Research Article Optic Disc Vascularization in Glaucoma: Value of Spectral-Domain Optical Coherence Tomography Angiography

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1 Jounal of Ohthalmology Volume 26, Aticle ID , 9 ages htt://dx.doi.og/.55/26/ Reseach Aticle Otic Disc Vasculaization in Glaucoma: Value of Sectal-Domain Otical Coheence Tomogahy Angiogahy Piee-Maxime Lévêque, Piee Zéboulon, Emmanuelle Basnu,,2 Chistohe Baudouin,,2,3 and Antoine Labbé,2,3,4 CHNO des Quinze-Vingts, DHU Sight Restoe, INSERM-DHOS CIC, 28 ue de Chaenton, 752 Pais, Fance 2 Sobonne Univesités, UPMC, INSERM, CNRS, Institut de la Vision, 7 ue Moeau, 752 Pais, Fance 3 Deatment of Ohthalmology, Amboise Paé Hosital (AP-HP), Univesity of Vesailles Saint-Quentin-en-Yvelines, 55 Avenue de Pais, 78 Vesailles, Fance 4 Deatment of Ohthalmology III, Quinze-Vingts National Ohthalmology Hosital, 28 ue de Chaenton, 752 Pais, Fance Coesondence should be addessed to Antoine Labbé; d.antoinelabbe@gmail.com Received 3 Octobe 25; Revised 2 Januay 26; Acceted 24 Januay 26 Academic Edito: Paolo Fogagnolo Coyight 26 Piee-Maxime Lévêque et al. This is an oen access aticle distibuted unde the Ceative Commons Attibution License, which emits unesticted use, distibution, and eoduction in any medium, ovided the oiginal wok is oely cited. Puose. To detect changes in otic neve head (ONH) vasculaization in glaucoma atients using sectal-domain OCT angiogahy (OCT-A). Mateial and Method. Fifty glaucoma atients and 3 nomal subjects wee evaluated with OCT-A (AngioVue, Otovue). The total ONH vessel density and temoal disc vessel density wee measued. Clinical data, visual field (VF) aametes, and sectal-domain OCT evaluation (RNFL: etinal neve fibe laye thickness, GCC: ganglion cell comlex thickness, and im aea) wee ecoded fo glaucoma atients. Coelations among total and temoal ONH vessel density and stuctual and VF aametes wee analyzed. Results. In the glaucoma gou, total and temoal ONH vessel density wee educed by 24.7% (.42 vesus.547; <.) and 22.88% (.364 vesus.472; =.), esectively, as comaed with the contol gou. Univaiate analysis showed significant coelation between im aea (mm 2 ) and temoal ONH vessel density ( =.623; <.)andtotalonhvesseldensity( =.69; <.). Significant coelations wee found between temoal and total ONH vessel density and RNFL, GCC, VF mean deviation, and visual field index. Conclusion. In glaucoma atients OCT-A might detect educed ONH blood vessel density that is associated with stuctual and functional glaucomatous damage. OCT-A might become a useful tool fo the evaluation of ONH micociculation changes in glaucoma.. Intoduction Although elevated intaocula essue (IOP) is the main isk facto fo glaucoma, high numbes of atients also develo glaucoma with nomal IOP levels []. Theefoe, othe isk factos and in aticula vascula isk factos have been imlicated in the athogenesis of glaucoma [2]. These vascula factos include autoegulation of the blood flow (BF) in the otic neve head (ONH), local vasosasm, ateial hyetension, and noctunal hyotension [3]. Imaied micociculation in the ONH may contibute to the initiation and ogession of glaucomatous neuoathy. BF in the ONH is sulied by two ateial systems: the cental etinal atey in sueficial layes and the osteio ciliay atey in deee layes (elamina and lamina cibosa and etolamina stuctues) [4]. It has been oosed that the main athologic changesinglaucomaaelocatedinthedeeonhegion, sulied by ciliay ateies [5]. Consequently, seveal techniques have been oosed to measue otic disc efusion [6, 7]. Lase Dole velocimety has been used to identify the maximum BF velocity esent in lage etinal vessels [6]. Othe methods such as scanning lase Dole flowmety [8] and lase seckle flowgahy [9] wee also develoed to measue disc efusion. Dole otical coheence tomogahy (OCT) has been used to measue the total etinal blood flow aound the ONH []. Using this imaging technique, BF in lage vessels of the ONH can be quantified, but the study of the micovascula stuctue is imossible due to the low velocity of the BF in small vessels. The micoshee method, a method

