Iridocorneal Angle Measurements Research Articles

Morphometric analysis of the anterior chamber in patients with refractory glaucoma after micropulse cyclophotocoagulation

PURPOSE. To evaluate the anatomical-topographic parameters of the anterior chamber of the eye before and after micropulse cyclophotocoagulation (mCPC) in patients with refractory glaucoma in pseudophakic and phakic eyes.METHODS. The study included 60 patients (62 eyes) with moderate (7 eyes) and advanced (55 eyes) refractory glaucoma. Study groups were formed as follows: the 1st group consisted of 31 pseudophakic eyes (32 patients), the 2nd group included 31 phakic eyes (30 patients). All patients underwent mCPC according to a modified technique. To assess anatomical parameters patients underwent optical coherence tomography of the anterior segment (AS-OCT). Anterior chamber angle (ACA) and anterior chamber depth (ACD) were measured at specific follow-up time points after mCPC.RESULTS. Hypotensive effect by the end of 12-month follow-up was achieved in the patients of the first group in 83.1% of cases, in the second group — in 80.6% of cases (p<0.05). According to OCT findings, anterior chamber depth in patients with phakic eyes during the 12-month follow-up remained the same as before surgery — 2.43±0.21 (mm). In the other group with pseudophakic eyes, anterior chamber depth also did not change during the observation period, with an average value of 3.27±0.12 (mm). No significant changes (p>0.05) were found in the irido-corneal angle measurements in the 4 meridians over the entire follow-up period in both groups.CONCLUSION. Micropulse cyclophotocoagulation performed at fluence rate F=121 J/cm2 does not result in changes of structures of the anterior segment of the eye. The stability of anterior chamber anatomy as well as the absence of postoperative complications in early and longterm follow-up proved the minimal traumatic effect of this surgery in patients with refractory glaucoma.

The short-term effects of intravitreal bevacizumab injection on intraocular pressure, cornea, iridocorneal angle, and anterior chamber.

Transient increase in intraocular pressure (IOP), changes in anterior chamber parameters, and changes in aqueous humor dynamics may occur after intravitreal injections because of intravitreal volume changes. In this observational study, we investigated the early effects of intravitreal bevacizumab (IVB) injection on IOP, central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), and iridocorneal angle (ICA). The patients who had one single-dose IVB (2.5 mg/0.1 mL) injection were included in the study. The patients underwent IOP, CCT, CV, ACD, and ICA measurements before and 1 h and 1 day after the injection. Pre-injection and post-injection values were compared. Forty-two eyes of 42 patients were included in the study, and the mean age of patients was 60.1 ± 7.4 years. The mean IOP measurements before and after injection at 1 h and day 1 were 15 ± 2.4, 17.4 ± 2.4, and 14.7 ± 2.3, respectively. The mean IOP, CCT, and CV values 1 h after injection were significantly higher than pre-injection values (p < 0.05, p < 0.05, and p = 0.02, respectively). Conversely, mean ACD and ICA values 1 h after injection were significantly lower than pre-injection values (p = 0.01 for both). There were no statistically significant differences on the first day after injection for all parameters. IVB (2.5 mg/0.1 mL) injection causes transient increases in IOP and transient decreases in ACD and ICA at the first hour after injection. Related to elevation in IOP, CCT and CV may increase transiently. These changes return to baseline values on the first day after injection.

Intra-session repeatability of iridocorneal angle measurements in normal subjects and glaucoma patients using Scheimpflug-Placido disc topographer.

Intra-session repeatability of iridocorneal angle measurements in normal subjects and glaucoma patients using Scheimpflug-Placido disc topographer.

