Analysis of Choroidal Vascularity in Children with Unilateral Hyperopic Amblyopia

Comparison of Retinal and Choroidal Microvasculature Changes in Monocular Amblyopic and Non-amblyopic Eyes following Short-term Patch Occlusion Treatment

PURPOSE

Our objective was to investigate whether there were differences in the short-term changes of retinal and choroidal microvasculature between amblyopic and non-amblyopic eyes after patch occlusion treatment in patients with monocular amblyopia. Additionally, we aimed to determine if these changes were associated with improvements in clinical parameters.

METHODS

We conducted a retrospective, longitudinal paired-eye case-control study by analyzing the medical records of patients under the age of 12 who had monocular amblyopia and underwent patch occlusion treatment for a duration of 2 to 12 months. Using optical coherence tomography angiography images, we compared the foveal avascular zone width, retinal blood vessel density (VD), choroidal thickness (CT), and choroidal vascularity index (CVI) in amblyopic and non-amblyopic eyes before and after patch occlusion treatment. We analyzed the correlations between the aforementioned parameters and changes in best-corrected visual acuity (BCVA) and stereopsis.

RESULTS

Overall, 114 eyes from 57 patients were enrolled. At baseline, parafoveal superficial plexus VD, foveal and parafoveal deep capillary plexus VD (DCPD) were lower by 0.994 ± 3.312% (p = .026), 2.403 ± 8.273% (p = .033), and 2.469 ± 4.095% (p < .001), respectively; CT was thicker by 30.6 ± 90.7 μm (p = .014); and CVI was higher by 1.920 ± 3.432% (p < 001) in the amblyopic eyes than in the non-amblyopic eyes. Following short-term patch occlusion treatment, foveal and parafoveal DCPD increased by 1.264 ± 3.829% (p = .017) and 1.028 ± 3.662% (p = .036), respectively, CT thinned by 15.5 ± 51.5 μm (p = .019), and CVI decreased by 1.296 ± 3.997% (p = .018) in the amblyopic eyes. Following patch occlusion treatment, as the foveal DCPD decreased and CVI increased, the BCVA improved (p = .017 and .035, respectively).

CONCLUSION

Following patch occlusion treatment, increased foveal DCPD and decreased CVI were associated with improved BCVA.

Short-term effects of occlusion therapy and optical correction on microvasculature in monocular amblyopia: a retrospective case-control study

This retrospective longitudinal case-control study investigated the short-term effects of patch occlusion treatment compared with optical correction on the microvasculature in monocular amblyopia. We included patients with monocular amblyopia treated for 2-12 months; they were classified into two groups according to the treatment regimen: patch occlusion or optical correction. Children aged < 12 years who presented to our clinic for examination without amblyopia diagnosis were enrolled as the control group. Changes in retinal and choroid microvasculature according to treatment were examined, and the correlation between changes in microvasculature and improvement in best-corrected visual acuity (BCVA) was evaluated. There were 57, 35, and 41 patients in the patch occlusion, optical correction, and control groups, respectively (mean age, 6.4 ± 2.0 years). Both amblyopic groups showed changes in the foveal and parafoveal deep capillary plexus vessel density (DCPD), choroidal thickness, and choroidal vascularity index (CVI) following short-term treatment (mean, 4.5 months). In the patch occlusion group, BCVA improved as the foveal DCPD increased (P = 0.013) and the CVI decreased (P = 0.037). In the optical correction group, BCVA improved as the foveal and parafoveal DCPD increased (P = 0.009). Increased foveal DCPD following amblyopia treatment and decreased CVI by patch occlusion were associated with improved BCVA.

Choroidal vasculature act as predictive biomarkers of long-term ocular elongation in myopic children treated with orthokeratology: a prospective cohort study

BACKGROUND

Despite receiving orthokeratology (ortho-k), the efficacy of retarding ocular elongation during myopia varies among myopic children. The current study aimed to investigate the early changes of choroidal vasculature at one month after ortho-k treatment and its association with one-year ocular elongation, as well as the role of such choroidal responses in predicting the one-year control efficacy of ortho-k treatment.

