Mm Hg Increase In Intraocular Pressure Research Articles

Plexus-Specific Retinal Capillary Blood Flow Analysis Using Erythrocyte Mediated Angiography and Optical Coherence Tomography Angiography.

The purpose of this study was to identify and measure plexus-specific absolute retinal capillary blood flow velocity and acceleration in vivo in both nonhuman primates (NHPs) and humans using erythrocyte mediated angiography (EMA) and optical coherence tomography angiography (OCTA). EMA and OCTA scans centered on the fovea were obtained in 2 NHPs and 11 human subjects. Scans were also obtained in NHP eyes while IOP was experimentally elevated. Erythrocyte velocity and acceleration in retinal arteries, capillaries, and veins were measured and capillaries were categorized based on location within the superficial vascular (SVP), intermediate capillary (ICP), or deep capillary plexus (DCP). Generalized linear mixed models were used to estimate the effects of intraocular pressure (IOP) on capillary blood flow. Capillary erythrocyte velocity at baseline IOP was 0.64 ± 0.29 mm/s in NHPs (range of 0.14 to 1.85 mm/s) and 1.55 ± 0.65 mm/s in humans (range of 0.46 to 4.50 mm/s). Mean erythrocyte velocity in the SVP, ICP, and DCP in NHPs was 0.69 ± 0.29mm/s, 0.53 ± 0.22mm/s, and 0.63 ± 0.27mm/s, respectively (P = 0.14 for NHP-1 and P = 0.28 for NHP-2). Mean erythrocyte velocity in the human subjects did not differ significantly among SVP, ICP, and DCP (1.46 ± 0.59 mm/s, 1.58 ± 0.55 mm/s, and 1.59 ± 0.79 mm/s, P = 0.36). In NHPs, every 1 mm Hg increase in IOP was associated with a 0.13mm/s reduction in arterial velocity, 0.10mm/s reduction in venous velocity, and 0.01 mm/s reduction in capillary velocity (P < 0.001) when accounting for differences in mean arterial pressure (MAP). Blood flow by direct visualization of individual erythrocytes can be quantified within capillary plexuses. Capillary velocity decreased with experimental IOP elevation.

Intraocular pressure, primary open-angle glaucoma and the risk of retinal vein occlusion: A Mendelian randomization mediation analysis.

The etiological connection between intraocular pressure (IOP) and the risk of retinal vein occlusion (RVO) remains elusive, particularly regarding whether this risk emanates from the direct influence of elevated intraocular pressure (IOP), irrespective of the presence of primary open-angle glaucoma (POAG), or if it arises as a consequence of the sequelae of POAG. Therefore, we conducted a Mendelian Randomization (MR) mediation analysis to elucidate the mediating role of POAG in the association between IOP and RVO. We identified 47 single-nucleotide polymorphisms (SNPs) associated with IOP (P-value < 5 × 10-8) leveraging data from a genome-wide association study (GWAS) (N = 97,653) obtained from the UK Biobank and 50 SNPs associated with POAG (P-value < 5 × 10-8) from a GWAS meta-analysis (16,677 cases and 199,580 controls). We related these SNPs with RVO using a GWAS of 775 RVO cases and 376,502 controls from FinnGen. By utilizing univariable and multivariable MR analyses we calculated the total effect of IOP on RVO and estimated the degree to which POAG mediates this association. MR analyses showed that higher IOP is associated with higher RVO risk (odds ratio of RVO per 1 mmHg increase in IOP: 1.53; 95% confidence interval: 1.04 to 2.26; p-value = 0.03). Moreover, our MR mediation analysis suggested that 91.6% of the total effect of IOP on RVO risk was mediated through POAG. The primary results were consistent with estimates of pleiotropy-robust MR methods. Our findings suggest that higher IOP increases the risk of RVO and that the majority of this effect is mediated through POAG.

