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Syogo Arimura, Yoshihiro Takamura, Takeshi Tomomatsu, Yuji Takihara, Masaru Inatani; Determinants of angle narrowing after mydriasis. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2264.
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© ARVO (1962-2015); The Authors (2016-present)
Recent findings indicate lens vault (LV) is a contributing factor for the narrow angle. We analyzed the change of the anterior chamber components after mydriasis noninvasively and accurately using anterior segment optical coherence tomography (ASOCT), and investigated to identify the risk factor of angle narrowing.
We prospectively conducted angle analysis with AS-OCT before and at 30 minutes after pupil dilation with eye-drops of 0.5% tropicamide and 0.5% phenylephrine hydrochlorid under dark condition (< 1 lux). The parameters included axial length (AL), angle opening distance at 500 or 750μm from scleral spur (AOD500, AOD750), angle recess area (ARA), trabecular iris space area (TISA), anterior chamber depth (ACD) and LV. Univariate and multivariate linear regression modeling were performed to assess the relationship between the change of AOD500 (ΔAOD500) and the ocular biometric or systemic parameters (age, height, gender). A stepwise selection regression was used to identify sequentially the contribution of each independent variable.
A total of 103 Japanese subjects (71.5 ± 12.4 years; mean ± S.D.) were enrolled. After univariate analysis, eyes with more decreased ΔAOD500 showed significantly older age (P<0.001), shorter AL (P=0.001), shorter height (P=0.005), greater LV (P<0.001), and smaller values of AOD500 (P=0.021), AOD750 (P<0.001), ARA (P=0.025), TISA (P=0.007) and ACD (P=0.004). In the multivariate analysis, more decreased AOD500 was significantly associated with older age (P=0.013), greater LV (P=0.004), and smaller AOD500 (P=0.004) and smaller AOD750 (P=0.014). The stepwise linear regression analysis revealed that the strong determinants of ΔAOD500 were LV (partial R2=0.222; P<0.001) and age (partial R2=0.095; P<0.001). The total of two factors explained 31.7% of the variability of ΔAOD500.
This study revealed that greater LV and older age are independently associated with the angle narrowing after mydriasis. After mydriasis, LV is the primary determinant of angle narrowing.
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