Variation Of Choroidal Thickness Research Articles

High correlated color temperature artificial lighting impairs retinal pigment epithelium integrity and chloride ion transport: A potential mechanism for choroidal thinning

Among the environmental factors contributing to myopia, the role of correlated color temperature (CCT) of ambient light emerges as a key element warranting in-depth investigation. The choroid, a highly vascularized and dynamic structure, often undergoes thinning during the progression of myopia, though the precise mechanism remains elusive. The retinal pigment epithelium (RPE), the outermost layer of the retina, plays a pivotal role in regulating the transport of ion and fluid between the subretinal space and the choroid. A hypothesis suggests that variations in choroidal thickness (ChT) may be modulated by transepithelial fluid movement across the RPE. Our experimental results demonstrate that high CCT illumination significantly compromised the integrity of tight junctions in the RPE and disrupted chloride ion transport. This functional impairment of the RPE may lead to a reduction in fluid transfer across the RPE, consequently resulting in choroidal thinning and potentially accelerating axial elongation. Our findings provide support for the crucial role of the RPE in regulating ChT. Furthermore, we emphasize the potential hazards posed by high CCT artificial illumination on the RPE, the choroid, and refractive development, underscoring the importance of developing eye-friendly artificial light sources to aid in the prevention and control of myopia.

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

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

Analysis of macula structural changes in Moyamoya disease using AI-assisted OCT

ObjectiveTo investigate macula structure thickness and volume changes in patients with moyamoya disease (MMD). MethodIn this cross-sectional study, we used artificial intelligence (AI) -assisted optical coherence tomography (OCT) to analyze the thickness and volume of macula in Moyamoya patients. ETDRS zoning divides the macula into nine different regions. In 15 patients with radial scanning OCT, the average thickness and volume of retina, RNFL, GCL, and choroid in these regions were measured. In 30 patients with radial or horizontal scanning OCT, based on the anatomical structure, the macula is divided into seven segments. Mean Sattler layer–choriocapillaris complex thickness (SLCCT), Haller layer thickness, and total choroidal thickness were measured for each segment using AI-assisted OCT. ResultsWe recruited 30 patients (59 eyes) with MMD. In the 15 patients (29 eyes) who underwent radial scanning OCT, no significant change in retina, RNFL, GCL, and choroidal thickness was identified between the two groups (p > 0.05). There was no significant change in retina, RNFL, or choroidal volume between the two groups in different ETDRS macula regions (p > 0.05). The GCL volume in the macula's inner ring nasal portion (IN) was significantly lower. SLCCTs were considerably reduced in six macula regions in moyamoya groups (p < 0.05). There was no statistically significant change in Haller layer thickness. Only the nasal perifovea (PE_N) exhibited a significant variation in choroidal thickness. The Moyamoya group showed reduced choroidal thickness in PE_N segment. ConclusionIn patients with MMD, there is thinning of the Sattler layer–choriocapillaris complex in the choroid.

Correlations between subfoveal choroidal thickness, macular thickness, and visual outcome in neovascular age-related macular degeneration using swept source OCT: insights from intravitreal aflibercept treatment

