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Objective To observe and compare the effects of intraocular pressure (IOP) drop on using two kinds of aqueous drainage device implantation. Methods Forty healthy New Zealand white rabbits were chosen for the experiments. According to different implant devices, they were divided into NADI (new aqueous drainage implant) group and Ahmed group respectively, with 20 rabbits in each. Results Neither group appeared shallow anterior chamber after operation. At 8th week after operation, the postoperative IOP of NADI group and Ahmed group was decreased by 19.4% and 15.7%, respectively, as compared to the preoperative IOP. Statistical comparison showed that there were significant differences in IOP between two groups within 8 weeks (P＜0.05), and the IOP of NADI group was decreased more significantly than that of Ahmed group. Conclusions The IOP in NADI group was reduced more than that in Ahmed group, and such IOP drop was maintained for a longer period in NADI group, which means that NADI has an obvious IOP drop effect and good prospect in clinical application.
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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.
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Objective To observe and compare the effects of intraocular pressure (IOP) drop when the aqueous humor was drained to limbus, ambitus and posterior segment of rabbit eye by implanting medical silicone tube. Methods Forty-five healthy New Zealand white rabbits were chosen for the experimental group, each with the medical silicone tube implanted in one eye. According to different implanting ways, the rabbits were divided into the limbus group, ambitus group and posterior segment group respectively, with 15 rabbits in each group. Results According to statistical comparison of preoperative and postoperative IOP values among the 3 groups within 4 weeks, the IOP of the posterior segment group was decreased most by 26.6%, and that of the ambitus group and limbal group was decreased by 16.2% and 1.2%, respectively. The differences between the preoperative and postoperative IOP in first, second and fourth week were statistically significant (P<0.01) for all three groups. The IOP of the posterior segment group after 4 weeks was decreased most, and there were significant differences in IOP values among three groups (P<0.01). Conclusions The greatest IOP drop occurred when the aqueous humor was drained to the posterior segment of the rabbit eye, and this result could provide some reference for the clinical surgery.
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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.
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Objective To measure the iris elastic modulus. Method Using the self designed device, the information of in vitro holistic iris deformation of rabbits were obtained with the load pressure increasing gradually from 0 Pa to 600 Pa, and the heights of such iris were computed. The corresponding model based on experimental data was established and analyzed by ANSYS finite element software, and the iris elastic modulus was computed by a reverse method. Results The elastic modulus is 6.1 kPa at 100 Pa load pressure. ConclusionsThe iris material can be considered as linear elastic model when the pressure difference between the anterior chamber and posterior chamber is low.
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<p><b>OBJECTIVE</b>To assess the clinical value of three-dimensional contrast-enhanced magnetic resonance angiography (3D-CE-MRA) in the diagnosis of mesenteric arteriosclerosis.</p><p><b>METHODS</b>3D-CE-MRA of the mesenteric arteries was performed in 21 patients with 23 healthy subjects as the control. After 3D image reconstruction and maxi intense projection, and the abnormalities of the mesenteric arteries were observed and analyzed. The diameter and number of the arterial branches were compared between the patients and the control subjects.</p><p><b>RESULTS</b>All the 21 patients suffered arteriosclerosis in the arteries other than the mesenteric arteries. On 3D-CE-MRA, mesenteric arteriosclerosis was characterized by thinning of the arterial trunk, luminal stenosis, irregular arterial margins and homo- or heterogeneous thickening of vascular walls. Multiple filling defects were found in the mesenteric artery lumens with reduced second order branches, which showed rigid lining with dashed line appearance or disappeared in some cases. The inferior mesenteric arteries were seen in only 2 patients. The diameters of superior and inferior mesenteric arteries were 3.8-/+0.32 mm and 1.20-/+0.12 mm in the patients, significantly smaller than those of in the control subjects (6.51-/+1.01 mm and 2.90-/+0.90 mm, respectively, P<0.01). The number of the mesenteric artery branch of the patients was also significantly reduced as compared with that in the control subjects (P<0.05). In som cases, the intestinal enhancement was attenuated with the intestinal contraction, dilatation and lowering of the intestinal tension.</p><p><b>CONCLUSION</b>3D-CE-MRA can clearly display mesenteric arteriosclerosis and secondary intestinal changes, and provides a useful means for the diagnosis and assisting the therapy of mesenteric arteriosclerosis.</p>