The Differential Contribution of Macular Pigments and Foveal Anatomy to the Perception of Maxwell's Spot and Haidinger's Brushes

The relationship of macular pigments and foveal anatomy to the perception of Maxwell's spot (MS) and Haidinger's brushes (HB) entoptic phenomena were investigated. Dual-wavelength-autofluorescence and OCT were used to define macular pigment density and foveal anatomy in 52 eyes. MS was generated by alternating unpolarized red/blue and red/green uniform field illumination. HB was generated by alternating the linear polarization axis of a uniform blue field. In Experiment 1, horizontal widths of MS and HB were measured using a micrometer system and compared with macular pigment densities and OCT-defined morphometry. MS radius (mean 1.4°) was significantly less than HB radius (mean 1.6°), with the spatial extent of both phenomena falling between the boundaries of the foveola and foveal pit. Multiple regression showed MS and HB radii to be significantly associated with the macular pigment spatial profile radius. HB radius, but not MS radius, was also significantly associated with foveolar morphometry. Experiment 2 compared perceptual profiles of MS with macular pigment distribution patterns and demonstrated close agreement. The size and appearance of MS is a direct indicator of macular pigment density and distribution. Measures of HB radii are less specific, with dependence on both macular pigment density and foveal structure.

Macular thickness varies with age-related macular degeneration genetic risk variants in the UK Biobank cohort

To evaluate the influence AMD risk genomic variants have on macular thickness in the normal population. UK Biobank participants with no significant ocular history were included using the UK Biobank Resource (project 2112). Spectral-domain optical coherence tomography (SD-OCT) images were taken and segmented to define retinal layers. The influence of AMD risk single-nucleotide polymorphisms (SNP) on retinal layer thickness was analysed. AMD risk associated SNPs were strongly associated with outer-retinal layer thickness. The inner-segment outer segment (ISOS)-retinal pigment epithelium (RPE) thickness measurement, representing photoreceptor outer segments was most significantly associated with the cumulative polygenic risk score, composed of 33 AMD-associated variants, resulting in a decreased thickness (p = 1.37 × 10-67). Gene-gene interactions involving the NPLOC4-TSPAN10 SNP rs6565597 were associated with significant changes in outer retinal thickness. Thickness of outer retinal layers is highly associated with the presence of risk AMD SNPs. Specifically, the ISOS-RPE measurement. Changes to ISOS-RPE thickness are seen in clinically normal individuals with AMD risk SNPs suggesting structural changes occur at the macula prior to the onset of disease symptoms or overt clinical signs.

A 12-week, randomized, double-blind, placebo-controlled study assessing the efficacy of EGHB010, a standardized extract of Paeoniae radix and Glycyrrhizae radix, in patients with early age-related macular degeneration

BACKGROUND

EGHB010, a standardized extract of Paeoniae radix and Glycyrrhizae radix, inhibits choroidal neovascularization. The aim of this study is to evaluate the efficacy and safety of EGHB010 on early age-related macular degeneration (AMD) progression inhibition.

METHODS

The study was designed as a randomized, double-blind, single-center, placebo-controlled study. Subjects were 50 years of age or older, and early AMD satisfied the criteria of more than 15 small (<63 µm) drusen, less than 20 intermediate (≥63, <125 µm) drusen, or pigment abnormalities. For 12 weeks, the treatment group received EGHB010 and the control received the placebo. The main outcomes were changes in macular pigment optical density (MPOD), central macular thickness (CMT), and central choroidal thickness (CCT). Subgroup analysis was performed on subjects with MPOD <0.75 at baseline.

RESULTS

Forty-eight subjects out of 94 were assigned to the treatment group, and 46 to the control group. At 12 weeks, mean MPOD of the treatment group increased by 0.04±0.27 (P=0.2730), and that of the control group decreased by 0.03±0.21 (P=0.7240), but there was no significant difference between the two groups (P=0.1234). There were no significant differences between the two groups in mean CMT and CCT (P=0.6718 and 0.6608, respectively). In subgroup analysis, there were 39 subjects with MPOD <0.75 in the treatment group and 36 in the control. Mean MPOD of the treatment group significantly increased by 0.09±0.25 (P=0.0218), and there was a significant difference in mean MPOD at 12 weeks between the two groups (P=0.0248). Adverse reactions were similar in both groups, and no subjects had serious adverse events.