BackgroundAge-related macular degeneration (AMD) is a leading cause of visual impairment among individuals aged 50 and above, often resulting in irreversible vision loss (1). Currently, antiangiogenic therapy is the primary treatment approach for neovascular AMD (2). The choroid has gained significant attention in recent years due to its involvement in various ocular pathologies (7). The objective of this study was to evaluate visual acuity and correlate pre-treatment variables, such as foveal thickness and choroidal thickness, with post-treatment outcomes.Materials and MethodsThis study was designed as a prospective interventional study to investigate the changes in choroidal and macular thickness in patients with neovascular AMD who received intravitreal aflibercept injections. The study utilized medical records and employed Swept Source Optical Coherence Tomography (OCT-SS) for evaluation. The data was collected from patients treated in Presidente Prudente, Brazil, during a three-month load dose period.ResultsThe best-corrected mean visual acuity significantly improved from 1.0 logarithm of the minimum resolution angle (logMAR) units to 0.55 logMAR after treatment with aflibercept (p < 0.001). Patients undergoing treatment exhibited a significant decrease in average macular thickness from 323 μm to 232 μm (p = 0.001), as well as a reduction in choroidal thickness from 206 μm to 172 μm (p = 0.031), while maintaining intraocular pressure within the normal range (p = 0.719) without significant variation. Statistically significant associations were found between the difference in pre- and post-treatment choroidal thickness and the pretreatment values of macular thickness (p = 0.005) and choroidal thickness (p = 0.013). There was also a statistically significant correlation between the difference in pre- and post-treatment macular thickness and the pretreatment macular thickness value (p < 0.001).ConclusionIn this study, aflibercept exhibited remarkable effectiveness in reducing macular and choroidal thickness, as evaluated using OCT-SS, and significantly improved visual acuity in patients with neovascular AMD. The assessment of both choroidal and macular changes, as well as their correlations, can provide valuable insights for clinicians, enabling them to make well-informed therapeutic decisions and effectively monitor treatment outcomes. Notably, this study contributes to the existing body of literature as the first to establish a correlation between pretreatment foveal thickness, variation in choroidal thickness, and post-treatment choroidal thickness.

Variation of choroidal thickness during the waking period over three consecutive days in different degrees of myopia and emmetropia using optical coherence tomography.

To investigate the diurnal variation in subfoveal choroidal thickness (SFCT) during the waking period over three consecutive days in different degrees of myopia and emmetropia. A total of 60 adult volunteers were grouped into low, moderate, high myopia, and emmetropia subgroups. SFCT, axial length (AL), anterior chamber depth (ACD), and intraocular pressure (IOP) were measured every 2 h from 8 AM to 8 PM for three successive days. The mean values of daily change amplitude were 3.18 mmHg (IOP), 0.05 mm (AL), 0.17 mm (ACD), and 13.51 μm (SFCT). The values of AL and ACD increased simultaneously with spherical equivalent refraction (SER), but SFCT was the opposite. IOP had a diurnal variation, and there was no difference among the four groups. AL of the high myopia group, ACD of the emmetropia group, and SFCT of each myopia group had diurnal variation over three consecutive days. AL had a high mean value at noon every day, and SFCT had a low mean value at noon every day. The choroid thickness of subjects with different degrees of myopia had a significant diurnal variation. The change of diurnal variation between emmetropic and myopic subjects may be one of the causes of myopia.

Analysis of choroidal thickness in juvenile systemic lupus erythematosus and its correlation with laboratory tests

BackgroundThe aim of this study is to investigate the alterations of choroidal thickness (CT) in juvenile systemic lupus erythematosus (JSLE) using enhanced depth imaging optical coherence tomography (EDI-OCT). We also aimed to assess whether CT parameters correlated with systemic health status in JSLE patients.MethodsJSLE patients and age- and sex-matched healthy subjects were recruited. A detailed ophthalmological examination was applied to all participants. CT measurements were acquired in the macular region using EDI-OCT. Moreover, a spectrum of laboratory tests was examined to evaluate the systemic conditions, and the Th1/Th2/Th17/Treg cytokine profiles in the peripheral blood were also analyzed in JSLE group.ResultsA total of 45 JSLE patients with no visual impairment and 50 healthy individuals were enrolled in the study. CT values in the macular region were decreased in JSLE patients when compared with healthy controls, even adjusting for age, axial length and refraction. There were no significant correlations between CT and cumulative dose of hydroxychloroquine or duration of hydroxychloroquine use (all P > 0.05). The average macular, temporal and subfoveal CT in JSLE group was negatively correlated with IL-6 and IL-10 (all P < 0.05), but had no significant correlations with other laboratory results (all P > 0.05).ConclusionsJSLE patients without ocular involvement may have significant variations in choroidal thickness at the macular area. Choroidal alterations might be associated with the systemic cytokine profiles in JSLE.

