Normal Range Of Intraocular Pressure Research Articles

Intraocular Pressure in Chinese Edible Frogs (Hoplobatrachus ruguosus) by Rebound Tonometry: Comparing Sex and Use of Anesthesia

Abstract The objective of this study was to describe the intraocular pressure (IOP) findings in a population of Chinese edible frogs (Hoplobatrachus rugulosus) sold in wet markets across Hong Kong and to characterize the influence of sex and anesthesia. One hundred animals were evaluated and ninety-six were included in this study. All frogs included appeared ophthalmologically normal upon gross examination. Intraocular pressure was evaluated with rebound tonometry (TonoVet Plus® setting “d”) on c conscious frogs and under anesthesia. General anesthesia was induced with MS-222 (tricaine methanesulfonate) 2 g/L by immersion. After IOP measurements, the frogs were euthanized with intravenous pentobarbital (200 mg/ml) and sex was confirmed on postmortem examination. Mean (+/− SD) IOP values were significantly decreased under MS-222 anesthesia in males (14.7 +/− 2.8 mmHg; P < 0.0001) and females (14.7 +/− 2.4 mmHg; P < 0.0001) compared to conscious readings (16.3 +/− 2.1 mmHg and 16.3 +/− 2.1 mmHg, respectively). There was no significant difference in IOP found between males and females before or after anesthesia. There was no significant difference between the right and left eye in males and females before or after anesthesia. The results of this study establish a normal range of IOP for this species and are comparable to previous published reports of IOP in anurans.

Characterizing the Aging Process of the Human Eye: Tear Evaporation, Fluid Dynamics, Blood Flow, and Metabolism-Based Comparative Study.

Eye temperature and intraocular pressure are two measurable parameters that can be monitored as a health index with aging. Deviations from the normal range of intraocular pressure and temperature lead to the formation of many diseases. This study has been carried out to evaluate the relations between the physiological and anatomical changes of the eye with aging using mathematical modeling. 2D computer-aided design of the human eye has been developed for two major groups: 21 to 30 years and 41 to 50 years. The computer simulation has been carried out to determine the effects of physiological changes of tear evaporation, fluid dynamics, blood flow, and metabolism of eye tissues with aging. The simulation has been carried out in the standing and the supine position of a human body. The rate of temperature change is – 0.0075 K per year in the standing position and – 0.007 K per year in the supine position because of the modeled anatomical and physiological effects. All the three simulation parameters of this study, the temperature of the human eye, the intraocular pressure, and the aqueous humor flow velocity, have been compared with the recent practical and simulation-based experiments to validate our results.

Comparison of Goldmann applanation tonometry and Icare tonometry

AbstractPurposeTo compare the variation of intraocular pressure (IOP) measured with Goldmann applanation tonometry (GAT) and Icare tonometry, and further determine if the two methods were calibrated to each other.MethodsTotally 20 subjects within normal IOP range were evenly divided into two method groups. In one group the IOPs were measured only with GAT and in another group only with Icare. With each method, the IOPs were measured at two occasions and at each occasion 3 measurements were performed.ResultsThe estimated variance of IOP among occasions with GAT was 7 times lower than that with Icare. The estimated variance among measurements with GAT was 3 times lower than with Icare. The 95% confidence intervals for mean IOPs were 11.9 ± 1.0 mmHg for GAT and 14.2 ± 1.4 mmHg for Icare.ConclusionsThe lower variations among both measurements and occasions with GAT than with Icare, indicate the reliability is different between the methods. The two methods are not calibrated to each other.

Efficacy of intracameral preservative-free triamcinolone acetonide in pediatric cataract surgery: a meta-analysis.

