Decline In Intraocular Pressure Research Articles

Intraocular pressure across the lifespan of Tg-MYOCY437H mice

Transgenic C57BL/6 mice expressing human myocilinY437 (Tg-MYOCY437H) are a well-established model for primary open-angle glaucoma (POAG). While the reduced trabecular meshwork (TM) cellularity due to severe endoplasmic reticulum (ER) stress has been characterized as the etiology of this model, there is a limited understanding of how glaucomatous phenotypes evolve over the lifespan of Tg-MyocY437H mice. In this study, we compiled the model's intraocular pressure (IOP) data recorded in our laboratory from 2017 to 2023 and selected representative eyes to measure the outflow facility (Cr), a critical parameter indicating the condition of the conventional TM pathway. We found that Tg-MYOCY437H mice aged 4−12 months exhibited significantly higher IOPs than age-matched C57BL/6 mice. Notably, a decline in IOP was observed in Tg-MYOCY437H mice at 17−24 months of age, a phenomenon not attributable to the gene dosage of mutant myocilin. Measurements of the Cr of Tg-MYOCY437H mice indicated that the age-related IOP reduction was not a result of ongoing TM damage. Instead, Hematoxylin and Eosin staining, immunohistochemistry analysis, and transmission electron microscopic examination revealed that this reduction might be induced by degenerations of the non-pigmented epithelium in the ciliary body of aged Tg-MYOCY437H mice. Overall, our findings provide a comprehensive profile of mutant myocilin-induced ocular changes over the Tg-MYOCY437H mouse lifespan and suggest a specific temporal window of elevated IOP that may be ideal for experimental purposes.

Ophthalmic Bimatoprost-Loaded Niosomal In Situ Gel: Preparation, Optimization, and In Vivo Pharmacodynamics Study.

This study aimed at formulating the antiglaucoma agent, Bimatoprost (BMT), into niosomal in situ gel (BMT-ISG) for ocular delivery. Niosomes containing cholesterol/span 60 entrapping BMT were fabricated using a thin-film hydration method. The fabricated niosomes were optimized and characterized for entrapment efficiency (%EE) and size. The optimized BMT-loaded niosomal formulation prepared at a cholesterol/span 60 ratio of 1:2 exhibited the highest entrapment (81.2 ± 1.2%) and a small particle size (167.3 ± 9.1 nm), and they were selected for incorporation into in situ gelling systems (BMT-ISGs) based on Pluronic F127/Pluronic F68. Finally, the in vivo efficiency of the BMT-ISG formulation, in terms of lowering the intraocular pressure (IOP) in normotensive male albino rabbits following ocular administration, was assessed and compared to that of BMT ophthalmic solution. All the formulated BMT-ISGs showed sol-gel transition temperatures ranging from 28.1 °C to 40.5 ± 1.6 °C. In addition, the BMT-ISG formulation sustained in vitro BMT release for up to 24 h. Interestingly, in vivo experiments depicted that topical ocular administration of optimized BMT-ISG formulation elicited a significant decline in IOP, with maximum mean decreases in IOP of 9.7 ± 0.6 mm Hg, compared to BMT aqueous solution (5.8 ± 0.6 mm Hg). Most importantly, no signs of irritation to the rabbit's eye were observed following topical ocular administration of the optimized BMT-ISG formulation. Collectively, our results suggested that niosomal in situ gels might be a feasible delivery vehicle for topical ocular administration of anti-glaucoma agents, particularly those with poor ocular bioavailability.

Changes to Outflow Structures After Pilocarpine in Primary Open Angle Glaucoma Compared With Healthy Individuals Using Optical Coherence Tomography.

