Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography.

PURPOSE: To compare the retinal vessel density and glaucomatous parameters in primary angle closure glaucoma (PACG), to evaluate the diagnostic and monitoring abilities of the peripapillary and macular vessel density in the progression of glaucoma.
METHODS: This was a observational, prospective and cross-sectional study. According to Glaucoma Staging System, 218 eyes (116 participants) were divided into 5 groups: no glaucoma, early glaucoma, moderate glaucoma, advance glaucoma, severe glaucoma. All participants underwent a comprehensive ocular examination, which included corrected distance visual acuity measurement, slit-lamp biomicroscopy, intra ocular pressure (IOP), gonioscopy, fundus examination, stereoscopic optic disc photography, Humphrey visual field test(VF), peripapillary and macular optical coherence tomography angiography(OCTA) scan. SPSS software was used to calculate and compare retinal vessel density (peripapillary vessel density, PVD and macular vessel density, MVD) and glaucomatous parameters (mean deviation (MD),pattern standard deviation(PSD), retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer(GCIPL),rim area, average cup/disc(C/D) ratio).
RESULTS: The GCIPL thickness, RNFL thickness, PVD and MVD are significantly reduced in PACG. There were significant differences in all measurements among the groups (P<0.01).Reduced peripapillary and macular vessel density in glaucoma were detected and a statistically significant correlation with glaucoma stages (P<0.01). In addition, the results of retinal vessel density, reduced RNFL thickness and GCIPL thickness were also statistically related to the stage of glaucoma. As expected, the rim area was significantly smaller with higher C/D area ratios in glaucomatous eyes corresponding to the severity of disease.
CONCLUSIONS: The changes of PVD and MVD had strongly positive correlation with GCIPL thickness and RNFL thickness, had negative correlation with the severity of glaucoma, which meant the more severe the glaucoma was, the lower PVD and MVD were. Compared to traditional glaucoma staging system judged by VF, the changes of PVD and MVD obtained by OCTA might be a new method to grade the stage of glaucoma. These findings theorize that the changes of PVD and MVD may be better facilitated for the observation and monitoring of glaucoma progression.

Introduction

Glaucoma is the leading cause of irreversible blindness in the world, around 65 million people suffer from this disease. [1] It is well documented that early diagnosis, early treatment and monitoring of the progression are the key determinants to reduce the risk of irreversible vision loss.

Though, the pathogenesis of glaucoma is not fully understood, reducing IOP is still the only effective method to slow glaucoma damage [2].As we know, structural damage occurs prior to functional damage in glaucoma. Functional, such as VF may be not appropriate to diagnose the earliest stages of glaucoma or judge the progression of glaucoma. Because of a significant amount of ganglion cell (GC) loss is expected to occur (25–50%) before functional deficits[3].Peripapillary retinal nerve fiber layer (PRNFL) thinning, GC thickness reduction and neuro-retinal rim narrowing are the available good standards for diagnosing and monitoring the progression of glaucoma, while detection of VF defects is indispensable for monitoring the functional decline.

With the recent development of OCTA, which can provide us with qualitative and quantitative information of the microvasculature in various retinal regions, including the optic nerve, peripapillary retina, and macula, we can easily get insight of the relationship between retinal blood flow various and visual functional damage. Some studies have recently suggested that reduced ocular blood flow is a primarily independent metric of visual function outside of other structural parameters, supporting a vascular role in the development of glaucoma [4-6].In the past few years, some research has shown decreased peripapillary retinal and macular perfusion in glaucomatous eyes correlating with VF damage [7-8].These studies however focused more on primary open angle glaucoma (POAG). Due to anatomical variations, the prevalence of primary angle closure glaucoma (PACG) is greater than POAG in Asia. The main purpose of this study was to compare the retinal vascular density and glaucomatous parameters in PACG and to evaluate the diagnostic and administrative abilities of the peripapillary and macular vessel density in the progression of glaucoma.

Methods

This was a observational, prospective, cross-sectional study at the department of Ophthalmology in The People’s Hospital of Leshan between January 2019 and February 2020. The research protocol was approved by the Ethics Committee of People’s Hospital of Leshan and adhered to the Declaration of Helsinki. Written informed consents were obtained from all participants. Participants of this study included normal control subjects (11 person, 20 eyes)and chronic PACG patients(105 patients, 198 eyes). According to Glaucoma Staging System, all subjects were divided into 5 groups: no glaucoma, early glaucoma, moderate glaucoma, advance glaucoma, severe glaucoma. Normal subjects had no family history of glaucoma, intraocular pressure (IOP)≤21mm Hg, open angles on gonioscopy, normal anterior and posterior segment on slit-lamp examination, no glaucomatous optic discs, no RNFL defects, and no glaucomatous VF defects. A normal VF was defined as a PSD within the 95% confidence limits and a Glaucoma VF test within normal limits. PACG patients had closed angles on gonioscopy. PACG patients had glaucomatous changes on ONH examination and VF examination, including rim narrowing, notching, RNFL defects. Glaucomatous VF defects were defined as a cluster of ≥ 3 points with P < 0.05 on the pattern deviation map in at least one hemifield, including ≥ 1 point with P < 0.01; a PSD of P < 0.05; or glaucoma VF test result outside the normal limits. Exclusion criteria were presence of any retinal or macular pathology, any media opacities, and any systemic or neurological conditions that could produce VF defects. Patients unable to perform reliable VF testing or with poor quality OCTA, including segmentation errors, were also excluded. All participants underwent a comprehensive ocular examination, which included corrected distance visual acuity measurement, slit-lampbiomicroscopy,Goldmann applanation tonometry, gonioscopy, fundus examination, stereoscopic optic disc photography.