The aim of this study is to evaluate the efficacy of intracameral preservative-free triamcinolone acetonide (TA) on reducing inflammatory reactions after pediatric cataract surgery. Researches were comprehensively searched in PubMed, Embase, and the Cochrane Central Register of Controlled Trials up to 30 November, 2019. Data of interest were extracted and analyzed by Review Manager 5.2. The primary outcome was cell deposits. The secondary outcomes included posterior synechias, fibrinous anterior chamber reaction, visual axis obscuration, and posterior capsule opacification. The odds ratio (OR), weight mean difference (WMD), and their 95% confidence intervals (95% CI) were used to assess the strength of the association. In total, 45 articles were obtained. Finally, 5 studies with a total of 308 eyes were enrolled in this meta-analysis. Among these, 134 eyes underwent intracameral TA treatment and 174 eyes did not. In intracameral TA treatment group, the incidence of cell deposits (OR = 0.35, 95% CI 0.16-0.76, P = 0.008), posterior synechias (OR = 0.44, 95% CI 0.23-0.86, P = 0.02), and fibrinous anterior chamber reaction (OR = 0.12, 95% CI 0.01-1.05, P = 0.05) were lower compared to those in patients without intracameral TA treatment. Meanwhile, the incidence of visual axis obscuration (OR = 0.10, 95% CI 0.01-0.85, P = 0.04) and posterior capsule opacification (OR = 0.09, 95% CI 0.02-0.55, P = 0.009) were also reduced significantly. The intraocular pressure (IOP) was evaluated at the first month postoperatively (WMD = 0.84 mmHg, 95% CI 0.14-1.53, P = 0.02), but within the normal range. There was no difference of IOP between two groups at 6 months or above after operation (P = 0.93). The intracameral preservative-free TA in pediatric cataract surgery contributed to much less inflammatory reaction with the normal IOP range.

Distribution of intraocular pressure in healthy Iranian children: the Shiraz Pediatric Eye Study

PurposeTo describe the mean and normal range of intraocular pressure (IOP) and its associations in healthy Iranian school children using the noncontact tonometer. MethodsIn this cross-sectional study as part of the Shiraz Pediatric Eye Study, a stratified random sampling was performed among elementary school children of Shiraz, Iran. Basic demographics and socioeconomic status of households, past medical history, drug history, and eye health history were collected for each eligible student. Children underwent complete ophthalmic examination. Axial length, corneal curvature, and anterior chamber depth were measured using the IOL-Master 500. ResultsOf 2,001 eligible children, 1,901 (95.0%; 3,802 eyes) with a mean age of 9.1 ± 1.6 years (standard deviation; range, 6-12 years) had reliable IOP. The mean spherical equivalent refraction was 0.5 ± 1.3 D for the right eye and 0.6 ± 1.2 D for the left eye. Mean IOP in the right eye was 15.1 ± 2.5 mm Hg (median, 15.0; range, 8.0–27.0 mm Hg); in the left eye, 15.2 ± 2.5 mm Hg (median, 15.0; range, 9.0–28.0 mm Hg). In multiple regression analyses, the mean IOP was significantly lower among asthmatic children compared to normal participants (P = 0.007). The measured IOP was significantly higher in myopic participants than hyperopic patients (P = 0.003). ConclusionsThis study provides a useful normative IOP database using the noncontact tonometer for healthy Iranian school children.

Comparability of three intraocular pressure measurement: iCare pro rebound, non-contact and Goldmann applanation tonometry in different IOP group

BackgroundMeasurement of intraocular pressure (IOP) is essential for glaucoma patients. Many factors such as central corneal thickness (CCT) can affect the accuracy of IOP measurement. The purpose of this study was to evaluate the agreement of IOP measured by non-contact tonometer (NCT), iCare pro rebound tonometer (iCare), and Goldmann applanation tonometer (GAT) in different IOP group.MethodsThis was a Hospital-based cross-sectional study. Two hundred subjects were enrolled in this study. All subjects underwent IOP measurement using an NCT–iCare–GAT sequence. Bland-Altman, Pearson correlation and intraclass correlation analysis were performed using SPSS 17.0 software. The influence of CCT on each IOP measurement methods was evaluated by linear regression analysis.ResultsThe mean difference (Δ) of NCT–GAT did not differ from (Δ) iCare–GAT in IOP < 10 and 10–21 mmHg group. However, (Δ) NCT–GAT was significantly higher than (Δ) iCare–GAT in IOP 22–30 and > 30 mmHg group (P < 0.05). Bland–Altman analysis showed significant agreement between the three devices (P < 0.01). IOP measurements of the three methods were significantly correlated with CCT (P < 0.01).ConclusionsICare pro shows a higher agreement with GAT over a wide range of IOP compared with NCT. The consistency between the three tonometers was similar in a low and normal IOP range. However, NCT shows a greater overestimate of IOP in moderate and higher IOP group. The variability of IOP measurement affected by CCT is NCT > iCare pro > GAT.