2 2 Jounal of Ohthalmology basedonadioactivesolidmicosheesinjectedintothe systemic ciculation, has also ovided evidence that the lase seckle flowgahy is caable of assaying BF in the dee ONH egion but only in exeimental glaucoma models []. Moe ecently, Jia et al. develoed a new method to study in vivo the ONH micociculation in glaucoma atients: the slit sectum amlitude-decoelation angiogahy (SSADA) algoithm [2]. It ovides high-quality theedimensional (3D) angiogahy using ulta-high-seed swetsouce OCT [3]. These authos found educed disc efusion in a gou of atients with ealy glaucoma and established a link between ONH vessel density and visual field atten standad deviation (PSD) using a custom swet-souce OCT device [4]. The OCT angiogahy with SSADA may be moe eliable than LSFG o LDF, offeing bette intavisit eeatability and intevisit eoducibility [4 6]. The objective of the esent study was to detect changes in ONH vasculaization by comaing nomal subjects and glaucoma atients using a commecial sectal-domain OCT angiogahy (OCT-A) device. 2. Methods 2.. Study Poulation. This coss-sectional obsevational study was conducted at the Quinze-Vingts National Ohthalmology Hosital, Pais, Fance, fom Januay to Setembe 25 afte aoval of ou Institutional Review Boad. The study adheed to the tenets of the Declaation of Helsinki andinfomedconsentwasobtainedfomallsubjects.patients followed u at the Quinze-Vingts National Ohthalmology Hosital fo glaucoma wee consecutively included. Inclusion citeiaweechonicglaucomadefinedasglaucomatousotic disc neuoathy and chaacteistic visual field (VF) loss based on the citeia of the Ocula Hyetension Teatment Study [7].TheglaucomatousVFlosswasdefinedasaglaucoma hemifield test gaded outside nomal limits and a cluste of thee contiguous oints at the 5% level on the atten deviation lot, using the theshold test stategy with the 24-2 testattenofthehumheyfieldanalyzeii[8].patients with diabetic etinoathy, othe diseases that may cause visual field loss o otic disc abnomalities, and inability to clinically view o hotogah the otic discs due to media oacity o ooly dilating uil wee excluded. Fo all glaucoma atients, the following data wee ecoded: age, gende, best coected visual acuity (BCVA) on a logaithmic scale, IOP (mmhg), cental coneal thickness (CCT), tye of glaucoma, and cu/disc atio. IOP was measued using the Goldmann alanation tonomete. Fo each eye, IOP value eesented the mean value of two IOP eadings. CCT was measued with an A-scan ultasound (A- Scan Pachymete, Ultasonic, Exton, PA, USA). The mean etinal neve fibe laye (RNFL) thickness, mean ganglion cell comlex (GCC) thickness, and disc im aea wee also evaluated (Cius sectal-domain OCT, Cal Zeiss Meditec Inc., Dublin, IE). VF tests wee efomed with a Humhey Field Analyze II (Cal Zeiss Meditec Inc.) set fo 24-2 to collect mean deviation (MD), atten standad deviation (PSD), and the visual field index (VFI). The Bascom Palme (Hoda-Andeson-Paish) glaucoma staging system (GSS) based on VF esults was selected to classify atients as having mild, modeate, and sevee glaucoma [9]. Healthy age-matched contols wee also included. Nomal subjects had IOP < 2mmHgwithclinicallynomal ONHandnohistoyofoculaosystemicdisease.Focontol subjects, demogahic data and IOP wee ecoded Otical Coheence Tomogahy. We used the commecially available sectal-domain OCT RT XR Avanti with the AngioVue softwae (Otovue, Inc., Femont, CA, USA). It detects BF in an acquied volume using the SSADA [2]. The instument used fo OCT-A images is based on the AngioVue Imaging System (Otovue, Inc., Femont, CA, USA) to obtain amlitude decoelation angiogahy images. This instument has an A-scan ate of 7, scans e second, using a light souce centeed on 84 nm and a bandwidth of 5 nm. Each OCT-A volume contains A-scans with two consecutive B-scans catued at each fixed osition befoe oceeding to the next samling location. Slit sectum amlitude-decoelation angiogahy was used to extact the OCT angiogahy infomation. Each OCT-A volume is acquied in thee seconds and two othogonal OCT-A volumes wee acquied in ode to efom motion coection to minimize motion atifacts aising fom micosaccades and fixation changes. The softwae analyzes the amlitude of vaiation of the OCT signal ove time fo evey location acquied and calculates decoelation. Static tissue yields low decoelation values as the signal vaies a little ove time, and BF yields high decoelation values because moving ed blood cells coss the OCT beam and cause the signal amlitude to vay aidly ove time. A theshold decoelation value is theefoe used to disciminatebffomstatictissue[2,2].theangiogahy infomation dislayed was the aveage of the decoelation values when viewed eendiculaly though the thickness evaluated. This mas all the detected vessels