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
The rationale of electrophysiology testing is to provide objective evidence of function at the different levels of the visual system, thus enabling accurate localisation and characterisation of dysfunction in the vast majority of patients. The three main arms of electrophysiological testing are the:
The ERG records the action potential produced by the retina when it is stimulated by light of adequate intensity. In particular, it assesses the photoreceptor and inner nuclear layers of the retina.
There are four types of waveforms:
The EOG is a measure of the function of the retinal pigment epithelium (RPE) and the interaction between the RPE and the (rod) photoreceptors. It achieves this by calculating the standing potential between the electrically positive cornea and the electrically negative posterior eye. Electrodes are placed at the medial and lateral canthi and the patient is asked to look from side to side in dark then light adaptation. The EOG is quantified by calculating the size of the light peak in relation to the dark trough as a percentage, known as the Arden index. The Arden index is typically over 175% but can be abnormally low in conditions like Best Vitelliform dystrophy.
All rights reserved. No part of this publication which includes all images and diagrams may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the authors, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law.
Vitreoretinal Surgery Online
This open-source textbook provides step-by-step instructions for the full spectrum of vitreoretinal surgical procedures. An international collaboration from over 90 authors worldwide, this text is rich in high quality videos and illustrations.