CONCLUSIONS

EGHB010 is expected to increase MPOD when administered to subjects with MPOD <0.75. EGHB010 is worth considering as a substance that inhibits the progression of early AMD.

Foveal macular pigment dip in offspring of age-related macular degeneration patients is inversely associated with omega-3 index

Background

Offspring of parent(s) with age-related macular degeneration (AMD) have a 45% lifetime risk of developing the disease. High foveal macular pigment optical density (MPOD) is protective, whereas individuals with a “foveal macular pigment dip” (FMPD) are at increased risk. Shortage of the dietary carotenoids lutein, zeaxanthin as well as fish consumption are reported AMD risk factors. This Early Biomarkers of AMD (EBAMD) study evaluates serum factors that protect foveal MPOD architecture in Caucasian offspring of parent(s) with AMD.

Methods

N = 130 subjects [mean (SD) age 62.8 (8.6) years; 36/94 male/female] were recruited from Scripps Health/ Scripps Memorial Hospital/ Scripps Mericos Eye Institute between 2012 and 2017. Macula pigment 3D topography was evaluated using specular reflectance. Buccal genetic cheek swab, circulating serum dietary carotenoids and long-term RBC omega-3 fatty acid status, as well as common secondary clinical structural and vision function parameters were obtained.

Results

41 % of offspring of AMD parent(s) presented with FMPD. These offspring were about 4 years younger than those without FMPD (controls; P = 0.012) and had thinner foveas (P = 0.010). There were no differences in gender, BMI, % body fat, visual acuity or contrast sensitivity between those with and without FMPD. % RBC membrane docosahexaenoic acid (DHA) was reduced in FMPD offspring vs. control offspring (P = 0.04). The Omega-3 Index was significantly decreased in the FMPD group (P = 0.03).

Conclusions

The percentage of FMPD in AMD offspring is nearly twice that reported for the general population in the scientific literature. Offspring presenting FMPD had similar AMD genetic risk, but significantly reduced % RBC membrane omega-3 fatty acids and thinner foveas compared with those without FMPD. Our data supports the importance of ‘essential fatty’ acids as an independent AMD risk factor.

Local Abundance of Macular Xanthophyll Pigment Is Associated with Rod- and Cone-Mediated Vision in Aging and Age-Related Macular Degeneration

Purpose

We assessed the association between the abundance of macular xanthophyll carotenoid pigment using dual-wavelength autofluorescence and multimodal vision testing including rod-mediated dark adaptation (RMDA), a measure of retinoid re-supply, in adults ≥60 years old with and without age-related macular degeneration (AMD).

Methods

AMD severity was determined using the nine-step Age-Related Eye Disease Study grading. Tests probed cones (best-corrected visual acuity, contrast sensitivity), cones and rods (low-luminance visual acuity, low-luminance deficit, mesopic light sensitivity), or rods only (scotopic light sensitivity, RMDA). Signal attenuation by macular pigment optical density (MPOD) was estimated using a ratio of blue and green autofluorescence signal to yield mean MPOD in a 1°-diameter fovea-centered disk, mean MPOD in a 2°-diameter disk centered on a perifoveal RMDA test location, and macular pigment optical volume (MPOV, or integrated MPOD) in a 4°-diameter fovea-centered disk. Age-adjusted associations between vision and imaging measures were determined.

Results

In 88 eyes of 88 subjects (age, 74.9 ± 5.8 years) with normal eyes (n = 32), early AMD (n = 23), or intermediate AMD (n = 33), foveal and perifoveal MPOD and MPOV were higher in the AMD eyes than in the normal eyes. At the RMDA test location, higher MPOD was unrelated to AMD severity but was associated with faster RMDA.

Conclusions

In older adults with and without AMD, higher macular xanthophyll concentrations are associated with better best-corrected visual acuity and RMDA. Data are consistent with a model of cone resilience and rod vulnerability in aging and AMD and can be further explored in a larger sample study.

