Imaging of the anterior segment in glaucoma

Lens factor as an underlying mechanism in primary angle closure with gonioscopically-visualized ciliary body processes

PURPOSE

To compare the differences in anterior segment parameters between eyes with primary angle closure (PAC) with and without gonioscopically-visualized ciliary body processes (CBP).

STUDY DESIGN

Prospective, observational, comparative clinical study.

METHODS

Detailed ocular examinations and gonioscopy were performed in 89 eyes of 89 patients with PAC to determine the visibility of the CBP. Anterior chamber depth (ACD), anterior chamber width, lens thickness (LT), lens vault (LV) and pupil diameter were determined using ultrasound biomicroscopy. The lens-axial length factor (LAF) and relative lens position (RLP) were calculated. All parameters were compared between eyes with and without gonioscopically visible CBP (PAC+CBP and PAC-CBP groups) after adjusting for age and gender. The association of the parameters with visible CBP was analyzed by univariate logistic regression analysis.

RESULTS

PAC+CBP group included 41 eyes and the PAC-CBP group, 48 eyes. The axial length and ACD were statistically significantly smaller (p = 0.009 and p = 0.005, respectively) and LT, LV and LAF were statistically significantly greater (p = 0.03, p = 0.008 and p = 0.004, respectively) in the PAC+CBP group. In the PAC eyes with glaucoma, the LT, LV and LAF were statistically significantly greater in the PAC+CBP group (p = 0.02, p = 0.001 and p = 0.02, respectively). The LAF had the strongest association with visible CBP in the regression analysis (Odds ratio = 141.70, p = 0.002).

CONCLUSION

Gonioscopical visualization of ciliary processes may suggest that anterior segment crowding, especially lens factor is the underlying mechanism in PAC. It may provide a practical gonioscopic examination method for predicting the predominant pathophysiology of PAC.

Advancements in high-resolution imaging of the iridocorneal angle

High-resolution imaging methods of the iridocorneal angle (ICA) will lead to enhanced understanding of aqueous humor outflow mechanisms and a characterization of the trabecular meshwork (TM) morphology at the cellular level will help to better understand glaucoma mechanics (e.g., cellular level biomechanics of the particulate glaucomas). This information will translate into immense clinical value, leading to more informed and customized treatment selection, and improved monitoring of procedural interventions that lower intraocular pressure (IOP). Given ICA anatomy, imaging modalities that yield intrinsic optical sectioning or 3D imaging capability will be useful to aid in the visualization of TM layers. This minireview examines advancements in imaging the ICA in high-resolution.

Preventing blindness from glaucoma with patient education, the NIDEK GS-1 Gonioscope, lensectomy and microinvasive glaucoma surgery

OBJECTIVES

The purpose of this report is to demonstrate the patient education ability and benefits in treating glaucoma and preventing blindness with the NIDEK GS-1 Gonioscope and earlier surgical intervention with cataract surgery/lensectomy and microinvasive glaucoma surgery (MIGS).

METHODS

This data was collected using a NIDEK GS-1 Gonioscope. Informed consent was obtained from all participants following explanation of possible risks.

RESULTS AND DISCUSSION

NIDEK GS-1 automated gonioscopy offers many advantages, including (1) the ability to capture high quality, 360-degree chromatic documentation of the iridocorneal angle and trabecular meshwork, (2) improved patient education on the condition at hand through images; and (3) visualization of the change in the angle and trabecular meshwork before and after surgical intervention in patients with glaucoma.

CONCLUSION AND IMPLICATIONS

Gonioscopic imaging is helpful in educating patients on the anatomy of the angle and how its anatomical configuration can contribute to glaucoma. It also gives clinicians a supplementary tool to document features of the ICA; to evaluate anatomical changes before and after surgical treatment of glaucoma and cataracts; and to demonstrate to patients how a specific surgical device or technique is controlling their intraocular pressure (IOP).

Classifications of Qualitative Characteristics on Angle Configurations via Ultrasound Biomicroscopy in Acute Primary Angle Closure

Purpose

To study the classifications of qualitative characteristics on the angle configurations in the acute primary angle closure (APAC) and fellow eyes by ultrasound biomicroscopy (UBM).