A comparison of rebound and applanation tonometry in children with and without primary congenital glaucoma

Background: Intraocular pressure (IOP) measurement should be accurate in a paediatric population with primary congenital glaucoma (PCG).Aim: This study aims to investigate the difference between the change in IOP measurements using rebound tonometry (RBT) and handheld applanation tonometry (AT) (Perkins applanation tonometer [PAT]) in patients with and without PCG.Setting: Johannesburg, South Africa.Methods: Measurements were taken under anaesthesia, using RBT and AT at 0 min, 5 min and 10 mins after induction and prior to intubation. Corneal pachymetry and corneal diameters were measured.Results: Sixty-five children were included, 19 with PCG and 46 without PCG. The mean age (standard deviation [s.d.]) was 3.2 (2.25) years and 4.8 (2.4) years, respectively. The overall mean difference in IOP between RBT and PAT across both PCG and non-PCG groups was found to be 4.92 mmHg (95% confidence interval [CI]: 2.80 – 7.03) p 0.001, with RBT having higher readings. This difference was greater in the PCG group, with the IOP difference of 9.05 mmHg (95% CI: 2.6 – 15.5) p = 0.004. Mean corneal pachymetry (s.d.) was 585.6 (81.48) µm in the PCG group and 518.31 (39.9) µm in the non-PCG group. Univariate analysis showed that IOP was significantly related to corneal pachymetry, with a 11 mmHg increase in IOP for every 100 μm change in corneal thickness for measurements done with RBT (p 0.001), compared to 4 mmHg using PAT (p = 0.008).Conclusion: Intraocular pressure measurements done with RBT in children with and without PCG were overestimated compared to PAT.Contribution: This difference was more pronounced in PCG patients. In addition, IOP was significantly related to corneal thickness.

Silicone Oil and Intraocular Pressure: Unraveling the Post-Vitrectomy Relationship

Aim of the Study: To assess the potential influence of silicone oil tamponade following vitrectomy on the early elevation of intraocular pressure (IOP), a critical factor associated with the emergence of secondary glaucoma in individuals with proliferative changes in the vitreous and retina.  Subjects and Methodology: This study was carried out in a prospective manner within the Department of Ophthalmology at Katuri Medical College and Hospital from January 2023 to January 2024, lasting for a duration of 1 year. The research involved 110 participants categorized into three groups based on their medical histories. The control cohort, comprising 40 patients, went through vitrectomy with either air or saline solution as a tamponade. The second group, consisting of 40 patients with retinal detachment and proliferative retinopathy changes, have undergone vitrectomy with silicone oil tamponade. The third group, comprising 30 patients diagnosed with diabetic retinopathy, underwent vitrectomy with silicone oil tamponade. This study encompassed the assessment of intraocular pressure’s (IOP) and gonioscopic findings one month before and after vitrectomy for all the participants. The primary focus of the analysis was the comparison of IOP values across the different groups.  Conclusion: The results indicated that there was no statistically notable contrast in intraocular pressure (IOP) values prior to and following the vitrectomy procedure within the control group (p=0.104). Additionally, there was no substantial difference in preoperative IOP values among the three groups of patients. However, a noteworthy distinction in IOP values was observed during one-month post-vitrectomy, particularly in patients who underwent silicone oil tamponade. This suggests that the use of silicone oil tamponade had a notable impact on intraocular pressure in these patients after the surgical procedure. The study observed that, a month Following vitrectomy, the mean intraocular pressure (IOP) values in individuals with silicone oil tamponade were notably elevated in comparison to the control group (p&lt;0.05). However, when examining individuals with retinal detachment and individuals with diabetic retinopathy changes, did not exhibit a statistically notable variance in IOP one-month post-vitrectomy (p=0.331). Nevertheless, the qualitative examination exposed a 2 mmHg increase in intraocular pressure (IOP) in the diabetic retinopathy cohort. This study indicates that there exists no significant variance in angle width prior to and following vitrectomy among various groups included. Silicone oil in emulsified form was identified in 18% of the individuals with retinal detachment and in 17% of those with diabetic retinopathy, found in the chamber angle. Moreover, within the cohort of individuals with diabetic retinopathy, 10% of patients demonstrated this attribute of angle neovascularization one-month post-vitrectomy. The rise in intraocular pressure (IOP) in the initial postoperative phase can be linked to the introduction of silicone oil into the vitreous cavity following vitrectomy. The emulsification of silicone oil might be a factor in the early elevation of intraocular pressure (IOP), particularly in individuals with diabetes exhibiting angle neovascularization, potentially hastening the development of secondary glaucoma.

