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A. Diniz Filho, S. Cronemberger, R. V. Mérula, N. Calixto; Comparative Study Between Plateau Iris Configuration and Primary Open Angle Glaucoma with Narrow Angle Using Ultrasound Biomicroscopy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3363.
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© ARVO (1962-2015); The Authors (2016-present)
To compare topologic features between eyes of patients with plateau iris configuration (PIC) and eyes of patients with primary open angle glaucoma with narrow angle (POAGNA), and to identify any characteristics that could contribute to clarify the importance of the plateau iris component in the mechanism of angle closure.
Twenty eyes of 11 patients with PIC and 45 eyes of 27 patients with POAGNA were prospectively examined by ultrasound biomicroscopy (UBM) under light and dark conditions. All eyes were examined in the superior (SQ) and inferior (IQ) quadrants. Measurements of the following UBM parameters were done and compared between the two groups: anterior chamber depth (ACD); iris-lens contact distance (ILCD); angle opening distance at 250 µm (AOD250) and 500 µm (AOD500) from the scleral spur; trabecular-ciliary process distance (TCPD); iris-ciliary process distance (ICPD); iris thickness measured along the same line as the TCPD (ID1); iris-zonule distance (IZD); iris thickness measured 2 mm from the iris root (ID2); and the maximum iris thickness near the pupillary edge (ID3).
Statistically significant differences between PIC and POAGNA eyes under light and dark examinations were found in ACD, P = 0.003; ILCDSQ, P < 0.001; TCPDSQ light, P = 0.020; TCPDSQ dark, P < 0.001; ICPDSQ, P < 0.001; IZDSQ light, P = 0001; IZDSQ dark, P = 0,021; ILCDIQ, P < 0.001; TCPDIQ, P < 0.001 ICPDIQ, P < 0.001; and IZDIQ light, P < 0.001. The iris thickness was similar in PIC and POAGNA eyes in both superior and inferior quadrants, except for ID3SQ and ID3IQ both in light and dark conditions that showed statistically significant differences (respectively P = 0.001, P < 0.001, P = 0,021 and P = 0.003). Statistically significant differences between light and dark examinations of PIC eyes were also found in the IZDSQ (P = 0.033) and ID3SQ (P = 0.038), and in POAGNA eyes in the ILCDSQ (P = 0.013), AOD250SQ (P = 0.034), AOD500SQ (P = 0.008), ICPDSQ (P = 0.046), ID1SQ (P = 0.037), ID3SQ (P = 0.047), and ILCDIQ (P < 0.001).
Eyes with PIC presented a shallower ACD in comparison to eyes with POAGNA. The ILCD was significantly higher in PIC group. The TCPD, ICPD, IZD and ID3 were significantly higher in POAGNA group. When the illumination conditions were changed from light to dark ILCD, AOD250 and AOD500 decreased in POAGNA group.
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