Methods

A total of 131 patients (262 eyes) were researched retrospectively. The qualitative parameters from UBM images were classified into iris form (IF), ciliary body configuration (CBC), basal iris thickness (BIT), iris convexity (IC), iris insert (II), iris angulation (IA), ciliary body size (CBS) and ciliary body position (CBP). Comparative analyses between the APAC (case group) and fellow (control group) eyes were performed.

Results

There were significant differences in IF, CBC, IC, II, CBS, CBP between the case group and control group in all quadrants (P<0.001). The IA of the case group and control group presented significant difference in all quadrants (P=0.001). However, there was not a significant difference in BIT between the case group and control group in all quadrants (P=0.495). The case group had fewer parallelogram-like and mushroom-like and more cone-like and hook-like CBCs than the control group (P<0.001).

Conclusion

Multiple ciliary body configurations can influence the stability of the lens and the anatomic configuration of the anterior chamber angle indirectly. New qualitative classification system of UBM may be more intuitionistic and refined to reflect the angle configurations to help clinical practice.

Automated Focal Plane Merging From a Stack of Gonioscopic Photographs Using a Focus-Stacking Algorithm

Purpose

The purpose of this study was to investigate the utility of automated focal plane merging with the collection of gonio-photographs with different depths of field (DOF) using an established focus-stacking algorithm.

Methods

A cross-sectional study was conducted at Shimane University Hospital, Izumo, Japan. Sixteen eyes from 16 subjects from the glaucoma clinic were included in this study. Image processing was performed for the images of 16 eyes from 16 angle sector following the successful gonio-photography. The 256 sets of focus-stacked and best-focused images were prepared in random order and were compared for the DOF and informativeness to diagnose angle pathology by masked observers in each set as the subjective assessments. Moreover, the energy of the Laplacian (average |ΔI|), which is an indicator of image sharpness between the photographs with and without the focus-stacking processing was also analyzed with the Laplacian filter as the objective assessment.

Results

The automated image processing was successfully performed in all stacks of images. The significant deepening of DOF and improvement of informativeness achieved in 255 (99.6%) and 216 (84.4%) images (P < 0.0001 for both, sign test) and the energy of the Laplacian also significantly increased in 243 (94.9%) images (P < 0.0001, sign test).

Conclusions

Focal plane merging by the automated algorithm can make the gonio-images deeper focus compared with the paired best-focused images subjectively and objectively, which would be useful for angle pathological assessment in clinical practice.

Translational Relevance

Focal plane merging algorithm for the automated gonio-photography can facilitate the angle assessment by providing informative deep-focus image, which would be useful for glaucoma care.

Anterior Lens Curvature Matters in the Course of Primary Angle Closure: An Analysis Based on Ultrasound Biomicroscopic Imaging

Purpose. To evaluate the effect of anterior lens curvature in primary angle closure (PAC) and find additional anatomical features of crystalline lens that may predispose primary angle closure to the acute course. Methods. 435 eyes (263 subjects) were enrolled in this study. Four groups of eyes were included based on angle configurations and clinical features: (i) acute primary angle closure (APAC, 140 eyes); (ii) chronic primary angle closure (CPAC, 116 eyes); (iii) primary angle closure suspect (PACS, 84 eyes); and (iv) normal controls (95 eyes). All patients underwent thorough ophthalmic exams including applanation tonometry, gonioscopy, low-coherence interferometry, and ultrasound biomicroscopic imaging. Based on the panoramic anterior segment images from ultrasound biomicroscopic imaging measurements, the radius of anterior lens curvature (ALR) was calculated using the least-squares curve fitting technique. ALR, in addition to axial length (AL), anterior chamber depth (ACD), and lens thickness (LT), was compared among different groups using univariate and multivariate analysis with mixed effects linear model. Results. APAC, CPAC, and PACS groups all had steeper ALR, shorter AL, shallower ACD, and thicker LT than normal control group. ACD and LT further differ between APAC and CPAC or PACS eyes. Moreover, a steeper ALR was also found in the APAC group as compared to CPAC, PACS, and normal control groups. Conclusions. A steeper ALR may predispose the acute attack of PAC. In addition to the relative lens position and size, lens curvature is another variable that contributes to the pathophysiological mechanisms of primary angle closure.

