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Relationship between optic disc ovality and horizontal disc tilt in normal young subjects
Hiroko Takasaki1, Tomomi Higashide, Hisashi Takeda
1Department of Ophthalmology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa 920-8641, Japan.
Purpose:
To investigate the relationship between optic disc ovality and horizontal disc tilt.
Methods:
The ovality index (the ratio of minimum to maximum disc diameter), horizontal and vertical optic disc tilt, and optic disc torsion were measured on the Heidelberg Retina Tomograph 3 printout in 381 right eyes of 381 normal young subjects. Stereophotographically obvious horizontal tilt and the relationship between the ovality index and horizontal tilt were determined in non-torted discs with an absolute value of disc torsion ≤15°.
Results:
The median values of the ovality index, horizontal and vertical tilt, and disc torsion in all subjects were 0.92, 9.0°, 0.0°, and 0.0°, respectively. In the non-torted discs (205 eyes, 53.8 %), a horizontal tilt of ≥20° was stereoscopically obvious. The ovality index was significantly correlated with horizontal tilt (r = -0.276, P < 0.001). The area under the receiver operation curve for the ovality index to discriminate a disc with a horizontal tilt of ≥20° was 0.861. The horizontal disc tilt was significantly correlated with spherical equivalent (r = -0.369, P < 0.001) and axial length (r = 0.277, P < 0.001), but the ovality index was not.
Conclusions:
Although the ovality index may be an indicator of stereoscopically obvious horizontal disc tilt, horizontal tilt is more closely related with myopia.
