Acuity and colour vision changes post intravitreal dexamethasone implant injection in patients with diabetic macular oedema - Fig 2

<p><b>CAD results before and after Ozurdex treatment in two subjects with diabetes (A- subject 11; B- subject 4).</b> Both subjects show significant improvement in chromatic sensitivity (i.e., smaller thresholds) post treatment. The grey, dotted lines show the colour limits imposed by the phosphors of the display. Subject B was unable to detect YB colour changes, even for the largest chromatic signals that are limited only by the phosphors of the display with no improvement post treatment. The RG thresholds, on the other hand, show significant improvement post-treatment.</p

CST changes and corresponding correlations with colour vision and VA.

<p>Section A illustrates more clearly the absence of significant changes in YB thresholds when compared to the improvements in RG colour vision. Sections B and C show how the percentage decrease in CST correlates with the corresponding changes in YB (B) and RG (C) thresholds. Section D shows how changes in CST correlate with the changes in LogMAR VA post treatment. A ‘negative’ change indicates an improvement in VA. The results suggest that decreased CST values correlate well with improvement in RG colour vision (r² = 0.43) and VA (r² = 0.34). The YB system, on the other hand, appears to be damaged more severely and shows negligible correlation with the corresponding CST changes (r² = 0.05).</p

RG and YB thresholds.

<p>Shows thresholds measured before treatment in the 14 DMO patients, together with the maximum chromatic saturations that can be produced on the visual display (i.e., the limits of colour saturation in CAD units that can be generated on the visual display).</p

Screen dumps of CAD test stimuli and template plot.

<p>Section A shows stimulus colours that isolate the RG and YB axes. The mean threshold ellipse measured with respect to a daylight backgroud (CIE- (x, y): 0.305, 0.323) is also shown together with the RG and YB axes and the bespoke keypad employed to record the subject’s responses. Section B shows the standard CAD units for RG and YB colour vision (i.e., the ‘red’ and ‘blue’ arrows) which equal the minor and major axis of the mean threshold ellipse measured for 330 young, healthy normal trichromats [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199693#pone.0199693.ref014" target="_blank">14</a>]. The coloured sysmbols show typical thresholds measured in a subject with normal trichromatic colour vision. Section B, the grey shaded area shows the range of variation expected for young normal trichromats, the innermost and outermost ellipses corresponding to 2.5% and 97.5% confidence limits for normal population, respectively [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199693#pone.0199693.ref018" target="_blank">18</a>]. The dotted black ellipse represents the mean threshold values which define the young standard normal CAD observer. The corresponding mean thresholds are normalised to unity and all other CAD thresholds are expressed in these standard normal units (SNU). Upper normal CAD threshold limits have also been measured as a function of age in a separate study [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199693#pone.0199693.ref020" target="_blank">20</a>]. The smallest colour thresholds correspond to ~ 20 years of age and are followed by a gradual, linear increase of ~ 1% per year for RG and ~ 1.6% for YB, over the remaining life span. Each patient’s thresholds measured in this study were compared against the upper normal threshold limits for the corresponding age [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199693#pone.0199693.ref020" target="_blank">20</a>].</p

Change in RG and YB thresholds, visual acuity and CST.

<p>Change in RG and YB thresholds, visual acuity and CST.</p

Changes in RG and YB colour thresholds following treatment with Ozurdex, plotted for each of the patients examined.

<p>A ‘negative’ percentage change indicates an improvement. It shows little or no improvement in YB colour vision, but a significant improvement in RG colour vision in the majority of patients.</p

Demographic and baseline characteristics of the patients examined in this study.

<p>Demographic and baseline characteristics of the patients examined in this study.</p