Intraocular Pressure and Its Associations in a Russian Population: The Ural Eye and Medical Study

To assess the normal distribution of intraocular pressure (IOP) and its associations with ocular, medical, and socioeconomic factors in a Russian population. Population-based cross-sectional study. The Ural Eye and Medical Study conducted in a rural and urban area in Ufa/Bashkortostan included 5899 (80.5%) participants out of 7328 eligible individuals aged 40+ years. IOP was measured by noncontact tonometry. After exclusion of individuals after glaucoma surgery or with antiglaucomatous therapy, mean IOP was 13.6 ± 3.8mm Hg (median: 13mm Hg; range: 3-49mm Hg; 95% confidence interval [CI]: 8-23mm Hg). The IOP range within the mean ± 2 standard deviations was 6.0-21.2mm Hg. In multivariable analysis higher IOP was associated (regression coefficient r: 0.40) with the systemic parameters of female sex (nonstandardized regression coefficient B: 0.44; 95%CI: 0.22, 0.66; standardized regression coefficient beta: 0.06; P < .001), urban region of habitation (B: -0.27; 95% CI: 0.51, 0.03; beta: 0.03; P= .03), Russian ethnicity (B: 0.47; 95% CI: 0.20, 0.74; beta: 0.05; P= .001), higher body mass index (B: 0.06; 95% CI: 0.04, 0.08; beta: 0.08; P < .001), lower physical activity score (B: -0.02; 95% CI: -0.03, -0.002; beta: -0.03; P= .02), higher prevalence of diabetes mellitus (B: 0.42; 95% CI: 0.08, 0.76; beta: 0.03; P= .02), higher systolic blood pressure (B: 0.01; 95% CI: 0.01, 0.02; beta: 0.08; P < .001), fewer days with intake of fruits (B: -0.07; 95% CI: -0.12, -0.01; beta: 0.03; P= .01), lower blood concentration of bilirubin (B: -0.01; 95% CI: -0.02, -0.003; beta: -0.04; P=.008) and urea (B: -0.11; 95% CI: -0.17, -0.04; beta: -0.04; P= .003), worse best-corrected visual acuity (B: 0.64; 95% CI: 0.38, 0.90; beta: 0.13; P< .001), thicker central corneal thickness (B: 0.036; 95% CI: 0.033, 0.039; beta: 0.32; P<.001), higher anterior corneal refractive power (B: 0.11; 95% CI: 0.04, 0.18; beta: 0.05; P=.003), lower anterior chamber depth (B: -0.57; 95% CI: -0.83, -0.30; beta: -0.07; P < .001) (or lower prevalence of cataract surgery [B: -0.78; 95% CI: -1.44, -0.13; beta: -0.03; P= .02]), longer axial length(B:0.30; 95% CI: 0.18, 0.42; beta: 0.07; P< .001), and higher prevalence of pseudoexfoliation (B: 1.08; 95% CI: 0.52, 1.63; beta: 1.01; P<.001). Measured IOP decreased by 0.36mm Hg (95% CI: 0.33, 0.39) for each increase in central corneal thickness by 10μm. IOP was associated with a multitude of systemic and ocular parameters, the associations of which may be considered in defining the normal range of IOP.

