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Monica Clemo, Dawn A Sim, Daren Hanumunthadu, Praveen J Patel; In Vivo, Non-invasive Visualisation of Perifoveal Capillaries Using Multiwavelength Scanning Laser Imaging. Invest. Ophthalmol. Vis. Sci. 2014;55(13):202. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a standard operating procedure for the purpose of visualising the perifoveal capillary network, using multiwavelength scanning laser imaging (MultiColor Imaging module; Heidelberg UK)
An image capture protocol was designed to capture normative data sets using multiwavelength imaging with the Heidelberg Multicolor module (MCM). The protocol consisted of 3 images at 30° 1 x image using the infrared laser to focus, 1 x image using the blue and 1 x image using the MCM (green) repeated at 20 and 15°. The capture resolution was set at high speed (768 x 768 pixels) and the average real time image rate at 100 ART. Normative data consisting of six subjects was then evaluated for variation in blood vessel delineation between selected focus with varying laser wavelengths of infrared 815nm, blue 486nm and green 518nm. The software used was HEYEX version 1.7.1, Photoshop CS6 was used to trace the blood vessels to distinguish differences in blood vessel delineation and inversion of the images to enhance the visualisation of the deep capillary plexi
Imaging was captured of 6 normal subjects with a mean age of 25 years, 4 females and 2 males. Visualisation of the superficial capillary plexus was best achieved when the focus was applied with the blue laser wavelength, however visualising the deep capillary plexus was best achieved when focus was applied using the MCM mode (Fig.1). Further clarity of the deep capillary plexi could be achieved by inverting the color output (Fig.2a) and the green channel output of the multicolour MCM fundus image (Fig.2b) Fig.1 Left: Multicolor mode fundus image of the superfical capillary plexus when focus is applied using the blue laser Right: Multicolor mode fundus image of the deep capillary plexus when focus is applied using the green laser Fig.2 Left to right 30° inverted MCM module blue channel fundus image demonstrating the separation of the superficial capillary plexus 30° inverted MCM color fundus image combined demonstrating improved clarity of the deep capillary plexus 15° blue channel (no inversion) showing the superficial capillary plexus 15° green channel with inversion showing the deep capillary plexus
We describe a standard operating procedure for multiwavelength imaging (using the Heidelberg MCM) to visualise the superficial and deep peri-foveal capilary plexi without the need for intravenous contrast agents.
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