Ocular Pulse Amplitude in Patients with Asymmetric Primary Open-Angle Glaucoma

The Pascal dynamic contour tonometer (DCT) allows measurement of intraocular pressure (IOP) independently of corneal properties. It records, simultaneously, haemodynamic IOP fluctuations and the difference between the systolic and the diastolic IOP corresponding to the ocular pulse amplitude (OPA). The OPA indirectly reflects choroidal perfusion and could be considered as an independent risk factor in glaucoma. We aimed to establish the physiological diurnal variability of the OPA and its correlations with other biophysical parameters because its characteristics remain partly unclear. Prospective study including 52 eyes of 28 normal subjects with Goldmann applanation tonometry (GAT) IOPs < 22 mmHg. Subjects treated with systemic medications that could interfere with blood pressure or heart rate were excluded. IOP was measured at 9:00 am, 1:00 pm, and 4:00 pm by GAT and DCT. Two consecutive GAT followed by three consecutive DCT measurements were performed in each session by the same clinician (SP). Only DCT measurements with quality 1 and 2 were taken into account. Blood pressure, pulse rate, and central corneal thickness (CCT) were recorded after the last IOP measurements. Spearman correlation coefficient was used for assessment of correlations. Mean age was 40 +/- 14 years. Mean DCT values were significantly higher than GAT readings (mean = 16.8 +/- 2.0 vs. 15.2 +/- 2.8 mmHg, P < 0.02). The mean OPA was 2.2 +/- 0.7 mmHg (range: 1-3.4 mmHg). The mean amplitude of diurnal OPA fluctuations was 0.4 mmHg. There was no significant difference in the mean OPA values at each time of the diurnal curve. The intraclass correlation (ICC) of only one OPA measurement in relation to part of total variance due to inter-measurement variation was 78%. Averaging over three independent readings of OPA improved ICC to 91%. The OPA was correlated with GAT (r = 0.31, P < 0.0001) and DCT IOP measurements (r = 0.49, P < 0.0001). It was correlated neither with blood pressure nor with age. OPA values of both eyes of the same individual were highly correlated (r = 0.89, P < 0.0001). In normal healthy eyes, the ocular pulse amplitude remains stable during normal outpatient office hours and was not correlated with blood pressure or age of patients.

To observe the diurnal variations of intraocular pressure (IOP) measured with dynamic contour tonometer (DCT) in primary open angle glaucoma (POAG) patients, normal tension glaucoma (NTG) patients, and healthy controls, and to compare the differences of diurnal variation curves between the two eyes of each subject and define the distribution of the peak of IOP; to analyze the diurnal variation range of ocular pulse amplitude (OPA) and compare the differences among the POAG and NTG patients and healthy controls. DCT was used to measure the diurnal variations of IOP and OPA in the two eyes of 18 POAG patients, 17 NTG patients and 30 normal controls at 5:00, 7:00, 10:00, 14:00, 18:00, and 22:00 and the distribution of the peak IOP was observed. The range of the diurnal variation of OPA was identified. The diurnal variation curves of IOP were different among the POAG patients, NTG patients, and normal people, and also between the two eyes of each subject. Four right eyes (13.3%) and 6 left eyes (20.0%) of the healthy controls, 4 right eyes (23.5%) and 5 left eyes (29.4%) of the NTG patients, and 5 right eyes (27.8%) and 4 left eyes (22.2%) of the POAG patients reached the peak IOP values in out-office period. Diurnal variation of OPA was detected in both the patients and controls, and the variation curves were different within different groups sampled and between the two eyes of each subject. The diurnal OPA range of the right and left eyes of the POAG group were (2.1 +/- 1.3) mm Hg, and (2.4 +/- 1.9) mm Hg respectively, significantly larger than those of the normal controls [(1.1 +/- 0.5) mm Hg and 1.2 +/- 0.5) mm Hg respectively], and those of the NTG group [(1.1 +/- 0.8) mm Hg and (1.0 +/- 0.5) mm Hg) respectively] (all P < 0.01). OPA has diurnal variation. The diurnal variation of the POAG patients is the largest. NTG patients and normal controls have asymmetric IOP and OPA diurnal variations. The two eyes of the same individual cannot always be treated as the same. The value of IOP measured in the office-time cannot completely represents the 1 d IOP.

