Influence of macular oedema on the measurement of macular pigment optical density

Macular pigment optical density of hyperopic anisometropic amblyopic patients measured by fundus reflectometry

Purpose

Hyperopic anisometropia is a major cause of amblyopia and may be associated with macular pigment optical density (MPOD) reduction. To explore whether the MPOD changes in hyperopic anisometropic amblyopia, we measured the MPOD using fundus reflectometry in eyes with hyperopic anisometropic amblyopia and normal vision.

Methods

This was a cross-sectional study conducted from January 2017 to June 2017. Forty subjects (25 males and 15 females) between the ages of 6 and 10 years were recruited. The subjects' eyes were divided into two groups: amblyopic eyes (best-corrected visual acuity (BCVA) not more than 20/25 or BCVA of two eyes differing by two or more lines) and fellow eyes. All enrolled subjects underwent a comprehensive ophthalmic examination, including extraocular motility assessment, cover-uncover testing, and refractive error (noncycloplegic), BCVA, axial length (AL), macular foveal thickness (MFT) and MPOD (Visucam^® 200, Carl Zeiss Meditec AG, Germany).

Results

The MPOD of amblyopic and fellow eyes was 0.12 ± 0.03 log units and 0.13 ± 0.04 log units, respectively, with a significant difference (P = 0.026). The MFT of amblyopic and fellow eyes was 241.28 ± 13.95 and 237.13 ± 16.02 μm, respectively, revealing that the MFT was significantly higher in amblyopic eyes than in fellow eyes (P = 0.028). Conversely, there was no correlation between the MPOD and MFT in the two groups.

Conclusions

This study is the first to report that the MPOD is decreased in hyperopic anisometropic amblyopia. In this study, no correlation between the MPOD and MFT was found. In the future, factors that induce a decrease in the MPOD in eyes with hyperopic anisometropic amblyopia should be explored in a large-sample study with follow-up observation.

Macular Pigment Optical Density Measured by a Single Wavelength Reflection Photometry with and without Mydriasis

PURPOSE

1. To evaluate the repeatability of macular pigment optical density (MPOD) measurements in non-mydriatic and mydriatic conditions with a single wavelength reflection photometry. 2. To compare the non-mydriatic measurement with the mydriatic measurement of MPOD values.

METHODS

Fifty-one healthy young subjects were recruited in this prospective study. MPOD parameters including maximum optical intensity (OD), mean OD, volume and area, were measured using a single 460-nm wavelength reflection method (Visucam 200, Carl Zeiss Meditec) twice both before and after pupil dilation. Paired t test, Pearson's correlation, intraclass correlation coefficient (ICC) and Bland-Altman plots were used to evaluate the agreement and correlation of MPOD parameters before and after mydriasis.

RESULTS

The differences of maximum OD, mean OD and volume between the two measurements without mydriasis was statistically significant for all parameters, but not significant between the two measurements with mydriasis or between non-mydriatic and mydriatic measures. The ICCs were higher for the two measurements with mydriasis (range: 0.687-0.840) than those without mydriasis (range: 0.448-0.695) or non-mydriatic and mydriatic measures (range: 0.473-0.769). The 95% limit of agreement (LOA) of measurements between the two measurements after mydriasis was the smallest among all the other comparisons. The coefficient of repeatability was lower for the measurements with mydriasis than those without mydriasis.

CONCLUSIONS

MPOD measurement by Visucam 200 with mydriasis has higher repeatability than the measurement without mydriasis. The non-mydriatic and mydriatic measures had less agreement compared to the two measure after mydriasis. Therefore, mydriasis is recommended.