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P050034 The Implantable Miniature Telescope (IMT ™)

P050034 The Implantable Miniature Telescope (IMT ™). Presented by Bernard P. Lepri, OD, MS, MEd FDA/CDRH/ODE/DOED July 14, 2006. Special Thanks!. Gene Hilmantel, OD, MS – the Rosetta Stone of biostatistics

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P050034 The Implantable Miniature Telescope (IMT ™)

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  1. P050034The Implantable Miniature Telescope (IMT™) Presented by Bernard P. Lepri, OD, MS, MEd FDA/CDRH/ODE/DOED July 14, 2006

  2. Special Thanks! • Gene Hilmantel, OD, MS – the Rosetta Stone of biostatistics • Bruce Drum, PhD – the walking guide to visual science and contributor of the visual science slides of this presentation today.

  3. The proposed indication reads: The IMT™ is indicated for use in adult patients with bilateral, stable, untreatable, moderate to profound central vision impairment due to macular degeneration as determined by fluorescein angiography, and cataract in patients who

  4. Indications (continued) • are 55 years of age or older; • Have BCDVA of 20/80 to 20/800; • Have Adequate peripheral vision in the nonoperative eye; and • Demonstrate a minimum 5 letter improvement on ETDRS chart with an external telescope

  5. Study Design prospective, multicenter clinical trial 28 clinical sites conducted in the U.S. under IDE 218 consecutive patients were enrolled 206 patients were implanted and evaluated Mean age was 75.4 years ± 7.2 followed over a 24-month period 1 day, 1 wk, 1-, 3-, 6-, 9-, 12-, 18- and 24-month postoperatively.

  6. Effectiveness Endpoints • ≥2 lines BCDVA/BCNVA in 50% of eyes @ 12 mos. Postop – primary endpoint. • Quality of Life surveys (ADL and VFQ-25) - secondary measurements of procedure success.

  7. Safety Endpoints • Endothelial cell loss: Mean % ECD loss ≤17% at 1yr. postop – primary • average ECD loss; large-incision cataract surgery; reported in literature • ≤10% eyes lose ≥2 lines BCDVA or BCNVA without a gain of ≥2 lines in BCVA – secondary • Adverse events and complications – no preset targets.

  8. Clinical Safety Preop ECD ≥ 1600 Cells/mm2 Minimum ACD ≥2.5mm Minimum Age ≥55

  9. Mean Decrease in ECD (overall cohort) 25.3% at 1 year 28.2% at 2 years. 12.5% (CI: 7.6% to 19.0%) of eyes available at 2 years had ECD counts of <1000 cells/mm2 90th percentile @ 2 years (10% with greatest loss) was: ·        60% ECD loss - IMT-implanted eyes ·         12% ECD loss - fellow eyes.  

  10. Endothelial Cell Density Loss

  11. ECD Considerations • No morphometric data on ECD was presented by the sponsor. • High ACD loss – due surgical order; first three cases • Eyes with ACDs of < 3mm had the greatest losses at all time periods and especially at 24 months, where approximately 1/3 of ECD has been lost. • Surgical specialty – corneal surgeons had the lowest surgical loss rates

  12. ECD Considerations (continued) • 60 years old - 22 more years (82 years old) • 90 years old - 5 more years (95 years old) • Minimum acceptable level of ECD for future cataract surgery is 1500 cells/mm² • 800 cells/mm² - potential corneal edema

  13. Percentage of Eyes with Predicted ECD ≤1000

  14. ECD Loss Stratified by ACD

  15. ACD & Corneal Clearance • IMT is designed for a 2mm corneal endothelial clearance • Minimum ACD was ≥2.5mm • No substudies or data presented to establish suitability of minimum ACD for the established minimum clearance

  16. Haptic Placement

  17. Posterior Capsular Opacification • 1/174 (0.6%) @18 months • 2/147 (1.4%) @ 24 months. • Zero (0) YAG Capsulotomies • Needling - two patients with visually significant PCO.

  18. PCO Management • YAG capsulotomy can damage the IMT lenses. • Capsulotomy through the periphery of the telescope • No patient data available • Rabbit studies performed

  19. Potential Problems with YAG Procedures • Can only be done around the periphery of the IMT • Increases the # of bursts and total amount of energy delivered to the eye • Increases risk of Retinal Detachment • Posterior movement of the IMT

  20. Clinical Effectiveness • Visual Acuity • Quality of Life

  21. Categories of Vision Loss • Visual impairment – • BCDVA ≤ 20/40 but better than 20/200. • Legal blindness • BCDVA ≤ 20/200 • visual field diameter < 10 degrees. • Low vision < 20/60 in the better eye.

