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R. V. Merula, S. Cronemberger, A. Diniz Filho, N. Calixto; Biometric Comparative Study Between Acute Primary Angle Closure and Primary Open Angle Glaucoma With Narrow Angle. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5099. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare keratometry (K), central corneal thickness (CCT), lens thickness (LT), lens position (LP), relative lens position (RLP), axial length (AL) and anterior chamber depth (ACD) among affected and fellow Acute Primary Angle Closure (APAC) eyes and Primary Open Angle Glaucoma with Narrow Angle (POAGNA) eyes, and to identify any characteristics that could predict an acute episode.
30 unilateral APAC patients and 30 POAGNA patients were prospectively evaluated. After clinical control of the acute episode, and before surgical procedures, both eyes of APAC subjects, and one eye of POAGNA subjects were assessed biometrically (A-mode and ultrasonic pachymetry). LP was defined as ACD + 1/2LT and RLP as LP/AL. Three variables (K, CCT and LT/AL) that the differences between APAC fellow and POAGNA eyes were statistically significant were used to build a logistic regression model (LRM), aimed to predict the risk of APAC. Receiver operating characteristic (ROC) curves of the LRM and the parameters that statistical differences were found between APAC fellow and POAGNA eyes were elaborated.
APAC-affected eyes had higher average K value than fellow (P = 0.027) and POAGNA eyes (P = 0.010), and the average K value of fellow eyes was higher than POAGNA eyes (P = 0.036). There was no difference between APAC-affected and fellow eyes when CCT was evaluated (P = 0.571). However, POAGNA eyes demonstrated lower CCT than APAC-affected (P = 0.015) and fellow eyes (P = 0.023). Biometric difference between APAC-affected and fellow eyes was found only in the LP (P = 0.046). When fellow eyes were compared to POAGNA eyes, statistical differences were found in ACD (P = 0.006), AL (P = 0.014), and LT/AL (P = 0.003). The comparison between APAC-affected and POAGNA eyes showed significant differences in almost all biometric parameters, except for LT (P = 0.085) and RLP (P = 0.278). After assessment of ROC curves and optimal balance between sensitivity and specificity, we found that LRM model higher than 0.512 could be a good indicator for prophylactic laser iridotomy (LI) among patients with narrow angle, and LT shorter than 22.57 mm and LT/AL higher than 2.09 could be al least reasonable.
This study showed that APAC-affected and fellow eyes have similar biometric features, and POAGNA eyes have a less crowded anterior segment. The LRM built showed promising results and could be another indicator for prophylactic LI. Longitudinal comparisons are required to find other parameters that can accurately predict an attack.
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