Lutein Supplementation for Eye Diseases

Lutein is one of the few xanthophyll carotenoids that is found in high concentration in the macula of human retina. As de novo synthesis of lutein within the human body is impossible, lutein can only be obtained from diet. It is a natural substance abundant in egg yolk and dark green leafy vegetables. Many basic and clinical studies have reported lutein's anti-oxidative and anti-inflammatory properties in the eye, suggesting its beneficial effects on protection and alleviation of ocular diseases such as age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, myopia, and cataract. Most importantly, lutein is categorized as Generally Regarded as Safe (GRAS), posing minimal side-effects upon long term consumption. In this review, we will discuss the chemical structure and properties of lutein as well as its application and safety as a nutritional supplement. Finally, the effects of lutein consumption on the aforementioned eye diseases will be reviewed.

Comparison of Macular Pigment Optical Density in Glaucoma Patients and Healthy Subjects - A Prospective Diagnostic Study

Purpose

To evaluate the relationship between macular pigment optical density (MPOD) and glaucoma.

Methods

Forty-three patients with an established glaucoma diagnosis (25 females, 18 males, mean age 70 (range 34–84)) and 43 healthy controls (28 females, 15 males, mean age 62 (range 30–87)) were included in this prospective diagnostic case-control study. All subjects underwent detailed eye examination including ophthalmoscopy, best-corrected visual acuity, biomicroscopy, measurement of the axial length of the eye, objective refraction, lens status, central foveal thickness on spectral-domain optical coherence tomography (SD-OCT). In all glaucoma patients, a visual field assessment and a measurement of the retinal nerve fibre layer (RNFL) on SD-OCT were done. MPOD was determined using the macula pigment module of the Spectralis HRA+OCT (Heidelberg Engineering GmbH, Heidelberg, Germany) at 0.51°, 1.02° and 1.99° retinal eccentricity using two-wavelength autofluorescence imaging.

Results

In the glaucoma group, the median of the visual field mean defect was 5.1 db (quartiles 3.0 and 13.5) and the mean RNFL-thickness global was 65.9 µm (SD ± 16.1). Median MPOD measured at 0.51°, 1.02° and 1.99° retinal eccentricity in the glaucoma group was 0.42 DU, 0.34 DU and 0.13 DU, in the control group 0.40 DU, 0.35 DU and 0.12 DU respectively. There was no statistically significant difference of median MPOD between glaucomatous and control eyes (p=0.510, 0.735, 0.481). No significant relation between MPOD at 1.02 retinal eccentricity and the presence of glare symptoms was found (p=0.948). However, age seems to correlate with median MPOD measured at 1.02 retinal eccentricity (p=0.017).

Conclusion

There was no evidence for lower MPOD levels in our glaucoma patients; lower MPOD was not related to the presence of glare symptoms. However there seems to be a positive correlation between age and MPOD at 1.02° retinal eccentricity. To further investigate the relation between glare reported by glaucoma patients and glare disability linked to lower MPOD levels, additional studies are necessary that include both detailed inquiry of the quality of glare and a glare quantification and precise analysis of MPOD levels in glaucoma patients.

Correlation between Macular Pigment Optical Density and Neural Thickness and Volume of the Retina

Macular pigment (MP), which is composed of lutein/zeaxanthin/mezo-zeaxanthin, is concentrated in the central part of the retina, the macula. It protects the macula by absorbing short-wavelength light and suppressing oxidative stress. To evaluate whether MP levels are related to retinal neural protection and resulting health, we analyzed the association between the MP optical density (MPOD), and the macular thickness and volumes. Forty-three eyes of 43 healthy adult volunteers (21 men and 22 women; age: 22–48 (average 31.4 ± 1.1) years) were analyzed. Highly myopic eyes (<-6 diopters) were excluded. MPOD was measured using MPS2®, and the neural retinal thickness and volume were measured using optical coherence tomography. The mean MPOD was 0.589 ± 0.024, and it positively correlated with the central retinal thickness (P = 0.017, R = 0.360) and retinal volume of the fovea (1-mm diameter around the fovea; P = 0.029, R = 0.332), parafovea (1–3-mm diameter; P = 0.002, R = 0.458), and macula (6-mm diameter; P = 0.003, R = 0.447). In the macular area (diameter: 6 mm), MPOD was correlated with the retinal neural volume of the ganglion cell layer (P = 0.037, R = 0.320), inner plexiform layer (P = 0.029, R = 0.333), and outer nuclear layer (P = 0.020, R = 0.353). Thus, MPOD may help in estimating neural health. Further studies should determine the impact of MP levels on neuroprotection.

