My comments with attached images of the problem are not being published for some reason, so I'll copy only the text here...
Thanks for your reply. However, what I'm referring to is not caused by the refresh rate. Even when putting a static white background on the HMD, we see that the pixels are being strobbed (that is, the luminance is oscillating between white and black at 90 Hz rather than staying constant). Please see the image attached below as an example. You can see the brightness over time for both screens (1sec total duration) for a constant white background. This is not related to the image refreshing, as with a static white background the luminance would just stay constant. This is related instead to the image persistence being less that the duration of the frames of ~11ms. This is a common technique used to reduce motion blur in digital displays, particularly for gaming applications; however there is normally a setting for turning this off. We would like to know if such setting exist, or any other way of turning this feature off.