-the- box” with the image suddenly appearing. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Some Disadvantages There are reflections – some described seeing colors –especially yellow There is a reduction in contrast And, finally the reason we created a Framework: Lots of Patient Education and Training. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Goals of Training Adapting to a hemianopic field loss using an optical device that shifts images into the residual field Measures of Success: Percentage of time they wear the device Correction of functional complaints (i.e. being hit by doors, avoiding certain environments) 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Hemianopic Field Loss Patients don’t always understand the nature and functional limitation of their vision loss. Mr. A. Reported occluding his right eye, reporting that there is “no vision in this eye” and the left eye is unaffected. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Static Training Correct any misconceptions the patient has about his field loss. Design a visual pattern that can reinforce the degree of field loss Introduce basic visual skills Introduce Prism Glasses Begin Adaptation exercises 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

The Advanced Low Vision Clinic at the VA NY Harbor Health Care System Static Visual Field Assessment – 1. Understanding the Field Loss Pt. understanding of Field loss: a.Diagrams, simulators b.Near tasks using deck of cards c.Occlusion – Evidence that both eyes have some vision d.Designing a pattern of visual targets to practice head turns and eye turns- Evidence that the patient is missing some information e.Discuss measuring the head turn in relationship to a shoulder f.Record observations for COMS 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

The Advanced Low Vision Clinic at the VA NY Harbor Health Care System 2. Describe and Record head movements: a.Observation of head movements: no movement slow movements quick movements b. Pointing to objects in the outer most field (highest, lowest, left, right) c. Estimate of degree of head turn to find “missing objects” d.Describe head turn in relationship of head to shoulder 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

The Advanced Low Vision Clinic at the VA NY Harbor Health Care System  Describe visual scanning pattern used – Looking for signs and numbers (Circle appropriate description): Static head posture: downward upward left right Scanning: None occasionally frequently Pattern: Random Systematically Time: quickly timely slowly AER Cleveland, 2011 S. Barnard & M. Beck

Introduce prism glasses to patient: Reaching Tasks Observing Displacement Assess Adaptation 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

What Is Adaptation? They demonstrate this by accurately pointing, reaching and touching stationary then moving objects. We consider adaptation occurring when the patient consistently demonstrates accurate object dislocation while wearing prisms. 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Dynamic Training Begin in a quiet location, such as a hallway Locate targets placed in the patient’s field deficit; they must move their head to locate the object Progress to more complex environments Reinforce compensatory scanning strategies Patient GOAL: turn head into the field loss Scanning may reduce the blind area formed from the placement of the prism 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Dynamic Training continues… Moving displacement and relocation; identifying by scanning It is like using the side mirror on a vehicle 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Long cane The long cane can be used to enhance visual efficiency. The COMS teaches goal-specific visual scanning behaviors (gridline, perimeter, etc.). 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Case Discussions 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Framework for Teaching the Use of Prisms Questions? 10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

Sources Blasch, B., Weiner, W., & Welsh, R. (Eds.). Foundations of Orientation and Mobility, 2 nd edition. New York: AFB Press, Brilliant, R. (1999). Essentials of low vision. Boston: Butterworth Heinemann. Cicerone, K. D., Dahlberg, C., Kalmer, K., Langenbahn, D. M., Malec, J. F., Bergquist, T. F. et al. (2000). Evidence-based cognitive rehabilitation: recommendations for clinical practice. Archives of Physical Medicine Rehabilitation, 81, Houston, K., Eldred, K., & Mennem, T. (2010). EnVision Conference Proceedings, Sept. 22, 2010, Workshop on prism adaptation therapy for left hemispatial neglect after stroke or brain injury. San Antonio, TX. O’Neill, E.C., Connell, P., O’Connor, J. C., Brady, J., Reid, I. & Logan, P. (2011). Prism therapy and visual rehabilitation in homonymous visual field loss. Optometry and Vision Science. 88, Perez, A. & Jose, R. T. (2003). The use of Fresnel and ophthalmic prisms with person with hemianopic visual field loss. Journal of Visual Impairment and Blindness, 97, Chadwick Optical (2011). How Prisms Work. Retrieved May 2011 from /17/2015 AER Cleveland, 2011 S. Barnard & M. Beck

10/17/2015 AER Cleveland, 2011 S. Barnard & M. Beck