Comparison of Ocular Morphological Parameters Related to Lens Position by Anterior Segment Optical Coherence Tomography and Ultrasound Biomicroscopy

OBJECTIVE

The objective is to compare parameters related to lens position measured using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in patients with senile cataract and perform a consistency analysis.

METHODS

This prospective study included 102 patients (102 eyes) scheduled for simple cataract surgery. Among the total patients, 44 were men, and 58 were women. AS-OCT (sitting) and UBM (lying) were used to measure the anterior chamber depth (ACD) in horizontal and vertical orientations and the iris-lens contact distance (ILCD) and iris-lens angle (ILA) in inferior, superior, nasal, and temporal quadrants. Paired-sample t-test was used to compare ACD, ILCD, and ILA measurements of the two methods, while Pearson's linear correlation and Bland-Altman analyses were used to analyze the correlation and consistency of the two results.

RESULTS

The horizontal (2.499 ± 0.464 mm) and vertical (2.531 ± 0.463 mm) ACD measured using AS-OCT and the horizontal (2.556 ± 0.467 mm) and vertical (2.563 ± 0.479 mm) ACD measured using UBM were significantly different (P < 0.001); moreover, the results showed good correlation and agreement. A significant difference was observed between the two methods in terms of ILCD measured in inferior, superior, nasal, and temporal quadrants (P < 0.001), and a significant correlation was found between measurements of both methods (P < 0.001). Approximately 3.92% (4/102), 0.98% (1/102), 3.92% (4/102), and 2.94% (3/102) of points were outside the 95% limits of agreement in the four quadrants, respectively, and the agreement of the results was good. ILA measured using both methods differed in inferior, superior, nasal, and temporal quadrants (P=0.003, 0.011, 0.001, 0.001, respectively), and the correlation was good (P < 0.001). The percentage of points outside the 95% limit was higher in inferior, superior, nasal, and temporal quadrants (4.90% (5/102), 5.88% (6/102), 5.88% (6/102), and 6.86% (7/102)) with poor agreement of the results.

CONCLUSIONS

The correlation between AS-OCT and UBM in terms of measuring lens position-related parameters was good, but the agreement was unstable. The differences in measurement position (sitting and supine) and/or measurement methods (optics and ultrasound) may lead to variability in results.

Intraobserver and interobserver agreement among anterior chamber angle evaluations using automated 360-degree gonio-photos

Purpose

To investigate the reproducibility for the iridocorneal angle evaluations using the pictures obtained by a gonioscopic camera, Gonioscope GS-1 (Nidek Co., Gamagori, Japan).

Methods

The pragmatic within-patient comparative diagnostic evaluations for 140 GS-1 gonio-images obtained from 35 eyes of 35 patients at four ocular sectors (superior, temporal, inferior, and nasal angles) were conducted by five independent ophthalmologists including three glaucoma specialists in a masked fashion twice, 1 week apart. We undertook the observer agreement and correlation analyses of Scheie’s angle width and pigmentation gradings and detection of peripheral anterior synechia and Sampaolesi line.

Results

The respective Fleiss’ kappa values for the four elements between manual gonioscopy and automated gonioscope by the glaucoma specialist were 0.22, 0.40, 0.32 and 0.58. Additionally, the respective intraobserver agreements for the four elements by the glaucoma specialist each were 0.32 to 0.65, 0.24 to 0.71, 0.35 to 0.70, and 0.20 to 0.76; the Fleiss’ kappa coefficients for the four elements among the three glaucoma specialists were, respectively, 0.31, 0.38, 0.31, and 0.17; the Fleiss’ kappa coefficients for the angle width and pigmentation gradings between the two glaucoma specialists each were 0.30 to 0.35, and 0.29 to 0.43, respectively. Overall, the Kendall’s tau coefficients for the angle gradings reflected the positive correlations in the evaluations.