Effect of Tourmaline-added Eyeglass Frames on Normalization of Intraocular Pressure

Purpose : Tourmaline, a natural ore material, was applied to the entire eyeglasses to observe changes in intraocular pressure (IOP), one of the factors related to human ocular metabolism.Methods : After making eyeglass frames by mixing TR-90, which is the main material of eyeglass frames and 7wt% of tourmaline, The changes of intraocular pressure before and after wearing of tourmaline spectacle frames were divided into low, middle and high groups according to the intraocular pressure in 90 normal subjects (46 men and 44 women) in their 20s.Results : Total intraocular pressure was a significantly decreased to -4.14% (p<0.000) in the right eye after wearing tourmaline frames, and significantly decreased to –6.39 % (p<0.000) and –4.64 % (p<0.017) in the High and Middle groups, respectively. Total intraocular pressure was a significantly decreased to –2.74 % (p<0.004) in the left eye, and –4.58 % (p<0.000) in the High group only showed statically significant value.Conclusion : In this study, the spectacle frame containing 7wt% tourmaline was used and it was confirmed that the intraocular pressure was significantly decreased after wearing the spectacle frame, and it became close to the average value of the normal intraocular pressure range. The results of this study showed that tourmaline, which has the effect of promoting the metabolism and blood circulation of the body, has an effect on the normalization of the intraocular pressure by attaching it to the spectacle frame.

Dietary Niacin and Open-Angle Glaucoma: The Korean National Health and Nutrition Examination Survey.

Glaucoma is a leading cause of loss of sight. High intraocular pressure (IOP) is the most critical risk factor. However, glaucoma develops even within a normal IOP range. Normal tension glaucoma (NTG) is more common in Asia, whereas high tension glaucoma is more common in Western countries. The pathogenesis of glaucoma, especially NTG, is poorly understood. We evaluated the correlation between dietary nutrient intake and glaucoma using data from subjects ≥40 years old from the ongoing, nationwide, population-based study, the Korean National Health and Nutrition Examination Survey V (2008–2012). Dietary intake was determined using the 24 h recall method. Fiber (g/day), ash (g/day), calcium (mg/day), phosphorus (mg/day), iron (mg/day), sodium (mg/day), potassium (mg/day), β-Carotene (μg/day), retinol (μg/day), vitamin A (μg Retinol Equivalents/day), thiamine (mg/day), riboflavin (mg/day), niacin (mg/day), and vitamin C (mg/day) were included in nutrient intake data. All nutrient intake was divided into quartiles. The mean IOP did not differ according to quartiles from any nutrients (all p > 0.05). After adjusting for age, gender, income status, education level, smoking, alcohol consumption, physical activity, diabetes, hypertension, IOP, and total energy, the intake of niacin was associated with glaucoma (p = 0.013). Among subjects with IOP ≤ 21 mmHg, only niacin was related to glaucoma in a multivariate analysis (p = 0.022). Dietary nutrient intake was associated with open-angle glaucoma independent of IOP. Individuals with NTG showed lower intake of niacin among nutrients. This finding suggests the possibility that proper diet counseling may be another modifiable factor, aside from IOP, particularly among patients with NTG.

INDIVIDUAL NORMAL RANGE OF INTRAOCULAR PRESSURE IN EARLY GLAUCOMA DIAGNOSTICS

Aim: to demonstrate the benefit of individual normal range of intraocular pressure (inIOP) in early glaucoma diagnostics. Material and methods. The study included 40 patients (40 eyes) without established glaucoma diagnosis, no hypotensive regimen and average IOP level corresponding with the typical norm of ≤ 21 mm Hg, but at the same time exceeding inIOP level of ≤ 13.4 ± 4.1 mm Hg. All patients underwent visometry, biomicroscopy, tonometry, inIOP calculation, standard automated perimetry, retinal tomography. Follow-up period was 12 months. Results and discussion. At the baseline examination we revealed glaucomatous changes of morphofunctional parameters. After IOP level reduction to correspond with the individual normal range, all parameters were stabilized and showed no progression during the follow-up period. Conclusion. The method of individual normal range of intraocular pressure calculation may prove to be beneficial for early glaucoma diagnostics, as well as treatment tactics assessment.

Distribution of IOP measured with an air puff tonometer in a young population

PurposeTo determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device. MethodsSubjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer. ResultsOf the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22–16.53] in the total sample, 16.14 mmHg (95% CI: 15.84–16.45) in men, and 16.48 mmHg (95% CI: 16.31–16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP. ConclusionsIn the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

Computing the influences of different Intraocular Pressures on the human eye components using computational fluid-structure interaction model.

