Fitting Peripheral Prisms for Patients with Hemianopia Eli Peli, MSc, OD, FAAO Professor of Ophthalmology, Harvard Medical School Moakley Scholar in Aging Eye Research Please silence all mobile devices and remove items from chairs so others can sit. Unauthorized recording of this session is prohibited. Disclosure Statement: Patents, Consulting, Funding of Research The workshop is sponsored by Chadwick Optical, Inc. OS Field 2011, Eli Peli, Schepens Eye Research Institute 2011, Eli Peli, Schepens Eye Research Institute OS Fiel d OD Fiel d 2011, Eli Peli, Schepens Eye Research Institute 2011, Eli Peli, Schepens Eye Research Institute 1
OU Field OS Fiel d OD Fiel d Optic Chiasm Post Chiasmal Lesion 2011, Eli Peli, Schepens Eye Research Institute OU Field Vision with Hemianopia OS Fiel d OD Fiel d Post Chiasmal Lesions Cortical Lesion 2011, Eli Peli, Schepens Eye Research I tit t RNIB London Typical Static Simulation Visual scene with normal field Visual scene with left HH 2
Visual scene with gaze left Visual scene with further left gaze Visual scene with extreme left gaze Visual scene with gaze center Visual scene with gaze right Outline Prior Approaches and their Limitations The Peripheral Prisms and Their Use Clinical Trials Evaluating the Use of P Prisms Fitting the Peripheral Prisms Training Patients in the Use of the Prism Oblique Prisms Fitting Fitting the Prisms - Hands-on Training 3
Prior Prism Approaches and their Limitations Binocular Overall Prisms Yoked Prisms Field shift only No field gained Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision 1996 Why only 20 Higher power Larger effect Heavy and thick lenses Poor image quality Unacceptable foveally even with ophthalmic prism Worse with Fresnel Bilateral Sector Prisms Right Hemianopia Bilateral Sector Prisms Prism on both lenses prism base to the field loss Prism on half of lenses Most positions of gazeno effect at all Apical Scotoma with Bilateral Sector Prisms Optical Blind Spot- Apical Scotoma On right gaze - only shift image Do not expand the field Right Hemianopia Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision 1996 4
Apical Scotoma in Any Prism With Binocular Sector Prism looking straight ahead With Right Hemianopia With Right Hemianopia Without Prism looking to the right With Prism looking to the right Apical Scotoma- Optical Blind Spot With Right Hemianopia With Right Hemianopia 5
Unilateral Sector Prisms Using Fresnel Press-on Prisms 3M Prism on one lens only on side of the field loss Most positions of gazeno effect at all Unilateral Sector Prism Right Hemianopia On right gaze -? Right Hemianopia Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision, 1996 Just Flipped for Left Hemianopia Unilateral Sector Prism Left Gaze Left Hemianopia Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision, 1996 Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision 1996 Unilateral Sector Prism Left Gaze OS only Field Expansion Prism Eye PP PP Diplopia Central Disturbing Magnitude of effects Annoying illustrated is incorrect Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision 1996 OD only OS view Blocked by Apical Scotoma. Immaterial seen without and with prism Visual Field With Large Gaze Shift Computed With 20 Sector prisms Gaze shifted 20 into the Prism Expanded Field Diplopia 6
View with gaze center With unilateral sector prism 20Δ View of scene with gaze right No effect of prism No effect of prism View with gaze center View with 20 gaze left No Prism No effect of prism View with 20 gaze left into prism Diplopia Expansion PP 10 Most Saccades are Less than 15 Magnitude of Gaze Shift PP Gaze Shift Gaze Shift- PP PP Cohen, J.M. & Waiss, B., Visual Field Remediation, Chapter 1, Remediation and Management of Low Vision 1996 What happens if gaze shift is Less than 10? 7
Visual Field Unilateral Sector Prism View with gaze center Computed With 20 Sector prisms Expanded Field Central Scotoma Gaze shifted 5 into the Prism No effect of prism View with 11 gaze left No Prism View with 5 gaze left into prism (11 Gaze shift) Where is the Apical Scotoma? Expansion Prism is 2 mm left - 6 left Note apical scotoma Limitations of Prior Approaches Most positions of gaze unaffected by prisms Requires scanning to blind side Diplopia in central vision Annoying and disturbing Apical scotoma in central field Do no harm? Acuity limits prism power centrally Expansion limited to 10 Peripheral Prisms and Their Use 8