Characteristics and variability of iridocorneal angle: an anterior segment optical coherence tomography study

AbstractPurposeWe aimed to assess the iridocorneal angle by Anterior Segment Optical Coherence Tomography (AS‐OCT) and to identify relations between angle measurements and subject factors in a healthy Caucasian Tunisian population.MethodsA prospective cross‐sectional study was performed in 201 right eyes of 201 healthy subjects.All patients underwent a complete ophthalmic examination, automated refraction, ultrasound biometry and AS‐OCT examination at the same day. The iridocorneal angle measurements including trabecular iris angle (TIA), angle opening distance 500 (AOD500) and trabecular iris space area 500 (TISA500) were manually measured using AS‐OCT. Correlations and associations were examined between angle measurements and demographic, clinical and ocular factors.ResultsThe means recorded were TIA = 34.6 ± 11.4 degrees, AOD500 = 515 ± 260.7 µm and TISA = 500 0.178 ± 0.091 mm². We found that 90.3% of the iridocorneal angles were open.Correlations were detected between angle means and age (R = −0.414; p &lt; 0.01), intraocular pressure (R = −0.145; p &lt; 0.01), spherical error (R = −0.410; p &lt; 0.01), anterior chamber depth (R = 0.734; p &lt; 0.01), axial length (R = 0.489; p &lt; 0.01) and lens thickness (R = −0.519; p &lt; 0.01).No relation was observed with sex (p = 0.084).ConclusionsAS‐OCT is a non‐invasive tool to identify subjects at risk of angle closure. In this Caucasian population, 90.3 % of the iridocorneal angles were open. AOD 500 and TISA 500 were as reliable as TIA in iridocorneal angle assessment. The angle width was correlated with demographic and ocular factors. Among the main limitations, was the fact that we did not measure the lens vault despite the known contribution of this factor to angle width variation.

Comparison of iridocorneal angle parameters measured by spectral domain optical coherence tomography and ultrasound biomicroscopy in dogs.

To compare the measurements of iridocorneal angle parameters between spectral domain optical coherence tomography (SD-OCT) and ultrasound biomicroscopy (UBM) in dogs. A total of 47 eyes of dogs were scanned at the temporal limbus using SD-OCT and UBM. Iridocorneal angle (ICA) and angle opening distance (AOD) were measured from the obtained images accordingly. The intra-observer and inter-observer reproducibility were evaluated using the intraclass correlation coefficient. To evaluate intra-observer reproducibility, measurements of the first and second grading from the first examiner were compared. To evaluate inter-observer reproducibility, measurements between the two examiners were compared. Agreement between ICA and AOD for SD-OCT and UBM was evaluated using Bland-Altman plots. In the first grading, the mean ICA and AOD for SD-OCT were 31.4±6.4° and 641.4±270.8µm, respectively. The mean ICA and AOD for UBM were 32.0±4.8° and 700.4±238.8µm, respectively. For ICA and AOD measurements, intra-observer reproducibility was excellent for both devices, whereas inter-observer reproducibility was excellent for SD-OCT and good for UBM. The mean difference in ICA between SD-OCT and UBM was 0.6° with a limit of agreement (LoA) span of 18.9°. The mean difference in AOD between SD-OCT and UBM was 58.9µm with a LoA span of 804.4µm. Spectral domain optical coherence tomography is an effective non-contact imaging modality for the evaluation of canine iridocorneal angle parameters in a clinical setting. Reproducibility of measurements obtained is comparable or superior to UBM, but values obtained by SD-OCT and UBM for AOD are not interchangeable between devices.

The Effect of Uneventful Phacoemulsification on Intraocular Pressure and Anterior Segment Parameters in Pseudoexfoliation Syndrome.

Objectives:The aim of this study was to evaluate the effects of cataract surgery on anterior segment parameters and intraocular pressure (IOP) in non-glaucomatous pseudoexfoliation syndrome (PXS) eyes.Methods:The cohort consisted of 65 patients who were to undergo cataract surgery; the participants were divided into 2 groups: patients with PXS (n=35) and controls without PXS (n=30). A complete ophthalmic examination, measurement of IOP (using an applanation tonometer), and evaluation of anterior segment parameters using a Sirius Scheimpflug/Placido topography device (CSO Italy, Firenze, Italy) were performed on all patients both prior to and 1 month after surgery.Results:No significant difference was observed between groups in terms of preoperative IOP, pupil diameter, central corneal thickness, anterior chamber depth (ACD), anterior chamber volume (ACV), iridocorneal angle (ICA), or corneal volume (CV) values. A reduction in the postoperative mean IOP value was noted in both groups, with a difference of slightly >2 mmHg in the PXS group (PXS: p=0.000, control: p=0.002). Postoperatively, a statistically significant increase was observed in both groups in the ACD, ICA, ACV, and CV measurements. When comparing the preoperative and postoperative differences of the groups, the only parameter noted to be statistically significantly different was postoperative widening of the ICA. A greater degree of widening was noted in the PXS group (13.83±6.06°) compared with the control group (10.47±6.69°) (p=0.039).Conclusion:IOP values decreased and ACD values increased significantly following phacoemulsification in the PXS and the normal eyes. These findings support results reported in the literature. However, the results related to ICA changes are a new, previously unreported contribution. To more fully comprehend the effects of cataract surgery on patients with PXS in terms of ICA changes, prospective studies with a larger cohort are needed.

