An evaluation of a novel instrument for measuring macular pigment optical density: the MPS 9000

Abstract

. Purpose: Of the antioxidants found in the human retina, only the macular carotenoid quantities can be estimated noninvasively (albeit in a collective fashion), thus facilitating study of their role in that tissue. The aim of this study was to evaluate concordance between macular pigment optical density (MPOD) values recorded on a commercially available instrument, the MPS 9000, with those of an already validated heterochromatic flicker photometry instrument. Also, we assessed and compared test–retest variability for each instrument. Methods: Macular pigment optical density at 0.5 retinal eccentricity was measured using two different heterochromatic flicker photometers, the MPS 9000 and the Macular DensitometerTM, in 39 healthy subjects. Test–retest variability was evaluated separately for each instrument by taking three readings over a 1‐week period in 25 subjects. Results: There was a moderate positive correlation for MPOD at 0.5° of retinal eccentricity between the MPS 9000 and the Macular Densitometer described by the linear equation y = 0.763x + 0.172 (r = 0.68, p < 0.001, r2 = 0.46); however, a paired‐samples t‐test showed a significant difference in terms of mean values, with a bias of lower MPOD values being yielded by the MPS 9000 (t = −4.103, p < 0.001). Bland–Altman analysis indicated only moderate agreement between the two instruments, reflected in 95% limits of agreement of 0.1 ± 0.27. Inter‐sessional repeatability, expressed as a coefficient of repeatability, ranged from 0.18 to 0.21 [mean (±SD): 0.19 (0.02)] for the MPS 9000 and from 0.11 to 0.12 [mean (±SD): 0.12 (0.01)] for the Macular Densitometer. Conclusion: The results demonstrate that the MPS 9000 consistently yields MPOD readings, which are lower than that found with the Macular Densitometer, and exhibits substantial test–retest variability.

Macular pigment optical density: repeatability, intereye correlation, and effect of ocular dominance

“…The literature was not consistent with some studies finding the repeatability not acceptable,25,28 whereas some other finding the repeatability acceptable 26,29. All these studies25,28 have smaller sample sizes ranging from 23 to 40 individuals, whereas the present study had a relatively larger sample size. The possible explanation of the difference in results lies in the quantity and quality of data collected and understanding of the tests by the individuals.…”

Evidence of lower macular pigment optical density in chronic open angle glaucoma

“…The magnitude of the difference in MPOD between glaucoma cases and controls (MPOD 34% lower in glaucoma cases on average) is comparable to that observed for other conditions, where oxidative stress is a likely contributory factor, such as AMD, where magnitude differences up to 53% have been reported 18. The repeatability of the test–retest MPOD values is also similar to that observed elsewhere among normal observers using the HFP technique,19 and provides further assurance as to the validity of the MPOD differences observed.…”

Clinical imaging of macular pigment optical density and spatial distribution

“…The MPS 9000 has demonstrated a poor agreement with the MacuScope (−0.02 ± 0.44 density units) and significant individual variability between instruments . The MPS 9000 showed a significant agreement with the Macular Densitometer (r = 0.68, p < 0.001), although the MPS 9000 demonstrated consistently lower MPOD values and higher test‐retest variability . A separate study showed significant agreement between the Macular Densitometer and the Maculometer, although the Maculometer tended to underestimate MPOD in older subjects and subjects with high macular pigment values …”

“…68 The MPS 9000 showed a significant agreement with the Macular Densitometer (r = 0.68, p < 0.001), although the MPS 9000 demonstrated consistently lower MPOD values and higher test-retest variability. 69 A separate study showed significant agreement between the Macular Densitometer and the Maculometer, although the Maculometer tended to underestimate MPOD in older subjects and subjects with high macular pigment values. 70 A 2013 study used healthy adults to evaluate three commercially available instruments encompassing all three techniques: the Macular Densitometer using cHFP, the Heidelberg Spectralis HRA + OCT Multi-Color using fundus autofluorescence and the Visucam 200 using fundus reflectometry.…”