Hemianopia and no Strabismus Hemianopia with Exotropia Right Hemianopia with Right Exotropia Right Hemianopia Field Expansion Reported in Congenital Hemianopia Panoramic vision Hemianopia and Exotropia About 24 cases of teenagers many with documented ARC reported Surgeons usually do not operate on exotropes with hemianopia Works also with esotropia of the other eye One such teenage case reported I have seen 2 more Right Hemianopia with LEFT Esotropia Field Expansion with Small peripheral loss with Diplopia Except if ARC Hemianopia with Esotropia Turn Hemianopes to Exotropes? No surgery needed We know how to do it with a simple prism Problem - Exotropia causes double vision Adults do not develop ARC Diplopia and Confusion are unacceptable in central vision Field Expansion Solution Make Hemianopes Strabismic Diplopia is a problem Double vision peripherally, easy to adapt Physiological Diplopia 9
Horopter Zone of single binocular vision Peripheral Prisms Peripheral Unilateral Prism Left Hemianopia Peripheral Prism Horizontal Design 3M press-on 40 prism segments on upper & lower parts of carrier lens Visual field expansion measured by Goldman perimetry Binocular visual fields - Left hemianopia Users always look through central, prism-free area; No central diplopia Prisms on left lens Base left for left hemianopia Without peripheral prisms With 40 peripheral prisms Properties of Peripheral Prisms High prism power possible in periphery (57 Expand upper and lower fields by up to 30 (even more) Double vision is limited to periphery Maintain single central vision Double vision (confusion) peripherally, easy to adapt Apical scotoma limited to periphery Apical scotoma reduces diplopia All positions of gaze affected by prisms Only with Press-On with inside lens configuration With 57 gets 30º expansion Calculated Measured Apfelbaum, Ross, Bowers, Peli (2013) Considering apical scotomas when prescribing prisms for homonymous hemianopia.translational Vis.Sci. & Technology 10
View with Left HH No prism Peripheral prism with gaze center No Diplopia Expansion (confusion) Properties of Peripheral Prisms High prism power possible in periphery (57 Expand upper and lower fields by up to 30 (even more) Double vision is limited to periphery Maintain single central vision Double vision peripherally, easy to adapt Apical scotoma limited to periphery Apical scotoma reduces diplopia All positions of gaze affected by prisms Only with Press-On with inside lens configuration No Escape from the Apical Scotoma Properly designed apical scotoma prevents diplopia in primary gaze 57 30º Properties of Peripheral Prisms High prism power possible in periphery (57 Expand upper and lower fields by up to 30 (even more) Double vision is limited to periphery Maintain single central vision Double vision peripherally, easy to adapt Apical scotoma limited to periphery Apical scotoma reduces diplopia All positions of gaze affected by prisms Not really Only with eyeward prism serration (EPS) configuration Works at Any Position of Gaze Gaze 15 left True only for EPS configuration Gaze 15 right Works but effect is small 11
View with gaze center-peripheral prism View with 5 gaze left-peripheral prism Increased field & some distortion Expansion (confusion) Expansion (confusion) Jung JH, Peli E (2014) Impact of high power and angle of incidence on prism corrections for visual field loss, Optical Engineering View with 20 gaze left-peripheral prism Improve Image Quality Safety & Cosmesis Minimal Increased field peripherally. It is limited by TIR Total Internal Reflection Permanent Prism Solid PMMA Fresnel European Permanent Prism in 40Δ or 57Δ Improved Cosmetics and Safety // 12