Intraocular Pressure (IOP) is defined as the pressure of aqueous in the eye. It has been reported that the normal range of IOP should be within the 10-20 mmHg with an average of 15.50 mmHg among the ophthalmologists. Keratoconus is an anti-inflammatory eye disorder that debilitated cornea unable to reserve the normal structure contrary to the IOP in the eye. Consequently, the cornea would bulge outward and invoke a conical shape following by distorted vision. In addition, it is known that any alterations in the structure and composition of the lens and cornea would exceed a change of the eye ball as well as the mechanical and optical properties of the eye. Understanding the precise alteration of the eye components' stresses and deformations due to different IOPs could help elucidate etiology and pathogenesis to develop treatments not only for keratoconus but also for other diseases of the eye. In this study, at three different IOPs, including 10, 20, and 30 mmHg the stresses and deformations of the human eye components were quantified using a Three-Dimensional (3D) computational Fluid-Structure Interaction (FSI) model of the human eye. The results revealed the highest amount of von Mises stress in the bulged region of the cornea with 245 kPa at the IOP of 30 mmHg. The lens was also showed the von Mises stress of 19.38 kPa at the IOPs of 30 mmHg. In addition, by increasing the IOP from 10 to 30 mmHg, the radius of curvature in the cornea and lens was increased accordingly. In contrast, the sclera indicated its highest stress at the IOP of 10 mmHg due to over pressure phenomenon. The variation of IOP illustrated a little influence in the amount of stress as well as the resultant displacement of the optic nerve. These results can be used for understanding the amount of stresses and deformations in the human eye components due to different IOPs as well as for clarifying significant role of IOP on the radius of curvature of the cornea and the lens.

Racial differences in the extracellular matrix of the lamina cribrosa and the peripapillary sclera

PurposeTo investigate the major extracellular matrix components (ECM) of the lamina cribrosa (LC) and peripapillary sclera (PPS) in human donor eyes and to determine the differences between Korean and Caucasian eyes.MethodsPosterior segment tissues obtained from nonpathologic, age and axial length‐matched 24 Caucasian and 48 Korean donors were used. Protein and mRNA expression of major ECM components were assessed by quantitative polymerase chain reaction, immunohistochemitry, and light and electron microscopy. Biomechanical analysis was performed by obtaining stress‐strain curves of the PPS and LC.ResultsCollagen and elastin were significantly more abundant in Korean eyes as measured by quantitative polymerase chain reaction and immunohistochemical staining. ECM modulating enzyme, lysyl oxidase like‐2 expression was elevated in the PPS and LC of Korean eyes. The width of PPS around the LC region was larger in Korean eyes compared to Caucasian eyes. Collagen fibers had a greater preferred directionality and smaller fibril diameter in the PPS region in Korean eyes observed by electron microscopy. The mechanical properties of the LC and PPS produced greater strain in Korean eyes measured by strain‐stress relationship. Increased strain was more pronounced in the PPS region in Korean eyes.ConclusionsThe LC and PPS are more easily deformed by similar pressures in Korean eyes compared to Caucasian eyes. Racial differences in the ECM composition and microscopic architecture may contribute to the greater deformation of the LC and PPS and this could contribute to the susceptibility for glaucoma under normal intraocular pressure range in Korean eyes.

The applicability of correction factor for corneal thickness on non-contact tonometer measured intraocular pressure in LASIK treated eyes

PurposeTo determine the applicability of central corneal thickness (CCT) based correction factor for non-contact tonometer (NCT) measured intraocular pressure (IOP) readings. MethodA prospective, non-randomized study involved 346 eyes of 173 consecutive patients with age ⩾21years undergoing laser-assisted in situ keratomileusis (LASIK) for myopia and/or myopic astigmatism. The CCT and IOP were measured before and after the LASIK procedure. The IOP pre and post-LASIK was compared after applying the correction factor for CCT. Patients not completing the 3month postoperative follow-up were excluded. ResultsThe median spherical equivalent before undergoing LASIK was −4.25D (inter-quartile range, −3.25D). The mean preoperative CCT was 536.82±33.71μm which reduced to 477.55±39.3μm (p<0.01) post-LASIK. The mean IOP reduced from a preoperative value of 14.6±2.32mmHg to 10.64±2.45mmHg postoperatively (p<0.01). On applying correction for the corneal thickness, the pre and postoperative IOP was 15.14±2.8mmHg and 15.37±2.65mmHg (p=0.06) respectively with a strong positive correlation (r=0.7, p<0.01). Three hundred eyes (86.7%) had an absolute difference in IOP of less than 3.0mmHg post-CCT correction which is within the retest variability of NCT. Only 46 eyes (13.3%) had an absolute difference of more than 3.0mmHg. ConclusionThe modified Ehler’s correction algorithm used in this study can be effectively applied in the normal IOP range in a majority of patients.

