Choroidal structural analysis and vascularity index in retinal dystrophies

Sodi A., Lenzetti C., Murro V., Caporossi O., Mucciolo D.P., Bacherini D., Cipollini F., Passerini I., Virgili G., Rizzo S.

Purpose: To evaluate choroidal thickness (CT) in retinitis pigmentosa (RP) using enhanced depth imaging (EDI) optical coherence tomography (OCT). Methods: A retrospective analysis of a group of patients with RP who underwent EDI-OCT was performed. Choroidal thickness measurements were compared with those of age- and sex-matched healthy subjects. In the RP group, the possible association between subfoveal CT and some clinical parameters (visual acuity, age, age at disease onset, duration of the disease, macular thickness, visual field loss, electroretinography [ERG]) was evaluated. Results: The study recruited 39 patients with RP with an average age of 43.3 ± 11.3 years while the control group consisted of 73 healthy subjects with an average age of 42.9 ± 12.10 years. On average, CT was significantly thinner in the RP group compared to the controls (p<0.0001). In the RP group, we could not find any significant association between CT and the considered clinical parameters even if there was a trend for decreasing CT with increasing age (r = −0.23, p = 0.096). In the control group, subfoveal CT showed a slightly significant correlation with age (r = −0.21, p = 0.04) but not with macular thickness and visual acuity. Conclusions: In our series, CT was significantly lower in the RP group in comparison with the controls, as measured by EDI-OCT, but did not correlate with age, age at onset, duration of the disease, macular thickness, visual acuity, visual field loss, or ERG responses. Although the clinical implications of choroidal changes in RP have not yet been clearly determined, the evaluation of choroidal features may provide information that could be useful to clarify the pathophysiology of the disease.

Agrawal R., Wei X., Goud A., Vupparaboina K.K., Jana S., Chhablani J.

Recently, choroidal vascularity index (CVI) is proposed as a novel tool to evaluate the choroidal vasculature. In this study, we investigate the impact of scanning area on CVI measurement using spectral-domain optical coherence tomography (SD-OCT).Spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging mode was performed in 30 eyes from 15 normal subjects. Three scanning areas were compared: dingle foveal scan; central macular scans [scan passing through central 1000 microns circle on Early Treatment Diabetic Retinopathy Study (ETDRS) grid, inner circle]; and total macular cube scans. Binarization of OCT B-scans and segmentation of the binarized choroid layer were achieved using a previously reported validated automated software. Choroidal vascularity index (CVI) percentage was calculated. Degree of agreement among foveal, central macular and total macular CVI was assessed using intraclass correlation coefficient (ICC) and was plotted using Bland-Altman plot.The mean CVI in subfoveal, central macular and total macular scans was 49.95 ± 4.84%, 50.00 ± 4.68% and 51.10 ± 4.63%, respectively. Intraclass correlation coefficient (ICC) was more than 0.8 for all three comparisons [subfoveal versus central macular CVI, ICC = 0.92 (95% CI: 0.84-0.96); central macular versus total macular CVI, ICC = 0.90 (95% CI: 0.82-0.96); subfoveal versus total macular CVI, ICC = 0.92 (95% CI: 0.85-0.95)]. No significant differences in variance (all p > 0.05) were noted among CVI measured from the three scanning areas.Choroidal vascularity index (CVI) measurements were highly reproducible using subfoveal, central and total macular scans in healthy individuals. Single foveal scan choroidal vascularity represents total macular choroidal vascularity in healthy population.

Koh L.H., Agrawal R., Khandelwal N., Sai Charan L., Chhablani J.

To assess the choroidal vascular changes using choroidal vascularity index (CVI) in patients with age-related macular degeneration (AMD) compared to controls.Enhanced depth imaging (EDI) optical coherence tomography (OCT) scans of 64 patients with unilateral or bilateral AMD were obtained. Images with a poorly demarcated choroidal-scleral interface (CSI) were excluded from the analysis. Foveal scans of 63 AMD eyes and 35 'normal fellow' eyes were analysed. Images of 30 eyes from 18 age-matched healthy subjects were included as controls. Choroidal vascularity index (CVI) was derived from binarization of EDI OCT images, using fiji software.The mean age was 56.50 ± 5.50 years for AMD patients and 52.25 ± 6.75 years for controls. All patients were treatment naïve. Subfoveal choroidal thickness (SFCT) in AMD, 'normal fellow' eyes and controls was 314.02 ± 78.80 μm, 300.88 ± 53.85 μm and 278.5 ± 65.31 μm, respectively. Choroidal vascularity index (CVI) in AMD, 'normal fellow' eyes and controls was 64.04 ± 2.43%, 64.66 ± 2.25% and 66.07 ± 1.72%, respectively. Choroidal vascularity index (CVI) of both AMD and 'normal fellow' eyes was significantly lower compared to controls (p < 0.0001 and p = 0.007). The SFCT of AMD eye was not found to be significantly different from 'normal fellow eyes' (p = 0.45).There was no statistical difference in SFCT, but CVI was significantly lower in patients with AMD. Choroidal vascularity index (CVI) was also lower in 'normal fellow' AMD eyes as compared to controls. This suggests possible reduction in choroidal vascularity in eyes with AMD and also to a certain extent in the 'normal fellow' eyes without phenotypical manifestations and may suggest underlying choroidal morphological change leading to wet AMD.

