Ultrasound biomicroscopy. II. Intraobserver and interobserver reproducibility of measurements

Ultrasound in ocular oncology: Technical advances, clinical applications, and limitations

Due to its accessibility and ability for real-time image acquisition of ocular structures, ultrasound has high utility in the visualization of the eye, especially in ocular oncology. In this minireview, we summarize the technical rationale and applications of ultrasound modalities, A-scan, B-scan, high-frequency ultrasound biomicroscopy (UBM), and Doppler measurement. A-scan ultrasound uses a transducer of 7-11 MHz, making it useful for determining the echogenicity of ocular tumors (7-8 MHz) and measuring the axial length of the eye (10-11 MHz). B-scan ultrasound operates at 10-20 MHz, which can be used for measuring posterior ocular tumors while UBM operates at 40-100 MHz to evaluate anterior ocular structures. Doppler ultrasonography allows for the detection of tumor vascularization. While ultrasonography has numerous clinical applications due to its favorable penetration compared with optical coherence tomography, it is still limited by its relatively lower resolution. Ultrasound also requires an experienced sonographer due to the need for accurate probe localization to areas of interest.

Effect of Topical Pilocarpine Instilled Before Laser Peripheral Iridotomy on Regional Iris Thickness in Primary Angle Closure Disease: A Swept-Source Anterior Segment Optical Coherence Tomography Pilot Study

PURPOSE

To determine whether the temporal-superior or the nasal-superior iris area becomes thinner (more optimal) for laser peripheral iridotomy (LPI) after pilocarpine instillation in primary angle closure disease (PACD); and to identify an angle for optimal penetration of the laser beam.

PATIENTS AND METHODS

Iris thickness at 2 mm from the iris root in the preset scanning axes was measured using swept-source anterior segment optical coherence tomography before and 60 minutes after the instillation of pilocarpine 2% in one eye of 30 consecutive Japanese PACD patients with thick, dark brown iris. Iris thickness at 1:30 and 10:30 clock hour positions were evaluated in sagittal and oblique directions, resulting sagittal iris thickness (SIT) and minimum iris thickness (MIT) parameters, respectively.

RESULTS

Compared to the baseline values, iris thickness decreased significantly (P < .001) in both locations after pilocarpine instillation. Both before and after pilocarpine instillation the temporal-superior iris thickness was significantly smaller than the nasal-superior thickness (P ≤ .001). After pilocarpine instillation, the temporal-superior iris was significantly thinner in an approximately 13° angle direction temporal to the sagittal direction than in the sagittal direction (MIT: 0.322 mm; SIT: 0.346 mm, P < .001).

CONCLUSIONS

After pilocarpine instillation, the temporal-superior iris and an approximately 13° angle temporal to the sagittal direction may provide an optimal location and laser beam angle for LPI in PACD eyes.

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

OBJECTIVE

To compare the measurements of iridocorneal angle parameters between spectral domain optical coherence tomography (SD-OCT) and ultrasound biomicroscopy (UBM) in dogs.

ANIMALS STUDIED AND PROCEDURES

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.

RESULTS

In the first grading, the mean ICA and AOD for SD-OCT were 31.4 ± 6.4° and 641.4 ± 270.8 µm, respectively. The mean ICA and AOD for UBM were 32.0 ± 4.8° and 700.4 ± 238.8 µm, 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 58.9 µm with a LoA span of 804.4 µm.

CONCLUSIONS

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.

Anterior ophthalmic imaging

Improvements in imaging chips and computer processing power have brought major advances in imaging of the anterior eye. Digitally captured images can be visualised immediately and can be stored and retrieved easily. Anterior ocular imaging techniques using slitlamp biomicroscopy, corneal topography, confocal microscopy, optical coherence tomography (OCT), ultrasonic biomicroscopy, computerised tomography (CT) and magnetic resonance imaging (MRI) are reviewed. Conventional photographic imaging can be used to quantify corneal topography, corneal thickness and transparency, anterior chamber depth and lateral angle and crystalline lens position, curvature, thickness and transparency. Additionally, the effects of tumours, foreign bodies and trauma can be localised, the corneal layers can be examined and the tear film thickness assessed.

Comparability of corneal thickness and opacity depth assessed by OCT and UBM

OBJECTIVE

To compare the measurement of central thickness and depth of involvement of opacity-bearing corneas at different intensities (mild, moderate, and dense) using different instruments: Visante and Optovue OCTs, ultrasound biomicroscopy (UBM), and ultrasound pachymetry (central thickness).

METHODS

Sample of 102 eyes: 70 eyes (68.63 %) with corneal opacity; 32 eyes (31.37%) with normal corneas. Corneal opacity grading included mild (28 eyes, 40.00 %), moderate (27 eyes, 37.57 %), and dense (15 eyes, 21.43 %). Opacity intensity was graded and documented. Central corneal thickness was determined using Optovue and Visante OCTs, ultrasound pachymetry, and UBM VuMax (50 MHz), and depth of corneal opacity, using Optovue and Visante OCTs and UBM.

RESULTS

Total corneal thickness of the control group showed differences with a small correction factor using Optovue OCT (534.03 ± 39.88 μm), Visante OCT (523.72±38.70 μm), and ultrasound pachymetry (529.84 ± 39.76 μm), and were higher when compared to UBM (492.06 ± 37.93 μm). In mild opacity, depth measurements were the same with OCT Optovue and Visante and higher than those by UBM. In moderate opacities, there were no differences in measurements by different instruments. In dense opacities, OCT Optovue and Visante measurements were the same and higher than those by UBM.

CONCLUSIONS

Central corneal thickness measurements were considered higher in corneas with opacity than in normal corneas. We observed that the greatest thicknesses were measured in corneas with dense opacities. There was a difference between the measurements taken by different instruments, both in central thickness and in opacity depth in cases of mild and dense opacity, and no difference in moderate opacity.

Ultrasound Biomicroscopy Documented Anterior Uveal Melanoma Regression after Ruthenium-106 Plaque Therapy

Introduction

Ultrasound biomicroscopy (UBM) is the only widely used method for the evaluation of anterior uveal melanoma (AUM).

Objective

Documentation of regression of AUM treated with ruthenium-106 (Ru-106) plaque types CCB and CCC using UBM.

Methods

This single institution-based retrospective case series involved 10 Caucasian patients with AUM followed after brachytherapy with UBM from January 2014 until February 2019. The largest prominence of the tumor perpendicular to the sclera or the cornea (including scleral/corneal thickness) (D) and the largest basal dimension (B) were measured in millimeters with UBM for all patients prior to the brachytherapy and at 4-month interval follow-up. Tumor regression was calculated as a percentage of decrease in the initial D and B values.