Humphrey visual field test

VF test was performed with the Swedish Interactive Threshold Algorithm (SITA) Standard strategy program 24–2 of the Humphrey Field Analyzer 3 (Carl Zeiss Meditec, Jena, Germany). Fixation losses ≤20%, false positives, and false negatives ≤33% were established as the reliability criteria. The glaucoma stage was determined based on Glaucoma Staging System (GSS)[9]. In brief, the GSS stage assignment was based primarily on Humphrey visual field parameters. The value of MD determined the stage of severity: stage 0 (no glaucoma) was determined when MD is of more than -1.0 dB, stage 1 (early glaucoma) with MD between -1.00 dB and -5.00 dB, stage 2 (moderate glaucoma) with MD between -5.01 dB and -12.00 dB, and stage 3 (advance glaucoma) with MD is between -12.01 dB and -20Db,stage 4 (severe glaucoma) with MD is more than -20 dB.

Structural parameters and vessel density

The images of Macular and peripapillary 6x6 mm scans were acquired with SD-OCT (Cirrus, HD-OCT 5000; Carl Zeiss Meditec, Inc.) to get GCIPL thickness(calculates the GCIPL thickness measurements in 6 sectors of the macula), peripapillary RNFL thickness, Rim area, C/D ratio, MVD and PVD. OCTA scans with a signal strength > 7.Angioplex Metrix software of the Cirrus HD-OCT automatically calculates 2 parameters from the superficial retinal layer slab: vessel length density, defined as the total length of perfused vasculature per unit area in the region of measurement, and perfusion density, defined as the total area of perfused vasculature per unit area in the region of measurement. In our study, we considered vessel length density for analysis. AngioPlex™ subdivides the scan into four areas: a central circle, an inner circle, an outer circle and a full circle.

Statistical analysis

All the statistical analyzes were performed using the SPSS software version 20 (SPSS Inc, Chicago). A chi-square test was used to compare different demographic characteristics, including age, gender, history of anti-glaucomatous surgery, and use of anti-glaucomatous medications. Descriptive statistics were used to calculate mean and median of MD, PSD, RNFL,GCIPL, rim area, average C/D, PVD and MVD. Student’s t tests were used to compare the average values of measurements between normal and glaucomatous. Univariate analysis with Pearson correlation test and multivariate analysis with ANOVA testing were performed to determine the correlation between structural parameters and functional parameters, vessel density and functional parameters. Significance was taken as p < 0.05. However, for multiple comparisons among groups, a Kruskal-Wallis test with Dunn’s correction was applied with resultant significance level set at p < 0.01.

Results

Demographic characteristics of glaucoma and normal subjects

The mean of age was 61.3±19.0 for men and 63.6±14.8 for women.Compared to the normal group, MD was significantly lower with higher IOP and PSD in glaucoma group.(Table 1)

Table 1

Demographic characteristics of the study subjects.

	Normal (20 eyes, 11 patients)	Glaucoma (198 eyes, 105 patients)	PP Value
Age (y)	68.2 ± 1.2	70.1 ± 0.8	0.25 a
Gender, n (Male/Female)	8/3	68/37	0.08 b
VF
MD (dB)	-0.247 ± 0.135	-12.586 ±10.192	< 0.0001 a
PSD (dB)	1.460 ± 0.167	6.706 ± 4.039	< 0.0001 a
IOP (mmHg)	16.500 ±1.539	25.354 ±9.380	0.001 a
Topical glaucoma medication, N
0	null	55
1	null	48
>1 null	null	36
Glaucoma surgery history, N	null	72

dB = decibels; IOP = intraocular pressure; MD = mean deviation; PSD = pattern standard deviation VF = visual field.

a Statistical significance tested with Student's t test.

b Statistical significance tested with the Chi-square test.

The changes of functional parameters, structural parameters and retinal vessel density

Table 2 showed the changes of functional parameters, structural parameters and retinal vessel density among the five groups (normal, early, moderate, advance and severe group). There were significant differences in all measurements among the groups, including the functional parameters (MD and PSD), structural parameters(average, superior and inferior areas of RNFL thickness, GCIPL thickness), rim area, average C/D ratio, PVD and MVD (central, inner, outer, full areas)(p < 0.01).From Table 2, we could find that the average PVD(full area) was 18.50±0.52 mm-2(from 18.00 to 19.30 mm-2), while the average MVD (full area) was 17.75±0.44 mm-2(from 17.20 to 18.40 mm-2) in the normal group. The average PVD (full area) was 15.83±2.11 mm-2(from 12.70 to 18.00 mm-2), while the average MVD (full area) was 15.19±2.26 mm-2(from 10.60 to 17.60 mm-2) in the early group. The average PVD (full area) was 14.46±2.29 mm-2(from 10.20 to 17.80 mm-2), while the average MVD(full area) was 13.50±2.93 mm-2(from 8.20 to 17.50 mm-2) in the moderate group. The average PVD (full area) was 12.19±3.87 mm-2(from 6.00 to 17.10 mm-2), while the average MVD (full area) was 11.78±4.87 mm-2(from 3.10 to 17.30 mm-2) in the advance group. The average PVD (full area) was 10.48±3.64 mm-2(from 4.80 to 15.10 mm-2), while the average MVD (full area) was 10.89±3.46mm-2(from 3.00 to 16.10 mm-2) in the severe group.