Iridocorneal angle assessment of companion rabbits using gonioscopy, spectral-domain optical coherence tomography (Optovue iVue® ), high-resolution ultrasound, and Pentacam® HR imaging.

Iridocorneal angle (ICA) narrowing is a known risk factor for primary glaucoma in multiple species, but has not been described in companion rabbits. This study aimed to develop an ICA grading scheme for companion rabbits to enable early glaucoma predisposition diagnosis. Twenty healthy rabbits of varying breeds and ages. Rabbits received complete ophthalmic examinations, including gonioscopy, and imaging of the ICA using spectral-domain optical coherence tomography (SD-OCT), Scheimpflug imaging (Pentacam® HR), and high-resolution ultrasound (HRUS). Angle opening distance (AOD) and angle recess area (ARA) of the ICA were measured and assessed for agreement using a Bland-Altman analysis. A five-stage gonioscopy grading scheme was created, and Spearman-rank test assessed for correlation between gonioscopy grades and ICA measurements. Differences among age and sex were analyzed with a nonparametric ANOVA and Wilcoxon rank-sum test, respectively. Analysis revealed AOD medians of 0.28mm for SD-OCT [95% CI: 0.24-0.31], 0.20mm for Pentacam® HR [95% CI: 0.18-0.21], and 0.25mm for HRUS [95% CI: 0.22-0.28]. The median ARA was 0.14mm2 for SD-OCT [95% CI: 0.117-0.163], 0.09mm2 for Pentacam® HR [95% CI: 0.082-0.100], and 0.06mm2 for HRUS [95% CI: 0.046-0.054]. The association between gonioscopy grade and SD-OCT ARA was significant (P<0.05), and there was a significant difference (P<0.001) between imaging modalities for both ARA and AOD. Gonioscopy grade correlated well with SD-OCT ARA. Therefore, SD-OCT is recommended as a noncontact method for evaluating companion rabbit ICA. Each imaging device should not be used interchangeably for ICA evaluation.

Identification and Characterization of Imaging Technique Errors and Artifacts Using Anterior-Segment OCT for Irido-Corneal Angle Evaluations in Glaucoma

Anterior-segment OCT (AS-OCT) platforms provide noninvasive and quantifiable evaluations of anterior chamber angle (ACA) anatomy. Although these ACA measurements have been validated with high repeatability and reproducibility, there is a paucity of data previously published regarding the technique errors and artifacts (TEA) that may occur during imaging of the ACA. The purpose of this study was to report on the types and frequency of imaging TEA that are seen in ACA evaluation of a large cohort of patients with open-angle glaucoma. Retrospective, cross-sectional design. Images were obtained with AS-OCT from 5082 eyes of 2541 patients with glaucoma and were reviewed at the Doheny Image Reading Center (DIRC). Images had been captured using AS-OCT devices from 4 different manufacturers (Zeiss Cirrus [Oberkochen, Germany], Heidelberg Spectralis [Heidelberg, Germany], Optovue RTVue [Fremont, CA], or Zeiss Visante). All images were analyzed by 2 independent and certified DIRC image readers for angle opening distance under Schwalbe's line (SL-AOD), and then re-reviewed by a DIRC-certified principal investigator to adjudicate nonconsensus measurements. Images were defined to have TEA when image readers were unable to confidently measure the SL-AOD. Type and frequency of TEA in the AS-OCT image. Of 5082 eyes reviewed, 208 images (4.09%) were found to have TEA that restricted proper visualization of irido-corneal angle structures and measurements of SL-AOD. The most common TEA was that the image readers were unable to identify Schwalbe's line (74% of TEA images). Other common TEA included poor visualization of the anterior iris surface (15%), misaligned scan location (11%), irregular corneal irregularities (5%), and illumination-related pupillary abnormalities (4%). This large-scale study presents the types and frequency of TEA found in AS-OCT-derived angle images. More than 95% of the images reviewed were usable for the quantification of irido-corneal angle measurements. Knowing the common types of TEA may help in enhancing the training of both human image readers and in the design of automated algorithms to improve image acquisition and image interpretation parameters. This will become especially useful as AS-OCT becomes more widely used in clinical practice for anterior chamber assessment.

