Studies have been shown that intraocular pressure (IOP) shows a seasonal variation, but amount of change differs from study to study. The variability in their results may be due to negligence of factors that can affect IOP. Due to differences in environmental conditions of China than other countries, we investigated seasonal variations in IOP of 103 healthy male Chinese of Shanghai. IOP was measured each month over the course of fourteen months with the Goldmann applanation tonometer. The average intraocular pressures in the winter months were higher than those in the spring, summer, and autumn months. The IOP difference between winter and summer months was found to be 1.4 +/- 0.7 mmHg.This study confirms that season influences IOP. As compared to other nations, effect of seasons on IOP seems to be somewhat less pronounced in Chinese. The possible mechanisms, responsible for the seasonal variation of intraocular pressure, are also postulated.
Adult ; Analysis of Variance ; Blood Pressure ; China ; Humans ; Intraocular Pressure/*physiology ; Male ; Reference Values ; *Seasons ; Tonometry, Ocular

BACKGROUNDElevated intraocular pressure (IOP) is primarily due to increased aqueous outflow resistance, but how aqueous outflow resistance is generated and regulated are still not fully understood. The aim of this study is to determine whether changes in outflow facility, outflow pattern, and morphology following acute IOP elevation were reversible when the IOP was returned to a normal level in bovine eyes using a two-color tracer technique to label outflow patterns within the same eye.

METHODSTwelve fresh enucleated bovine eyes were perfused with Dulbecco's phosphate buffer saline (PBS) containing 5.5 mmol/L glucose (DBG) at 30 mmHg first to establish the baseline outflow facility followed by a fixed volume of red fluorescent microspheres (0.5 µm, 0.002% v/v). After the red tracer being replaced with DBG in the anterior chamber, perfusion was continued at 7 mmHg with the same volume of green tracer, followed by a fixative. In two control groups, the eyes were constantly perfused at either 30 mmHg (n = 6) or 7 mmHg (n = 6) using the same methods. The outflow facility (C, µl × min × (-1)mmHg(-1)), was continuously recorded. Confocal images were taken along the inner wall (IW) of the aqueous plexus (AP) in frontal sections. The percent of the effective filtration length (PEFL, PEFL = IW length exhibiting tracer labeling/total length of IW) was measured. Sections with AP were processed and examined by light microscopy. The total length of IW and the length exhibiting separation (SL) in the juxtacanalicular connective tissue (JCT) were measured. A minimum of eight collector channel (CC) ostia per eye were analyzed for herniations.

RESULTSIn the experimental (30 - 7 mmHg) group, the outflow facility was significantly higher at 7 mmHg ((4.81 - 1.33) µl × min × (-1)mmHg(-1)) than that at 30 mmHg ((0.99 ± 0.15) µl × min × (-1)mmHg(-1), P = 0.002), corresponding to a significant increase in the PEFL (P = 0.0003). The percent of CC ostia exhibiting herniations in the experimental group ((67.40 ± 8.90) µl × min × (-1)mmHg(-1)) decreased significantly compared to that in the control at 30 mmHg ((94.44 ± 3.33) µl × min × (-1)mmHg(-1), P = 0.03), but higher than that in the control at 7 mmHg ((29.43 ± 4.60) µl × min × (-1)mmHg(-1), P = 0.01). Washout-associated separation between the IW and JCT was found by light microscopy and percent separation length (PSL, PSL = SL/total length of IW) was decreased in the control at 30 mmHg compared to that in the experimental group and control at 7 mmHg.

CONCLUSIONSThe pressure-induced morphological and hydrodynamic changes were reversible. Changes (collapse of AP, separation between the JCT and IW, and herniation into CC ostia) influence the effective filtration area that regulates outflow facility.

Animals ; Aqueous Humor ; physiology ; Cattle ; Hydrodynamics ; Intraocular Pressure ; physiology ; Microscopy, Confocal

