Peripheral anterior synechiae and ultrasound biomicroscopic parameters in angle-closure glaucoma suspects

Comparison of intraocular pressure and anterior segment parameters in subjects with asymmetrical primary angle closure disease

BACKGROUND

To compare intraocular pressure (IOP) and anterior segment parameters between eyes with unilateral primary angle closure glaucoma (PACG) and their fellow eyes with primary angle closure (PAC) or primary angle closure suspect (PACS).

METHODS

Subjects underwent anterior segment imaging using 360-degree swept-source optical coherence tomography (SS-OCT, CASIA Tomey, Nagoya, Japan) and ocular investigations including gonioscopy and IOP measurement. Each SS-OCT scan (divided into 8 frames, 22.5 degrees apart) was analysed and an average was obtained for the following anterior segment parameters: iridotrabecular contact (ITC), angle opening distance (AOD750), iris thickness and curvature, anterior chamber width, depth and area (ACW, ACD and ACA) and lens vault (LV).

RESULTS

Among 132 unilateral PACG subjects (mean age: 62.91 ± 7.2 years; 59.1% male), eyes with PACG had significantly higher presenting IOP (24.81 ± 0.94 vs. 18.43 ± 0.57 mmHg, p < 0.001), smaller gonioscopic Shaffer grade (2.07 ± 0.07 vs. 2.31 ± 0.07, p < 0.001) and a greater extent of peripheral anterior synechiae (PAS, 1.21 ± 0.21 vs. 0.54 ± 0.16 clock hours, p = 0.001). PACG eyes also exhibited increased ITC, ITC area, greater LV and smaller AOD750, ACD and ACA (all p < 0.05). Using the forward stepwise regression model, an increase in 1 mmHg in presenting IOP before laser peripheral iridotomy (LPI) increases the odds of having PACG by 9% (95% confidence interval 5%-14%).

CONCLUSIONS

PACG eyes have higher presenting IOP, smaller anterior segment parameters, greater extent of PAS, and larger LV compared to their fellow eyes with angle closure. Narrower anterior chamber dimensions and higher presenting IOP before LPI may increase risk of chronic elevated IOP and glaucomatous optic neuropathy after LPI.

Comparison of intraocular lens power calculation formulas in patients with a history of acute primary angle-closure attack

BACKGROUND

To compare the accuracy of nine intraocular lens (IOL) power calculation formulas, including three traditional formulas (SRK/T, Haigis, and Hoffer Q) and six new-generation formulas (Barrett Universal II [BUII], Hill-Radial Basis Function [RBF] 3.0, Kane, Emmetropia verifying optical [EVO], Ladas Super, and Pearl-DGS) in patients who underwent cataract surgery after acute primary angle closure (APAC).

METHODS

In this retrospective cross-sectional study, 44 eyes of 44 patients (APAC) and 60 eyes of 60 patients (control) were included. We compared the mean absolute error, median absolute error (MedAE), and prediction error after surgery. Subgroup analyses were performed on whether axial length (AL) or preoperative laser peripheral iridotomy affected the postoperative refractive outcomes.

RESULTS

In the APAC group, all formulas showed higher MedAE and more myopic shift than the control group (all P < 0.05). In APAC eyes with AL ≥ 22 mm, there were no differences in MedAEs according to the IOL formulas; however, in APAC eyes with AL < 22 mm, Haigis (0.49 D) showed lower MedAE than SRK/T (0.82 D) (P = 0.036) and Hill-RBF 3.0 (0.54 D) showed lower MedAE than SRK/T (0.82 D), Hoffer Q (0.75 D) or Kane (0.83 D) (P = 0.045, 0.036 and 0.027, respectively). Pearl-DGS (0.63 D) showed lower MedAE than Hoffer Q (0.75 D) and Kane (0.83 D) (P = 0.045 and 0.036, respectively). Haigis and Hill-RBF 3.0 showed the highest percentage (46.7%) of eyes with PE within ± 0.5 D in APAC eyes with AL < 22 mm. Iridectomized eyes did not show superior precision than the non-iridotomized eyes in the APAC group.

CONCLUSIONS

Refractive errors in the APAC group were more myopic than those in the control group. Haigis and Hill-RBF 3.0 showed high precision in the eyes with AL < 22 mm in the APAC group.

Evaluation of ciliary cleft changes after phacoemulsification using ultrasound biomicroscopy in dogs with cataracts

Introduction

Glaucoma is one of the most serious complications that causes irreversible blindness after phacoemulsification in dogs; however, a clear mechanism has not been elucidated. This study aimed to analyse the possible anatomical factors associated with glaucoma after phacoemulsification using parameters that reflect the anatomical characteristics of dogs.

