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Gorka Sesma,1 Tasnim Al Mairi,2 Heba Fareed Khashoggi,1 Shorog Ibrahim AlDhahi,1 Fahad Aljohar,3 Rajiv Khandekar,4 Abdulaziz Awad1 1Pediatric Ophthalmology and Strabismus Division, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia; 2Emergency Department, Almoosa Specialist Hospital, Al Mubarraz, Saudi Arabia; 3Diagnostic and Imaging Department, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia; 4Department of Vision Science, University of British Columbia, Vancouver, CanadaCorrespondence: Gorka Sesma, Pediatric Ophthalmology and Strabismus Division, King Khaled Eye Specialist Hospital, Al Urubah Branche Road, West Building 2nd Floor, Riyadh, 11462, Saudi Arabia, Tel +966 11 4849700, Fax +966 11 4821908, Email gsesma@kkesh.med.saPurpose: Optical coherence tomography angiography (OCTA) noninvasively images retinal microvasculature. Foveal avascular zone (FAZ) biomarkers can act as indicators of various forms of amblyopia, making them valuable tools for clinicians. The purpose of this study was to assess the effect of amblyopia therapy on the FAZ using OCTA to determine FAZ size in children with untreated amblyopia.Patients and Methods: This two-arm cohort study enrolled 23 children with untreated strabismic or anisometropic amblyopia who underwent OCTA between 2021– 2022. Each arm had 23 eyes, with one arm having amblyopic eyes and the other having normal eyes. FAZ area, perimeter, and circularity index were measured before and quarterly during 1 year of occlusion therapy. Differences in avascular zone biomarkers between amblyopic and fellow eyes were compared and linked to demographic and ocular factors.Results: Similar FAZ areas were found in the amblyopic (0.3 mm2) and nonamblyopic eyes (0.28 mm2) (P = 0.83), with no significant change in either group (P = 0.93). Amblyopic eyes showed a larger FAZ perimeter reduction (0.12 mm2) than fellow eyes (0.02 mm2), but the difference was not statistically significant (P = 0.09). The circularity index in amblyopic eyes matched with fellow eyes (0.67 mm2), P = 0.38. Initial visual acuity and strabismus correlated with changes in the follow-up FAZ area.Conclusion: Amblyopia treatment did not significantly alter FAZ area in this cohort. Perimeter variations between amblyopic and fellow eyes require further study. The conclusions were limited by the sample size and lack of randomization.Plain Language Summary: Amblyopia is a common vision problem in children in which one eye does not see the fellow eye. This can occur if the eyes are not lined up right or if their prescriptions are different. Amblyopia is treated by placing a patch over the stronger eye to help the weaker eye better see.Researchers have used a technique called optical coherence tomography angiography (OCTA) to compare the foveal avascular zone (FAZ) before and after treatment in children with amblyopia. The FAZ is a spot on the back of the eye where there are no blood vessels or light-sensitive cells. Changes in the FAZ may indicate the severity of amblyopia.The study included 23 children with untreated amblyopia. Over the course of more than a year, measurements of FAZ area, perimeter, and roundness were taken before and during occlusion therapy. The size of the FAZ was also compared between the eyes with and without amblyopia.At the start of the study and after treatment, there were no significant differences between the FAZs of amblyopic eyes and other eyes. There were some differences in the size of the FAZ between eyes. Changes in the FAZ area were linked to the initial state of vision and misalignment.Overall, this study found that occlusion therapy did not change FAZ area in children with amblyopia. More research is needed to determine why the FAZ perimeter can differ between the eyes. Larger randomized studies would provide more information about how the FAZ changes when treating amblyopia.Keywords: amblyopia, optical coherence tomography angiography, foveal avascular zone, occlusion therapy, biomarkers