Conclusion

Our findings suggested slight-to-substantial intraobserver agreement and slight-to-fair (among the three) or fair-to-moderate (between the two each) interobserver agreement for the angle assessments using GS-1 gonio-photos even by glaucoma specialists. Sufficient training and a solid consensus should allow us to perform more reliable angle assessments using gonio-photos with high reproducibility.

Exploring the Occurrence Mechanisms of Acute Primary Angle Closure by Comparative Analysis of Ultrasound Biomicroscopic Data of the Attack and Fellow Eyes

Purpose

To explore the anatomical characteristics and occurrence mechanisms of acute primary angle closure (APAC) by comparing the quantitative data of UBM images of the APAC and fellow eyes.

Methods

131 patients (262 eyes) were studied over five years by retrospective analysis. The quantitative data from UBM images including angle opening distance at 500 μm (AOD500), trabecular-iris angle (TIA), iris convexity (IC), iris span (IS), iris-lens angle (ILA), iris-lens contact distance (ILCD), iris-ciliary process angle (ICPA), and limbus-ciliary body angle (LCBA) were retrospectively recorded; comparative analysis of the APAC and fellow eyes was performed.

Results

The superior, inferior, nasal, temporal, and mean AOD500, TIA, IC, and LCBA (P < 0.001) were significantly smaller in APAC than in fellow eyes. Values of the lens thickness (LT), lens/axial length factor (LAF), lens position (LP), and relative lens position (RLP) were lower in APAC than in fellow eyes (P = 0.021; P = 0.025; P < 0.001; and P < 0.001). In APAC eyes, AOD500 was significantly positively correlated with IC, ILCD, and LCBA; TIA was significantly positively significantly correlated with IC, ILCD, and LCBA. In fellow eyes, AOD500 was significantly negatively correlated with ILA and significantly positively correlated with ILCD, ICPA, LCBA, axial length (AL), central anterior chamber depth (CACD), and LP; TIA was significantly negatively correlated with ILA and significantly positively correlated with IS, ILCD, ICPA, LCBA, AL, CACD, LP, and RLP.

Conclusions

Multiple nonpupillary block factors (plateau iris, anterior attachment and insertion of the iris root, anterior shift of the lens, and anterior rotation of the ciliary body) promote the occurrence of APAC, and abnormal positional relationships of the iris, ciliary body, and lens may contribute to APAC.

Automated anterior chamber angle pigmentation analyses using 360° gonioscopy

Purpose

To assess the pigmentation distribution in the iridocorneal angle using an established algorithm with gonioscopically obtained images.

Methods

Manual and automatically modified Scheie’s pigmentation grading (ie, 0/I=0, II=1 and III/IV=2) of trabecular meshwork was performed using an established algorithm on the 75 open-angle eyes of 75 subjects obtained by automated gonioscopy. All images were collected at the Matsue Red Cross Hospital in 2016. The differences in the pigmentation density were compared statistically between the automated and manual techniques and among the four sectors (ie, inferior, superior, temporal and nasal) and the four quadrants.

Results

There was substantial agreement between both grading methods (kappa value=0.70). There was no significant difference between the automated and manual grading in any sectors except for the superior (p=0.0004). The automated pigmentation grade was significantly (p<0.05) higher in the inferior sector (mean grade, 1.43) than in the others (mean grade, 0.48~0.76), and it was also significantly (p<0.05) higher in the inferior quadrant (mean grade, 3.56) than in the others (mean grade, 1.64~2.24). The findings were similar for manual grading.

Conclusions

The entire distribution of the pigmentation in the anterior chamber angle was classified successfully using the algorithm, and the automated versus manual grading comparison showed good agreement. The automated pigmentation grading scores in the inferior sector and inferior quadrant were significantly higher than in the others as previously reported. Similar findings also were seen for manual grading.

