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Shinichiro Nakano, Takahiro Hiraoka, Yumi Hasegawa, Tetsuro Oshika; Effect Of Monocularly And Binocularly Induced Astigmatic Blur On Stereopsis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1778.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the effect of monocularly and binocularly induced astigmatism on stereopsis.
Twelve normal volunteers (31.2 ± 5.2 [mean ± SD] years) with spherical equivalent refraction between 0 and -6.00 diopters (D), refractive astigmatism up to 0.75 D were enrolled. After correcting each refractive error by spectacles, against-the-rule (ATR) or with-the-rule (WTR) astigmatism was intentionally produced in both eyes in three steps ( +1.0, +2.0 and +3.0D)in random order, and stereoacuity was evaluated by using 9 circular-quadruplet targets (20 ~ 400 arc seconds) of OPTEC Vision Tester 6500 (Stereo Optical Co, Inc.). The cylindrical addition of different powers (+1.0 ~ +3.0D) was compensated with spherical lenses to achieve zero spherical equivalent refraction. These examination was repeated with monocularly astigmatic induction (i.e.; no astigmatism in fellow eye).
The mean stereoacuity (log arc seconds) in each condition was 1.59 ± 0.19 for binocular WTR, 1.47 ± 0.16 for monocular WTR, 1.49 ± 0.14 for binocular ATR, and 1.50 ± 0.19 for monocular ATR astigmatism at 1D induction. At 2D induction, it was 2.06 ± 0.35, 1.96 ± 0.31, 1.80 ± 0.29, and 1.94 ± 0.29, respectively. At 3D induction, it was 2.41 ± 0.19, 2.22 ± 0.27, 1.96 ± 0.31, and 2.28 ± 0.29, respectively. When compared between binocular and monocular astigmatic induction, there were no significant differences in stereoacuity for ATR astigmatism (p = 0.24 for 1D, p = 0.56 for 2D, and p = 0.28 for 3D, Mann-Whitney U test), and also for WTR astigmatism (p = 0.80, 0.24, 0.14, respectively). When compared between ATR and WTR astigmatism, there were no significant differences in stereoacuity for monocular astigmatic induction (p = 0.84 for 1D, p = 0.93 for 2D, and p = 0.71 for 3D). Similarly, there were no significant differences in stereoacuity between ATR and WTR astigmatism for binocular astigmatic induction up to 2D (p = 0.32 for 1D and p = 0.13 for 2D). However, at 3D induction, stereoacuity in binocular ATR astigmatic defocus was significantly worse than that in binocular WTR astigmatic defocus (p < 0.021). In addition, significant correlations were found between astigmatic power and stereoacuity in all conditions (r = 0.81, p < 0.001 in monocular WTR, r = 0.85, p < 0.001 in binocular WTR, r = 0.81, p < 0.001 in monocular ATR, and r = 0.85, p < 0.001 in binocular ATR astigmatism, Spearman's rank correlation coefficient).
Both binocular and monocular astigmatic induction degraded stereopsis as astigmatic power increased. There were no apparent differences in stereopsis between binocular and monocular astigmatic induction. However, stereopsis seemed to be affected more severely by ATR than WTR astigmatism in binocular and high power astigmatic induction.
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