Table 2

Results of functional parameters, structural parameters and vessel density.

Variables	Normal	Early	Moderate	Advance	Severe	P a
(group1,n = 20 eyes)	(group2,n = 70 eyes)	(group3,n = 46 eyes)	(group4,n = 31 eyes)	(group4,n = 51)	Value
Functional parameters (VF)
MD(dB)	-0.25±0.14	-2.49±1.06	-9.35±1.73	-15.31±1.82	-27.70±3.62	P<0.01
PSD(dB)	1.46±17	2.32±1.04	7.56±3.26	8.73±1.74	10.73±2.17	P<0.01
Structural parameters
Average RNFL thickness (μm)	102.75±9.77	79.26±12.23	67.89±9.06	65.87±10.51	61.94±9.54	P<0.01
Superior RNFL thickness (μm)	129.00±14.23	98.50±19.28	84.70±20.07	72.35±12.93	69.61±9.8 0	P<0.01
Inferior RNFL thickness (μm)	142.25±16.02	95.26±20.35	74.70±14.34	72.13±20.54	64.37±10.09	P<0.01
Average GCL+IPL thickness (μm)	87.75±1.83	67.43±7.93	66.91±8.69	59.52±6.57	51.88±3.64	P<0.01
Superior GCL+IPL thickness (μm)	89.00±2.18	68.07±9.88	66.39±14.93	62.35±12.34	55.84±6.19	P<0.01
Inferior GCC+IPL thickness (μm)	85.25±3.93	65.83±8.35	63.53±11.61	58.52±6.59	56.37±5.11	P<0.01
Optic disc
Rim area (mm 2)	1.30±0.25	1.17±0.44	0.81±0.21	0.75±0.33	0.43±0.12	P<0.01
Average C/D ratio	0.50±0.19	0.61±0.22	0.78±0.31	0.82±0.07	0.90±0.05	P<0.01
Macular vessel density (1/mm2)
Central	8.48±0.83	7.11±2.81	6.05±2.72	5.79±3.55	5.04±3.41	P<0.01
Inner	17.80±0.58	15.53±2.33	14.67±3.21	12.48±6.72	12.04±4.31	P<0.01
Outer	18.05±0.43	15.38±2.34	13.40±2.94	12.20±4.46	10.94±3.48	P<0.01
Full	17.75±0.44	15.19±2.26	13.50±2.93	11.78±4.87	10.89±3.46	P<0.01
peripapillary vessel density(1/mm2)
Central	1.01±1.62	4.60±4.06	3.97±5.65	1.86±3.59	0.12±0.17	P<0.01
Inner	18.15±0.92	15.47±2.10	13.49±2.26	8.73±5.05	8.20±3.33	P<0.01
Outer	19.18±0.39	16.40±2.96	15.44±2.58	13.58±3.67	11.44±4.05	P<0.01
Full	18.50±0.52	15.83±2.11	14.46±2.29	12.19±3.87	10.48±3.64	P<0.01

GCL+IPL = ganglion cell layer+inner plexiform layer; MD = mean deviation; PSD = pattern standard deviation; C/D = cup/disc; RNFL = retinal nerve fiber layer; VF = visual field.

Numbers displayed are mean ± standard deviation.

a Differences between groups were tested with Kruskal-Wallis test with Dunnett’s correction.

In the en face OCTA image of the superficial vascular complex (SVC), there are centripetally branching vessels terminating in the central foveal avascular zone (FAZ). The branching vessels were observably denser in normal eyes than those with glaucoma (Fig 1A). The changes of PVD were the same as MVD (Fig 1B). Reduced PVD and MVD in glaucoma were detected and a statistically significant correlation with glaucoma stages (Fig 1C) was appreciated. The data confirmed a correlation between retinal vessel density and glaucomatous stage. Fig 2 showed the changes of RNFL and GCIPL thickness among five groups (normal, early, moderate, advance and severe groups).The GCC is absent at the fovea, but gradually becomes thicker and reaches the thickest point at the parafoveal annulus. As expected, the rim area had significantly with higher C/D area ratios in glaucomatous eyes corresponding to the severity of disease (Fig 2A). Reduced RNFL thickness and GCIPL thickness were detected and with a statistical relation to the stage of glaucoma, which is in agreement with the traditional diagnosis of glaucoma.(Fig 2B).

Fig 1

The changes of peripapillary and vascular perfusion in different stages of glaucoma.

A. These are macular vascular images of 6 x6 mm en face angiograms generated by OCTA. Images in the first column are AngioPlex-superficial maps. The second column are the corresponding OCT sections of retina. From the images, we can see that a significant reduction of MVD in glaucoma eyes compared to normal eyes. B. These are peripapillary vascular images of 6 x6 mm en face angiograms generated by OCTA. Images in the first column are AngioPlex-ONH maps. The second column are the corresponding OCT sections of ONH From the images, we can see that a significant reduction of PVD in glaucoma eyes compared to normal eyes. C. The bar graphs demonstrate that the reduced MVD and PVD are strongly related to the severity of glaucoma, the more severe the glaucoma was, the lower PVD and MVD were.

Fig 2

The changes of RNFL, GCIPL thickness and VF in different stages of glaucoma.

