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Paul F Stetson, Ali M Allahdina, Susan Vitale, Catherine Cukras; Optical Coherence Tomography Minimum Intensity Abnormalities in Hydroxychloroquine Toxicity. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4246. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
This study is to demonstrate visualization of outer retinal disruption in hydroxychloroquine toxicity using en-face optical coherence tomography (OCT) minimum-intensity projection and to measure the repeatability of the minimum-intensity (MI) measurement.
Data from 132 eyes from 66 patients who had been treated with hydroxychloroquine were gathered from the Cirrus HD-OCT system. These image volumes were processed offline to create en-face images using the minimum intensity of the speckle-reduced image between the ILM and RPE segmentations. Depths of the minima were also viewed in selected B-scans. The repeatability of the minimum intensity was also assessed on 9 eyes from 9 patients where data were available for more than two scans with Signal Strength of 5 or above.
Elevated levels of OCT minimum intensity were found in cases of hydroxychloroquine toxicity, whereas cases that did not develop toxicity had relatively low MI. In areas of relatively low MI, the minimum was located in the outer nuclear layer or Henle fiber layer. In areas of greater outer retinal disruption, the minimum was displaced into the inner nuclear layer. Subfield-median values of the MI had a range of 45.0 to 52.6, with a range of measurement errors of 1.02 to 1.99. The Inner Inferior subfield had a mean median MI of 51.7, with a measurement error of 1.33.
The minimum-intensity projection allows visualization of outer retinal disruption in hydroxychloroquine toxicity with good repeatability. The retinal layer in which the minima are located may also be an indicator of outer retinal disruption.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Moderate case of toxicity. (top) B-scan showing location of minima. (bottom) stripes showing raw and normalized minimum intensities for each A-scan. This scan shows disruption of the IS/OS junction and pattern of increased minimum intensity approximately 1 mm from the fovea, accompanied by displacement of the minimum into the INL.
En-face view of minimum intensities for same case of moderate toxicity. Visual acuity in this eye was 20/20, with no evidence of fundus changes or FAF abnormalities. mfERG showed increased R1/R2 ratio 3.3.
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