Effect of Proparacaine 0.375%-Sodium Fluorescein 0.25% Eye Drop Mixture and Fluorescein Strip on Anterior Segment Parameters.

Purpose To determine the effect of proparacaine 0.375%-sodium fluorescein 0.25% eye drop mixture and fluorescein strip on anterior segment parameters commonly used in routine ophthalmology practice. Methods 115 healthy volunteers without any systemic or ocular disease were divided into two groups. 57 volunteers were in the proparacaine 0.375%-sodium fluorescein 0.25% eye drop mixture group, and 58 volunteers were in the fluorescein strip group. Measurements (CCT (central corneal thickness), topographic pupil diameter, AD (aqueous depth), ACV (anterior chamber volume), ICA (iridocorneal angle), LLD (limbus-limbus distance), and CV (corneal volume)) were taken before and at 1, 5, 15, and 30 minutes after application. Results 59 (51.3%) participants were female, and 56 (48.7%) were male. The mean age of the drop application group was 26.88 ± 8.03, and the mean age of the strip application group was 26.33 ± 7.28. The mean CCT was 556 ± 32 μm before drop application and 569 ± 30 μm in the 1st minute, 560 ± 32 μm in the 5th minute, and 559 ± 31 μm in the 15th minute. The change was statistically significant (p < 0.001, p=0.005, and p=0.013, resp.). Before the strip application, mean CCT was 552 ± 36 μm, while it increased to 556 ± 36 μm at the 1st minute, and this change was statistically significant (p=0.002). The mean CV before dropping was 59.29 ± 3.53 mm3 and 60.62 ± 3.53 mm3 at the 1st minute and 59.66 ± 3.70 mm3 at the 5th minute, which was statistically significant (p < 0.001 and p=0.034). Mean topographic pupil diameters at the 1st, 5th, 15th, and 30th minute after application of drops and strips were not significantly changed compared to the preapplication values in the AD, ACV, ICA, and LLD measurements. Conclusions Proparacaine 0.375%-sodium fluorescein 0.25% eye drop mixture and fluorescein strip application lead to a temporary change in CCT and CV of the anterior segment parameters. Anterior segment measurements with the Scheimpflug camera have to be done before topical fluorescein application.

Childhood Lensectomy Is Associated with Static and Dynamic Reduction in Schlemm Canal Size: A Biomechanical Hypothesis of Glaucoma after Lensectomy

To compare Schlemm canal (SC) and trabecular meshwork (TM) in children with healthy eyes and those with and without glaucoma after lensectomy. Cross-sectional observational study. Fifty children 4 to 16 years of age with healthy eyes and 48 children who underwent lensectomy (124 healthy and 72 postlensectomy eyes). Anterior segment (AS) OCT (Tomey SS-1000 CASIA; Tomey, Nagoya, Japan) of the nasal iridocorneal angle at 2 levels of accommodative effort (2.5 diopters [D] and 15 D). For each parameter and state of accommodation, a random effects model was fitted to estimate differences between healthy eyes and eyes with history of lensectomy. Dimensions of SC and TM and conventional AS OCT iridocorneal angle measurements. The horizontal diameter of SC and its cross-sectional area (CSA) are significantly smaller in eyes that have undergone lensectomy versus healthy eyes. Accommodative effort increases SC size in healthy eyes, but not in eyes that have undergone lensectomy. Lensectomy is associated with a reduction in SC size and a loss of physiologic SC dilatation during accommodative effort, which may reflect a reduction in outflow facility and may contribute to the development of glaucoma after lensectomy.

