Dr.Jayasree P V, J14295, Dr. Rajesh S Kumar, Dr.Abhijit Sinha Roy, Ms. Neha Anegondi
Jayasree PV1, Rajesh S Kumar1, AbhijitSinha Roy2,Neha anegondi2
1Narayana Nethralaya Eye Hospital, Bangalore, India;2Imaging, Biomechanics and Mathematic Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
Financial disclosure: None
Corresponding Author:Prof Rajesh S Kumar, Glaucoma services, Narayana Nethralaya, E-mail: firstname.lastname@example.org
Purpose:To assess the correlation of vessel density on OCT angiography with visual fields.
Methods: In this cross sectional observational study, subjects underwent disc evaluation, visual fields (Humphrey, Zeiss), Optical Coherence Tomography(OCT) ), and assessment of
Retinal Peripapillary Capillary (RPC) vessel density with OCT angiography using AngioVue Correlation between the visual field indices and vessel density were determined by coefficient of determination, linear regression & ANOVA.
Results:45eyes were enrolled; 32eyes were glaucomatous, while the rest were normal. Vessel density shows good negative correlation with mean deviation(R2=0.5561,p<0.001), and pattern standard deviation(R2=0.3699,p<0.001).Good negative correlation of superior vessel density with inferior field loss(R2=0.433,p<0.001), and inferior vessel density with superior field loss(R2=0.5204,p<0.001) seen.
Conclusions:The structure in terms of vessel density appears to correlate with function in terms of visual fields in glaucomatous eyes.
Glaucoma is a progressive optic neuropathy in which structural changes to the optic nerve head & peripapillary retina are associated with characteristic visual field defects(1).Although elevated Intra ocular pressure is the major risk factor for ganglion cell death(2), reduced vascular perfusion also plays a significant role in the pathogenesis of glaucoma(3).Optical Coherence Tomography Angiography (OCTA) with split spectrum amplitude-decorrelation angiography (SSADA) algorithm is a recent non-invasive technique to image the Optic nerve head (ONH) vasculature in vivo(4).This study aims to assess the correlation of Vessel density on OCT angiography with visual fields by HFA.
This was a prospective, cross sectional observational study conducted at tertiary eye care centre in south India. The Institute’s Ethics Committee approved the study; informed consent obtained from all participants.
Age ≥18 years, corrected distance visual acuity of 20/40 or better, refractive error within ±5 D sphere and ±3 D cylinder were the inclusion criteria.
Subjects who had media opacities, which affected the quality of tests, or any ocular or neurological disease other than glaucoma, which could confound the evaluation, were excluded.
All subjects underwent a comprehensive ocular examination, including a detailed medical history, best corrected visual acuity measurement, slit-lamp biomicroscopy, Goldmann
applanation tonometry,4 mirror gonioscopy, dilated fundus examination, visual field (VF) examination and OCT imaging with RTVue-XR SD-OCT (Optovue Inc., Fremont, CA).
Humphrey Field analyzer II, model 720i, with SITA standard 24-2 program was used to perform VF examination.Fixation losses less than 20%, false positive and false negative response rates less than 15% indicated a reliable fields test. The mean deviation and pattern standard deviation were used as the global sensitivity index.
OCTA image from the radial peripapillary capillaries (RPC) layer of ONH was used for analysis.Percentage area occupied by vesselsgives the Vessel density.
Figure 1:shows the OCTA image and visual fields in a normal eye, glaucomatous eye with focal defects and glaucomatous eye with diffuse defects.
Correlation between various parameters of visual fields with vessel density were analysed with coefficient of determination.Linearregressionwas performedbetween vessel density, Mean Deviation(MD) and Pattern Standard Deviation(PSD), inferior vessel density with superior visual field and superior vessel density with inferior visual field. ANOVAwas performed between normal and glaucomatous eyes.
45eyes were enrolled for the study; 32eyes were glaucomatous, while the rest 13 eyes were normal. 43.75 %(14 eyes) had primary open angle glaucoma and 56.25% (18 eyes) had primary angle closure glaucoma. The mean age of normal subjects was 65.38 years and that of glaucoma subjects was65.59 years.
Vessel density shows good negative correlation with mean deviation(R2=0.5561,p<0.001), and pattern standard deviation(R2=0.3699,p<0.001).
Figure 2 a.shows the relationship of vessel density with MD using linear regression.
Figure 2 b. shows the relationship of vessel density with PSDusing linear regression.
Also superior vessel density had a good negative correlation with inferior field loss(R2=0.433,p<0.001), and inferior vessel density had a good negative correlation with superior field loss(R2=0.5204,p<0.001).
Figure 3.shows the regional relationship of vessel density with visual field loss.
In glaucomatous eyes, the flow index and vessel density were noted to be reduced in recent studies, which was also seen in this study(5,6). A study had shown significant correlation of vessel density with MD &PSD(5) as was noted in this study. Another study on peripapillary OCTA in glaucoma showed correlation between inferior field defects and superior vessel density and vice versa, similar results were also seen in this study (6).
Vessel density appears to correlate with visual fields.
1)Gupta N, Weinreb RN. New definitions of glaucoma.CurrOpinOphthalmol. 1997;8:38–41.
2)Weinreb RN, Aung T, Medeiros FA. The pathophysiology and treatment of glaucoma: a review. JAMA 2014;311:1901-11.
3) Harris A. RechtmanE.Siesky B. et al. The role of optic nerve blood flow in the pathogenesis of glaucoma.OphthalmolClin North Am 2005;18:345-53.
4) Jia Y, Tan O, Tokayer J, et al. Split-spectrum amplitude-decorrelation angiography with optical coherence tomography. Opt Express 2012;20:4710-25.
5)Wang X, Jiang C, Ko T, et al. Correlation between optic disc perfusion and glaucomatous severity in patients with open-angle glaucoma: an optical coherence tomography angiography study. Graefes Arch ClinExpOphthalmol 2015; 253:157-64.
6) Liu L, Jia Y, Takusagawa HL, et al.Optical coherence tomography angiography of the peripapillary retina in glaucoma.JAMAophthalmol 2015;133:1045-52.