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J. S. Gandhi, C. Campa, Y. Zheng, D. Sanusi, D. M. Broadbent, S. P. Harding; Optimisation of a Fluorescein Angiography Protocol for Improved Clinical Assessment of Capillary Perfusion in the Diabetic Macula. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4695.
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Our aim was to modify a fluorescein angiography (FA) protocol for improved clinical assessment of the capillary network in diabetic retinopathy.
Two consecutive age-matched groups of patients were examined. Imaging was performed using the Heidelberg HRA2 system, using ETDRS fields.Group 1 underwent imaging with a Standard Protocol (SP). A 6 month development period followed and explored variables such as concentration of dye, speed of injection, sequence of mono- and stereo imaging of FA phases, and timing of switch to fellow eye. Group 2 were examined with the resulting Optimised Protocol (OP).Post-acquisition grading of images was undertaken by two retina specialists. FA quality was defined according to ability to visualise foveal avascular zone (FAZ) outline, perifoveal capillary non-perfusion zones, foveal microaneurysmal leakage, accumulation of dye at the foveal centre, and micro- and macrocystoid oedema. Visualisation of the FAZ outline was used to grade the overall quality of the angiogram (Good, Adequate, Borderline): ‘Good’ where 50-100 % of the perifoveal vasculature was visualised, ‘Adequate’ for 25-49 %, and ‘Borderline’ for 0-24 %.
The OP used 3 ml of 25 % fluorescein versus 5 ml of 20 % in the SP, with injection performed over 2 seconds rather than 5 seconds. Mono-F2 images in the transit phase were taken every 1 sec instead of every 3 sec. Compared to a switch at 50 sec in the SP, a move to the fellow eye was made once a clear image of perifoveal vasculature was obtained. A typical transit phase sequence consisted of study eye 0-30 sec and fellow eye 30-50 sec. The OP also included mid-phase F2 stereo (1-5 min), 7-field stereo of study and fellow eye (1.5-2.5 min), and late phase stereos of F1 and F2 at 5 and 10 min, in comparison to only F2 in the SP.In the study eye, the SP produced Good/Adequate images in 5/19 (26%) compared to 14/22 (64%) in the OP (p<0.05).For the fellow eye, SP produced 0/19 (0%) Good/Adequate images compared to 4/22 (18%) eyes in the OP.
Careful attention to the FA protocol optimises assessment of the key features of diabetic maculopathy aiding clinical management in a common but complex group of patients.
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