Pascal Dynamic Contour Tonometer Research Articles

Estimating pulsatile ocular blood volume from intraocular pressure, ocular pulse amplitude, and axial length.

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 Unpublished OPA data from a previous invasive study was used in the derivation, along with central corneal thickness (CCT) and axial length (AL), as well as IOP from the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.

Innovative approaches to measuring intraocular pressure

AbstractAlthough different factors have been implicated in the development and progression of glaucoma, intraocular pressure (IOP) remains the main modifiable risk factor. Goldmann applanation tonometer (GAT) considers the “gold standard” for measuring IOP. The main deficiency of GAT, however, is the static nature of its measurements and that it is dependent on corneal biomechanics, central corneal thickness as well as scleral stiffness. The single measurement of IOP for the management of glaucoma provides limited information since it does not take into account the natural fluctuation of IOP, individual ranges, IOP peaks or variations throughout the day. Although the role of IOP fluctuations in glaucoma progression is not clearly defined, there is consensus on the importance of understanding the circadian profiles of IOP in glaucoma patients. Given the limitations of GAT for the actual measurement of IOP, different tonometers have been designed with the aim of advancing in self‐tonometry as Icare HOME, or obtaining independent measurements of corneal biomechanics, as Ocular Response Analyser (ORA), Pascal dynamic contour tonometer or the Corvis ST tonometer. Research to monitor IOP is based on three different strategies: (1) self‐tonometry; (2) permanent monitoring of the IOP; and (3) the temporary monitoring of the IOP. Currently, the sensors in contact lenses allow the IOP profiles to be recorded semi‐continuously for 24 hours with a minimally invasive technique, independent of the patient's position and the activity performed, opening new perspectives in the knowledge and management of glaucoma.

Effects of childhood obesity on ocular pulse amplitude and intraocular pressure.

To assess intraocular pressure and ocular pulse amplitude changes in obese children and adolescents using dynamic contour tonometry. 137 cases, 64 obese and 73 healthy children, who were both age-matched and gender-matched, comprised the study population in this cross-sectional study. Children with body mass index values >95% for sex and age were regarded as obese. Participants underwent detailed ophthalmological examinations, including intraocular pressure measurement using a Pascal dynamic contour tonometer. Relationships between intraocular pressure and ocular pulse amplitude measurements and age, sex, obesity, pubertal status, and insulin resistance were investigated. Bilateral ocular pulse amplitude was lower while intraocular pressure was higher in the obese group than in the control group (p<0.001). No significant relationship was observed between insulin resistance and intraocular pressure or ocular pulse amplitude (p>0.005). No correlation was determined between systolic and diastolic blood pressure, homeostasis model assessment for insulin resistance, or blood lipid levels and intraocular pressure and ocular pulse amplitude. Our results show that obesity caused an increase in intraocular pressure and a decrease in ocular pulse amplitude independently of insulin resistance in children and adolescents. Prospective studies involving long-term follow-up of cases are now needed to assess the probable adverse effects of these ocular findings in obese children.

Association of obstructive sleep apnea/hypopnea syndrome with glaucomatous optic neuropathy and ocular blood flow.

The present study aimed to investigate the prevalence of glaucomatous optic neuropathy in patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). In total, 83 subjects (45 cases of severe OSAHS and 38 controls) underwent polysomnographic assessment and were evaluated for the severity of the disease using the Apnea-Hypopnea index. A detailed ophthalmologic exam was then performed, including measurement of the intraocular pressure (IOP) with a Goldmann applanation tonometer and Pascal dynamic contour tonometer (DCT), recording of the ocular pulse amplitude measured by the Pascal DCT, standard automated perimetry and retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness evaluation using optical coherence tomography. Ocular blood flow was assessed using color Doppler imaging (CDI) and ophthalmic artery indices were evaluated, including peak systolic blood velocity, end diastolic blood velocity and resistivity index (RI). There was a significant difference in the mean IOP between controls (11.03±3.85 mmHg) and cases of severe OSAHS (18.06±3.39 mmHg) when the IOP was measured by DCT (P<0.0001), but not with the Goldmann applanation tonometer (IOP, 13.97±2.85 mmHg for controls and 14.89±3.21 mmHg for cases of severe OSAHS; P=0.0877). Significant negative correlations were observed between RNFL thickness and RI (P=0.0011) in cases of severe OSAHS, as well as between GCC thickness and RI (P<0.008) in all subjects. Furthermore, a negative correlation between RI and RNFL thickness in severe cases of OSAHS suggested a hemodynamically induced vulnerability of RNFL in OSAHS. The correlation between RI and GCC thickness in all subjects suggested that impaired perfusion, more prominent in OSAHS, leads to structural changes. Therefore, cases of severe OSAHS should be monitored for changes in RNFL and GCC thickness, as well as CDI findings. Furthermore, patients with increased ophthalmic artery RIs should be monitored for changes in the GCC, regardless of the etiology of the RI increase.

