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J. Wang, A. A. Kamdeu Fansi, D. Descovich, IV, P. J. Harasymowycz, G. Li, M. R. Lesk; Relationships Between Asymmetric Glaucomatous Visual Field Loss and Ocular Biomechanical Factors in Open-Angle Glaucoma. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4884.
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To assess the influence of ocular biomechanical factors on the interocular asymmetry of visual field (VF) damage in patients with open-angle glaucoma (OAG).
Cross-sectional study. Patients with diagnosis of primary open-angle glaucoma (POAG) or OAG secondary to pseudoexfoliation syndrome (PXG) were included. In one single session, the following data for both eyes of each patient were obtained: mean deviation (MD) from most recent and reliable VF (Humphrey SITA-Standard 24-2), historical maximum IOP (IOPmax), current treated IOP (IOP), corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), axial length (AL) and ocular pulse amplitude (OPA) using dynamic contour tonometer. Ocular wall stress (WallS) for each eye was also calculated using Laplace’s equation. Correlation analysis was performed between the interocular difference in MD (dMD) and the interocular difference of various mechanical factors measured in the session. We systematically used the value of right eye (OD) to minus the value of left eye (OS). For example, a negative dMD signifies that OD is more damaged and a positive dMD signifies that OD is less damaged than OS. Similarly, a negative dIOPmax signifies that OD had a lower historical IOPmax than OS.
A total of 102 patients with OAG were included (99 POAG; 3 PXG). The average age was 64.8 SD 9.4 years old. The average interocular MD difference in absolute value was 4.62 SD 5.4 dB (range: 0.03, 28.68). When we systematically used MD of OD to minus MD of OS, the average difference in MD (dMD) was - 1.07 SD 7.04 dB (range: - 28.68, 24.53). This difference (dMD) correlated significantly with the difference in IOPmax (R = -0.327, p = 0.001), the difference in calculated WallS (R = - 0.371, p < 0.001), the difference in CCT (R = 0.220, p = 0.03), and the difference in AL ( R = - 0.233, p = 0.02). The dMD did not correlate significantly with the difference in OPA, CH (R = 0.179, p = 0.07) and in CRF (R = - 0.116, p = 0.25).
In patients with POAG and PXG, the asymmetrical VF findings were found to be related to historical IOP, AL, wall stress calculated by Laplace’s equation and CCT. Higher historical IOP, wall stress, and longer AL predispose the eye to more VF damage, whereas a thicker CCT is associated with less VF damage.
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