ABSTRACT
Objective To establish a three-dimensional (3D) visualization model for the vessel system of rabbit eyes using X-ray phase contrast imaging（XPCI）technique, and observe the morphological characteristics of iris vessels of the rabbit eyes. Methods Angiography on vessels of the New Zealand rabbit eyes was conducted using Barium sulfate as the contrast medium. The projected images of in vitro rabbit eye samples with high precision were obtained by XPCI technique, and then converted to tomography images by filter back projection. The 3D reconstruction of the rabbit eyes was completed by commercial visualization software Amira 5.2.2. Results The main blood vessels of the rabbit eyes were clear and coherent in the projection images, and the distribution and trend of some small vessels could be observed, with the smallest distinguishable blood vessel diameter being about 10 μm. The 3D model for vessel network of the rabbit eyes was built after 3D reconstruction of CT scan images. The major arterial circle of the iris could be observed at level 4 branch structure of vessels in the fundus, and the minimum diameter of vessels that could be identified was 40 μm. Conclusions The vessels of the rabbit eyes can be clearly observed and 3D visualization of vessel network can be constructed by using XPCI technique, which would provide basis for the analysis on hemodynamics of blood vessels in the eye and reference for the clinical study of glaucoma.
ABSTRACT
Objective To measure the rabbit retinal nerve fiber layer(RNFL) thickness in vivo under different intraocular pressures (IOP) and at different time intervals after acute high IOP, and to obtain the regularity on change of RNFL thickness with acute high IOP. Methods Four groups of acute high IOP model were formed by perfusing the saline water into the anterior chamber of rabbit eyes, then RNFL thickness under different IOPs was measured by optical coherence tomography with radial scanning mode whose center was optical papilla and diameter was 6 mm. Results The absolute change values of RNFL thickness were(-27.16±14.24), (-33.33±6.74), (-48.75±5.24), (-67.29±3.89) μm under different IOPs of (4.50±0.35), (6.07±0.31), (7.74±0.26), (10.71±0.07) kPa, respectively. The linear relationship was found between the relative change of RNFL thickness and IOP. IOP could return to the normal level within two days after acute high IOP, while the RNFL thickness could be restored at the second week, and it was easier to restore if the IOP was lower than 6.65 kPa. Conclusions The acute high IOP could cause RNFL thickness to decrease significantly with the increased acute high IOP, but it will be restored after some time.
ABSTRACT
Objective To obtain pressure-volume relatioship for the rabbit eye in vivo. Method Physiological salt solution was injected with the rate of 20 μL/min through the limbus to the anterior chamber of the rabbit eye for 100 min and the intraocular pressure (IOP) was recorded. Results The relationship between IOP and injection time could be fitted to a segmented function with a characteristic point called IOPg. The ocular rigidity coefficients before and after this IOPg were (4.02±0.86) mmH2O/μL and (2.43±0.94) mmH2O/μL, respectively (1 mmH2O=9.8 Pa), showing significant difference. Conclusions IOPg existed in all curves of IOP and injection time and the ocular rigidity coefficients were dependent on the injection rate and position of IOPg. Parameters of the fit function between IOP and injection time have definite physiological significance.