Spatial distribution of macular pigment estimated by autofluorescence imaging in elderly Japanese individuals

PURPOSE

To determine the spatial distribution types of macular pigment (MP) in elderly Japanese individuals and to consider their origin.

STUDY DESIGN

Observational case series.

METHODS

Local MP optical density (MPOD) at some eccentricities and MP volume were measured using the MPOD module of a MultiColor Spectralis in 96 pseudophakic eyes of 96 participants (age range, 52-86 years; mean age, 72.8 ± 8.3 years). The MP distribution types were determined from the MP spatial profiles. The retinal thickness (RT) at the foveal center, at both 0.5° and 0.9° eccentricities, and the foveal width were measured using optical coherence tomography.

RESULTS

The mean local MPOD at the foveal center was 0.79. Spatial distribution was classified into four types: central peak (24.0%), ring-like (40.6%), intermediate (22.9%), and central dip (12.5%). The ring-like type was the most frequent in these Japanese participants. The central-peak type showed lower MPOD than did the other types in the area outside 0.9°. The ring-like type occurred frequently in eyes with small RT at 0.5° and wider foveal width. A rough contour of the Müller cell cone was found more frequently in the central-dip type than in the other types.

CONCLUSIONS

The present characteristics of the different distribution patterns could be explained by the hypothesis that MP presents mainly in the Müller cell cone within 0.5° and in Müller cells in the outer and inner plexiform layers in the area outside 0.5°. The anatomic characteristics of Müller cells at the fovea and parafovea likely affect the MP distribution.

Reliability of colour perimetry to assess macular pigment optical density in age-related macular degeneration

Background:

The aim of this study was to determine the intra-session repeatability and inter-examiner reproducibility of the colour perimetry technique when assessing in vivo macular pigment optical density in age-related macular degeneration patients.

Methods:

Age-related macular degeneration patients were classified into four groups: early age-related macular degeneration, intermediate age-related macular degeneration, atrophic age-related macular degeneration and neovascular age-related macular degeneration after undergoing fundus photography (TRC 50DX type IA) and spectral-domain optical coherence tomography analysis (Topcon 3D-2000). Central fixation was confirmed in all patients using the MP-1 microperimeter (Nidek, Padua, Italy). To analyse repeatability, one examiner obtained three consecutive macular pigment optical density measures with MonCV3 device (Metrovision, Perenchies, France). To study agreement between two observers, a second examiner performed another macular pigment optical density measurement in random order. Within-subject standard deviation, coefficient of variation, and intraclass correlation coefficient data were obtained.

Results:

Fifty two (32 females and 20 males) consecutive age-related macular degeneration patients having a mean age of 71.5 ± 8.2 years were recruited. Six had early age-related macular degeneration, 25 had intermediate age-related macular degeneration, 10 had atrophic age-related macular degeneration and 11 had neovascular age-related macular degeneration. For repeatability, coefficient of variation values ranged from 22.3% (neovascular age-related macular degeneration) to 41.0% (atrophic age-related macular degeneration) and intraclass correlation coefficient values from 0.52 (intermediate age-related macular degeneration) to 0.79 (neovascular age-related macular degeneration). For agreement between two examiners, coefficient of variation values ranged from 20.1% (intermediate age-related macular degeneration) to 37.8% (neovascular age-related macular degeneration) and intraclass correlation coefficient values from 0.61 (neovascular age-related macular degeneration) to 0.80 (atrophic age-related macular degeneration).

Conclusion:

The reliability (intra-session repeatability and inter-examiner reproducibility) of colour perimetry technique to assess macular pigment optical density in age-related macular degeneration patients is only moderate. Thus, it cannot be recommended to be performed when evaluating and monitoring age-related macular degeneration patients in the daily clinic.

Rod-Mediated Dark Adaptation and Macular Pigment Optical Density in Older Adults with Normal Maculas

PURPOSE

To examine the association between macular pigment optical density (MPOD) and rod-mediated dark adaptation (RMDA) in persons ≥60 years old with normal maculas as determined by an accepted color fundus photography grading system.