Lower response of aqueous outflow pathway structures after pilocarpine could be observed in primary open angle glaucoma (POAG) patients, which is likely to be helpful for understanding intraocular pressure (IOP) evaluation in glaucoma. To evaluate the morphologic changes in the trabecular meshwork (TM), Schlemm canal (SC), scleral spur (SS), and ciliary muscle after miosis in patients with POAG and healthy individuals. A total of 30 patients with POAG and 26 healthy controls were recruited. All participants underwent complete ophthalmologic examinations, including IOP and swept-source optical coherence tomography (OCT), before and 1 hour after the local administration of pilocarpine (2%). OCT measurements included TM thickness and width, SC diameter and area, SS length, ciliary muscle thickness, and ciliary muscle angle (CMA). Pilocarpine administration induced a decline in IOP (15.6±2.3-14.6±2.2mmHg), decrease in nasal SS length (196.31±47.75-171.52±33.93μm), decrease in TM thickness (90.18±16.43-83.02±13.74μm), and increase in SC diameter (134.84±32.28-162.08±48.67μm) and SC area (3851.37±1455.07-4801.39±1762.37μm 2 ) among healthy controls. In contrast, no significant changes in IOP and OCT measurements were found in patients with POAG. At baseline, CMA was independently correlated with IOP in normal eyes. After miosis, the change in TM thickness was independently correlated with changes in IOP in normal eyes; in eyes with POAG, changes in SS length and CMA were independently associated with changes in IOP. Topical pilocarpine-induced morphologic changes to outflow pathway structures in healthy individuals without significant changes in POAG. The lower response observed in patients with glaucoma may be relevant to understanding IOP changes.

Age-Related Changes in Intraocular Pressure: Japan Ningen Dock Study.

The analysis of intraocular pressure by age using a mega database showed a consistent age-related intraocular pressure decrease. To clarify the association between age and intraocular pressure (IOP), the IOP value by age was assessed using a large IOP database. This cross-sectional study was conducted among 103 health checkup institutions registered to the Japan Society of Ningen Dock, and included participants who underwent annual health checkups between April 2014 and March 2015. The inclusion criteria were as follows: complete data for IOP in eyes, body mass index, waist circumference, blood pressure, hemoglobin A1c, and a self-administered health questionnaire. A total of 655,818 participants were enrolled. The mean age was 51.5±10.5 years (range, 20-96y), and 40.1% were women. IOP was measured using a noncontact tonometer. Multiple linear regression analysis was conducted to explore factors associated with IOP, including age, and analyses stratified by age group: <40, 40-69, and ≥70 years. A consistent negative association between IOP and age [β=-0.353 (95% confidence interval: -0.360--0.346)] was observed. In the age groups of <40 and ≥70 years, the age-related IOP decline was more pronounced [β=-0.502 (95% CI: -0.566 to -0.439); β=-0.674 (95% CI: -0.753 to -0.595)], with it being 14.21±2.95 and 11.18±2.52mm Hg in the 20-24 and 90-96 year age groups, respectively. The middle-aged (aged 40-69y) population showed gradual decline [β=-0.313 (95% CI: -0.323 to -0.303)]. Age was strongly and negatively associated with IOP. The magnitude of IOP decline across lifespans was ∼3mmHg. Age-related decreases in IOP were nonlinear and phasic.

Intraocular Pressure Fluctuation during Aerobic Exercise at Different Exercise Intensities.

Few studies have examined the effects of different aerobic-exercise intensities on intraocular-pressure (IOP) changes. This may be important for eye diseases that are impacted by IOP or its fluctuation, including glaucoma, and diabetes that is complicated by diabetic retinopathy. We investigated the effects of low-, moderate-, and high-intensity exercise on IOP in healthy subjects. A submaximal cardiopulmonary exercise test was performed in 18 healthy male subjects, and the maximal oxygen uptake was calculated. The subjects then exercised for 20 min at 30%, 50%, and 70% ·VO2 of maximal oxygen uptake, and their IOP was measured at rest and every 5 min during exercise. Oxygen uptake was monitored using an expiratory gas analyzer during exercise to maintain accurate exercise intensity and adjust exercise load. Oxygen uptake during exercise was significantly higher at all intensities from 5 to 20 min than at rest. IOP was significantly lower at 70% exercise intensity from 5 to 20 min than at rest. A negative correlation existed between IOP and ·VO2. IOP remained unchanged during low- and moderate-intensity exercise but significantly declined during high-intensity exercise compared with that at rest. Although various factors, such as β-blockers, are involved in IOP decline at rest, a different mechanism is involved in IOP decline during exercise.