Vural E., Acar U., Sevinc M.K., Erdurmus M., Kucuk B., Aykas S., Sobaci G.

To investigate the relationship between choroidal thicknesses (CT), central foveal thicknesses, multifocal electroretinography (mf-ERG) responses, and best-corrected visual acuity levels in patients with Stargardt disease (STGD).A total of 30 eyes of 30 patients with STGD, and 30 age- and sex-matched healthy controls were included in the study. All participants underwent detailed ophthalmic examination including best-corrected visual acuity and spectral domain optical coherence tomography measurements, and also patients with STGD were performed mf-ERG.The mean subfoveal CT values were 271.95 ± 85.57 μm in patients with STGD and 355.73 ± 87.41 μm in the control group (P < 0.001). The mean central foveal thickness values were 223.56 ± 61.38 μm in patients with STGD and 272.46 ± 27.52 μm in the control group (P < 0.001). The mean central and paracentral mf-ERG responses (45.71 ± 26.60 and 16.47 ± 10.75 Nv/deg respectively) in patients with STGD were significantly lower from the normal ranges (66.6-130.8 Nv/deg and 30.9-77.7 Nv/deg, respectively; P < 0.001 for both). There was a statistically significant correlation between subfoveal CT and best-corrected visual acuity levels (P = 0.012, r = -0.452), and between parafoveal CT and inner retinal thickness and paracentral mf-ERG responses (P = 0.043, r = +0.372 and P = 0.049, r = +0.363, respectively). Paracentral mf-ERG responses were also correlated with outer retinal thickness values (P = 0.005, r = +0.503).Patients with STGD have a thinner CT, which may be responsible for some of the clinical findings. The pathophysiological significance of these findings needs further study.

Ayyildiz O., Ozge G., Kucukevcilioglu M., Ozgonul C., Mumcuoglu T., Durukan A.H., Mutlu F.M.

Bojinova R.I., Türksever C., Schötzau A., Valmaggia C., Schorderet D.F., Todorova M.G.

To evaluate the relationship between the peripapillary metabolic alterations [retinal vessel Oximetry (RO)] and the structural findings [retinal vessel diameter and retinal nerve fibre layer thickness (RNFL)] in patients with inherited retinal dystrophies (IRD).Patients with IRD [24 patients with rod-cone dystrophy (RCD), 15 patients with cone-rod dystrophy, 13 patients with inherited maculopathy] and 18 age-matched controls, who underwent RO imaging and spectral domain optical coherence tomography, were included. The average and quadrant oxygen saturation in all four major peripapillary retinal arterioles (A-SO2 ) and venules (V-SO2 ) were measured, and their difference (A-V SO2 ) was calculated. The corresponding retinal vessel diameter of these arterioles (D-A) and venules (D-V) was measured. The data were compared to the peripapillary RNFL thickness within the IRD subgroups and to the data obtained in the controls.In general, patients with IRD had higher average V-SO2 values when compared to controls (p ≤ 0.029). Rod-cone dystrophy (RCD) patients differed from controls, but also from patients with other IRDs, when the average and quadrant oxygen saturation values (A-SO2 and V-SO2 ) were evaluated (p ≤ 0.026). Within the RCD group, the correlations of RNFL thickness to V-SO2 , A-V SO2 , D-A and D-V were significant (p ≤ 0.030), thus indicating a different relationship between the RNFL thickness and the examined parameters, when compared to the other groups.It becomes evident from our combined metabolic-structural approach that a prediction model, to identify which individual is at risk of developing a photoreceptor degeneration of RCD type, can be proposed. It will take into account the peripapillary retinal oxygen saturation, the retinal vessel diameter and the RNFL thickness values.

Miyata M., Hata M., Ooto S., Ogino K., Gotoh N., Morooka S., Hasegawa T., Hirashima T., Sugahara M., Kuroda Y., Yamashiro K., Yoshimura N.

To compare atrophy of the choroid and retina between Bietti crystalline dystrophy (BCD) patients and EYS-related retinitis pigmentosa (RP) patients with a similar degree of central visual field defects, age, and axial length (AL).Nine eyes of nine BCD patients with CYP4V2 mutations (BCD group) were examined. Moreover, we selected 10 eyes of 10 RP patients with EYS mutations matched for age, axial length, and mean deviation (measured with the 10-2 SITA standard program; EYS-RP group), and 10 eyes of 10 normal volunteers matched for age and axial length (control group). Macular thicknesses of the choroid and retina were measured via swept-source optical coherence tomography.The macular choroid was significantly thinner in the BCD group than in the EYS-RP and control groups, although the thickness did not significantly differ between the EYS-RP and control groups. The macular retina was significantly thinner in the BCD and EYS-RP groups than in the control group, although the thickness did not significantly differ between the BCD and EYS-RP groups at most sites.Bietti crystalline dystrophy patients with CYP4V2 mutations showed more severe macular choroid atrophy as compared to EYS-related RP patients. These different damage patterns suggest differences in choroidal expression between CYP4V2 and EYS.