Results

The study involved 10 patients with a mean age of 64.4 years (yr) (range 46-80 yr). D ranged from 1.82 to 5.5 mm (median 2.99 mm) and B from 2.32 to 12.38 mm (median 4.18 mm). The apical radiation dose in all patients was 100 Gy. The median follow-up was 42.02 months. Regression for D was 21.11 ± 13.66%, 31.09 ± 14.66%, and 34.92 ± 19.86% at 1st, 2nd, and 3rd year of the follow-up, respectively, while for B it was 21.58 ± 16.05%, 28.98 ± 17.71%, and 32.06 ± 18.96%, respectively. Tumor recurrence was documented in 2/10 patients.

Conclusion

The major regression of AUM, treated with Ru-106 plaque types CCB and CCC, was documented in the first 2 years after brachytherapy in our study group. In the following years, only minimal regression was documented that warns of the need for close monitoring and active search for local recurrences.

Clinical Features of Iris Cysts in Long-Term Follow-Up

This study evaluated the characteristics and clinical course of patients with iris cysts in the long-term follow-up (24–48 months). We retrospectively analyzed the medical records of 39 patients with iris cysts (27 women and 12 men). Age, visual acuity, intraocular pressure (IOP), slit-lamp evaluation, and ultrasound biomicroscopy images were assessed. The mean age at diagnosis was 40.6 ± 17.48 years. Thirty (76.9%) cysts were peripheral, five (12.8%) were located at the pupillary margin, two (5.1%) were midzonal, and two (5.1%) were multichamber cysts extending from the periphery to the pupillary margin. A total of 23 (59%) cysts were in the lower temporal quadrant, 11 (28.2%) were in the lower nasal quadrant, and 5 (12.8%) were in the upper nasal quadrant. Cyst size was positively correlated with patient age (rs = 0.38, p = 0.003) and negatively correlated with visual acuity (rs = −0.42, p = 0.014). Cyst growth was not observed. The only complication was an increase in IOP in three (7.7%) patients with multiple cysts. The anatomical location of the cysts cannot differentiate them from solid tumors. The vast majority of cysts are asymptomatic, do not increase in size, and do not require treatment during long-term follow-up.

Anterior Chamber Angle Assessment Techniques: A Review

Assessment of the anterior chamber angle (ACA) is an essential part of the ophthalmological examination. It is intrinsically related to the diagnosis and treatment of glaucoma and has a role in its prevention. Although slit-lamp gonioscopy is considered the gold-standard technique for ACA evaluation, its poor reproducibility and the long learning curve are well-known shortcomings. Several new imaging techniques for angle evaluation have been developed in the recent years. However, whether these instruments may replace or not gonioscopy in everyday clinical practice remains unclear. This review summarizes the last findings in ACA evaluation, focusing on new instruments and their application to the clinical practice. Special attention will be given to the comparison between these new techniques and traditional slit-lamp gonioscopy. Whereas ultrasound biomicroscopy and anterior segment optical coherence tomography provide quantitative measurements of the anterior segment’s structures, new gonio-photographic systems allow for a qualitative assessment of angle findings, similarly to gonioscopy. Recently developed deep learning algorithms provide an automated classification of angle images, aiding physicians in taking faster and more efficient decisions. Despite new imaging techniques made analysis of the ACA more objective and practical, the ideal method for ACA evaluation has still to be determined.

The Effectiveness of Ultrasound Biomicroscopic and Anterior Segment Optical Coherence Tomography in the Assessment of Anterior Segment Tumors: Long-Term Follow-Up

Background

Differential diagnosis and follow-up of small anterior segment tumors constitute a particular challenge because they determine further treatment procedures. The aim of this study was to evaluate the efficacy of the UBM (ultrasound biomicroscopy) and AS-OCT (anterior segment optical coherent tomography) in distinguishing different types of anterior segment lesions.

Methods

It was a retrospective, noncomparative study of case series of 89 patients with the suspicion of anterior segment tumor referred to the Ophthalmology Clinic, Medical University of Białystok, Poland, between 2016 and 2020. UBM was used to assess tumor morphology including height, location, and internal and external features. In cases in which UBM did not provide enough data, the AS-OCT images were analyzed. The data on demographics, best corrected visual acuity (BCVA), intraocular pressure (IOP), and rate of complications were also collected. Patients were followed up from 1 to 48 months.

Results

The mean observation period was 26.61 ± 16.13 months. Among the patients, there were 62 women and 27 men at a mean age of 55.59 ± 19.48 (range: from 20 to 89 years.) The types of tumors were cysts (41%), solid iris tumors (37.1%), ciliary body tumors (7.9%), peripheral anterior synechiae (PAS 3.4%), corneal tumors (4.5%), and others (5.6%). Patients with cysts were younger than patients with solid iris tumor (p=0.002). Women had a cyst as well as solid iris tumor more frequently than men, but less often a ciliary body tumor (p < 0.05). The horizontal size of tumor was positively correlated with patients' age (r_s = 0.38 and p=0.003) and negatively correlated with visual acuity (r_s = −0.42 and p=0.014). During the 4 years of diagnosis, only 2.2% of lesions exhibited growth (growth rate of 0.02 mm per year). Among 15 cases in which visualization with UBM was not satisfactory (mostly iris nevi), AS-OCT was helpful in diagnosis of 13 patients.

Conclusions

Both UBM and AS-OCT are effective methods in detection and diagnosis of tumors of the anterior eye segment, but in some cases, AS-OCT adds additional value to the diagnosis. Many lesions can be managed conservatively because they did not demonstrate growth during 4 years of the follow-up period.

Possible role of standardized echography complementing ultrasound biomicroscopy in tumors of the anterior eye segment: a study in a series of 13 patients

PURPOSE

To evaluate the efficacy of standardized A-scan echography (ASE) complementing ultrasound biomicroscopy (UBM) to propose the most efficient method as grounds for the diagnosis, treatment, and follow-up of anterior eye-segment tumors.

METHODS

The inclusion criteria were tumors of the ciliary body and peripheral choroidal tumors, whose anterior border could not be visualized with a 10 MHz ultrasound probe. The largest basal dimension and the highest prominence of the tumor were measured with a UBM Lin 50 probe. A standardized A-scan examination determined the tumor's thickness and internal reflectivity. Thus, tissue differentiation led to a standardized echography-based diagnosis (SED).

RESULTS

The study included 13 patients. SED was achieved in all examined tumors. The smallest thickness of the tumor of the ciliary body enabling SED was only 1.78 mm. The highest prominence of the tumor (3.66 ± 1.39 mm) was generally larger than its thickness (3.30 ± 1.71 mm).

CONCLUSION

When approaching ciliary body tumors, both ASE and UBM should be performed, the former to accurately differentiate the tumor and measure its height, and the latter to delineate anterior tumor margins and iris involvement. Standardized echography-based diagnosis was grounds for further evaluation and/or treatment in this case series. The highest prominence of the ciliary body tumor perpendicular to the sclera as evidenced by UBM was generally higher than the thickness obtained with standardized echography. Hence, we propose ASE thickness to be the grounds for staging the severity of ciliary body tumors in the algorithm for their management.