Post-operative Reduction in Intraocular Pressure after Small Incision Surgery

Introduction: This study aims to compare pre-operative and post-operative intraocular pressure (IOP) after small incision cataract surgery (SICS). Materials and Methods: A total of 120 eyes of as many patients above the age of 40 years were operated for cataract through SICS. IOP was recorded preoperatively and postoperatively on 1 week, 2 weeks, 1 month, and 3 months with Goldmann applanation tonometer. The above data were statistically analyzed using paired “t-test.” Results: There was a statistically significant decrease in IOP after SICS as compared to mean pre-operative IOP. IOP decline started at 1 week, decreasing further at 2 weeks, 1 month, and 3 months, respectively. Conclusion: IOP starts to decrease significantly after SICS at 1 week and keeps on decreasing till 3 months.

Seasonal Fluctuation in Intraocular Pressure and Retinal Nerve Fiber Layer Thinning in Primary Open-Angle Glaucoma

To detect seasonal fluctuations in intraocular pressure (IOP) in healthy eyes and eyes with primary open-angle glaucoma (POAG) and to evaluate whether these seasonal fluctuations affect retinal nerve fiber layer (RNFL) thinning in eyes with POAG. Observational, retrospective cohort study. Healthy population who underwent a comprehensive health check-up and patients with POAG using only topical medications were enrolled. Kaplan-Meier survival analysis was used to compare the cumulative incidence probabilities of RNFL thinning between different seasonal IOP fluctuation groups. A Cox proportional hazards model, with adjustments for potential confounding factors, was used to evaluate the association between seasonal fluctuations in IOP and RNFL thinning. Intraocular pressure fluctuation rate calculated from winter and summer IOPs and RNFL thinning as determined by event-based analysis with high-definition OCT. A total of 12 686 healthy eyes and 179 eyes of 179 POAG patients showed a significantly higher IOP in winter than in summer (healthy, 13.2 ± 3.0 mmHg vs. 12.5 ± 2.9 mmHg [P < 0.001]; POAG, 13.1 ± 2.7 mmHg vs. 11.8 ± 2.3 mmHg [P < 0.001]). In POAG patients, the mean age at initial OCT and follow-up duration were 55.1± 11.7 years and 98.4 ± 26.4 months, respectively. The mean deviation (MD) at first visit, MD slope, and RNFL thinning rate were -2.2 ± 3.4 dB, -0.07 ± 0.44 dB/year, and -0.44 ± 0.88 μm/year, respectively. During the study period, 85 eyes (47.5%) showed RNFL thinning progression. Kaplan-Meier analysis showed that a high seasonal IOP fluctuation rate significantly suppressed RNFL thinning (P < 0.05, log-rank test). After adjusting for confounders in the Cox analysis, the seasonal IOP fluctuation rate still showed a significantly negative association with RNFL thinning (hazard ratio, 0.98; 95% confidence interval, 0.96-0.99; P= 0.005). Winter IOP was higher than summer IOP in both healthy and POAG eyes. The temporary IOP decline in summer, rather than a constant IOP throughout the year, may prevent glaucoma progression.

Does Bariatric Surgery Affect Intraocular Pressure?