The present study was planned to investigate the relationship between the magnitude of intraocular pressure (IOP) reduction after short-duration exercise and the intensity, duration and quantity of exercise in healthy subjects. Twenty-five healthy, sedentary male of the same age group, performed exercises at the levels of 80%, 60%, and 40% maximum heart rate (HRmax) for 15 minutes, 80% HRmax for 7.5 minutes, 60% HRmax for 10 minutes, and 40% HRmax for 30 minutes. IOP was measured with the Goldmann applanation tonometer. The IOP reduction at 5 minutes after 15 minutes of exercising at 80% HRmax, 60% HRmax, and 40% HRmax were 4.7 +/- 0.9, 3.5 +/- 0.7, and 0.9 +/- 0.4 mmHg, respectively. At five minutes, after exercising 7.5 minutes at 80% HRmax, 10 minutes at 60% HRmax, and 30 minutes at 40% HRmax, IOP reduced by 4.5 +/- 0.7, 3.3 +/- 0.9, and 2.9 +/- 1.1 mmHg, respectively. This study concludes that intensity of exercise seems responsible for the magnitude of the initial IOP decrease after short-term exercise. Furthermore, it seems that other factors such as duration of exercise or quantity of exercise, blood pressures, body mass index are not related to the amount of the initial fall in IOP.
Adult ; Blood Pressure ; Body Mass Index ; Exercise/*physiology ; Heart Rate ; Humans ; Intraocular Pressure/*physiology ; Male ; Reference Values ; Tonometry, Ocular

The objective of this study was to evaluate and validate the accuracy of the Perkins handheld applanation tonometer for measuring intraocular pressure (IOP) in horses and cattle. Both eyes of 10 adult horses and cattle were evaluated in a postmortem study. The eyes from 10 clinically normal adult horses and cattle were also examined after bilateral auriculopalpebral nerve block and topical anesthesia for an in vivo study. IOP was measured postmortem using direct manometry (measured with an aneroid manometer) and tonometry (measured with a Perkins handheld applanation tonometer). The correlation coefficients (r2 ) for the data from the postmortem manometry and Perkins tonometer study were 0.866 for horses and 0.864 for cattle. In the in vivo study, IOP in horses was 25.1 +/- 2.9 mmHg (range 19.0~30.0 mmHg) as measured by manometry and 23.4 +/- 3.2 mmHg (range 18.6~28.4 mmHg) according to tonometry. In cattle, IOP was found to be 19.7 +/- 1.2 mmHg (range 18.0~22.0 mmHg) by manometry and 18.8 +/- 1.7 mmHg (range 15.9~20.8 mmHg) by tonometry. There was a strong correlation between the IOP values obtained by direct ocular manometry and the tonometer in both horses and cattle. Our results demonstrate that the Perkins handheld tonometer could be an additional tool for accurately measuring IOP in equine and bovine eyes.
Animals ; Cattle/*physiology ; Eye/*physiopathology ; Horses/*physiology ; Intraocular Pressure/*physiology ; Linear Models ; Manometry/instrumentation/veterinary ; Tonometry, Ocular/instrumentation/*veterinary

BACKGROUNDAhmed glaucoma valves (AGV) has been used for decades, but there is no detailed report about the efficacy of AGV in Chinese glaucoma patients. This study aimed to compare the intraocular pressure (IOP) lowering efficacy and side effects of S-2 polypropylene and PF-7 silicone AGV implantation in Chinese refractory glaucoma patients.

METHODSPatients were divided into S-2 model AGV group and FP-7 model AGV group. The complete and qualified surgical success rate, change of IOP, number of anti-glaucoma medications used and postoperative complications were recorded and analyzed.

RESULTSAverage follow-up time was comparable between two groups. IOP was reduced from (37.9 ± 12.7) mmHg preoperatively to (17.3 ± 5.3) mmHg at the last follow-up in S-2 group and reduced from (39.9 ± 14.4) mmHg to (17.7 ± 4.9) mmHg in FP-7 group. Anti-glaucoma medications were reduced from 3.8 ± 0.2 to 1.5 ± 0.2 in S-2 group, and 3.5 ± 0.2 to 0.7 ± 0.2 in FP-7 groups. The cumulative success rates were comparable in two groups, which were 61.2% and 72.1% in S-2 group and FP-7 group respectively. When IOP reduction criteria was used, complete success rates were 30.6% and 51.2% for S-2 and FP-7 groups, and qualified success rates were 86.1% and 92.7% separately. In both groups, the major complication was hypotony, and the previous trabeculectomy of patients was the major risk factor for surgery failure.

CONCLUSIONSIn this short-term retrospective study, S-2 AGV is showed at least as effective as FP-7 AGV in IOP reduction, but associated with higher rate of complications. Previous trabeculectomy is a principle risk factor for AGV implantation failure. These clinical outcomes are important for converting use of the FP-7 silicon AGV in Chinese refractory glaucoma patients.