Ng W.Y., Ting D.S., Agrawal R., Khandelwal N., Htoon H.M., Lee S.Y., Wong T.Y., Cheung G.C.

To evaluate choroidal structural changes in eyes with myopic choroidal neovascularization (mCNV) treated with anti-VEGF over 12 months.We prospectively evaluated subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) using spectral-domain optical coherence tomography (SD-OCT) at baseline, 6, and 12 months in both eyes in patients presenting with unilateral mCNV. Choroidal vascularity index was defined as the ratio of luminal area to total choroidal area after SD-OCT images were binarized digitally.We included 20 patients (20 eyes with mCNV and 20 fellow eyes without mCNV) with mean age of 60.35 ± 10.85 years. At baseline, mean SFCT and CVI was similar between eyes with mCNV and fellow eyes (69.20 ± 63.04 μm vs. 67.10 ± 65.74 μm, P = 0.713 for SFCT and 59.44 ± 3.92% vs. 59.03 ±. 5.58%, P = 0.958 for CVI). Subfoveal choroidal thickness decreased significantly in the mCNV eyes to 54.75 ± 45.43 μm (P = 0.017) at 12 months after anti-VEGF therapy, whereas SFCT in the contralateral eyes did not change significantly. There was no significant change in CVI in mCNV eyes or contralateral eyes from baseline to 12 months. Thinning of SFCT did not influence final BCVA.Thinning of subfoveal choroid without alteration in CVI was observed in eyes with mCNV treated with anti-VEGF therapy over 12 months. This finding may be explained by mechanical stretching in response to globe expansion.

Wei X., Ting D.S., Ng W.Y., Khandelwal N., Agrawal R., Cheung C.M.

To evaluate choroidal structural changes in exudative age-related macular degeneration (AMD) using choroidal vascularity index computed from image binarization on spectral domain optical coherence tomography with enhanced depth imaging.This prospective case series included 42 consecutive patients with unilateral exudative AMD. Choroidal images were segmented into luminal area and stromal area. Choroidal vascularity index was defined as the ratio of luminal area to total choroid area. Mean choroidal vascularity index and mean choroidal thickness between study and fellow eyes of the same patient with dry AMD were compared using Student's t-test.There was a significantly lower choroidal vascularity index in eyes with exudative AMD (60.14 ± 4.55 vs. 62.75 ± 4.82, P < 0.01). Luminal area (P < 0.01) was decreased in eyes with exudative AMD but there was no significant difference in total choroid area (P = 0.05) and choroidal thickness (P = 0.93) between study and fellow eyes.Eyes with exudative AMD demonstrated reduced choroidal vascularity index but insignificant differences in choroidal thickness compared with their fellow eyes. Choroidal vascularity index may be a potential noninvasive tool for studying structural changes in choroid and monitoring choroidal disease in exudative AMD.

Agrawal R., Li L.K., Nakhate V., Khandelwal N., Mahendradas P.

We assessed the application of the choroidal vascularity index (CVI) in the follow-up of Vogt-Koyanagi-Harada disease (VKH) patients derived from image binarization of enhanced depth imaging optical coherence tomography (EDI-OCT) images with Fiji software. Our secondary objective was to derive the retinochoroidal vascularity index based on en face fundus fluorescein and indocyanine green angiography (FFA and ICGA).In this retrospective cohort study, EDI-OCT scans of 18 eyes of 9 patients with VKH were obtained at baseline within 2 weeks of acute presentation, and again at 6 to 12 months. Images with poor quality were excluded. Choroidal thickness (CT) and CVI were analyzed and compared to 13 eyes of 13 healthy controls. En face FFA and ICGA obtained from 12 eyes of 7 patients were segmented to derive retinochoroidal vascularity index.There was no statistical difference in age or sex between the study group and controls. Choroidal thickness of patients with VKH was 359.23 ± 57.63 μm at baseline, compared to 274.09 ± 56.98 μm in controls (P = 0.003). Follow-up CT in VKH patients was 282.62 ± 42.51 μm, which was significantly decreased from baseline (P = 0.0001). Choroidal vascularity index in VKH patients was 70.03 ± 1.93% at baseline, compared to 64.63 ± 1.92% in controls (P < 0.001). Choroidal vascularity index was 66.94 ± 1.82% at follow-up, significantly reduced from baseline (P < 0.0001). Fundus fluorescein angiography and ICGA retinochoroidal vascularity indices at baseline were 70.67 ± 2.65% and 66.42 ± 2.16%, respectively.In this small series of VKH patients, EDI-OCT-derived CVI had a statistically significant reduction over time, similar to CT. We propose that OCT, FFA, and ICGA-derived vascularity indices may be potential novel supportive tools in monitoring disease progression in VKH.Choroidal vascularity index can be used potentially to study and analyze the structural changes in choroid. It can be a useful tool to explain the changes in the CT in different retinochoroidal disorders. Choroidal vascularity index also can be used for longitudinal follow-up in patients with VKH disease and other inflammatory disease involving the choroid.