Choroidal thickness in exudative age‐related macular degeneration and influence of intravitreal anti‐VEGF treatment

AbstractPurpose: To evaluate choroidal thickness progression over time in patients with exudative age‐related macular degeneration (AMD) and its relation with anti‐VEGF treatment.Methods: Retrospective observational case series. Study group included patients observed between January 2022 and April 2022 at Ophthalmology Department of Hospital de São João, Porto, Portugal, diagnosed with bilateral exudative AMD (eAMD) or unilateral eAMD and intermediate AMD (iAMD) in contralateral eye with a minimum follow up of 2 years. Subfoveal choroidal thickness was measured in each of the studied eyes using cross‐sectional spectral domain optical coherence tomography images, obtained every year during follow‐up period. Statistical analysis was performed to correlate choroidal thickness variation with number of intravitreal injections.Results: 66 eyes with eAMD and 20 eyes with iAMD from 43 patients (mean age, 81.15 ± 6.10 years) followed during 7.15 ± 2.65 years. eAMD eyes were treated with 54.83 (range 6–100 injections) anti‐VEGF intravitreal injections. Choroidal thickness of eyes with eAMD decreased 56.65 ± 11.66 μm over the follow up period (p &lt; 0.001) at a rate of 6.49 μm per year. Choroidal thickness of eyes with iAMD decreased 29.30 ± 22.07 μm over the follow up period (p &gt; 0.2) at a slower rate of 0.68 μm per year. In the subgroup of patients with unilateral eAMD and contralateral iAMD (n = 20), choroidal thickness changes were significantly different between the two eyes (p &lt; 0.001). Number of intravitreal injections correlated inversely with choroidal thickness in eyes with eAMD (r = −0.232; p &lt; 0.001).Conclusions: A significant thinning of choroid in eyes with eAMD and an inverse correlation with number of anti‐VEGF injections was observed, suggesting the influence of prolonged anti‐VEGF suppression on choroidal thickness decrease. Further studies with a higher number of eyes are needed to validate our results.

Retinal and choroidal vasoreactivity in central serous chorioretinopathy.

This study aims to investigate retinal and choroidal vascular reactivity to carbogen in central serous chorioretinopathy (CSC) patients. An experimental pilot study including 68 eyes from 20 CSC patients and 14 age and sex-matched controls was performed. The participants inhaled carbogen (5% CO2 + 95% O2) for 2min through a high-concentration disposable mask. A 30° disc-centered fundus imaging using infra-red (IR) and macular spectral domain optical coherence tomography (SD-OCT) using the enhanced depth imaging (EDI) technique was performed, both at baseline and after a 2-min gas exposure. A parametric model fitting-based approach for automatic retinal blood vessel caliber estimation was used to assess the mean variation in both arterial and venous vasculature. Choroidal thickness was measured in two different ways: the subfoveal choroidal thickness (SFCT) was calculated using a manual caliper and the mean central choroidal thickness (MCCT) was assessed using an automatic software. No significant differences were detected in baseline hemodynamic parameters between both groups. A significant positive correlation was found between the participants' age and arterial diameter variation (p < 0.001, r = 0.447), meaning that younger participants presented a more vasoconstrictive response (negative variation) than older ones. No significant differences were detected in the vasoreactive response between CSC and controls for both arterial and venous vessels (p = 0.63 and p = 0.85, respectively). Although the vascular reactivity was not related to the activity of CSC, it was related to the time of disease, for both the arterial (p = 0.02, r = 0.381) and venous (p = 0.001, r = 0.530) beds. SFCT and MCCT were highly correlated (r = 0.830, p < 0.001). Both SFCT and MCCT significantly increased in CSC patients (p < 0.001 and p < 0.001) but not in controls (p = 0.059 and 0.247). A significant negative correlation between CSC patients' age and MCCT variation (r = - 0.340, p = 0.049) was detected. In CSC patients, the choroidal thickness variation was not related to the activity state, time of disease, or previous photodynamic treatment. Vasoreactivity to carbogen was similar in the retinal vessels but significantly higher in the choroidal vessels of CSC patients when compared to controls, strengthening the hypothesis of a choroidal regulation dysfunction in this pathology.