Characteristic Manifestations regarding Ultrasound Biomicroscopy Morphological Data in the Diagnosis of Acute Angle Closure Secondary to Lens Subluxation

Purpose

To investigate the mechanisms underlying the occurrence of acute angle closure (AAC) and to further explore the sensitive indicators for clinical diagnosis of acute angle closure secondary to lens subluxation (AACSLS) through qualitative and quantitative analysis of ultrasound biomicroscopy (UBM) imaging features of eyes with AAC to provide a theoretical basis for the selection of treatment schemes.

Methods

A retrospective analysis was conducted from 2013 to 2018 on 160 eyes (160 patients) with uniocular acute angle closure crisis (AACC) complicated by cataract. The case group consisted of 29 eyes (29 patients) with lens subluxation and the control group consisted of 131 eyes (131 patients) without lens subluxation. Before the operation, computer optometry, best corrected visual acuity, intraocular pressure, slit lamp, gonioscopy, preset lens, A-mode ultrasonography, and UBM were performed. All the enrolled subjects underwent cataract surgery with or without other operations. The pupil was fully dilated, and the position of the lens was recorded before the operation. The zonular rupture and lens subluxation were further confirmed during operation. SPSS version 20.0 was used to analyze UBM imaging data from the lens subluxation group and non-lens subluxation group.

Results

The iris span (IS) value in the whole quadrant of the lens subluxation group was significantly higher than that of the non-lens subluxation group (P=0.033, 95%CI 0.01 to 0.31). The iris lens angle (ILA) in the lens subluxation group was significantly lower than that in the non-lens subluxation group in the upper, lower, nasal, temporal, and whole quadrants (P<0.001, 95%CI -8.79 to -2.78; P=0.001, 95%CI -8.36 to -2.27; P<0.001, 95%CI -9.85 to -4.98; P=0.015, 95%CI -6.67 to -0.72; P<0.001, 95%CI -8.74 to -5.83, respectively). However, the ILA of the maximum difference among the four quadrants in the lens subluxation group was significantly higher than that in the non-lens subluxation group (P<0.001, 95%CI 4.74 to 9.86). The ILA and iris lens contact distance (ILCD) showed significant negative correlations in both the lens subluxation group and non-lens subluxation group (Y=20.984-7.251X, R=0.520, and P<0.001; Y=19.923-3.491X, R=0.256, and P<0.001, respectively). The risk ratio of lens subluxation in exposed eyes with ILA=0 in one quadrant at least was significantly higher than that in nonexposed eyes without ILA=0 in all quadrants (X²=87.859, P<0.001, and odds ratio (OR)=79.200, 95% CI 23.063 to 271.983). The risk ratio of zonular rupture in exposed quadrants with ILA=0 was significantly lower than that in nonexposed eyes without ILA=0 (X²=33.884, P<0.001, OR=0.122, and 95% CI 0.053 to 0.278). The risk ratio of zonular rupture in exposed quadrants with nonforward convexity of iris was significantly lower than that in nonexposed quadrants with forward convexity of iris (X²=6.413, P=0.011, and OR=0.381; 95% CI 0.176 to 0.825).

Conclusions

ILA=0 and nonforward convexity of iris as UBM sensitive and characteristic indicators for screening lens subluxation and zonular rupture can provide new ideas and hints for clinical diagnosis of acute angle closure secondary to lens subluxation.

A Population-Based Assessment of the Agreement Between Grading of Goniophotographic Images and Gonioscopy in the Chinese-American Eye Study (CHES)

Purpose

To compare grading of goniophotographic images and gonioscopy in assessing the iridocorneal angle.

Methods

In a population-based, cross-sectional study, participants underwent gonioscopy and goniophotographic imaging during the same visit. The iridocorneal angle was classified as closed if the posterior trabecular meshwork could not be seen. A single masked observer graded the goniophotographic images, and each eye was classified as having angle closure based on the number of closed quadrants. Agreement between the methods was analyzed by calculating kappa (κ) and first-order agreement coefficient (AC1) statistics and comparison of area under receiver operating characteristic curves (AUC).

Results

A total of 4149 Chinese Americans (3994 eyes) were included in this study. The agreement for angle closure diagnosis between gonioscopy and EyeCam was moderate to excellent (κ = 0.60, AC1 0.90, AUC 0.76–0.80).