in the acquied volume. The AngioVue softwae (Otovue) can then calculate a quantitative vaiable: the total suface of the flowing vessel ontheenfaceojection.theighteyefomeachnomal subject was scanned. Fo glaucoma atients, we decided to analyze the most sevee eye as detemined by the MD Image Acquisition and Pocessing. Fist, each subject undewent one set of two scans on the macula egion. The SSADA algoithm equies the use to define a theshold of detection of ciculating vessels [3]. Jia et al. descibed amethodtocalculatetheaoiatetheshold.thecental avascula zone was defined as a noise egion and the mean decoelation value of the whole avascula zone was calculated. A theshold one standad deviation above the mean avascula decoelation value was defined as ciculating vessels. Then we efomed one set of two 3 3mm scans on the ONH. We used the neual canal oening, which is the temination of the etinal igment eithelium/buch membane comlex, to define the ONH magin [22]. The volumes analyzed wee defined by both a cicula suface on the en face ojection and the anteoosteio boundaies, thus ceating a cylinde. A cicle on the en face ojection

3 Jounal of Ohthalmology 3 (a) (b) (c) Figue : Total (a) and temoal (b) ONH acquisition in a nomal atient. Total (c) and temoal (d) ONH acquisition in a glaucoma atient. (d) and anteoosteio limits defines each cylinde. We studied the total ONH flow aea (mm 2 ), eesenting the numbe of vessels, detected fom all the deths of the disc, fom the to of the ONH (inne suface) to the lamina cibosa. Next, the total ONH vessel density (%) was calculated by dividing flow aea by the otic disc suface (πr 2 ). The ONH temoal egion (detemined by the temoal disc between the temoal ateies and veins) was also studied to avoid BF due to majo sueio and infeio banches of etinal vessels in ode to focus on the ONH lamina micovasculatue (Figue ). Then we measued the temoal disc flow aea (mm 2 ) and calculated the temoal disc vessel density by dividing the temoal disc flow aea by the temoal disc suface (πr 2 temoal). The total and temoal otic disc vessel densities, obtained as the atio of the otic disc flow aea to the otic disc suface, wee calculated to account fo the inteeye diffeences in total and temoal otic disc suface aeas. Image quality was detemined fo all OCT-A scans. Poo quality images with a signal stength index (SSI) < 4 o image sets with emaining motion atifacts wee excluded fom the study analysis [23] Reoducibility and Reeatability. Measuement eeatabilityofthediscflowaeawasevaluatedfomtheesets of acquisitions fom a subset of 6 nomal subjects within a single visit. The intavisit coefficient of vaiation (CV) was calculated by comaing these thee measuements. Intevisit eoducibility was obtained fom thee sets of scans efomed on thee seaate visits fom the same subset of nomal subjects Statistical Analysis. Mann-Whitney tests wee used to comae the aveage values of the measuements between nomal and glaucomatous eyes. Linea egession analysis was used in the contol gou to investigate whethe the measuement of ONH vessel density was affected by age, gende, and IOP. Univaiate analysis with the Peason coelation test and multivaiate analysis with the ANCOVA test wee efomed to study the coelation between ONH vessel density and othe vaiables: age, RNFL thickness, GCC, im aea, MD 24-2, and PSD Results 3.. Demogahic and Clinical Data. Fifty glaucoma atients and 3 nomal subjects wee included in this study. Thee was

4 4 Jounal of Ohthalmology Table : Qualitative and quantitative demogahic data. IOP: intaocula essue; F: female, M: male. Nomal Glaucoma value Qualitative demogahic data (n =3) % (n=5) % Gende F NS M Family histoy of glaucoma < Ethnic oigin Afican Caucasian Asian 2 4 Hisanic 2 4 Maghebi Quantitative demogahic data Mean SD Mean SD Age (yeas) NS IOP (mmhg) no diffeence between the two gous concening age, gende, and ethnic oigin. A family histoy of glaucoma was found in 52% of glaucoma atients and % of contol subjects ( <.). IOP was 7.6 mmhg and 4.4 mmhg in the glaucoma and contol gou, esectively ( =.22). The demogahic data ae summaized in Table. Regading the tye of glaucoma, 43 atients (86%) had oen-angle glaucoma (OAG) and seven atients (4%) had angle-closue glaucoma (ACG). Twenty-thee atients (46%) had mild glaucoma, eight (6%) had modeate glaucoma, and9(38%)hadseveeglaucoma.meanrnflthickness, GCC thickness, and im aea wee ± 2.6 μm, 63.6 ± 9.7 μm, and.786 ±.29 mm 