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Jae Y Ku, Simon P Harding, Deborah M Broadbent, Amira Stylianides, Ticiana Criddle, Paul C Knox; Performance of the handheld Radial Shape Discrimination test in Diabetic Macular Oedema suspects. Invest. Ophthalmol. Vis. Sci. 2017;58(8):927.
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© ARVO (1962-2015); The Authors (2016-present)
The UK National Diabetic Eye Screening Programme (NDESP) refers large numbers of people with suspected Diabetic Macular Oedema (DMO), based on non-stereoscopic photographs, to hospital eye services. Few of them have disease requiring treatment. Could the handheld Radial Shape Discrimination test (hRSD; Wang et al, IOVS, 2013;54:5497) be used to reduce this high referral rate? In a prospective observational study, we investigated the performance of the hRSD test in DMO suspects.
Ninety-eight patients (57 male; age mean±SD: 54.2±16.5y; range 20-86y) referred from screening to a hospital diabetic eye clinic with screen positive maculopathy (defined as M1 by the NDESP screening guidelines), completed near and distance visual acuity (VA), a four-alternative-forced-choice hRSD test (presented on an Apple iPod Touch) and a four-question usability survey. Dilated fundoscopy and spectral domain OCT (Heidelberg) of the macula were performed and eyes were regraded according to NDESP guidelines. OCT retinal thickness and volume were analysed for the 9 ETDRS subfields. Eyes with confounding ocular pathologies were excluded.
Randomly selecting one eye per patient for analysis, 5% of eyes had DMO based on the presence of fluid in the central subfield with central subfield thickness (CST) ≥318µm. Mean (±SD) near and distance VA were 0.16±0.24 logMAR and 0.04±0.17 logMAR respectively. hRSD threshold was -0.61±0.21 logMAR, significantly worse than normal (−0.80±0.12 logMAR, t=-8.2,p=<0.001; Ku et al, Peer J, 2016; 4:e2650). Mean central foveal thickness and CST were 237.97±32.52µm and 284.67±31.44µm respectively. hRSD thresholds significantly correlated with near (r=0.50, p<0.001) and distance (r=0.47, p<0.001) VA. Correlations between other ETDRS subfield thicknesses and hRSD thresholds were not statistically significant. For eyes with the same clinical retinopathy grade, there was no statistical difference in the hRSD thresholds for those graded with and without maculopathy. No eyes received Anti-VEGF therapy or macular laser. The usability survey results indicated positive patient responses to the hRSD test.
While hRSD threshold in DMO suspects differed statistically from normative values, further data from eyes with confirmed DMO will be required to draw conclusions regarding the diagnostic utility of the hRSD test in detecting DMO, and its potential role in screening..
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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