Materials and methods

A total of 69 eyes of 48 dogs were included in this study. The patients were divided into three groups: normal eye (n = 18), cataract (n = 39), and post-phacoemulsification for at least 2 months after surgery (post-phaco, n = 12). For further analysis, the dogs were subdivided into two groups according to cataract stage: phacoemulsification non-candidate and candidate groups. Non-cataracts and incipient cataracts were categorized into the non-candidate group, whereas immature and mature cataracts were categorized into the candidate group. Measurements of the ciliary cleft parameters, including the area of the ciliary cleft (CCA), length of the ciliary cleft (CCL), width of the ciliary cleft (CCW), iridocorneal angle, and angle opening distance, were obtained using ultrasound biomicroscopy.

Results

CCA, CCL, and CCW were significantly higher in the candidate group than in the non-candidate group. CCA, CCL, and CCW were significantly reduced in the post-phaco group compared to those in the cataract group. Based on these results, we found that the ciliary cleft expanded in cataract-affected eyes and narrowed after phacoemulsification. This may indicate that the space between the trabecular meshworks became narrower, potentially leading to an increase in the resistance of the aqueous humor.

Conclusion

A narrowed ciliary cleft after phacoemulsification may be an anatomical factor associated with glaucoma.

Association of peripheral anterior synechiae with anterior segment parameters in eyes with primary angle closure glaucoma

To investigate the association of peripheral anterior synechiae (PAS) with intraocular pressure (IOP) and anterior-segment parameters in subjects with primary angle-closure glaucoma (PACG). A total of 267 subjects with PACG were recruited and underwent gonioscopy and anterior-segment optical coherence tomography (ASOCT). Customized software was used to measure ASOCT parameters, including angle opening distance (AOD750) and trabecular-iris-space-area (TISA750) at 750 µm from the scleral spur, anterior chamber depth, width, area and volume (ACD, ACW, ACA, ACV), iris thickness (IT750), iris area (IAREA), and lens vault (LV). Presenting IOP was defined as the first IOP reading before the initiation of IOP-lowering treatment. The mean age of the 267 subjects was 67.0 ± 8.9 years, 140 (52.4%) were male, and 246 (92.1%) were of Chinese ethnicity. PAS was present in 122 (45.7%) subjects, and was most frequently found in the superior quadrant (79.5%). Subjects with PAS had greater presenting IOP (28.7 ± 12.9 vs 22.4 ± 9.7 mmHg, p < 0.001), narrower AOD750 (p < 0.001), smaller TISA750 (p < 0.001), ACD (p = 0.04), ACA (p = 0.02), ACV (p = 0.01) and larger LV (p = 0.01) compared to PACG eyes without PAS. No significant differences were noted for iris parameters. A multivariate logistic regression analysis showed that higher presenting IOP (β = 0.20, p < 0.001), worse visual field mean deviation (β = - 0.20, p = 0.01) and narrower AOD750 (β = - 0.25, p = 0.03) were the only parameters that significantly correlated with the extent of PAS in clock hours. Almost one-half of the subjects with PACG demonstrated PAS; these eyes were associated with higher presenting IOP, smaller anterior segment dimensions and more severe disease.

Association Between Anterior Chamber Angle and Corneal Endothelial Cell Density in Chronic Angle Closure

Purpose

To study the association between corneal endothelial cell density (ECD) and degree of anterior chamber angle (ACA) opening in eyes with chronic angle closure glaucoma.

Methods

The study was conducted at JEC Eye Hospitals in Indonesia. Treatment-naïve patients aged ≥40 years with IOP >21 mmHg and peripheral anterior chamber depth (ACD) grade 2 or less by Van Herick's technique were recruited. Trabecular iris angle (TIA; degree) was measured using anterior segment optical coherence tomography (AS-OCT) and classified as: grade 1 ≤10°, grade 2 11-20°, and grade 3 >20°. Noncontact specular microscopy was performed, and the following corneal parameters were obtained:ECD (cells/mm²), coefficient of variation (CV; μm²/cell), percentage of hexagonal cells, and central corneal thickness (CCT; μm).