2 in the glaucoma gou, esectively. The esults of the glaucoma atients clinical data ae summaized in Table ONH Blood Flow Evaluation. The en face ojection angiogams showed that nomal discs had a dense micovascula netwok, esecially in the temoal egion, comaed with glaucomatous discs (Figue ). Total ONH vessel density was educed by 24.7% (.42 ±.7 vesus.547 ±.77, <.) in the glaucoma gou as comaed with the contol gou. Temoal disc vessel density was significantly educed by 22.88% (.364 ±.5 vesus.472 ±.5, =.) in the glaucoma gou as comaed with the contol gou. Moeove, SSI and the decoelation theshold wee highe in the contol gou (72.3 vesus 6.8, <.,and.95 vesus.85, =., es.). The intavisit CV was 6.7%. The intevisit CV was 6.48%. The esults of the ONH BF evaluation ae summaized in Table 3. Intheglaucomagou,univaiateanalysisshowedthat total ONH vessel density was significantly associated with stuctual vaiables including im aea ( =.69; <.), RNFL thickness ( =.46; <.3), and GCC thickness ( =.337; =.7) (Figue 2). Total ONH vessel density was also associated with the functional vaiables VFI Table 2: Quantitative and qualitative clinical data. OAG: oenangle glaucoma; ACG: angle-closue glaucoma. Visual field and OCT sectal-domain testing. MD: mean deviation; PSD: atten standad deviation; VFI: visual field index; RNFL: etinal neve fibe layes; GCC: ganglion cell comlex. Glaucoma Qualitative clinical data (n =5) % Tye OAG ACG 7 4 Stage Mild Modeate 8 6 Sevee 9 38 Quantitative clinical data Mean SD log AV Coneal cental thickness (μm) Cu/disc atio MD 24-2 (db) PSD 24-2 (db) VFI RNFL thickness (μm) GCC thickness (μm) Rim aea (mm 2 ) ( =.339; =.7) and MD 24-2 ( =.3; =.38). The esults of these coelations ae summaized in Table 4. In the multivaiate analysis whee total ONH vessel density was consideed as a deendent vaiable, im aea was the dominant exlanatoy vaiable, accounting fo 38.9% of the vaiance (R 2 ). In this multivaiate model, RNFL thickness, GCC thickness, and VF aametes (MD 24-2 and VFI)

5 Jounal of Ohthalmology 5 Table 3: OCT angiogahy measuements. SSI: stength signal index. OCT angiogahy measuements Nomal Glaucoma value Mean SD Mean SD Theshold SSI Total ONH vessel density Temoal disc vessel density Glaucoma stage Total ONH vessel density Temoal disc vessel density Mean SD Mean SD Mild Modeate Sevee Temoal disc vessel density Total ONH vessel density Linea egession temoal disc vessel density with im aea (R 2 =.389) Rim aea Linea egession total ONH vessel density and im aea (R 2 =.37) Rim aea Figue 2: Linea egession analysis fo temoal disc vessel density, total ONH vessel density, and im aea. wee not statistically associated with ONH vascula density (Table 5). Consideing temoal disc vessel density, in univaiate analysis, a coelation was obseved with im aea ( =.624; <.) (Figue 2), RNFL thickness ( =.448; =.), and GCC thickness ( =.395; =.4). Temoal disc vessel density was also associated with VFI ( =.423; =.2), MD 24-2 ( =.385; =.7), but not with PSD 24-2 (Table 6). In a multivaiate model studying temoal disc vessel density as a deendent vaiable, im aea was also the dominant exlanatoy vaiable, accounting fo 39% of the vaiance (R 2 ). RNFL thickness, GCC thickness, and VF aametes (MD 24-2, VFI) wee not associated with temoal disc vessel density (Table 7). 4. Discussion In this study, we eot the use of sectal-domain OCT angiogahy to measue ONH efusion in glaucoma. We tageted two egions, the whole disc and a temoal disc aea,tocomaethetwogous.weshowedasignificant diffeence in ONH vascula density between glaucoma and nomal atients. The diffeence was simila fo the total and temoal vascula aea, with a decease of ONH efusion as comaed with contols by 24.7% and 22.9%, esectively. We obseved a significant coelation between ONH efusion and stuctual and functional glaucoma damage. Moeove, the multivaiate egession models confimed the elation between disc im aea and ONH efusion (total and temoal vessel density). These esults emhasized the elation between ONH BF and stuctual loss in glaucoma. Inaevioussimilastudyusingaototyeofswetsouce angio-oct, Jia et al. studied ONH total BF with the SSADA. These authos found a coelation between the disc flow index and PSD, but they did not obseve a coelation with stuctual vaiables such as the C/D atio, im aea, o RNFL thickness [4]. Although alteed micociculation is eoted to be associated with otic neve head changes in glaucoma [24], these authos