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Tunde Peto, Stela Vujosevic, Ferenc B Sallo, Daniela Florea, Irene Leung, Traci E Clemons, Emily Y Chew, Alan C Bird, MacTel Study Group; Comparison of two microperimetry tests in a clincial trial for Macular Telangiectasia Type 2. Invest. Ophthalmol. Vis. Sci. 2014;55(13):674.
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© ARVO (1962-2015); The Authors (2016-present)
Macular Telangiectasia Type 2 (MacTel) causes significant retinal sensitivity loss which can be mapped by microperimetry (MP). Seven patients of the CNTF Phase 2a trial performed two different types of microperimetry, using NIDEK MP1 and CenterVue MAIA at baseline, 1 week, then 1, 6, 12, 18 and 24 months.
Fourteen eyes of 7 patients were tested using the two microperimeters, except for one subject’s 24 months’ follow up that is missing due to illness. All tests were performed under mesopic conditions using predetermined testing grids. All data for both tests were sent to the Moorfields Reading Centre for analysis. Test duration, fixation and scotoma characteristics were analyzed and compared between the two tests at all available relevant visits. Due to the wider dynamic range of the MAIA, only patterns of abnormality of retinal thresholds could be analyzed.
Five participants were female and the median age was 54 years. All test results were good enough quality for analysis. The average test duration was 11.8 (95% CI: 11.1-12.4 minutes) on MAIA and 16.2 (95% CI: 14.0-18.4 minutes) on MP1 at baseline/screening; 12.1 (95% CI: 10.9-13.2 minutes) on MAIA and 17.5 (13.8-21.2 minutes) on MP1 at 1 year; and 12.5 (95% CI: 10.5-14.5 minutes) on MAIA and 13.1 (95% CI: 9.3-16.9 minutes) on MP1 at month 24. At baseline 91% of eyes had stable and 9% had relatively unstable/unstable fixation on MP1 and this was not significantly different on MAIA (McNemar’s p-value = 0.32). At 1 year 64% and of eyes had stable and 36% had relatively unstable fixation on MP1. Similar results were found for MAIA (McNemar’s p-value = 0.18). The mean number of absolute scotomas at baseline, 1 year and 2 years were higher on MP1 (2.4±3.9 vs 0.7±1.4, p=0.004; 2.4±3.9 vs 1.1±2.1, p=0.09; and 2.7±3.8 vs 0.5±0.9 p=0.06). However, 50%, 50% and 42% of eyes at baseline, 1 and 2 years, respectively, with absolute scotomas on MP1 had relative scotomas on MAIA. On both machines, absolute and relative scotomas were predominantly located temporal to the fovea. Feedback from operators and patients favoured MAIA due to ease of use.
Both machines provide reliable and clinically relevant data on patients with MacTel in the context of a clinical trial. Further data are needed to ensure which grid pattern and which machine are the best to use in this disease.
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