Risk Factors Associated with Missed Diagnoses of Narrow Angles by the Van Herick Technique

PURPOSE

To identify which factors are associated with a deep-appearing anterior chamber on slit-lamp examination by the Van Herick (VH) technique in eyes with a diagnosis of narrow angle (NA) on gonioscopy.

DESIGN

Retrospective review.

PARTICIPANTS

One thousand three hundred fourteen eyes in 696 participants with NA on indirect gonioscopy.

METHODS

All included eyes were graded as narrow with iridotrabecular contact on indirect gonioscopy in a darkened room by a single trained glaucoma specialist. Before gonioscopy, eyes were graded as narrow or deep by VH slit-lamp examination technique. Demographic and clinical factors predictive of a deep VH grading were assessed using logistic regression with generalized estimating equations.

MAIN OUTCOME MEASURES

Factors associated with deep versus narrow VH grade.

RESULTS

Using the VH technique, 13.7% of eyes (n = 180/1314) with NA on gonioscopy were classified as deep. Eyes with primary angle-closure glaucoma (PACG; odds ratio, 2.43; P < 0.001) and primary angle closure (PAC; odds ratio, 1.38; P = 0.006) were significantly more likely to be graded as deep by the VH technique relative to eyes that were primary angle-closure suspects (PACSs). In multivariate analysis, male gender (odds ratio, 2.22; P < 0.001), myopia (odds ratio, 1.4; P = 0.048), and black (odds ratio, 4.11; P < 0.001) and Asian (odds ratio, 2.24; P = 0.044) race were independent risk factors for a deep grading with the VH technique in eyes with NA on gonioscopy.

CONCLUSIONS

Patients with NAs on gonioscopy who are men, myopic, and of black or Asian race are at increased risk of being misdiagnosed with deep angles if examined with the VH technique alone. Eyes with PACG and PAC may be more likely than those with PACS to be misdiagnosed as deep with the VH technique. It is possible that by being missed by the VH technique, these eyes could have progressed from PACS to PAC and PACG. Patients with these demographic and clinical characteristics in the presence of other risk factors for glaucoma should undergo careful gonioscopy.

Anterior segment imaging in glaucoma: An updated review

Anterior segment imaging allows for an objective method of visualizing the anterior segment angle. Two of the most commonly used devices for anterior segment imaging include the anterior segment optical coherence tomography (AS-OCT) and the ultrasound biomicroscopy (UBM). AS-OCT technology has several types, including time-domain, swept-source, and spectral-domain-based configurations. We performed a literature search on PubMed for articles containing the text “anterior segment OCT,” “ultrasound biomicroscopy,” and “anterior segment imaging” since 2004, with some pertinent references before 2004 included for completeness. This review compares the advantages and disadvantages of AS-OCT and UBM, and summarizes the most recent literature regarding the importance of these devices in glaucoma diagnosis and management. These devices not only aid in visualization of the angle, but also have important postsurgical applications in bleb and tube imaging.

Anterior segment changes on ultrasound biomicroscopy after intravitreal anti vascular endothelial growth factor injection

BACKGROUND

Intravitreal injections are standard of care today and have the potential to change the anatomy of the anterior segment of the eye. This research was undertaken to evaluate the changes in anterior segment anatomy after intravitreal anti vascular endothelial growth factor (anti VEGF) injections.

METHODS

We conducted a prospective interventional case series at a quaternary care center where patients undergoing intravitreal injection had pre and post injection ultrasound biomicroscopy (UBM) and intraocular pressure (IOP) measurement after intravitreal anti VEGF injection of 0.05 ml volume.

RESULTS

75 eyes of 75 patients as per inclusion criteria were studied. A transient rise in IOP post intravitreal injection was found immediately after the injection. The mean rise from baseline was 17 mmHg immediately after injection and IOP returned to normal within 30 min in all cases. Angle measurement done as per established techniques revealed no significant changes in the angles and anterior chamber.

CONCLUSION

Intravitreal anti VEGF injections had no readily apparent short term concerns. IOP rise was transient and no case was found to have IOP high enough to cause concern for interruption of the optic nerve perfusion or statistically significant narrowing of the anterior chamber angle.

Anterior Chamber Angle Morphometry Measurement Changes to Ambient Illumination Scaling in Visante Time Domain Optical Coherence Tomography

PURPOSE

To test the effect of ambient illumination scaling on the reproducibility and reliability anterior chamber metrics using the Visante time domain optical coherence tomography (TD-OCT) instrument.

MATERIALS AND METHODS

The inferior irido-corneal angles of 25 normal, healthy eyes were imaged twice with the Zeiss Visante TD-OCT under five strictly controlled ambient light conditions (foot candles (fc) measured with a light meter at camera/eye interface). Each eye was imaged 10 times totaling 250 assessments. Angle opening distance (AOD500/750), trabecular iris space area (TISA500/750), and scleral spur (SS) angle were graded twice by masked, trained graders at the Doheny Imaging Reading Center using the Visante's intrinsic tools. Lighting effects on measurements, intra-/inter-grader and acquisition analyses, and Bland-Altman plots were computed using Statistical Package for Social Science (SPSS Inc. version 18.0, Armonk, NY).

RESULTS

With a near linear relationship of angle metrics to lights levels (R² = 0.8-0.95), the analysis examines the differences from the brightest to darkest light levels. Decreasing ambient light levels from 1.0 to 0.0 fc decreased the average AOD500 measurement from 407 ± 136 µm to 315 ± 114 µm (mean percent difference (MPD) 29%, p < 0.001), AOD750 from 587 ± 184 µm to 496 ± 155 µm (MPD 18%, p < 0.001), TISA500 from 136 ± 43 µm² to 101 ± 37 µm² (MPD 35%, p < 0.001), TISA750 from 269 ± 81 µm² to 212 ± 68 µm² (MPD 27%, p < 0.001), and SS angle from 38.3% ± 9% to 32.1% ± 9% (MPD 19%, p < 0.001). Intra-/inter-grader results showed good reproducibility for each grader (MPD = 0.7-3%; coefficient of variation (CV) = 3.2-8.3%; R² = 0.8-0.95; p < 0.001 for all metrics) and between graders (MPD = 1.4-5.9%; CV = 6.7-14.2%; R² = 0.81-0.89; Pearson Correlation Coefficient (PCC) = 0.8-0.97 (p<0.001)). Bland-Altman plots did not demonstrate any apparent bias, with similar repeatability and agreement.