Conclusions

Detection of iridocorneal angle closure based on goniophotographic imaging shows moderate to very good agreement with angle closure assessment using gonioscopy.

Ageing and ocular surface immunity

Foreword

It gives me pleasure to introduce the 4th edition of the EGS Guidelines. The Third edition proved to be extremely successful, being translated into 7 languages with over 70000 copies being distributed across Europe; it has been downloadable, free, as a pdf file for the past 4 years. As one of the main objectives of the European Glaucoma Society has been to both educate and standardize glaucoma practice within the EU, these guidelines were structured so as to play their part.

Glaucoma is a living specialty, with new ideas on causation, mechanisms and treatments constantly appearing. As a number of years have passed since the publication of the last edition, changes in some if not all of these ideas would be expected.

For this new edition of the guidelines a number of editorial teams were created, each with responsibility for an area within the specialty; updating where necessary, introducing new diagrams and Flowcharts and ensuring that references were up to date. Each team had writers previously involved with the last edition as well as newer and younger members being co-opted.

As soon as specific sections were completed they had further editorial comment to ensure cross referencing and style continuity with other sections.

Overall guidance was the responsibility of Anders Heijl and Carlo Traverso. Tribute must be made to the Task Force whose efforts made the timely publication of the new edition possible.

Roger Hitchings

Chairman of the EGS Foundation

www.eugs.org

The Guidelines Writers and Contributors 

Augusto Azuara Blanco

Luca Bagnasco

Alessandro Bagnis

Keith Barton

Christoph Baudouin

Boel Bengtsson

Alain Bron

Francesca Cordeiro

Barbara Cvenkel

Philippe Denis

Christoph Faschinger

Panayiota Founti

Stefano Gandolfi

David Garway Heath

Francisco Goni

Franz Grehn

Anders Heijl

Roger Hitchings

Gabor Hollo

Tony Hommer

Michele Iester

Jost Jonas

Yves Lachkar

Giorgio Marchini

Frances Meier Gibbons

Stefano Miglior

Marta Misiuk-Hojo

Maria Musolino

Jean Philippe Nordmann

Norbert Pfeiffer

Luis Abegao Pinto

Luca Rossetti

John Salmon

Leo Schmetterer

Riccardo Scotto

Tarek Shaarawy

Ingeborg Stalmans

Gordana Sunaric Megevand

Ernst Tamm

John Thygesen

Fotis Topouzis

Carlo Enrico Traverso

Anja Tuulonen

Ananth Viswanathan

Thierry Zeyen

The Guidelines Task Force 

Luca Bagnasco

Anders Heijl

Carlo Enrico Traverso

Augusto Azuara Blanco

Alessandro Bagnis

David Garway Heath

Michele Iester

Yves Lachkar

Ingeborg Stalmans

Gordana Sunaric Mégevand

Fotis Topouzis

Anja Tuulonen

Ananth Viswanathan

The EGS Executive Committee 

Carlo Enrico Traverso (President)

Anja Tuulonen (Vice President)

Roger Hitchings (Past President)

Anton Hommer (Treasurer)

Barbara Cvenkel

Julian Garcia Feijoo

David Garway Heath

Norbert Pfeiffer

Ingeborg Stalmans

The Board of the European Glaucoma Society Foundation 

Roger Hitchings (Chair)

Carlo E. Traverso (Vice Chair)

Franz Grehn

Anders Heijl

John Thygesen

Fotis Topouzis

Thierry Zeyen

The EGS Committees 

CME and Certification 

Gordana Sunaric Mégevand (Chair)

Carlo Enrico Traverso (Co-chair)

Delivery of Care 

Anton Hommer (Chair)

EU Action 

Thierry Zeyen (Chair)

Carlo E. Traverso (Co-chair)

Education 

John Thygesen (Chair)

Fotis Topouzis (Co-chair)

Glaucogene 

Ananth Viswanathan (Chair)

Fotis Topouzis (Co-chair)

Industry Liaison 

Roger Hitchings (Chair)