Effects of blood flow properties on ocular hemodynamics

to study the effects of blood rheology on ocular blood flow (OBF) parameters and estimated individual normal range of intraocular pressure (IOP). A total of 15 patients (15 eyes) taking warfarin were enrolled. Volumetric parameters and linear velocity of OBF under warfarin treatment and after its cessation were obtained by means of flowmetry (Paradigm's Blood Flow Analyzer) and color Doppler flow mapping (Voluson 730), respectively. On the basis of flowmetry results an individual normal range of IOP was calculated in all patients. Pulsatile OBF does not appear to correlate with warfarin-induced changes in blood rheology (p = 0.09), however, depends on IOP fluctuations (p = 0.02). Resistance index of retinal vessels is found to rise significantly with increasing blood viscosity (p < 0.05). The use of warfarin, an indirect thrombin inhibitor, has no effect on estimated individual normal range of IOP, which is crucial for glaucoma diagnosis and monitoring.

Ocular blood flow and carotid artery malfunction

to evaluate ocular hemodynamics and informativity of estimated individual normal range of intraocular pressure (IOP). A total of 12 patients (22 eyes) with carotid artery malfunction were examined. Ocular blood flow (OBF) and IOP were measured with Ocular Blood Flow Analyzer. Actual OBF was then compared with what is considered normal for a given axial length (AL). Individual normal range of IOP was calculated according to an original formula (described in previous publications). Doppler imaging of ocular vessels enabled blood flow velocity measurement. Morphological parameters and functional status of the retina and optic nerve were judged on automated perimetry (Octopus 900) and optical coherence tomography (Cirrus HD-OCT) findings. Statistical analyses were performed using Statistica 10 software. Generally, OBF showed no correlation with the grade of carotid artery stenosis (p < 0.05), however, was significantly reduced as compared to its AL-dependent norm in patients with greater than 85% narrowing of the internal carotid artery, which can cause misestimating of their individual normal range of IOP. A negative relationship was established between the blood flow velocity in short posterior ciliary arteries and the grade of internal carotid artery stenosis (p < 0.005). Ocular blood flow deficit relative to the AL-dependent norm correlated with ophthalmic artery resistance index. OBF-based estimation of individual normal range of IOP is inexpedient in patients with greater than 80% carotid artery stenosis due to its possible influence on ocular hemodynamics. In most cases of less than 80% carotid artery stenosis OBF is adequate or slightly reduced as compared to its AL-dependent norm and thus, has no significant impact on estimated individual normal range of IOP.

A laser-induced mouse model with long-term intraocular pressure elevation.