The purpose of this study was to develop a method of estimating pulsatile ocular blood volume (POBV) from measurements taken during an ophthalmic exam, including axial length and using a tonometer capable of measuring intraocular pressure (IOP) and ocular pulse amplitude (OPA). Unpublished OPA data from a previous invasive study was used in the derivation, along with central corneal thickness (CCT) and axial length (AL), as well as IOP from the PASCAL dynamic contour tonometer (DCT) and intracameral (ICM) measurements of IOP for 60 cataract patients. Intracameral mean pressure was set to 15, 20, and 35 mmHg (randomized sequence) in the supine position, using a fluid-filled manometer. IOP and OPA measurements were acquired at each manometric setpoint (DCT and ICM simultaneously). In the current study, ocular rigidity (OR) was estimated using a published significant relationship of OR to the natural log of AL in which OR was invasively measured through fluid injection. Friedenwald’s original pressure volume relationship was then used to derive the estimated POBV, delivered to the choroid with each heartbeat as a function of OR, systolic IOP (IOPsys), diastolic IOP (IOPdia), and OPA, according to the derived equation POBV = log (IOPsys/IOPdia) / OR. Linear regression analyses were performed comparing OPA to OR and calculated POBV at each of the three manometric setpoints. POBV was also compared to OPA/IOPdia with all data points combined. Significance threshold was p < 0.05. OR estimated from AL showed a significant positive relationship to OPA for both DCT (p < 0.011) and ICM (p < 0.006) at all three manometric pressure setpoints, with a greater slope for lower IOP. Calculated POBV also showed a significant positive relationship to OPA (p < 0.001) at all three setpoints with greater slope at lower IOP, and a significant negative relationship with IOPdia. In the combined analysis, POBV showed a significant positive relationship to OPA/ IOPdia (p < 0.001) in both ICM and DCT measurements with R2 = 0.9685, and R2 = 0.9589, respectively. POBV provides a straight-forward, clinically applicable method to estimate ocular blood supply noninvasively. Higher IOP in combination with lower OPA results in the lowest values of POBV. The simplified ratio, OPA/ IOPdia, may also provide a useful clinical tool for evaluating changes in ocular blood supply in diseases with a vascular component, such as diabetic retinopathy and normal tension glaucoma. Future studies are warranted.

Purpose: The dynamic contour tonometer (DCT) is designed to measure the IOP independently of the corneal properties. It is foreseen of a digital LCD screen which displays the IOP, the OPA and the quality score (Q) of measurements varying from 1 (excellent) to 5 (poor). The manufacturer recommends discarding the IOP and OPA values with Q4 and 5. The aim of our study was to assess if IOP and OPA measurements with Q3 are acceptable for clinical and research purposes. Methods: 2 consecutive GAT IOP measurements were followed after 10 minutes break by 3 consecutive DCT IOP measurements in 210 patients. Only 85 patients who had IOP and OPA values with Q score 1, 2 and 3 were included in this sub‐study.The mean DCT IOP and OPA were taken for the statistical analyzes. DCT IOP Q3 was separately compared with Q2 and Q1 values. DCT IOP Q1 and Q2 were compared as well. The same comparison was performed for OPA. The Pearson correlation was used for correlation assessment. Results: The mean age was 56±14 years. The mean IOP with GAT was 18.2±4.4 mmHg. The mean IOP Q3, Q2 and Q1 were respectively 17.8±3.3, 17.5±3.3 and 17.5±3.4 mmHg. The mean OPA Q3, Q2 and Q1 were respectively 2.5±1.0, 2.5±1.0 and 2.5±0.9 mmHg.The Pearson correlation for DCT IOP Q3‐2, DCT IOP Q3‐1 and DCT IOP Q2‐1 were equal to 0.9 (r= 0.28, p&lt;0.01).The Pearson correlation for OPA Q3‐2 was: 0.8, for OPA Q3‐1: 0.7 and for OPA Q2‐1: 0.8. The difference between these value were not statistically significant. Conclusions: The IOP and the OPA values with Q 1, 2 or 3 measured by DCT are not significantly different and can be taken into account for clinical and research purposes.

Pseudoexfoliation syndrome (PEX) is a relatively widespread generalized age-related disease, in which abnormal fibrillar extracellular material is produced and accumulates in many tissues. It seems reasonable to evaluate ocular pulse amplitude in patients with PEX. Purpose. To evaluate ocular pulse amplitude in patients with PEX. Methods. 460 eyes of 230 patients were enrolled in the prospective study. We evaluated ocular pulse amplitude and perfusion pressure. Results. Difference in perfusion pressure between groups was not significant. Ocular pulse amplitude was significantly lower in patients with PEX. Conclusion. Ocular pulse amplitude decrease indicates damage of ocular blood flow.

