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Mi Sun Sung, Sang Woo Park, Jee Myung Yang, Department of Ophthalmology, Chonnam National University Medical School and Hospital; Characteristics of Optic Disc Torsion in Young Myopic Eyes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1008.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the characteristics of optic disc torsion and the eye-related factors affecting optic disc torsion in normal young myopic eyes.
We performed a comparative and cross-sectional study including 220 normal myopic eyes without retinal nerve fiber layer (RNFL) defect (spherical equivalent (SE) more than -0.50 D). SE refractive error, axial length (AXL), central corneal thickness (CCT) and intraocular pressure (IOP) were evaluated and optic disc tilt ratio (ratio of maximum to minimum disc diameter), optic disc torsion degree, optic disc area, β-zone parapapillary (PPA) area, rim area and cup-disc ratio was measured from fundus photography. Subjects were divided into the superonasal torsion and inferotemporal torsion groups and variables were compared. Univariate and multivariate linear regression analysis were performed to evaluate the relationships of disc torsion degree with various parameters in each groups.
The mean age of the 220 subjects was 28.68 ± 8.25 years (range, 20 to 40) and the mean SE and AXL were -4.58 ± 2.66 D and 25.76 ± 1.47 mm, respectively. Among the 220 subjects, 147 showed superonasal disc torsion and 73 showed inferotemporal disc torsion. The mean tilt ratio and the degree of torsion were 1.16 and 19.81° in the superonasal torsion group, and 1.20 and 28.93° in the inferotemporal torsion group, showing significant differences between the groups (P = 0.028 and 0.006, respectively). There were also significant difference in IOP, SE, AXL and PPA area between the two groups (P = 0.043, <0.001, <0.001 and <0.001, respectively). In the superonasal torsion group, we found no significant associations between the torsion degree and various parameters in univariate and multivariate analysis. However. in the inferotemporal torsion group, using multiple linear regression analysis, greater torsion was independently related to a higher IOP (P < 0.001).
In young myopic eyes without RNFL defect, the superonasal disc torsion was more prevalent than the inferotemporal disc torsion. And in particular, higher IOP was significantly correlated with the higher inferotemporal torsion. Our findings suggest that IOP could be considered as important factor affecting optic disc torsion in young myopic eyes.
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