Inter-eye Comparison of the Lamina Cribrosa Depth in Patients with Bilateral Normal-tension Glaucoma with Asymmetrical Damage

Purpose: To evaluate the association between lamina cribrosa depth (LCD) and the severity of glaucomatous damage in patients with normal-tension glaucoma (NTG).Methods: The optic nerve heads (ONHs) of patients with bilateral NTG showing asymmetrical damage were scanned using spectral-domain optical coherence tomography. LCDs were measured on ONH horizontal B-scan images at three locations equidistant across the vertical optic disc diameter and compared between the more damaged and contralateral eyes. Conditional logistic regression analysis was performed to identify ocular risk factors associated with more severe damage between the eyes.Results: One hundred and four eyes of 52 patients with bilateral NTG were included. The mean age was 66.0 ± 15.0 years; there were 31 males and 21 females. The more damaged eyes exhibited a higher baseline intraocular pressure (IOP) (p < 0.001), a thinner global retinal nerve fiber layer thickness (p < 0.001), and worse visual field mean deviation (p < 0.001) and a pattern standard deviation (p < 0.001), than the contralateral eyes. In contrast, we found no significant inter-eye difference in either the spherical equivalent or the axial length. The average LCD was significantly larger in the more damaged eyes (529.4 ± 116.7 vs. 482.9 ± 107.5 μm, p < 0.001). On conditional logistic regression analysis, the higher the baseline IOP (p = 0.006) and the larger the LCD (p = 0.003), the higher the risk of having more severe damage compared to the contralateral eye under similar systemic conditions.Conclusions: The LCD was significantly larger in the more damaged eyes of patients with bilateral NTG, suggesting that LC deformation might be associated with glaucomatous ONH damage in NTG eyes.