A. Combined GCA and RNFL deviation maps are in the first column, the maps of RNFL thickness are in the second column, GCIPL are in the third column, the corresponding VF maps are in the fourth column. From the maps, we can see that a significant reduction of RNFL and GCIPL thickness. B. The bar graphs demonstrate that the reduced RNFL and GCIPL thickness are strongly related to the severity of glaucoma, the more severe the glaucoma was, the thinner RNFL and GCIPL thickness were.

Correlation of retinal vessel density with structural and functional tests

Table 3 highlighted the correlation of retinal vessel density with structural and functional parameters in glaucomatous eyes.PVD (central, inner, outer, full) and MVD (central, inner, outer, full) showed a strong positive correlation with MD and rim area, while negatively correlated with PSD and average C/D ratio (P≤0.01). Perpapillary vessel density(central, inner, outer, full) were positively correlated with GCIPL and RNFL thickness(average, superior, inferior)(p≤0.01). MVD (central, inner, outer, full) were positively correlated with GCIPL thickness (average, superior, inferior).There was no correlation between the MVD and RNFL thickness in the central(r = -0.039 p = 0.583) and inner (r = 0.08 p = 0.916)areas of the macula.

Table 3

The correlation of retinal vessel density with structural and functional tests in glaucomatous eyes.

Glaucoma (n = 198)
	Central	inner	outer	full	central	inner	outer	full
VF
MD(dB)	r = 0.303**	r = 0.685**	r = 0.506**	r = 0.586**	r = 0231***	r = 0.281**	r = 0.436**	r = 0.442 **
PSD(dB)	r = -2.53**	r = -0.525**	r = -0.367**	r = -4.40**	r = -1.23**	r = -1.62*	r = -0.288**	r = -0.267**
Disc
Rim area	r = 0.647**	r = 0.569**	r = 0.192**	r = 0.322**	r = 0.321**	r = 0.184**	r = 0.469**	r = 0.407**
Average C/D ratio	r = -0.559**	r = -0.524**	r = -0.288**	r = -0.228***	r = -0.244**	r = -0.193**	r = -0.408**	r = -0.365**
Structural parameters
Average GCIPL thickness(um)	r = 0.174**	r = 0.664**	r = 0.599**	r = 0.655**	r = 0.294**	r = 0.429**	r = 0.537**	r = 0.533**
Superior GCIPL thickness(um)	r = 0.177**	r = 0.513**	r = 0.426**	r = 0.463**	r = 0.295**	r = 0.337**	r = 0.419**1	r = 0.418**
Inferior GCIPL thickness(um)	r = 0.182**	r = 0.419**	r = 0.422**	r = 0.458**	r = 0.232***	r = 0.303**	r = 0.428**	r = 0.407**
Average RNFL thickness (μm)	r = 0.524**	r = 0.412**	r = 0.287**	r = 0.197**	r = -0.039	r = 0.080	r = 0.271**	r = 0.225***
Superior RNFL thickness(um)	r = 0.361**	r = 0.541**	r = 0.282**	r = 0.382**	r = -0.030	r = 0.175*	r = 0.313**	r = 0.294**
Inferior RNFL thickness(um)	r = 0.514**	r = 0.372**	r = 0.284 **	r = 0.186**	r = -0.027	r = -0.038	r = 0.266**	r = 0.204**

RNFL = retinal nerve fiber layer; GCIPLC = ganglion cell-inner plexiform layer complex. MD = mean deviation; PSD = pattern standard deviation; C/D = cup/disc; RNFL = retinal nerve fiber layer; VF = visual field.

Correlation between parameters was tested with Pearson correlation test.

*P<0.05

**P≤0.01

***P≤0.001.

Discussion

Prior studies have shown that glaucomatous damage can be detected by OCT as reduced RNFL thickness in the peripapillary region or thinning of the ganglion cell complex within the macula area[10-11].With the development of OCTA, which now can provides us with qualitative and quantitative information of various retinal regions.

In our study, we also proved that the reduced PVD and MVD are significantly correspond with the severity of VF damage along the glaucoma severity stages, regardless of the state of anterior chamber angle, which was agreement with some prior researches [12-15].We also found that reduced RNFL thickness and GCIPL thickness were detected and with a statistical relation to the stage of glaucoma, which is agree with the traditional diagnosis standard of glaucoma. In the initial phase of glaucoma, functional damage might be undetectable with VF testing, but the structural damage had been detected, with a loss of retinal ganglion cells. Some studies had shown the structure-function relationships between various glaucoma parameters and severity in visual field testing [16-17].

Additionally, we had shown the positive correlation of PVD and MVD with MD and rim area, while negatively correlated with PSD and average C/D ratio, which means the more severe the glaucoma was, the lower PVD and MVD were. Wu et al [18] consider reduced MVD occurs in POAG despite of age-related changes, which also correlates with reductions in RNFL and GCC measurements. In our study, Table 3 showed that PVD(central, inner, outer, full) were positively correlated with GCIPL and RNFL thickness(average, superior, inferior).MVD (central, inner, outer, full) were positively correlated with GCIPL (average, superior, inferior), but with no correlation to the RNFL thickness in the central and inner area of macula. Manalastas et al [19] consider that the weaker association of MVD compared with ONH vessel density with tissue thickness may be due to differences in micorovasculature between the macula and ONH. It is well documented that GC is absent at the fovea of macular, then gradually becomes thicker and reaches the thickest point at the parafoveal annulus, which may explain why MVD in the central and inner area of macula has no correlation with RNFL.