Better cosmetics with sun clip-on Clinical Studies and Clinical Trials Completely invisible // Evaluations of peripheral prisms Long-term benefit in obstacle avoidance for at least 50% of wearers in: Case series report 1 Laboratory extended wear trial 2 Multi-center clinical trial 3 Independent clinical study 4 All with 40Δ prisms 1. Peli E. (2000) Optom Vis Sci. 77:453-464. 2. Giorgi RG, Woods RL, Peli E. (2009) Optom Vis Sci. 86: 492-502 3. Bowers AR, Keeney K, Peli E (2008) Arch Ophthalmol 126, 657-664 4. O'Neill, E. Connell, et al. (2011) Prism therapy and visual rehabilitation in homonymous visual field loss Optometry and Vision Science Community-Based Multi-Center Study Long-term follow up to evaluate: Fitting procedures Patient acceptance Functional utility Preliminary evaluation of permanent prisms Main outcome measures Minimum inter-prism separation Long-term success rate (continue to wear) Helpfulness for obstacle avoidance Community-Based Multi-Center Study 60 patients screened in 18 clinics Complete hemianopia, no neglect 5 excluded, 12 withdrew pre-fitting 43 fitted with prisms Determine minimum inter-prism separation tolerated for walking Tolerated = comfortable single central vision with no change in head posture between without and with prisms Of the 43 that were fitted 32 (74%) continued wear after week 6 follow up 21 (49%) continued long term wear (median 12 months) Success rates varied between clinics More patients higher success rate Section cut out for spot reading X 13
Final prism fitting positions Number of patients 12 10 8 6 4 2 0 7 8 9 10 11 12 13 14 Interprism separation (mm) An inter-prism separation of 12mm adopted for a simplified fitting protocol Bowers et al. Archives of Ophthalmology, 2008 Fitting the Peripheral Prisms Demonstration Need a Volunteer Basic Fitting Protocol Frame selection and fitting Adjustable nose pads Fitting well and does not slip At least 36mm in the vertical B dimension At least 18mm from pupil center to upper eye wire Upper eye wire at about the level of eyebrow At least 18mm from pupil center to lower eye wire 23mm for bifocals Evaluated in Second Multicenter Clinical Trial Using a cling-on single piece template Template has a fixed inter-prism separation of 12mm Initial Fitting Position Mark pupil center on demo lens Copy the center mark to back of the lens Center the Template on pupil position Laterally and vertically This is the initial fitting position Rub template well in the center to improve optical quality Initial Fitting Position 14
Degrees and mm 1 deg is about 0.35 mm on carrier lens 1 mm 3 degrees Initial position of template Prisms are placed 6 mm above and below pupil About 16.5 degrees above and below Adjusted Position Observe head posture while walking-no prism Place an occluder in front of the fellow eye Explain that black patches represent locations of prism segments in the real glasses Can use prism in place of black patch Explain lack of Rx correction in demo lenses Place glasses on patient and take for a walk Changes in head posture observed? Interference of patches noted by patient? Adjust Template position up or down as needed Prisms Position Effect on Head Posture When Walking Tolerated = comfortable single central vision with no change in head posture between without and with prisms Observe head posture when walking without template or prism Initial prisms position is 6mm above and below pupil center Observe head posture when walking with template or prism Do not forget to cover the other eye Lower Template or Prism Position Lower position 2 mm at a time Observe head posture when walking Move down until causes problem Observe head posture when walking with lower prisms position Expected change in head posture? Causing double vision? If using prism instead of template Higher Template or Prism Position Raise position 2 mm at a time Observe head posture when walking Move template up until causes problem Observe head posture when walking with higher prisms position Expected change in head posture? Causing double vision? If using prism instead of template 15