To evaluate the correlation between intraocular pressure (IOP) rise, ocular pulse amplitude (OPA), and choroidal thickness (ChT) during the water drinking test (WDT). Primary open-angle glaucoma (POAG) patients were submitted to the WDT followed by serial IOP measurements using dynamic contour tonometry (DCT), Goldman tonometry (GAT), and ChT measurements using ultrasonographic A and B-scan (USG). A control group not submitted to the test was also evaluated using DCT, GAT, and USG. Intraclass correlation coefficient (ICC) was calculated in the control group in order to assess the reproducibility of measurements. Spearman's coefficient (rho) was used to assess the correlation between the variables. Thirty eyes were included in the study. There was a significant IOP rise during the WDT using both GAT and DCT (p < 0.001). The OPA and ChT measurements also increased significantly (p < 0.001). Spearman's correlation between the OPA values and ChT measurements was significant and moderate (rho = 0.40, p = 0.005). The average increase of OPA and ChT measurements occurred 15 min before the IOP rise. There was a significant increase of OPA and ChT measurements followed by an IOP rise during the WDT. Increased choroidal volume due to hemodynamic forces may be enrolled in the mechanism of IOP elevation during this stress test.

Objective To investigate the effects of body mass index (BMI) on intraoeular pressure (IOP) and ocular pulse amplitude (OPA).Methods Totally 60 healthy individuals who came to our hospital for health examination without any systemic diseases were included in the study on June 3,2013.BMI (kg/m2) was calculated for every individual.IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT).Blood pressure was also measured along with the DCT.The patients were divided into three groups according to BMI,Group 1,BMI＜25kg/m2; Group 2,25kg/m2≤BMI＜30kg/m2; Group 3,BMI≥30kg/m2.Mean values of IOP,OPA,systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.Results There were no statistically significant difference between groups in terms of IOR SBP and DBP,while OPA values had statistically significant difference between groups,and there was significantly lower in group3.Conclusions Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow. Key words: Body mass index; Intraocular pressure; Ocular pulse amplitude; Obesity

Pediatric celiac disease (CeD) and type 1 diabetes mellitus (T1DM) have well established effects on eye health but comorbid effect is not known. To evaluate the eye health of children with T1DM and CeD to predict microvascular retinal pathologies by diagnosis of probable intraocular pressure increase which is an important glaucoma trigger. In this case-controlled study, 28 eyes of 14 children both T1DM and CeD, with a mean age of 12.6 ± 3.9 years, and 28 eyes of gender-matched 14 healthy children as a control group were included. In both groups, detailed ocular examinations and measurement of intraocular pressure (IOP), ocular pulse amplitude (OPA), thicknesses of ganglion cell layer (GCL), inner plexiform layer (IPL), retinal nerve fiber layer (RNFL), and choroid thicknesses (CT) were done. All the patients with T1DM and CeD were newly diagnosed. The evaluations of IOP and OPA were made using a Pascal dynamic tonometer and thicknesses measured by optical coherence tomography. The IOP and OPA values of the patient group were found to be statistically significantly higher than those of the control group (17.1 and 1.86 vs 14.78 and 1.57 mmHg, P <.0001, P <.001, respectively). IOP values of all patients were higher than IOP cut off levels for diagnosis of hypertension. CT was significantly thinner in the patient group than in the control group (385.4 μm vs 331.71 μm, respectively, P < 0.03). No significant difference was found between the groups in respect of GCL, IPL, and RNFL values. The higher IOP and OPA values of the children with T1DM and CeD were considered to be the result of the microvascular pathologies in T1DM and increased inflammation associated with CeD. High IOP and OPA values can lead to damage in the eye as intraocular blood flow and choroidal perfusion are affected. In order to prevent these eye problems, measurement of IOP and OPA should be done in children with diagnosis of T1DM and CeD and also follow up studies needed.

