The study group.

PURPOSE\nTo measure macular choroidal thickness in normal eyes at different points using enhanced depth imaging (EDI) optical coherence tomography (OCT) and to evaluate the association of choroidal thickness and age.\n\n\nDESIGN\nRetrospective, observational case series.\n\n\nMETHODS\nEDI OCT images were obtained in patients without significant retinal or choroidal pathologic features. The images were obtained by positioning a spectral-domain OCT device close enough to the eye to acquire an inverted image. Seven sections were obtained within a 5 x 30-degree area centered at the fovea, with 100 scans averaged for each section. The choroid was measured from the outer border of the retinal pigment epithelium to the inner scleral border at 500-microm intervals of a horizontal section from 3 mm temporal to the fovea to 3 mm nasal to the fovea. Statistical analysis was performed to evaluate variations of choroidal thickness at each location and to correlate choroidal thickness and patient age.\n\n\nRESULTS\nThe mean age of the 30 patients (54 eyes) was 50.4 years (range, 19 to 85 years), and 14 patients (46.7%) were female. The choroid was thickest underneath the fovea (mean, 287 microm; standard deviation, +/- 76 microm). Choroidal thickness decreased rapidly in the nasal direction and averaged 145 microm (+/- 57 microm) at 3 mm nasal to the fovea. Increasing age was correlated significantly with decreasing choroidal thickness at all points measured. Regression analysis suggested that the subfoveal choroidal thickness decreased by 15.6 microm for each decade of life.\n\n\nCONCLUSIONS\nChoroidal thickness seems to vary topographically within the posterior pole. The thickness of the choroid showed a negative correlation with age. The decrease in the thickness of the choroid may play a role in the pathophysiologic features of various age-related ocular conditions.

Enhanced Depth Imaging Optical Coherence Tomography of the Choroid in Normal Eyes

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.

/pdf/choroidal-vascularity-index-as-a-measure-of-vascular-status-13ond1ynxa.pdf

Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study

PURPOSE
To measure macular choroidal thickness (CT) in highly myopic eyes using enhanced depth imaging optical coherence tomography (OCT).


DESIGN
Retrospective, observational case series.


METHODS
Enhanced depth imaging OCT images were obtained in highly myopic eyes (> or =6 diopters [D]). Images of CT were obtained by positioning a spectral-domain OCT device close enough to the eye to acquire an inverted image. CT was measured from the outer border of the retinal pigment epithelium to the inner scleral border at 1000-mum intervals of a horizontal section from 3 mm temporal to the fovea to 3 mm nasal to the fovea. Statistical analysis was performed to evaluate CT at each location and to correlate CT with age and refractive error.


RESULTS
The mean age of the 31 patients (55 eyes) was 59.7 years (+/- 17.6 years; range, 24 to 90 years), and the mean refractive error was -11.9 D (+/- 3.7 D). The mean subfoveal CT was 93.2 microm (+/- 62.5 microm) and was correlated negatively with age (P = .006), refractive error (P < .001), and history of choroidal neovascularization (P = .013). Regression analysis suggested that subfoveal CT decreased by 12.7 mum for each decade of life and by 8.7 microm for each D of myopia.


CONCLUSIONS
The choroid in highly myopic eyes is very thin and undergoes further thinning with increasing age and degree of myopia. Abnormalities of the choroid may play a role in the pathogenesis of myopic degeneration.

Enhanced Depth Imaging Optical Coherence Tomography of Choroid in Highly Myopic Eyes

Purpose
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).

Methods
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.

Results
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).

Conclusion
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.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/aos.13044

Choroidal vascularity index - a novel optical coherence tomography parameter for disease monitoring in diabetes mellitus?

The principal markers of diabetic eye disease are the breakdown of the blood-retinal barrier, retinal vasculature integrity, and hemodynamic abnormalities [1]. Clinical and experimental findings suggest that, along with retinal change, choroidal vasculopathy might also play a role in the pathogenesis of diabetic retinopathy. We further propose that it might be related to the severity of diabetic retinopathy. Various choroidal abnormalities including obstruction of the choriocapillaris, vascular degeneration, choroidal aneurysms, and choroidal neovascularization have been reported in previous studies on diabetic eyes [2-4].

Choroidal angiopathy, by contrast, has received relatively scant research attention. Until recently, the choroid could be evaluated only by indocyanine green angiography, laser Doppler f lowmetry, or ultrasound [5]. These techniques, though useful for determining vessel abnormalities or changes in the choroidal blood flow, provide no anatomical information on the retinal pigmentary epithelium or the choroidal layers. Spectral-domain optical coherence tomography (OCT) now allows for high-quality higher-resolution cross-sectional macula imaging. Additionally, enhanced-depth imaging (EDI) software enables highly reliable and reproducible measurement of choroidal thickness.

The present study, proceeding on the premise that a better clinical understanding of choroidal damage might enable a more accurate assessment of diabetic eye diseases, measured the choroidal thickness in patients with various stages of diabetic retinopathy and compared the results with those of age-matched healthy individuals.

/pdf/comparison-of-choroidal-thickness-in-patients-with-diabetes-1pm5avx1ht.pdf

Comparison of Choroidal Thickness in Patients with Diabetes by Spectral-domain Optical Coherence Tomography

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Comparison of Choroidal Thickness in Patients with Diabetes by Spectral-domain Optical Coherence Tomography