Ranjila Shyangbo,1 Priya Bajgai,2 Raju Kaiti,3 Gopal Prasad Pokharel2 1Department of Optometry, National Academy of Medical Sciences (NAMS), Kathmandu, Nepal; 2Department of Ophthalmology, Nepal Eye Hospital, Kathmandu, Nepal; 3Department of Optometry, Nepal Eye Hospital, Kathmandu, NepalCorrespondence: Ranjila Shyangbo, Department of Optometry, National Academy of Medical Sciences (NAMS), Mahaboudha, Kathmandu, 44600, Nepal, Tel +977- 9861499785, Email alijnar@gmail.comPurpose: To establish normative data on morphological characteristics and quantitative parameters of Foveal Avascular Zone (FAZ) as well as their systemic and ocular associations using OCT angiography (OCT-A) in healthy Nepalese subjects.Patients and Methods: A prospective, cross-sectional, population-based study recruiting 210 healthy samples (420 eyes) aged 10 to 70 years was conducted. All the samples underwent detailed comprehensive eye examination followed by Optical Coherence Tomography Angiography (OCTA) and Enhanced Depth Imaging performed in each eye using Spectral Domain Optical Coherence Tomography. Foveal avascular zone area and vessel density in superficial and deep retinal plexus and Sub foveal Choroidal Thickness (SFCT) were evaluated. Ocular and systemic associations of these parameters were also studied in a multivariate analysis utilizing linear regression.Results: The mean superficial and deep FAZ area was 459.96 ± 124.75 μm (95% confidence interval [CI], 443.08– 476.83) and 589.0 ± 141.39 μm (95% CL, 570.77– 609.02), respectively. The vessel density in superficial capillary plexus was 54.03 ± 9.34% (95% CL, 53.98– 54.11) while the vessel density in deep capillary plexus was 25.91 ± 38% (95% CL, 25.85– 25.96). The mean SFCT in this study was 308.89 ± 68.87μm (95% CL, 299.64– 318.14 μm). There was no statistically significant inter-eye difference in the FAZ parameters. Myopic eyes had smaller FAZ, lesser vessel density and thinner SFCT. Association was observed between superficial FAZ area and systolic blood pressure, and deep FAZ area and diastolic blood pressure.Conclusion: This study reports the normative data on FAZ parameters in healthy Nepalese subjects which can serve as references for interpreting these parameters in different retinal-choroidal diseases.Keywords: choroidal thickness, EDI-OCT, foveal avascular zone, healthy eyes, OCT-angiography

Marcus Werner Storch,1 Greta Zinser,1 Peer Lauermann,1 Mohammed Haitham Khattab,1 Anna Nguyen-Höhl,1 Dirk Raddatz,2 Katja Gollisch,2 Josep Callizo,1 Hans Hoerauf,1 Nicolas Feltgen1 1Department of Ophthalmology, University of Göttingen, Göttingen, Niedersachsen, Germany; 2Department of Gastroenterology, Gastrointestinal Oncology and Endocrinology, University of Göttingen, Göttingen, Niedersachsen, GermanyCorrespondence: Marcus Werner Storch, Department of Ophthalmology, University of Göttingen, Robert-Koch-Str. 40, Göttingen, 37075, Germany, Tel +49-551-39-63580, Fax +49-551-39-63582, Email marcus.storch86@googlemail.comPurpose: To correlate functional and morphological parameters with foveal avascular zone’s (FAZ) size in diabetic patients with mild to moderate stage nonproliferative diabetic retinopathy.Methods: Monocentric and prospective study of a consecutive case series of diabetic patients. Medical history, best corrected visual acuity (BCVA), best corrected high/low contrast visual acuity (BChcVA/BClcVA), mean sensitivity (MS) and mean defect (MD) in central visual field testing, and FAZ size in fluorescein-angiography (FAG) were recorded. Macular thickness (central point thickness CPT, central subfield thickness CST) and volume measurements (central subfield volume CSV, total macular volume) were taken from SD-OCT (6x6mm ETDRS-grid). Groups were categorised as presenting FAZ sizes smaller (G1) or larger (G2) than 0.35mm2. Smallest (Q1) and largest quartiles (Q3) were also compared.Results: Thirty-six of 40 patients were included. MS differed significantly between G1 (n = 6) and G2 (n = 30), and BChcVA/BClcVA as well as TMV correlated significantly with FAZ size in correlation analysis. Mean HbA1c tended to be lower in G1 than G2. Patients in G1 were slightly older than in G2. Treatment period with insulin was shorter in G1/Q1 than in G2/Q3. CPT and TMV were lower in G1/Q1 than in G2/Q3. Our analysis of the FAZ in terms of patient age, HbA1c, disease duration and insulin therapy duration revealed no significance. That lack of significance also applies to BCVA, MS, MD, CPT, CST and CSV.Conclusion: As significantly associated, contrast sensitivity, central visual field parameters and potentially retinal thickness or volume seem to be suitable to detect early macular ischaemia. However, we failed to establish any correlation between FAZ and BCVA.Keywords: foveal avascular zone, contrast vision, visual acuity, fluorescein angiography, diabetic retinopathy, ischemia