Heartbeat-Induced Corneal Axial Displacement and Strain Measured by High Frequency Ultrasound Elastography in Human Volunteers.

PurposeThe purpose of this study was to establish in vivo data acquisition and processing protocols for repeatable measurements of heartbeat-induced corneal displacements and strains in human eyes, using a high-frequency ultrasound elastography method, termed ocular pulse elastography (OPE).MethodsTwenty-four volunteers with no known ocular diseases were recruited for this study. Intraocular pressure (IOP) and ocular pulse amplitude (OPA) were measured using a PASCAL Dynamic Contour Tonometer (DCT). An in vivo OPE protocol was developed to measure heartbeat-induced corneal displacements. Videos of the central 5.7 mm of the cornea were acquired using a 50-MHz ultrasound probe at 128 frames per second. The radiofrequency data of 1000 frames were analyzed using an ultrasound speckle tracking algorithm to calculate corneal displacements and quantify spectral and temporal characteristics. The intrasession and intersession repeatability of OPE- and DCT-measured parameters were also analyzed.ResultsThe in vivo OPE protocol and setup were successful in tracking heartbeat-induced corneal motion using high-frequency ultrasound. Corneal axial displacements showed a strong cardiac rhythm, with good intrasession and intersession repeatability, and high interocular symmetry. Corneal strain was calculated in two eyes of two subjects, showing substantially different responses.ConclusionsWe demonstrated the feasibility of high-frequency ultrasound elastography for noninvasive in vivo measurement of the cornea's biomechanical responses to the intrinsic ocular pulse. The high intrasession and intersession repeatability suggested a robust implementation of this technique to the in vivo setting.Translational RelevanceOPE may offer a useful tool for clinical biomechanical evaluation of the cornea by quantifying its response to the intrinsic pulsation.

Ganglion cell layer thickening in patients suffering from Obstructive Sleep Apnea-Hypopnea syndrome with long Mean Apnea-Hypopnea Duration during sleep.

To study the effects of mean apnea-hypopnea duration (MAD), a useful indicator of blood oxygenation, on peripapillary retinal nerve fiber layer (RNFL), macular ganglioncell toinner plexiform layer (GC-IPL) and macular retinal thickness in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Sixty-five patients recently diagnosed with OSAHS and 35 healthy individuals were enrolled in this cross-sectional study. OSAHS patients were divided according to their MAD values into group 1 with 16 participants (MAD:10-15.5s), group 2 with 17 participants (MAD:15.5-19s), group 3 with 17 participants (MAD:19-30s) and group 4 with 15 participants (MAD > 30s). The average and sectorial values of RNFL, GC-IPL and retinal thickness were measured by SS-OCT (DRI OCT Triton, Topcon). Intraocular pressure was recorded by Goldmann Applanation and Pascal Dynamic Contour Tonometer (DCT-IOP). The average RNFL and retinal thicknessvalues were higher in group 4, but did not reach statistical significance. With the exception of the central 1mm at the fovea, GC-IPL was always thickened in group 4, and significant differences were evident when its average value was compared with group 2 (p = 0.03), its superior and inferior-nasal values were compared with group 2 (p = 0.02,p = 0.006,respectively) and group 3 (p = 0.01, p = 0.02,respectively), its superior-temporal value was compared with group 3 (p = 0.003) and the control group (p = 0.03), and its superior-nasal value was compared with group 2 (p = 0.03), group 3 (p = 0.001) and the control group (p = 0.03). DCT-IOP was significantly positively correlated with the duration of sleepin whichoxygen saturation(SaO2 ) was decreased under90% (r = 0.359, p = 0.01). We report a novel observation of GC-IPL thickening in OSAHS patients experiencing long MAD, a parameter which incorporates the severity of breathing events during sleep. Higher DCT-IOP was noted with advancing hypoxemia.