To evaluate a novel contact lens-embedded pressure sensor for continuous measurement of intraocular pressure (IOP). Repeated measurements of IOP and ocular pulse amplitude (OPA) were recorded in 12 eyes of 12 subjects in sitting and supine positions using 3 configurations of the dynamic contour tonometer: slit-lamp mounted (DCT), hand-held (HH), and contact lens-embedded sensor (CL). The IOP and OPA for each condition were compared using repeated measures ANOVA and the 95% limits of agreement were calculated. The sitting IOP (mean and 95% CI) for each configuration was DCT: 16.3 mm Hg (15.6 to 17.1 mm Hg), HH: 16.6 mm Hg (15.6 to 17.6 mm Hg), and CL: 15.7 mm Hg (15 to 16.3 mm Hg). The sitting OPA for each configuration was DCT: 2.4 mm Hg (2.1 to 2.6 mm Hg), HH: 2.4 mm Hg (2.1 to 2.7 mm Hg), and CL: 2.1 mm Hg (1.8 to 2.3 mm Hg). Supine IOP and OPA measurements with the CL and HH sensors were both greater than their corresponding sitting measurements, but were significantly less with the CL sensor than the HH sensor. The mean difference and 95% Limits of Agreement were smallest for the DCT and CL sensor comparisons (0.7+/-3.9 mm Hg) and widest for the CL and HH sensors (-1.9+/-7.25 mm Hg); these wider limits were attributed to greater HH measurement variability. The CL sensor was comparable to HH and DCT sensors with sitting subjects and is a viable method for measuring IOP and OPA. Supine measurements of IOP and OPA were greater than sitting conditions and were comparatively lower with the CL sensor. HH measurements were more variable than CL measurements and this influenced the Limits of Agreement for both sitting and supine conditions.

To determine if the difference in intraocular pressure (IOP) measurements between dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) is correlated with axial length (AL), and to assess the possible influence of age, sex, central corneal thickness (CCT), corneal hysteresis (CH), ocular pulse amplitude (OPA), and glaucoma status on the difference in IOP measurements between the 2 instruments (ΔIOP=DCTIOP- GATIOP). Two hundred sixty-oneparticipants (509 eyes) in these 4 groups were included: 53 normal individuals (N; 106 eyes), 112 glaucoma patients (OAG; 212 eyes), 52 glaucoma suspects (GS; 103 eyes), and 44 patients with ocular hypertension (OHT; 88 eyes). The patients who had had an incisional ocular surgery were excluded. All participants underwent IOP evaluation with DCT and GAT and AL, CCT, and CH measurements. The influence of age, sex, AL, CCT, CH, OPA, and glaucoma diagnostic status on ΔIOP was evaluated using correlation analysis and analysis of variance (ANOVA). Right (OD) and left eyes (OS) were analyzed separately. ΔIOP was higher in eyes with longer axial lengths (OD: r=0.142, P=0.02; OS: r=0.233, P<0.001). ΔIOP also correlated with CH (OD: r=-0. 127, P=0.04; OS: r=-0.169, P=0.01), in which the ΔIOP increased as CH decreased (corresponding to less rigid corneas). OPA also correlated negatively with ΔIOP, but the correlation was only statistically significant in left eye (OD: r=-0.112, P=0.08; OS: r=-0.124, P=0.05). Age, CCT, sex, and diagnostic status did not influence ΔIOP significantly. GAT underestimated IOP more compared with DCT in patients with longer axial length and in patients with lower corneal hysteresis.

Effect of Corneal Thickness on Dynamic Contour, Rebound, and Goldmann Tonometry

BackgroundThe purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP).Material/MethodsThis study included 140 eyes of 70 subjects – 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant.ResultsThe following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=–0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL.Conclusions(1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP.

Purpose The aim of this study was to compared the effect of cataract extraction by phacoemulsification and posterior chamber lens implantation on measured intraocular pressure (IOP) using the Goldmann applanation tonometer, the Pascal dynamic contour tonometer (DCT), the Goldmann applanation tonometer (GT) and pneumotonometer (PT)Methods 97 eyes were measured in the operated eye one day before and one day, one week and one month after cataract surgery with the three tonometers, the IOP, ocular pulse amplitude (OPA),and central corneal thickness (CCT)Results Corneal edema induced by phacoemulsification cataract surgery resulted in statistically significant increases in CCT (87,8 μm SD 56,8 ;p&lt; 0,001), Pascal DCT IOP (4,8 mmHg, SD 8,0; p&lt; 0,001),Goldmann IOP (1,4 mmHg, SD 5,1;p&lt;0,015) and OPA (0,9 mmHg, SD 3,5; p&lt; 0,025) but not in pneumotonometry IOP (1,1mmHg, SD 5,3; p=0,065). Changes in IOP measured by GT and PT were less than those measured by the Pascal DCT. The variation between the Pascal DCT (Rho 0,247; p=0,038), and Pneumotonometer (Rho 0,358; p=0,002) was strongly correlated to the change in CCTConclusion Corneal edema after phacoemulsification cataract surgery increased IOP readings in the three tonometer compared, this increment is bigger in Pascal DCT readings. Changes in CCT are statistically significant associated with increased Pascal DCT IOP readings. Change in corneal biomechanics may in part be responsible for increased in the measured of IOP with Pascal DCT and GT