Choroidal Thickness Increase after Subliminal Transscleral Cyclophotocoagulation.

Background: The purpose of this study is to estimate the success rate of subliminal transscleral cyclophotocoagulation for refractory glaucoma and to determine the correlation between the decrease in intraocular pressure and the variation in choroidal thickness. Methods: A pre–post study was conducted over a period of 3 years, including 81 eyes from 67 patients with different types of drug-refractory glaucoma who underwent subliminal transscleral cyclophotocoagulation. The variables included best-corrected visual acuity, intraocular pressure and choroidal thickness. Results: We observed the following success rates (defined as IOP < 21 mmHg): 80% at 1 month (65 patients), 74% at 3 months (60 patients), 64% at 6 months (52 patients) and 50.6% at 1 year (41 patients). A strong correlation was noted between the decrease in intraocular pressure and the increase in the average choroidal thickness at 1 year (318.42 µm) compared to the average preoperative thickness (291.78 µm). A correlation of increased choroidal thickness at 1-month with the success rate of the procedure was also observed. Conclusions: We observed a statistically significant correlation between the success rate, decrease in intraocular pressure and choroidal thickness. The correlation of increased choroidal thickness at 1-month with the success rate of the procedure could be used clinically as a predictive factor for the final outcome of patients. Further experimental research is warranted to determine whether the increase in choroidal thickness after subliminal transscleral cyclophotocoagulation is indeed evidence of increased uveoscleral drainage.

Choroidal and retinal thickness variations in ocular albinism.

Purpose:To study the retinal and choroidal thickness variations on enhanced depth imaging optical coherence tomography scans in ocular albinism (OA) and compare with age-matched healthy subjects.Methods: This retrospective observational study had 48 eyes of 24 patients diagnosed clinically as OA and age, sex, and axial length-matched control healthy subjects. All patients underwent detailed ophthalmic examination and a single-line horizontal-raster enhanced depth imaging – optical coherence tomography scan (Spectralis, Heidelberg Engineering). Retinal and choroidal thickness was measured, compared, and analyzed between the two groups. Mann–Whitney U test was used for analysis between the two groups. P < 0.05 was considered significant.Results: The mean age was 28.3 ± 11.6 and 29.9 ± 10.6 years in the OA group and control group, respectively. Spherical equivalents ranged from −8.5D to +10.5D in the OA group and from −8.0D to +10.0D in the control group. The mean axial length between the two groups (P = 0.652) were comparable. The average retinal thickness (272 ± 34.3 vs. 213 ± 13.8 mm; P < 0.001) was greater in the OA group as compared to controls. The mean choroidal thickness (184 ± 78.4 vs. 287 ± 46.4 mm; P < 0.001) was significantly thinner in the OA group.Conclusion: Acquisition of OCT scans in OA can be challenging. This study showed that the subfoveal retinal thickness and choroidal thickness measured across the scans were significantly different in the OA group compared to controls. In the future, more studies are required to evaluate the role of the choroid and its relationship to emmetropization in albinism.

Regional Distribution of Choroidal Thickness and Diurnal Variation in Choroidal Thickness and Axial Length in Young Adults.