Variations of Intraocular Pressure Measured by Goldmann Applanation Tonometer, Tono-Pen, iCare Rebound Tonometer, and Pascal Dynamic Contour Tonometer in Patients With Corneal Edema After Phacoemulsification.

Edematous corneas had lower Goldmann applanation tonometer (GAT) intraocular pressure (IOP) compared with other tonometers. A significant, mild negative correlation between central corneal thickness (CCT) and GAT IOP was found in a group of significant edematous corneas with CCT increases of >100 µm. To compare the IOP that was randomly obtained with the GAT, Tono-Pen, iCare, and Pascal dynamic contour tonometer in patients with corneal edema after phacoemulsification. Corneal edema was quantified by CCT measurement. The agreement between IOP measurements assessed by different instruments was evaluated using Bland-Altman plots. The relationship between CCT and IOP was investigated using the coefficient of correlation. The CCT and IOP were compared between the periods of postsurgical edema and after its resolution. The mean age of 60 patients was 75.9±7.8 years. CCT increased significantly after surgery, by an average of 96.1±39.9 µm (P<0.001). Relative to the IOPs measured with the GAT in edematous eyes: the mean difference in Tono-Pen IOPs was 4.7 mm Hg; 95% limits of agreement (LOA), -0.3 to 9.6 mm Hg. For iCare, was 2.3 mm Hg; 95% LOA, -2.2 to 6.8 mm Hg. For Pascal dynamic contour tonometer, was 3.0 mm Hg; 95% LOA, -0.4 to 6.5 mm Hg. Edematous corneas had significantly lower GAT IOP than Tono-Pen IOP; 12.3±3.2 versus 16.9±3.1 (P=0.02). Pearson correlation coefficients (r) showed a high correlation between the 4 tonometers in eyes without edema. There was a significant, mild negative correlation between CCT and GAT IOP (r=-0.25, P=0.02) in a group of significant edematous corneas with CCT increases of >100 µm: GAT IOP decreased by 3.1 mm Hg for every 10-µm increase in CCT. IOP readings with GAT tended to be lower than those obtained with the other tonometers, especially the Tono-Pen. GAT IOP readings in cases of severe corneal edema should be interpreted with caution.

The Effects of Surgical Treatment on Retina-Choroidal Findings in Patients With Obstructive Sleep Apnea Syndrome

The purpose of this study was to determine the effect of surgical treatment on ocular findings in obstructive sleep apnea syndrome (OSAS). The authors studied 34 eyes of 34 newly diagnosed OSAS patients. The sleep study was performed before and 6 months after expansion sphincter pharyngoplasty (ESP). Retinal nerve fiber layer (RNFL), choroidal thickness (CT), and retinal arteriolar caliber (RAC) analyses were performed using spectral-domain optical coherence tomography. Intraocular pressure (IOP) and ocular pulse amplitude were performed using the Pascal dynamic contour tonometer. The preoperative and postoperative Apnea Hypopnea Index scores and average oxygen saturation values were significantly different (P = .0001 and P = .001, respectively). There was no significant difference between the preoperative and postoperative RNFL thicknesses (P > .05). The preoperative subfoveal, nasal, temporal CT, and IOP were significantly different from the postoperative measurements (P = .006, P = .05, P = .036, and P = .0001, respectively). ESP had a significant influence on CT and IOP in patients with OSAS, maintaining a decrease in CT and IOP 6 months after surgery. The determination of these ocular findings may be useful to show the positive effects of ESP. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:35-42.].

Impact of corneal parameters on intraocular pressure measurements in different tonometry methods

To evaluate the impact of central corneal thickness (CCT) and corneal curvature on intraocular pressure (IOP) measurements performed by three different tonometers. IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer (GAT), Pascal dynamic contour tonometer (DCT), and ICare rebound tonometer (RT). CCT and corneal curvature were assessed. In healthy eyes, DCT presents significantly higher values of IOP than GAT (17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT (13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 µm and 0.99 mm Hg higher results in eyes with CCT≥600 µm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 µm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 µm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values (R=0.369, P=0.005). The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT; thus, CCT should be taken into consideration for both diagnostics and monitoring.