METHODS

A prospective cohort study was conducted in myopic children treated with ortho-k. Myopic children aged between 8 and 12 years who were willing to wear ortho-k lenses were recruited consecutively from the Eye Hospital of Wenzhou Medical University. Subfoveal choroidal thickness (SFCT), submacular total choroidal luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow deficit (CcFD) were evaluated by optical coherence tomography (OCT) and OCT angiography over a one-year period.

RESULTS

Fifty eyes from 50 participants (24 males) who finished one-year follow-ups as scheduled were included, with a mean age of 10.31 ± 1.45 years. The one-year ocular elongation was 0.19 ± 0.17 mm. The LA (0.03 ± 0.07 mm²), SA (0.02 ± 0.05 mm²) increased proportionally after one-month of ortho-k wear (both P < 0.01), as did the SFCT (10.62 ± 19.98 μm, P < 0.001). Multivariable linear regression analyses showed that baseline CVI (β = - 0.023 mm/1%, 95% CI: - 0.036 to - 0.010), one-month LA change (β = - 0.009 mm/0.01 mm², 95% CI: - 0.014 to - 0.003), one-month SFCT change (β = - 0.035 mm/10 µm, 95% CI: - 0.053 to - 0.017) were independently associated with one-year ocular elongation during ortho-k treatment after adjusting with age and sex (all P < 0.01). The area under the receiver operating characteristic curve of prediction model including baseline CVI, one-month SFCT change, age, and sex achieved 0.872 (95% CI: 0.771 to 0.973) for discriminating children with slow or fast ocular elongation.

CONCLUSIONS

Choroidal vasculature is associated with ocular elongation during ortho-k treatment. Ortho-k treatment induces increases in choroidal vascularity and choroidal thickness as early as one month. Such early changes can act as predictive biomarkers of myopia control efficacy over a long term. The utilization of these biomarkers may help clinicians identify children who can benefit from ortho-k treatment, and thus has critical implications for the management strategies towards myopia control.

Choroidal thickness and vascular microstructure parameters in Chinese school-age children with high using optical coherence tomography

BACKGROUND

The current study was to evaluate the choroidal thickness (CT) and vascular microstructure parameters in Chinese children with high hyperopia through enhanced depth imaging optical coherence tomography (EDI-OCT).

METHODS

Cross-sectional study. A total of 23 children with high hyperopia and 29 children with normal refractive status were retrospectively enrolled in the study. The measurement of the macular CT, 7 points: the sub-foveal area point, the temporal and nasal points at a radius of 0.5-mm, 1.5-mm, and 3-mm were measured. After binarization of the OCT images, the total choroidal area (TCA), stromal area (SA) as well as the luminal area (LA) were identified and measured. The choroidal vascularity index (CVI) was defined as the ratio of LA to TCA. The independent t-test for normal distributions and Kruskal-Wallis tests for non-normal distributions were used to compare other parameters between groups. The Tamhane's T2 test was performed to adjust for multiple comparisons between groups within each analysis.

RESULTS

The subfoveal CT (SFCT) in the high hypermetropic group was significantly thicker than that in normal controls (309.22 ± 53.14 μm vs. 291.27 ± 38.27 μm; P = 0.019). At 0.5 mm, 1.5 mm, and 3.0 mm in diameter, the nasal choroidal sectors of the high hyperopia eyes were significantly thicker than that of the control (P < 0.05). There was significant difference in the choroidal vascular parameters. TCA and LA in the high hyperopia eyes was significantly larger than that of the normal control eyes (3078129.54 ± 448271.18 μm² vs. 2765218.17 ± 317827.19 μm², 1926819.54 ± 229817.56 μm² vs. 1748817.18 ± 191827.98 μm²; P = 0.009, P = 0.011; Table 2). SA values were 1086287.55 ± 212712.11 um² in the high hyperopia eyes and 999712.71 ± 209838.12 μm² in the control eyes. The CVI and LA/SA ratio values were differed significantly in the two groups (P = 0.019, P = 0.030, respectively). AL was significantly correlated with SFCT (r = -0.325, P = 0.047), but not significantly correlated with other parameters. Spherical equivalent (SE) was significantly correlated with AL and SFCT (r = -0.711, r = 0.311; P = 0.001, P = 0.016), whereas no significant association between sphere and other parameters.