Information Technology 

Ingeborg Stalmans (Chair)

Carlo E. Traverso (Co-chair)

National Society Liaison 

Anders Heijl (Chair)

Program Planning 

Fotis Topouzis (Chair)

Ingeborg Stalmans (Co-chair)

Quality and Outcomes 

Anja Tuulonen (Chair)

Augusto Azuara Blanco (Co-chair)

Scientific 

Franz Grehn (Chair)

David Garway Heath (Co-chair)

Role of Optical Coherence Tomography in Assessing Anterior Chamber Angles

INTRODUCTION

Gonioscopy is the gold standard in assessing anterior chamber angles. However, interobserver variations are common and there is a need for reliable objective method of assessment.

AIM

To compare the anterior chamber angle by gonioscopy and Spectral Domain Optical Coherence Tomography (SD-OCT) in individuals with shallow anterior chamber.

MATERIALS AND METHODS

This comparative observational study was conducted in a rural tertiary multi-speciality teaching hospital. A total of 101 eyes of 54 patients with shallow anterior chamber on slit lamp evaluation were included. Anterior chamber angle was graded by gonioscopy using the shaffer grading system. Angles were also assessed by SD-OCT with Trabecular Iris Angle (TIA) and Angle Opening Distance (AOD). Chi-square test, sensitivity, specificity, positive and negative predictive value to find correlation between OCT parameters and gonioscopy grading.

RESULTS

Females represented 72.7%. The mean age was 53.93 ±8.24 years and mean anterior chamber depth was 2.47 ± 0.152 mm. Shaffer grade ≤ 2 were identified in 95(94%) superior, 42(41.5%) inferior, 65(64.3%) nasal and 57(56.4%) temporal quadrants. Cut-off values of TIA ≤ 22° and AOD ≤ 290 μm were taken as narrow angles on SD-OCT. TIA of ≤ 22° were found in 88(92.6%) nasal and 87(87%) temporal angles. AOD of ≤ 290 μm was found in 73(76.8%) nasal and 83(83%) temporal quadrants. Sensitivity in detecting narrow angles was 90.7% and 82.2% for TIA and AOD, while specificity was 11.7% and 23.4%, respectively.

CONCLUSION

Individuals were found to have narrow angles more with SD-OCT. Sensitivity was high and specificity was low in detecting narrow angles compared to gonioscopy, making it an unreliable tool for screening.

Repeatability and comparison of clinical techniques for anterior chamber angle assessment

PURPOSE

To assess the repeatability of gonioscopy, van Herick method and anterior segment Optical Coherence Tomography (AS-OCT) and determine the agreement between these techniques within a community optometry setting.

METHODS

Gonioscopy, van Herick method and AS-OCT imaging were performed by an optometrist on two occasions, 1 month apart, on 80 subjects aged over 40 years recruited from community optometry practices. Anterior segment images were captured with a spectral domain OCT (Topcon 3D OCT-2000; wavelength 840 nm) set to the Anterior Segment (AS) mode. Eyes were graded as open or occludable for each method. AS-OCT images from both visits were graded by a second optometrist masked to the gonioscopy and van Herick method results, and the visit on which the images were acquired. Cohen's kappa (κ) was used to describe the intra-observer repeatability. Likelihood ratios, sensitivity and specificity of van Herick method and AS-OCT were calculated, using gonioscopy as the reference standard.

RESULTS

Measurements were obtained from 80 eyes of 80 subjects. In four cases, AS-OCT images were un-gradable due to difficulty in locating the scleral spur. The repeatability of gonioscopy was fair κ = 0.29, while that of the van Herick method (κ = 0.54) and AS-OCT (κ = 0.47) were somewhat better. The van Herick method showed good sensitivity (visit 1: 75%, visit 2: 69%) and high specificity (visit 1: 88%, visit 2: 96%). The sensitivity of AS-OCT was fair (visit 1: 46%, visit 2: 25%), but specificity was high (visit 1: 87%. visit 2: 89%).

