Enhanced optical coherence tomography imaging by multiple scan averaging

Abstract

Aims: To describe a method for computerised alignment and averaging of sequences in optical coherence tomography (OCT) B-scans and to present selected clinical observations based on the resulting improvement in retinal imaging. Methods: A methodological study and retrospective investigation of selected cases. Five human subjects were included, one healthy subject, two patients with central serous chorioretinopathy, one patient with branch retinal vein occlusion, and one patient with cilioretinal artery pseudo-occlusion. Based on computerised alignment of sets of B-scans obtained at identical retinal locations, average OCT images were produced and displayed in false colour or grayscale. These enhanced tomograms were compared with other morphological and functional characteristics. Results: Improved retinal imaging enabled assignment of the OCT image to retinal anatomy particularly at the outer layer of the photoreceptors and the retinal pigment epithelium, both in the healthy eye and in pathology. Identification of both post-oedematous structural disorganisation as well as post-ischaemic attenuation of the inner retina was superior to standard OCT images. Conclusions: Averaging of multiple OCT B-scans enhances the quality of retinal imaging sufficiently to reveal new details of retinal pathophysiology. Using the technique on OCT3 scans enables visualisation of details comparable with the results obtained using ultra high resolution OCT. F irst generation clinical instrumentation for optical coherence tomography (OCT1 and OCT2) enables reliable demonstration of changes in overall retinal thickness, detection of fluid in and behind the neurosensory retina, and, to some extent, identification of the retinal nerve fibre and photoreceptor layers. The intervening layers of the neurosensory retina are only vaguely discernible and, in spite of the improved resolution of the OCT3, the relation between histology and OCT has not been fully elucidated.Further improvements are possible with ultra high resolution instruments based on titanium sapphire lasers; however, this instrument is yet not commercially available.

Comparison of retinal thickness by Fourier-domain optical coherence tomography and OCT retinal image analysis software segmentation analysis derived from Stratus optical coherence tomography images

“…18 It is worth mentioning that the StratusOCT system images the outer retinal layers (RPE-photoreceptor complex) as two hyperreflective bands: (i) the photoreceptor IS and (ii) the RPE. 19,20 The segmentation software of the StratusOCT system uses the anterior border of the first or innermost hyperreflective band as the border of the outer retina for calculating total RT. 21 OCTRIMA calculates total RT as the distance between the vitreoretinal interface (ILM) and the anterior boundary of the second hyperreflective band corresponding to the OS/RPE junction.…”

Evaluation of choroidal thickness using enhanced depth imaging by spectral-domain optical coherence tomography in patients with pseudoexfoliation syndrome

“…In the enhanced depth imaging technique (EDI), scan acquisition of the choroidal-scleral boundary is set up adjacent to zero delay, where the sensitivity in SD-OCT images is highest. Thus, it has become possible to evaluate ocular tissues located at deeper levels than that of the retina, which could not be evaluated with time domain OCT. 6,7 There are several studies related to both ocular and choroidal blood flow in PEX syndrome. [3][4][5]8,9 However, there have not been any reports to investigate choroidal thickness in patients with PEX syndrome.…”

Evaluation of choroidal thickness using spectral-domain optical coherence tomography in migraine patients during acute migraine attacks: a comparative study

“…7,8 New-generation spectral domain OCT devices with enhanced scanning speed provide the opportunity to achieve high-resolution images and more accurate measurements. Thus, it has become possible to evaluate ocular tissues located at deeper levels than that of the retina, which was not possible with time domain OCT. 7,9,10 In this study, we aimed to evaluate the choroidal thickness of migraine patients during acute migraine attacks and compare them with that of healthy controls.…”