Results

A total of 52 eyes from 52 subjects were recruited (16 grade 1 TIA, 24 grade 2 TIA, and 12 grade 3 TIA). Presenting IOP was not significantly different between groups. The median central corneal ECD was 2684.5 (1433-2934), 2587.0 (1902-3103), and 2441.0 (1659-3005) cells/mm² in grade 1, 2, and 3 TIA, respectively, with no significant differences across the groups (P = 0.67). The CV was lowest in grade 3 TIA (36.4 ± 7.2 μm2/cell), and highest in grade 1 TIA (38.3 ± 9.6 μm2/cell), but the differences were not significant (P = 0.74). Likewise, the percentage of hexagonality and CCT was not significantly different. TIA was not correlated with IOP but was modestly correlated with age.

Conclusion

The corneal ECD and morphological characteristics such as CV and hexagonality were not significantly different across various TIA grading in chronic angle closure. This may reflect the lack of chronic and gradual IOP insult on corneal endothelial parameters as TIA did not show direct effect towards IOP.

The effects of peripheral anterior synechiae on refractive outcomes after cataract surgery in eyes with primary angle-closure disease

Objective of the study was to investigate the effects of peripheral anterior synechiae (PAS) on refractive outcomes after cataract surgery in eyes with primary angle-closure disease (PACD).This is a retrospective, cross-sectional study. Seventy eyes of 70 PACD patients who underwent phacoemulsification and intraocular lens implantation. Patients were divided into 2 groups based on the presence of PAS on preoperative gonioscopy. The predictive power of the intraocular lens was calculated by the SRK/T, Hoffer Q, Haigis, and Holladay formulae. The mean absolute error (MAE) and predicted refractive errors were compared between PAS (+) and PAS (-) groups. We also evaluated the refractive errors with regards to the extent of PAS in the subanalyses.The mean MAE was greater in the PAS (+) group with all formulae (0.61-0.70 diopters [D] vs 0.33-0.45 D, all P < .05). The eyes with PAS tended towards myopia (-0.30 D to -0.51 D vs -0.05 D to +0.24 D, all P < .05). However, the MAEs or predicted refractive errors were not different, irrespective of the extent of PAS in the subanalyses (all, P > .05).The presence or absence of PAS may influence the postoperative refractive outcomes in PACD patients.

Phacoemulsification, visco-goniosynechialysis, and goniotomy in patients with primary angle-closure glaucoma: A comparative study

OBJECTIVE

The aim of this study was to evaluate the effects of goniotomy on patients with primary angle-closure glaucoma who underwent "phacoemulsification and visco-goniosynechialysis."

MATERIALS AND METHODS

This prospective randomized clinical trial was carried out on 63 eyes of 61 patients (48-85 years) with primary angle-closure glaucoma who were enrolled. The subjects were randomly assigned into two groups. In the first group (32 eyes) and the second group (31 eyes), the patients underwent "phacoemulsification + visco-goniosynechialysis + goniotomy" and "phacoemulsification + visco-goniosynechialysis," respectively. Intraocular pressure and antiglaucoma medication were evaluated (1 week, as well as 1, 3, and 6 months after the surgery). Anterior segment optical coherence tomography parameters (Casia, Tomey, USA) and goniotomy were evaluated preoperatively and 6 months after the surgery.

RESULTS

The mean intraocular pressure lowering the effects in the "phacoemulsification + visco-goniosynechialysis + goniotomy" group was higher than that in the "phacoemulsification + visco-goniosynechialysis" group (6.93 and 4.6, respectively). Furthermore, the difference in intraocular pressure between the two groups was significant at 3 months (P = 0.014) and 6 months (P = 0.021) after the surgery. There was no difference in anterior segment optical coherence tomography findings before the intervention; however, after the intervention, the anterior segment optical coherence tomography indices were significantly different between the two groups. Moreover, the difference in "phacoemulsification + visco-goniosynechialysis + goniotomy" indices was more than the changes in the "phacoemulsification + visco-goniosynechialysis" group.

CONCLUSION

The results of this study showed that phacoemulsification + visco-goniosynechialysis + goniotomy is a more effective surgery than phacoemulsification + visco-goniosynechialysis alone in undercounted primary angle-closure glaucoma.

Effect of Lateral Decubitus Body Posture on Anterior Chamber Angle in Healthy Subjects: An Anterior Segment Optical Coherence Tomography Study

PURPOSE

To investigate the effect of the lateral decubitus (LD) position on the anterior chamber (AC) angle in healthy subjects.