Dynamic Changes in Schlemm Canal and Iridocorneal Angle Morphology During Accommodation in Children With Healthy Eyes: A Cross-Sectional Cohort Study.

The purpose of this study was to explore changes in Schlemm canal (SC), trabecular meshwork (TM), and iridocorneal angle (ICA) morphology during accommodative effort in children and young adults. We acquired anterior segment optical coherence tomography images (AS-OCT) of the ICA and ciliary muscle (CM) of both eyes of 50 children age 4 to 16 years with healthy eyes, at two levels of accommodation: 2.5 and 15 diopters (D). Semiautomated nasal ICA measurements were as follows: angle opening distance at 500/750 μm (AOD-500, -750), trabecular iris space area at 500/750 μm (TISA-500, -750), and trabecular iris angle at 500/750 μm (TIA-500, -750). Manual measurements were as follows: anteroposterior and radial SC diameter (SC-APD, SC-RD), cross-sectional area of SC (SC-CSA) and TM height (TMH), TM length (TML), and TM density (TMD). CM width was measured at 1, 2, and 3 mm from the scleral spur (CM-1, CM-2, CM-3). For each parameter, a three-level random-effects model was fitted to estimate differences between the two levels of accommodation. With accommodative effort, SC diameters and CSA increase significantly, as do TM length and iridocorneal angle parameters. With increasing age, SC dimensions reduce. Angle parameters are smaller in eyes with greater spherical equivalent (hypermetropia). AS-OCT can be used to visualize dynamic morphologic changes in outflow structures with physiologic accommodation. The increase in SC dimensions with accommodative effort may contribute to the regulation of IOP in children.

Impacts of Implantable Collamer Lens V4c Placement on Angle Measurements Made by Optical Coherence Tomography: Two-Year Follow-up

To determine iridocorneal angle changes produced after 2 years of implantable collamer lens (ICL) V4c (STAAR Surgical AG, Nidau, Switzerland) placement by Fourier-domain optical coherence tomography (FD-OCT). Prospective interventional case series. In 54 eyes of 27 myopic subjects FD-OCT iridocorneal angle measurements were made before and 1month, 3months, 1 year, and 2 years after ICL implant. Trabecular-iris angle (TIA), angle opening distance 500μm from the scleral spur (AOD500), and iridotrabecular contact length (TICL) were compared among these time points and the nasal, temporal, and inferior quadrants. Preoperative TIAs were 49.5 ± 8.7, 48.3 ± 9.6, and 49.1 ±8.6 degrees for the nasal, temporal and inferior quadrants (P < .001). Corresponding values were 29.9 ± 10.4, 28.4 ± 10.8, and 28.8 ± 9.7 degrees at 1month and 27.3 ± 8.8, 26.8 ± 8.1, and 28.9 ± 7 degrees at 2 years of follow-up, indicating angle narrowing of 39%-45% and no further narrowing beyond 1month in the nasal (P= .133), temporal (P= .376), and inferior (P= 1.000) quadrants. Trabecular-iris contact (TIC) was observed in 8 eyes of 8 subjects, mostly only in the temporal quadrant. Mean TICL failed to vary during follow-up (307 ± 288μm at 3months and 225 ± 142μm at 2 years, P= .159). In response to ICL V4c implant, considerable angle narrowing was detected at 1month but this narrowing remained stable at 2 years. In the 8 cases of TIC, no progression of contact was observed beyond 3months postimplant.

Fourier domain optical coherence tomography to assess the iridocorneal angle and correlation study in a large Caucasian population.

