In this paper,the changes of activities of enzymes relating toenergy metabolism in rabbit's retina during acute ocular hypertension were observed.The activities of succinate dehydrogenase and adenosine triphosphatase were foud to be reduced,while the activities of the lactatic dehydrognease and glucose-6-phosphatase increased.The results reveal the disturbance of metabolism of energy in retina undergone acute ocular hypertension,and suggest that this might be the underlying factors relating to the defects of the functions and structures of the retina. （Chin J Ocul Fundus Dis,1993,9:141-144）
Objective To investigate the occurrence, progress and conversion of hypotony in anterior proliferative vitreoretinopathy (aPVR), and to provide knowledge about how to prevent and treat it． Methods Animal models of chronic hypotony by aPVR were made with cultured ho mologous dermal fibroblasts on pigmented rabbits．The intraocular pressure (IOP) and ultrasound biomicroscopy(UBM) examination were taken preoperatively and on days 7,14, 28 and 56 postoperatively．Rabbits were killed on days 14, 28 or 56 postoperatively, prepared for histology and ultrastructure examination． Results The average IOP of experimental group was lower than that of control group on days 7,14,28 and 56 significantly (Plt;0．01)．UBM demonstrated that trip like echo emerged in front of ciliary body four weeks postoperatively, and tractional retinal detachment was found four weeks and eight weeks postoperatively in experimental group． Microscopic examination showed atrophy orabsence of the non-pigmented ciliary epithelium on days 28 and 56 postoperatively in experimental group．Electronic microscopy showed that the amount of mitochondrions decreased and there were many vacuoles in the non-pigmented ciliary epithelium in experimental group four and eight weeks postoperatively． Conclusions Atrophic change of the non-pigmented epithelium due to dragging effect of the ciliary body from the epiciliary membrane in aPVR might be the main cause of hypotony． (Chin J Ocul Fundus Dis, 2001,17:216-220)
Objective To investigate the effect of proanthocyanidins (PC) on retina of rats with acute ocular hypertension. Methods The SpraqueDawley (SD) rats were randomly divided into the normal group, the model group and PC high or lowdosage group. The PC high or low dose group received 300mg/kg.d or 100mg/kg.d of PC in suspension solution for 5 days respectively. The normal group and the model group fed with distilled water for 5 days. Then acute ocular hypertension was induced in the model group and all PC groups, and after 48h of ocular hypertension the eyeballs were analyzed by electron microscope and UV spectrophotometer to measure the levels of superoxide dismutase(SOD), malonaldehyde (MDA), nitrogen monoxidum (NO), glutamic acid (Glu) and calcium ion(Ca2+). Results PC could raise the activity of SOD and reduced the levels of MDA,NO,Glu and Ca2+ in retina tissue. Electron microscope examination revealed that PC reduced retinal edema and ganglion cell apoptosis. PC also enhanced the SOD activity and suppressed the levels of MDA, NO, Glu and Ca2+. Conclusions PC can protect retina from acute ocular hypertension. The main mechanism might relate to anti-free radical oxidation, antagonizing calcium overloading, reducing toxicity of NO and Glu on the retina.
The occurrence of high intraocular pressure (IOP) after vitrectomy for diabetic retinopathy (DR) is related to many factors, including the type and stage of DR, macular detachment, surgical methods, and the type of ocular tamponade. Early high IOP occurred mainly due to laser photocoagulation, inflammatory response, improper ocular tamponade, residual viscoelastic agents and ciliary body dysfunction. In addition to the above reasons, early-middle stage high IOP is also related to tamponade gas expansion peak, encircling scleral buckle and hyphema. The major reason for middle-stage high IOP is hyphema and silicon oil in anterior chamber. The reasons for late-stage high IOP are glaucoma, silicone oil emulsification, long-term use of glucocorticoid, and iris incision closure. Most high IOP can be controlled by proper treatment such as stopping use of glucocorticoid, anti-glaucoma eye drops and surgeries. But there are still a small number of patients with unexplained refractory high IOP, the mechanism need to be further explored.