Adult ; Female ; Glaucoma ; physiopathology ; therapy ; Glaucoma Drainage Implants ; Humans ; Intraocular Pressure ; physiology ; Male ; Retrospective Studies

BACKGROUNDElevation of intraocular pressure is usually associated with primary open angle glaucoma and caused by increased outflow resistance. A two-color fluorescent tracer technique was developed to investigate the hydrodynamics of aqueous humor outflow with changing intraocular pressure within the same eye, to better understand the relationship between outflow facility and effective filtration area.

METHODSEighteen enucleated bovine eyes were first perfused at 30 mmHg with Dulbecco's phosphate-buffered saline containing 5.5 mmol/L D-glucose. After a stable baseline facility, red fluorescent microspheres (0.5 microm, 0.002% v/v) were exchanged and perfused. Eyes in the one-color control group (n = 6) were immediately perfused with fixative. In the experimental group (n = 6), eyes were perfused with green tracer after intraocular pressure reduced to 7 mmHg, while in the two-color control group (n = 6), eyes were perfused with green tracer with intraocular pressure remaining at 30 mmHg. All 12 eyes were then perfusion-fixed. Outflow facility was continuously recorded in all eyes. Confocal images were taken along the inner wall of the aqueous plexus and the percent of the effective filtration length (PEFL; length of inner wall exhibiting tracer labeling/total length of inner wall) was measured. The relationships between outflow facility and PEFL were analyzed statistically.

RESULTSNo significant differences were found in baseline facilities (microl x min(-1) x mmHg(-1)) among the three groups (the experimental group: 0.93 +/- 0.12; the two-color control group: 0.90 +/- 0.19; the one-color control group: 0.98 +/- 0.13). In the experimental group, the outflow facility was significantly higher at 7 mmHg (4.29 +/- 1.01) than that at 30 mmHg (1.90 +/- 0.67, P < 0.001), which corresponded to a significant increase in the PEFL at 7 mmHg (54.70 +/- 8.42) from that at 30 mmHg ((11.76 +/- 4.56)%, P < 0.001). The PEFL labeled by red fluorescent microspheres in the experimental group ((11.76 +/- 4.56)%) showed no significant difference from that of the one-color control group ((13.39 +/- 2.19)%, P = 0.473) or the two-color control group ((11.49 +/- 4.95)%, P = 0.930). The PEFL labeled by green fluorescent microspheres in the experimental group ((54.70 +/- 8.42)%) was significantly higher than that of the two color control group ((37.34 +/- 8.17)%, P = 0.010). A positive correlation was found between outflow facility and PEFL (r = 0.897, R(2) = 0.804) in the experimental group.

CONCLUSIONSChanges in aqueous humor outflow patterns before and after a change in intraocular pressure can be successfully distinguished within the same eye using our newly developed two-color tracer perfusion technique. The PEFL showed positive correlation with the outflow facility.

Animals ; Aqueous Humor ; physiology ; Cattle ; Intraocular Pressure ; Luminescent Proteins ; metabolism ; Microscopy, Confocal ; Microspheres ; Perfusion ; methods

The measurement of the rate of flow of aqueous humor is very important for the investigation of the physiology in the aqueous humor and maintenance of the intraocular pressure. Argon laser trabeculoplasty apears to be effective in lowering intraocular pressure with much advantage over standard filtering operation but despite the, widespread use of argon laser traheculoplasty in medically unresponsive open angle glaucoma, the exact mechanism by which it reduce outflow resistance remains unknown and so the study of the mechanism and the most suitable site are required due to the associated complication and less effectiveness during long term evaluation. We studied the changes in the rate of constant, the rate of flow for 2 weeks, intraocular pressure and C-value for 4 weeks, histopathologic changes for 36 days after argon laser trabeculoplasty in 25 rabbits(21 white and 4 black). The normal control group of 20 rabbits was also measured for intraocular pressure and C-value and the rate of constant, the rate of flow. In trabeculoplasty, we used the Britt 900 argon laser photocoagulator(pulse wave) with 50~60 burns at a setting of 700~800 mW, 0.2 seconds duration, 50 micro beam diameter in 360 degrees portion at the site between scleral spur and trabecularmeshwork. The results were as follows; 1) In control group of 20 rabbits. 1. The mean normal intraocular pressure was 18.5 +/- 2.0mmHg. 2. The mean normal C-value was 0.385 +/- 0.072 cumm/min/mmHg. 3. The mean normal rate of constant was 0.0114 +/- 0.0021min(-1). 4. The mean normal rate of flow was 3.980 +/- 0.735 micro l/min. 5. The relationship between rate of flow and C-value was high. 2) In rabbits after argon laser trabeculoplasty. 1. The white and black rabbits showed a statistically significant decrease of intraocular pressure for 4 weeks and elevation of rate of flow for 2 weeks after argon laser trabeculoplasty (p<0.001). 2. The changes of post-laser intraocular pressure was related with changes of C-value after argon laser trabeculoplasty for 4 weeks. 3. The changes of the mean IOP and C-value for post-laser 4 weeks showed no significant differences between white group and black group. 4. In histopathologic changes for 36 days, inflammtory change was not seen for post-laser period, fibrosis and edema in trabecular meshwork was more prominent at the 8th day, edema and fibrosis was regressed as normal at the post-laser 27th day.
Aqueous Humor* ; Argon* ; Burns ; Edema ; Fibrosis ; Glaucoma, Open-Angle ; Intraocular Pressure ; Physiology ; Rabbits* ; Trabecular Meshwork ; Trabeculectomy*

