Development of Optic Disc Torsion in Children

To document the development of disc torsion.

Consecutive disc photographs obtained at an interval of at least 1 year were reviewed retrospectively in 173 eyes of 173 Korean children. The angle of the vertical disc axis (AVDA) was measured in each fundus photograph with the fovea-disc center axis set at 0°. The associated change in the morphology of the optic disc was assessed by measuring the ratio of the horizontal to vertical disc diameters and the ratio of the maximum parapapillary atrophy width to vertical disc diameter. Eyes were divided into two groups with respect to the development of disc torsion: torsion and non-torsion group. Progressive torsion was defined as a change in AVDA between baseline and follow-up photographs beyond the coefficient of intraobserver repeatab ility. Factors associated with optic disc torsion were evaluated using logistic regression analysis.

Mean subject age and refractive error at the time of baseline fundus examination were 6.8 ± 1.7 (range, 2 to 11) years and 0.2 ± 2.6 (range, -6.0 to +5.5) diopters, respectively. Mean follow-up period was 44.8 ± 21.1 (range, 12 to 103) months. Forty-two eyes (24%) were classified as torsion group who showed changes in AVDA that were greater than the intraobserver measurement variability (4.5°) during the follow-up period. The development of optic disc torsion was associated with greater myopic shift, a decrease in horizontal to vertical disc diameters, and an increase in parapapillary atrophy width to vertical disc diameter.

Progressive optic disc torsion was a common phenomenon in the children included in this study. Torsion occurred as the result of optic disc tilt in an oblique axis in most cases. The findings provide a framework for understanding torsion-related glaucomatous optic nerve damage.