Choroidal thickness in normal Indian eyes using swept-source optical coherence tomography

Automatic segmentation of layers in chorio-retinal complex using Graph-based method for ultra-speed 1.7 MHz wide field swept source FDML optical coherence tomography

The posterior segment of the human eye complex contains two discrete microstructure and vasculature network systems, namely, the retina and choroid. We present a single segmentation framework technique for segmenting the entire layers present in the chorio-retinal complex of the human eye using optical coherence tomography (OCT) images. This automatic program is based on the graph theory method. This single program is capable of segmenting seven layers of the retina and choroid scleral interface. The graph theory was utilized to find the probability matrix and subsequent boundaries of different layers. The program was also implemented to segment angiographic maps of different chorio-retinal layers using "segmentation matrices." The method was tested and successfully validated on OCT images from six normal human eyes as well as eyes with non-exudative age-related macular degeneration (AMD). The thickness of microstructure and microvasculature for different layers located in the chorio-retinal segment of the eye was also generated and compared. A decent efficiency in terms of processing time, sensitivity, and accuracy was observed compared to the manual segmentation and other existing methods. The proposed method automatically segments whole OCT images of chorio-retinal complex with augmented probability maps generation in OCT volume dataset. We have also evaluated the segmentation results using quantitative metrics such as Dice coefficient and Hausdorff distance This method realizes a mean descent Dice similarity coefficient (DSC) value of 0.82 (range, 0.816-0.864) for RPE and CSI layer.

Variations in choroidal thickness between emmetropic and myopic eyes after caffeine intake

PURPOSE

To investigate the variations in choroidal thinning between emmetropic and myopic subjects after caffeine intake.

METHODS

Forty-five healthy participants (age mean ± standard deviation [SD]: 20.75 ± 1.6 years) recruited in a prospective cross-sectional study. They were divided into three groups, based on refractive error status, emmetropes (spherical equivalent [SE] -0.25 to +0.25D), myopes (SE ≥-0.50D to ˂-6.00D), and high myopes (SE ≥-6.00D). The participants underwent choroidal thickness [ChT] measurements using optical coherence tomography [OCT] (Topcon 3D OCT-1 Maestro System) at baseline, 20, 40, and 60 minutes after consuming 200 mg of caffeine. The measurements of ChT were taken from five different areas horizontally.

RESULTS

Compared to baseline measurement, the ChT significantly decreased after 200 mg caffeine intake in all conditions ( P < 0.001). There was a statistically significant difference in ChT at baseline between the refractive groups ( χ2 (2)=6.548, P = 0.038) as the high myope group showed lesser horizontal ChT within Nasal at (1 mm) area compared to the myope group ( P = 0.032), however, no other significant differences in mean scores of horizontal ChT at baseline were found. The thinning in ChT in the high myope group was lesser compared to both emmetrope and myope groups; however, it was not statistically significant ( P > 0.05).

CONCLUSION

The results of this study suggest that the reduction in ChT due to caffeine consumption is not significantly affected by the refractive status of the eye. Thus, it is safe to hypothesize that the vascular part of the choroid behaves identically to vasoconstrictive in both emmetropic and myopic eyes. The choroidal thinning found in myopic and high myopic eyes and/or the reduced choroidal vascularity index were not apparent in this study. Therefore, further longitudinal studies recruiting greater numbers of participants, including myopes and high myopes, and measuring both vascular and stromal layers to investigate such variations are warranted.

Choroidal and central macular thickness before and after treatment in post fever retinitis

PURPOSE

To study the choroidal thickness (CT) and central macular thickness (CMT) in post-fever retinitis (PFR) and their correlation with visual acuity and treatment.

METHODS

A retrospective, observational study of patients presenting with PFR from 2013 to 2021 and with spectral domain optical coherence tomography (SD-OCT) (Heidelberg®, SpectralisTM, Heidelberg, Germany) images were included. The CT and CMT were measured at presentation and at the final visit. The CT was measured subfoveally and at points 2000 µm superior, inferior, medial, and lateral from the fovea using the caliper tool.

RESULTS

Seventy-nine eyes of 65 patients were included for this study. The mean age was 39.03 (±16.00) years with female preponderance of 53.84% (n = 35). Mean follow-up duration was 30 days. Mean CT at presentation and at follow-up was 254.12 µm and 241.51 µm, respectively. CT was decreased in majority of the eyes 67.1% (n = 53) from their baseline value. Mean CMTs at presentation and final visit were 454.8 µm and 223.7 µm, respectively. Best corrected visual acuity had a positive correlation with CMT (r = 0.340; P = 0.002) and negligible correlation with CT. A significant decrease in the mean CT was noted in patients who received doxycycline either alone or in combination with a steroid as compared to those who did not receive any treatment (P < 0.001). The significance of which is unknown presently.