BackgroundThe purpose of this study was to investigate the correlation between ocular perfusion pressure and ocular pulse amplitude in glaucoma, ocular hypertension, and normal eyes.MethodsNinety eyes from 90 patients were included. Thirty patients had been recently diagnosed with glaucoma and had no previous history of treatment for ocular hypotension, 30 had elevated intraocular pressure (IOP) without evidence of glaucoma, and 30 had normal IOP (<21 mmHg) with no detectable glaucomatous damage. Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), blood pressure measurement, pachymetry, Humphrey visual field, and routine ophthalmic examination was performed in each patient. Ocular perfusion pressure was calculated as the difference between mean arterial pressure and IOP. The ocular pulse amplitude was given by DCT. The Pearson correlation coefficient was used to compare the glaucomatous and ocular hypertensive groups, and comparisons with the normal IOP group were done using the Spearman’s rank correlation coefficient.ResultsMean IOP by DCT was 22.7 ± 4.3 mmHg in the glaucoma group, 22.3 ± 2.8 mmHg in the ocular hypertension group, and 14.3 ± 1.6 mmHg in the control group. Mean IOP by GAT was 19.0 ± 5.1 mmHg for glaucoma, 22.4 ± 2.1 mmHg for ocular hypertension, and 12.9 ± 2.2 mmHg for controls. Mean ocular pulse amplitude was 3.4 ± 1.2 mmHg in the glaucoma group, 3.5 ± 1.2 mmHg in the ocular hypertension group, and 2.6 ± 0.9 mmHg in the control group. Mean ocular perfusion pressure was 46.3 ± 7.9 mmHg in the glaucoma group, 46.3 ± 7.9 mmHg in the ocular hypertension group, and 50.2 ± 7.0 mmHg in controls. No significant correlation between ocular perfusion pressure and ocular pulse amplitude was found in any of the groups (P = 0.865 and r = −0.032, P = 0.403 and r = −0.156, P = 0.082 and ρ = −0.307 for glaucoma, ocular hypertension, and normal eyes, respectively).ConclusionThere is no significant correlation between ocular perfusion pressure and ocular pulse amplitude values in glaucoma, ocular hypertension, or normal eyes. IOP values measured by GAT correlate with those measured by DCT.

PurposeTo evaluate the effect of intravitreal (IVT) bevacizumab in neovascular age-related macular degeneration (AMD) on global choroidal hemodynamics, as measured by ocular pulse amplitude (OPA).MethodsThis was a two-center prospective study (Sheba Medical Center, Israel, and University Hospitals Leuven, Belgium). AMD patients who required IVT bevacizumab (1.25 mg/0.05 mL; first or repeated) were examined three times: at days 0 (prior to injection), 7 (±3), and 28 (±7) postinjection. At each visit, OPAs of both eyes were measured using the Pascal dynamic contour tonometer (DCT). A paired t-test between preoperative and postoperative OPA was conducted. Pearson correlation was used to evaluate the influence of various measured parameters on DCT–OPA.ResultsA total of 38 neovascular AMD patients were recruited, and 30 patients were included in the final analysis (18 females and 12 males; age 78.8 ± 5.82 years [mean ± standard deviation]). A good correlation was found throughout the study between the DCT–intraocular pressure (IOP) and Goldmann IOP and between DCT–IOP and DCT–OPA. No change in OPA of bevacizumab-treated eyes was found between the visits (2.24 ± 0.73, 2.2 ± 0.86, and 2.23 ± 0.73 mm Hg at visits 1, 2, and 3, respectively; paired t-test: P = 0.77 between visits 1 and 2, P = 0.98 between visits 1 and 3). No correlations were found between DCT–OPA and age, heart rate, systemic blood pressure, axial length, keratometry readings, and central corneal thickness.ConclusionsOPA, an indirect measure of global choroidal hemodynamics, remains unchanged following IVT off-label bevacizumab. This finding adds to the growing evidence regarding the safety profile of bevacizumab in AMD treatment.