The effect of body mass index (BMI) reduction following bariatric surgery on intraocular pressure (IOP) is not well established. We evaluated association between BMI reduction and IOP measurements and other ocular and metabolic parameters 1year after bariatric surgery. A retrospective study with over 1-year follow-up on patients who underwent weight reduction bariatric surgery between January 2016 and December 2016 at Wolfson Medical Center, Israel. Patient data was extracted from outpatient's bariatric and ocular clinic records. Metabolic, ocular, and clinical parameters were assessed including BMI changes, IOP, central corneal and retinal nerve fiber layer thickness, optical coherence tomography, and biometry results. Of 22 bariatric surgery patients, 15 underwent laparoscopic sleeve gastrectomy (LSG) and 7 laparoscopic mini gastric bypass (MGB). All were followed up for over 1year after surgery. Average BMI decreased from 41.9 ± 7.3 to 25.5 ± 5.7kg/m2 at 1-year follow-up (p < 0.001). Mean IOP decreased significantly by 21% after 1year (p < 0.001). Decrease in IOP 1year after surgery was correlated with decrease in IOP at 3-month follow-up (r = 0.677, p = 0.001), preoperative IOP (r = 0.837, p < 0.001), and corneal thickness (r = 0.589, p = 0.006), with no correlation between reduction in IOP and baseline weight, BMI, or the reduction in either (p > 0.05). Central corneal thickness and retinal nerve fiber layer thickness were also significantly decreased (p = 0.038) and (p = 0.018), respectively. BMI reduction achieved by bariatric surgery was associated with significant and continued decline in IOP beyond 1year after surgery. Clinical implications highlight the importance of considering bariatric surgery in patients with ocular hypertension.

Effect of Chloral Hydrate Sedation on Intraocular Pressure in a Pediatric Population

To determine the effect of oral chloral hydrate (CH) sedation on intraocular pressure (IOP) in an outpatient pediatric population. Prospective, noncomparative case series. Children aged 1month to 5 years undergoing CH sedation for ocular imaging/evaluation at a tertiary eye hospital were included. IOP was measured using an Icare tonometer prior to sedation (in some, not all), at 25minutes after sedation, and then every 10minutes until sedation completion. Change in IOP over time was assessed using mixed model linear regression to account for correlation of IOP readings. A total of 112 children were enrolled, 50.9% were female, and mean age was 2.1 (standard deviation [SD]: 1.3) years. Of the total, 83 (74.1%) participants had IOP measurement attempted prior to sedation, with 64 having presedation IOP completed. Among those completing presedation IOP, 46.9% were asleep/calm, and the rest (53.1%) were slightly/more distressed (IOP did not differ by level of agitation). Those with and without presedation IOP available had similar demographics and health status (P > .05). Heart rate, respiratory rate, and oxygen saturation all declined after sedation (P < .001). The mean dose of CH administered was 80.9 (SD: 13.2) mg/kg, and sedation was deemed "adequate" in 97.3% after a single dose. Mean IOP among those with presedation IOP was 19.5mm Hg and, although not significant, declined to 18.7mm Hg at 25minutes (P= .12). There was no trend toward further decline in IOP over time (P > .05). CH sedation for outpatient pediatric ophthalmic procedures as administered in this prospective assessment had no impact on IOP.

Changes in choroidal thickness following trabeculectomy and its correlation with the decline in intraocular pressure.

Evaluate whether there are significant changes in choroidal thickness following trabeculectomy, and how they relate do the decline in intraocular pressure. This was a prospective evaluation of 28 eyes who underwent Moorfields modified trabeculectomy. The choroidal thickness was measured via OCT with enhanced depth imaging, before surgery and 1day, 1week and 1month after surgery. Measurements were taken at the fovea, 1000µm temporal to the fovea and 1000µm nasal to the fovea. The relationship between choroidal thickness and intraocular pressure was statistically evaluated. The mean intraocular pressure before surgery was 25.07 ± 4.64mmHg; 8.57 ± 3.62mmHg after 1day; 10.36 ± 4.39mmHg after 1week and 13.71 ± 5.13mmHg after 1month. Mean choroidal thickness increased after trabeculectomy with maximal values at 1week. The largest increase was found at the fovea, with an average before surgery of 253.54 ± 62.01µm; 286.75 ± 64.20µm at 1day, 286.36 ± 63.14µm at 1week and 271.00 ± 60.31µm at 1month. Increase in choroidal thickness was significant 1day and 1week after surgery in the foveal (p = 0.012, p = 0.007) and temporal (p = 0.040, p = 0.000) locations and 1week postoperatively on the nasal location (p = 0.016). None of them were significant at 1month after surgery. Preoperative IOP and choroidal thickness were correlated at all macular locations (ρ = 0.449-0.525, p = 0.004-0.016) yet no correlation was found between increase in choroidal thickness and decline in intraocular pressure in the postoperative period. Choroidal thickness appears to increase temporarily after trabeculectomy and these changes were not correlated with the decline in intraocular pressure. Further research is required to fully understand this phenomenon.