PurposeTo examine the regional distribution of choroidal thickness (ChT) and the diurnal variation in ChT and axial length (AL) over a wide range of myopic refractive error.MethodsChT was measured in thirty-four healthy young adults (age mean ± SD: 25.2 ± 2.8, range: 18–35 years) using spectral-domain optical coherence tomography and AL using an IOL-Master 500. Participants were divided into three refractive groups: emmetropes, myopes, and high myopes. We evaluated ChT in macular (foveal, parafovea, and perifovea) and peripheral regions (6-mm from the foveal pit) in four quadrants (superior, temporal, inferior, and nasal). To assess the diurnal variation, three measurement sessions of ChT and AL were taken at 8 AM, 12 PM, 4 PM.ResultsChT thins progressively towards the periphery. Superior and nasal quadrants exhibited the thickest (277 ± 73 µm) and thinnest (218 ± 89 µm) choroid, respectively. Higher myopic eyes showed an overall thinner choroid (237 ± 48 µm) compared to myopic eyes (264 ± 78 µm) (P < 0.05). Higher myopes exhibited a significant choroidal thinning in all quadrants except in the temporal quadrant (all p < 0.05). Both ChT and AL underwent a significant diurnal variation (p < 0.05). The ChT and AL diurnal variation amplitudes in higher myopes were significantly reduced (ChT: 14.6 ± 11, AL: 14.5 ± 13 µm), compared to those in emmetropes (ChT: 21.4 ± 15, AL: 21.3 ± 8.5 µm) and myopes (ChT: 19 ± 17, AL: 19 ± 9.7 µm). Diurnal variation amplitude in ChT did not differ significantly across quadrants and choroidal eccentricity regions (p > 0.05).ConclusionChT distribution varies based on quadrant and eccentricity; superior choroid exhibited the thickest, and nasal showed the thinnest choroid. Higher myopes experience a reduced diurnal variation in ChT and AL.

Wide-field choroidal thickness and vascularity index in myopes and emmetropes.

To study regional variations in choroidal thickness (CT), luminal thickness and stromal thickness of the choroid, and choroidal vascularity index (CVI) in low myopic and emmetropic eyes using wide-field optical coherence tomography (OCT). Sixty-nine healthy young adults between 20 and 38years of age participated in this study, including 40low myopes (mean ± SD spherical equivalent (MSE) refractive error: -3.00±1.39 D, range: -6.00 to -0.62 D) and 29 emmetropes (MSE: -0.05±0.09 D, range: -0.25 to +0.12 D). Wide-field CT, luminal thickness, stromal thickness and CVI were measured across five eccentricities (fovea, parafovea, perifovea; near-periphery and periphery) and four quadrants (nasal, temporal, inferior and superior), in vertical and horizontal meridians, while controlling for a range of extraneous factors potentially influencing the CT. Custom-written software was used to segment and binarize the OCT images. Wide-field CT, luminal thickness and stromal thickness, averaged across all participants, exhibited significant topographical variation, with the foveal (379±8µm, 200±4µm, 179±4µm, respectively) and peripheral (275±8µm, 161±4µm, 114±4µm, respectively) regions presenting the thickest and thinnest regions (all p<0.001). Wide-field CVI showed a progressively higher percentage (greater vascularity) with increasing eccentricity from the fovea towards the periphery (p<0.001). Macular CT and stromal choroidal thickness were significantly thinner in myopes compared to emmetropes (p<0.05). Myopes (55.7±0.3%) showed a slightly higher CVI compared with emmetropes (54.4±0.4%) (p<0.05). Low myopia in young adults was associated with significant choroidal thinning across the macular, but not extramacular regions, with this decrease in choroidal thickness mostly attributed to thinning in the stromal component of the choroid, rather than the luminal (vascular) component.

The influence of the choroid on the onset and development of myopia: from perspectives of choroidal thickness and blood flow.

Myopia is the most common type of refractive errors characterized by excessive elongation of the ocular globe. With the increasing prevalence of myopia, improved knowledge of factors involved in myopia development is of particular importance. There are growing evidence suggesting that the choroid plays an important role in the regulation of eye growth and the development of myopia. Studies have demonstrated that thinning choroid is a structural feature of myopia, with a negative correlation between choroidal thickness and axial length, suggesting that the change in choroidal thickness may be a predictive biomarker for long-term changes in ocular elongation. Given the fact that the choroid is primarily a vascular structure capable of rapidly changing blood flow, variations of choroidal thickness might be primarily caused by changes in choroidal blood flow. Considering that hypoxia is associated with myopia and choroidal blood flow is the main source of oxygen and nourishment supply, apart from the effect on myopia possibly by changing choroidal thickness, decreasing choroidal blood flow may contribute to scleral ischaemia and hypoxia, resulting in alterations in the scleral structure and thus leading to myopia. This review aims to provide an overview of recent work exploring the influence of the choroid on myopia from perspectives of choroidal thickness and blood flow, which may present new predictive indicators for the onset of myopia and new targets for the development of novel therapeutic approaches for myopia.

