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Juan Carlos Sanabria, Jordan Spencer Bass, Frank Spors, Dennis L Gierhart, Pinakin Gunvant Davey; Macular Pigment Reflectometry: A Technique To Measure Peripheral Measurements. Invest. Ophthalmol. Vis. Sci. 2019;60(9):38.
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© ARVO (1962-2015); The Authors (2016-present)
The Macular Pigment Reflectometer (MPR; ZeaVision St-Louis MO, USA), an objective and commercial prototype, employs a quartz halogen source to project a controlled light spectrum onto the retina (Figure 1). Given that the absorption and reflectance functions of various chromophores and structures in human eye are known, the analysis of reflected light received by the instrument spectrometer allows for quantitative isolation and measurement of lutein and zeaxanthin optical densities (L-OD, Z-OD) along with overall macular pigment optical density (MPOD) from the overall retinal reflectivity signal. Prior work has shown that the measurements objectively obtained from the MPR is repeatable and reliable. In this study we report a technique to measure MPOD, L-OD and Z-OD in the periphery and report data at central and one- and two-degree off-center measurements.
The study was conducted at one clinical site; the Eye Care Institute, Western University of Health Sciences, College of Optometry, Pomona, CA USA. All study measurements were completed in a single session, with one eye undergoing measurements by a trained observer, and a second trained observer adjusting the peripheral track system (see figure 2). Eight eyes of eight individuals were examined for the purpose of this study. The mean age of the study participants was 26.33 years (SD 2.35 years). An adjustable track system with red LED lights 20 feet away from the patient was created with each light being spaced one degree from each other to test for each eccentricity. The L-OD and Z-OD measurements were performed using the MPR device twice post-dilation.
The mean MPR-MPOD value for the dilated central measurement was 0.579 (SD 0.128) with L-OD to Z-OD ratio of 1:2.52. In contrast, the MPR-MPOD value for the dilated peripheral measurement at one degree was 0.295 (SD 0.132) and the mean MPR-MPOD value for the dilated peripheral measurement at two degrees was 0.158 (SD 0.09). The L-OD to Z-OD ratio at one-degree and two degree off center was 1:0.832 (SD 1.2) and 1:0.465 (SD 0.919) respectively.
The results of our study indicate that MPOD measurements obtained using the MPR decreases as a function of eccentricity. There is a higher concentration of Zeaxanthin centrally compared to Lutein. This ratio changes in the periphery with twice as more lutein than zeaxanthin at about two-degree off-center.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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