Purchase this article with an account.
David B Elliott, Alex A Black, Joanne M Wood; Oblique astigmatism increases Subjective Visual Vertical errors. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4760. doi: https://doi.org/.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Verticality perception as measured using Subjective Visual Vertical (SVV) is commonly used to diagnose and monitor patients with vestibular and CNS lesions and poor SVV is linked with dizziness. SVV is thought to be controlled principally by the vestibular system, with minor input from the somatosensory and visual systems. We hypothesised that magnification changes from oblique astigmatic refractive correction could adversely affect SVV.
Static and dynamic SVV was measured in 15 participants (mean age 42 ± 23 years) with no ocular disease and normal levels of visual function and without vestibular, CNS disease or history of dizziness. SVV and Freiburg visual acuity (VA) was measured under the following seven conditions in a random order: participants’ habitual refraction correction with working distance lens, with additional trial case cylinders of +1.00/-2.00 at axes 90, 180 and 45 degrees and with an additional astigmatic -3.5% size lens at axes 90, 180 and 45 degrees.
Mean ± 1 SD static and dynamic SVV errors were -0.3 ± 1.4 and 2.4 ± 2.8 degrees. These were increased with oblique cylinder to 1.0 ± 1.3 (p<0.001) and 3.2 ± 3.3 degrees (p=0.01) respectively. The oblique astigmatic size lens increased static and dynamic SVV to 0.7 ± 1.2 and 3.9 ± 3.5 degrees (p<0.001). For 13 of the 15 individual participants, static and dynamic SVV increased with the oblique cylinder and size lens. There were minimal changes with with-the-rule and against-the-rule astigmatism. The results cannot be due to different effects of the lenses on VA as the cylindrical lenses at axes 90, 180 and 45 caused similar reductions in visual acuity (0.30±0.15, 0.26±0.13, 0.32±0.13 logMAR) as did the astigmatic size lens at axes 90, 180 and 45 degrees (-0.05±0.14, -0.07±0.13, -0.06±0.11 logMAR). Mean habitual VA was -0.11 ± 0.07 logMAR.
Both static and dynamic SVV were increased by oblique astigmatism as induced by a cylinder and size lens, but not by with-the-rule or against-the-rule astigmatic changes. The results are likely due to oblique magnification effects. These increases in SVV errors by oblique astigmatism may help explain why changes in oblique astigmatic refractive correction can contribute to increased dizziness symptoms (Supuk et al., OPO 2016).
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
This PDF is available to Subscribers Only