Evaluation of ocular pulse amplitude in patients with carotid artery stenosis using the Pascal dynamic contour tonometer

BackgroundTo evaluate ocular pulse amplitude (OPA) in patients with carotid artery stenosis (CAS) using the Pascal dynamic contour tonometer (DCT).MethodsConsecutive patients who underwent ultrasound Doppler examination of the carotid artery for the suspicion of CAS were prospectively enrolled in the study. Each patient underwent a complete ocular examination. OPA was measured using Pascal DCT. The participants were divided into four groups according to the degree of CAS: Group 1 (no occlusion, control group), Group 2 (mild occlusion: < 50 per cent), Group 3 (moderate occlusion: 50–69 per cent), and Group 4 (severe occlusion: ≥ 70 per cent).ResultsA total of 161 eyes of 81 patients were included in the study. Of the 81 patients, 50 (61.7 per cent) were male, and 31 (38.3 per cent) were female. The mean age was 66.6 ± 12.3-years (range, 20–91-years). Mean OPA values were found to be 2.68 ± 0.97-mmHg in Group 1 (n = 64 eyes), 2.62 ± 0.83-mmHg in Group 2 (n = 49 eyes), 2.30 ± 0.97-mmHg in Group 3 (n = 27 eyes) and 1.66 ± 0.59-mmHg in Group 4 (n = 21 eyes). There was no statistically significant difference in mean OPA levels between Group 1 and Group 2 (p = 0.73). However, statistically significant differences were found between the other groups when they were compared with each other (Groups 1 and 3, p = 0.02; Groups 1 and 4, p < 0.001; Groups 2 and 3, p = 0.02; Groups 2 and 4, p < 0.001; Groups 3 and 4, p = 0.002).ConclusionOPA decreases in patients with moderate to severe CAS. OPA measurement with Pascal DCT can be used as a screening test for CAS.

The effect of bariatric surgery on intraocular pressure.

Study purpose was to investigate the effects of bariatric surgery on intraocular pressure (IOP) and other ophthalmic parameters in a prospective observational follow-up study. Ophthalmic examination was performed on 22 obese women before and 6months after bariatric surgery. A control group of 15 non-obese age-matched women were studied twice 6months apart. IOP was measured with the Goldmann applanation tonometer (GAT) and the Pascal dynamic contour tonometer (PDCT). None of the subjects had glaucoma. Average weight loss 6months after bariatric surgery was 25±8kg, (p<0.05). Visual acuity (VA), pachymetry and systolic as well as diastolic blood pressures did not differ between the obese and control groups and no change between the visits was detected. At baseline, IOP was significantly higher in theobese group than in the controls (16.6±3.0mmHg GAT and 18.1± 2.2mmHg PDCT compared with 14.3±1.5mmHg GAT and 16.5± 1.9mmHg PDCT respectively). After bariatric surgery, IOP was significantly lower (15.2±2.7mmHg GAT and 16.5±2.0mmHg PDCT, p<0.05) and no significant difference was detected between the operated and control groups. In the whole data at baseline, IOP correlated with weight, body mass index, waist circumference, body fat per cent and systolic blood pressure values. Intraocular pressure (IOP) is significantly higher in obese women than in non-obese age-matched controls. Obese subjects had a decrease in IOP after bariatric surgery with no change in IOP in the control group. This change in obese group may be related to weight loss. Different measures of obesity correlated with IOP at baseline.

Tonometry after Intrastromal Corneal Ring Segments for Keratoconus.