Relationship between Diurnal Variation in Intraocular Pressure and Central Corneal Power.

Relationship between intraocular pressure (IOP) change and central corneal curvature is complicated by measurement techniques and corneal biomechanical parameters. Findings from this study indicate that it is worthwhile to observe the association between diurnal change in IOP and corneal power. This study aimed to investigate the relationship between the diurnal change in IOP and central corneal power among eyes with and without myopia. Sixty healthy eyes of 24 emmetropes and 36 myopes were recruited for this cross-sectional study. Both anterior and posterior central corneal powers of the steep (Ks), flat (Kf), mean meridian (Km), best-fit spheres, and central corneal thickness were recorded followed by the IOP (Goldmann-correlated IOP [IOPg] and corneal-compensated IOP) and corneal biomechanics (corneal hysteresis and corneal resistance factor). Measurements were obtained every 3 hours from 9.30 am to 6.30 pm . Linear-mixed model was used to determine the relationship between the change in IOP and the associated change in corneal measurements (adjusted for age, sex, refractive error, central corneal thickness, and biomechanics) among the myopic and nonmyopic eyes. Group mean, amplitude of change, and the diurnal change in IOPg were (mean ± standard deviation) 15.14 ± 2.50, 3.33 ± 1.44, and 1.81 ± 1.25 mmHg, respectively. Overall, an IOP increase was associated with a decrease in the adjusted anterior corneal powers. Myopic eyes were associated with a decrease of 0.04 D (95% confidence interval [CI], 0.07 to 0.01 D; P = .02) in Ks and 0.03 D (95% CI, 0.06 to 0.001 D; P = .047) in Kf per mmHg increase in IOP, whereas for emmetropes, per mmHg increase in IOP only flattened the Kf by 0.03 D (95% CI, 0.06 to 0.004 D; P = .02). Change in anterior corneal power was inversely related to the change in IOPg, with myopic and nonmyopic eyes reporting a significant but differential impact of IOP. Clinicians must keep in mind the impact of large IOP fluctuation on the anterior corneal power.

The Effect of Achieving Target Intraocular Pressure on Visual Field Worsening

To estimate the effect of achieving target intraocular pressure (IOP) values on visual field (VF) worsening in a treated clinical population. Retrospective analysis of longitudinal data. A total of 2852 eyes of 1688 patients with glaucoma-related diagnoses treated in a tertiary care practice. All included eyes had at least 5 reliable VF tests and 5 IOP measures on separate visits along with at least 1 target IOP defined by a clinician on the first or second visit. The primary dependent variable was the slope of the mean deviation (MD) over time (decibels [dB]/year). The primary independent variable was mean target difference (measured IOP - target IOP). We created simple linear regression models and mixed-effects linear models to study the relationship between MD slope and mean target difference for individual eyes. In the mixed-effects models, we included an interaction term to account for disease severity (mild/suspect, moderate, or advanced) and a spline term to account for thediffering effects of achieving target IOP (target difference ≤0) and failing to achieve target IOP (target difference >0). Rate of change in MD slope (changes in dB/year) per 1 mmHg change in target difference at different stages of glaucoma severity. Across all eyes, a simple linear regression model demonstrated that a 1 mmHg increase in target difference had a-0.018 dB/year (confidence interval [CI],-0.026 to-0.011; P < 0.05) effect on MD slope. The mixed-effects model shows that eyes with moderate disease that fail to achieve their target IOP experience the largest effects, with a 1 mmHg increase in target difference resulting in a -0.119 dB/year (CI,-0.168 to-0.070; P< 0.05) worse MD slope. The effects of missing target IOP on VF worsening were more pronounced than the effect of absolute level of IOP on VF worsening, where a 1 mmHg increase in IOP had a-0.004 dB/year (CI,-0.011 to 0.003; P > 0.05) effect on the MD slope. In treated patients, failing to achieve target IOP was associated with more rapid VF worsening. Eyes with moderate glaucoma experienced the greatest VF worsening from failing to achieve target IOP.

