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N. Ianopol; The Mathematical Assessment of the Ocular Fundus Lesions in Fluorescein Angiography by Using SITE-Application. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4250. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the steps of SITE-Application (SITE-App) and its advantages in the mathematical assessment of the ocular fundus lesions (OFL) in fluorescein angiography (FA).
SITE-App is an algorithm that allows the calculation in pixels of the relative area (RA) of the ocular fundus lesions revealed by the FA and red free images (RFI). After establishing of the type of the interest OFL, "white" (e.g. neovascularization) or "black" (e.g. subretinal hemorrhage), the best angiographic image (recorded by any type of digital device for FA) is opened in Adobe Photoshop. The color curves are modified by specifying the maximum level for "black" and "white". The contrast of the picture is modified until the lesion is the best visualized. The "Gaussian filter" is applied in order to decrease the aspect of "pixels" at the lesions’ boundaries. The ophthalmologist delimitates the area of interest including the analyzed lesions. A special color range is chosen from the selected zone, at the best fuzziness, until the whole lesion is covered. The lesion is colored in black. The background is eliminated. The extracted lesion is processed in SITE-App that presents the RA in pixels.
The algorithm may be applied for "white" OFL (e.g. neovascularization), for "black" ones (e.g. subretinal hemorrhage) revealed by FA or for "white" OFL (e.g. scars) evident in red free images. The final results are not altered by the possible interpreting errors caused by the examiner or computers. Performing 2 successive applications on the FA and/or RFI, mixed OFL (e.g. neovascularization /scars) can be evaluated and followed up. SITE-App is more accurate than other methods for the evaluation of the OFL in FA (e.g. calculation of the lesions’ largest diameter, or the OFL area presented in mm²) allowing the assessment even for noncompact OFL. Performing SITE-App for the same eye, in different moments, but using the same digital device for FA and the same parameters for exposure of the ocular fundus, the evolution of the OFL as well as the efficacy of different treatments may be accurately followed and assessed. SITE-App allows the assessment even in critical cases such as excentric image due to poor fixation or, blurred AF image due to the opacification of the ocular refractive media (when the measurements of the best corrected visual acuity is not an accurate method to follow up the case).
SITE-App is an accurate and useful method for the interpretation of the OFL in FA, allowing the follow up of the evolution of the disease and the efficacy of different treatments.
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