PurposeTo develop and characterize a mouse model with intraocular pressure (IOP) elevation after laser photocoagulation on the trabecular meshwork (TM), which may serve as a model to investigate the potential of stem cell-based therapies for glaucoma.MethodsIOP was measured in 281 adult C57BL/6 mice to determine normal IOP range. IOP elevation was induced unilaterally in 50 adult mice, by targeting the TM through the limbus with a 532-nm diode laser. IOP was measured up to 24 weeks post-treatment. The optic nerve damage was detected by electroretinography and assessed by semiautomatic counting of optic nerve axons. Effects of laser treatment on the TM were evaluated by histology, immunofluorescence staining, optical coherence tomography (OCT) and transmission electron microscopy (TEM).ResultsThe average IOP of C57BL/6 mice was 14.5±2.6 mmHg (Mean ±SD). After laser treatment, IOP averaged above 20 mmHg throughout the follow-up period of 24 weeks. At 24 weeks, 57% of treated eyes had elevated IOP with the mean IOP of 22.5±2.5 mmHg (Mean ±SED). The difference of average axon count (59.0%) between laser treated and untreated eyes was statistically significant. Photopic negative response (PhNR) by electroretinography was significantly decreased. CD45+ inflammatory cells invaded the TM within 1 week. The expression of SPARC was increased in the TM from 1 to 12 weeks. Histology showed the anterior chamber angle open after laser treatment. OCT indicated that most of the eyes with laser treatment had no synechia in the anterior chamber angles. TEM demonstrated disorganized and compacted extracellular matrix in the TM.ConclusionsAn experimental murine ocular hypertension model with an open angle and optic nerve axon loss was produced with laser photocoagulation, which could be used to investigate stem cell-based therapies for restoration of the outflow pathway integrity for ocular hypertension or glaucoma.

Advances in tonometry in companion animals

THE measurement of intraocular pressure (IOP) is an important part of the complete ophthalmic examination and is particularly applicable in the diagnosis and management of uveitis and glaucoma. The normal...

A Potential Neuroprotective Role of Apolipoprotein E-containing Lipoproteins through Low Density Lipoprotein Receptor-related Protein 1 in Normal Tension Glaucoma

Glaucoma is an optic neuropathy and the second major cause of blindness worldwide next to cataracts. The protection from retinal ganglion cell (RGC) loss, one of the main characteristics of glaucoma, would be a straightforward treatment for this disorder. However, the clinical application of neuroprotection has not, so far, been successful. Here, we report that apolipoprotein E-containing lipoproteins (E-LPs) protect primary cultured RGCs from Ca(2+)-dependent, and mitochondrion-mediated, apoptosis induced by glutamate. Binding of E-LPs to the low density lipoprotein receptor-related protein 1 recruited the N-methyl-d-aspartate receptor, blocked intracellular Ca(2+) elevation, and inactivated glycogen synthase kinase 3β, thereby inhibiting apoptosis. When compared with contralateral eyes treated with phosphate-buffered saline, intravitreal administration of E-LPs protected against RGC loss in glutamate aspartate transporter-deficient mice, a model of normal tension glaucoma that causes glaucomatous optic neuropathy without elevation of intraocular pressure. Although the presence of α2-macroglobulin, another ligand of the low density lipoprotein receptor-related protein 1, interfered with the neuroprotective effect of E-LPs against glutamate-induced neurotoxicity, the addition of E-LPs overcame the inhibitory effect of α2-macroglobulin. These findings may provide a potential therapeutic strategy for normal tension glaucoma by an LRP1-mediated pathway.

Age variations in intraocular pressure in a cohort of healthy Austrian school children

Limited data exist detailing the normal range of intraocular pressure (IOP) for healthy school age children. This study aims to describe the mean and normal range of IOP measurements that may be expected using the Icare rebound tonometer and to examine associations between visual function measures and IOP. Six measurements of IOP from each eye were obtained from 211 normal children aged 6-15 years (79 females and 132 males) using the Icare tonometer. Other measures of visual function obtained included: visual acuity, non-cycloplegic retinoscopy, amplitude of accommodation, accommodative facility, and accommodative response. Statistical analysis (Mann-Whitney U test) demonstrated that the male subjects were more likely to have higher IOP measurements than the female subjects (mean IOP males 15.02 mm Hg (SD 2.19), mean IOP females 14.44 (SD 2.01) P=0.041). Analysis (Spearman's rho) showed a statistically significant association between age and IOP (right eye) in males (P<0.001) but no association for females (P=0.459). Using Spearman's rank analysis, statistically significant associations were found between IOP and amplitude of accommodation in males, for the whole data set (P=0.09) and for data up to age 11 (P<0.001). For females no statistically significant association was found for the whole data set (P=0.253) or for data up to age 11 (P=0.08). IOP was not significantly associated with visual acuity, refractive error, accommodative facility, or accommodative response. This study provides useful normative IOP data using the Icare tonometer for a European cohort of school age children.