Outcome of Single Dexamethasone Implant Injection in the Treatment of Persistent Diabetic Macular Edema After Anti-VEGF Treatment: Real-Life Data from a Tertiary Hospital in Jordan

PurposeTo analyze the real-life clinical outcome of a single dexamethasone implant (DEX) injection in the treatment of persistent diabetic macular edema (DME) after anti-vascular endothelial growth factor (anti-VEGF) agents in a sample of the Jordanian population.MethodsAn observational case study design that involved a retrospective chart review analysis in a tertiary hospital in Amman, Jordan. Patients who showed persistent DME after receiving at least six doses of anti-VEGF agents for DME treatment were included.ResultsThe study population consisted of 72 participants (29 females, 43 males) having an average age of 66 years. All patients had best-corrected visual acuity (BCVA) less than 0.7 (6/9) and SD-OCT documented center-involved DME. The study results showed that the average baseline BCVA improved from 0.205±0.1 before DEX injection to 0.358±0.1 at 3 months post-injection (p<0.0001). The central mean thickness (CMT) showed significant improvement also (539.347±132.402 to 379.041±99.430, p<0.0001). There was a mean of 3 mmHg increase in intraocular pressure at 3 months post-injection (p<0.0001), however, only 4% of patients required medical treatment. Other inflammatory biomarkers in OCT, such as intraretinal hyper-reflective dots (HRD), showed significant improvement also (23.67±16 to 14.83±13, p<0.0001). No other significant safety concerns were noticed.ConclusionA single DEX injection showed significant clinical and anatomical improvement in DME cases that are persistent after anti-VEGF treatment in our sample, with an excellent safety profile. In case of supply shortage of intravitreal injections, which occurs frequently at our center, a single DEX injection may be utilized as an effective DME therapy. Further research is mandated to identify clinical response in a larger sample and more frequent injections.

The Association of Intraocular Pressure With Obesity and Cardiometabolic Risk in a Young Farmworker Population.

Intraocular pressure (IOP) was found to be significantly correlated with body mass index (BMI), waist circumference, and diastolic blood pressure (DBP) in a farmworker population located in the southeast Georgia, USA. BMI was correlated with IOP, independent of systemic blood pressures. Elevated IOP is a known risk factor for glaucomatous optic neuropathy and is believed to be associated with obesity and cardiometabolic diseases. The high prevalence of these conditions in the United States necessitates an evaluation of the relationship among obesity, cardiometabolic risks, and IOP among understudied younger populations. Farmworker data were collected from the annual Costa-Layman Health Fair between 2013 and 2017. Correlations of IOP with demographic factors, obesity, and cardiometabolic risks were analyzed using analysis of covariance, partial Pearson correlations, and linear regressions. In the farmworker population (n=346), the mean IOP was 15.5 mm Hg and the prevalence of ocular hypertension (IOP>21 mm Hg) was 5.5%. BMI, waist circumference, and DBP were significantly correlated (r=0.192, P=0.001; r=0.128, P=0.017; r=0.142, P=0.007, respectively) with IOP when adjusted for age, sex, and ethnicity. Each 10 mm Hg increase in DBP corresponded with a 0.51 mm Hg increase in IOP. With adjustment for age, sex, ethnicity, systolic blood pressure, and DBP, BMI remained significantly correlated with IOP (r=0.166, P=0.002). Higher IOP is associated with obesity measures including BMI and waist circumference and is correlated with DBP. These findings suggest that BMI is an independent risk factor for elevated IOP.

