P050034 The Implantable Miniature Telescope (IMT™) Presented by Bernard P. Lepri, OD, MS, MEd...
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Transcript of P050034 The Implantable Miniature Telescope (IMT™) Presented by Bernard P. Lepri, OD, MS, MEd...
P050034The Implantable
Miniature Telescope (IMT™)
Presented by Bernard P. Lepri, OD, MS, MEd
FDA/CDRH/ODE/DOEDJuly 14, 2006
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.
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
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
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.
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.
Safety EndpointsEndothelial 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.
Clinical Safety
•Preop ECD ≥ 1600 Cells/mm2
•Minimum ACD ≥2.5mm
•Minimum Age ≥55
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.
Endothelial Cell Density Loss
0%10%20%30%40%50%60%70%80%90%
100%
EC
D lo
ss >
20%
3 mth 12 mth 18 mth 24 mth
IMT eyesFellow eyes
ECD Considerations
No morphometric data on ECD was presented by the sponsor.High ACD loss – due surgical order; first three casesEyes 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
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/mm²800 cells/mm² - potential corneal edema
Percentage of Eyes with Predicted ECD ≤1000
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
2 years 3 years 4 years
IMT
Fellow
ECD Loss Stratified by ACD
Postop Interval
Anterior Chamber Depth
3.00mmMean loss
>3.00-3.50mm(∆ Mean loss as
compared to ACD 3.00mm)
>3.50mm(∆ Mean loss
as compared to ACD
3.00mm)
3 months 22.1% 19.3%(2.8% less)
16.2% (5.9% less)
6 months 26.3% 20% (6.3% less)
18.8% (7.5% less)
12 months 27.0% -25.0% (2.0% less)
22.3% (4.7% less)
24 months 31.7% 26.9%(4.8% less)
24%(7.7% less)
ACD & Corneal Clearance
IMT is designed for a 2mm corneal endothelial clearanceMinimum ACD was ≥2.5mmNo substudies or data presented to establish suitability of minimum ACD for the established minimum clearance
Haptic Placement
N %
Superior Loop Bag 198 96.1
Sulcus 8 3.9
Inferior Loop Bag 201 97.6
Sulcus 5 2.4
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.
PCO Management
YAG capsulotomy can damage the IMT lenses.
Capsulotomy through the
periphery of the telescope » No patient data available
» Rabbit studies performed
Potential Problems with YAG Procedures
Can only be done around the periphery of the IMTIncreases the # of bursts and total amount of energy delivered to the eyeIncreases risk of Retinal DetachmentPosterior movement of the IMT
Clinical Effectiveness
Visual Acuity
Quality of Life
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.
Preop VA Values - IMT
The preoperative Acuity range was 20/80 - 20/800mean preop BCDVA - 20/312mean preop BCNVA
–@ 8 inches - 20/315 –@ 16 inches was 20/262
Implantation profile
115 eyes were implanted with the
2.2X
91 eyes were implanted with the
3.0X
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
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
Reliability of Low Vision Measures - Russell Woods and Jan Lovie-Kitchin
HCVA logMAR
LCVA logMAR
PRC log contrast units
METlog contrast units
Young Normal .07 0.15
Normal Uncorrected
0.17 0.15
Normal Optically degraded
0.17-0.27 0.18-0.34 0.22-0.36
Moderate Ocular Disease
0.09-0.19 0.19 0.39
LV in Laboratory
0.17
LV in Clinic 0.29 0.25 0.38 0.38
BCDVAChange from
Baseline
Moderate Impairment
(20/80 to 20/160)
Severe Impairment(20/161 to
20/400)
Profound Impairment(Worse than
20/400)
n % n % n %
Gain 3 lines 4 23.5% 46 55.4%
36 76.6
%
Gain 2 lines but <3 lines
4 23.5% 13 15.7% 5 10.6%
Gain 1 line but <2 lines
2 11.8% 10 12.0% 4 8.5%
Other 7 41.2% 14 16.9% 2 4.3%
Gain 2 lines 8 47.1% 59 71.1% 41 87.2%
N 17 83 47
Not reported/IMT removal
0 1 0
Total 17 84 47
Predicted EffectivenessDistance Visual Acuity
IMT Model Mean Preop
BCDVA
Predicted Postop BCDVA
24 Months Postop
3X (2.7X)
20/312 ~20/115(~3 line
improvement)
Mean
BCDVA
20/1502.2X 20/312 ~20/142
(~3 line improvement
)
Predicted EffectivenessNear Visual Acuity
Near Distance
Mean Preop BCNVA
Predicted Postop BCDVA
Mean BCNVA @
24 Months Postop
8 inches 20/315 ~20/105(~3 line
improvement)20/190.2
16 inches 20/262 ~20/87(~3 line
improvement)20/157.6
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
Safety & Effectiveness
Vision Rehabilitation
• Functional Vision
• Orientation & Mobility
• Reading
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.
VFQ-25
PMA reports mean scores and mean changes
FDA requested a frequency analysis for each rating within each category.
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.
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.
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.
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
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.
Adverse events - Falls
8 non-ocular adverse events 8 non-ocular adverse events occurred during this trialoccurred during this trial
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
Central & Peripheral Vision
IMT implanted eyes – CentralFellow eye – Peripheral
No direct performance measures for shifting binocular suppression from one eye to the other.
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
Normal Monocular Field (OD)
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Normal Monocular Field (OS)
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Normal Binocular Field
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Binocular Field for Macular Degeneration Patients
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
SC
Subjective Field of IMT Eye
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
SC
Objective Field of IMT Eye
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Monocular Field - Fellow Eye
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
SC
Objective IMT Binocular Field
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
IMT Objective Binocular Field Fellow Eye Overlap Suppressed
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Motion Discrepancies Magnified/ Unmagnified Fields
Object motionHead motionConsensual eye movementsMotion through the environment
No symptoms were reported for IMT subjects.
Suggests suppression – the IMT image, or – the entire fellow eye image.
IMT Binocular Field with Entire Fellow Eye Suppressed
Inferior
Superior
Left Right
10°
20°
30°
40°
50°
60°
70°
80°
90°
Risks vs. Benefits
The discussion of this device warrants careful
consideration of the reported improvements in visual
acuity with respect to the postoperative risks of ECD
loss, potential perceptual adjustment problems and
unknown problems with examination and treatment of
an IMT implanted eye. .