Tan K., Laude A., Yip V., Loo E., Wong E.P., Agrawal R.

To propose the use of choroidal vascularity index (CVI) as a novel tool to assess vascular status of the choroid using image binarization of enhanced depth imaging (EDI) optical coherence tomography (OCT) scans in diabetes mellitus (DM).A prospective cross-sectional study was performed at a tertiary referral eye care centre in Singapore. Age and gender matched EDI-OCT scans of 38 eyes of 19 patients with DM were compared with eyes of healthy controls (n = 19). The choroidal images were binarized into luminal areas (LA) and stromal areas (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to total circumscribed subfoveal choroid area (TCA). Mean choroidal thickness, mean retinal thickness and mean CVI between patients and controls were compared using student's t-test.There were no significant differences in TCA (p = 0.78), LA (p = 0.90), SA (p = 0.33), average choroidal (p = 0.40) or retinal thickness (p = 0.70) between patients with DM and controls. However, there was a significantly lower CVI in patients with DM as compared to controls (65.10 ± 0.20 versus 67.20 ± 0.16, p < 0.0001).Eyes of patients with DM showed decreased CVI with no corresponding change in choroidal thickness. Image binarization may be potentially useful as a tool to assess choroidal structures and vasculature.

Agrawal R., Chhablani J., Tan K., Shah S., Sarvaiya C., Banker A.

To evaluate choroidal vascularity index (CVI) in eyes with central serous chorioretinopathy (CSC) using an image binarization tool on enhanced depth imaging using spectral domain optical coherence tomography scans.In this retrospective cohort study, enhanced depth imaging optical coherence tomography scans of both eyes of patients with CSC were taken at baseline; they were segmented and compared with enhanced depth imaging optical coherence tomography scans of fellow eyes without CSC as well as age-matched healthy subjects. Subfoveal choroidal area (1,500 μm) was segmented into luminal area and stromal area using image binarization. Choroidal vascularity index was defined as the proportion of luminal area to the total circumscribed subfoveal choroidal area.Eyes with acute CSC (32 eyes) had significantly higher CVI compared with their fellow eyes (27 eyes) (P < 0.0001), 19 eyes with resolved CSC (P < 0.0001) and with 30 eyes of age-matched healthy eyes (P < 0.0001). Fellow eyes of subjects with acute CSC also had significantly higher CVI compared with eyes with resolved CSC (P < 0.0001) and age-matched healthy eyes (P < 0.0001).Increased CVI suggests increased vascular component compared with the stromal component in acute CSC. Increased CVI was noted in fellow eye of the subjects with acute CSC in comparison with age-matched healthy subjects. The CVI could be a useful index for early diagnosis of CSC and to assess the treatment response after laser photocoagulation or photodynamic therapy.

Dalvin L.A., Pulido J.S., Marmorstein A.D.

Agrawal R., Gupta P., Tan K., Cheung C.M., Wong T., Cheng C.

The vascularity of the choroid has been implicated in the pathogenesis of various eye diseases. To date, no established quantifiable parameters to estimate vascular status of the choroid exists. Choroidal vascularity index (CVI) may potentially be used to assess vascular status of the choroid. We aimed to establish normative database for CVI and identify factors associated with CVI in healthy eyes. In this population-based study on 345 healthy eyes, choroidal enhanced depth imaging optical coherence tomography scans were segmented by modified image binarization technique. Total subfoveal choroidal area (TCA) was segmented into luminal (LA) and stromal (SA) area. CVI was calculated as the proportion of LA to TCA. Linear regression was used to identify ocular and systemic factors associated with CVI and subfoveal choroidal thickness (SFCT). Subfoveal CVI ranged from 60.07 to 71.27% with a mean value of 65.61 ± 2.33%. CVI was less variable than SFCT (coefficient of variation for CVI was 3.55 vs 40.30 for SFCT). Higher CVI was associated with thicker SFCT, but not associated with most physiological variables. CVI was elucidated as a significant determinant of SFCT. While SFCT was affected by many factors, CVI remained unaffected suggesting CVI to be a more robust marker of choroidal diseases.

Agrawal R., Salman M., Tan K., Karampelas M., Sim D.A., Keane P.A., Pavesio C.

