Emmanouil Tsamis

Swept-Source Optical Coherence Tomography Angio™ (Topcon Corp, Japan): Technology Review.

Optical coherence tomography (OCT) angiography (OCTA) is a novel, noninvasive, three-dimensional imaging technique that allows for the visualization of intravascular flow in the microvasculature. Swept-source OCT technology utilizes longer-wavelength infrared light than conventional spectral-domain OCT. This enables improved penetration into tissue and imaging through optical opacities and is invisible to the subject. Topcon has recently developed an innovative OCTA algorithm, OCTARA (OCTA Ratio Analysis), which benefits from being paired with swept-source OCT. OCTARA aims to provide improved detection sensitivity of low blood flow and reduced motion artifacts without compromising axial resolution. In this chapter, we describe the implementation of OCTARA with swept-source OCT technology, the technical specifications of acquisition (e.g. the number of scans, area of examination field, etc.) along with the algorithms function and principles for analysis of B-scan data to achieve angiographic visualization. Examples of OCTA scans performed using the OCTARA algorithm and a comparison of these scans with images obtained using other technologies are also presented.

New Findings in Diabetic Maculopathy and Proliferative Disease by Swept-Source Optical Coherence Tomography Angiography.

PURPOSE To describe the optical coherence tomography (OCT) angiography (OCTA) features of diabetic retinopathy. METHODS Retrospective serial case reports were examined of patients who underwent routine clinical examination and OCTA with both DRI OCT Atlantis prototype and Triton Swept-Source OCT of the posterior pole and mid-periphery. When considered necessary, fluorescein fundus angiography (FFA) with OPTOS California wide-field imaging was performed. The findings were compared with the current literature. RESULTS Forty-three consecutive patients (86 eyes) were evaluated. Fourteen of these patients (28 eyes) underwent an additional FFA examination due to advanced retinopathy signs, such as diabetic macular edema, ischemia or neovascularization (NV). OCTA was able to detect the microvascular lesions observed on color fundus images in the whole sample. Thirty-six of the 86 eyes showed foveal avascular zone enlargement on OCTA. Microvascular lesions, diabetic macular edema, and NV of the optic disc observed on FFA were also detected on OCTA in all cases (28/28 eyes). Features of NV elsewhere were detected on FFA in 16/28 eyes. Ten of the 16 eyes had signs of NV within the 100 central degrees, and OCTA was able to detect these signs in 9 of the eyes. CONCLUSION OCTA is an effective noninvasive imaging technique that can provide additional information regarding the localization and morphology of vascular lesions in all cases of NV of the optic disc and in more than half of cases of NV elsewhere, suggesting that it is a noninferior technique for the study of posterior pole alterations compared with FFA, which remains the gold standard and is fundamental for the study of the retinal periphery.

Swept-Source Optical Coherence Tomography Angiography of Paediatric Macular Diseases

PURPOSE To describe the optical coherence tomography (OCT) angiography (OCTA) features of paediatric macular pathologies. METHODS Retrospective serial case reports of patients who underwent routine clinical examination and OCTA of the posterior pole using both a DRI OCT Atlantis prototype and Triton Swept-Source OCT. When considered necessary, imaging was performed using Optos wide-field imaging or another non-invasive imaging system. The findings were compared with the current literature. RESULTS Three cases with X-linked retinoschisis, 2 with epiretinal membrane, 1 with Best disease and 2 with Coats disease are fully illustrated. CONCLUSION OCTA is an effective, non-invasive imaging technique that can offer additional information regarding the morphologies and vascular characteristics of macular lesions in paediatric ophthalmology. Because of the rarity and characteristics of many paediatric macular pathologies, further multi-centric research is required with regard to the utilisation and features of OCTA imaging.

The effect of bevacizumab before vitrectomy for diabetic tractional retinal detachment demonstrated on optical coherence tomography angiography

Purpose To demonstrate the effect of intravitreal bevacizumab (IVB) on the size and vascularity of the fibro-vascular complex with the optical coherence tomography angiography (OCTA) before pars plana vitrectomy (PPV). Methods Observational case series of three eyes with active diabetic fibro-vascular complex and tractional retinal detachment (TRD) who underwent IVB (1.25 mg/0.05 ml) two days before proceeding to PPV. OCTA was carried out prior to IVB, two days after IVB and six weeks after PPV. Results OCTA showed a reduction in the size and calibre of the diabetic fibro-vascular complex two days after IVB in all the cases. Consequently, there was less traumatic dissection of the fibro-vascular membranes during PPV and thus reduced chances of intraoperative and postoperative vitreous cavity bleeding. One case showed mild hemorrhage in the posterior vitreous on the second day post-injection which implies the increased traction caused by IVB. Conclusions In this case series, we have used OCTA to demonstrate how IVB is highly effective in reducing the vascularity of diabetic fibro-vascular membranes. This finding also suggests that the use of IVB before PPV in the management of diabetic TRD could also be much shorter than the advocated standard practice of one week in most institutions.