Rao et al [20] suggested that structural changes in PACG occurred earlier than the reduction in retinal vessel density. But, Richter et al [21] considered that OCTA parameters had stronger associations with functional rather than structural measures of glaucoma. It has long been debated whether reduced blood perfusion in glaucomatous eyes is secondary to loss of ganglion cells or reduce of RNFL thickness, but we consider that the glaucoma affects the RGC density in the macula, and the decreased blood supply at the affected area could be the result or consequence of glaucomatous damage. This hypothesis is still worthy of long-term research.

Compared to traditional glaucoma staging system judged by VF, the results of PVD and MVD might be a new glaucoma staging system judged by OCTA. In our study, we attempted to categorize the stage of glaucoma according the average value of MVD and PVD: stage 0 (no glaucoma) was determined when PVD was of more than 18.50 mm-2 or MVD was of more than 17.75 mm-2; stage 1 (early glaucoma) with PVD between 15.83 and 18.50 mm-2 or MVD between 15.19 and 17.75 mm-2; stage 2 (moderate glaucoma) with PVD between 14.46 and 15.83 mm-2or MVD between 13.50 and 15.19 mm-2; stage 3 (advance glaucoma) with PVD between 12.19 and 14.46 mm-2or MVD between 11.78 and 13.50 mm-2;stage 4 (severe glaucoma) with PVD is less than 12.19 mm-2or MVD is less than 11.78 mm-2. Of course, this new staging system was based on the average value of MVD and PVD in full area, we still need much more data to support the staging standard or more rational approach to categorize the stage of glaucoma.

There were still some limitations to our study. Firstly, we were planned to recruit more glaucoma subjects but ignored that a smaller number of normal participants were recruited than glaucoma as whole, and therefore there is a potential bias in interpretation. Besides, longitudinal and reproducible study will be required to provide more information of how retinal vessel density and structural changes in glaucoma progression with OCTA.

In summary, the changes of PVD and MVD had strongly positive correlation with GCIPL thickness and RNFL thickness, while had negative correlation with the severity of glaucoma, which meant the more severe the glaucoma was, the lower PVD and MVD were. According to the results of PVD and MVD, we may attempt to grade the staging of glaucoma by OCTA. We suggested that the changes of PVD and MVD might be better facilitated in detecting and monitoring the progression of glaucoma.

(SAV)

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16 Mar 2020

PONE-D-20-04584

Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography

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5. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: No

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This study demonstrates the relationship between retinal vessel density (peripapillary vessel density, PVD and macular vessel density, MVD) and glaucomatous parameters (mean deviation(MD),pattern standard deviation(PSD), retinal nerve fiber layer (RNFL), ganglion cell inner plexiform layer (GCIPL),rim area, average cup/disc(C/D) ratio).

Abstract:

Purpose:

1. Line 29: what do you mean by administrative abilities?

Results:

Line 45: “Reduced peripapillary and macular vessel density in glaucoma was

1. 46 detected and a statistically significant correlation with glaucoma stages (P<0.01).”

correction: were

Conclusion:

1. Line 51-55: need English grammar correction, I will reword the conclusion

Introduction:

1. Line 63: “As all we known” you mean as all we know?

2. Line 67: as all we know

3. Line 76: “With the recently development of OCTA”

Recent development

4. Line 78: “we can easily to get insight”

Please remove “to”

Methods:

1. Line 105: how did the patient present to your clinic? Acute vs chronic PACG? Did you see changes in retinal vessel density (peripapillary vessel densityand macular vessel density) in patient with acute angle closure.

2. How many image did you take for each patient at every visit, how many operators? Did you check for repeatability and reproducibility for image quality control?

Result:

1. Line 156: you can mention the mean of age for men and women, and remove “we could see that there was no statistically significant difference between normal and glaucoma groups for age and gender”

2. Line 161: Table 2 : can you please align all numbers in table 2? For example, each column should start at a certain point and all numbers in this column should start at same point and use separate cells. Here is the journal guidelines for table: https://journals.plos.org/plosone/s/tables .

3. Line 184: “The data suggested correspondence” I believe you mean correlation.

4. Line 194: Table 3 : same for table 2.

Reviewer #2: Is the manuscript presented in an intelligible fashion and written in standard English?

Line 47: I would remove "As" and being the sentence with "In addition"

Line 52: I would replace "while" with "and"

Line 54: I would replace "suggested" with "postulate" or "theorize"

Line 54: I would replace "might" with "may"

Line 55: "facilitated" should be changed to "facilitate"

Line 63: Change "were damaged" to "suffer from"

Line 63: Change "As we all known" to "It is well documented that"

Line 64: Change "monitor" to "monitoring"

Line 65: I would change "visual" to "vision"

Line 67: Change "all known" to "know"

Line 68: Change "is" to "occurs"

Line 68: Remove "some customs"

Line 69: Change "standard" to "standards"

Line 70: End the Glaucoma with a period and not a comma

Line 71: Change "had been" to "is"

Line 73: Change "Reducing" to "reduction"

Line 75: Remove "in the disease"

Line 77: Remove "various of" and change sentence to "in various retinal regions"

Line 78: Change "to get" to "obtain"

Line 79: remove "so"

Line 83: change "also had" to "has"

Line 84: Change "and correlates" to "correlating"

Line 84: Replace "But these researches" to "These studies however"

Line 85 and 86: I would replace "Because of the anatomy various, the number" to "Due to anatomical variations, the prevalence"