CONCLUSIONS

The results of this study show the high sensitivity of the anterior chamber to changes in the illumination. The slight decrease in light had a corresponding large decrease in Anterior Chamber Angle (ACA) metrics. With clinical diagnoses and treatments of eye diseases relying on these angle measurements, these findings emphasize the importance of strictly controlling light conditions in order to obtain reproducible measurements of anterior chamber geometry.

Assessment of Anterior Segment Changes in Pseudophakic Eyes, Using Ultrasonic Biomicroscopic Imaging, after Pars Plana Vitrectomy with Silicone Oil or Gas Tamponade

Objective. To evaluate the morphological changes of the anterior segment using ultrasonic biomicroscopy (UBM) imaging in pseudophakic patients who underwent pars plana vitrectomy (PPV) with silicone oil or gas (C₃F₈) internal tamponade agent injection. Method. This prospective study included pseudophakic patients with planned PPV, divided into two groups according to internal tamponade agent: those in which silicone oil was used (n = 27, Group 1) and those in which gas (C₃F₈) was used (n = 24, Group 2). UBM measurements were performed in the supine position before and one week after surgery. Results. In patients of Group 1, postoperative trabecular meshwork-ciliary process distance (T-CPD) and iris-ciliary process distance (I-CPD), according to preoperative values, were found to be statistically significantly reduced, and postoperative mean value of scleral thickness (ST) and intraocular pressure (IOP), according to preoperative value, was found to be statistically significantly increased. In patients of Group 2, postoperative mean values of anterior chamber depth (ACD), ciliary body thickness (CBT), T-CPD, I-CPD, and IOP, according to preoperative values, were found to be statistically significantly reduced. Preoperatively, in Group 2 patients, according to Group 1 patients, TIA and IOP were found to be statistically significantly increased. Preoperative and postoperative IOP between the measured parameters with UBM showed no statistically significant correlation. Conclusions. Gases cause more morphological changes in the anterior segment structures. It is thought that complications such as increased intraocular pressure can be seen more frequently for this reason.

Anterior segment analysis and intraocular pressure elevation after penetrating keratoplasty and posterior lamellar endothelial keratoplasty

BACKGROUND

Peripheral anterior synechiae (PAS) is a common problem after penetrating keratoplasty (PK) and leads to intraocular pressure (IOP) elevation. This study examines the risk factors for IOP elevation and post-keratoplasty glaucoma.

METHODS

A retrospective analysis was performed of 47 eyes following PK and of 65 eyes following Descemet's stripping endothelial keratoplasty (DSEK) between 2009 and 2011. The assessment included preoperative history of corneal disease and glaucoma, response to treatment, IOP, and visual acuity. Irido-trabecular contacts (ITC), the angle opening distance (AOD 500) and the anterior chamber angle (ACA 500) were calculated.

RESULTS

The incidences of IOP elevation and post-keratoplasty glaucoma were 27-36% and 10-29%, respectively. The incidence did not differ significantly between both procedures. Pre-existing glaucoma increased the risk for developing IOP elevation and post-DSEK glaucoma. Eyes with bullous keratopathy (BK) developed significantly more IOP elevation (p = 0.01, d.f. = 1, χ(2) = 6.11) and post-keratoplasty glaucoma (p = 0.01, d.f. = 1, χ(2) = 6.22) than eyes with Fuchs' endothelial dystrophy. Eyes with ITC developed post-keratoplasty glaucoma significantly more often than eyes without ITC (p = 0.01, d.f. = 1, χ(2) = 6.63).

CONCLUSION

IOP elevation and post-keratoplasty glaucoma showed a high incidence. Risk factors like pre-existing glaucoma, BK and PAS elevated the rate of IOP elevation and post-keratoplasty glaucoma for both procedures.

Evaluation of anterior chamber angle under dark and light conditions in angle closure glaucoma: An anterior segment OCT study

AIM

To evaluate changes of nasal and temporal anterior chamber angle (ACA) in subjects with angle closure glaucoma using Spectralis AS-OCT (SAS-OCT) under dark and light conditions.

METHODS

Based on dark-room gonioscopy, 24 subjects with open angles and 86 with narrow angles participated in this study. The nasal and temporal angle opening distance at 500 μm anterior to the scleral spur (AOD500), nasal and temporal ACA were measured using SAS-OCT in light and dark conditions.

RESULT

In 2 groups, ACA and AOD500 in nasal and temporal quadrants were significantly greater in light compared to dark (all with p=0.000). The AOD500 and ACA were significantly higher in nasal than temporal in measured conditions for 2 groups except the ACA and AOD500 of normal group measured in light. The difference between nasal and temporal in dark (29.07 ± 65.71 μm for AOD500 and 5.7 ± 4.07° for ACA) was greater than light (24.86 ± 79.85 μm for AOD500 and 2.09 ± 7.21° for ACA) condition. But the difference was only significant for ACA (p=0.000). The correlation analysis showed a negative correlation between AOD500 and pupil diameter in temporal and nasal quadrants (both with p=0.000). While temporal AOD500 difference correlated with spherical equivalent, temporal and asal gonioscopy, nasal AOD correlated with IOP, temporal and nasal gonioscopy.

CONCLUSIONS

Clinically important changes in ACA structure could be detected with SAS-OCT in nasal and temporal quadrants under different illumination intensity. The results could help in improvement of examination condition for better and more accurate assessment of individuals with angle closure glaucoma.

Agreement between Orbscan II, VuMAX UBM and Artemis-2 very-high frequency ultrasound scanner for measurement of anterior chamber depth

Background

The aim was to compare the anterior chamber depth (ACD) measurements taken with Orbscan II, ultrasound biomicroscopy (UBM) and the Artemis-2 VHF (very-high-frequency) ultrasound scanner in normal subjects.

Methods

In this prospective study, one eye from each of 60 normal subjects was randomly selected. Three subjects dropped out of the study because they were apprehensive about the UBM examination; their data were excluded entirely. Measurements of ACD were taken with the Orbscan II, UBM and Artemis-2 VHFUS. Results were obtained for coefficient of variance (CV) and intra-class correlation coefficient (ICC), and statistical analysis was by repeated-measures analysis of variance (ANOVA) for intra-observer repeatability. ANOVA and Bland–Altman analyses were used to determine limits of agreement (LOA) between the three instruments.