suggested that the flow index was indeendent infomation on glaucoma seveity that is not exlained by stuctual vaiables alone. The diffeences between ou two studies can be exlained by andom vaiationsduetothesmallsamlesizeofthestudyeoted by Jia et al. (24 nomal subjects and glaucoma atients). Moeove,mostoftheiglaucomaatientshadealy-stage disease. In ou study, 38% of the atients had sevee glaucoma with advanced stuctual changes. The coelations we obseved between ONH efusion and stuctual aametes such as im aea, RNFL thickness, and GCC thickness could be exlained by the moe advanced glaucoma cases included in the esent study. Inteestingly, in these moe advanced glaucoma atients, we also found a low but significant

6 6 Jounal of Ohthalmology Table 4: Peason coelation coefficient matix fo visual field, stuctual vaiables, and ONH total vessel density in subjects with glaucoma. MD: mean deviation; PSD: atten standad deviation; VFI: visual field index; RNFL: etinal neve fibe layes; GCC: ganglion cell comlex; total ONH density: total ONH vessel density; SSI: stength signal index. Statistically significant coelations with total ONH vessel density ae in bold. Vaiable Total ONH density SSI VFI PSD 24-2 MD 24-2 GCC Rim aea RNFL Age Total ONH density SSI VFI PSD 24-2 MD 24-2 GCC thickness Rim aea RNFL thickness Age Table5:MultivaiatemodelfototalONHvesseldensityR 2 =.387. Vaiable Sloe value MD VFI..955 GCC thickness Rim aea.269. RNFL thickness MD: mean deviation; VFI: visual field index; RNFL: etinal neve fibe layes; GCC: ganglion cell comlex. Statistically significant coelations with total ONH vessel density ae in bold. coelation with VF vaiables in univaiate analysis, as did Jia et al. These esults ae also in accodance with the study by Liu et al. using OCT-A (RTVue-XR; Otovue, Inc.) that showed educed eiaillay vessel density in glaucoma atients coelated with VF indexes [23]. In a ecent study, Wang et al. comaing otic disc efusion with OCT-A between 62 glaucoma atients and 2 contol subjects found simila esults with educed disc vessel density in the glaucoma gou coelated with stuctual aametes such as the GCC [25]. The SSADA algoithm equies the use to define a theshold of ciculating vessel detection. Jia et al. descibed a method to calculate the aoiate theshold using the cental avascula zone as a noise egion and calculating the mean decoelation value of the whole avascula zone. With thei OCT-A ototye, they set the theshold two standad deviations above the mean avascula zone decoelation. In the esent study, using the commecially available sectaldomain OCT RT XR Avanti with the AngioVue softwae (Otovue, Inc. Femont, CA, USA), we could not detect obvious ciculating vessels using the same theshold as Jia et al. Theefoe we set ou theshold one standad deviation above the mean avascula decoelation value. This diffeence might be exlained by the diffeence in OCT-A hadwae and softwae used in the two studies. The esults obtained with OCT-A confimed the findings of seveal othe techniques that eoted ONH BF changes in glaucoma. Hais et al. measued ONH BF with diffeent imaging technologies including colo Dole imaging, confocal scanning lase ohthalmoscoic angiogahy, lase blood flowmety, o scanning lase Dole flowmety and demonstated educed ONH efusion in glaucoma atients [6, 7]. Disc BF was also investigated by fluoescein angiogahy (FA) in seveal studies showing diffuse disc hyoefusion and ONH fluoescein filling defects in glaucomatous atients [26]. Nevetheless, FA is not commonly used fo monitoing glaucoma because of quantification oblems and its otential side effects as an invasive technique [27]. Deceased ONH BF in glaucoma atients vesus contols and inceased viscosity in the aillay micovascula netwok wee eoted with the use of the lase Dole velocimete [28]. Using scanning lase Dole flowmety, Michelson et al. showed deceased eiaillay etinal BF and neuoetinal BF comaing glaucoma atients to contol subjects [29]. Hafez et al. also found lowe ONH BF in glaucoma atients and suggested a coelation between visual field defects and ONH efusion [3]. Using lase seckle flowgahy, othe authos eoted educed BF in glaucoma atients and found a coelation between BF and MD and RNFL thickness [3]. Wang et al. confimed a high coelation between the BF eduction measued by lase seckle flowgahy and the micoshee method, oviding evidence that this technique is caable of assaying BF fo a citical dee ONH egion [].

