A new device to assess static ocular torsion

In clinical settings, static ocular torsion is assessed by taking a fundus photograph and measuring the angle between a horizontal line and the line connecting the fovea to the head of the optic nerve (centro-cecal axis rotation; CCAR). We developed and tested a system specifically aimed at CCAR measurements, based on low-cost commercial hardware, and that implements an adaptive research algorithm that selects and presents bright dots on a monitor to outline the borders of the blind spot, locate its center, and measure CCAR. We examined 10 healthy subjects who underwent four CCAR measurements to evaluate the reliability of the system and compared our results with those of fundus photographic examination. Our data showed an excyclophoria, with mean ocular torsion of 6.4° in the right and 6.7° in the left eye. These values are in keeping with those in the literature. Moreover, the values of the intraclass correlation coefficients suggest excellent reliability of the technique.