Authors' response:clinical evaluation of the MPS 9000 macular pigment screener

As a research group with no commercial interest in any macular pigment optical density (MPOD) measurement devices or nutritional supplements, we feel that we were well-placed to carry out an independent clinical assessment of the reliability of the MPS 9000 (Tinsley Precision Instruments, Redhill, Surrey, UK). Our study was prompted by the fact that we could not find any reported coefficient of repeatability value within the literature, and none was provided by the manufacturer.1 We had planned to use this instrument in our own research studies investigating the impact of nutritional supplementation on MPOD. For this purpose, we needed …