Verify sufficient clearance for structural integrity (3mm) Determine final position Clearance should be > 3mm Marked on Template If needed shift template temporally but not more than 3mm When satisfied secure template in position with a tape Can you increase the field expansion by shifting prism temporally towards the field loss?? No! Field expansion is determined by prism power Shifting Prism Temporally is Not Helpful Upper segment shifted temporally 5 1.75 mm Temporal prism shift Upper segment shifted temporally 15 5 mm Apex Scotoma Shifted Centrally With 57Δ OPS Shifting Prism Temporally Increases Possibility of Spurious Reflection Shifting Prism Nasally Increases Diplopia Nasal prism shift Upper segment shifted Nasally 5 1.75 mm Jung JH, Peli E (2014) Impact of high power and angle of incidence on prism corrections for visual field loss, Optical Engineering Apfelbaum, Ross, Bowers, Peli (2013) Considering apical scotomas when prescribing prisms for homonymous hemianopia. Transl. Vis. Sci. & Technology 16
Simulating the Monocular View with High Power Prisms Gaze 10 Left Simulating the Monocular View with Different Configurations Gaze Center OPS 57Δ Outward Prismatic Surface Diplopia Scene field-of-view at primary gaze EPS 57Δ Eyeward Prismatic Surface Jung JH, Peli E (2014) Impact of high power and angle of incidence on prism corrections for visual field loss, Optical Engineering Simulating the Monocular View with Different Configurations OPS 57Δ Gaze 20 Left Gaze 10 Left EPS 57Δ Eyeward Prismatic Surface Template position can be used to fit Temporary Pre Cut Prisms or Permanent Prisms Newer Design Oblique Peripheral Prisms Pre Cuts speed up fitting and may be use without template once experienced Specifically for Driving 17
Binocular Perimetry Oblique Prisms Without Prisms Left hemianopia With Prisms Field of view through windshield Peli E. (2008) Peripheral Field Expansion Device. US patent #7,374,284 Oblique peripheral prism glasses Visual field expansion Binocular visual fields - Left hemianopia High Power Oblique Prisms With horizontal prisms Field of view through windshield Field expansion in area relevant to driving With 40 Oblique prisms We now have 57Δ peripheral prisms 40 providing 22º expansion 57 providing 30º expansion 57 Oblique Prisms tilted at 25 Placebo-Controlled, Crossover Trial of Real and Sham Prism Glasses Two treatment groups Real oblique and sham horizontal Real horizontal and sham oblique Order of real/sham counterbalanced Real 57 oblique Sham <5 horizontal 18
Main Results 73 Enrolled 61 completed the cross-over 37 (61%) clinical decision to continue wear No difference between oblique and horizontal 25 (41%) still wearing at 6 months Bowers, Keeney, & Peli (2014) Randomized crossover clinical trial of real and sham peripheral prism glasses for hemianopia JAMA Ophth. Comparison questionnaire If you were only allowed to keep one pair of glasses, which would you choose? First pair? Second pair? Neither? Comparison questionnaire Which pair of glasses would you choose? Percent of patients complete crossover 100 80 60 40 20 0 p < 0.001 26% chose sham Real Sham Neither Emphasizes the importance of including a control condition Comparison questionnaire Which pair of glasses would you choose? Reasons for choosing real or sham Percent "yes" responses 100 80 60 40 20 0 Chose real p = 0.005 More helpful when walking Chose sham Vision more comfortable On-road driving with prisms study Three routes, each ~ 1 hour Busy streets in Ghent, Belgium Dual-control car Two evaluators: Examiner of the Belgian Road Safety Institute Back seat evaluator On-road driving - Procedures One pre-fitting on-road test without prisms Two post-fitting on-road tests With sham prisms (oblique) With real prisms (oblique) Evaluators masked Bowers, Tant & Peli (2012) A pilot evaluation of on-road detection performance by drivers with hemianopia using oblique peripheral prisms. Stroke Research and Treatment, Article ID 176806. 19