Outcomes of Complex Cataract Surgery in Patients with Primary Open-angle Glaucoma.

ABSTRACTAimWhether pupillary expansion during phacoemulsification causes a change in postoperative intraocular pressure (IOP) is currently unknown. However, a growing proportion of patients can present with concurrent glaucoma and cataracts, which poses an increased risk of having small pupils and makes finding the answer to this question imperative for treating physicians.Materials and methodsThis was a retrospective, observational cohort study which utilized data from 2008 to 2016 from the University Hospital, Newark, New Jersey, USA. All patients with primary open-angle glaucoma (POAG) who underwent phacoemulsification with pupillary expansion were considered for inclusion. Cases were subsequently excluded if they had prior incisional glaucoma surgery, if phacoemulsification was combined with another surgery, or if they had any incisional surgery in the eye 1 year preoperatively or postoperatively. The control group was made up of patients without POAG. The primary outcome was IOP.ResultsThirty-seven eyes from 31 glaucoma patients and 29 eyes from 28 control patients met inclusion criteria. The mean IOP in the POAG group increased from 15.0 ± 4.6 mm Hg to 15.9 ± 3.5 mm Hg after 1 year, whereas the control group decreased from 14.1 ± 3.6 mm Hg to 11.9 ± 3.9 mm Hg. Multivariate analysis showed that glaucoma was associated with a 5.56 mm Hg increase in IOP at 12 months postoperatively. The average number of glaucoma medications decreased significantly from 1.7 ± 1.4 at the baseline to 1.3 ± 1.3 after 1 year.ConclusionIn contrast with non-POAG patients, no significant drop in the mean IOP was noted after complex cataract surgery for this cohort of glaucoma patients, although medication burden significantly decreased and VA improved significantly.Clinical significancePhacoemulsification with intraoperative pupillary expansion in POAG patients may not decrease IOP after 12 months but it can decrease the number of anti-glaucoma medications they take.How to cite this articleBargoud AR, Parikh H, et al. Outcomes of Complex Cataract Surgery in Patients with Primary Open-angle Glaucoma. J Curr Glaucoma Pract 2019;13(2):62–67.

Intraocular Pressure in Patients with Neovascular Age-Related Macular Degeneration Receiving Intravitreal Aflibercept or Ranibizumab

To assess change in intraocular pressure (IOP) in patients with neovascular age-related macular degeneration (NVAMD) receiving intravitreal aflibercept injection (IAI) or ranibizumab in VEGF Trap-Eye: Investigation of Efficacy and Safety in Wet AMD (VIEW) 1 and 2 studies. Analyses from 2 randomized, active-controlled, phase III trials. A total of 2457 patients with NVAMD. Patients received IAI 2 mg every (q) 4 weeks (2q4), 0.5 mg q4 weeks (0.5q4), 2 mg q8 weeks (after 3 monthly doses; 2q8), or ranibizumab 0.5 mg q4 weeks (Rq4) for 52 weeks. At week 52, patients were switched to a variable regimen requiring at least quarterly dosing and allowing interim injections based on anatomic and visual assessment. Pre-injection IOP was analyzed in study and uninjected fellow eyes from baseline to week 96. Prespecified end points included mean change in IOP from baseline and prevalence of a >21 mmHg and >10 mmHg increase in IOP from baseline. Cumulative incidence of sustained (at 2 consecutive visits) IOP >21 mmHg, a single event of IOP >25 mmHg, and sustained IOP increase from baseline (≥5 mmHg) was also evaluated. Mean IOP change from baseline over 96 weeks in all IAI groups was consistently lower than in the Rq4 group, and this finding was replicated in both trials. In an analysis integrating both studies, the proportion of study eyes with IOP >21 mmHg at week 96 was 20.2%, 14.2%, 12.1%, and 12.5% in Rq4, 2q4, 2q8, and 0.5q4, respectively. Reduction in risk, relative to Rq4, of having sustained IOP >21 mmHg over 96 weeks was 62% (95% confidence interval [CI], 36%-78%), 50% (95% CI, 19%-70%), and 69% (95% CI, 45%-84%) for 2q4, 2q8, and 0.5q4, respectively. Risk reduction in the IAI groups for a sustained IOP increase ≥5 mmHg was 31% (95% CI, 8%-48%), 38% (95% CI, 17%-54%), and 47% (95% CI, 27%-61%), respectively. In uninjected fellow eyes, only sustained IOP >21 mmHg events were higher in the Rq4 group compared with all IAI groups. Incidence of elevated IOP in eyes with NVAMD was lower in all IAI groups than in the ranibizumab group.

