Repeatability of the macular pigment spatial profile: A comparison of objective versus subjective classification.

Irene Ctori,Byki Huntjens,Omar A Mahroo,Christopher J Hammond,Katie M Williams

doi:10.1111/aos.13725

Irene Ctori, Byki Huntjens + Show 3 more

Open Access

https://doi.org/10.1111/aos.13725

Copy DOI

Abstract

PurposeClassification of macular pigment (MP) spatial profile phenotypes varies and is often based on subjective visualisation. We investigated repeatability of MP optical density (MPOD) comparing an objective versus subjective profiling system.MethodsThe coefficient of repeatability (CoR) was calculated for point MPOD values (0–3.8°) obtained by dual‐wavelength fundus autofluorescence (FAF) from two scans obtained in a single visit of 40 healthy individuals (39 ± 9 years). For each individual's dataset, the MP profile was classified as exponential, ring‐like or central dip using an objective method (based on deviations away from an exponential fit), as well as by subjective visual profiling. Existing FAF images of 88 monozygotic (MZ) and 69 dizygotic (DZ) twin pairs were reanalysed using the objective profiling method and concordance and heritability of ring‐like profiles determined.ResultsThe CoR was 0.23 at 0° and 0.06 at 0.8°. Agreement of objective profiling between scans was excellent (κ = 0.85, 95% CI 0.69 to 1.00; p < 0.0005). Subjective profiling showed moderate agreement between scans (κ = 0.48, 95% CI 0.23 to 0.73; p < 0.0005). Agreement between objective and subjective classification was low (κ = 0.23, 95% CI 0.04 to 0.42; p = 0.02). Concordance for the ring‐like profile using objective profiling was 0.74 for MZ compared to 0.36 for DZ twins. Heritability was calculated as 81.5% (95% confidence interval 61.1–93.1%).ConclusionCompared to visual assessment, objective MP profiling is a more reliable method and should be considered in future observational and interventional studies. In addition, MP profile phenotypes showed high heritability.

Highlights

Macular pigment (MP) is thought to serve a protective function shielding the central photoreceptors from the damaging effects of blue light (Junghans et al 2001; Barker et al 2011)
The repeatability of single macular pigment optical density (MPOD) measurements varies according to retinal eccentricity
Based on the twowavelength fundus autofluorescence (FAF) technique, MPOD fluctuations greater than 0.23 at 0°, 0.12 at 0.1° and 0.06 at 0.8° can be considered as clinically significant perturbations in the data as opposed to instrument noise

Summary

Introduction

Macular pigment (MP) is thought to serve a protective function shielding the central photoreceptors from the damaging effects of blue light (Junghans et al 2001; Barker et al 2011). The area under the exponential curve fit to a subject’s MP spatial distribution data has been calculated based on MPOD data obtained by heterochromatic flicker photometry, HFP (Nolan et al 2008; Kirby et al 2010) and by twowavelength FAF (Hammond et al 2012). This integrated MPOD value provides information as to the overall quantity of MP presents across the macula as opposed to measurements at a single retinal eccentricity. This is a useful indicator to consider as it has been shown that the overall amount of MP present varies according to its density distribution pattern (Trieschmann et al 2003)

Methods

Results

Discussion

Conclusion