Imaging protocol and analysis
streaks inferior, swelling, haemorrhages
POSTERIOR, OPTIC NERVE, HAEMORRHAGES
The Heidelberg Spectralis spectral-domain OCT device (Heidelberg Engineering, Heidelberg, Germany) was used by masked technicians. Posterior Pole scan, 30° × 25°, 240 Sects. (30 μm), high speed, ART 20 and a Peri-papillary Pre-set RNFL scan ART 100 were acquired preoperatively and at each FU. In addition, a 5° × 15°, 49 Sects. (30 μm), high speed, ART 20 was performed preoperatively and a separate high-definition infrared (IR) image with high ART (25) preoperatively and the 3-week visit. Images were exported anonymised for masked grading at a certified image grading centre (NetwORC UK, Central Angiographic Resource Facility, Queen’s University, Belfast, Northern Ireland).The 3-week IR images were graded for the number of haemorrhages and dark RNFL lesions with corresponding RNFL thickening on SD-OCT representing SANFL lesions (Fig. Three weeks postoperative infrared image illustrating a closed hole with 3 areas of subacute nerve fibre layer swelling shown as dark streaks inferior to the fovea (marked with white arrows)Using the Heidelberg auto-segmentation algorithm the inner retinal thickness (IRT), as a combined value of the RNFL, ganglion cell layer and inner plexiform layer thicknesses, was evaluated using the 1, 3, 6 mm ETDRS grid as well as the custom 8 × 8 grid centred on the fovea. The RNFL thickness was measured using the automated Heidelberg RNFL thickness algorithm in 6 peripapillary zones. All automatic segmentations were manually checked and adjusted in case of gross segmentation errors by masked graders.Finally, various parameters describing a dissociated optic nerve fibre layer (DONFL) appearance were calculated using the en-face OCT from the 6-month scans. An axial slab encompassing the inner surface of the ILM to the outer border of the RNFL using the automated segmentation algorithm was selected (Fig. Composite diagram showing methodology for DONFL quantification. 