METHODS

This cross-sectional analysis used baseline data from eyes in the Alabama Study on Early Age-Related Macular Degeneration. Eyes at step 1 in the AREDS 9-step grading system were considered normal. Eyes were additionally assessed by spectral domain optical coherence tomography (SD-OCT). Foveal MPOD was estimated via heterochromatic flicker photometry, and RMDA was assessed with a computerized dark adaptometer. The association between RMDA and MPOD was examined via Spearman correlation coefficients adjusted for age.

RESULTS

In 306 eyes from 306 persons (mean age 68.2 years) in normal macular health, MPOD was not associated with RMDA (age-adjusted rank correlation = 0.043, p = 0.45). After 81 eyes with incidental macular findings by SD-OCT evaluation were excluded, the association between MPOD and RMDA remained null (N = 225, age-adjusted r = 0.015, p = 0.82).

CONCLUSION

In a large sample of normal aged eyes, RMDA, a visual function that is rate limited by retinoid availability to photoreceptors across the complex of retinal pigment epithelium, Bruch's membrane, and choriocapillaris, is not related to MPOD in the neurosensory retina.

Dosage-dependent reduction of macular pigment optical density in female breast cancer patients receiving tamoxifen adjuvant therapy

It is now increasingly common for breast cancer patients to receive adjuvant tamoxifen therapy for a period of up to 10 years. As survival rate increases, managing tamoxifen ocular toxicities is important for patients' quality of life. Macular pigments in photoreceptor cells protect against free radical damage, which can cause macular degeneration. By reducing macular pigment concentration, tamoxifen may increase the risk of macular degeneration. Here, we compared macular pigment optical density (MPOD) and central macular thickness between breast cancer patients on tamoxifen adjuvant therapy (n = 70), and a control group (n = 72). Multiple regression analysis indicated that MPOD decreases with increasing tamoxifen dosage, up to a threshold of about 20 g, after which MPOD plateaus out. Mean MPOD in the treatment group (mean = 0.40) was significantly lower (p-value = 0.02) compared to the control group (mean = 0.47) for the left eye, and for the right eye (treatment mean = 0.39; control mean = 0.48; p-value = 0.009). No significant difference in mean central macular thickness was found between the treatment and the control group (p-values > 0.4). In the control group, MPOD and central macular thickness showed significant correlation (r∼0.30; p-values < 0.01) for both eyes. However, in the treatment group, loss of significant correlation was observed in the left eye (r = 0.21; p-value = 0.08). The present results show that MPOD decreases non-linearly as a function of tamoxifen dosage, and highlight the potential of tamoxifen to reduce macular pigment concentration through an unknown mechanism that does not depend on macular thinning solely.

The Association between Foveal Morphology and Macular Pigment Spatial Distribution: An Ethnicity Study

Purpose

Macular pigment (MP) spatial distribution varies considerably among individuals. We investigated ethnic variations in MP spatial distribution in relation to foveal architecture.

Methods

We measured MP optical density (MPOD) using heterochromatic flicker photometry (MAP test, City, University of London) in 76 white, 80 South Asian and 70 black volunteers (18 to 39 years). MPOD spatial profiles were classified objectively as exponential, ring-like or central dip, based on deviations away from an exponential fit. Measurements including total retinal thickness (RT), inner retinal layer (IRL), inner and outer plexiform layer (IPL and OPL) thickness, foveal width and foveal pit slope were taken from Spectralis SD-OCT (Heidelberg, Germany) scans.

Results

Integrated MPOD up to 1.8° (MPODint) was higher in South Asian (0.84±0.26) and black (0.84±0.31) than whites (0.63±0.24, P<0.0005). Ethnicity explained around 10% of the variance while gender played no significant role. MPOD profile phenotypes were associated with ethnicity: 58% with ring profiles were South Asian and 43% with dip profiles were black (χ²(4,226) = 13.4, P = 0.009). MPODint was lower in exponential (0.66±0.21) compared to ring-like (0.96±0.26) and central dip (1.00±0.32, P<0.0005) groups. White subjects had thicker IRL at 0° (130±21μm) than South Asian (123±16μm) and blacks (116±14μm; F(2) = 12.4, P<0.0005), with comparable results for IPL (P<0.0005) and OPL (P = 0.03). There was no significant difference in IRL, IPL or OPL (from 0 to 3.8° retinal eccentricity) or foveal width between MP profile groups (P>0.05).

Conclusion

We report a significant difference in the amount and distribution of MP between ethnicities that is not explained by variations in foveal morphology.

