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E.R. Drudy, S.A. Newman; Reproducibility of RAREbit Perimetry in Normal Subjects . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4320.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the reproducibility of RAREbit perimetry Methods: Individuals without known ophthalmic pathology were recruited. Best corrected distance visual acuity (Va) was measured, and the RAREbit visual field (VF) test was taken on 2 separate occasions. Values for mean test time (TT), mean reaction time (MRT), mean hit rate (MHR), average # of hit rates (HR) <90, and MHR <90 were compared between OD and OS for each test and between the same eye for the 1st and 2nd test. Results: Twelve participants (7 men, 5 women) ages 28 to 55 (average: 33.8, SD±9.4) participated. Va was 20/20 in 62.5% and 20/15 in 37.5%. The mean number of points tested in each eye was 167 (SD±4.67). Mean TT for each eye was 5.48min, SD±0.53. The mean difference in TT was less for the 2nd eye in both test 1 (–0.22min, SD±0.46) and test 2 (–0.05min, SD±0.43), and was shorter for each eye during the 2nd test (OD: –0.45min, SD±0.60; OS: –0.15min, SD±0.45). Average MRT was 0.78sec, SD±0.15. The average difference in MRT for the 2nd eye increased in both test 1 (0.15sec, SD±0.15) and test 2 (0.02sec, SD±0.17), but for the same eye was shorter in the 2nd test (OD: –0.038sec, SD±0.09; OS: –0.029sec, SD±0.20). Average MHR for all tests was 92.4%, SD±9.43. The average MHR in the 2nd test improved by 6.67% (SD±7.58) OD and 2.67% (SD±4.19) OS. The mean # of HR<90 was 5.40 (SD±6.95). The # of HR<90 improved for the 2nd eye in the 1st test (–0.25, SD±4.0), but not the 2nd test(1.0, SD±3.94). The average # of HR<90 improved for each eye on the 2nd test (OD: –3.67, SD±4.87; OS: –1.25, SD±2.67). The average difference in MHR for the group of HR <90 increased for the 2nd eye in both tests (Test1: 13.67, SD±41.23; Test 2: 8.58, SD±39.20), as well as for OD (4.42, SD±32.17). OS actually had a decrease in MHR<90 (–1.17, SD±34.09). Conclusions: By using high intensity, point sources of light, RAREbit perimetry attempts to elucidate subtler pathology than can be detected by standard VF tests. However, the greater sensitivity creates a more challenging test with a notable learning curve: TTs consistently improved with experience and overall MHR increased, whereas the # of HR<90 decreased for the latter test. This moderate fluctuation in results is likely due at least in part to a learning effect. Therefore, cautious interpretation of initial results of the RAREbit VF test and repeat testing are recommended. In addition, because of the finer stimuli and the need for tracking ability, there seems to be a fatiguing effect––MRT slowed for the 2nd eye in each test. This, also, should be weighed against the learning effect in deciding which eye to test first, particularly in subjects with expected pathology.
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