Janarthanam Jothi Balaji,1 Rajiv Raman,2 Vasudevan Lakshminarayanan3 1Department of Optometry, Medical Research Foundation, Chennai, Tamil Nadu, 600006, India; 2Shri Bhagwan Mahavir Vitreoretinal Services, Medical Research Foundation, Chennai, Tamil Nadu, 600006, India; 3Theoretical and Experimental Epistemology Lab, School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, CanadaCorrespondence: Janarthanam Jothi Balaji, Department of Optometry, Medical Research Foundation, 18, College Road, Nungambakkam, Chennai, Tamil Nadu, 600006, India, Tel +91 44-42271500, Email jothibalaji@gmail.comBackground: Posterior vitreous detachment (PVD) can result in serious pathologic events at the vitreoretinal interface. This study aims to assess the relationship between PVD, macular thickness (MT), and the foveal avascular zone (FAZ) in myopic eyes.Methods: This retrospective study evaluated 63 myopic subjects’ data who were examined between January 1 and June 30, 2019. The myopes were grouped on a severity scale, namely mild, moderate, high, and very high using their spherical equivalent (SE). The PVD classification was based on OCT images. The status of the PVD and MT were evaluated with the Macular Cube 200× 200 images, the FAZ with an OCTA Angioplex, and the dimensions were calculated using a customized algorithm.Results: The study population (114 eyes) had a median (range) age was 26.00 (22.00– 28.00) years and the females constituted 62.3% of the dataset. In this population, 10 eyes had no PVD in any quadrant, and 73 eyes had incomplete PVD in all four quadrants. The inferior quadrant had the maximum rate of PVD occurrences and the nasal quadrant had the least number of occurrences. High myopic eyes exhibited significantly increased low foveal volume (p = < 0.01). The inferior part of the para- and perimacular area showed a significant thinning in very high myopic eyes (p = < 0.050). The very high myopic eyes showed a significant alteration of FAZ’s circularity index (p = 0.002).Conclusion: In high and very high myopic eyes, an increasing trend of partial PVD is seen, most commonly in the inferior quadrant. A significant alteration in foveal volume and circularity index of the FAZ is seen in high and very high myopic eyes.Keywords: posterior vitreous detachment, foveal avascular zone, OCT, macular thickness, myopia

Mohamed Attia Ali Ahmed, Ahmed Shawkat Abdelhaleem Ophthalmology Department, Faculty of Medicine, Minia University, Minia, EgyptCorrespondence: Mohamed Attia Ali Ahmed, Email mohamedattia@mu.edu.eg; mohamedattia27@gmail.comPurpose: Comparison of early microvascular changes detected by optical coherence tomography angiography (OCTA) in patients with mild non-proliferative diabetic retinopathy (NPDR) with healthy volunteers.Patients and Methods: Forty-four eyes of 44 type-2 diabetic patients with mild non-proliferative diabetic retinopathy and 30 eyes of 30 age-matched healthy controls were imaged using OCTA to quantify microvascular changes and the FAZ quantitative parameters (area, perimeter, and circularity index); the values of patients and controls were then compared.Results: Macular vessel density, perfusion index, and circularity index values were reduced and positively correlated with visual acuity in patients (15.4 ± 2.6, 38.0 ± 6.7, 0.6 ± 0.06 and p = 0.003, 0.001, and 0.003, respectively). However, FAZ area and perimeter were found to be larger in patients than controls (0.30 ± 0.08, 2.5 ± 0.3 and p < 0.001).Conclusion: OCTA quantified vessel density and perfusion density were found to be correlated with visual acuity and FAZ parameters in patients with early NPDR; this could help in detecting early disease progression and modifying treatment decisions.Keywords: diabetic retinopathy, foveal avascular zone, optical coherence tomography angiography, vessel density, perfusion density

VK Viekash,1 Janarthanam Jothi Balaji,2 Vasudevan Lakshminarayanan3 1Department of Instrumentation and Control Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu, 620015, India; 2Department of Optometry, Medical Research Foundation, Chennai, Tamil Nadu, 600 006, India; 3Theoretical and Experimental Epistemology Lab, School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, N2L 3G1, CanadaCorrespondence: Janarthanam Jothi Balaji Tel +91 44-42271500Email jothibalaji@gmail.comIntroduction: Various ocular diseases and high myopia influence the anatomical reference point Foveal Avascular Zone (FAZ) dimensions. Therefore, it is important to segment and quantify the FAZs dimensions accurately. To the best of our knowledge, there is no automated tool or algorithms available to segment the FAZ’s deep retinal layer. The paper describes a new open-access software with a Graphical User Interface (GUI) and compares the results with the ground truth (manual segmentation).Methods: Ninety-three healthy normal subjects included 30 emmetropia and 63 myopic subjects without any sight-threatening retinal conditions, were included in the study. The 6mm x 6mm using the Angioplex protocol (Cirrus 5000 Carl Zeiss Meditec Inc., Dublin, CA) was used, and all the images were aligned with the centre of the fovea. Each FAZ image corresponding to dimensions 420× 420 pixels were used in this study. These FAZ image dimensions for the superficial and deep layers were quantified using the New Automated Software Method (NAM). The NAM-based FAZ dimensions were validated with the ground truth.Results: The age distribution for all 93 subjects was 28.02 ± 10.79 (range, 10.0– 66.0) years. For normal subjects mean ± SD age distribution was 32.13 ± 16.27 years. Similarly, the myopia age distribution was 26.06 ± 6.06 years. The NAM had an accuracy of 91.40%. Moreover, the NAM on superficial layer FAZ gave a Dice Similarity Coefficient (DSC) score of 0.94 and Structural Similarity Index Metric (SSIM) of 0.97, while the NAM on deep layer FAZ gave a DSC score of 0.96 and SSIM of 0.98.Conclusion: A clinician-based GUI software was designed and tested on the FAZ images from deep and superficial layers. The NAM outperformed the device’s inbuilt algorithm when measuring the superficial layer. This open-source software package is in the public domain and can be downloaded online.Keywords: image processing, foveal avascular zone, optical coherence tomography angiography, superficial retinal layer, deep retinal layer

