On OCT images taken in gas-filled eyes, anatomical structures were shown to be significantly smaller than their actual size. In their interesting study, Yamashita et al. from Kagoshima University showed that on the OCT images taken in gas-filled eyes anatomical structures are significantly smaller than their actual size. The authors obtained this important finding, which they named as the “minification effect of OCT”, as a result of the examination of 81 eyes that had gas tamponade for macular hole surgery. It was found that the vertical and horizontal diameter of the optic nerve in the presence of gas was approximately 25% smaller than after the gas resorbtion. In terms of average disk area, the difference reaches 40%.
Yamashita T, Terasaki H, Sakamoto T. Minification of fundus optical coherence tomographic images in gas-filled eye. BMC Ophthalmol. 2016;16:124.