CONCLUSION

CMT has a greater role in determining the final visual outcome than CT. CT can be reduced post-treatment with no effect on vision.

Topography and Choroidal Thickness Measurement in Healthy Asian Indian Subjects using RTVue XR 100 Optical Coherence Tomography

PURPOSE

The purpose was to study the choroidal thickness and its profile, derived from different point locations in healthy Asian Indian subjects using RTVue XR 100 optical coherence tomography (OCT) and to determine its correlation with age, refractive error, and axial length.

METHODS

In this cross-sectional study, 300 eyes of 150 healthy subjects, with no ocular pathology, were scanned in a single session, using a line scan protocol of RTVue XR 100 OCT. Choroidal thickness was measured at the subfoveal region, and six measurements were obtained on either side of the fovea (temporal and nasal) at 500 μm interval apart, up to 3000 μm. The correlation between subfoveal choroidal thickness and age, refractive error, and axial length was assessed.

RESULTS

Three hundred eyes of 150 healthy subjects were included in the analysis. Median age of the study participants was 55 years (interquartile range [IQR]: 44-61). The median subfoveal choroidal thickness was 235 μm (IQR: 210-263). The choroidal thickness was minimum at nasal 3000 μm from the fovea, while it was maximum in the subfoveal region. The point zones which were near the fovea showed thicker choroidal thickness than the outer zones, both nasally and temporally (P < 0.00001 at all locations), and at all point locations the choroid were thicker temporally than nasally (All P < 0.00001). Subfoveal choroidal thickness showed negative correlation with age (coefficient = -0.62, P = 0.03) and axial length (correlation = -8.52, P = 0.02). A decrease in subfoveal choroidal thickness of 0.62 μm/year was found by regression analysis.

CONCLUSION

Our study provides normative database and topographic profile of choroidal thickness in the normal Asian Indian eyes using RTVue XR 100 OCT.

Choroidal Thickness in Emmetropia: An Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography-Based Study

Objectives

To investigate and determine the choroidal thickness (CT) in healthy emmetropic Turkish subjects aged between 20 and 40 years using Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography (EDI-OCT).

Methods

This study included 194 eyes of 194 healthy emmetropic subjects. All participants underwent a detailed ophthalmologic examination. Axial length (AL) was measured with optical biometry. CT measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the EDI-OCT. Central macular thickness (CMT) measurements were also performed at the same time. Participants were divided into two groups; Group 1 (age between 20 and 30 years) and Group 2 (age between 31 and 40 years). CT and CMT were compared among two groups.

Results

The mean age of all the subjects was 26.61±6.08 years, the mean AL was 23.44±0.72 mm, and the mean spherical equivalent was -0.11±0.28 Diopter. The mean subfoveal, nasal, and temporal CT was 389.27±86.61 μm, 354.54±86.86 μm, and 368.25±78.69 μm, respectively. Subfoveal and nasal CT of female participants were found thinner than male participants (p=0.013 and p=0.008, respectively). CT and CMT were found similar between Group 1 and Group 2.

Conclusion

This study showed that mean subfoveal CT and CMT was 389.27±86.61μm and 268.17±18.76 μm, respectively, among healthy emmetropic Turkish subjects. Females had thinner CT in subfoveal and nasal quadrants. In addition, age did not affect CT between 20 and 40 years.

Choroidal Thickness Measured by Ocular Coherence Tomography (SD-OCT) and Body Mass Index in Healthy Saudi Women: A Cross-sectional Controlled Study

BACKGROUND

Obesity is one of the major public health problems globally, especially among women. Obesity is associated with glaucoma, cataract, age-related macular degeneration and diabetic retinopathy. Although it is clear that the anatomy and physiologic functions of the choroid may be affected by obesity, data investigating the effect of obesity on the choroid is limited and/or unavailable for the Saudi population.

OBJECTIVE

To assess Choroidal Thickness (CT) changes in a sample of healthy Saudi Arabian women with different Body Mass Index (BMI) using Spectral-domain Ocular Coherence Tomography (SD-OCT).

METHODS

A total of 140 healthy women aged 18-29 years (mean age ± standard deviation SD, 24.5 ± 1.7 years) with different BMI, axial length (AL) ≤ 24 ± 1.0 mm, and spherical equivalent refraction (SER) of ≤ ±2.0 dioptres were enrolled for the study. The participants were age and refractionmatched, and grouped into underweight (BMI ≤ 18.0 kg/m2) (n = 30), normal (control group) (18.5-24.9 kg/m2) (n = 43), overweight (25.0-29.9 kg/m2) (n=37), and obese study groups (≥ 30.0 kg/m2) (n = 30). SD-OCT imaging was performed on one eye of each participant. Comparisons among groups for all locations and the associations between CT and other variables were examined.