MATERIALS AND METHODS

Twenty-three healthy young subjects were included in this prospective observational study. We measured AC angle parameters in the sitting and the left LD positions using anterior segment optical coherence tomography (Visante OCT): trabecular-iris angle (TIA), angle opening distance (AOD500), trabecular-iris space area (TISA500), anterior chamber width, lens vault, and anterior chamber depth. The Wilcoxon signed-rank test was used to compare the parameters between different body positions. Interobserver reproducibility of AC angle measurements was assessed by intraclass correlation coefficients.

RESULTS

Postural alterations from sitting to the left LD position significantly reduced the AC angle on the temporal side in right eyes (TIA: 39.53±2.38 to 38.31±3.47 degrees; AOD500: 0.72±0.13 to 0.65±0.08; TISA500: 0.25±0.06 to 0.22±0.04; all P<0.05), whereas no significant changes were noted on the nasal side. Contrastingly, a significant decrease in the AC angle on the nasal side was noted for left eyes (TIA: 39.49±2.24 to 38.17±2.76 degrees; AOD500: 0.68±0.09 to 0.64±0.10; TISA500: 0.23±0.04 to 0.21±0.03; all P<0.05). Anterior chamber width and anterior chamber depth were unaffected by postural alterations, but lens vault significantly was reduced following a shift to the left LD position.

CONCLUSIONS

The AC angle parameters on the nondependent side of the eye in the LD position were significantly reduced compared with those in the sitting position. Therefore, postural shift from sitting to the LD position may induce alterations in the AC angle.

Old and new in exploring the anterior chamber angle

Angle-closure glaucoma includes a number of entities with closed angle, elevated intraocular pressure, in association with optic nerve damage and visual field defects as common markers. These entities are characterized by irido-trabecular apposition, irido-trabecular synechiae or both. The angle configuration must be systematically checked at least one time in patients presenting with raised intraocular pressure or glaucoma. Gonioscopy represented for a long time the gold standard for clinically assessing anterior chamber angle structures and their configuration. However, the interpretation of gonio-scopic findings is subjective and only semiquantitative. With the development of new imaging techniques of the anterior segment, new analysis methods have also emerged. Ultrabiomicroscopy was the first method of analyzing the anterior segment and is still the only imaging technique for all anterior segment structures (especially the ciliary body). Another method is optical coherence tomography, a non-contact technique by which angle configuration can be assessed in a more rapid and less invasive manner. Recently developed Pentacam technology could represent in the near future a more quantitative, rapid and non-invasive screening tool which could allow early detection of angle closure glaucoma and narrow angle configurations by measuring a set of anterior chamber parameters. List of abbreviations: ACG -angle closure glaucoma, ASOCT-anterior segment optical coherence tomography UMB- ultrasound biomicroscopy (ultrabiomicroscopy), PAS-posterior angle synechiae ACD-anterior chamber depth, ACV-anterior chamber volume, PLI-periphery laser iridotomy.

Comparison of Ciliary Body Anatomy between American Caucasians and Ethnic Chinese Using Ultrasound Biomicroscopy

PURPOSE

To compare the ciliary body morphology between the Caucasians and Chinese, and to determine the associated anterior segment parameters.

METHODS

The study groups were comprised of four age- and gender-matched cohorts: American Caucasians, American Chinese, southern and northern mainland Chinese. Ultrasound biomicroscopy (UBM) was performed to assess the following measurements of the ciliary body: trabecular-ciliary process distance (TCPD), trabecular-ciliary process angle (TCA) and ciliary body thickness at 1 mm posterior to the scleral spur (CBT1). A-scan ultrasonography was used to measure lens thickness (LT) and relative lens position (RLP), defined as (ACD + LT/2)/AL.

RESULTS

There were 109, 111, 115 and 117 subjects enrolled in the American Caucasian, American Chinese, and southern and northern mainland Chinese groups, respectively. Collectively, the Chinese had smaller TCPD (0.834 ± 0.234 versus 0.940 ± 0.236 mm, p < 0.001) and TCA (75.1 ± 17.9 versus 85.0 ± 21.5, p < 0.001) than Caucasians. No difference was found between the three Chinese subgroups, therefore they were combined as one for the following analyses. After multiple linear regression analysis, adjusting for age, gender, spherical equivalent (SE) and axial length (AL), TCPD and TCA were positively associated with CBT1 and RLP, but negatively correlated with LT in the whole sample. The ethnic Chinese had significantly smaller CBT1 (SRC = -0.177, p < 0.001) and RLP (SRC = -0.254, p < 0.001) than that of Caucasians.

CONCLUSIONS

Compared with the Caucasians, the Chinese had a thinner ciliary body and a more anteriorly positioned lens, which may contribute to more anteriorly positioned ciliary processes in this population. These findings might help to explain the higher prevalence of angle closure in the Chinese.