Yuji Yoshikawa, Takuhei Shoji, Junji Kanno, Hisashi Ibuki, Kimitake Ozaki, Hirokazu Ishii, Hiromi Inami, Kei Shinoda Department of Ophthalmology, Saitama Medical University, Iruma, Saitama, JapanCorrespondence: Kei ShinodaDepartment of Ophthalmology, Saitama Medical University, 350-0495 Morohogo 38, Iruma, Saitama, JapanTel +81 49-276-1250Fax +81 49-295-8002Email shinodak@med.teikyo-u.ac.jpPurpose: Optical coherence tomography angiography (OCTA) allows noninvasive observation of the retinal vasculature, and image analysis can be used to calculate the retinal vessel density and foveal avascular zone (FAZ) area. A previous study showed that macular vessel density and the signal strength index (SSI) of OCTA images increased significantly after cataract surgery. However, the effect of aging on OCTA analysis remains unclear. This study aimed to investigate age-related changes in macular vascularization while excluding the effects of cataracts.Patients and Methods: OCTA imaging of the macula was performed in adult patients who had undergone cataract surgery between February 2018 and May 2019 and in young healthy participants between April 2017 and April 2018.Results: The median (quartiles) age of the overall study population was 59.0 (27.0, 69.0) years, and no severe refractive error was observed (axial length: 24.2 ± 1.3 [mean ± SD] mm; spherical equivalent: 0.75 [− 2.25, 0.00] diopter). When we investigated the relationship between macular vessel density and age after excluding the effects of cataracts, we found that the macular vessel density showed age-related changes even in the absence of the effects of the SSI. However, the FAZ area was not affected by age.Conclusion: Macular vessel density decreased with age, even when the effects of cataracts were excluded. The effects of age and cataracts should be considered when designing studies and interpreting OCTA findings of the retinal vasculature.Keywords: optical coherence tomography angiography, macular vessel density, foveal avascular zone, aging, cataract surgery

Tetsuya Hasegawa, Misaki Hirato, Chieko Kobashi, Aya Yamaguchi, Rina Takagi, Yoshiaki Tanaka, Toshikatsu Kaburaki, Akihiro Kakehashi Department of Ophthalmology, Saitama Medical Center Jichi Medical University, Saitama-shi, Saitama-ken, JapanCorrespondence: Akihiro KakehashiDepartment of Ophthalmology, Saitama Medical Center Jichi Medical University, Saitama-shi, Saitama-ken, JapanTel +81 48 647 2111Fax +81 48 648 5166Email kakeaki@omiya.jichi.ac.jpPurpose: To evaluate the foveal avascular zone (FAZ) and retinal structure in familial exudative vitreoretinopathy (FEVR).Patients and Methods: Eighteen eyes with stage 1 or 2 FEVR and 20 control eyes were evaluated. The central retinal thickness (CRT), foveal inner retinal thickness (IRT), surface retinal vessel density (SRVD), and deep retinal vessel density (DRVD) were measured using optical coherence tomography. The FAZ area was calculated using ImageJ software. The equivalent spherical value (SE) and axial length (AL) were measured.Results: The CRT (232.5± 3.086 vs 211± 12.6325 μm; p=0.003) and foveal IRT (15.83± 13.95 vs 0.9± 4.02 μm; p=0.002) were thicker in the FEVR group than in the control group. The surface FAZ area (0.265± 0.08 vs 0.364± 0.09 mm2; p=0.004) and the deep FAZ area (0.364± 0.1 vs 0.484± 0.11 mm2; p=0.03) were smaller in the FEVR group than in the control group. The SRVD values did not differ among the sectors, but the DRVD was higher in the FEVR group except for the inferior sector (superior, p=0.027; inferior, p=0.88; temporal, p=0.035; nasal, p=0.027). The SE and AL did not differ between the two groups. There were no correlations between the surface and deep layer FAZ area and age, CRT, SE, and AL. The surface, deep FAZ area, and foveal IRT were correlated negatively (surface, r = − 0.47, p=0.033; deep layer FAZ area, r = − 0.46, p=0.037).Conclusion: Eyes with FEVR have a smaller FAZ because the vascular structure in the inner retina remained in the fovea.Keywords: familial exudative vitreoretinopathy, optical coherence tomography angiography, foveal avascular zone