Line 86: Change "are much more" to "is greater"

Line 88: I would add the word "and" in between "PACG" and "to evaluate"

Line 92: I would change "study at department" to "study at the department"

Line 112: I would change "reliably" to "reliable"

Line 123: I would add the word "was" before "based" and replace "decide" with "determined"

Line 124: I would replace "severe" with "severity"

Line 138: I would replace "to analyze" with "for analysis"

Line 156: I would replace "we could see" with "demonstrates"

Line 157: I would change "Compared to normal group" to "Compared to the normal group"

Line 184: I would add "was appreciated" after (figure 1c)

Line 188: I would replace "was" with "had"

Line 191: I would replace "agree" with "in agreement"

Line 194: Replace "showed" with "highlighted"

Line 196: Replace "were strongly positively correlated" "showed a strong positive correlation"

Line 202: Replace "area of macular" with "areas of the macula"

The sentence benign at line 230 to line 234 is not very clear and I would advise restricting/rewording

Please reword the sentence starting at Line 242

Additional comments:

1) Could you explain why 20 eyes rather than 22 eyes were used for the 11 normal subjects and why 198 eyes rather than 210 eyes were sued for the 105 PACG patients?

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Mike Zein, MD

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

24 Mar 2020

Dear editor and reviewers:

It is with excitement that I resubmit to you a revised version of manuscript “Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography” for the "PLOS ONE ". Thank you for your guidance in revising my manuscript and giving me the opportunity to resubmit this manuscript. We are sending the revised manuscript according to the comments of the reviewers. Revised portion are rectified in red in “Revised Manuscript with Track Changes”. We have responded specifically to each suggestion below, beginning with your own. To make the changes easier to identify where necessary, I have numbered them.

Journal Requirements:

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming.

Response:

As suggested by editor, I have rectified my manuscript to meet “PLOS ONE’s style requirements in revised manuscript.

2. We noticed you have some minor occurrence of overlapping text with the following previous publication(s), which needs to be addressed.

Response:

As suggested by editor, I have rewritten some parts of my manuscript and cited all sources might be duplicated text in my revised manuscript.

3. We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly.

Response:

I’m pleasure to share my data referred to this manuscript, I have uploaded the data as supporting information files to replicate my study findings.

4. We note that you have provided funding information that is not currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form.

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement.

Response:

As suggested by editor, I have removed any funding-related text from the manuscript and updated my Finding statement.

5. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager.

Response:

As suggested by editor, I have updated my ORCID ID information.

Review Comments to the Author

Reviewer #1:

1. Abstract:

Purpose:

1). Line 29: what do you mean by administrative abilities?

Response:

Following the suggestion of the reviewer, I have replaced “administrative” with “monitoring”( Line 29,Page 2)

Results:

2)Line 45-46: “Reduced peripapillary and macular vessel density in glaucoma was detected and a statistically significant correlation with glaucoma stages (P<0.01).” correction: were

Response:

Following the suggestion of the reviewer, I have corrected the mistake. (Line 46, page 2) .

Conclusion:

3). Line 51-55: need English grammar correction, I will reword the conclusion

Response”

Following the suggestion of the reviewer, I have rewritten the conclusion. (Line 56-62, Page 3)

2. Introduction:

1). Line 63: “As all we known” you mean as all we know?

Response:

Following the suggestion of the reviewer, I have corrected the mistake. (Line 70-71, Page 3)

2). Line 67: as all we know

Response:

Following the suggestion of reviewer, I have corrected the grammar mistake. (Line 76, Page 3)

3). Line 76: “With the recently development of OCTA” Recent development

Response:

Following the suggestion of reviewer, I have corrected the grammar mistake.(Line 86, Page 4)

4). Line 78: “we can easily to get insight” Please remove “to”

Response:

Following the suggestion of reviewer, I have corrected the grammar mistake.(Line 89, Page 4)

3. Methods:

1) Line 105: how did the patient present to your clinic? Acute vs chronic PACG? Did you see changes in retinal vessel density (peripapillary vessel densityand macular vessel density) in patient with acute angle closure.

Response:

Most patients complained of blurred vision, but when we found increased intraocular pressure and changes in optic disc, we will conduct further examination for these suspected glaucoma patients. In this manuscript, all cases were chronic PACG. Acute angle-closure glaucoma is usually accompanied by corneal edema, which makes it difficult to obtain clear OCTA images. Therefore, we did not observe the changes of OCTA in patients with acute angle-closure.

2). How many images did you take for each patient at every visit, how many operators? Did you check for repeatability and reproducibility for image quality control?

Response:

We have two operators, one is responsible for OCTA scanning, the other one is responsible for VF examination. In order to get best quality images, we usually take 3 OCTA images for macular and 3 for optic disc for each patient at every visit. I am responsible for checking the repeatability and reproducibility for all images. The best one was selected for statistical analysis.

4. Result:

. 1) Line 156: you can mention the mean of age for men and women, and remove “we could see that there was no statistically significant difference between normal and glaucoma groups for age and gender”

Response:

Following the suggestion of the reviewer, I have made some changes in my revised manuscript.(Line 169, Page 6)

2) Line 161: Table 2 : can you please align all numbers in table 2? For example, each column should start at a certain point and all numbers in this column should start at same point and use separate cells. Here is the journal guidelines for table: https://journals.plos.org/plosone/s/tables .

Response:

Following the suggestion of the reviewer, I have aligned all numbers in table 2.