Correlation analysis between central corneal thickness and intraocular pressure in juveniles in Northern China: the Jinan city eye study.

PurposeTo determine the distributions and relation of central corneal thickness (CCT) and intraocular pressure (IOP) by NT-530P in Chinese juveniles, and the effect of gender, age, height, weight and refractive errors on the CTT and IOP.MethodsCCT and IOP of 982 eyes in 514 juveniles aged from 7 to 18 years were measured with NT-530P. Multi-linear regression and ANOVA analysis were used to analyze the relation of CCT and IOP, and the effect of gender, age, height, weight, refractive condition on CCT and IOP respectively.ResultsThe mean CCT and IOP were 554.19±35.46 µm and 15.31±2.57 mmHg. There were significant correlations between the CCT and IOP values. Linear regression analysis revealed a positive correlation between CCT and IOP (r = 0.44, P<0.05). Linear regression equation: IOP = −2.35+0.032CCT, which means the IOP will increase 0.32 mm Hg for every 10-µm increase in CCT. The mean of Corrected IOP (CIOP) was 15.32±2.38 mmHg and had no relation with CCT. There was a negative correlation between refraction degree and CCT (P<0.05), but no correlation between refraction degree and IOP. Multi-linear regression model revealed that the height, weight, age and gender have no effect on the distribution of CCT and IOP respectively.ConclusionsThere is a 0.32 mmHg increase in IOP for every 10-µm increase in CCT. The height, weight, age and gender has no effect on the distribution of CCT and IOP. CCT will become thinner with myopia diopters increases in juveniles. The measurement of CCT is helpful in evaluating the actual IOP correctly.

The Effect of Prophylactic IOP-Lowering Medication after Intravitreal Dexamethasone Implantation

Purpose: To investigate the effect of prophylactic intraocular pressure (IOP)-lowering medication after intravitreal dexamethasone implantation. Methods: This is a retrospective analysis of 39 eyes undergoing intravitreal dexamethasone implantation for macular edema. Eyes were divided into two groups, those which had used prophylactic IOP-lowering medication and those which had not. IOP was measured preoperatively, at one week, and monthly until six months post-injection in each group. Results: The mean pre-injection IOP for the group that had not used prophylactic IOP-lowering medication and the group that had was 13.95 ± 3.32 mm Hg and 13.56 ± 3.71 mm Hg, the mean post-injection IOP at two months was 15.81 ± 3.75 mm Hg and 12.56 ± 5.02 mm Hg, and that at six months was 12.90 ± 2.95 mm Hg and 11.44 ± 3.59 mm Hg, respectively. The difference between the two groups was statistically significant at one week, one month, two months, and three months (p = 0.001, 0.002, 0.011, 0.035, respectively). A greater than 22 mm Hg increase in IOP was seen in four eyes (19.05%) in the group that had not used IOP-lowering medication and in one eye (5.56%) in the group that had. A greater than 5 mm Hg increase in IOP from baseline was seen in eight eyes (38.10%) in the group that had not used IOP-lowering medication and in one eye (5.56%) in the group that had. Conclusions: After intravitreal dexamethasone implantation, prophylactic IOP-lowering medication will significantly prevent IOP increase and decrease the number of patients requiring additional treatment that could cause potential damage to the retina and optic nerve. J Korean Ophthalmol Soc 2014;55(12):1828-1833