Tolga Kocatürk,1 Maja Zivkovic,2 Volkan Dayanır3 1Department of Ophthalmology, Aydın Adnan Menderes University, Aydın, Turkey; 2Department of Ophthalmology, Medical Faculty, University of Nis, Nis, Serbia; 3Department of Ophthalmology, Batıgöz Hospital, Izmir, TurkeyCorrespondence: Tolga KocatürkAydın Adnan Menderes Universitesi, Tip FakultesiHastanesi, Goz Hast, AD, Aydin, 09100, TurkeyTel +90 533 344 4111Fax +90 256 214 6495Email tolgakocaturk@gmail.comPurpose: To compare the vascular measurements obtained from fovea including foveal avascular zone (FAZ) with optical coherence tomography angiography (OCTA) between patients with exfoliation glaucoma (XFG) and healthy controls.Methods: This cross-sectional comparative study included 54 XFG patients and 94 healthy subjects. All subjects were given a complete ophthalmological examination including visual field testing, retinal nerve fiber layer and macular ganglion cell complex analysis. OCTA was performed to evaluate the vascular features of fovea including FAZ. The measurements of vessel density (VD), perfusion density (PD) and FAZ values were segmented and calculated using the inbuilt software on OCTA. Receiver operating characteristic (ROC) analyses were performed to determine the best cut-off values to detect the disease.Results: In the XFG group, decreased VD, PD and FAZ values were observed. ROC analysis showed an obvious separation, differentiating the patients with XFG from the healthy controls at cut-off value of 19.55 with a sensitivity (sen) of 92.3% and a specificity (spe) of 81.9%) for VD total and 21.20 (sen:100 and spe:78.7) for VD parafoveal; 0.36 (sen:98.1and spe:76.6) for PDtotal and 0.378 (sen:96.2and spe:84) for PDparafoveal; 0.635 (sen: 79.3 and spe:72) for FAZ circulatory index.Conclusion: The results support the findings of decreased microvascular density on foveal region in XFG. The cut off values of the changes in the foveal parameters in patients with exfoliation may be useful in evaluation of future glaucoma management to show how far a particular exfoliative eye is positioned from an healthy eye and how close to XFG.Keywords: exfoliation glaucoma, optical coherence tomography angiography, foveal avascular zone

Background: Posterior vitreous detachment (PVD) can result in serious pathologic events at the vitreoretinal interface. This study aims to assess the relationship between PVD, macular thickness (MT), and the foveal avascular zone (FAZ) in myopic eyes. Methods: This retrospective study evaluated 63 myopic subjects' data who were examined between January 1 and June 30, 2019. The myopes were grouped on a severity scale, namely mild, moderate, high, and very high using their spherical equivalent (SE). The PVD classification was based on OCT images. The status of the PVD and MT were evaluated with the Macular Cube 200× 200 images, the FAZ with an OCTA Angioplex, and the dimensions were calculated using a customized algorithm. Results: The study population (114 eyes) had a median (range) age was 26.00 (22.00– 28.00) years and the females constituted 62.3% of the dataset. In this population, 10 eyes had no PVD in any quadrant, and 73 eyes had incomplete PVD in all four quadrants. The inferior quadrant had the maximum rate of PVD occurrences and the nasal quadrant had the least number of occurrences. High myopic eyes exhibited significantly increased low foveal volume (p = < 0.01). The inferior part of the para- and perimacular area showed a significant thinning in very high myopic eyes (p = < 0.050). The very high myopic eyes showed a significant alteration of FAZ's circularity index (p = 0.002). Conclusion: In high and very high myopic eyes, an increasing trend of partial PVD is seen, most commonly in the inferior quadrant. A significant alteration in foveal volume and circularity index of the FAZ is seen in high and very high myopic eyes. [ABSTRACT FROM AUTHOR]