Results

The average ACD (± standard deviation) was 3.13 ± 0.34 mm, 2.96 ± 0.27 mm and 2.87 ± 0.31 mm for the Orbscan II, UBM and Artemis-2 VHFUS, respectively. The repeatability scores were 0.015 ± 0.014%, 0.08 ± 0.09% and 0.07 ± 0.06% for the Orbscan II, UBM and Artemis-2 VHFUS, respectively. The ICC for repeatability of Orbscan II, UBM and Artemis-2 VHFUS measurements was high and equal to 0.99%. The intra-observer repeatability scores of the ACD measurement p-values using Orbscan II, UBM and Artemis-2 VHFUS were 0.12, 0.70 and 0.10, respectively. The mean difference and standard deviations for ACD measurements using Orbscan II vs UBM, Orbscan II vs Artemis-2 VHFUS and UBM vs Artemis-2 VHFUS were 0.17 ± 0.31 mm, 0.27 ± 0.34 mm and 0.10 ± 0.18 mm, respectively. LOAs were 0.78 to -0.44 mm, 0.93 to -0.39 mm and 0.45 to -0.26 mm. ANOVA revealed a statistically significant difference between the Orbscan II, UBM and Artemis-2 VHFUS (p < 0.0001).

Conclusions

Measurements by the three instruments show high repeatability. UBM and the Artemis-2 VHFUS can be used interchangeably, but the Orbscan II cannot be used interchangeably with UBM or the Artemis-2 VHFUS.

Morphological analysis of age-related iridocorneal angle changes in normal and glaucomatous cases using anterior segment optical coherence tomography

PURPOSE

To analyze age-related morphological changes of the iridocorneal angle in normal subjects and glaucomatous cases, using anterior segment optical coherence tomography (AS-OCT).

METHODS

This study involved 58 eyes of 58 open-angle glaucoma cases and 72 eyes of 72 age-matched normal-open-angle control subjects. Iridocorneal angle structures in nasal and temporal regions and anterior chamber depth (ACD) were measured using AS-OCT. Axial length and refractive error were measured by use of an ocular biometer and auto refractor keratometer. Angle opening distance (AOD), angle recess area (ARA), and trabecular-iris space area (TISA), measured at 500 μm (TISA500) and 750 μm (TISA750) distant from the scleral spur, were calculated, in the nasal and temporal regions. A new index, the peripheral angle frame index (PAFI), which represents the peripheral angle structure, was proposed, and was defined as (TISA750-TISA500)/TISA500.

RESULTS

Refractive power in the glaucoma cases was less than in control cases (P<0.0001). Axial length (P<0.0001) and ACD (P=0.0004) were longer and deeper, respectively, in the glaucoma cases, compared with the control cases. In both control and glaucoma groups, ACD, AOD, ARA, and TISA decreased linearly in an age-dependent manner, while PAFI stayed at relatively constant values throughout the age distribution. AOD in the glaucoma group was longer than in the control group, in both the temporal and nasal regions; ARA and TISA were larger in the glaucoma than in the control group. However, no significant differences in nasal or temporal PAFI were found between the glaucoma and control groups.

CONCLUSION

The findings of this study show that AS-OCT is useful for the quantitative evaluation of age-related changes in peripheral angle structure in glaucoma and control cases.

Optical coherence tomography and ultrasound biomicroscopy imaging of opaque corneas

PURPOSE

The purpose was to determine the interchangeability of ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT) for corneal opacity depth measurement.

METHODS

Twenty-six eyes of 26 consecutive patients with corneal opacities were examined by both AS-OCT and UBM. The corneal thickness and the corneal opacity depth were measured and compared. The interchangeability was determined by Bland-Altman plotting.

RESULTS

The difference in the full corneal thickness and in the corneal opacity depth between OCT and UBM was 5 ± 7 μm and -1 ± 8 μm, respectively. There were strong correlations and no significant differences between the paired parameters (all r > 0.99, P < 0.01). The limits of agreement were 5 ± 14 μm for the corneal thickness and -1 ± 14.8 μm for the corneal opacity depth.

CONCLUSIONS

AS-OCT and UBM may be used interchangeably for measuring both full corneal thickness and corneal opacity depth in patients with corneal opacity.

Anterior segment biometry using ultrasound biomicroscopy and the Artemis-2 very high frequency ultrasound scanner

Purpose

To compare the precision of anterior chamber angle (ACA) and anterior chamber depth (ACD) measurements taken with ultrasound biomicroscopy (UBM) and the Artemis-2 Very High Frequency Ultrasound Scanner (VHFUS) in normal subjects.

Design

Prospective study.

Methods

We randomly selected one eye from each of 59 normal subjects in this study. Two subjects dropped out of the study; the associated data were excluded from analysis. ACA and ACD measurements were obtained using the VHFUS and the UBM. The results were compared statistically using repeated-measures analysis of variance for the intraobserver repeatability, unpaired t-test, and limits of agreement.

Results

The average ACA values for the UBM and the VHFUS (±standard deviation) were 41.83° ± 5.03° and 33.36° ± 6.03°, respectively. The average ACD values were 2.96 ± 0.34 mm and 2.87 ± 0.31 mm. The intraobserver repeatability analysis of variance P-values for ACA and ACD measurements using UBM were 0.10 and 0.68, respectively; for the Artemis-2 VHFUS, the respective values were 0.68 and 0.09. The difference in ACA measurements was statistically significant (t = 8.41; P < 0.0001), while the difference in ACD values was not (t = 1.51; P < 0.13). The mean ACA difference was 8.50° ± 2.50°, and the limits of agreement were +13.30° to −3.60°. The mean ACD difference was 0.09 ± 0.27 mm, and the limits of agreement ranged from 0.61 mm to −0.43 mm. The mean difference percentage of ACD was 3.1% for both instruments.

Conclusion

In case of the ACD, both instruments can be used interchangeably; however, with the ACA instruments, they cannot be used interchangeably.

The role of anterior segment optical coherence tomography in glaucoma

The anterior segment optical coherence tomography provides an objective method to assess the anterior segment of the eye, including the anatomy of the anterior chamber angle. This technology allows both qualitative and quantitative analyses of the angle and has shown potential in detecting and managing angle-closure glaucoma. In addition, it has a role in identifying pathology in some forms of secondary open-angle glaucoma and postsurgical management of glaucoma. Limitations of this technology include its cost and inability to visualize well structures posterior to the iris, such as the ciliary body. This paper focuses on potential benefits and limitations of anterior segment optical coherence tomography when compared with conventional gonioscopy and ultrasound biomicroscopy. Various clinical entities will be described to discuss its potential role in glaucoma practice.

Comparison of central corneal thickness measurements using ultrasound pachymetry, ultrasound biomicroscopy, and the Artemis-2 VHF scanner in normal eyes

Purpose

To compare the precision of central corneal thickness (CCT) measurements taken with the handheld ultrasound pachymeter (USP), ultrasound biomicroscopy (UBM), and the Artemis-2 very high frequency ultrasound scanner (VHFUS) on normal subjects.

Design

Prospective study.

Methods

One eye from each of 61 normal subjects was randomly selected for this study. The measurements of the CCT were taken with the USP, VHFUS, and UBM. Results were compared statistically using repeated-measures analysis of variance (ANOVA), Pearson’s correlation coefficient, and limits of agreement.