Reliable intraocular pressure (IOP) measurement after intrastromal corneal ring segments (ICRS) implantation is a challenge because of altered corneal morphology. In this study, IOP is measured with four tonometers, compared with Goldmann applanation tonometry (GAT) values and the influence of corneal parameters is established. This study compares IOP measurements made using different tonometers in patients implanted with ICRS and assesses the effects of central corneal thickness (CCT), corneal curvature, and corneal astigmatism on the IOP measurements obtained. In this cross-sectional study, IOP was measured using three different tonometers in 91 eyes of 91 patients with corneal ectasia implanted at least 6 months previously with ICRS. The tonometers tested were the TonoPen XL, Pascal dynamic contour tonometer (DCT), and iCare Pro rebound tonometer. GAT measurements were used as reference. Agreement among the IOPs provided by the different tonometers and the influence of corneal variables on the IOP measurements obtained were assessed using the Bland-Altman method, intraclass correlation coefficients, and multiple linear regression analysis. Mean IOP differences were GAT versus TonoPen XL -0.8 ± 3.07 mm Hg, GAT versus DCT -1.0 ± 3.26 mm Hg, and GAT versus iCare Pro 0.8 ± 2.92 mm Hg. Our multiple linear regression analysis identified CCT as a confounding factor affecting all the tonometer readings but DCT-IOP. In patients fitted with ICRS, IOP measurements made using the iCare Pro and TonoPen XL showed most agreement with GAT. Intraocular pressure measurements made by DCT were unaffected by corneal topographic factors though this procedure slightly overestimated GAT readings.

Measuring Intraocular Pressure in Patients With Keratoconus With and Without Intrastromal Corneal Ring Segments.

To compare intraocular pressure (IOP) measurements made using 5 tonometers in keratoconic eyes with and without intrastromal corneal ring segments. This was an observational case series study. A total of 147 eyes of 147 patients with keratoconus, 74 of which had undergone corneal ring segment placement, were prospectively evaluated. IOP was measured using the tonometers Tonopen XL, Pascal dynamic contour tonometer, iCare Pro, ocular response analyzer (ORA), and Goldmann applanation (GAT) in random order. The Bland-Altman method was used to examine interinstrument agreement. Effects on readings of central corneal thickness, corneal curvature, and corneal astigmatism were assessed by multivariate regression analysis. Smallest mean IOP differences with GAT measurements in eyes without and with ring segments, respectively, were detected for iCare Pro [0.2 (2.9) mm Hg and 0.4 (3.0) mm Hg, P=0.914] and greatest differences for ORA Goldmann-correlated IOP [5.8 (3.3) mm Hg and 6.0 (3.1) mm Hg, P=0.363]. Best agreement with GAT was shown by iCare Pro (ICC=0.829; 95% CI, 0.721-0.896) and worse agreement by ORA corneal-compensated IOP (ICC=-0.145; 95% CI, -0.826 to 0.283). All but the dynamic contour tonometer readings were influenced by central corneal thickness, yet these measurements were affected by the presence of ring segments (P=0.017) and corneal astigmatism (P=0.030). Corneal curvature only affected ORA Goldmann-correlated IOP (P=0.029). All 5 tonometers provided reliable IOP readings in the keratoconic eyes regardless of the presence of corneal ring segments. iCare Pro readings were most consistent with GAT, whereas ORA readings were least consistent with this reference standard.

Effects of Swimming Goggles Wearing on Intraocular Pressure, Ocular Perfusion Pressure, and Ocular Pulse Amplitude.

To evaluate changes in the ocular pulse amplitude (OPA) and ocular perfusion pressure (OPP), and investigate factors associated with intraocular pressure (IOP) elevation due to periorbital compression during swimming goggles (SG) use. This cross-sectional study evaluated 35 eyes of 35 healthy volunteers during the wearing of a drilled SG. OPP calculation, Goldman applanation tonometry, and OPA measurements (using Pascal dynamic contour tonometer) were performed before, during, and after SG use. Scleral rigidity (calculated with Schiotz tonometry readings), orbital rim area, exophthalmometry, spherical equivalent, axial length, corneal thickness, and the goggles' rubber elastic force were considered in the multivariable analysis as potentially related to IOP changes. SG significantly increased IOP after 2 minutes of use (13.34±2.67 vs. 23.46±7.20 mm Hg, P<0.0001). After removal, IOP decreased significantly (10.20±5.85 mm Hg, P<0.0001). A inverse correlation between IOP and OPP differences was observed with the SG wearing (r=-0.57; P=0.0003). Mean OPA was significantly higher during compared with before SG wear (2.57±1.34 vs. 1.82±0.55 mm Hg for the timepoints 2 and 1, respectively; P=0.0064). Only orbital rim area (P=0.0052) and elastic force (P=0.0019) were significantly associated with IOP elevation. SG provoked acute IOP elevation and disturbance in the ocular hemodynamics, which was associated with larger orbital rim area and greater SG elastic force. These findings could have implications for subjects at high risk for glaucoma onset or progression.