BackgroundRecently, novel anatomic parameters that can be measured by optical coherence tomography (OCT), have been identified as a more objective and accurate method of defining the iridocorneal angle. The aim of the present study is to measure the iridocorneal angle by Fourier domain (FD) OCT and to identify correlations between angle measurements and subject factors in a large healthy Caucasian population.MethodsA cross sectional study was performed in 989 left eyes of 989 healthy subjects. The iridocorneal angle measurements: trabecular-iris angle (TIA), angle opening distance (AOD500) and trabecular-iris space area (TISA500) 500 μm from the scleral spur, were made using the FD-OCT RTVue®. Iris thickness was also measured. Correlations were examined between angle measurements and demographic and ocular factors. The main determinants of angle width were identified by multivariate linear regression.ResultsTIA could be measured in 94 % of the eyes, and AOD500 and TISA500 in 92 %. The means recorded were TIA 35.8 ± 12.2 degrees (range 1.5 to 76.1), AOD500 542.6 ± 285.4 μm (range 15 to 1755), and TISA500 0.195 ± 0.104 mm2 (range 0.02 to 0.62). The correlation between the temporal and nasal quadrant was R = 0.902 for TIA. The reproducibility of measurements was excellent (intraclass correlation coefficient >0.947). Mean angle width measurements were smaller in women (p = 0.02). Correlation was detected between angle means and anterior chamber volume (ACV; R = 0.848), anterior chamber depth (ACD; R = 0.818), spherical error (R = -0.619) and age (R = -0.487), while no correlation was observed with Intraocular pressure (R = -0.052). ACV emerged as the main determinant of TIA (R2 = 0.705; p < 0.001).ConclusionsIn this Caucasian population, strong correlation was detected between FD-OCT anterior angle measurements and ACV, ACD, spherical refractive error and sex, emerging the ACV as the main determinant of TIA.

Effects of Implantable Collamer Lens V4c Placement on Iridocorneal Angle Measurements by Fourier-Domain Optical Coherence Tomography

To assess by Fourier-domain optical coherence tomography (FDOCT) changes produced in iridocorneal angle measurements in patients undergoing Visian Implantable Collamer Lens (ICL) V4c (STAAR Surgical AG) placement. Prospective interventional case series. In 50 eyes of 25 myopic subjects consecutively scheduled for ICL implant, FDOCT (RTVue; Optovue Inc) iridocorneal angle measurements were made before and 1 and 3months after surgery. Trabecular-iris angle (TIA) and angle opening distance 500μm anterior to the scleral spur (AOD500) were compared among the quadrants nasal, temporal, and inferior, and correlations with ocular variables including lens vault were examined. Preoperative TIA was 48.7 ± 8.7, 48.2 ± 8.7, and 48.7 ± 9.3 degrees for the nasal, temporal, and inferior quadrants, with no differences (P= 1.000). Following ICL implant, corresponding values fell to 31.2 ± 11.5, 30.0 ± 10.7, and 29.7 ± 8.1 degrees at 1month postsurgery, indicating angle narrowing of 34%-42%, and to 30.6 ± 12.3, 30.1 ± 11.9, and 29.8 ± 12.3 degrees, respectively, at 3months postsurgery. Angle measurements failed to vary between 1month and 3months postsurgery (P= .481). In 8 eyes, iridotrabecular contact attributable to surgery was observed. One month after surgery, vault measurements correlated with TIA (R=-.309; P= .048). Six variables were identified as predictors of TIA at 1month postsurgery (R(2)= .907). Although considerable angle narrowing was detected 1month after ICL V4c implant, this narrowing remained stable at 3months postsurgery. Factors predictive of TIA could serve to identify suitable candidates for ICL placement.

Intra-session repeatability of iridocorneal angle measurements provided by a Scheimpflug photography-based system in healthy eyes.

