OSLI Retina

December 2019

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802 Ophthalmic Surgery, Lasers & Imaging Retina | Healio.com/OSLIRetina OCTA: A Practical Method of Image Averaging Using Adobe Photoshop Software Mirriam Mikhail, MD(C); Shangjun Jiang, MD; Paul Hahn, MD, PhD; Anton Orlin, MD; Rajesh C. Rao, MD; Netan Choudhry, MD, FRCSC BACKGROUND AND OBJECTIVE: To describe a meth- od for averaging ocular coherence tomography an- giography (OCTA) images using a commercially available photo editing software: Adobe Photoshop CC 2017. PATIENTS AND METHODS: This single-center study assessed the feasibility of using Adobe Photoshop as an OCTA image averaging tool. Three 3.0 mm × 3.0 mm OCTA images from each eye were obtained us- ing commercially available OCTA devices. Captured OCTA images were exported in high-resolution TIFF format, imported as an image stack, aligned using an automated function, and averaged by creating a Smart Object using Photoshop CC 2017 software. In conjunction with qualitative assessment, the main outcome of the study was image grader preferences with respect to clarity of the foveal avascular zone (FAZ), blood vessel delineation, and the ability to identify abnormal vasculature. RESULTS: After removing OCTA scans with signifi- cant image distortion, 25 sets of images were in- cluded in the analysis. Adobe Photoshop CC 2017 successfully aligned and averaged all images of the superficial and deep retinal plexuses that con- tained a minimum 40% overlap. Three indepen- dent retinal specialists found the averaged images to be slightly or definitely preferable to the original 87%, 89%, and 69% of the time with respect to clarity of the FAZ, clarity of blood vessel delinea- tion, and the ability to identify abnormal vascula- ture, respectively. CONCLUSIONS: Adobe Photoshop CC 2017 is an excellent tool for image averaging, producing high- quality resulting OCTA images. As an easily acces- sible software, Photoshop has the potential for use in a diversity of pathological conditions. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:802-807.] INTRODUCTION The advent of optical coherence tomography angi- ography (OCTA) has provided a noninvasive imaging modality used to visualize retinal vasculature in de- tail. The visualization of both structural and vascular information in vivo potentiates the clinical evaluation of retinal conditions such as diabetic retinopathy, wet age-related macular degeneration, and retinal vascu- lar occlusions. 1-4 Image averaging, a technique widely used in OCT, has been shown to improve retinal vi- sualization, revealing new pathophysiology details. 5 Image averaging has been utilized in OCTA to provide higher-resolution images bearing a greater signal-to- noise ratio. 6 Motion-correction software available on some OCTA devices further improves image quality through volumetric registration, reducing the level of artifact. 7 OCTA image averaging was first conducted using ImageJ (NIH, Bethesda, MD) and was used by Mo et al. to obtain quantitative metrics such as capil- lary density, demonstrating significant enhancement of image quality, and remote procedure call param- eters. 8 Furthermore, multiple en face OCTA image averaging has been shown to improve the visualiza- tion of the choriocapillaris by reducing image granu- larity. 9 This technique holds promise for improving the morphological visualization of retinal structures on OCTA. Macular telangiectasia (MacTel) type 2 is a retinal vasculature disease characterized by abnormalities in From Faculty of Medicine, University of Toronto, Toronto, Ontario (MM, SJ); New Jersey Retina, Teaneck, New Jersey (PH); Weill Cornell Medical Col- lege, New York City (AO); University of Michigan W.K. Kellogg Eye Centre, Ann Arbor, Michigan (RCR); Vitreous Retina Macula Specialists of Toronto, Toronto, Ontario (NC); and the Department of Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario (NC). Originally submitted September 30, 2018. Revision received March 18, 2019. Accepted for publication June 13, 2019. Dr. Choudhry is a consultant for Topcon and receives research support from Zeiss and Optovue. None of the aforementioned companies had a role in the study design, collection, analysis, or interpretation of data in this report. The remaining authors report no relevant financial disclosures. Address correspondence to Netan Choudhry, MD, FRCSC, Vitreous Retina Macula Specialists of Toronto, 3280 Bloor St. West, Suite 310, Etobicoke, ON M8X 2X3, Toronto; email: netan.choudhry@vrmto.com. doi: 10.3928/23258160-20191119-09 ■ B R I E F R E P O R T ■

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