Abstract
Purpose :
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) from the overall retinal reflectivity signal. We evaluated the MPR unit’s ability to calculate L-OD and Z-OD with the intent to create protocols that can be utilized in clinics and subsequent studies.
Methods :
Thirty eyes of thirty individuals were examined for the purposes of the study. The mean age of the study participants was 30.73 years (SD 6.87 years) and visual acuity of 20/20 or better in the study eye. The measurements were performed using the MPR device twice undilated and twice post pupillary dilation. The participants fixate at a light source that illuminates 1-degree of the retina for 40 seconds. The light reflected from the retina is received and analyzed by a spectrometer. The machine in-built software calculates the L-OD and Z-OD. The correlation and the difference in the two measures obtained undilated conditions and under dilated conditions was calculated. The coefficient of repeatability was also assessed between first and second measures.
Results :
The detailed results of L-OD and Z-OD are provided in figure 2 and 3 below. Depending on which part of the 40 second duration was analyzed the mean L-OD was in the range of 0.20 to 0.31 and the Z-OD ranged from 0.49 to 0.54. There was a statistically significant difference in first and second undilated L-OD and Z-OD values (see figure 2 and 3). The results of L-OD and Z-OD appears to be most stable when obtained in dilated conditions and in the 10-30 second time interval of measurement. The ratio L-OD to Z-OD as measured by the MPR appears to be 1 to 2.3 which is consistent with prior reports (see Bernstein et al., Vision Research 2010).
Conclusions :
The MPR device can measure the L-OD and Z-OD non-invasively, in-vivo, in about 30 seconds and at this point in instrument development, pupillary dilation is necessary to obtain repeatable values of L-OD and Z-OD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.