Purpose To compute choroidal vascularity index (CVI) using an image binarization tool on enhanced depth imaging (EDI)-optical coherence tomography (OCT) scans as a non-invasive optical tool to monitor progression in panuveitis and to investigate the utility of volumetric data from EDI-OCT scans using custom image analysis software. Materials and Methods In this retrospective cohort study, segmented EDI-OCT scans of both eyes in 19 patients with panuveitis were taken at baseline and at 3-month follow-up and were compared with EDI-OCT scans of normal eyes. Subfoveal choroidal area was segmented into luminal (LA) and stromal interstitial area (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to the total circumscribed subfoveal choroidal area (TCA). Results The mean choroidal thickness was 265.5±100.1μm at baseline and 278.4±102.6μm at 3 months follow up (p = 0.06). There was no statistically significant difference in TCA between study and control eyes (p = 0.08). CVI in the control group was 66.9±1.5% at baseline and 66.4±1.5% at follow up. CVI was 74.1±4.7% at baseline and 69.4±4.8% at 3 months follow up for uveitic eyes (p

Demin N.S., Ilyasova N.Y., Samigullin R.Т.

The paper proposes a technology for extraction of vascular tissue of the human eye and calculation of chorioidal vascular index on optical coherence tomography images. The applied approach is based on the use of the method of shadow compensation of optical coherence tomography (OCT) images with their subsequent filtering and binarisation. The technology made it possible to automate the calculation of chorioidal vascular index value, which is an important indicator in the study of the vascular layer when diagnosing eye diseases.

Kumar M., Trinh M., Zhang A., Wei X., Agrawal R., Nivison-Smith L.

AbstractChoroidal vascularity index (CVI) is an image-based metric applied to assess the choroid in disease but poorly explored in natural aging. In this retrospective cohort study, we assessed a single eye of 309 healthy individuals from 20 to 70 + years, and quantified spatial topography of total choroidal area (TCA), luminal area (LA), stromal area (SA) and CVI (LA: TCA) in cluster and standard retinal templates using a semi-automated approach. CVI was found to be greatest in the central vs. periphery (CVIcentral 67.08% [66.85–67.73] vs. CVIperiphery65.68% [65.32–66.01], p < 0.01). In this study, CVI also showed no significant change with age or physiological factors. Area parameters demonstrated greater magnitude in the central versus periphery but with a superior bias: TCAsuperior 0.227mm2 [0.223–0.233] vs. TCAinferior 0.207mm2 [0.201–0.213], p < 0.01.They also showed a linear decline with age (TCA:-0.00112 to -0.00169 mm2/year; LA: -0.00074 to -0.00112 mm2/year; SA: -0.00039 to -0.00056 mm2/year, p < 0.0001), with a higher rate of decline inferiorly (p < 0.001). This study demonstrates that CVI exhibits specific spatial differences across macula, independent of age. It further establishes a comprehensive, normative database of CVI and other choroidal angioarchitecture metrics which is a valuable resource for distinguishing pathological changes from normal age-related variations in future assessments of choroid-involving diseases.

Yesilirmak N., Kurt B., Aktas A., Behar-Cohen F., Bourges J.

To compare the choroidal thickness (CT) and choroidal vascularity index (CVI) values in ocular rosacea (OR) patients across skin subtypes of the disease and healthy controls.

Demin N.S., Ilyasova N.Y., Samigullin R.T.

This paper proposes a technology for the extraction of the vascular tissue of the human eye and calculation of the choroidal vascular index on optical coherence tomography (OCT) images. The choroid is one of the most vascularized structures of the human body and plays an indispensable role in the nutrition of photoreceptors. The applied approach is based on the use of the method of shadow compensation of OCT images with their subsequent filtering and binarization. The technology for isolating the choroidal region and quantitatively assessing the choroidal vascular index (CVI) on OCT images to identify endocrine ophthalmopathy (EOP) is considered. This technology has made it possible to automate the calculation of choroidal vascular index value, which is an important indicator in the study of the vascular layer when diagnosing eye diseases.

Bellemo V., Kumar Das A., Sreng S., Chua J., Wong D., Shah J., Jonas R., Tan B., Liu X., Xu X., Tan G.S., Agrawal R., Ting D.S., Yong L., Schmetterer L.