The ocular pulse amplitude at different intraocular pressure: a prospective study

To investigate changes in ocular pulse amplitude (OPA) during a short-term increase in intraocular pressure (IOP) and to assess possible influences of biometrical properties of the eye, including central corneal thickness (CCT) and axial length. In a prospective, single centre study, OPA and IOP as measured by dynamic contour tonometry (DCT) were taken before baseline- and post-OPA (delta) intravitreal injection of 0.05 ml anti-vascular endothelial growth factor agents. Analysis was performed employing linear regression with baseline- and post (delta)-OPA differences as the dependent and post-IOP as well as delta IOP as the independent variable. A multilinear regression analysis with delta OPA as the dependent variable and baseline IOP, post-IOP, CCT and axial length as independent variables was conducted. Forty eyes of 40 patients were included. IOP and OPA increased significantly after injection (IOP mean increase ± SD: 17.83 ± 9.83 mmHg, p < 0.001; OPA mean increase ± SD: 1.39 ± 1.16 mmHg, p < 0.001). For every mmHg increase in IOP, the OPA showed a linear increase of 0.05 mmHg (slope 0.05, 95% CI: 0.02-0.09, p = 0.003, r(2) = 0.20). Multiple regression analysis with delta OPA as the dependent variable revealed a partial correlation coefficient of 0.47 (p = 0.003) for post-IOP as the only significant contribution. A clear positive relationship between OPA measurements and IOP levels was shown in a clinical routine setting using DCT focusing on baseline and postinterventional comparisons of OPA values after intravitreal injections in patients with exudative age related macular degeneration. When considering the OPA for diagnostic purposes, we recommend indication of corresponding IOP values.

The Relationship of Mean Deviation Scores and Resource Utilization Among Patients With Glaucoma

To determine the relationship between mean deviation (MD) scores and resource utilization among glaucoma patients in the United States and Europe. A retrospective analysis of patient in the United States (June 1990 to January 2003, N=151) and Europe (June 1994 to July 2003, N=194) was conducted. Office visits, pressure-lowering medications, visual field examinations, and glaucoma surgeries were recorded with age, intraocular pressure (IOP), and MD. Patients with missing MD and IOP were excluded; final sample sizes were 130 in the United States and 161 in Europe. Fixed effects and logistic regression models assessed the associations between MD and visits, medication, examinations, and surgery. Number of office visits and visual field examinations significantly increased but the number of glaucoma medications decreased as MD worsened and IOP increased. Odds of trabeculoplasty within 2 years decreased by 8.1% in the United States and 9.9% in Europe with every 1.0 dB improvement in MD. Odds of trabeculectomy within 2 years increased by 13.9% in the United States and by 18.6% in Europe with every 1 mm Hg increase in IOP. In the United States, odds of trabeculectomy within 5 years increased by 12.2% with each 1.0 dB worsening in MD. MD is associated with resource utilization in glaucoma patients. Evidence supporting use of MD to predict surgery is less conclusive, possibly due to the relative low frequency of surgeries. Therapies aimed at stabilizing visual field deterioration may reduce resource use and costs associated with glaucoma; however, more research is necessary to establish whether such treatments meet common standards of cost-effectiveness.