CONCLUSION

The choroidal structure of the high hyperopia eyes was different from the normal control eyes. The thicker SFCT, higher LA, and TCA were characteristic of high hyperopia eyes. Choroidal blood flow may be decreased in amblyopic eyes. SFCT of high hyperopia children abnormally increased and correlated with shorter AL and higher SE. AL and SE affect choroidal structure and vascular density.

Features of the Choroidal Structure in Children With Anisometropic Amblyopia

PURPOSE

To examine the choroidal structure in children with anisometropic amblyopia using the binarization method.

METHODS

Thirty children with unilateral anisometropic amblyopia and 30 healthy age- and sex-matched controls were included in the study. Choroidal thickness was measured with optical coherence tomography. The choroidal layer was examined with the binarization method using ImageJ software (National Institutes of Health). The total choroidal area, stromal area, luminal area, luminal area to stromal area ratio, and choroidal vascular index were calculated. The values were compared by correlating the spherical equivalent (SE) (determined by an autorefractometer) with anterior chamber depth, axial length, central corneal thickness (measured by optical biometry), and choroidal thickness values.

RESULTS

Mean SE values were 3.75 ± 2.16 diopters (D) in the amblyopic eyes, 2.39 ± 2.09 D in the fellow eyes, and -0.27 ± 0.53 D in the control eyes. Best corrected visual acuity (BCVA) was 0.29 ± 0.11 logarithm of the minimum angle of resolution (logMAR) in the amblyopic eyes, 0.02 ± 0.04 logMAR in the fellow eyes, and 0 ± 0 logMAR in the control eyes. Choroidal thickness values were 351 ± 47 µm in the amblyopic eyes, 333 ± 55 µm in the fellow eyes, and 324 ± 51 µm in the control eyes. Luminal area to stromal area ratio values were 1.73 ± 0.13 in the amblyopic eyes, 1.76 ± 0.15 in the fellow eyes, and 2.02 ± 0.25 in the control eyes. Choroidal vascular index values were 63% ± 0.02 in the amblyopic eyes, 64% ± 0.02 in the fellow eyes, and 66% ± 0.03 in the control eyes. BCVA, SE, choroidal thickness, luminal area to stromal area ratio, and choroidal vascular index were significantly different in each group. The total choroidal area, luminal area, and stromal area were similar in all eyes. No correlation was found between choroidal vascular index and choroidal thickness, anterior chamber depth, axial length, and central corneal thickness.

CONCLUSIONS

In children with anisometropic amblyopia, the total choroidal area was relatively larger in both the amblyopic and the fellow eyes compared to the control eyes. Due to the higher stromal area and lower luminal area, both the amblyopic and the fellow eyes also had lower choroidal vascular index values than control eyes. [J Pediatr Ophthalmol Strabismus. 2022;59(5):320-325.].

Microvascular assessment of macula, choroid, and optic disk in children with unilateral amblyopia using OCT angiography

PURPOSE

To investigate the microvascular changes of macula, choroid, and optic disk in children with unilateral amblyopia.

METHODS

This prospective cross-sectional study involved 39 unilateral amblyopic children and 39 age- and sex-matched heathy participants who served as control. Vessel densities of the superficial and deep capillary plexuses (SCP and DCP), foveal avascular zone (FAZ) area, macular thickness, optic disk vessel density, retinal nerve fiber layer (RNFL) thickness, choriocapillaris vessel density, and subfoveal choroidal thickness were evaluated by OCT angiography (OCTA). Meanwhile, the correlations of microvascular perfusion and structural changes of macula, choroid, and optic disk were analyzed.

RESULTS

The vessel density of SCP and DCP in the whole macula in the amblyopic group was significantly lower than that in the control group after adjusting for age, axial length, and spherical equivalents (all P < 0.05). FAZ area, macular thickness, RNFL thickness, and the optic disk vessel density were not statistically different between the amblyopic group and the control group (all P > 0.05). Subfoveal choroidal thickness of amblyopic eyes was significantly higher than that of control eyes(P = 0.032). Choriocapillaris flow void (FV) in the amblyopic group was greater than that in the control group (P = 0.013). Significant differences were observed between the fellow eyes and the control eyes in choriocapillaris FV and subfoveal choroidal thickness (P = 0.011 and P = 0.042, respectively). Foveal SCP and DCP vessel density in all studied eyes were positively correlated with the whole macular thickness, respectively (r = 0.556 and r = 0.627, respectively, both P < 0.001). Whole SCP and DCP vessel density in the amblyopic eyes were negatively correlated with choriocapillaris FV (r = -0.723, P < 0.001; r = -0.512, P = 0.001, respectively).