Positive correlation between blood reflux in Schlemm's canal and the decrease of intraocular pressure after selective laser trabeculoplasty in primary open-angle glaucoma.

The aim of the present study was to investigate the association between blood reflux in Schlemm's canal (SC) and the decrease of intraocular pressure (IOP) after selective laser trabeculoplasty (SLT) in primary open-angle glaucoma (POAG). To verify this, 35 eyes from 25 POAG patients were enrolled. All eyes underwent 360° whole-circle gonioscopy via a three-mirror lens, prior to undergoing 360° SLT. The four quadrants of the examined eye were individually compressed by the lens, and the presence of blood reflux in SC after removal of the pressure was recorded. Eyes with no blood reflux in any quadrant were assigned to the negative group, while the others were assigned to the positive group. Patients were evaluated at baseline, at 1 and 2 weeks, and at 1, 3 and 6 months after SLT. The results indicated that in the reflux-positive (21 eyes) and -negative (14 eyes) group, a significant IOP decrease was seen at 1 and 2 weeks, and at 1 and 3 months after SLT as compared with that pre-SLT IOP (P<0.01). In the negative group, the IOP at 6 months after SLT was not significantly different (P>0.05), while the positive group still exhibited a significant decrease in IOP compared with that at baseline (P<0.01). The positive group also presented with a greater decline in IOP at 1, 3 and 6 months compared with that in the negative group (P<0.05). A positive correlation between the number of quadrants with blood reflux in SC and the percentage decrease in IOP after SLT was identified in the positive group (P<0.05). In conclusion, blood reflux in SC was positively correlated with the decrease in IOP after SLT in POAG (Trialapproval number, K-2014-013).

Continuous Intraocular Pressure Monitoring During Nocturnal Sleep in Patients With Obstructive Sleep Apnea Syndrome.

To evaluate intraocular pressure (IOP) changes during nocturnal sleep in patients with obstructive sleep apnea syndrome (OSAS) using a contact lens sensor (CLS). This was a prospective cohort study. Seven OSAS patients who had no ocular diseases except mild cataract were enrolled. Each subject underwent CLS-based continuous IOP monitoring on one eye simultaneously with overnight polysomnography. We classified the nocturnal IOP records into nonapnea IOP and apnea IOP, according to the duration of apnea events on polysomnography within each IOP measurement time of 30 seconds every 5 minutes. Differences between IOP levels during nonapnea and apnea phases were statistically analyzed. The mean apnea-hypopnea index, the total number of these events per hour of sleep, was 44.2 ± 21.0, indicating the participants' severity of OSAS as moderate to severe. The mean range of IOP fluctuations during nocturnal sleep was 262.3 ± 59.5 mV eq. All patients showed lower mean IOP levels during apnea events than during nonapnea phases, with statistically significant differences detected in four of the seven patients. On average, in all seven eyes, IOP values significantly decreased by 23.1 ± 16.4 mV eq in association with apnea events. Obstructive apnea led to an immediate IOP decline during nocturnal sleep in patients with OSAS. Attention should be paid to IOP-independent etiology, such as episodic hypoxia, potentially linking OSAS and glaucoma.