Pascal, ICare and Goldmann applanation tonometry – a comparative study

To compare intraocular pressure (IOP) measurements by Pascal, ICare and Goldmann applanation tonometry (GAT), to evaluate the effects of central corneal thickness (CCT) and curvature on IOP measurement and to estimate the intra-observer variability. A prospective, single-centre study of 150 eyes with a wide range of pressures. Six masked IOP measurements/method; corneal thickness and curvature were studied for each eye. GAT was the reference. IOPPascal and IOPICare correlated with IOPGAT (r = 0.91, 0.89). Mean ICare measurement exceeded GAT by 2 mmHg. Pascal measured higher than GAT at low IOPs and lower at high IOPs. For every 10 mmHg increase in IOP above 31 mmHg, Pascal measured 2 mmHg lower than GAT and vice versa. CCT was correlated significantly with IOPGAT (r = 0.23) and IOPICare (r = 0.43) but not with IOPPascal (P = 0.12). CCT was correlated with age. In a subgroup (>50 years), ICare and the difference between IOPGAT and IOPPascal were affected significantly by the CCT, whereas IOPGAT and IOPPascal were not. Corneal curvature was correlated significantly with IOPGAT (r = -0.27) and IOPPascal (r = -0.26) but not with IOPICare (P = 0.60). Intra-observer variability within each set of six measurements was approximately 2 mmHg, irrespective of method. This study showed a reasonable overall correlation and concordance between the IOP obtained with the three instruments. None of the methods were completely independent of the biomechanical properties of the cornea. ICare showed a significant dependency upon CCT, whereas GAT and Pascal showed a significant dependency on corneal curvature. All methods showed intra-observer variability, which leaves room for further improvement of methods.

A 10-year follow up of ocular hypertensive patients within the Bolton Corneal Thickness Study: Can measured factors predict prognostic outcomes?

Objective This is a case note review of a cohort of patients examining the effects of central corneal thickness (CCT), presenting intraocular pressure (IOP), age and gender on the risk of progression of ocular hypertension (OHT) to primary glaucoma (POAG) over a 10-year period. Design Cohort study with retrospective case note review. Participants and methods 58 case notes from a cohort at the Bolton Royal Infirmary initially assessed 10 years ago were reviewed again. Presenting CCT, IOP, age and gender were recorded. Development of POAG was assessed by visual field and/or optic disc changes being present. Main outcome measures The effects of CCT, IOP, age and gender on the risk of progression of OHT to POAG were analysed in a multivariate logistic regression model following a preliminary univariate analysis. Results 50 out of 116 eyes developed primary open angle glaucoma over the 10-year period. Thinner CCT (odds ratio 0.985 associated with each 1 μm increase in CCT), higher presenting IOP (odds ratio 1.131 associated with each 1 mmHg increase in IOP) and increasing age (odds ratio 1.062 associated with each 1 year increase in age) were found to be associated with progression to POAG. Conclusion Patients with a CCT of 579 μm or more, a presenting intraocular pressure of 26 mmHg or less and age 75 years or less had a lower risk of developing POAG within this cohort of patients.

The Influence of Age and Intraocular Pressure on the Optic Cup in a Normal Population

To determine the effects of age and intraocular pressure (IOP) on optic cup and neural rim size, and cup-disc ratio in a well defined population free from apparent glaucoma and other optic nerve disease. Data were collected on 3654 people, 49 years or older, living in the Blue Mountains, west of Sydney. Examination included subjective refraction and Zeiss colour stereo (Carl Zeiss, Oberkochen, Germany) optic disc photographs. Magnification effects of the eye and camera were corrected. After excluding subjects with optic nerve diseases, data from 6579 normal phakic eyes of 3358 subject (91.9% of those examined) were used. Adjusted for optic disc size and IOP, cup diameter increased 0.01 mm, cup-disc ratio increased 0.01, and neural rim width decreased 0.01 mm for every decade of age increase. Adjusted for age and optic disc size, cup diameter increased 0.01 mm, cup-disc ratio increased 0.04, and neural rim width decreased 0.07 mm for every 10 mmHg increase in IOP. The IOP-related increase in cup-disc ratio amounted to 9.5% of the mean per 10 mmHg, while the age related increase was 1.9% of the mean. These data support the hypothesis that there is an age-related loss of tissue from the neuroretinal rim. However the mean change between the ages of 50 and 90 years is very small. The association between increasing IOP and smaller neural rim width could suggest a causal relationship. However, it is also plausible that IOP and optic cup size are both determined by other unmeasured factors.