A randomized prospective study was performed to evaluate intraocular pressure (IOP) change after extracapsular cataract extraction (ECCE) or phacoemulsification and aspiration (PEA) with implantation of posterior chamber intraocular lens in otherwise normal cataract patients. IOP was measured preoperatively and postoperatively at up to 6 months. There was a mean fall in pressure of 1.1mmHg (5.72%) in the ECCE group (15 eyes) and of 0.6mmHg (4.16%) in the PEA group (24 eyes) after 6 months. The decrease in mean IOP was significant at 2 months in the PEA group and at 4 to 6 months in the ECCE group, but there was no statistically significant difference between the two groups during the follow-up periods (p < 0.05). The present study shows that there was some postoperative IOP reduction in both the ECCE and PEA group, but the amount of reduction was not significantly different between the two groups.
Aged ; Aged, 80 and over ; Cataract Extraction ; Female ; Follow-Up Studies ; Humans ; Intraocular Pressure/*physiology ; Lenses, Intraocular ; Male ; Middle Aged ; *Phacoemulsification ; Postoperative Period ; Prospective Studies

BACKGROUNDGlaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells (RGCs). High intraocular pressure (HIOP), the main risk factor, causes the optic nerve damage. However, the precise mechanism of HIOP-induced RGC death is not yet completely understood. This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures, explore whether laminin is associated with apoptosis under pressure, whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival.

METHODSRGC-5 cells were exposed to 0, 20, 40, and 60 mmHg in a pressurized incubator for 6, 12, and 24 h, respectively. The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blotting of cleaved caspase-3 protein. Location and expression of laminin were detected by immunofluorescence. The expression of β1-integrin, phosphorylation of focal adhesion kinase (FAK) and protein kinase B (PKB, or AKT) were investigated with real-time polymerase chain reaction and Western blotting analysis.

RESULTSElevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells. Pressure with 40 mmHg for 24 h induced a maximum apoptosis. Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h. After pretreating with laminin, RGC-5 cells survived from elevated pressure. Furthermore, β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group.

CONCLUSIONSThe data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure. Laminin can protect RGC-5 cells against high pressure via β1-integrin/FAK/AKT signaling pathway. These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure, and laminin or activating β1-integrin/FAK/AKT pathway might be potential treatments to prevent RGC loss in glaucomatous optic neuropathy.

Apoptosis ; Cells, Cultured ; Focal Adhesion Protein-Tyrosine Kinases ; physiology ; Humans ; Hydrostatic Pressure ; Integrin beta1 ; physiology ; Intraocular Pressure ; Laminin ; physiology ; Proto-Oncogene Proteins c-akt ; physiology ; Retinal Ganglion Cells ; physiology ; Up-Regulation

The purpose of this study was to report developmental glaucoma and pseudopapilledema in a patient with Proteus syndrome. We defined the presence of developmental glaucoma, right pseudopapilledema and myopia in a 4.5-year-old patient with Proteus syndrome. Marked right hemihypertrophy, lipoma, macrodactyly, and asymmetry of the limbs were observed on systemic examination. A cavernoma was also detected in magnetic resonance imaging of the brain. The patient underwent bilateral goniotomy surgery due to glaucoma. The surgical outcomes were satisfactory in both eyes. In conclusions developmental glaucoma and pseudopapilledema might be associated with Proteus syndrome.
Child, Preschool ; Disease Progression ; Glaucoma/diagnosis/*etiology/physiopathology ; Humans ; Intraocular Pressure/*physiology ; Magnetic Resonance Imaging/*methods ; Male ; Proteus Syndrome/*complications