MyVisionTest News Archive
Jul 19, 2010
Macular pigment assessment in clinical practice
Commercially available devices for measuring macular pigment are not precise enough to detect the increase in pigment that normally occurs following lutein supplementation, according to a new study.
Twenty-four studies have investigated the repeatability of macular pigment optical density (MPOD) measurements using heterochromatic flicker photometry. Of these, 10 studies provided a coefficient of repeatability or data from which the coefficient could be calculated, with a range in values of 0.06 to 0.58. The lowest coefficient of repeatability assessed on naïve subjects alone was 0.08.
The coefficient of repeatability is twice the standard deviation of the differences between the two measurements. In other words, there is a 95% chance that a second reading on the same patient using the same instrument will vary by more or less than that amount purely by chance. Only changes greater than the coefficient of repeatability can be assured of being due to actual changes in the patient and not an artifact of instrument variability.
These values tell us that, at best, changes greater than 0.08 can be considered clinically significant and at worst, only changes greater than 0.58 can be considered clinically significant.
Six studies assessed the effect of supplementation with up to 20 mg/day lutein on macular pigment optical density measured using heterochromatic flicker photometry and the mean increase in macular pigment optical density ranged from 0.025 to 0.09.
It seems reasonable to conclude that the chance of eliciting an increase in macular pigment optical density during six months of daily supplementation with between 10 and 20 mg lutein that is of sufficient magnitude to be detected by using heterochromatic flicker photometry on an individual basis is small.
The investigators conclude that commercially available heterochromatic flicker photometers for macular pigment optical density assessment in the clinical environment appear to demonstrate particularly poor coefficient of repeatability values. They advise caution when considering the use of these instruments for monitoring of macular pigment optical density in response to supplementation in individual patients.
WHAT IT MEANS TO YOU: Lutein supplementation will often result in an increase in macular pigment. Increases in macular pigment can improve vision, filter out harmful rays of the sun, and provide antioxidant protection. There are a variety of different ways to measure macular pigment, but all of the devices in this study use heterochromatic flicker photometry, a subjective method that relies upon the patient to make adjustments to the instrument until an endpoint is reached. To some degree, the precision and repeatability of these devices are limited by the observation skills of the patient. Given the limitations of these devices, as highlighted by the current study, there seems to be little value in using them to monitor patients on lutein supplementation.
Read more...
Clin Exp Optom. 2010 Jul 14. [Epub ahead of print]
Tags: lutein, macular pigment
Commercially available devices for measuring macular pigment are not precise enough to detect the increase in pigment that normally occurs following lutein supplementation, according to a new study.Twenty-four studies have investigated the repeatability of macular pigment optical density (MPOD) measurements using heterochromatic flicker photometry. Of these, 10 studies provided a coefficient of repeatability or data from which the coefficient could be calculated, with a range in values of 0.06 to 0.58. The lowest coefficient of repeatability assessed on naïve subjects alone was 0.08.
These values tell us that, at best, changes greater than 0.08 can be considered clinically significant and at worst, only changes greater than 0.58 can be considered clinically significant.
Six studies assessed the effect of supplementation with up to 20 mg/day lutein on macular pigment optical density measured using heterochromatic flicker photometry and the mean increase in macular pigment optical density ranged from 0.025 to 0.09.
It seems reasonable to conclude that the chance of eliciting an increase in macular pigment optical density during six months of daily supplementation with between 10 and 20 mg lutein that is of sufficient magnitude to be detected by using heterochromatic flicker photometry on an individual basis is small.
The investigators conclude that commercially available heterochromatic flicker photometers for macular pigment optical density assessment in the clinical environment appear to demonstrate particularly poor coefficient of repeatability values. They advise caution when considering the use of these instruments for monitoring of macular pigment optical density in response to supplementation in individual patients.
WHAT IT MEANS TO YOU: Lutein supplementation will often result in an increase in macular pigment. Increases in macular pigment can improve vision, filter out harmful rays of the sun, and provide antioxidant protection. There are a variety of different ways to measure macular pigment, but all of the devices in this study use heterochromatic flicker photometry, a subjective method that relies upon the patient to make adjustments to the instrument until an endpoint is reached. To some degree, the precision and repeatability of these devices are limited by the observation skills of the patient. Given the limitations of these devices, as highlighted by the current study, there seems to be little value in using them to monitor patients on lutein supplementation.
Read more...
Clin Exp Optom. 2010 Jul 14. [Epub ahead of print]