Results

The average CCT (± standard deviation) was 530.1 ± 30.5 μm, 554.9 ± 31.7 μm, and 559.5 ± 30.7 μm for UBM, VHFUS, and USP respectively. The intraobserver repeatability analyses of variance are not significant for USP, UBM, and VHFUS. P-values were 0.17, 0.19, and 0.37 respectively. Repeated-measures ANOVA showed a significant difference between the three different methods of measuring CCT (P = 0.0001). The ANOVA test revealed no statistically significant difference between USP and VHFUS (P > 0.05), yet statistical significant differences with UBM versus USP and UBM versus VHFUS (P < 0.001). There were high correlations between the three instruments (P < 0.0001). The mean differences (and upper/lower limits of agreement) for CCT measurements were 29.4 ± 14.3 (2.7/56), 4.6 ± 8.6 (−14.7/23.8), and −24.8 ± 13.1 (−50.4/0.8) for USP versus UBM, USP versus VHFUS, and UBM versus VHFUS, respectively.

Conclusion

The UBM produces CCT measurements that vary significantly from those returned by the USP and the VHFUS, suggesting that the UBM may not be used interchangeably with either equipment for monitoring the CCT in the clinical setting.

Ultrasound biomicroscopic study of the stability of intraocular lens implants after phacoemulsification cataract surgery

PURPOSE

To assess the postoperative stability of three-piece intraocular lens (IOL) implants using ultrasound biomicroscopy (UBM).

METHODS

This is a prospective observational cohort case series. Best-corrected visual acuity (BCVA) assessment, slit lamp examination, refraction and UBM evaluation were performed preoperatively and at 1, 6, 12, 18 and 24 months postoperatively. The anterior chamber depth (ACD) and IOL tilt angles at the 12, 6, 3 and 9 o'clock meridians were assessed.

RESULTS

Twenty-one consecutive adult patients (21 study eyes) were recruited, but two dropped out from the study. The average age during cataract surgery was 71.7 years (60-83, SD 6.0). There were very slight changes in the refraction and IOL stability characteristics at all the postoperative follow-up time points. These were not found to be statistically significant, apart from the increase in ACD from months one (3.85 ± SD 0.29) to six (3.91 ± SD 0.26) (p = 0.01, paired t-test).

CONCLUSION

There was a small but statistically significant increase in ACD between the first and sixth postoperative month, but ACD remained stable thereafter. This was not associated with any significant changes in refraction or BCVA. In contrast, IOL optic tilt remained statistically unchanged throughout the 24-month study duration.

Ultrasound biomicroscopic assessment of angle parameters in patients with primary angle closure glaucoma undergoing phacoemulsification

PURPOSE

To evaluate the effect of phacoemulsification and foldable intraocular lens (IOL) implantation on biometric determinants of the anterior chamber angle in primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM).

METHODS

Forty-six eyes of 46 patients with chronic PACG and cataract having a patent laser iridotomy were included in this prospective, interventional case series. Angle parameters were measured using UBM before surgery and 3 months after phacoemulsification with IOL implantation. Intraocular pressure (IOP) was measured by applanation tonometer and records of glaucoma medication administered were maintained. Main outcome measures were IOP, central anterior chamber depth (ACD), trabecular iris angle (TIA), and angle opening distance at 250 and 500 µm from scleral spur (AOD250 and AOD500).

RESULTS

The mean age of study participants was 56.5 ± 9.9 years (range 44-75). The preoperative mean IOP was 25.0 ± 5.4 mmHg on maximum antiglaucoma medication, which was reduced to 15.8 ± 3.8 mmHg (p = 0.0001) at 3 months. Number of antiglaucoma medications also decreased from 2.4 ± 1.1 to 0.4 ± 1.1 (p = 0.0001). There was a significant widening of the anterior chamber angle with the TIA increasing significantly after phacoemulsification (p<0.001) with an associated increase in AOD250, AOD500, and ACD (p<0.001).

CONCLUSIONS

Phacoemulsification in eyes with PACG results in significant widening of the anterior chamber angle. This results in better IOP control after surgery and decreases the need for glaucoma medications. These findings are of clinical significance in obviating the need for simultaneous filtering surgery in eyes with PACG undergoing phacoemulsification cataract surgery.

Long-term follow-up of 42 patients with small ciliary body tumors with ultrasound biomicroscopy

PURPOSE

To establish the growth behavior of small ciliary body tumors in a relatively large cohort of patients over an extended period.

DESIGN

Retrospective, noncomparative case series.

METHODS

Ciliary body tumors less than 4 mm in size within the penetration power of ultrasound biomicroscopy (UBM) were included. Tumor height was assessed by ultrasound biomicroscopy. Tumor growth was defined as an increase in height of at least 20% from baseline, as measured on 2 consecutive UBM readings. The data were collected longitudinally, and a statistical analysis was performed.

RESULTS

Forty-two patients were included in the study with a median follow-up of 9.0 years (range, 1.0 to 17.2 years). The median age was 59 years (range, 17 to 82 years). Median initial tumor height was 2.05 mm (range, 1.11 to 3.80 mm). The overall average rate of growth was 0.0014 mm per year (P = .68). The 5- and 10-year accumulative tumor growth rates were 12% and 29%, respectively. In the first 3 years after diagnosis, the growth rate of ciliary body lesions with an initial tumor thickness less than or equal to 2 mm was 0.054 mm per year (P = 0.0001); thereafter, tumor size appeared to stabilize. Tumors with an initial thickness greater than 2 mm showed a small but significant rate of regression of 0.0125 mm per year (P = 0.04).

CONCLUSIONS

Most small tumors of the ciliary body show little growth over an extended period and can be managed conservatively without invasive diagnostic interventions. However, long-term follow-up is required. Indications for treatment include growth in height or lateral extension, extrascleral extension or the need for cataract surgery.

Qualitative assessment of ultrasound biomicroscopic images using standard photographs: the liwan eye study

Objective. To classify anatomic features related to anterior chamber angles by a qualitative assessment system based on ultrasound biomicroscopy (UBM) images. Methods. Cases of primary angle-closure suspect (PACS), defined by pigmented trabecular meshwork that is not visible in two or more quadrants on static gonioscopy (cases) and systematically selected subjects (1 of every 10) who did not meet this criterion (controls) were enrolled during a population-based survey in Guangzhou, China. All subjects underwent UBM examination. A set of standard UBM images was used to qualitatively classify anatomic features related to the angle configuration, including iris thickness, iris convexity, iris angulation, ciliary body size, and ciliary process position. All analysis was conducted on right eye images. Results. Based on the qualitative grades, the difference in overall iris thickness between gonioscopically narrow eyes (n = 117) and control eyes (n = 57) was not statistically significant. The peripheral one third of the iris tended to be thicker in all quadrants of the PACS eyes, although the difference was statistically significant only in the superior quadrant (P = 0.008). No significant differences were found in the qualitative classifications of iris insertion, iris angulation, ciliary body size, and ciliary process position. The findings were similar when compared with the control group of eyes with wide angles in all quadrants. Conclusions. Basal iris thickness seems to be more relevant to narrow angle configuration than to overall iris thickness. Otherwise, the anterior rotation and size of the ciliary body, the iris insertion, and the overall iris thickness are comparable in narrow- and wide-angle eyes.