3). Line 184: “The data suggested correspondence” I believe you mean correlation.

Response:

Following the suggestion of the reviewer, I have made some modifications to this sentence.(Line 199, Page 7)

4). Line 194: Table 3 : same for table 2.

Response:

Following the suggestion of the reviewer, I have made some modifications to table 3.

Reviewer #2:

1) Line 47: I would remove "As" and being the sentence with "In addition"

Response:

Following the suggestion of reviewer, I have removed “As” and being the sentence with “In addition”.(Line 47, Page 2)

2) Line 52: I would replace "while" with "and"

Response:

Following the suggestion of reviewer, I have replaced “while” with “and”.(Line 56, Page 3)

3) Line 54: I would replace "suggested" with "postulate" or "theorize"

Response:

Following the suggestion of reviewer, I have replaced “suggested ” with “theorize ”.( Line 61, Page 3)

4) Line 54: I would replace "might" with "may"

Response:

Following the suggestion of reviewer, I have replaced “might ” with “may ”.(Line 61, Page 3)

5) Line 55: "facilitated" should be changed to "facilitate"

Response:

Following the suggestion of reviewer, I have changed “facilitated” to “facilitate”.

6) Line 63: Change "were damaged" to "suffer from"

Response:

Following the suggestion of reviewer, I have changed “were damaged” to “suffer from”.(Line 70, Page 3)

7) Line 63: Change "As we all known" to "It is well documented that"

Response:

Following the suggestion of reviewer, I have changed “As we all known” to “It is well documented that”. (Line 70-71, Page 3)

8) Line 64: Change "monitor" to "monitoring"

Response:

Following the suggestion of reviewer, I have changed “monitor” to “monitoring”.(Line 71, Page 3)

9 ) Line 65: I would change "visual" to "vision"

Response:

Following the suggestion of reviewer, I have changed “visual” to “vision”.(Line 72, Page 3)

10) Line 67: Change "all known" to "know"

Response:

Following the suggestion of reviewer, I have changed “all known” to “know”. (Line 76, Page 3)

11) Line 68: Change "is" to "occurs"

Response:

Following the suggestion of reviewer, I have changed “is” to “occurs”. (Line 77, Page 3)

12) Line 68: Remove "some customs"

Response:

Following the suggestion of reviewer, I have removed “some customs”.(Line 77, Page 3)

13) Line 69: Change "standard" to "standards"

Response:

Following the suggestion of reviewer, I have changed “standard” to “standards”.(Line 78, Page 3)

14) Line 70: End the Glaucoma with a period and not a comma

Response:

Following the suggestion of reviewer, I have changed comma to period. (Line 79, Page 3)

15) Line 71: Change "had been" to "is"

Response:

Following the suggestion of reviewer, I have changed “had been” to “is”.(Line 80, Page 3)

16) Line 73: Change "Reducing" to "reduction"

Response:

Following the suggestion of reviewer, I have changed “Reducing” to “reduction”(Line 82, Page 3)

17) Line 75: Remove "in the disease"

Response:

Following the suggestion of reviewer, I have removed “in the disease”.(Line 84-85, Page 3)

18) Line 77: Remove "various of" and change sentence to "in various retinal regions"

Response:

Following the suggestion of reviewer, I have removed “various of “and changed sentence to “in various retinal regions”. (Line 87, Page 4)

19) Line 78: Change "to get" to "obtain"

Response:

Following the suggestion of reviewer, I have changed “to get” to “obtain”. (Line 89, Page 4)

20) Line 79: remove "so"

Response:

Following the suggestion of reviewer, I have removed “so”.(Line 90, Page 4)

21) Line 83: change "also had" to "has".

Response:

Following the suggestion of reviewer, I have changed “also had” to “has”. (Line 93, Page 4)

22) Line 84: Change "and correlates" to "correlating”.

Response:

Following the suggestion of reviewer, I have changed “and correlates” to “correlating”.(Line 94, Page 4)

23) Line 84: Replace “But these researches” to “These studies however ".

Response:

Following the suggestion of reviewer, I have replaced “But these researches” to “These studies however ".(Line 95 ,Page 4)

24) Line 85 and 86: I would replace "Because of the anatomy various, the number" to "Due to anatomical variations, the prevalence"

Response:

Following the suggestion of reviewer, I have replaced Because of the anatomy various, the number" to "Due to anatomical variations, the prevalence".(Line 97, Page 4)

25) Line 86: Change "are much more" to "is greater"

Response:

Following the suggestion of reviewer, I have changed "are much more" to "is greater" (Line 98, Page 4)

26) Line 88: I would add the word "and" in between "PACG" and "to evaluate".

Response:

Following the suggestion of reviewer, I have added the word "and" in between "PACG" and "to evaluate". (Line 99, Page 4)

27) Line 92: I would change "study at department" to "study at the department"

Response:

Following the suggestion of reviewer, I have changed "study at department" to "study at the department". (Line 103, Page 4)

28) Line 112: I would change "reliably" to "reliable"

Response:

Following the suggestion of reviewer, I have changed "reliably" to "reliable".(Line 123, Page 5)

29) Line 123: I would add the word "was" before "based" and replace "decide" with "determined".

Response:

Following the suggestion of reviewer, I have added the word "was" before "based" and replaced "decide" with "determined". (Line 135-136, Page 5)

30) Line 124: I would replace "severe" with "severity".