CONCLUSION

Children with amblyopic eyes have attenuated macular and choriocapillaris perfusion. There is a need for future studies that will investigate the pathophysiology of amblyopia in children by OCTA.

Evaluation of Choroidal Vascular Index in Amblyopic Patients

Objectives:

To compare subfoveal choroidal thickness (SFCT) and choroidal vascular index (CVI) in patients with hyperopic refractive and strabismic amblyopia and healthy subjects.

Materials and Methods:

The study included 17 patients with strabismic amblyopia (Group 1), 29 patients with hyperopic refractive amblyopia (Group 2), and 16 eyes of 16 healthy volunteers (Group 3). Best corrected visual acuity was noted in all patients and volunteers. In addition to detailed anterior and posterior segment examinations, macular images were obtained by enhanced-depth imaging mode of optical coherence tomography (OCT). SFCT measurements were made from these images and CVI was calculated using the Image J program.

Results:

No significant difference was found between the groups in terms of age, gender, and intraocular pressure (p=0.27, 0.64, and 0.85, respectively). Mean BCVAs in Group 1 were 0.57±0.16 (0.3-0.8) in the amblyopic eyes, 0.94±0.08 (0.8-1.0) in the fellow eyes, and in Group 2 were 0.61±0.17 (0.2-0.8) in amblyopic eyes, 0.92±0.1 (0.8-1.0) in fellow eyes. BCVA in Group 3 was 1.0±0 (1.0-1.0). Mean SFCT of the amblyopic eyes in Groups 1 and 2 was 341.50±60.4 (277-481) and 370.06±65.3 (247-462), respectively, and in the healthy eyes of Groups 1 and 2 and Group 3 was 321.92±68.26 (251-440), 330.35±74.00 (194-502), and 327.62±40.79 (238-385), respectively. SFCT was significantly greater in the amblyopic eyes of Group 2 compared to Group 3 (p=0.01). Mean CVI was 0.681±0.032 (0.642-0.736) in the amblyopic eyes and 0.685±0.054 (0.587-0.788) in the fellow eyes of Group 1 patients; 0.664±0.033 (0.592-0.719) in the amblyopic eye and 0.707±0.039 (0.625-0.779) in the fellow eye in Group 2 patients; and 0.689±0.031 (0.612-0.748) in Group 3 patients. CVI was significantly lower in the amblyopic eyes of Group 2 compared with fellow eyes (p=0.02) and Group 3 (p=0.025).

Conclusion:

Morphological changes may be seen in the choroid in amblyopic eyes. We observed that the choroidal stromal component is increased in hyperopic amblyopic patients especially.

How does anisometropia affect the choroidal vascularity index?

Purpose:

To investigate the choroidal vascularity index (CVI) and morphological features of the choroid in anisometropic amblyopia.

Methods:

In this prospective cross-sectional study, 39 patients with unilateral anisometropic amblyopic patients and 33 eyes of 33 healthy control participants were involved. These participants were examined in terms of axial length (AL), spherical equivalent (SE), central macular thickness (CMT), choroidal thickness (CT), total choroidal area (TCA), luminal area (LA), stromal area (SA), LA/SA ratio, and CVI. All parameters were compared between amblyopic eyes, healthy fellow eyes, and healthy control eyes. The Shapiro–Wilk tests, Chi-square test, the paired t-test, Wilcoxon signed-rank test, Mann–Whitney U test, Kruskal–Wallis test, and Pearson/Spearman correlation tests were used.

Results:

In the hyperopic patients; SE, subfoveal CT, nasal CT, temporal CT, TCA, LA, SA, and CMT were greater in amblyopic eyes than in healthy fellow eyes and control eyes (P < 0.001, P < 0.001, P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively), and CVI, LA/SA ratio, and AL were smaller in amblyopic eyes than in healthy fellow eyes and control eyes ([P < 0.001, P = 0.006], P < 0.001, and P < 0.001, respectively). In the myopic patients, subfoveal CT, nasal CT, temporal CT, TCA, LA, SA values were statistically smaller in amblyopic eyes than in healthy eyes and control eyes ([P < 0.001, P = 0.002), [P = 0.004, P = 0.012], [P = 0.012, P = 0.032], [P < 0.001, P = 0.013], [P < 0.001, P = 0.024], and [P < 0.001, P = 0.047], respectively). The differences in the AL and choroidal parameters were due to myopia and hyperopia.