  22. Preop VA Values - IMT • The preoperative Acuity range was 20/80 - 20/800 • mean preop BCDVA - 20/312 • mean preop BCNVA • @ 8 inches - 20/315 • @ 16 inches was 20/262

  23. Implantation profile • 115 eyes were implanted with the 2.2X • 91 eyes were implanted with the 3.0X

  24. Improvement in Vision • Improvement of ≥ 2 lines BCDVA or BSNVA = 85% to 90% • Improvement of ≥ 2 lines BCDVA and BSNVA = 67% to 73% • 52.8% (102/193) gained ≥ 3 lines BCDVA and BCNVA

  25. VA Improvements ≥2 lines • 90.1% of implanted eyes were reported to have had an improvement of ≥2 lines in either BCDVA or BCNVA at 12-months postop. • Refractive devices – baseline ≥20/40

  26. Reliability of Low Vision Measures- Russell Woods and Jan Lovie-Kitchin

  27. Predicted EffectivenessDistance Visual Acuity

  28. Predicted EffectivenessNear Visual Acuity

  29. Adjusted vs. Actual Acuities? • IMT measured acuity will theoretically increase by ~3.4 or ~4.3 lines, respectively for the 2.2 & 3.0X • 2 line loss = 5.4 or 6.3 lines • improvement of <1.4 or 2.3 = a loss of >2 lines

  30. Safety & Effectiveness • Vision Rehabilitation • Functional Vision • Orientation & Mobility • Reading

  31. VFQ-25 - Items 5, 6, 7, 8, and 9 • Independent mobility, • Reading street signs and names of stores, • Negotiating steps and curbs, and • Reading ordinary print in newspapers.

  32. VFQ-25 • PMA reports mean scores and mean changes • FDA requested a frequency analysis for each rating within each category.

  33. Summary of Frequency Analysis of Items # 5, 6, 7, 8 & 9 • Subjects reporting extreme difficulty with the items pertaining to visual function decreased in number by one year postop. • Subjects reporting little and moderate levels of difficulty increased at one year. • It is unclear from the data reported whether some of the subjects who initially reported extreme difficulty subsequently reported moderate difficulty.

  34. VisionCare’s Rehab Program • Implemented by the patient with assistance from the family • Professionally directed Orientation and Mobility - not provided. • LV Reading Specialist Training – not provided. • No validated methods of measuring the outcomes of training.

  35. What is successful rehabilitation? A reduction in the level of difficulty in performing a particular task or goal, or the reduction in the importance of that task by teaching the patient alternative strategies to achieve the goal. • Massof,RW. A system model for low vision rehabilitation. I. Basic concepts. Optom Vis Sci. 1995 Oct; 72(10): 72-36.

  36. Is professional vision rehab necessary? • Failure rate decreased from 22% to 3% with training according to Langman et al. 1944 • A survey (@ 12 and 24 months) of 200 veterans using 740 low vision aids found that 85.4% of devices were still in use. • 85.4% of 200 Veterans were found to still be using their optical assistive devices 2 years later - Watson et al. 1997 • 77% of 261 cases used optical devices successfully - Van Rens et al. 1991 • Improves patient independence, performance of ADLs, and quality of life – Fletcher et al. 1991, 1994

  37. VISUAL LOSS AND FALLS • Nevitt et al reported a threefold risk for multiple falls with poor vision. • 25% to 35% annually of older persons fall • >40% result in hospitalization. • Beaver Dam Eye Study • ≥60 years of age • 11% (943) of 2365 with acuity < 20/25 • 4.4% with normal visual acuity had experienced a fall in the prior year.

  38. Adverse events - Falls • 8 non-ocular adverse events occurred during this trial

  39. Effects of Magnification • magnification alters proprioceptive senses: • judgment of relative distances • location objects in the visual space • ability to walk and to read • judgment of depth of steps and curbs

  40. Central & Peripheral Vision • IMT implanted eyes – Central • Fellow eye – Peripheral • No direct performance measures for shifting binocular suppression from one eye to the other.

  41. Binocular Performance • Non-correspondence of overlapping fields forces binocular rivalry and suppression • Severe visual field restriction in the (dominant) IMT eye • Motion discrepancies in magnified and unmagnified fields • Possible suppression of entire fellow eye

  42. 10° 20° 30° 40° 50° 60° 70° 80° 90° Normal Monocular Field (OD) Superior Left Right Inferior

  43. Normal Monocular Field (OS) Superior Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Inferior

  44. Normal Binocular Field Superior Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Inferior

  45. Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Binocular Field for Macular Degeneration Patients Superior SC Inferior

  46. Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Subjective Field of IMT Eye Superior SC Inferior

  47. Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Objective Field of IMT Eye Superior Inferior

  48. Left Right 10° 20° 30° 40° 50° 60° 70° 80° 90° Monocular Field - Fellow Eye Superior SC Inferior

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