Abstract
Purpose :
Considering the results of population-based studies that IOP is a risk factor for normal tension glaucoma (NTG) and the fact that intraocular pressure (IOP) reduction can reduce the risk of the disease progression, IOP-related mechanical stress likely plays a role in the pathogenesis of the disease even in statistically normal IOP levels. On the assumption that IOP induced posterior bowing of laminar cribrosa (LC) may represent mechanical strain of LC leading to glaucomatous damage, we investigated the inter-eye differences in the degree of LC curve between the glaucomatous and the fellow healthy eyes in unilateral NTG patients.
Methods :
This study was approved by the Seoul National University Bundang Hospital Institutional Review Board and conformed to the Declaration of Helsinki. We analyzed cross-sectional data of 76 eyes of 76 treatment-naive unilateral NTG patients from the prospective Investigating Glaucoma Progression Study. The participants underwent enhanced depth imaging (EDI) volume scanning of the optic nerve head at baseline examination. The magnitude of LC curve was assessed by measuring LC curve index (LCCI) at 7 locations spaced equidistantly across the vertical optic disc diameter together with LC depth (LCD). The relationship between the degree of LCCI and presence of glaucoma was analyzed, and the factors associated with the presence of glaucoma were determined.
Results :
Eyes with NTG had larger LCCIs than contralateral healthy eyes at all locations (P < 0.001). In univariate conditional logistic regression analysis, higher baseline IOP (P = 0.010), higher myopia (P = 0.021), deeper LCD (P = 0.007), and larger LCCI (P < 0.001) were associated with the presence of glaucoma. In multivariate analysis, larger LCCI was revealed as a significant factor associated with the presence of glaucoma (P < 0.001).
Conclusions :
The glaucomatous eyes had more steeply curved LC than fellow healthy eyes. Moreover, higher LCCI was significantly associated with the presence of glaucoma. In light of mechanical theory of glaucoma, this finding supports that LC strain contributes to the pathogenesis of NTG.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.