Abstract Spectral-domain optical coherence tomography (SDOCT) is the gold standard of imaging the eye in clinics. Penetration depth with such devices is, however, limited and visualization of the choroid, which is essential for diagnosing chorioretinal disease, remains limited. Whereas swept-source OCT (SSOCT) devices allow for visualization of the choroid these instruments are expensive and availability in praxis is limited. We present an artificial intelligence (AI)-based solution to enhance the visualization of the choroid in OCT scans and allow for quantitative measurements of choroidal metrics using generative deep learning (DL). Synthetically enhanced SDOCT B-scans with improved choroidal visibility were generated, leveraging matching images to learn deep anatomical features during the training. Using a single-center tertiary eye care institution cohort comprising a total of 362 SDOCT-SSOCT paired subjects, we trained our model with 150,784 images from 410 healthy, 192 glaucoma, and 133 diabetic retinopathy eyes. An independent external test dataset of 37,376 images from 146 eyes was deployed to assess the authenticity and quality of the synthetically enhanced SDOCT images. Experts’ ability to differentiate real versus synthetic images was poor (47.5% accuracy). Measurements of choroidal thickness, area, volume, and vascularity index, from the reference SSOCT and synthetically enhanced SDOCT, showed high Pearson’s correlations of 0.97 [95% CI: 0.96–0.98], 0.97 [0.95–0.98], 0.95 [0.92–0.98], and 0.87 [0.83–0.91], with intra-class correlation values of 0.99 [0.98–0.99], 0.98 [0.98–0.99], and 0.95 [0.96–0.98], 0.93 [0.91–0.95], respectively. Thus, our DL generative model successfully generated realistic enhanced SDOCT data that is indistinguishable from SSOCT images providing improved visualization of the choroid. This technology enabled accurate measurements of choroidal metrics previously limited by the imaging depth constraints of SDOCT. The findings open new possibilities for utilizing affordable SDOCT devices in studying the choroid in both healthy and pathological conditions.

Quiroz-Reyes M.A., Quiroz-Gonzalez E.A., Quiroz-Gonzalez M.A., Lima-Gomez V.

Tellioglu A., Aydin R.

Retinitis pigmentosa (RP) is an inherited degenerative disease characterized by night blindness (nyctalopia), visual field defects, and varying degrees of vision loss. Choroid tissue has an essential role in the pathophysiology of many chorioretinal diseases. The choroidal vascularity index (CVI) is a choroidal parameter obtained as the ratio of the luminal choroidal area to the total choroidal area. The study aimed to compare the CVI of RP patients with and without CME with each other and with healthy individualsAU: Please confirm that the provided email ''[email protected]" is the correct address for official communication, else provide an alternate e-mail address to replace the existing one.. A retrospective, comparative study of 76 eyes of 76 RP patients and 60 right eyes of 60 healthy subjects was conducted. The patients were divided into two groups: those with and those without cystoid macular edema (CME). The images were obtained using enhanced depth imaging optical coherence tomography (EDI-OCT). CVI was calculated by using the binarization method with ImageJ software. The mean CVI was significantly lower in RP patients compared to the control group (0.61±0.05 and 0.65±0.02, respectively, p

Bayat K., Hassanpour K., Sabbaghi H., Fekri S., Daftarian N., Motevasseli T., Suri F., Kheiri B., Yaseri M., Ahmadieh H.

Abstract Purpose To evaluate the choroidal structure in patients with inherited retinal diseases (IRDs) by investigating the choroidal vascularity index (CVI). Methods The present study was conducted on 113 IRD patients and 113 sex- and age-matched healthy individuals. Patients’ data was extracted from the Iranian National Registry for IRDs (IRDReg®). Total choroidal area (TCA) was determined between retinal pigment epithelium and choroid-scleral junction,1500 microns on either side of the fovea. Luminal area (LA) was considered as the black area corresponding to the choroidal vascular spaces, following Niblack binarization. CVI was calculated as the ratio of the LA to the TCA. CVI and other parameters were compared among different types of IRD and the control group. Results The IRD diagnosis included retinitis pigmentosa (n = 69), cone-rod dystrophy (n = 15), Usher syndrome (n = 15), Leber congenital amaurosis (n = 9), and Stargardt disease (n = 5). Sixty-one (54.0%) individuals of each of the study and control groups were male. The average CVI was 0.65 ± 0.06 in the IRD patients and 0.70 ± 0.06 in the control group (P < 0.001). Accordingly, the average of TCA and LA were 2.32 ± 0.63 and 1.52 ± 0.44 mm [1] in patients with IRDs, respectively. The measurements for the TCA and the LA were significantly lower in all subtypes of IRD (P-values < 0.05). Conclusion CVI is significantly lower in patients with IRD than in healthy age-matched individuals. Choroidal changes in IRDs may be related to the changes in the lumen of the choroidal vessels rather than the stromal changes.

Yuan H., Dou H., Li X.