Choroidal structural changes in different intermediate AMD patterns.

To report variation of choroidal thickness (CT) and choroidal vascularity index (CVI) in subjects with drusen and subjects with reticular pseudodrusen (RPD) compared with healthy individuals using the Spectral-domain (SD)-Optical Coherence Tomography with enhanced depth imaging (EDI) system. A prospective, observational, cross-sectional study. Eighty-four participants. The patients were imaged using the Heidelberg Spectralis device (Heidelberg Engineering, Heidelberg, Germany) with EDI mode. EDI-OCT images were exported and then imported into image analysis ImageJ software (National Institutes of Health, Bethesda) and a semiautomated algorithm was used for subsequent quantitative analysis. This study evaluated two choroidal parameters: (i) choroidal thickness (CT); (ii) choroidal vascularity index (CVI). CT analysis was performed in three different regions: (i) foveal region, (ii) parafoveal region; (iii) perifoveal region. All the analyzed regions were significantly decreased in RPD pattern, as compared with both the drusen group (p < .005) and healthy eyes (p < .005). CVI was significantly decreased in the RPD pattern, as compared with healthy eyes (p < 0.001). However, the drusenoid pattern did not have statistical significance in comparison with the control group suggesting the lower incidence of this pattern on choroidal vasculopathy. We report CT and CVI difference in RPD and drusen eyes. The RPD pattern seems to be a consequence of an alteration in the choroidal vascularity resulting in severe ischemia and excessive hypoxia inducing an increased risk of late AMD compared to the drusenoid pattern.

Topographic Variations of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography.

PurposeTo assess topographic variations of choroidal thickness (CT) in the fovea and beyond in healthy eyes.MethodsThis cross-sectional study included healthy subjects ≤ 55 years of age with axial lengths (22–26 mm) and refractive error margins (–4D, +4D) in normal ranges. Images were acquired using swept-source optical coherence tomography angiography (OCT-A). Corneal thickness (CT) maps from 12 × 12-mm radial scans and 9 × 9-mm OCT-A B-scans were analyzed.ResultsThe study included 64 eyes of 33 subjects (mean age, 37 years). Mean CT was >300 µm in all locations except the nasal outer macula. The subfoveal CT was >395 µm in 30% of cases; in 38.7% of cases, >50% of the CT map was thicker than 395 µm. The mean thickest choroidal point was 395.2 µm (range, 164–548 µm), located superior and temporal to the macula in 72.2% of cases and subfoveally in 1.8% of cases. The CT pattern was symmetrical (58%) or asymmetrical (42%) along a horizontal axis correlating with choroidal vein distribution. Half of the asymmetrical patterns were thicker in the inferior quadrants, with an oblique temporal watershed of venous drainage, and the other half were thicker superiorly. The mean vascularity index was ∼75% regardless of the mean CT.ConclusionsOne-third of healthy eyes of patients younger than age 55 had a thick choroid (>395 µm). In these normal eyes, the thickest choroidal point was not subfoveal, CT symmetry above and below the fovea depended on choroidal vein distribution, and choroidal vascularity index was independent from CT. No patients demonstrated fundus autofluorescence abnormalities, and the choriocapillaris remained visible even in thick choroids. These features could be interesting when differentiating normal versus pathological states.

