Wednesday, 9 September 2015

Use a machine and get the same result....magic

Oberwahrenbrock T, Weinhold M, Mikolajczak J, Zimmermann H, Paul F, Beckers I, Brandt AU.
Reliability of Intra-Retinal Layer Thickness Estimates. Purpose: PLoS One. 2015 Sep 8;10(9):e0137316. doi: 10.1371/journal.pone.0137316

Measurement of intra-retinal layer thickness using optical coherence tomography (OCT) has become increasingly prominent in multiple sclerosis (MS) research. Nevertheless, the approaches used for determining the mean layer thicknesses vary greatly. Insufficient data exist on the reliability of different thickness estimates, which is crucial for their application in clinical studies. This study addresses this lack by evaluating the repeatability of different thickness estimates.
METHODS:Studies that used intra-retinal layer segmentation of macular OCT scans in patients with MS were retrieved from PubMed. To investigate the repeatability of previously applied layer estimation approaches, we generated datasets of repeating measurements of 15 healthy subjects and 13 multiple sclerosis patients using two OCT devices (Cirrus HD-OCT and Spectralis SD-OCT). We calculated each thickness estimate in each repeated session and analyzed repeatability using intra-class correlation coefficients and coefficients of repeatability.
RESULTS:We identified 27 articles, eleven of them used the Spectralis SD-OCT, nine Cirrus HD-OCT, two studies used both devices and two studies applied RTVue-100. Topcon OCT-1000, Stratus OCT and a research device were used in one study each. In the studies that used the Spectralis, ten different thickness estimates were identified, while thickness estimates of the Cirrus OCT were based on two different scan settings. In the simulation dataset, thickness estimates averaging larger areas showed an excellent repeatability for all retinal layers except the outer plexiform layer (OPL).
CONCLUSIONS:Given the good reliability, the thickness estimate of the 6mm-diameter area around the fovea should be favored when OCT is used in clinical research. Assessment of the OPL was weak in general and needs further investigation before OPL thickness can be used as a reliable parameter.

Today's dreaded meta-analysis is to look at optical coherence tomography machine to see if they get the same thicknesses of the retinal fibre layers.. It says there was good reliability and it was 6mm. I should hope there was good reliability, because the retinal nerve layer thickness is calculated automatically by the machine and therefore you would demand that it is consistent if the algorithm is of any use.

PlosOne policy is pay to publish and as long as the work is methologically sound, it is OK. Apparently it gets about 5,000 papers a week and publishes about 30,000 a year and at a cost of about £1,000 a paper, not a bad little earner for maintaining a repository attached to the internet,

1 comment:

  1. Well I it is encouraging that good reliability was found. Without studies we wouldn't know.


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