Association of macular pigment optical density with early stage of non-proliferative diabetic retinopathy in Chinese patients with type 2 diabetes mellitus

AIM

To detect the association between macular pigment optical density (MPOD), which reflects the antioxidant ability of retina, and diabetic retinopathy (DR) and to investigate the correlated factors of MPOD.

METHODS

Totally 435 subjects of urban Chinese were recruited to the study and divided into 3 groups: non-diabetes mellitus controls (NDM), diabetic patients without retinopathy (DWR), and patients with early stage of non-proliferative diabetic retinopathy (DR). Demographic and lifestyle characteristics were ascertained by questionnaire. A food-frequency questionnaire, general physical and ophthalmic examinations were completed for all participants. MPOD was measured by heterochromatic flicker photometry. Foveal thickness was measured by optical coherence tomography. The difference of MPOD among 3 groups was analyzed by analysis of covariance. The correlation analyses of MPOD with the candidate influence factors were assessed using the generalized estimating equations (GEE) model.

RESULTS

Of the 435 participants, 34 could not perform the MPOD measurements. Final analysis included 401 subjects, including 48 were in DR group, 134 in DWR group, and 219 in NDM group. MPOD was not significantly different among DR (0.49±0.21), DWR (0.45±0.21), and NDM (0.49±0.17) groups (P=0.24) after adjustment for fasting plasma glycemia, central foveal thickness, green vegetables, Chinese wolfberry, carotene and vitamin E. For all the 401 participants included, MPOD was positively associated with central foveal thickness (E=0.0007, P=0.001), Chinese wolfberry (E=0.0345, P=0.01), and green vegetables (E=0.0596, P<0.001) intake.

CONCLUSION

The data suggest that MPOD level is not statistically significantly influenced by the onset of diabetes or early stage of DR in the studied population. MPOD level is positively associated with thicker central foveal thickness and higher intake of foods containing carotenoids.

Optical Coherence Tomography Parameters in Morbidly Obese Patients Who Underwent Laparoscopic Sleeve Gastrectomy

Purpose. To investigate changes in optical coherence tomography parameters in morbidly obese patients who had undergone laparoscopic sleeve gastrectomy (LSG). Methods. A total of 41 eyes of 41 morbidly obese patients (BMI ≥ 40) who had undergone LSG were included in study. The topographic optic disc parameters, central macular thickness (CMT), total macular volume (TMV), and retinal ganglion cell layer (RGCL) were measured by spectral-domain optical coherence tomography (SD-OCT). Subfoveal choroidal thickness (SFCT) was measured by enhanced deep imaging-optical coherence tomography (EDI-OCT). Results. The mean CMT was 237.4 ± 24.5 μm, 239.3 ± 24.1 μm, and 240.4 ± 24.5 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean TMV was 9.88 ± 0.52 mm³, 9.96 ± 0.56 mm³, and 9.99 ± 0.56 mm³ preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean RGCL was 81.2 ± 6.5 μm, 82.7 ± 6.6 μm, and 82.9 ± 6.5 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). The mean SFCT was 309.8 ± 71.8 μm, 331.0 ± 81.4 μm, and 352.7 ± 81.4 μm preoperatively, 3 months postoperatively, and 6 months postoperatively, respectively (p < 0.01). No statistically significant differences were found between the preoperative values and 3- and 6-month postoperative values in rim area (p = 0.34), disc area (p = 0.64), vertical cup/disc ratio (p = 0.39), cup volume (p = 0.08), or retinal nerve fiber layer (p = 0.90). Conclusions. Morbidly obese patients who undergo LSG experience a statistically significant increase in CMT, TMV, SFCT, and RGCL at 3 months and 6 months after surgery.

Repeatability of Foveal Measurements Using Spectralis Optical Coherence Tomography Segmentation Software

Purpose

To investigate repeatability and reproducibility of thickness of eight individual retinal layers at axial and lateral foveal locations, as well as foveal width, measured from Spectralis spectral domain optical coherence tomography (SD-OCT) scans using newly available retinal layer segmentation software.