ObjectiveTo report a case of torpedo maculopathy with multimodal fundus imaging methods, and apply the choroid vascularity index to quantitatively describe the choroidal structural changes in torpedo maculopathy.Case presentationAn asymptomatic 41-year-old Chinese woman with an incidentally found yellowish-white macular lesion in her left eye was referred to our hospital. She was unaware of any prior medical conditions. The best corrected visual acuity (BCVA) was 20/20 OD and 20/25 OS, respectively. Fundus exam of her left eye revealed a well-circumscribed torpedo-like hypopigmented lesion in the macula region, and the tapered edge directed toward the fovea. Pigment deposition could be seen in the inferotemporal portion of the torpedo lesion. Fluorescein angiography showed the corresponding window defect without leakage and fundus autofluorescence demonstrated low signal throughout the lesion. Enhanced depth imaging optical coherence tomography revealed outer retinal attenuation, subretinal cavitation, subtle inner choroidal excavation and thinning of outer nuclear layer. The diagnosis of torpedo maculopathy was clinically made. Choroidal vascularity index (CVI) and sub-foveal choroidal thickness (SFCT) were applied to display changes of choroidal structure. The results implied that both subfoveal CVI and SFCT of the affected eye seemed relatively lower when compared with the fellow eye. Optical coherence tomography angiography showed reduced density of the choriocapillaris in the temporal area of the lesion and increased capillary density in the nasal area. Functional examinations, including microperimetry, multifocal electroretinogram and static perimetry also revealed reduced retinal sensitivity, decreased stimulated amplitude and suspected scotoma in the lesion area. After 12 months of follow-up, the patient’s visual acuity and the clinical appearance of the lesion were unchanged.ConclusionThe torpedo maculopathy may be identified by abnormal appearance with multimodal imaging. Decreased choroidal vascularity in the lesion area measured quantitatively by choroid vascularity index may play a role in pathogenesis of torpedo maculopathy.

Quiroz-Reyes M.A., Quiroz-Gonzalez E.A., Quiroz-Gonzalez M.A., Lima-Gomez V.

The choroidal vascularity index (CVI) is derived from the novel technique of assessing the choroidal vasculature by quantifying vascular flow using optical coherence tomography (OCT) images. Several retinal and choroidal diseases have been characterized using this index. However, no study has established the association of CVI with myopic traction maculopathy (MTM). This study aimed to investigate the association of CVI with different stages of surgically resolved MTM. We performed a consecutive, interventional, one-surgeon, and case-series study of 6 eyes of six patients enrolled between April 2017 and June 2022. One normal emmetropic eye (emmetropic control), one healthy myopic vision (healthy myopic control), and four surgically resolved myopic eyes at different stages of MTM (surgery group) were evaluated using OCT. The OCT images were binarized, and the total choroidal area (TCA, mm2), vascular luminal area (LA, mm2), and choroidal stromal area (SCA, mm2) were quantified using ImageJ software. The CVI (%) was calculated as the ratio of LA to TCA. The primary outcome measure was the association of the CVI with the best-corrected visual acuity in either of the study eyes. The baseline patient characteristics were similar (P > 0.05), except for visual acuity, which was better in the control eyes (P < 0.05). The CVI was 68.2% in the emmetropic control eye and 61.5% in the healthy myopic vision, whereas the mean CVI in the surgical group was 47.8% (40.9–53.3, min to max) (P = 0.07).

Ataş F., Kayabaşı M., Saatci A.O.

To evaluate and compare the vessel density (VD) using swept-source optical coherence tomography angiography (OCT-A) and the choroidal vascularity index (CVI) using spectral-domain optical coherence tomography (SD-OCT) in patients with Bietti crystalline dystrophy (BCD) and retinitis pigmentosa (RP).A cross-sectional retrospective study was conducted on 26 eyes of 13 BCD patients, 26 eyes of 13 RP patients, and 26 eyes of 13 age- and gender-matched healthy individuals. BCD patients were further staged as having early, intermediate, and advanced disease. VD was assessed in five quadrants of the macula (superior, temporal, inferior, nasal, and center) using a modified ETDRS technique with OCT-A. SD-OCT scans were binarized using Niblack's autolocal threshold, and CVI was determined as the ratio of the luminal area to the total choroidal area.A significant difference was found in VD in all quadrants of the superficial capillary plexus (SCP) and the deep capillary plexus (DCP) slabs among the three groups (p < 0.001). A statistically significant difference was noted in the mean VD of temporal and inferior quadrants of the SCP and between the BCD and RP groups (p = 0.005, p = 0.015, respectively). A statistically significant difference was observed in the mean VD of the temporal, inferior, and nasal quadrants between the BCD and RP groups on DCP slabs (p = 0.002, p = 0.003, p = 0.003, respectively). The mean central choroidal thickness was 214.65±87.10 μm in the BCD group, 351.69±67.94 μm in the RP group, and 320.92±59.26 μm in the control group (p < 0.001). We found that CVI was significantly higher in the control group than BCD group (p < 0.001), and it was significantly lower in the BCD group when compared to the RP group (p < 0.001).There was no difference in CVI between RP and control groups (p = 0.948). Furthermore, the CVI was significantly lower in the intermediate and advanced disease stages than the early disease stage in the subgroup analysis of BCD patients (p < 0.001, p < 0.001, respectively).CVI is a novel investigative tool to monitor disease progression. The CVI value was lower in BCD and RP patients than in the healthy subjects, and lower CVI values seem to be related to the disease severity in BCD patients. VD was also significantly lower in BCD patients when compared to RP patients, and VD analysis may help clinicians better understand the disease pathophysiology.

Abdolrahimzadeh S., Di Pippo M., Ciancimino C., Di Staso F., Lotery A.J.