Supriya Dabir,1 Mohan Rajan,1 Liji Parasseril,1 Vaidehi Bhatt,2 Preetam Samant,3 CAB Webers,4 TTJM Berendschot4 1Department of Retina, Rajan Eye Care Pvt Ltd, Chennai, India; 2Rajiv Gandhi Medical College, Thane, India; 3Department of Retina, PD Hinduja Hospital and Medical Research Center, Mumbai, India; 4University Eye Clinic, Maastricht, the NetherlandsCorrespondence: Supriya DabirRajan Eye Care Hospital Pvt. Ltd, No. 5, Vidyodaya East 2nd Street, T. Nagar, Chennai, Tamil Nadu 600017, IndiaTel +919900974800Email supriad@gmail.comPurpose: Diabetic macular oedema (DME) is a vision-threatening complication of diabetic retinopathy. Spectral domain optical coherence tomography angiography (OCTA) is useful for assessing DME. We performed serial OCTA measurements before and after 3 monthly intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections to understand its relationship with best corrected visual acuity (BCVA), central macular thickness (CMT) and vascular indices.Methods: OCTA assessment consisting of 6 × 6 mm scans centred on fovea and en-face retinal angiograms were obtained. Scans were done at baseline and at 1 month following each of the 3 intravitreal injections of anti-VEGF (ranibizumab, Lucentis®).Results: Our prospective study included 24 eyes of 24 subjects, aged 63.0 ± 5.0 years. There was a mean gain of 0.07 LogMAR (3 letters) and reduction of CMT, vessel density (VD) and perfusion density (PD) by end of 3rd month. CMT was independently associated with improvement in BCVA. There were significant reductions in FAZ area, VD and PD over 3 months from baseline.Conclusion: At three months, intravitreal anti-VEGF therapy is associated with visual function recovery in DME, with reduction in CMT being the most reliable predictor of response. OCTA shows a reduction in VD and PD respectively suggestive of reduced macular perfusion in the short term. Simultaneous reduction in FAZ size can be due to reversal of manual displacement of the retinal capillaries resulting from resolution of intraretinal oedema.Keywords: diabetic macular oedema, superficial capillary plexus, vascular density, perfusion density, foveal avascular zone, optical coherence tomography angiography, macular ischemia

Purpose: Comparison of early microvascular changes detected by optical coherence tomography angiography (OCTA) in patients with mild non-proliferative diabetic retinopathy (NPDR) with healthy volunteers. Patients and Methods: Forty-four eyes of 44 type-2 diabetic patients with mild non-proliferative diabetic retinopathy and 30 eyes of 30 age-matched healthy controls were imaged using OCTA to quantify microvascular changes and the FAZ quantitative parameters (area, perimeter, and circularity index); the values of patients and controls were then compared. Results: Macular vessel density, perfusion index, and circularity index values were reduced and positively correlated with visual acuity in patients (15.4 ± 2.6, 38.0 ± 6.7, 0.6 ± 0.06 and p = 0.003, 0.001, and 0.003, respectively). However, FAZ area and perimeter were found to be larger in patients than controls (0.30 ± 0.08, 2.5 ± 0.3 and p < 0.001). Conclusion: OCTA quantified vessel density and perfusion density were found to be correlated with visual acuity and FAZ parameters in patients with early NPDR; this could help in detecting early disease progression and modifying treatment decisions. [ABSTRACT FROM AUTHOR]

Marwa Abdelshafy, Ahmed Abdelshafy Ophthalmology Department, Benha Faculty of Medicine, Benha University, Benha, EgyptCorrespondence: Marwa AbdelshafyOphthalmology Department, Benha Faculty of Medicine, Benha University, 1 El Amira Fawzya Street, Benha, Qalubiya Governorate 13512, EgyptEmail drmarwatabl2012@gmail.comAim: The aim of this study was to assess the correlation between different optical coherence tomography angiography (OCTA) parameters and the best corrected visual acuity (BCVA) in patients with diabetic retinopathy (DR).Patients and Methods: Sixty eyes of 60 participants were included in this prospective study: 40 diabetic patients [20 with non-proliferative diabetic retinopathy (NPDR group), 20 with proliferative diabetic retinopathy (PDR group)] and 20 age- and gender-matched normal healthy subjects (control group). After full ophthalmological examination and fundus fluorescein angiography, OCTA was performed for all participants. Quantitative OCTA parameters, such as the foveal avascular zone (FAZ) area, the superficial capillary plexus vessel density (%) (SCP-VD) and the deep capillary plexus vessel density (%) (DCP-VD) in, whole and parafoveal areas were measured. Correlations between BCVA and OCTA parameters were analyzed.Results: There were no statistically significant differences between groups regarding age, gender, refraction, macular thickness or intraocular pressure. The median (IQR) FAZ area was 0.42 (0.39– 0.46) mm2 in the NPDR group, 0.54 (0.45– 0.65) mm2 in the PDR group and 0.24 (0.21– 0.26) mm2 in the control group (P< 0.001). The FAZ area increased with increasing severity of DR. SCP-VD and DCP-VD showed significant differences between groups (P< 0.001). Vessel density (VD) was decreased in both DCP and SCP as DR progressed. There was a significant positive correlation between BCVA (LogMAR) and FAZ area. There were significant negative correlations between BCVA (LogMAR) and VD in both SCP and DCP. Stepwise multiple linear regression analysis demonstrated that SCP-VD in the whole area and DCP-VD in the parafoveal area were the best predictive factors for BCVA in the NPDR and PDR groups.Conclusion: With progression of DR, the VD decreased and the FAZ area increased, and both parameters were correlated with poor visual acuity. OCTA is a non-invasive tool which can be used to detect diabetic macular ischemia and help in the prediction of visual prognosis.Keywords: visual acuity, OCT angiography, vessel density, foveal avascular zone, diabetic retinopathy