The purpose of this study was to evaluate intra-session repeatability of measurements of the iridocorneal angle at different meridians in the nasal and temporal areas in healthy eyes using the Sirius Scheimpflug photography-based system in glaucoma analysis mode. A total of 43 eyes of 43 patients ranging in age from 36 to 79 years were enrolled in the study. All eyes received a comprehensive ophthalmologic examination including a complete anterior segment analysis with the Costruzione Strumenti Oftalmici [CSO] Sirius system. Three consecutive measurements of nasal and temporal angles at 0°, ±10°, ±20°, and ±30° meridians were obtained in order to assess the intra-session repeatability of iridocorneal angle measurements provided by the device using the glaucoma analysis mode. Within-subject standard deviation (Sw), coefficient of variation (CV), and intraclass correlation coefficient (ICC) values were calculated. The mean Sw was 1.07 ± 1.09°, 1.22 ± 1.53°, 0.66 ± 0.51°, 0.86 ± 0.57°, 0.68 ± 0.65°, 0.84 ± 0.68°, and 0.91 ± 0.70° at the temporal 30°, 20°, 10°, 0°, -10°, -20°, and -30° positions, respectively. Mean Sw was 3.13 ± 3.15°, 3.43 ± 3.63°, 2.75 ± 2.29°, 2.19 ± 1.55°, 1.90 ± 1.49°, 2.14 ± 1.74°, and 2.24 ± 2.06° at the temporal -30°, -20°, -10°, 0°, 10°, 20°, and 30° positions, respectively. Mean CV ranged from 1.36 ± 1.05 % (nasal 0° position) to 10.92 ± 13.95 % (nasal -20° position). ICC values ranged from 0.778 to 0.972. The glaucoma analysis mode of the Sirius system provides consistent measurements of the iridocorneal angle at different meridians in healthy eyes, with slightly less consistency for nasal measurements. It may be considered a clinically useful non-invasive technique for the detection of potentially occludable angles.

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.

Short-term Effects of Intravitreal Bevacizumab on Cornea and Anterior Chamber

Purpose: To determine the short-term effects of single-dose intravitreal bevacizumab injection on central corneal thickness (CCT), simulated keratometry (Sim K), anterior chamber depth (ACD), iridocorneal angle (ICA) and intraocular pressure (IOP) measurements.Design: Prospective, nonrandomized, interventional clinical trial.Materials and Methods: Forty-three eyes of 43 patients aged between 41 and 78 years (average 62 ± 13 years) received an intravitreal injection of 2.5 mg/0.1 mL bevacizumab. Patients who had not undergone additional intravitreal anti-vascular endothelial growth factor therapy within 6 months were included in the study. CCT, Sim K, ACD and ICA measurements were obtained with Sirius Topographer. IOP measurements were taken after topographic measurements with Goldmann applanation tonometer. The CCT, ACD, ICA and IOP measurements were taken before and after 3rd, 15th days and 1st month of intravitreal bevacizumab injection.Results: Pre- and postinjection of 3rd, 15th days and 1st month CCT (p = 0.999), Sim K (p = 0.746), ACD (p = 0.996), ICA (p = 0.632) and IOP (p = 0.707) measurements were not statistically different. Mean CCT (p = 1.000), Sim K (0.972), ACD (p = 0.998), ICA (0.667) and IOP (0.951) values were similar before and after 3rd day of bevacizumab injection. Mean CCT (p = 0.999), Sim K (p = 0.994), ACD (p = 1.000), ICA (p = 0.999) and IOP (p = 1.000) measurements were also similar before and after 15th day of injection. Preinjection and 1st month of postinjection CCT (p = 0.999), Sim K (p = 0.932), ACD (p = 0.998), ICA (p = 1.000) and IOP (p = 0.741) measurements did not change significantly.Conclusions: Single-dose intravitreal bevacizumab injection does not affect CCT, Sim K, ACD, ICA and IOP in short-term period.

The effect of topical latanoprost on anterior segment anatomic relationships in normal dogs

Topical latanoprost 0.005% is commonly used in dogs with primary angle closure glaucoma (PACG), and marked miosis has been reported in the literature. To further explore the effect of topical latanoprost on anterior segment anatomy, we performed iridocorneal angle biometrics in normal beagle dogs. Thirty-five normal female beagle dogs were assessed using anterior segment optical coherence tomography (AS-OCT). One eye of each dog was scanned with the AS-OCT in the superotemporal quadrant. One drop of latanoprost 0.005% was applied topically, and the OCT scan was repeated 30min later. Images were imported into ImageJ, and pupil diameter, anterior chamber angle, angle opening distance, angle recess area (ARA), anterior chamber hemifield, and anterior chamber depth were measured. A single drop of latanoprost resulted in marked miosis, anterior bowing of the peripheral iris, narrowing of the iridocorneal angle, and shallowing of the anterior chamber. The anterior segment parameters demonstrated a significant reduction (P-value≤0.001) from baseline following latanoprost with the exception of the ARA (P=0.07). Latanoprost significantly decreases pupil diameter and narrows the iridocorneal angle in normal female beagle dogs. Therefore, the utility of latanoprost as a prophylactic treatment for PACG in fellow eyes may be limited. Studies using quantitative iridocorneal angle measurements in goniodysgenic dogs are warranted to understand the changes in iridocorneal angle morphology that occur in PACG in response to topical application of latanoprost.