Conclusion:

The choroidal structural parameters of the amblyopic eyes were different from that of the healthy eyes.

Assessment of choroidal vascularity and choriocapillaris blood perfusion in Chinese preschool-age anisometropic hyperopic amblyopia children

PURPOSE

To determine the macular and peripapillary area choroid microstructure parameters of hyperopic anisometropic amblyopia eyes and compare to fellow and age-matched control eyes. To assess the correlation between the axial length (AL), choroidal thickness (CT) and choroid microstructure parameters.

METHODS

This cross-sectional comparative, non-interventional study involved 52 hyperopic anisometropic amblyopia children and 48 age-matched heathy controls. 52 eyes with hyperopic anisometropic amblyopia and 48 age-matched control eyes were studied. The peripapillary and subfoveal CT were determined. The total choroidal area (TCA), luminal area (LA), and stromal area (SA) of the subfoveal and peripapillary choroid were measured. In addition, the correlation between the AL, CT and choroid microstructure parameters were calculated.

RESULTS

The peripapillary and subfoveal CT of the amblyopic eyes was significantly thicker than the fellow and control eyes (all P < 0.05). The subfoveal and peripapillary choroidal SA, LA and TCA of the amblyopic eyes were significantly increased than that of the fellow and control eyes (all P < 0.05). The choroidal vascularity index (CVI) values of the amblyopic eye were significantly different among the three groups (P < 0.05). There was a statistically significant negative correlation between AL and subfoveal CT (SFCT), LA and TCA levels (P < 0.001, P = 0.039, P = 0.027, respectively). Spherical equivalent (SE) was positive correlated with SFCT, LA and TCA levels (P = 0.456, 0.229 and 0.240, respectively; all P < 0.05). There was a statistically significant positive correlation between SFCT, SE, LA, SA, TCA and CVI levels (all P < 0.05).

CONCLUSION

The subfoveal and peripapillary CT of amblyopic children abnormally increased and correlated with shorter AL and higher SE. The choroidal structure of the amblyopic eyes was different from the fellow and control eyes, the hyperopic anisometropic amblyopic eyes had significantly thicker sub-foveal choroid, higher LA, SA, and TCA. AL and CT affect choroidal structure and vascular density. Choroidal blood flow may be increased in amblyopic eyes. The larger LA, SA, TCA, and lower CVI were characteristic of the amblyopic eye.

Choroidal vascularity index in adults with different refractive status

AIM

We aimed to perform structural analysis of the choroid in adults with different refractive status.

MATERIALS AND METHODS

A prospective, comparative study of 100 right eyes of 100 patients ages 18-40 years was conducted. The patients were divided into four groups according to spherical equivalent (SE): Group 1: -0.5 and above, low-to-moderate myopia; Group 2: -6 and above, high myopia; Group 3: +0.5 and above, hyperopia; Group 4: +/- 0.5, emmetropia. With the images obtained using enhanced depth imaging optical coherence tomography (EDI-OCT), the total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascular index (CVI) were calculated using the binarization method. The anterior chamber depth (ACD), axial length (AL), and central corneal thickness (CCT) values were measured by optical biometry. All parameters were compared between groups. The correlation of biometric parameters with CVI was examined.

RESULTS

Parameters were found to be statistically different between the four groups. TCA, LA, and SA values were the highest in Group 3 and lowest in Group 2. L/S ratio and CVI values in Group 3 were significantly lower than in the other groups. There was a negative correlation between AL with SE and CT, and no correlation between the CVI and other parameters.

CONCLUSION

CVI decreases when emmetropization is disrupted and changes to hypermetropia or myopia. The reason for the decrease in myopia is the reduction of the luminal area, while in hyperopia it is due to an increase in the stromal area. When there is a shift toward myopia, there is a decrease in the TCA, but the CVI does not change significantly. Unlike CT, the CVI is not affected by factors such as SE and AL; therefore, the CVI can be a useful parameter for examining choroidal changes in refractive errors.

