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Giuliana Silvestri, Geeta Menon, IV, Emma Hollick, Carmel McAfee, Hannah Dunbar, Liz Pearce, Mark R. Wilkins; Visual and Quality of Life Outcomes from the IMT-UK Study. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4409.
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The Implantable Miniature Telescope allows a 3X retinal image enlargement for distance, intermediate, and near vision (with appropriate spectacle correction) for end-stage AMD patients. The device has been tested for safety and efficacy in a US pivotal trial and has received both CE and FDA approval. The results of the US trial (n=217) showed 90% (vs. protocol requirement of 50%) achieved the primary endpoint of 2 lines improvement in distance or near best-corrected visual acuity (BCDVA or BCNVA). The aim of the IMT-UK study was to evaluate the same endpoint, and mechanisms of patient selection and rehabilitation in the UK setting. Additionally, visual and psychological parameters which are important in patient selection were considered, and investigation of whether implanting the "better" seeing eye would be acceptable and/or advantageous. The better eye was always implanted in this study.
The study was a prospective, open-label multi-center study. The target number of eyes was up to 75 consecutive eyes with follow-up for 12 months. The primary end point was ≥ 2 line improvement in either near or distant BCVA in 50% of implanted eyes at 12 months post-implantation. A secondary outcome measured was improvement in quality of life assessed using the NEI VFQ-25.
Eighteen patients were implanted with the telescope prosthesis in 3 sites. The final number of patients implanted fell short of the recruitment target (24%) despite usual efforts in recruitment (non-advertising). The results at 12 months were as follows: 72% of patients improved by > 2 lines of BCDVA or BCNVA, thus meeting the established endpoint. The average improvement in BCDVA at 12 months follow-up was 2.8 lines; the average improvement for BCNVA at 12 months was 2.1 lines. The average Quality of Life score at 12 months was 0.56 (range: +29 to -29).Eleven patients were available post-implantation for interview (>12 months). All 11 reported they would recommend a close friend or relative undergo the procedure, 8 of the respondents indicated they would undergo the procedure again.
In summary, the study achieved the primary visual end points. Mean quality of life scores were less robust than in the US trial in this smaller patient population. Again, this may be related to the small sample size and the reason for difference is thus unknown (18 UK patients vs 206 US patients).Psychological parameters which may be important in the selection of patients for this procedure is complex and analysis are ongoing, however implanting the better-seeing eye appears to be acceptable in this limited sample based on patient interview response. The post-operative rehabilitation schedule over a 6-month period was appropriate for most patients.
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