7 Jounal of Ohthalmology 7 Table 6: Peason coelation coefficient matix fo visual field, stuctual vaiables, and temoal disc vessel density in subjects with glaucoma. MD: mean deviation; PSD: atten standad deviation; VFI: visual field index; RNFL: etinal neve fibe layes; GCC: ganglion cell comlex; SSI: stength signal index. Statistically significant coelations with temoal disc vessel density ae in bold. Vaiable Temoal disc density SSI VFI PSD 24-2 MD 24-2 GCC Rim aea RNFL Age Temoal disc density SSI VFI PSD 24-2 MD 24-2 GCC thickness Rim aea RNFL thickness Age Table7:MultivaiatemodelfotemoaldiscvesseldensityR 2 =.39. Vaiable Sloe value MD VFI.2.68 GCC thickness..69 Rim aea.3. RNFL thickness..648 MD: mean deviation; VFI: visual field index; RNFL: etinal neve fibe layes; GCC: ganglion cell comlex. Statistically significant coelations with temoal disc vessel density ae in bold. The use of OCT-A to evaluate ONH BF may ovide a newtooltoinvestigatetheoleofthemicovasculatueinthe athohysiology of glaucoma and its changes with glaucoma ogession. One of the longstanding questions is whethe educed BF is a eexisting athologic change o a consequence of glaucomatous otic atohy [32]. This is difficult to detemine in at because a substantial otion of etinal ganglion cells/axons may have aleady become degeneated, even at an ealy stage of glaucoma [33]. Comomised blood suly and theefoe educed ocula BF due to inceased IOPovasculadysegulationhasbeenimlicatedinthe athogenesis of the disease [7, 32]. In tems of lamina caillay volume flow, Bugoyne et al. hyothesized that, within the lamina, connective tissue IOP-elated stain has both diect and indiect effects on axonal nutition and that axonal ischemia can esult fom eithe IOP-induced occlusion of the lamina caillaies (diect effect) o deceased diffusion of nutients (indiect effect), o both. In tems of only the etolamina effects on BF, the level of IOP-elated stain within the eiaillay sclea may significantly affect volume flow though the scleal banches of the shot osteio ciliay ateies. This hyothesis suggests that vascula mechanisms damaging the ONH ae not necessaily IOP-indeendent and ooses a logic fo undestanding the comlicated inteaction between these thee imotant factos (IOP, volume BF, and nutient delivey) within the tissues of the ONH [34]. Ou study has limitations that need to be consideed when inteeting the esults. Nomal and glaucomatous eyes have been classified accoding to the visualization the ONH andnovisualfieldwasefomedtocontolsubjects.as OCT-A was used to evaluate ONH vasculaization, we may have inceased the chance of finding significant diffeences between gous. Similaly, by selecting the wost eye of glaucomatous atients we may have influenced the esults. Nevetheless, this limitation has not influenced the analysis of coelation of OCT-A esults and otic neve aametes fo glaucoma atients as this gou was classified accoding to the esults of VF. The esults of the esent study suggest that sectaldomain OCT angiogahy might detect educed ONH blood flow in glaucoma atients. These ONH blood flow changes wee associated with stuctual and functional glaucomatous alteations. New studies ae needed to evaluate the exact otential of OCT-A in glaucoma. Conflict of Inteests The authos declae that thee is no conflict of inteests egading the ublication of this ae. Refeences [] D. C. Boadway and S. M. Dance, Glaucoma and vasosasm, Bitish Jounal of Ohthalmology, vol.82,no.8, , 998.

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