Methods of measuring the iridocorneal angle in tomographic images of the anterior segment of the eye

INTRODUCTION

This paper presents the problem of automatic measurement of the iridocorneal angle in tomographic images of the anterior segment of the eye. It includes the results of the comparison of well-known methods for measuring the iridocorneal angle with new methods, proposed in this paper. All these methods concern tomographic image analysis and processing.

MATERIAL AND METHOD

In total, approximately 100'000 tomographic images (from about 6'000 patients) were analysed. They were obtained using two devices: SOCT Copernicus (Optopol Tech. SA, Zawiercie, Poland) and Visante OCT (Carl Zeiss Meditec, Inc, Dublin, California, USA). The patients, aged 12 to 78 years with varying degrees of the iridocorneal angle pathology, were from the region of Silesia, Poland. The images were in DICOM or RAW formats and analysed in the software developed by the authors for the purposes of this study.

RESULTS

The results indicate that the measurement method proposed by the authors, which is based on the calculation of the minimum distance between the iris and the cornea in the adopted area, is the most accurate. For this method sensitivity was 0.88, specificity 0.89 and the area under the Receiver Operating Characteristic curve (AUC) was 0.88. The other known methods for measuring the iridocorneal angle gave worse results, that is, for example, for the measurement of the distance between the iris and the cornea AUC = 0.87, sensitivity = 0.86 and specificity = 0.71. For another well-known method of measuring the iridocorneal angle AUC = 0.77, sensitivity = 0.82 and specificity = 0.61.

CONCLUSIONS

The study proved that the proposed method of measuring the minimum distance between the iris and the cornea within the adopted area is the most effective in the classification of the iridocorneal angle in patients with a high degree of pathology of all the compared measurement methods based on tomographic images. However, it requires fully automated measurement.

Anterior-segment imaging for assessment of glaucoma

This article summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT) for assessment of the anterior segment in glaucoma. UBM systems use frequencies ranging from approximately 35 to 80 MHz, as compared with typical 10-MHz systems used for general-purpose ophthalmic imaging. OCT systems use low-coherence, near-infrared light to provide detailed images of anterior segment structures at resolutions exceeding that of UBM. Both technologies allow visualization of the iridocorneal angle and, thus, can contribute to the diagnosis and management of glaucoma. OCT systems are advantageous, being noncontact proceedures and providing finer resolution than UBM, but UBM systems are superior for the visualization of retroiridal structures, including the ciliary body, posterior chamber and zonules, which can provide crucial diagnostic information for the assessment of glaucoma.

[Ultrasound biomicroscopy in diagnosis of anterior segment pathology]

INTRODUCTION

Ultrasound biomicroscopy (UBM) is a non-invasive diagnostic procedure, developed in order to achieve better visualization of the anterior segment of the eye. The first clinical images were made in March 1990. The use of UBM at the Institute for Eye Diseases, Clinical Centre of Serbia, began in February 2007.

OUTLINE OF CASES

Due to a drop in visual acuity, the first patient was sent to the Institute for Eye Diseases, Clinical Centre of Serbia. The existence of the ciliary body tumour was suspected, so she underwent a UBM diagnostic procedure. UBM showed fibrin in the anterior chamber of the eye, occlusion of the pupil, and the absence of tumour. The second patient had a part of the chamber angle filled with solid lesion. UBM showed a solid tumour lesion filling the chamber angle in the lower part of the anterior chamber. The origin of the tumour was the ciliary body rather than the choroid which was shown by the B scan ultrasound. Lipodermoid was found by clinical examination of the third patient. He underwent UBM in order to exclude the involvement of the sclera under the lesion. UBM visualized a subconjunctival lesion lying on the sclera, reaching the limbus of the cornea.The difference in ultrasound reflection of the two tissues helped us to confirm that the sclera was not involved. Our fourth patient underwent an antiglaucomatous procedure, and the assessment of the chamber angle opening was the reason for the UBM examination. Parameters measured in the lower quadrants (6 o'clock) that we managed to obtain were the following: AOD (250 microm)--180 microm, AOD (500 microm)--400 microm, TIA--34.39 deg., ARA--0.25 mm2. Comparing them to normal values, we came to the conclusion that the chamber angle was open in the lower part of the anterior chamber.

CONCLUSION

Ultrasound biomicroscopy gives us plenty of useful information when it comes to diagnosing the anterior chamber pathology.