Kazuyuki Kumagai,1 Nobuchika Ogino,2 Mariko Furukawa,1 Rieko Ooya,1 Eiji Horie3 1Kamiiida Daiichi General Hospital, Nagoya, Japan; 2Nishigaki Eye Clinic, Nagoya, Japan; 3Yata Eye Clinic, Izunokuni, Japan Purpose: The aim of this study was to determine whether the centripetal displacement of the capillaries in the macular region after vitrectomy is caused by internal limiting membrane (ILM) peeling. Methods: Eighteen patients with different types of retinal diseases but with a normal or approximately normal foveal contour underwent successful vitrectomy with (n=12) or without (n=6) ILM peeling. Optical coherence tomography angiography (OCTA) images of the inner retinal vascular plexus in the macular region were analyzed pre- and postoperatively. Four concentric polygonal areas were marked in the OCTA images with the corners selected to be easily identified by vessel bifurcations. The areas of the postoperative foveal avascular zone (FAZ) and the four polygonal regions at about 1 month postoperatively were compared to the baseline areas. Results: Vitrectomy was performed for eleven eyes with vitreomacular tractions, three with macular-on retinal detachments, and four with thin epiretinal membranes. A significant decrease in the FAZ area was observed postoperatively in only the ILM-peeled eyes (P=0.0002). The four polygonal areas in the ILM-peeled eyes decreased after surgery, and the decrease was fit by a linear regression line (R2=0.985–0.999; n=7). The time course of the postoperative decrease of the FAZ area was fit by a hyperbolic curve (R2=0.969–0.998; n=6). The average postoperative time required to reach one-half of the final FAZ area was 1.16 days (0.81–1.62 days). Conclusion: These findings suggest that ILM peeling causes an early centripetal displacement of the capillaries in the macular region. Keywords: epiretinal membrane, foveal avascular zone, internal limiting membrane, macular hole, optical coherence tomography angiography

Purpose: This study evaluates the effect of anti-vascular endothelial growth factor (anti-VEGF) therapy on microaneurysm changes and foveal avascular zone (FAZ) using optical coherence tomography angiography (OCTA) in patients with diabetic macular edema (DME). Design: Prospective observational study. Materials and Methods: This study involved patients with DME undergoing anti-VEGF treatment (aflibercept, ranibizumab, and bevacizumab). Macula OCTA images were obtained before (visit 0) and 1 month after (visit 1) anti-VEGF injection. Microaneurysm counts were performed, and the FAZ was evaluated in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). The differences in microaneurysms, FAZ, and clinical correlations were analyzed. Results: A total of 152 eyes were analyzed. The patients' mean age was 59 years. Bevacizumab was used in 69.7%, ranibizumab in 15.1%, and aflibercept in 15.1%. There was a significant reduction in the FAZ in the SCP and DCP between visits 0 and 1. All anti-VEGF medications reduced the number of microaneurysms (p< 0.01). After treatment, changes in the FAZ in SCP and DCP corresponded with changes in visual acuity (p< 0.01). Conclusion: Microaneurysms as detected by OCTA might serve as a biomarker for a clinical response to anti-VEGF treatment in the short term. The FAZ might also predict visual acuity improvement after anti-VEGF injection. Trial Registration: Thai Clinical Trials Registry (TCTR20161010005). [ABSTRACT FROM AUTHOR]