Satisfactory responses to unexpected hazards p < 0.01 100 80 60 40 20 0 No Sham Real Prism Prism Prism Satisfactory = Score of 4 or 5 Error bars = 95% confidence Percent Satisfactory Interventions by driving instructors: brake, gas, steering Number 12 8 4 0 Blind side No Prism Sham Prism Seeing side Real Prism Fewer blind-side interventions with real prisms Fewer is better here Recent driving simulator study Pedestrian on a Collision Course Slow Motion Horizontal field of view 225 Houston et al (2016) A pilot study of perceptual-motor training for peripheral prisms Translational Vis. Science & Technology Pedestrian on a Collision Course Normal Motion Blind side pedestrian detection rates In the driving simulator With prisms (%) Detection rate (%) - With prisms 100 80 60 40 20 0 0 20 40 60 80 100 Without prisms (%) Houston et al (2017) Driving with hemianopia VI: peripheral prisms improve blind-side detection in a driving simulator TVST, Submitted 20
Blind Side Pedestrian Detection Rate Before Training Detection rate (%) - With prisms With prisms (%) 100 80 60 40 20 0 0 20 40 60 80 100 Without prisms (%) Blind Side Pedestrian Detection Rate After Training Detection rate (%) - With prisms With prisms (%) 100 80 60 40 20 1 week 0 0 20 40 60 80 100 Detection Without rate (%) prisms - Without (%) prisms Blind Side Pedestrian Detection Rate 3 Months After Training Detection rate (%) - With prisms With prisms (%) 100 80 60 40 20 1 week 0 3 months 0 20 40 60 80 100 Detection Without rate (%) prisms - Without (%) prisms Training Patients in Use of the Prism In-office training Demonstration of expansion effect Binocular confrontation visual fields Head turning Fixate objects detected via prism image through the clear carrier section Demonstration of undesirable central diplopia Reach-and-touch exercise Familiarization with shifted directions of objects Wear prism glasses as much as possible Except driving and extended reading Home training instructions Wear prism glasses as much as possible Except driving and extended reading Practice use first in familiar environments Gradually expand range & complexity Always have a companion when expanding range first Take other glasses with you in case of need to remove Practice reach and touch exercises Use head movement when not exercising 21
New Fitting Designs FitOvers Peripheral Prisms FitOvers over Rx glasses Less expansive; Provides Rx for prism Wearing normal Rx glasses FitOvers over Rx glasses One size may not fit all well; Too low here Provides Correction also through prism Magnetic Clip-On Glasses Magnetic Clip-On Prisms Can be bifocal/pal Rx through prism; Inexpensive to change Rx 22
MultiLens, Sweden - Hang On Rx through prism; Inexpensive to change Rx Higher Power Prisms Needed to support detection of other pedestrians in open space environments Maximum risk from such pedestrian is at eccentricity of 45º Current prisms are 30º Peli et al. (2016) The risk of pedestrian collisions with peripheral visual field loss J. of Vision High power without the limitation of the TIR Bi-Part Prism Needed to enable effective scanning to the blind side Peli et al. (2016) High power prismatic devices for oblique peripheral prisms Optometry and Vision Science Bi-part: Higher power With a gap Which is better? 45 prisms monitor 46% of potential collisions Mirror-Based Prism-like device Wide shift, Narrow field Cascade to widen the field 57Δ Lower power No gap 30 prisms monitor 26% of potential collisions Cascade converges rapidly limiting field width Peli E. Peripheral Field Expansion Device. US patent 7,374,284 2008 23
The Latest and Greatest! Novel design overcomes the convergence limitation Provides many other advantages Wide field High power High deflection 45º and more Low distortion level Dramatic image quality To be disclosed & demonstrated at workshop Panoramic Street View View with Upper Peripheral Prism 57Δ (30 ) Fresnel Mirror-based (45 ) Pictures of the Novel Peripheral Prisms To be available at the workshop Workshop Equipment & Supplies All provided by Chadwick Optical What is in your personal kits is yours to keep Demo glasses, demo clip-ons, tools etc. are provided for the workshop use only Please, do not take anything that is not in your kit More Information Find it all on our web site http://serinet.meei.harvard.edu/faculty/peli/ Also on Chadwick Optical web site http://www.chadwickoptical.com And on http://www.hemianopia.org MA Medicaid is paying $650-$750 for a pair of these 24