Anterior chamber parameters measured by the Pentacam CES after uneventful phacoemulsification in normotensive eyes

PURPOSE

We set out to quantify changes in the anterior chamber volume (ACV), anterior chamber depth (ACD) and anterior chamber angle (ACA) measurements obtained by the Pentacam rotating Scheimpflug camera following uneventful phacoemulsification surgery in normotensive eyes with open iridocorneal angles.

METHODS

We enrolled 44 eyes of 44 consecutive patients undergoing cataract extraction in this prospective study. Patients with a history of glaucoma, angle-closure glaucoma or any other concurrent ocular disease were excluded. A detailed eye examination including intraocular pressure (IOP) measurement was performed and ACV, ACD and inferior, superior, temporal and nasal ACA measurements were obtained in each patient eye using the Pentacam Comprehensive Eye Scanner (Pentacam CES) before and 3 months after phacoemulsification and intraocular lens (IOL) implantation with temporal clear corneal incision. Data were compared using paired t-test and one-way anova.

RESULTS

Mean preoperative ACV, ACD, ACA and IOP measurements were 164.7 +/- 49.8 mm(3), 3.0 +/- 0.8 mm, 35.7 +/- 10.2 degrees and 15.8 +/- 3.7 mmHg, respectively. Three months postoperatively, mean ACV, ACD, ACA and IOP measurements were 200.9 +/- 33.3 mm(3), 3.9 +/- 0.9 mm, 41.5 +/- 6.5 degrees and 13.2 +/- 3.9 mmHg, respectively. Postoperative mean ACV, ACD and ACA values in all four quadrants were significantly increased (p < 0.0001, p < 0.0001, p < 0.0001, respectively), whereas IOP was significantly reduced (p < 0.0001).

CONCLUSIONS

The Pentacam CES allowed very easy, fast, automatic and non-contact quantification of the anterior chamber parameters pre- and postoperatively in all patient eyes. Measurements obtained confirm that in normotensive eyes with open iridocorneal angles, the ACV and ACD increase and the ACA widens in all quadrants 3 months after uneventful phacoemulsification and IOL implantation. These changes are accompanied by a significant fall in IOP in the short term.

Prospective comparison of ultrasound biomicroscopy and anterior segment optical coherence tomography for evaluation of anterior chamber dimensions in European eyes with primary angle closure

PURPOSE

To compare the accuracy in measurement of the anterior chamber (AC) angle by anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in European patients with suspected primary angle closure (PACS), primary angle closure (PAC), or primary angle-closure glaucoma (PACG).

DESIGN

Cross-sectional study.

METHODS

In all, 55 eyes of 33 consecutive patients presenting with PACS, PAC, or PACG were examined with AS-OCT, followed by UBM. The trabecular-iris angle (TIA) was measured in all four quadrants. The angle-opening distance (AOD) was measured at 500 microm from the scleral spur. The Bland-Altman method was used for assessing agreement between the two methods.

RESULTS

The mean (+/-SD) superior TIA was 19.3+/-15.8 degrees in AS-OCT and 15.7+/-15.0 degrees in UBM (P=0.50) and inferior TIA was 17.9+/-12.9 degrees (AS-OCT) and 16.7+/-14.1 degrees (UBM) (P=0.71). The superior AOD(500) was 0.17+/-0.16 mm in UBM and 0.21+/-0.16 mm in AS-OCT (P=0.06). Bland-Altman analysis showed a mean SD of+/-9.4 degrees for superior and inferior TIA and a mean SD of +/-0.10 mm for superior and inferior AOD(500).

CONCLUSIONS

This comparative study shows that AS-OCT measurements are significantly correlated with UBM measurements but show poor agreement with each other. We do not believe that AS-OCT can replace UBM for the quantitative assessment of the AC angle.

Laser Peripheral Iridotomy in Eyes with Narrow Drainage Angles: Ultrasound Biomicroscopy Outcomes. The Liwan Eye Study

PURPOSE

To assess the short-term effect of laser peripheral iridotomy (LPI) on anterior segment anatomy in angle-closure suspects using ultrasound biomicroscopy (UBM).

DESIGN

Prospective intervention study.

PARTICIPANTS

Persons identified as angle-closure suspects aged 50-79 years from a population-based survey in Guangzhou, China.

INTERVENTION

Laser peripheral iridotomy was performed on 1 randomly selected eye. Ultrasound biomicroscopy examination was carried out before and 2 weeks after the intervention.

MAIN OUTCOME MEASURES

Proportion of eyes with iridotrabecular contact (ITC), as well as changes in UBM parameters including angle opening distance (AOD), iris thickness (IT), iris curvature, iris ciliary process distance, trabecular-ciliary process distance (TCPD), and scleral spur to iris insertion distance (SS-IR).

RESULTS

A total of 72 of 101 eligible subjects participated in the study. The proportion of people with UBM-identified ITC in > or =1 quadrant dropped from 95% (68/72) before to 59% (42/72) after LPI. After LPI, the mean AOD at 250 microns increased from 0.064 mm (standard deviation [SD], 0.052) to 0.085 (0.052) mm (P<0.001); angle recess area increased from 0.040 (0.030) to 0.070 (0.036) mm2 (P<0.0001); TCPD increased from 0.537 to 0.561 mm (P = 0.001); IT at 750 microns increased from 0.440 to 0.459 mm (P = 0.094), and IT at 1000 microns increased from 0.471 to 0.488 mm (P = 0.0001). Eyes whose angles remained closed after LPI (pigmented trabecular meshwork not visible in > or =3 quadrants) tended to have shallower AOD both at 250 (0.071 vs. 0.049 mm; P = 0.09) and 500 microns (0.108 vs. 0.052 mm; P = 0.001), a thicker iris (IT at 750 microns, 0.447 vs. 0.415 mm; P = 0.041), a more anterior positioned ciliary body (TCPD, 0.514 vs. 0.562 mm; P = 0.03), and a statistically nonsignificant more anterior iris insertion (SS-IR: 0.085 vs. 0.125 mm; P = 0.061), before LPI.

CONCLUSIONS

Laser peripheral iridotomy results in a significant increase in the angle width in Chinese people with narrow angles. However, some iridotrabecular contact was found in 59% of eyes with a patent iridotomy. This was associated with smaller anterior chamber angle dimensions and a thicker iris, both of which may play a causative role in maintaining angle closure after LPI.