Background: Visual recovery following macula involving rhegmatogenous retinal detachment remains poorly understood. The aim of this work is to correlate the functional and the anatomical changes in retinal vasculature in the foveal avascular zone using optical coherence tomography angiography (OCTA) after successful retinal reattachment repair and correlate this data with retinal thickness and post-operative visual recovery. Methods: A prospective, comparative observational study of 28 eyes of 14 patients with 14 eyes undergoing macula off retinal detachment repair with pars plana vitrectomy, endo-laser and silicone oil-based tamponade compared with 14 fellow healthy eyes at 1, 6 and 12 weeks post-operative period. The study was conducted at the Research Institute of Ophthalmology, Giza, Egypt between February 2018 and August 2018. Results: The foveal avascular zone (FAZ) area in the patients group was not significantly different compared to the control group and was found to be negatively correlated with the central retinal thickness in both the study and control group. The superficial capillary plexus (SCP) area at the FAZ was significantly larger than the deep capillary plexus (DCP) area at the FAZ in both the study and control group over the follow-up period. The DCP area at the FAZ was significantly larger at the 3rd follow-up than the 1st follow-up. The SCP FAZ area was significantly larger than the DCP FAZ area in both the study and control group over the follow-up period. BCVA was found to be negatively correlated to the retinal thickness of the temporal 3 mm paracentral quadrant with no correlation with central foveal thickness (CFT) and the FAZ area. Conclusion: Optical coherence tomography (OCT) and OCTA are valuable noninvasive imaging tools to monitor and predict the structural changes at the foveal avascular zone during the recovery phase after successful retinal reattachment involving macula. [ABSTRACT FROM AUTHOR]

Christine A Kiire, Rupal Morjaria, Anna Rudenko, Alexina Fantato, Lewis Smith, Amy Smith, Victor Chong Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK Purpose: Pegaptanib has been shown to be effective in treating diabetic macular edema (DME). In the original Phase II/III trial, however, patients with macular ischemia were excluded. In this study, we treated patients with ischemic DME. Methods: Macular ischemia was defined as a 30% increase in the area of the foveal avascular zone (FAZ) at 45 seconds on fundus fluorescein angiography. In addition, the participants had diffuse foveal-involving DME with a central subfield thickness (CST) of >300 µm on spectral-domain optical coherence tomography. Five intravitreal pegaptanib injections were given 6 weeks apart. The final study visit was 6 weeks after the fifth injection. The primary outcome was change in the size of FAZ. Secondary outcomes were change in best-corrected visual acuity (BCVA) and the change in CST. Results: Thirty participants were enrolled. Three were unable to complete the full course of treatment. Their outcomes were carried forward for the first part of this analysis. There was no statistically significant change in the mean size of the FAZ from baseline to the final visit. Subclassifying participants as those with minimal/moderate ischemia (16 participants, FAZ area 1,000 pixels) also showed no statistically significant change in the mean area of the FAZ. On average, BCVA increased and CST decreased from baseline to the final visit, but these changes were not statistically significant. Using per protocol analysis on those participants who completed the full course of treatment, the mean BCVA increased from 49.2 to 53.9 letters (P=0.046). Conclusion: In this study, intravitreal injection of pegaptanib did not significantly alter the size of the FAZ in participants with varying degrees of ischemic DME. There was, however, a significant improvement in mean BCVA in those who completed the treatment course. Keywords: macular ischemia, anti-VEGF, pegaptanib, diabetic macular edema

Purpose: To investigate changes in the area of the foveal avascular zone (FAZ) in patients with retinal vascular disease. Patients and methods: This retrospective, consecutive study examined 53 eyes of 53 patients with macular edema due to branch retinal vein occlusion in 25 patients (47.2%) and nonproliferative diabetic retinopathy in 28 patients (52.8%). The macular edema was treated with an intravitreal injection of 0.05 mL equal to 1.25 mg bevacizumab. Before and 6-8 weeks after the injection, best corrected visual acuity, slit lamp biomicroscopy of the anterior segment and fundus, optical coherence tomography, and fluorescein angiography were conducted. The FAZ was manually circumscribed on early-phase angiography images and the area of the FAZ was measured. Results: The preoperative overall mean FAZ area was 0.327 ± 0.126 mm² (median 0.310 mm²). At the control consultation, the overall mean area was significantly larger (0.422 ± 0.259 mm²; median 0.380 mm²; P < 0.001). In the nonproliferative diabetic retinopathy subpopulation, the mean area was 0.361 ± 0.129 mm² (median 0.330 mm²) before bevacizumab application and 0.434 mm² at the follow-up visit (mean increase 0.071 mm²/19.7%). In the branch retinal vein occlusion group, the baseline FAZ area was 0.290 ± 0.115 mm² and 0.407 ± 0.350 mm² at follow-up (median 0.330 mm²; mean increase 0.117 mm²/40.3%). No cases of severe operation-associated complications were observed. Conclusion: The results confirm the safety of intravitreal bevacizumab injection in patients with macular edema due to nonproliferative diabetic retinopathy and branch retinal vein occlusion. The enlargement of the FAZ could be equivalent to an increase in retinal ischemia. These results may be transient; a potential vascular risk, however, when applying antivascular endothelial growth factor therapy in eyes with preexistent vascular disease must be considered. [ABSTRACT FROM AUTHOR]