Purpose
Optic disc torsion has become a focus of interest in relation with regional preference of the glaucomatous optic nerve damage in myopic eyes with torted optic disc. In addition, its effect on detecting glaucomatous damage based on the measurement of the circumpapillary retinal nerve fiber layer thickness or minimal rim width remains to be determined. Understanding the nature of optic disc torsion may provide important implications for investigating the regional susceptibility of the optic nerve in eyes with disc torsion, and also in relation with correcting the effect of torsion when diagnosing glaucomatous damage using imaging devices. This study was conducted to describe development of torted appearance of the optic disc observed in children.
Methods
Serial fundus photographs taken at intervals of 1 year or more from 201 eyes of 201 Korean children were reviewed. The angle of the long optic disc axis (ALDA) was measured on each fundus photographs with the fovea-disc center axis set at 0 degree. The morphologic change of the optic disc was assessed by measuring the ratio of the short to long disc diameter (SLDR) and the ratio of the maximum parapapillary atrophy (PPA) width to vertical disc diameter (PVDR).
Results
Mean subject age and refractive error at the time of baseline fundus examination were 7.2 ± 1.8 years (range, 3 - 13 years) and -0.2 ± 3.1 Diopters (range, -10.0 - +8.5 Diopters), respectively. Mean follow-up period was 39.3 ± 20.2 months (range, 12-111 months). Ninety-one eyes showed changes in the ALDA greater than intraobserver measurement variability (4.5 degree) during the follow-up. Eyes with significant ALDA change were associated with myopic shift, decrease of the SLDR and increase of PVDR. There was a significant correlation between the direction of ALDA change and the angle of maximum PPA width measured at final follow-up (r= 0.886, P < 0.001).
Conclusions
Progressive optic disc torsion was a common phenomenon among children. The torsion occurred as a combination of optic disc axis rotation and disc tilt in the oblique direction, being accompanied by the development/enlargement of PPA.