Methods

High-resolution SD-OCT scans were acquired for 40 eyes of 40 young healthy volunteers. Two scans were obtained in a single visit for each participant. Using new Spectralis segmentation software, two investigators independently obtained thickness of each of eight individual retinal layers at 0°, 2° and 5° eccentricities nasal and temporal to foveal centre, as well as foveal width measurements. Bland-Altman Coefficient of Repeatability (CoR) was calculated for inter-investigator and inter-scan agreement of all retinal measurements. Spearman's ρ indicated correlation of manually located central retinal thickness (RT₀) with automated minimum foveal thickness (MFT) measurements. In addition, we investigated nasal-temporal symmetry of individual retinal layer thickness within the foveal pit.

Results

Inter-scan CoR values ranged from 3.1μm for axial retinal nerve fibre layer thickness to 15.0μm for the ganglion cell layer at 5° eccentricity. Mean foveal width was 2550μm ± 322μm with a CoR of 13μm for inter-investigator and 40μm for inter-scan agreement. Correlation of RT₀ and MFT was very good (ρ = 0.97, P < 0.0005). There were no significant differences in thickness of any individual retinal layers at 2° nasal compared to temporal to fovea (P > 0.05); however this symmetry could not be found at 5° eccentricity.

Conclusions

We demonstrate excellent repeatability and reproducibility of each of eight individual retinal layer thickness measurements within the fovea as well as foveal width using Spectralis SD-OCT segmentation software in a young, healthy cohort. Thickness of all individual retinal layers were symmetrical at 2°, but not at 5° eccentricity away from the fovea.

The use of heterochromatic flicker photometry to determine macular pigment optical density in a healthy Australian population

PURPOSE

To establish the normal macular pigment density (MPOD) in a healthy adult Australian sample using heterochromatic flicker photometry (HFP).

METHODS

Macular pigment density was measured using heterochromatic flicker photometry in a total of 201 subjects ranging in age from 21 to 84 years with healthy macula. Fifty-seven of the healthy subjects also completed a food-frequency dietary questionnaire. Best-corrected visual acuity (BCVA) was measured using logMAR, chart and macular morphological profiles were assessed using high-resolution integrated Fourier-domain optical coherence tomography (OCT).

RESULTS

The average MPOD value was 0.41 ± 0.20 (range 0.07-0.79). There was no statistically significant difference between values in the left and right eye, with good interocular agreement (0.41 vs 0.40, r = 0.893, p < 0.01). Age significantly predicted MPOD score (R (2) = 0.07, p < 0.05). A subgroup analysis of patients who completed the dietary questionnaire revealed a close correlation between higher diet scores and higher MPOD (r = 0.720 p = 0.031). There was no effect of smoking, gender, or iris colour on MPOD values. There was no significant correlation between BCVA, macular OCT profiles, and MPOD.

CONCLUSION

Given that MPOD values are potentially affected by geographical variation, we have determined a mean MPOD value for healthy subjects in a population south of the equator, providing a reference point for future studies on Caucasian samples.

Foveal slope measurements in subjects with high-risk of age-related macular degeneration

Background:

Recent reports indicated that the slope of the foveal depression influences the macular pigment (MP) spatial profile. MP has been shown to confer possible protection against age-related macular degeneration (ARMD) because of its antioxidant properties.

Aims:

To study the configuration of foveal slope and the foveal thickness in fellow eyes of subjects with unilateral neovascular ARMD.

Settings and design:

Case-control series.

Materials and Methods:

The study population consisted of 30 cases aged >50, who had unilateral choroidal neovascular membrane (CNVM) or disciform scar in the fellow eye and 29 controls aged >50, who had no sign of ARMD in the either eye. Using spectral-domain optical coherence tomography, foveal thickness at different locations including the central subfield foveal thickness (CSFT) was noted. The foveal slopes were calculated in the six radial scans (between 0.25° and 1° retinal eccentricity) as well as the 3D scan.

Results:

Cases had a significantly higher CSFT when compared to controls (215.1 ± 36.19 μ vs. 193.0 ± 17.38 μ, P = 0.004). On the 3D scan, the cases had shallower superior (cases 1.32 ± 0.32 vs. controls 1.45 ± 0.13, P = 0.04) and temporal slopes (cases 1.27 ± 0.21 vs. controls 1.39 ± 0.12, P = 0.01) in comparison to the controls.

Conclusions:

We noted a shallower superior and temporal foveal slope and a higher CSFT in the fellow eyes of subjects with a unilateral neovascular ARMD. Prospective studies observing the development of CNVM in subjects with altered foveal slope might provide more information on this optical coherence tomography finding.

