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

Retinal Changes From Hyperopia to Myopia: Not All Diopters Are Created Equal

Purpose

To quantitatively characterize retinal changes across different quantiles of refractive error in 34,414 normal eyes of 23,064 healthy adults in the UK Biobank.

Methods

Twelve optic disc (OD), foveal and vascular parameters were derived from color fundus photographs, correcting for ocular magnification as appropriate. Quantile regression was used to test the independent associations between these parameters and spherical equivalent refraction (SER) across 34 refractive quantiles (high hyperopia to high myopia)-controlling for age, sex and corneal radius.

Results

More negative SER was nonlinearly associated with greater Euclidian (largely horizontal) OD-fovea distance, larger OD, less circular OD, more obliquely orientated OD (superior pole tilted towards the fovea), brighter fovea, lower vascular complexity, less tortuous vessels, more concave (straightened out towards the fovea) papillomacular arterial/venous arcade and wider central retinal arterioles/venules. In myopia, these parameters varied more strongly with SER as myopia increased. For example, while every standard deviation (SD) decrease in vascular complexity was associated with 0.63 D (right eye: 95% confidence interval [CI], 0.58-0.68) to 0.68 D (left eye: 95% CI, 0.63-0.73) higher myopia in the quantile corresponding to -0.60 D, it was associated with 1.61 D (right eye: 95% CI, 1.40-1.82) to 1.70 D (left eye: 95% CI, 1.56-1.84) higher myopia in the most myopic quantile. OD-fovea angle (degree of vertical separation between OD and fovea) was found to vary linearly with SER, but the magnitude was of little practical importance (less than 0.10 D variation per SD change in angle in almost all refractive quantiles) compared with the changes in OD-fovea distance.

Conclusions

Several interrelated retinal changes indicative of an increasing (nonconstant) rate of mechanical stretching are evident at the posterior pole as myopia increases. These changes also suggest that the posterior pole stretches predominantly in the temporal horizontal direction.

Macular pigment optical density responses to different levels of zeaxanthin in patients with high myopia

PURPOSE

Measurement of macular pigment optical density (MPOD) can be conducted to assist in the diagnosis of multiple fundus diseases.

METHODS

Fifty-four subjects with high myopia were prospectively recruited for a 3-month clinical trial. Detailed ophthalmologic examinations and MPOD measurements were performed. The subjects in each high myopia category group were randomly subdivided into 5 intervention groups, including a low-dose Lycium barbarum group (10 g Lycium barbarum, containing 10 mg of zeaxanthin and 1 mg of lutein), low-dose control group (1 mg of lutein), high-dose Lycium barbarum group (20 g of Lycium barbarum, containing 20 mg of zeaxanthin and 2 mg lutein), high-dose control group (2 mg of lutein), and a blank control group. Differences in the MPODs among the high myopia groups were calculated with Welch two-sample t tests. A linear mixed-effects model was constructed and Pearson's correlation analysis was performed to determine correlations between MPOD and other factors. The MPOD values at baseline and the 3-month follow-up were compared with the Mann-Whitney test.

RESULTS

The category 1 group had a significantly higher MPOD than the category 2 (P = 0.02) and category 3 groups (P < 0.001). The category 2 group had a significantly higher MPOD than the category 3 group (P < 0.001). The MPOD significantly decreased with increasing axial length (AL) and decreasing best-corrected visual acuity (BCVA) in the category 1-3 groups and with increasing age and increasing intraocular pressure (IOP) in the category 2-3 groups. The MPOD was significantly higher in the group who received high-dose zeaxanthin from Lycium barbarum than in the group who received high-dose lutein at 3 months (P = 0.0403), while no significant difference was identified between the low-dose zeaxanthin group and low-dose lutein group (P = 0.1117).

CONCLUSIONS

The MPOD was negatively correlated with the category of high myopia. Supplementation of zeaxanthin from Lycium barbarum is beneficial in preventing the loss of macular pigment of high myopia patients.

TRIAL REGISTRATION

Trial registration number and date of registration: ChiCTR2100046748.

Association of hsa-mir-328-3p Expression in Whole Blood With Optical Density of Retinal Pigment Epithelial Cells

AIM

To investigate the association of the pair box 6 gene (PAX6) and hsa-miR-328-3p with optical density of macular pigment.

MATERIALS AND METHODS

We evaluated 112 individuals (34 with moderate myopia, eight with high-degree myopia, and 70 healthy individuals). The optical density of macular pigment was measured using single-wavelength reflectometry. DNA and RNA were extracted from whole blood samples. Expression of hsa-miR-328-3p and genotyping of single-nucleotide polymorphism of PAX6 (rs662702) were performed using Applied Biosystems 7900HT real-time polymerase chain reaction system. Optical density of retinal pigment epithelial cells was evaluated using Fundus plus camera.

RESULTS

In the group with myopia, with increasing ∆Ct hsa-miR-328-3p, the median optical density of the retinal pigment epithelium decreased statistically significantly (p<0.032). No statistically significant association was found between SNP rs662702 genotype variant of the PAX6 gene and the optical density of the retinal pigment epithelium.

CONCLUSION

The increased expression of hsa-miR-328-3p in the blood indicates a decrease in the optical density of the retinal pigment epithelium in those with myopia.

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.

Macular pigment optical density in a Brazilian sample

Background

To evaluate macular pigment optical density (MPOD) and to identify its determinants in a sample of Brazilian individuals.

Methods

This was a cross-sectional study. One hundred three healthy individuals had both eyes photographed using a Visucam 500 digital fundus camera (Carl Zeiss Meditec, Jena, Germany) in combination with the MPOD module. Four variables were obtained: maximum MPOD, mean MPOD, MPOD volume, and MPOD area. Demographic data and information on lifestyle habits were also collected.

Results

Mean MPOD was 0.14 density unit ± 0.05. MPOD was not influenced by gender, smoking history, or refractive error. MPOD was significantly higher among black individuals than among white and biracial individuals. There was a positive but low correlation between MPOD and age.

Conclusion

This study found MPOD values to be similar to those found in European samples but lower than other studies performed on Asian and Australian samples. This is the first data regarding MPOD in a South American Population.

Comparison of macular pigment and serum lutein concentration changes between free lutein and lutein esters supplements in Japanese subjects

PURPOSE

To compare changes in macular pigment optical density (MPOD) and serum lutein concentration between free lutein and lutein esters supplements in healthy Japanese individuals.

METHODS

Twenty healthy subjects (age range, 22-47 years) were recruited into this prospective, randomized, doubled-blind comparative study. Individuals were evenly divided into two groups: free lutein group, supplementation with 10 mg of free lutein; or lutein esters group, supplementation with 20 mg of lutein esters equivalent to 10 mg of free lutein. Each participant took either type of oral lutein daily for 3 months. The serum lutein concentrations and MPOD levels were measured at baseline and 3 and 6 months after the start of supplementation.

RESULTS

There were no significant differences in the serum lutein concentrations and MPOD levels at baseline between the groups. The increased serum lutein concentration and MPOD levels at 3 months were respectively, 89% and 38% in the free lutein group and 97% and 17% in the lutein esters group. The serum lutein concentrations in both groups and MPOD levels in the free lutein group increased significantly (p < 0.05) from baseline. No significant differences in serum lutein concentrations and MPOD levels were seen between the groups. Three months after supplementation ended, the serum lutein concentration decreased; the MPOD remained elevated in both groups.

CONCLUSIONS

The serum lutein concentrations and MPOD levels increased significantly with either free lutein or lutein esters, and no significant differences were found between the two. Both were considered useful as lutein supplements.