RESULTS

The mean CT at the subfoveal region (285 ± 31 μm, range: 203 μm to 399 μm) was significantly greater, and it was the lowest in the nasal region (248 ± 26 μm, range 154 to 304) compared with other locations, across all the groups (p < 0.05). Compared with the control, the subfoveal choroid was thinner in the obese group (mean difference: 22.6 μm, 95% Confidence Interval; CI: 8.6 μm to 36.6 μm; p = 0.02) and across all locations (p < 0.05) but thicker at the temporal location in the underweight group (12.4 μm, 95% CI: -23.7 μm to -1.04 μm; p = 0.01). No significant association of subfoveal CT with any of the measured parameters, including age (p-values ranged from 0.10 to 0.90), was found.

CONCLUSION

BMI may have an influence on the CT of healthy individuals and could be a cofounder in research studies on CT. It is, therefore, recommended that BMI should be evaluated in the clinical diagnosis and management of conditions associated with choroid in healthy individuals.

Disc–fovea distance and choroidal thickness: is there a relationship?

Background:

The distance between the optic disc center and the fovea is a biometric parameter; however, it is unclear whether DFD (disc–fovea distance) affects the choroidal thickness.

Objective:

The aim of this study is to investigate the association between DFD and choroidal thickness.

Design:

This is a prospective, and cross-sectional study.

Methods:

Two hundred fifty eyes of 250 healthy participants were examined in terms of DFD, age, axial length, spherical equivalent, and choroidal thickness. Inclusion criteria included aged between 20–40 years, no posterior segment disorders, and participants with best-corrected visual acuity (10/10 according to Snellen’s chart). Participants with high hypermetropia (>4 diopter) or myopia (>6 diopter) or any systemic disease likely to affect choroidal thickness were excluded. Choroidal thickness measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the enhanced-depth imaging optical coherence tomography.

Results:

The mean age of all the participants was 26.21 ± 5.73 years, mean DFD was 4634.29 ± 274.70 µm, mean axial length was 23.62 ± 0.83 mm, and mean spherical equivalent was −0.61 ± 1.06 diopter. The mean subfoveal, nasal, and temporal choroidal thicknesses were 388.73 ± 90.15 µm, 351.26 ± 88.09 µm, and 366.50 ± 79.56 µm, respectively. A negative correlation was found between subfoveal, nasal, and temporal choroidal thicknesses and axial length (r = −0.157, p = 0.013; r = −0.168, p = 0.008; r = −0.174, p = 0.006, respectively). Insignificant correlation was found between choroidal thicknesses and spherical equivalent (p > 0.05). There was not a statistically significant correlation between DFD and subfoveal, nasal, and temporal choroidal thicknesses (r = −0.028, p = 0.655; r = 0.030, p = 0.641; r = −0.025, p = 0.699, respectively). In addition, there was not a statistically significant correlation between age and choroidal thickness.

Conclusion:

This study shows that DFD and spherical equivalent do not affect choroidal thickness; axial length negatively affects choroidal thickness. In addition, age does not affect choroidal thickness between 20 and 40 years.

Retinal and Choroidal Thickness in Myopic Young Adults

The retinal and the choroidal thickness were measured at four locations along the horizontal direction (foveola, one nasal to the fovea and two temporal) in a group of 43 young adults (mean age: 27.1 ± 3.9 years), with ocular refraction ranging from emmetropia to high myopia (0 to −10D). Thickness values were obtained from OCT images centered at the foveal depression. The retinal thickness exhibited a correlation with refraction at all eccentricities but not at the fovea. When different subgroups of refraction were considered, the analysis of such correlations indicated that only the retinal thickness in the group of high myopia (refraction ≤ −6D) was statistically different from the other two groups (emmetropes: [−0.5, 0] D, and myopes: (−6, −0.5) D). No significant differences were found between emmetropic and myopic groups. In contrast to the retina, the choroidal thickness exhibited a significant correlation with refraction at the fovea, although such dependency only stood for high myopes (the choroid of myopes and emmetropes exhibited similar thickness). Correlation with refraction was also found at the nasal location, arising between emmetropic and high myopia groups. Other choroidal locations among groups did not exhibit relationship with the refraction. It is concluded that the differences in the choroid and retina thickness along the horizontal meridian as a function of refraction do not characterize the onset and progression of myopia at early stages, since they only manifest in the group of high myopia.

Myopia in India

India is a culturally and geographically diverse nation. Its vast demographic nature does not allow a single definition for any of the given medical conditions in its territory. One important clinical condition which has created an uproar in the rest of the world is myopia. Its cause, prevalence, etiopathogenesis and other factors are being explored constantly; however, data with respect to Indian subcontinent are genuinely missing. Hence, in this review, we enumerate the country’s myopia journey from last 4 decades. The epidemiology, genetics, ocular/systemic association, quality of life, imaging, and management in myopia with necessary future directives are discussed to augment the overall management in future.

