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Robert Donati, Elizabeth Wyles; A Comparison of the MacuScope and QuantifEye Macular Pigment Densitometers in Two Distinct Population Types. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3777.
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Studies have suggested that reduced levels of macular pigment (MP) may increase risk for developing age-related macular degeneration (AMD). There are two compact commercially available heterochromic flicker photometry instruments that measure MP in the USA. Previous studies revealed significant variability between instruments. Our aim was to determine if the same variability would be found in a young, healthy, population compared to an older population for which these instruments have more significance.
Twenty young healthy adults (21-29 years old) and 28 older adults (50-70 years old) with and without early signs of AMD were recruited from the Illinois Eye Institute patient base. Macular pigment optical density (MPOD) was measured using the MacuScope and QuantifEye. Data was collected for each patient in one session. A single, but different operator collected data for each of the patient populations. Two measurements per eye were taken on each instrument and each eye was used as a separate data point. If the difference was greater than 0.04 absorbance units between two measurements on a single instrument, a third measurement was taken. Invalid readings were excluded. Paired t-tests and ANOVA were done to compare the statistical significance of the results from both instruments and age groups. Bland-Altman plots were done for an added comparison.
Mean MPOD for the combined age groups was 0.335 ± 0.137 for the MacuScope (n=83) and 0.350 ± 0.186 for the QuantifEye (n=83). There was no significant difference between the MPOD means. The mean standard deviation of each subject’s MPOD readings was 0.0943 ± 0.0822 for the MacuScope (n=87) and 0.0508 ± 0.0496 for the QuantifEye (n=86). There is a significant difference between the two instruments (p<0.0005) when considering individual subject variability.
If MPOD is monitored with the possibility of altering treatment, the need for reliable measurements is imperative. From this limited study, both instruments appear to demonstrate reliability based on the mean MPOD readings and differences between those means. However, when critically looking at each subject’s data points, there is significant variability between the instruments. Thus, the clinician must take this into account if using MPOD as an indicator for AMD risk and/or clinical care.
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