Iridocorneal angle measurements in mammalian species: normative data by optical coherence tomography

Objective Gonioscopy provides limited quantitative information to compare the iridocorneal anatomy across different species. In addition, the anatomic relationships by histologic examination are altered during processing. As a result, the comparative anatomy of the iridocorneal angle across several mammalian species was evaluated by Optical Coherence Tomography (OCT). Methods Cats, beagle dogs, minipigs, owl monkeys, cynomolgus monkeys, and rhesus monkeys (n = 6 or 7 per species) were evaluated. Imaging was performed using the OCT. The anterior chamber angle (ACA), angle opening distance (AOD), and the angle recess area (ARA) were evaluated. Results AC angle: cat (63 ± 6°) > owl monkey (54 ± 4°) > beagle dog (42 ± 4°) > minipig (40 ± 3°) > rhesus monkey (36 ± 1°) > cynomolgus monkey (34 ± 2°). AOD: cat (3.3 ± 0.5 mm) > owl monkey (2.05 ± 0.2 mm) > beagle dog (1.08 ± 0.1 mm) > rhesus monkey (0.92 ± 0.06 mm) > minipig (0.64 ± 0.04 mm) > cynomolgus monkey (0.43 ± 0.03 mm). ARA: cat (3.5 ± 0.1 mm(2) ) > owl monkey (1.41 ± 0.2 mm(2) ) > dog (0.88 ± 0.1 mm(2) ) > rhesus monkey (0.62 ± 0.06 mm(2) ) > minipig (0.21 ± 0.05 mm(2) ) > cynomolgus monkey (0.15 ± 0.01 mm(2) ). Conclusions This study benchmarks the normative iridocorneal angle measurements across different mammalian species by OCT. These data can be useful to compare iridocorneal angle measurements in disease states as OCT evolves as a common diagnostic tool in veterinary ophthalmic research and practice.

Estudo comparativo das estruturas do segmento anterior de olhos de cães normais e com catarata, portadores ou não de Diabetes mellitus, avaliados por biomicroscopia ultrassônica

A catarata representa uma das principais causas de cegueira em cães, sendo que as alterações metabólicas provocadas pelo Diabetes mellitus (DM), constituem a segunda causa mais comum de catarata nesta espécie. A biomicroscopia ultrassônica (UBM) é um método ultrassonográfico de alta frequência (50 MHz) que permite a obtenção de imagens do modo B de qualidade microscópica. Este estudo objetivou, por meio do uso da UBM, comparar as estruturas do segmento anterior de olhos de cães com catarata, diabética e não-diabética, às de cães normais, para verificar possíveis alterações decorrentes do DM. Os parâmetros avaliados foram espessura da córnea, profundidade da câmara anterior, aumento de celularidade no interior da câmara anterior e medida do ângulo iridocorneal. Foram realizados exames de 87 olhos de 47 animais da espécie canina, divididos em 3 grupos: grupo controle (GCO), grupo de portadores de catarata não-diabéticos (GCAT) e o grupo dos diabéticos (GDM). Os resultados revelam que o grupo dos diabéticos apresentou maiores espessuras de córnea que os demais grupos enquanto o grupo controle apresentou maiores câmaras anteriores. Encontrou-se aumento de celularidade em câmara anterior apenas nos grupos com catarata. Quando analisadas as medidas do ângulo iridocorneal, não houve diferença entre os 3 grupos. Com base no que foi aferido, permite-se concluir que olhos de cães diabéticos com catarata apresentam maior espessura de córnea central que olhos de cães com catarata de outras etiologias e de cães normais, que há diminuição da câmara anterior, com aumento de celularidade, em olhos de cães com catarata, quando comparados a cães normais e que não há diferença na medida do ângulo iridocorneal em olhos de cães com catarata, diabética ou não, e de cães normais.