Relationship Between Subfoveal Choroidal Thickness, Ocular Pulse Amplitude, and Intraocular Pressure in Healthy Subjects.

To investigate the correlation between subfoveal choroidal thickness (SFCT), ocular pulse amplitude (OPA), and intraocular pressure (IOP) in healthy individuals. In total, 106 eyes of 106 healthy adult participants were included in this cross-sectional study. Spectral-domain optical coherence tomography was used to measure the SFCT. OPA and IOP were measured with the Pascal dynamic contour tonometer. The Pearson correlation test was performed to examine the relationship between SFCT, OPA, and IOP. When age, sex, and body mass index (BMI) were controlled separately, a weak correlation occurred between SFCT and OPA (age controlled, r=0.20; sex controlled, r=0.19; BMI controlled, r=0.13). SFCT and OPA were fairly correlated in older age (r=0.33, P=0.02) and low BMI (r=0.33, P=0.02). SFCT and IOP were not correlated statistically significantly (r=0.05, P=0.59). There is a weak correlation between SFCT and OPA in healthy individuals when age is controlled. The association becomes stronger in participants with low BMI. There is no relation between SFCT and IOP.

Subfoveal Choroidal Thickness Is Associated with Blood Hematocrit Level

Purpose: To compare subfoveal choroidal thickness (SFCT), retinal vessel caliber, and ocular pulse amplitude between treated polycythemia vera (PV) patients and healthy adults. Methods: Forty patients with PV and 40 age- and sex-matched healthy controls were recruited for this cross-sectional study. Spectral-domain optical coherence tomography was used for SFCT and retinal vessel caliber measurements. The Pascal dynamic contour tonometer was used for ocular pulse amplitude measurements. The correlations of blood hematocrit levels with the studied ocular parameters were analyzed. Results: There were no statistically significant differences between the PV patients and controls in SFCT, retinal vessel caliber, and ocular pulse amplitude (p > 0.05). SFCT was associated with hematocrit level in both PV patients and healthy adults (p < 0.05). Conclusions: Although SFCT, retinal vessel caliber, and ocular pulse amplitude parameters are similar in treated PV patients and healthy controls, SFCT is associated with hematocrit level.

Ocular pulse amplitude and retinal vessel caliber changes after intravitreal ranibizumab.

The purpose of the present study was to examine the effects of intravitreal ranibizumab on ocular pulse amplitude (OPA) and retinal vessel caliber (RVC) in wet age-related macular degeneration (AMD). Thirty-two eyes of 32 wet AMD patients were included in this case series. Three consecutive monthly injections of ranibizumab were performed. The OPA was measured with the Pascal dynamic contour tonometer. RVC measurements were taken with spectral-domain optical coherence tomography. Pre-injection mean OPA value was 2.55±0.76mmHg and post-injections mean OPA value was 2.79±0.88mmHg at the last visit (p=0.10). Pre-injection mean arteriole and venule RVC were 96.7±9.4 and 125.9±8.4µm; while post-injections arteriole and venule RVC were 96.0±8.7 and 125.6±8.9µm, respectively (p>0.05). OPA and RVC are unchanged after triple intravitreal ranibizumab injections, indicating that this treatment does not significantly alter gross retina-choroidal vasculature and hemodynamics.