Indications and postoperative treatment for Ex-PRESS(®) insertion in Japanese patients with glaucoma: comparison with standard trabeculectomy.

BackgroundWe investigated indications and early postoperative treatment for Ex-PRESS® insertion for glaucoma by comparing postoperative outcomes with those for standard trabeculectomy.MethodsEx-PRESS insertion was performed in 21 eyes and standard trabeculectomy (TLE) in 22 eyes. Mean intraocular pressure (IOP) in the 6 months after surgery, success rate for postoperative IOP decline, postoperative complications, postoperative treatment, filtering blebs, and indications were then retrospectively investigated.ResultsMean postoperative IOP did not differ significantly between the groups at any observation time for 6 months after surgery. Further, it did not differ between either the groups of patients with primary open-angle glaucoma (POAG) and neovascular glaucoma (NTG), or the patients with primary open-angle glaucoma and NTG in the Ex-PRESS group. Comparison of success rates in reduction of postoperative IOP between the groups under the following four survival conditions showed no significant differences: postoperative IOP <30% of the preoperative IOP, complete success (no additional ophthalmic solution), and qualified success (ophthalmic solution required); 5 mmHg ≤ postoperative IOP ≤21 mmHg, complete success (no additional ophthalmic solution), and qualified success (ophthalmic solution required). With regard to postoperative complications and postoperative treatment, the incidence of hyphema was significantly lower in the Ex-PRESS group, but no other significant intergroup differences were seen. The height of the filtering bleb was lower in the Ex-PRESS group.ConclusionPostoperative outcomes in the Ex-PRESS and TLE groups were comparable. The incidence of hyphema was significantly lower in the Ex-PRESS group. Ex-PRESS insertion appears to be useful in patients with NTG and in those prone to postoperative bleeding. There were no significant intergroup differences in postoperative treatment. Assessment of outcome after Ex-PRESS insertion was difficult in some patients. Postoperative treatment should be developed to suit the specific requirements of Ex-PRESS insertion.

Intraocular pressure modulation by neuropeptides ‐ the effect of vasopressin

AbstractElevated intraocular pressure (IOP) is a major risk factor for glaucoma. Currently, the primary strategy to slow down glaucoma progression is IOP reduction. Numerous studies investigated the IOP lowering effects of neuropeptides, but the complex physiological mechanisms involved are difficult to interpret. Therefore, we investigated the effect of arginine‐vasopressin (AVP) on IOP in a multiparameter approach. In a rabbit model the effect of i.v.‐applied AVP on IOP, ciliary blood flow (CilBF) and aqueous flow (AqF) was measured simultaneously by manometry, laser‐Doppler flowmetry and fluorophotometry. AVP caused a dose‐dependent decrease of IOP, CilBF and AqF. Based on the Goldmann equation the decrease of AqF at 0.08 ng/kg/min AVP (low dose) accounted for 77.1% of the IOP reduction (9.56±2.35%), while AqF at 1.33 ng/kg/min AVP (high dose) accounted for 28.4% of the IOP decline (41.02±3.19%). The results indicate that AqF reduction by low dose AVP is mainly caused by inhibition of ciliary epithelium secretion. At high dose AVP AqF reduction is caused by decreased CilBF or more likely by a combination of CilBF decline and secretory inhibition. This conclusion is only possible with the multiparameter measurement approach presented.

The effects of intravenous romifidine on intraocular pressure in clinically normal horses and horses with incidental ophthalmic findings.