Evaluation of Choroidal Thickness Using Optical Coherent Tomography: A Review

The choroid is the main source of blood and nourishment supply to the eye. The dysfunction of the choroid has been implicated in various retinal and choroidal diseases. The identification and in-depth understanding of pachychoroid spectrum disorders are based on the tremendous progress of optical coherence tomography (OCT) technology in recent years, although visibility of choroid is challenging in the era of the time or spectral domain OCT. The recent rapid revolution of OCTs, such as the enhanced depth imaging OCT and the swept-source OCT, has greatly contributed to the significant improvement in the analysis of the morphology and physiology of the choroid precisely, especially to the choroid-scleral boundary and vasculature. The present review highlights the recently available evidence on the measurement methodology and the clinical significance of choroidal thickness in retinal or choroidal disorders.

Distribution of Choroidal Thickness and Choroidal Vessel Dilation in Healthy Japanese Individuals

Purpose

To report fundamental epidemiologic data for choroidal parameters such as choroidal thickness and index of choroidal vascularity in Japanese individuals and to evaluate their correlations with age, sex, systemic parameters, and other ocular parameters.

Design

Population-based cohort study.

Participants

A total of 9850 individuals participated in the first follow-up of the Nagahama Prospective Cohort for Comprehensive Human Bioscience (the Nagahama Study) conducted between 2013 and 2016.

Methods

All participants underwent standardized ophthalmic examinations, including OCT with enhanced depth imaging (EDI; RS-3000 Advance; Nidek). We manually segmented the choroidoscleral interface to measure subfoveal choroidal thickness (SFCT) and calculated the normalized choroidal intensity obtained with EDI (NCI_EDI) and choroidal vascularity index (CVI). These are indices of choroidal brightness in OCT and reportedly represent the dilation of choroidal vessels. After summarizing the age-sex stratified distributions of SFCT, NCI_EDI, and CVI, their associations with age, sex, axial length (AL), and spherical equivalent (SE) were evaluated using linear regression analysis with adjustments for possible confounders.

Main Outcome Measures

Distribution of SFCT, NCI_EDI, and CVI in the healthy Japanese population and their characteristics.

Results

Age-sex standardized SFCT, NCI_EDI, and CVI were 291.2 μm, 0.653, and 66.88%, respectively. In both men and women, SFCT was associated negatively with age (P < 0.001) and NCI_EDI was associated positively with age (P < 0.001). Although both SFCT and NCI_EDI did not differ significantly between men and women overall (P = 0.87 and P = 0.21, respectively), among younger participants (35–50 years of age), men showed significantly greater SFCT than women (P < 0.001). Only in men was CVI associated positively with age (P < 0.001). In the multivariable analysis, SFCT was associated significantly with age, sex, AL, SE, and the interaction term of age and sex (P < 0.001). Independent of SFCT, NCI_EDI and CVI were associated significantly with age (P < 0.001).

Conclusions

We report normative Japanese SFCT, NCI_EDI, and CVI data using a large general Japanese cohort. The association analysis of SFCT with NCI_EDI and CVI suggested that younger individuals have a more lumen-rich choroid for their choroidal thickness than older individuals.

Choroidal Thickness and Volume Modifications Induced by Aerobic Exercise in Healthy Young Adults

INTRODUCTION

Our aim was to evaluate the changes in choroidal thickness (CT) and volume (CV) following aerobic physical exercise in healthy young adults.

METHODS

This study included 72 eyes from healthy volunteers between 22 and 37 years old. Using the International Physical Activity Questionnaire, total physical activity was computed. Measurements using an autorefractometer, ocular biometry, and spectral-domain optical coherence tomography using the Enhanced Depth Imaging protocol were taken. OCT was performed as a baseline measurement and after performing 10 min of dynamic physical exercise (3 and 10 min post-exercise). The choroidal layer was manually segmented, and the CT and CV in different areas from the Early Treatment Diabetic Retinopathy Study grid were obtained.

RESULTS

In healthy adults, at 3 min post-exercise, CT was higher in the subfoveal, the 3-mm nasal, and the 6-mm superior areas. Between 3 and 10 min post-exercise, the CT was reduced in all areas, and in some areas, the values were even smaller than the baseline measurements. The CV values showed changes after exercise similar to those of thickness. The total CV recovery after exercise was related to sex and physical activity level.

CONCLUSION

Individuals with higher physical activity habits had greater CV at rest than those with lower physical activity levels. During exercise, healthy young people adjust CT and CV. At 3 min post-exercise, CT and CV increase. Women and individuals with greater physical activity levels reduce their total CV more than others during recovery.