Response:

Following the suggestion of reviewer, I have replaced "severe" with "severity". (Line 136, Page 5)

31) Line 138: I would replace "to analyze" with "for analysis"

Response:

Following the suggestion of reviewer, I have replaced "to analyze" with "for analysis". (Line 151, Page 6)

32) Line 156: I would replace "we could see" with "demonstrates".

Response:

Following the suggestion of reviewer 1#, I have made some changed to this paragraph. (Line 169-171, Page 6)

33) Line 157: I would change "Compared to normal group" to "Compared to the normal group".

Response:

Following the suggestion of reviewer, I have changed "Compared to normal group" to "Compared to the normal group". (Line 170, Page 6)

34) Line 184: I would add "was appreciated" after (figure 1c)

Response:

Following the suggestion of reviewer, I have added "was appreciated" after (figure 1c) ( Line 197, Page 6)

35) Line 188: I would replace "was" with "had".

Response:

Following the suggestion of reviewer, I have replaced "was" with "had". (Line 203, Page 6)

36) Line 191: I would replace "agree" with "in agreement".

Response:

Following the suggestion of reviewer, I have replaced "agree" with "in agreement". (Line 206, Page 7)

37) Line 194: Replace "showed" with "highlighted".

Response:

Following the suggestion of reviewer, I have replaced "showed" with "highlighted". (Line 209, Page 8)

38) Line 196: Replace "were strongly positively correlated" "showed a strong positive correlation"

Response:

Following the suggestion of reviewer, I have replaced "were strongly positively correlated" with "showed a strong positive correlation". (Line 211-212, Page 8)

39) Line 202: Replace "area of macular" with "areas of the macula".

Response:

Following the suggestion of reviewer, I have replaced "area of macular" with "areas of the macula". (Line 218, Page 8)

40) The sentence benign at line 230 to line 234 is not very clear and I would advise restricting/rewording.

Response:

Following the suggestion of reviewer, I have reworded the sentence.(Line 250-253, Page 9)

41) Please reword the sentence starting at Line 242

Response:

Following the suggestion of reviewer, I have reworded the sentence.(Line 262, Page 9)

Additional comments:

Could you explain why 20 eyes rather than 22 eyes were used for the 11 normal subjects and why 198 eyes rather than 210 eyes were sued for the 105 PACG patients?

Response:

Our exclusion criteria were presence of any retinal or macular pathology, any media opacities, and any systemic or neurological conditions that could induce unreliable VF testing or poor quality OCTA images. So, some of our subjects had only one eye that met our inclusion criteria for statistical analysis.

Thanks for the help of reviewers and editor, I hope that the revised manuscript is now suitable for publication. Certainly, we are pleased to get more advice from you.

Best wish.

Li Zhen

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

18 May 2020

PONE-D-20-04584R1

Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography

PLOS ONE

Dear Dr. Li,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

A learned reviewer has suggested a few minor revision that can be incorporated during this manuscript revision.

We would appreciate receiving your revised manuscript by Jul 02 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Sanjoy Bhattacharya

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: The content of this manuscript is now sound and fine, though not particularly novel findings. There are a lot of formatting issues. For example, there are non-English characters present in the figures. And also, other font is used among Times New Roman in the main text, which looks messy. Systematic language and formatting editing are needed before being published. Lastly, age typically only needs one digit after the decimal point and correlation only needs two digits after the decimal.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: Yes: Mike Zein, MD

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

21 May 2020

Dear editor and reviewers:

It is with excitement that I resubmit to you a revised version of manuscript “Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography” for the "PLOS ONE ". Thank you for your guidance in revising my manuscript and giving me the opportunity to resubmit this manuscript. We are sending the revised manuscript according to the comments of the reviewers. Revised portion are rectified in red in “Revised Manuscript with Track Changes”. As suggested by Reviewer #3, I have made some changes to my figures and tables (Figure 1c, Figure 2b and Table 3), ages have been changed to remain one digit after the decimal point. After I referred the expression of correlation in many references, I found that Pearson’s correlation coefficients were usually kept three digits after the decimal, so, I did not change anymore. In order to looks more clarity, I did some format changes in Table 3.

Thanks for the help of reviewers and editor, I hope that the revised manuscript is now suitable for publication. Certainly, we are pleased to get more advice from you.

Best wish.

Li Zhen

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

3 Jun 2020

Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography

PONE-D-20-04584R2

Dear Dr. Li,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Sanjoy Bhattacharya

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #2: Yes

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #2: (No Response)

Reviewer #3: My concerns are addressed. Note that, before the emergence of OCTA, there are some research which have investigated if and how glaucoma is related to major retinal vessel locations. See the following and please cite these works in the Introduction:

Baniasadi, N., Wang, M., Wang, H., Mahd, M. and Elze, T., 2017. Associations between optic nerve head–related anatomical parameters and refractive error over the full range of glaucoma severity. Translational vision science & technology, 6(4), pp.9-9.

Radcliffe, N.M., Smith, S.D., Syed, Z.A., Park, S.C., Ehrlich, J.R., De Moraes, C.G., Liebmann, J.M. and Ritch, R., 2014. Retinal blood vessel positional shifts and glaucoma progression. Ophthalmology, 121(4), pp.842-848.

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Reviewer #2: Yes: Mike Zein, MD

Reviewer #3: No

5 Jun 2020

PONE-D-20-04584R2

Comparisons of retinal vessel density and glaucomatous parameters in optical coherence tomography angiography

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