Primary Acute Angle-Closure Glaucoma: Three-Dimensional Reconstruction Imaging of Optic Nerve Heard Structure in Based on Optical Coherence Tomography (OCT)

Abstract

BACKGROUND In glaucoma, the cup to plate ratio enlargement is a recognized pathological phenomenon. At present, the research on optic nerve in China and abroad mainly focuses on 2-dimensional research, and the measurement of 3-dimensional volume data is less well studied. Therefore, the recognition of 3-dimensional morphological changes is conducive to timely clinical intervention to prevent or slow down progressive vision loss. MATERIAL AND METHODS In this paper, optical coherence tomography (OCT) volume imaging technology was used to analyze and compare the morphological changes of primary acute angle-closure glaucoma in three-dimensional morphology, reconstruct the volume data of three-dimensional optic nerve head (ONH), and make morphological measurements. RESULTS The rim width of the glaucoma group was significantly lower than that of the control group, and the average volume and intraocular pressure of the optic cup were significantly increased (P<0.05), while the rim width and intraocular pressure of the other group were not significantly changed (P>0.05). CONCLUSIONS We used three-dimensional reconstruction to identify OCT images between glaucoma patients and the control group with significant differences.

Figure 1

The processing of OCT images. (A) Raw image of the ONH. The bottom figure is the profile of the white line in the top OCT image. Obvious noise is shown. (B) The processed filtered image shows increased SNR, but the image still lacks contrast. (C) The processed image (by med-filter and CLAHE), with significantly improved contrast and gray level. The SNR was increased in the profile. OCT – optical coherence tomography; ONH – optic nerve head; SNR – signal to noise ratio; CLAHE – contrast limited adaptive histogram.

Figure 2

The 3D volume of the ONH and 3D view of the NCO marker. (A) Top view of the 3D volume of the ONH. (B) Side view of the ONH, with the 3D ONH clearly countered and complete in 3D form. Every measurement mark can be located in the real voxel of the ONH volume. (C) The 3D view of the NCO. The yellow color marks the RPE/BM and blue designates the narrowest NCO. 3D – 3-dimensional; ONH – optic nerve head; NCO – neural canal opening; RPE/BM, RPE – retinal pigment epithelium/Bruch’s membrane.

Figure 3

The reference points used to measure the morphology of the ONH. The width of the NCO is indicated by the green line joining the top and inner edges of the RPE. The reference plane was determined by tracing a line parallel to the NCO width plane with an offset of 0.1500 mm (white line). On this reference plane, the internal diameter of the rim edge was the cup diameter (width). The N-NCO was determined by the innermost and inward fold point of the choroid. ONH – optic nerve head; NCO – neural canal opening; N-NCO – narrowest neural canal opening; RPE – retinal pigment epithelium.

Figure 4

The relationship between the parameters of ONH and IOP. (A) Analysis of changes in intraocular pressure values between glaucoma and normal eyes with rim width. (B) Analysis of changes in intraocular pressure values between glaucoma and normal eyes optic cup volume. It can be seen that the rim width is negatively correlated with the intraocular pressure value (r=−0.579, P<0.001) and the optic cup volume is positively correlated with intraocular pressure(r=0.536, P<0.01). ONH – optic nerve head; IOP – intraocular pressure.