Daily axial length and choroidal thickness variations in young adults: Associations with light exposure and longitudinal axial length and choroid changes

Evidence from animal studies suggests that the eye's natural diurnal rhythms can be disrupted by altering the light/dark cycle or during refractive error development. Although diurnal variations in axial length (AL) and choroidal thickness are well documented in human eyes, the relationship between ambient light exposure, refractive error progression and diurnal AL and choroidal thickness variations is not well understood. Therefore we examined the association between objective ambient light exposure and daily variations in AL and subfoveal choroidal thickness (SFCT), along with longer-term changes in AL and SFCT over 12 months. Thirty-four young adult emmetropes and myopes had their daily variations (measurements ~ every 3 h from 9 a.m. to 9 p.m.) in AL and SFCT assessed on a weekday and weekend in winter and then six months later in summer. Participants then returned six months later for a single measurement session to determine the longer-term change in AL and SFCT. Personal ambient light exposure was captured in winter and summer using wrist-worn light sensors (Actiwatch-2) worn for 14 days over the same period of time when the diurnal measurements were collected. Linear mixed model analyses revealed significant daily variations in AL and SFCT (each p < 0.05). The mean daily peak to trough difference (amplitude) in AL was significantly greater in myopes (0.020 mm; 95% CI: 0.014–0.026 mm) compared to emmetropes (0.010 mm; 95% CI: 0.005–0.015 mm) (p < 0.01), but the SFCT variations were not significantly different between the refractive groups (p = 0.45). Daily variations in AL were negatively associated with the daily SFCT variations (r = −0.603, p < 0.001). Correlation analyses indicated that the amplitude of daily AL variations was negatively associated with the daily time exposed to bright light (r = −0.511, p = 0.002) and positively associated with the longitudinal AL changes over 12 months (r = 0.381, p = 0.04). There was an inverse association between the longer-term changes in AL and SFCT (r = −0.352, p = 0.002). The daily ocular diurnal variations were not significantly different between weekdays and weekends, or between summer and winter (each p > 0.05). In summary, diurnal variations in AL were higher in amplitude in myopes compared to emmetropes and were also associated with longitudinal changes in AL. These findings suggest that diurnal variations may be associated with longer-term axial eye growth. Time spent in bright light also significantly influenced the amplitude of daily AL variations, with more time exposed to bright light associated with a smaller amplitude of diurnal AL change. Choroidal thickness exhibited an inverse association with the AL changes, implying a potential role for the choroid in eye growth.

Wide-field choroidal thickness in myopes and emmetropes

There is a paucity of knowledge regarding the normal in-vivo thickness of the choroid beyond the macula (~17°). In this study, the choroidal thickness of 27 healthy young adults was examined across the macular (the central 5 mm including the fovea, parafovea, and perifovea) and extra-macular (a 5–14 mm annulus including the near-periphery and periphery) regions using wide-field optical coherence tomography, and compared between emmetropes (n = 14) and myopes (n = 13). The choroid progressively thinned beyond the parafovea (350 ± 86 µm) towards the periphery (264 ± 44 µm), and was thickest superiorly (355 ± 76 µm) and thinnest nasally (290 ± 79 µm). Choroidal thickness also varied with refractive error; myopes exhibited a thinner choroid than emmetropes in the macular region (311 ± 88 vs. 383 ± 66 µm), however, this difference diminished towards the periphery (251 ± 48 vs. 277 ± 37 µm). Meridional variations in choroidal thickness were not different between myopes and emmetropes. In conclusion, the choroid was thickest within the perifovea; thinned substantially towards the periphery, and exhibited the minimum and maximum peripheral thinning superiorly and nasally across a 55° region respectively. Choroidal thinning associated with myopia was more pronounced in the macular than extra-macular regions.

Diurnal Variation of Choroidal Thickness in Primary Open-angle Glaucoma.

