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Rufino Silva, Ruth Hogg, George Murphy, Giovanni Staurenghi, Chiara Rosina, Ana Rita Santos, Usha Chakravarthy; Drusen Detection on Multimodal Imaging- Early Markers Observational Study. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4149. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To report on the relationships of drusen base diameter measured on optical coherence tomography (OCT) and size and appearance graded on colour images. To cross tabulate drusen detectability between OCT, red free (RF), colour and autofluorescence (AF).
Study sample: 105 patients (53 males, 52 females) with unilateral advanced AMD from 3 Centres (Milan, Coimbra, Belfast) age 52-93 years followed for a minimum of 12 months. The study eye comprised of the eye without advanced disease. Colour images were captured on the Topcon 50X fundus camera, red free, AF and OCT on the Heidelberg spectralis using standardised protocols. A single OCT line scan from each patient at each visit was selected from the 361 visits on record. From each scan the base diameter of up to 10 visible drusen was measured yielding 801 measurements. The colour, RF and AF images from each visit were graded as present or absent for the corresponding drusen. If present on colour the size of the druse was estimated as < 63µm, 63 to 124 µm, 125 to 249 µm and > 250 µm. Cross tabulation was undertaken to explore the relationships.
Of the drusen detected on OCT 75% were also seen on colour, 58% on RF and 52% on AF With increasing drusen size on colour grading the mean and SD of drusen base diameter on OCT showed a corresponding increase. The OCT width for the smallest size of drusen of < 63 on colour was 117 (SD 71) for drusen 63 to 124, was 156 (SD 89), for drusen between 125 and 249, was 227 (SD 125) and for drusen > 250 was 296 (SD 125).
Colour grading of drusen showed correlations with drusen base diameter obtained by OCT grading. For each category of size on colour grading, the drusen base diameter on OCT was considerably larger. This suggests that drusen diameter assessed on colour is an underestimate of true size. RF and AF detected fewer drusen than colour images.
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