Original study. To evaluate the effect of sedation with romifidine hydrochloride 1% (Sedivet: Boehringer-Ingelheim) on intraocular pressure (IOP) in the normal horse and horses with incidental ophthalmic findings as measured by applanation tonometry. Nineteen clinically normal horses (13 geldings, six mares) and eight horses (three geldings, five mares) with incidental ophthalmic findings were included in this study. All horses underwent complete ophthalmic examination with pharmacologic mydriasis a minimum of 2 weeks prior to IOP evaluation. Baseline intraocular pressure values were obtained following auriculopalpebral nerve block and topical anesthetic. Immediately thereafter, romifidine was administered intravenously (75 µg/kg) and the IOP recorded at 5, 15, 30, 45 and 60 min postsedation in both eyes. Five successive readings were obtained at each time point, the low and high value discarded, and three remaining readings averaged for a mean. The changes with time were consistent between eyes and OD and OS results were pooled. The mean IOP at baseline was 26.35 ± 5.57 mmHg. Mean IOP values were significantly lower than baseline at 5 (P < 0.0001), 15 (P < 0.0001), 30 (P = 0.0003), 45 (P < 0.0001) and 60 (P = 0.0005) minutes. The largest change from baseline (16.7%) was noted at t = 15 min. Administration of romifidine significantly decreased the IOP from baseline at all time points measured. The greatest decline in IOP was noted at 15 min postsedation. Results are consistent with other studies noting a decline in IOP with administration of α-2 agonists.

A Three-Dimensional Collagen Gel Contraction Monitoring System that Uses A Porcine Trabecular Meshwork for Screening of Anti-Intraocular Pressure Agents

Trabecular Meshwork (TM) contractile state is thought to affect aqueous humor outflow and Intraocular Pressure (IOP). It has been suggested that TM relaxation may increase conventional outflow by increasing tissue porosity and lead to decline in IOP, therefore, it could be a therapeutic target for glaucoma. Accordingly, we investigated the effects of various agents on the contractility of cultured Porcine Trabecular Meshwork (pTM) cells using a three-dimensional (3-D) collagen gel assay, in order to develop a screening method for identifying novel anti-IOP agents. We identified pTM cells, obtained from porcine eyeballs, by cell shape and expression of Low Density Lipoprotein (LDL) receptors. The pTM cells, when embedded in collagen gels, showed contractile activity dependent on concentration of Fetal Bovine Serum (FBS). Various kinase inhibitors, especially inhibitors of cell cyclin-dependent kinase (rescovitine), rho and Ca2+-dependent protein kinase (Y-27632), tyrosine kinase (tyrphostin AG879), phosphatidylinositol 3-kinase (bisindolylmaleimide I, BIM I), and Ca2+/calmodulin kinase (chelerythrine), strongly inhibited collagen gel contraction. This contraction was also inhibited by ethacrynic acid, by inhibitors of Na+, K+-ATPase (ouabain), Ca2+- ATPase (thapsigargin), and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, by a non-selective phosphodiesterase inhibitor (papaverine), and by adenosine A2 (metrifudil), and cannabinoid receptor (CP-55940) agonists. In addition, BIM I, simvastatin, BQ-123, and CP-55940 demonstrated partial cytotoxicity. The inhibitory activities of chelerythrine and thapsigargin were also attributed to cytotoxicity. These findings indicate that this in vitro 3-D collagen gel contraction monitoring system could be used as a rapid and sensitive screening method for identifying novel agents that induce pTM cell relaxation and could simultaneously detect both main and side effects.

Changes in intraocular pressure during strabismus surgery

Objective: To determine whether the alterations in intraocular pressure (IOP) after cutting off a lateral rectus muscle during exotropia surgery could reflect the degree of muscle contracture. Design: Prospective study. Participants: Sixty eyes of 31 patients that had undergone lateral rectus recession surgery for correction of exotropia. Methods: IOP was measured usingaTono-pen XL before and after detaching lateral rectus muscles during the surgery. The changes in IOP were measured and their correlations with age, duration of disease, intermittency of exotropia, amount of exodeviation, laterality of the deviated eye, and tendon width of the muscle operated on were analyzed. Results: The mean baseline IOP was 16.3 (SD2.2) mm Hgwhen measured 5 minutes after tracheal intubation and showed a significant decline to 13.5 (SD 2.8) mm Hgwhen measured immediately before detachment of a muscle. However, the IOP decline over this period of preparation for muscle detachment was not correlated with any clinical variable tested. The mean IOP also showed a significant reduction, to 10.8 (SD 2.3) mm Hg, immediately after the muscles were cutoff the globe. The peridetachment IOP reduction was positively correlated with constant exodeviation ( p < 0.001), whereas there was no significant correlation with age, duration of exotropia, or tendon width. Conclusions: The changes in IOP seen after detaching an extraocular muscle during strabismus surgery may serve as a surrogate parameter to reflect the muscle contracture.