Inverse relationship between macular pigment optical density and axial length in Chinese subjects with myopia

BACKGROUND

Macular pigment (MP) has been the focus of much attention in recent years, due to its protective effect against macular degenerations. In this study, we investigated the association between macular pigment optical density (MPOD) and axial length (AL) in Chinese subjects with myopia.

METHODS

In total, 173 myopes (mean spherical equivalent [MSE] ≤-1.00D) were recruited for this prospective observational study. MPOD was measured in both eyes of each subject using a macular metrics densitometer. AL was measured in eyes using an IOL-Master. A raw coefficient of correlation analysis and a partial correlation analysis were used to investigate the relationship between MPOD and AL.

RESULTS

The age of the subjects ranged from 18 to 67 years. The overall mean MPOD for the cohort was 0.412 ± 0.119 (range, 0.105-0.812). The mean AL was 25.18 ± 1.08 mm (range, 23.14-28.19 mm). Using a raw coefficient of correlation, a significant inverse correlation was found between MPOD and AL (r= -0.134, p=0.012). When using a partial correlation analysis to eliminate the impact of covariant, a significant inverse correlation was also found between MPOD and AL (r= -0.142, p=0.008). Furthermore, when AL was divided into two groups: AL>26 mm and AL ≤ 26 mm, a significant inverse correlation was observed between MPOD and AL in the former (r= -0.253, p=0.029), but no significant relationship was observed between these in the latter (r=0.104, p=0.067).

CONCLUSIONS

MPOD correlated inversely with AL in this sample of Chinese subjects with myopia.

Macular pigment optical density and its relationship with refractive status and foveal thickness in Chinese school-aged children

PURPOSE

To investigate macular pigment optical density (MPOD) and its relationship with refractive status and foveal thickness in Chinese school-aged children.

METHODS

Ninety-four healthy Chinese children, 6 to 12 years old, were recruited to the study. MPOD was measured with a heterochromatic flicker photometer (HFP), and foveal thickness, including both minimum and central foveal thicknesses (MFT and CFT, respectively), were measured by optical coherence tomography (OCT) with fast macular map scan. A noncontact tonometer was used to measure intraocular pressure (IOP) followed by determination of the refraction using an autorefractor after cycloplegia. Information on body mass index (BMI) was obtained. The correlation between MPOD values and foveal thickness, spherical equivalent (SE) refraction, IOP, BMI, sex, and age was statistically analyzed using SAS 8.2 statistical software.

RESULTS

The MPOD in examined school-aged children was 0.56 ± 0.25, without any significant difference between boys and girls (p = 0.12). MPOD showed no significant association with age, BMI, IOP, SE, MFT, or CFT. In the myopia group, however, there was an inverse relationship between MPOD and MFT (R =-0.66, p = 0.028) and a positive relationship between MPOD and CFT (R = 0.67, p = 0.025).

CONCLUSIONS

MPOD was inversely related to MFT and positively related to CFT in Chinese school-age children with low-to-moderate myopia. MPOD showed no significant association with age, BMI, IOP, SE or foveal thickness.

Correspondence between retinal reflectometry and a flicker-based technique in the measurement of macular pigment spatial profiles

A comparison of macular pigment optical density (MPOD) spatial profiles determined by an optical and a psychophysical technique is presented. We measured the right eyes of 19 healthy individuals, using fundus reflectometry at 0, 1, 2, 4, 6, and 8 deg eccentricity; and heterochromatic flicker photometry (HFP) at 0, 0.5, 1, 2, 3, 4, 5, 6, and 7 deg, and a reference point at 8 deg eccentricity. We found a strong correlation between the two techniques. However, the absolute estimates obtained by fundus reflectometry data were higher than by HFP. These differences could partly be explained by the fact that at 8 deg eccentricity the MPOD is not zero, as assumed in HFP. Furthermore, when performing HFP for eccentricities of <1 deg, we had to assume that subjects set flicker thresholds at 0.4 deg horizontal translation when using a 1-deg stimulus. MPOD profiles are very similar for both techniques if, on average, 0.05 DU is added to the HFP data at all eccentricities. An additional correction factor, dependent on the steepness of the MPOD spatial distribution, is required for 0 deg.