To investigate, in primary open-angle glaucoma (POAG) and healthy subjects, the pattern and magnitude of diurnal variation in macular choroidal thickness (mCT). A prospective study was conducted on Koreans comprising 21 patients with POAG and 17 healthy subjects. All underwent mCT, systemic blood pressure (BP), and intraocular pressure measurements during the daytime at 5 time points (8 AM, 11 AM, 2 PM, 5 PM, and 8 PM). The mCT was determined at 5 sites using swept-source optical coherence tomography. In the healthy subjects, the mean mCT was 233.63±50.98 μm at 8 AM, which then decreased gradually to 2 PM (206.02±45.91, P=0.015) and increased again in the evening (8 PM; 228.12±51.69, P=0.030). The mean mCT in the POAG patients at 8 AM, 246.50±48.94 μm, also decreased to 226.77±51.48 at 2 PM (P=0.027) but did not increase in the evening (229.07±50.87; P=0.566). However, the overall diurnal variation of mean mCT was not statistically significant in either group (P=0.179 and 0.164, respectively). The systolic BP, diastolic BP, and mean ocular perfusion pressure of the POAG had the peak value at 8 AM and the trough value at 8 PM (P=0.001, 0.002, and <0.001). The mCT in the POAG patients did not increase in the evening relative to the healthy subjects' pattern. However, the diurnal mCT values measured in the healthy subjects and POAG patients were not statistically significant.

Macular and Peripapillary Choroidal Thickness in Patients With Keratoconus.

To investigate and compare macular and peripapillary choroidal thickness and profiles of patients with keratoconus and age-matched controls and correlate subfoveal choroidal thickness with keratoconus severity. This was a prospective, observational, cross-sectional study comprising 45 keratoconus patients and 56 healthy controls. Choroidal thicknesses at the fovea and at 750-μm intervals from the fovea to 1.5 mm in the nasal and temporal directions were measured by spectral-domain optical coherence tomography. Peripapillary choroidal thickness was measured at six segments along the circle scan. Mean age did not differ between the patients with keratoconus and controls (24.5 ± 7.2 vs. 22.5 ± 7.4 years, P = .170). Mean subfoveal choroidal thickness was higher in the keratoconus group (427.48 μm ± 78.51 μm) than in controls (351.03 μm ± 99.08 μm; P < .001). Mean subfoveal choroidal thickness did not differ between mild and severe keratoconus (437.82 ± 53.4 vs. 418.87 ± 113.9 μm; P = .660). In the macular area, choroidal thickness was lower at 1.5 mm nasal to the fovea (P < .0001) in both groups. The choroid was thinner at 0.75 mm temporal to the fovea than under the fovea in the keratoconus group (P < .001). The peripapillary choroid was thinner in the inferonasal and inferotemporal segments than in the other segments in both groups (P < .001). The peripapillary choroid was thinner in the inferonasal segment than in the inferotemporal segment in the keratoconus group (P = .018). Subfoveal choroidal thickening is observed in keratoconus eyes. The pathophysiological role of choroidal thickness variations should be considered in the natural history of keratoconus. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:664-673.].

Choroidal Thickness in Chinese Children Aged 8 to 11 Years with Mild and Moderate Myopia.

Purpose To investigate macular choroidal thickness (CT), topographical variation, and associations between subfoveal choroidal thickness (SFCT) and age, gender, spherical equivalent (SE), and axial length (AL) in Chinese healthy mild and moderate myopia children aged 8 to 11 years. Methods One hundred twenty eyes from 120 healthy children were studied. Children were divided into mild and moderate myopia groups. AL and CT were evaluated. CTs were measured at the fovea, and 1 mm, 2 mm, and 3 mm nasal, temporal, superior, and inferior to the fovea. Results SFCT was 252.80 ± 46.95 µm in the whole population. AL was shorter in the mild myopia group (24.18 ± 0.69 mm) than in the moderate myopia group (24.97 ± 0.68 mm, P < 0.001), and SFCT was thicker in the mild myopia group (262.00 ± 40.57 µm) than in the moderate myopia group (236.00 ± 55.08 µm, P=0.005). The topographical variation was similar in refraction groups. CTs nasal to the fovea thinned gradually and were all significantly thinner than SFCT. CTs in the other three directions gradually thickened and peaked at locations of 2 mm to the fovea. Then, CTs thinned at 3 mm to the fovea. The thickest choroid is located temporal to the fovea. There were significant negative correlations between AL and SFCT in the mild myopia group and the whole population. No other correlations were found. Conclusions The topographical variations of choroidal thickness were similar in mild and moderate myopia groups with the thickest locations temporal to the fovea. SFCT was relatively stable in children in narrow range of age and refractive error.