Evaluation of the impact of Nd:YAG laser posterior capsulotomy on ocular pulse amplitude and anterior segment morphology

Posterior capsular opacification (PCO) is the most frequent complication after cataract surgery. The most used method in order to disrupt the opacified posterior capsule is Nd-YAG laser posterior capsulotomy. Our aim was to evaluate the impact of Nd-YAG laser posterior capsulotomy on ocular pulse amplitude (OPA), central corneal thickness (CCT), corneal volume (CV), iridocorneal angle (ICA), and anterior chamber depth (ACD). Thirty-three eyes of 30 pseudophakic patients who underwent Nd-YAG capsulotomy due to posterior capsule opacification, were included in this prospective cross-sectional consecutive case series. The OPA was measured with the Pascal dynamic contour tonometer. The CCT, CV, ICA, and ACD measurements were taken with the Scheimpflug imaging system (Pentacam HR). The examinations were performed preoperatively, and repeated at the postoperative first hour, week, and month. The mean OPA, ICA, and ACD values did not change statistically significantly after the posterior capsulotomy (P > 0.05). The mean CCT increased markedly and the mean CV increased slightly after one hour from the capsulotomy (P = 0.001 and P = 0.02, respectively), and then returned to the baseline values at the first week and first month visits (P > 0.05). Nd:YAG capsulotomy does not significantly alter OPA, ICA, and ACD; but it causes temporary increase of CCT and CV in the short term.

Choroidal changes after cardiopulmonary bypass

Choroid, which is the vascular tissue responsible for blood supply to the outer parts of the retina, might be affected by hemodynamic events. We aimed to reveal choroidal thickness and ocular pulse amplitude changes after cardiopulmonary bypass in which gross hemodynamic alterations occur. Forty-two eyes of 42 patients who underwent heart surgery with cardiopulmonary bypass were examined in this prospective, cross-sectional case series. The spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) was used to analyze sub-foveal choroidal thickness. The ocular pulse amplitude, the surrogate of gross choroidal blood flow, was measured with the Pascal dynamic contour tonometer (Pascal DCT, Swiss Microtechnology AG, Port, Switzerland).. The intraocular pressure was also measured with this tonometer. The examinations were performed pre-operatively and post-operatively at the first week and first month. The mean age of the patients was 58.8 ± 12.4 years. The mean sub-foveal choroidal thickness and ocular pulse amplitude values did not change statistically significantly after the operations at the follow-up visits (p>0.05). Also, there were no important correlations between cardiopulmonary bypass time and mean sub-foveal choroidal thickness and ocular pulse amplitude changes at the post-operative first week (p>0.05). The intraocular pressure values were decreased markedly at the control visits (p<0.05). Sub-foveal choroidal thickness and ocular pulse amplitude are unchanged, while intraocular pressure decreases one week and one month after cardiopulmonary bypass.

Clinical Use of a New Position-independent Rebound Tonometer

To compare intraocular pressure (IOP) measurements obtained by rebound tonometry (Icare PRO tonometer), applanation tonometry (Goldmann and Perkins tonometry), and dynamic contour tonometry in the upright and the supine positions, and to investigate the influence of axial length and central corneal thickness. Ninety-nine right eyes of 99 patients with glaucoma or suspect for glaucoma, admitted to our department between November 2010 and January 2011 to obtain an IOP profile including supine measurements, were included in our study. IOP measurements were obtained in an upright position using an Icare PRO rebound (RTPRO), a Goldmann applanation (GAT), and a Pascal dynamic contour tonometer (DCT). In the supine position, IOP measurements were taken using the RTPRO and a Perkins hand-held applanation tonometer (PAT). The means and SDs for all tonometers were compared. Agreement between the tonometers was calculated using the Bland-Altman method. The mean IOPs obtained in the upright position were 17.7 ± 8.0 mm Hg (RTPRO), 17.6 ± 7.8 mm Hg (GAT), and 19.9 ± 6.6 mm Hg (DCT). Correlation analysis of these data indicated a good correlation between IOP readings obtained using RTPRO and GAT (r=0.951; P<0.001), and RTPRO and DCT (r=0.897; P<0.001). Bland-Altman analysis revealed mean differences (bias) between RTPRO and GAT, and between RTPRO and DCT of 0.1 mm Hg and -1.8 mm Hg, with 95% limits of agreement of -3.6 to 3.8 mm Hg and -7.3 to 3.6 mm Hg, respectively. In the supine position, the mean IOPs were 19.2 ± 6.4 mm Hg using the RTPRO and 19.6 ± 6.2 mm Hg using the PAT. Measurements obtained with the RTPRO, either in the upright or in the supine position, show good correlation and agreement with those provided by applanation and dynamic contour tonometry. The study was registered with the DRKS (German Clinical Trials Register; http://www.germanctr.de; DRKS00000581).