Study of optic radiations in patients with primary open-angle glaucoma with diffusion tensor imaging

Abstract

Objective: To study the alteration of the optic radiations in patients with primary open-angle glaucoma (POAG) by diffusion tensor imaging (DTI) and tractography, and to reveal the correlation between the DTI derived parameters and the severity of the disease. Methods: A total of 24 patients with POAG and 20 age- and gender-matched healthy controls were enrolled in this study from January 2011 to June 2013.All subjects underwent ophthalmoscopy, standard automatic perimetry, intraocular pressure measurement and MRI scanning.All the eyes of POAG patients were evaluated by Hodapp-Anderson-Parrish (HAP) system.Then the stages of bilateral eyes were added together to evaluate the disease severity.Tractography was used to measure the fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) of the optic radiations of these subjects.The results of the two groups were compared.Partial correlation was then used to reveal the correlation between these derived DTI parameters and the severity of POAG. Results: Compared with health controls, POAG patients showed significant decreased FA (t=-3.299, P=0.002) and AD (t=-2.485, P=0.013), increased RD (t=2.365, P=0.018) in optic radiation .The alteration of MD was not significant (t=0.719, P=0.454). Mean FA values of the optic radiations were negatively correlated with POAG stages (r=-0.643, P= 0.001), while mean RD values (r=0.570, P= 0.004) and mean MD values (r= 0.448, P= 0.028) were positively correlated with POAG stages.No correlation between AD values and severity of POAG was found. Conclusion: In the optic radiations of POAG patients, the FA values and AD values decrease, while RD values increase, indicating the fiber integrity changes.The alterations of FA, RD and MD are correlated with disease severity.