Retinitis pigmentosa (RP) is the commonest inherited retinal dystrophy. It is characterized by progressive photoreceptor degeneration and cell death and ongoing neuronal and vascular impairment. In recent years, pathophysiological alterations of the choroid have begun to be appreciated in RP. Thus, representing a potential diagnostic and therapeutic biomarker. In particular, choroidal thickness and the choroidal vascularity index can be used to understand the pathogenesis of disease and evaluate new therapeutic possibilities. Photoreceptor changes seen in eyes with RP are directly correlated to a decrease of choroidal flow, leading to a strong association between relative choroidal ischemia and visual impairment. In this review we analyse the literature on choroidal thickness and choroidal vascularity index in patients with RP and assess whether these markers may reflect progression of disease from an anatomical and functional point of view.

Wei X., Roy R., Saurabh K., Sen P., Bhende M., Shelke K., Finocchio L., Sodi A., Virgili G., Invernizzi A., Salvetti A.P., Mishra C., Agrawal R.

This study investigated choroidal structural changes on optical coherence tomography (OCT) using choroidal vascularity index (CVI) and choroidal thickness (CT) in patients with Best vitelliform macular dystrophy (BVMD). This retrospective case control study included 78 patients with BVMD of different clinical stages and 242 age- and gender-matched healthy controls. Subfoveal OCT scans were analysed. Total choroidal area (TCA), luminal area (LA) and CT were measured after image segmentation and binarization. CVI, a novel marker for choroidal angioarchitecture, was defined as the ratio of LA to TCA. CVI and CT were compared between BVMD and control group, as well as among the BVMD subgroups. Mean CVI was lower in eyes with BVMD (65.0 ± 3.5%) compared to that in control eyes (67.5 ± 3.9%) and this was statistically significant (p < 0.0001). There was no significant difference in subfoveal CT between BVMD (302.88 ± 81.68 μm) and control (309.31 ± 65.46 μm) eyes (p = 0.4799). In the subgroup analysis, all stages of BVMD showed lower CVI compared to control while SFCT remained similar. Within the BVMD subgroups, CVI and subfoveal CT did not differ significantly and both were not shown to be associated with visual acuity. Decreased CVI was shown in eyes with BVMD compared to control eyes, while no significant difference in subfoveal CT was seen. CVI may be helpful in the understanding of choroidal pathology in BVMD.

Abdolrahimzadeh S., Formisano M., Di Pippo M., Lodesani M., Lotery A.J.

Stargardt disease is the commonest juvenile macular dystrophy. It is caused by genetic mutations in the ABCA4 gene. Diagnosis is not always straightforward, and various phenocopies exist. Late-onset disease can be misdiagnosed with age-related macular disease. A correct diagnosis is particularly critical because of emergent gene therapies. Stargardt disease is known to affect retinal pigment epithelium and photoreceptors. Many studies have also highlighted the importance of the choroid in the diagnosis, pathophysiology, and progression of the disease. The choroid is in an integral relationship with the retinal pigment epithelium and photoreceptors, and its possible involvement during the disease should be considered. The purpose of this review is to analyze the current diagnostic tools for choroidal evaluation and the extrapolation of useful data for ophthalmologists and researchers studying the disease.

Yang J., Wang X., Wang Y., Li Z., Xia H., Hou Q., Ge Y., Lei K., Liao Y., Luan Z., Li X.

To develop an automated image recognition software for the objective quantification of choroidal vascularity index (CVI) and choroidal thickness (CT) at different choroidal locations on images obtained from enhanced depth imaging optical coherence tomography (EDI-OCT), and to validate its reliability and investigate the difference and correlation between measurements made by manual and software.A total of 390 EDI-OCT scans, captured from 130 eligible emmetropic or myopic subjects, were categorized into four grades in terms of their accessibility to identify the choroidal-scleral interface (CSI) and were further assessed for CT and CVI at five locations (subfoveal, nasal, temporal, superior and inferior) by the newly developed Choroidal Vascularity Index Software (CVIS) and three ophthalmologists. Choroidal parameters acquired from CVIS were evaluated for its reliability and correlation with ocular factors, in comparison to manual measurements. Distribution of difference and correlation coefficient between CVIS and manual measurements were also analysed.Choroidal Vascularity Index Software (CVIS) demonstrated excellent intra-session reliability for CT (ICC: 0.992) and CVI (ICC: 0.978) measurements, compared to the relatively lower intra- and inter-observer reliability of manual measurements. Choroidal Vascularity Index Software (CVIS) and manual assessments had the highest correlation at nasal choroid (CT: r = 0.829, p < 0.001; CVI: r = 0.665, p < 0.001). Choroidal parameters identified with CVIS showed stronger correlations with axial length than manual measurements.This automated software, CVIS, exhibited excellent reliability compared to manual measurements, which are subject to image quality and clinical experience. With its validated clinical relevance, CVIS holds promise to serve as a flexible and robust tool in future vitreoretinal and chorioretinal studies.