Due to lack of the practical technique to measure the biomechanical properties of the ocular cornea in vivo, clinical ophthalmologists have some difficulties in understanding the deformation mechanism of the cornea under the action of physiological intraocular pressures. Using Young's theory analysis of the corneal deformation during applanation tonometry, the relation between the elasticity moduli of the cornea and the applanated corneal area and the measured and true intraocular pressures can be obtained. A new applanation technique has been developed for measuring the biomechanical properties of the ocular cornea tissue in vivo, which can simultaneously acquire the data of the applanation area and displacement of the corneal deformation as well as the exerted applanation force on the cornea. Experimental results on a rabbit's eyeball demonstrated that the present technique could be used to measure the elasticity moduli and creep properties of the ocular cornea nondestructively in vivo.
Objective To investigate the factors associated with short-term elevation of intraocular pressure after ranibizumab intravitreal injection. Methods 292 eyes of 292 patients who were diagnosed retinopathy and suitable to receive ranibizumab intravitreal injection were enrolled in this prospective clinical study. There were 157 males and 135 females. 193 patients diagnosed with age-related macular degeneration and 99 other retinopathy patients. Mean age of patients was 62.75±13.74 years. All subjects underwent systemic and comprehensive ophthalmology examinations. The mean BCVA was 0.68±0.47 logMAR. Mean basal intraocular pressure was 18.1 mmHg (1 mmHg=0.133 kPa). All patients received intravitreal injection with 0.05 ml of ranibizumab (0.5 mg). The intraocular pressure were measured by non-contact tonometer at 10, 30, 120 minutes and 1 day after injection in a sitting position. The patients were grouped by the changes of intraocular pressure 10 minutes after injection. The elevation was more than 10 mmHg as elevation group and less than 10 mmHg as stable group. Analyze the possible related factors with elevation of intraocular pressure after ranibizumab intravitreal injection by comparing the different datum of two groups. Results The mean intraocular pressure were 23.8, 20.5, 19.9 and 17.4 mmHg at 10, 30, 120 minutes and 1 day after injection. The significant elevation level were 5.8, 2.4, 1.8, −0.7 mmHg compared with basal intraocular pressure. Among 292 eyes, intraocular pressure elevation in 68 eyes and stabled in 224 eyes. The age (Z=−0.732), gender (χ2=1.929), right or left eye (χ2=2.910), BCVA (Z=−0.039), diseases (χ2=2.088) were no significant difference between two groups (P＞0.05). The injection number (Z=−2.413, P=0.001), basal intraocular pressure (Z=−3.405, P=0.016) and elevations after injection (Z=−11.501, −8.366, −5.135, −3.568; P＜0.01) were significantly different comparing two groups (P＜0.05). By logistic regression analysis, basal intraocular pressure was positively correlated with the elevation of intraocular pressure 10 minutes after injection (B=−0.844, OR=0.43, 95%CI 0.24−0.76, P=0.004). Patients with higher basal intraocular pressure may occur intraocular pressure elevation after ranibizumab intravitreal injection much probably. Conclusions The factors associated with short-term elevation of intraocular pressure after ranibizumab intravitreal injection were basal intraocular pressure. The higher basal intraocular pressure, the higher risk to gain elevation of intraocular pressure after injection.
Intraocular pressure detection has a great significance for understanding the status of eye health, prevention and treatment of diseases such as glaucoma. Traditional intraocular pressure detection needs to be held in the hospital. It is not only time-consuming to doctors and patients, but also difficult to achieve 24 hour-continuous detection. Microminiaturization of the intraocular pressure sensor and wearing it as a contact lens, which is convenient, comfortable and noninvasive, can solve this problem because the soft contact lens with an embedded micro fabricated strain gauge allows the measurement of changes in corneal curvature to correlate to variations of intraocular pressure. We fabricated a strain gauge using micro-electron mechanical systems, and integrated with the contact lens made of polydimethylsiloxane (PDMS) using injection molding. The experimental results showed that the sensitivity was 100.7 μV/μm. When attached to the corneal surface, the average sensitivity of sensor response of intraocular pressure can be 125.8 μV/mm Hg under the ideal condition.