Differences in Retinal and Choroidal Vasculature and Perfusion Related to Axial Length in Pediatric Anisomyopes

Purpose

The purpose of this study was to evaluate the interocular differences in choroidal vasculature, choriocapillaris perfusion, and retinal microvascular network, and to explore their associations with interocular asymmetry in axial lengths (ALs) in children with anisomyopia.

Methods

Refractive error, AL, and other biometric parameters were measured in 70 children with anisomyopia. Using optical coherence tomography (OCT) and OCT-angiography, we measured the submacular choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow deficit (CcFD), retinal vessel density (VD), and foveal avascular zone (FAZ) area.

Results

The mean interocular differences in spherical equivalent refraction and AL were −2.26 ± 0.94 diopters and 0.95 ± 0.46 mm, respectively. Submacular ChT, TCA, LA, SA, and CVI were all significantly lower in the more myopic (longer AL) eyes than in the less myopic (shorter AL) fellow eyes. In eyes with longer ALs, both the CcFD and FAZ areas were significantly greater, whereas the superficial and deep retinal VDs were significantly less. After adjusting for corneal power and intraocular pressure, interocular differences in LA (β = −0.774), SA (β = −0.991), and CcFD (β = 0.040) were significantly associated with interocular asymmetry in AL (all P < 0.05).

Conclusions

In pediatric anisomyopes, eyes with longer ALs tended to have lower choroidal vascularity and choriocapillaris perfusion than the contralateral eyes with shorter ALs. Longitudinal investigations would be useful follow-ups to test for a causal role of choroidal circulation in human myopia.

Choroidal vessel density in unilateral hyperopic amblyopia using en-face optical coherence tomography

Background

Structural changes of the choroid, such as choroidal thickening, have been indicated in amblyopic eyes with hyperopic anisometropia as compared to fellow or healthy eyes. The purpose of the present study was to investigate choroidal vascular density (CVD) in children with unilateral hyperopic amblyopia.

Methods

This study included 88 eyes of 44 patients with unilateral amblyopia due to hyperopic anisometropia with or without strabismus and 29 eyes of 29 age-matched normal controls. The CVD of Haller’s layer was quantified from en-face images constructed by 3-dimensional swept-source optical coherence tomography images flattened relative to Bruch’s membrane. The analysis area was a 3 × 3-mm square of macula after magnification correction. Relationships between CVD and other parameters [best-corrected visual acuity (BCVA), refractive error and subfoveal choroidal thickness (SFCT)] were investigated, and CVDs were compared between amblyopic, fellow, and normal control eyes.

Results

Mean CVD was 59.11 ± 0.66% in amblyopic eyes, 59.23 ± 0.81% in fellow eyes, and 59.29 ± 0.74% in normal control eyes. CVD showed a significant positive relationship with SFCT (p = 0.004), but no relationships with other parameters. No significant differences in CVD were evident among amblyopic, fellow, and normal control eyes after adjusting for SFCT (p = 0.502).

Conclusions

CVD was unrelated to BCVA, and CVD did not differ significantly among amblyopic, fellow and normal control eyes. These results suggest that the local CVD of Haller’s layer is unaffected in unilateral hyperopic amblyopic eyes.

Choroidal Vascularity Index: An In-Depth Analysis of This Novel Optical Coherence Tomography Parameter

Remarkable improvements in optical coherence tomography (OCT) technology have resulted in highly sophisticated, noninvasive machines allowing detailed and advanced morphological evaluation of all retinal and choroidal layers. Postproduction semiautomated imaging analysis with dedicated public-domain software allows precise quantitative analysis of binarized OCT images. In this regard, the choroidal vascularity index (CVI) is emerging as a new imaging tool for the measurement and analysis of the choroidal vascular system by quantifying both luminal and stromal choroidal components. Numerous reports have been published so far regarding CVI and its potential applications in healthy eyes as well as in the evaluation and management of several chorioretinal diseases. Current literature suggests that CVI has a lesser variability and is influenced by fewer physiologic factors as compared to choroidal thickness. It can be considered a relatively stable parameter for evaluating the changes in the choroidal vasculature. In this review, the principles and the applications of this advanced imaging modality for studying and understanding the contributing role of choroid in retinal and optic nerve diseases are discussed. Potential advances that may allow the widespread adoption of this tool in the routine clinical practice are also presented.