Repeatability and reproducibility of anterior chamber angle measurement with anterior segment optical coherence tomography

AIM

To evaluate the repeatability and reproducibility of anterior chamber angle measurement obtained by anterior segment optical coherence tomography.

METHODS

Twenty-five normal subjects were invited for anterior chamber angle imaging with an anterior segment optical coherence tomography (OCT) on one randomly selected eye in three separate visits within a week. Each eye was imaged three times under room light (light intensity = 368 lux) and three times in the dark during the first visit. In the subsequent visits, each eye was imaged once in the light and once in the dark. The angle opening distance (AOD 500) and the trabecular-iris angle (TIA 500) were measured by a single observer. Only the nasal angle was analysed. Intrasession and intersession within-subject standard deviation (Sw), precision (1.96xSw), coefficient of variation (CVw) (100xSw/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility.

RESULTS

For intrasession repeatability, the Sw, precision, CVw and ICC of AOD/TIA were 45 microm/2.4 degrees , 88 microm/4.7 degrees , 5.8%/4.8% and 0.97/0.95 in the light; and 45 microm/2.1 degrees , 88 microm/4.2 degrees , 7.0%/5.0% and 0.98/0.97 in the dark. For intersession reproducibility, the Sw, precision, CVw and ICC of AOD/TIA were 79 microm/3.5 degrees , 155 microm/6.8 degrees , 10.0%/7.0%, 0.91/0.89 in the light; and 64 microm/3.4 degrees , 124 microm/6.6 degrees , 9.9%/7.8% and 0.95/0.92 in the dark.

CONCLUSIONS

The anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions with good repeatability and reproducibility.

Recent advances in ophthalmic anterior segment imaging: a new era for ophthalmic diagnosis?

Anterior segment imaging is a rapidly advancing field of ophthalmology. New imaging modalities, such as rotating Scheimpflug imaging (Pentacam-Scheimpflug) and anterior segment optical coherence tomography (Visante OCT and Slit-Lamp OCT), have recently become commercially available. These new modalities supplement the more established imaging devices of Orbscan scanning slit topography and ultrasound biomicroscopy (UBM). All devices promise quantitative information and qualitative imaging of the cornea and anterior chamber. They provide a quantitative angle estimation by calculating the angle between the iris surface and the posterior corneal surface. Direct angle visualisation is possible with the OCT devices and UBM; they provide images of the scleral spur, ciliary body, ciliary sulcus and even canal of Schlemm in some eyes. Pentacam-Scheimpflug can measure net corneal power, a feature particularly useful for cataract patients having undergone previous corneal surgery. Anterior segment OCT can measure corneal flap depth following LASIK and anterior chamber width prior to phakic intraocular lens implantation. The arrival of the new imaging devices may herald the dawn of a new era for ophthalmic diagnosis, particularly in view of the ease and non-contact nature of examination.

Ultrasound biomicroscopy of the upper eyelid structures in normal eyelids

PURPOSE

To evaluate the normal upper eyelid structures quantitatively and qualitatively using ultrasound biomicroscopy (UBM).

METHODS

Sixteen upper eyelids of 16 healthy subjects with no eyelid problems were evaluated with UBM. The orbicularis oculi muscle, levator aponeurosis, Müller muscle-conjunctival complex, and tarsus were imaged centrally just above the tarsus, and the tarsus was imaged just above the eyelid margin. The thickness of these structures was measured primary gaze. The measurements of levator aponeurosis and Müller muscle-conjunctival complex were repeated in upgaze.

RESULTS

Of 16 patients, 8 were men and 8 were women. Eight were more than 40 years old and eight were younger. Orbicularis oculi muscle and Müller muscle-conjunctival complex were echo-dense, while levator aponeurosis and tarsus were echo-lucent. The mean thickness was 0.74 +/- 0.11 mm for orbicularis oculi muscle, 0.44 +/- 0.67 mm for levator aponeurosis, 0.91 +/- 0.15 mm for tarsus, and 0.38 +/- 0.64 mm for Müller muscle-conjunctival complex. There was no significant difference in the thickness of these structures between the patients younger than 40 years old and older patients, or between male and female patients (p > 0.05). In upgaze, the increases in thickness of levator aponeurosis and Müller muscle-conjunctival complex were a mean of 53% and 32%, respectively.

CONCLUSIONS

UBM is an easy, non-invasive test used to visualize normal eyelid structures. It can be used in the diagnosis and follow-up of eyelid problems. The normal upper eyelid structures showed no significant differences based on age or gender.

Advances in anterior segment imaging

PURPOSE OF REVIEW

Imaging of the crystalline lens and intraocular lens is becoming increasingly more important to optimize the refractive outcome of cataract surgery, to detect and manage complications and to ascertain advanced intraocular lens performance. This review examines recent advances in anterior segment imaging.

RECENT FINDINGS

The main techniques used for imaging the anterior segment are slit-lamp biomicroscopy, ultrasound biomicroscopy, scheimpflug imaging, phakometry, optical coherence tomography and magnetic resonance imaging. They have principally been applied to the assessment of intraocular lens centration, tilt, position relative to the iris and movement with ciliary body contraction.

SUMMARY

Despite the advances in anterior chamber imaging technology, there is still the need for a clinical, high-resolution, true anatomical, noninvasive technique to image behind the peripheral iris.

Small ciliary body tumors: ultrasound biomicroscopic assessment and follow-up of 42 patients

PURPOSE

Detecting and following small tumors of the ciliary body is a particular challenge because of their location. Recently high-frequency ultrasound biomicroscopy (UBM) has been used to assist in this task. The aim of this study was to evaluate this subset of small ciliary body tumors through the use of UBM.

DESIGN

Retrospective, noncomparative case series.

METHODS

Forty-two patients with small ciliary body tumors (less than 4 mm) from our institution were included in the study with a median follow-up of 4.3 years. UBM was used to assess tumor characteristics including height, location, and internal and external features. The data were collected longitudinally, and statistical analysis was performed.

RESULTS

Median initial tumor height was 2.05 mm (range 1.1 to 3.8 mm) as measured by UBM. By 5 years after diagnosis, five tumors (12%) exhibited growth. The overall mean growth rate was 0.026 mm per year (P = .00007). The most rapid period of growth was in the first year after diagnosis (growth rate 0.128 mm per year), after which the mean tumor size appeared to stabilize.

CONCLUSIONS

UBM is a valuable tool for detecting and following small ciliary body tumors (less than 4 mm), as these lesions may go undetected by other methods. Despite the potential for local extension into the iris or choroid, few of the tumors in this study exhibited growth, suggesting that many of these tumors can be managed conservatively. UBM can be used to assess various internal tumor features; however, arriving at a specific diagnosis without histologic correlation is difficult.