9.1 Corneal Topography and Tomography
9.2 Confocal Microscopy
9.3 Optical Coherence Tomography - Macula
9.4 Optical Coherence Tomography Angiography (OCT-A)
9.5 Optical Coherence Tomography - Glaucoma
9.6 Optical Coherence Tomography – Anterior Segment
9.7 Fundus Autofluorescence Imaging
9.8 Fundus Angiography - Fluorescein
9.9 Fundus Angiography - Indocyanine Green
9.10 B-scan Ultrasonography & UBM
9.12 Automated Visual Fields
Optical Coherence Tomography (OCT) is a crucial tool for diagnosing and monitoring retinal and glaucomatous disease. It produces cross-sectional images by studying interference patterns formed between infrared light reflected off the retina and a reference beam. Candidates should have an understanding of normal and pathological OCT scans. It is important to appreciate that OCT layers represent reflective interfaces, not true anatomy. High definition spectral domain OCT allows for greater precision in identifying these interfaces than time domain OCT. The addition of colour is artificially introduced and does not add further information than grey-scale scans.
Hard Exudate and Retinal Oedema
The hyperreflective dots in the outer retina are hard exudate, whereas the hyporeflective expansion of the outer retinal layers represents more diffuse oedema. Hard exudates usually develop in the setting of chronic retinal oedema. These findings are non-specific.
Multiple raster images are automatically acquired together and stacked to give information about a volume of retina (the “cube”). This is then displayed as a heat map showing retinal thickness (top left panel). Software-generated segmentation lines for the individual raster slices are shown in the bottom left panel. Software registration of the acquisition allows for the same volume of retina to be imaged at different points in time and compared (as shown in the right panel of three scans of time point A, time point B, and change map A – B).
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