September 2011
Volume 52, Issue 10
Letters to the Editor  |   September 2011
Variability in Subfoveal Choroidal Thickness Measurements
Author Affiliations & Notes
  • Kamron N. Kahn
    St. James University Hospital, Leeds, United Kingdom; and
  • Martin McKibbin
    St. James University Hospital, Leeds, United Kingdom; and
  • Rehna S. Kahn
    Calderdale Royal Hospital, Halifax, United Kingdom.
Investigative Ophthalmology & Visual Science September 2011, Vol.52, 7221. doi:
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    • Get Citation

      Kamron N. Kahn, Martin McKibbin, Rehna S. Kahn; Variability in Subfoveal Choroidal Thickness Measurements. Invest. Ophthalmol. Vis. Sci. 2011;52(10):7221.

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      © ARVO (1962-2015); The Authors (2016-present)

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The recent report by Rahman et al. 1 describing subfoveal choroidal thickness (SFCT) measurements was interesting to read and raised several questions that further interpretation of their data may answer. The range of thicknesses (OD 172–550 μm; OS 142–563 μm) seems surprisingly large for the age range of their study participants. Using the formula for age-adjusted SFCT measurements of Margolis and Spaide 2 (366 − 1.56 × age in years) one could expect a range on the order of 290 to 320 μm. 2 In their original paper, Margolis and Spaide do not specify the ethnicity of the patients examined but one hypothesis could be that racial differences account for such variability in the current work. Although not primarily designed to test this effect, did the authors see any trend to support or refute it? Similarly, for the outliers presented in the Bland-Altman plots, was there any suggestion of a racial predilection? Is the sclerochoroidal interface more difficult to detect in some groups compared with others? 
As the choroid is a highly vascular structure, blood flow and thickness are known to vary with intraocular pressure, vascular perfusion pressure, 3 and circulating endogenous catecholamines (and by inference, presumably, anxiety state). 4 Were any of these factors controlled for? 
Rahman W Chen FK Yeoh J Patel P Tufail A Da Cruz L . Repeatability of manual subfoveal choroidal thickness measurements in healthy subjects using the technique of enhanced depth imaging optical coherence tomography. Invest Ophthalmol Vis Sci. 2011;52(5):2267–2271. [CrossRef] [PubMed]
Margolis R Spaide RF . A pilot study of enhanced depth imaging optical coherence tomography of the choroid in normal eyes. Am J Ophthalmol. 2009;147(5):811–815. [CrossRef] [PubMed]
Kiel JW van Heuven WA . Ocular perfusion pressure and choroidal blood flow in the rabbit. Invest Ophthalmol Vis Sci 1995;36:579–585. [PubMed]
Chou PI Lu DW Chen JT . Adrenergic supersensitivity of rabbit choroidal blood vessels after sympathetic denervation. Curr Eye Res 2001;23:352–356. [CrossRef] [PubMed]

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