The effects of midazolam on intraocular pressure in children during examination under sedation

BackgroundTo obtain reliable and accurate measurements of the intraocular pressure (IOP) in children often requires sedation or anaesthesia. Therefore, we investigated the effects of oral midazolam on IOP in children.MethodsIn...

Evaluation of anterior segment parameter changes using the Pentacam after uneventful phacoemulsification

This study set out to evaluate the influences of uneventful phacoemulsification on the anterior segment parameters obtained with the Pentacam rotating Scheimpflug camera and intraocular pressure (IOP). A total of 42 eyes of 34 patients (26 men, eight women) were evaluated preoperatively, and at 1, 3 and 6 months postoperatively with the Pentacam. Intraocular pressure was measured with the Goldmann applanation tonometer. The non-parametric paired t-test was used to compare preoperative and 1-, 3- and 6-month postoperative measurements of anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA) width, central corneal thickness (CCT), the central 3-, 5- and 7-mm corneal volume (CV), pupil size, and IOP. Pearson's correlation test was used to evaluate the relationships between IOP and ACD, ACV and ACA width. The differences between ACD, ACV, ACA and IOP values taken preoperatively and those taken postoperatively at 1, 3 and 6 months were statistically significant (p<0.05). The differences between CCT, central 3-, 5- and 7-mm CV, and pupil size measurements taken preoperatively and those taken postoperatively at 1, 3 and 6 months were not statistically significant (p>0.05). The decrease in IOP was not correlated with the changes in ACD, ACV and ACA (p>0.05). Uneventful phacoemulsification significantly reduced IOP, increased ACD and ACV, and widened the ACA. However, alterations in CV, CCT and pupil size values were not statistically significant. Alterations in ACD, ACV, ACA and IOP remain stable after the first month of surgery.

Enalaprilat and enalapril maleate eyedrops lower intraocular pressure in rabbits

This study aimed to develop low-viscosity aqueous eyedrops containing enalaprilat and its prodrug enalapril maleate in solution, and to evaluate the eyedrops in rabbits. Aqueous eyedrops with hydroxypropyl-beta-cyclodextrin containing 0.01-2.9% (w/v) enalaprilat, 1.0% (w/v) enalapril maleate with cyclodextrin or 0.5% (w/v) timolol were prepared. The eyedrops were administered to rabbits and intraocular pressure (IOP) was measured at various time intervals after the administration and the results (mean of 10 experiments +/- standard error of the mean) are expressed as the change from baseline (24.7 +/- 3.3 mmHg). Enalaprilat possessed sufficient stability to be formulated as an aqueous eyedrop solution with a shelf-life of several years at room temperature. The maximum decline in IOP after topical administration of one drop of 2.9% enalaprilat solution was 6.2 +/- 0.7 mmHg at 4 hours after administration. Duration of activity exceeded 10 hours. A 1% enalaprilat solution lowered IOP by 4.4 +/- 0.8 mmHg at 4 hours after administration and had similar duration, and was more potent than 0.5% timolol. The enalapril maleate eyedrops resulted in delayed action, showing maximum potency at 10-22 hours after administration and duration of up to 32 hours. Enalaprilat eyedrops lower IOP in rabbits. The decline in IOP is proportional to the concentration of dissolved enalaprilat in low-viscosity aqueous eyedrop formulations.