CONCLUSION

Intra-observer repeatability was better for van Herick method and for AS-OCT than for gonioscopy, despite the latter being considered the gold standard method. The van Herick method appeared to be more sensitive than AS-OCT when identifying eyes at risk of angle closure. A standalone anterior segment OCT with a longer wavelength laser could afford better visualisation of the angle, and might therefore be expected to enable the examiner to make more precise classifications. These instruments are not widely used by optometrists in clinical practice in the UK at present.

Optimal number of angle images for calculating anterior angle volume and iris volume measurements

PURPOSE

We determined the optimal number of angle images required to obtain reliable measurements of trabecular-iris circumferential volume (TICV) and iris volume (IV) using swept-source Fourier domain anterior segment optical coherence tomography (SSFD-ASOCT) scans in narrow angle eyes.

METHODS

Scleral spur landmarks (SSL) were manually identified on ASOCT angle images from 128 meridians from each of 24 eyes with chronic primary angle closure (PAC) spectrum of disease. The anterior and posterior corneal curves, and the anterior and posterior iris surfaces were identified automatically by the anterior chamber analysis and interpretation (ACAI) software, then manually examined and edited by the reader if required. Trabecular-iris circumferential volume at 750 μm from SSL (TICV750) and IV were subsequently calculated using varying numbers of angle images. Threshold error was determined to be less than the lower 95% confidence limit of mean absolute percent error (MAPE) of the change in TICV or IV resulting from laser peripheral iridotomy, which would be 17% for TICV and 5% for IV, based on previous studies. The optimal number of angle images was the smallest number of images where MAPE was less than this threshold for TICV and IV.

RESULTS

A total of 32 equally-spaced angle images (16 meridians) was required to estimate TICV750 and 16 angle images (8 meridians) to estimate IV. Both were within 4.6% and 1.6% of MAPE, respectively.

CONCLUSIONS

It is possible to determine TICV and IV parameters reliably in narrow angles without evaluating all 128 meridians obtained with SSFD-ASOCT.

A novel method for quantifying the amount of trabecular meshwork pigment in glaucomatous and nonglaucomatous eyes

PURPOSE

To assess the use of a computerized program for evaluating the amount of trabecular meshwork (TM) pigmentation in normal (control), primary open-angle glaucoma (POAG), and pseudoexfoliation glaucoma/pigmentary dispersion glaucoma (PXFG/PDG) patients.

METHODS

All included patients were from the Goldschleger Eye Institute glaucoma clinic. After signing an informed consent, each patient's anterior chamber angle was photographed using a single photo-slit under the same conditions. Only one eye per patient was photographed. The superior TM and the inferior TM were documented. Then, the degree of "blackness" (representing melanin pigment) was assessed using the ImageJ program.

RESULTS

Of the 43 eyes photographed, 8 were excluded because of low-quality images. Of the remaining 35 patients, 14 were normal, 10 had POAG, and 11 had PXFG/PDG. The amount of pigment was the same in the control and the POAG patients whether the inferior TM (P=0.24), superior TM (P=0.58), or the sum inferior TM+superior TM (P=0.85) was measured. The pigment level was significantly higher in the PXFG/PDG group than in the control group (inferior TM, P<0.01; superior TM, P=0.047; sum, P<0.01). The difference between the inferior and the superior TM pigment levels was found to be statistically insignificant in all the groups (normal, P=0.86; POAG, P=0.10; PXFG/PDG, P=0.22).

CONCLUSIONS

The use of ImageJ software might play a role in the quantification of pigment evaluation of the TM.

Age-related changes in trabecular meshwork imaging

PURPOSE

To evaluate the normal aging effects on trabecular meshwork (TM) parameters using Fourier domain anterior segment optical coherence tomography (ASOCT) images.

PATIENTS AND METHODS

One eye from 45 participants with open angles was imaged. Two independent readers measured TM area, TM length, and area and length of the TM interface shadow from 3 age groups (18-40, 41-60, and 61-80). Measurements were compared using stepwise regression analysis.

RESULTS

The average TM parameters were 0.0487 (± 0.0092) mm(2) for TM area, 0.5502 (± 0.1033) mm for TM length, 0.1623 (± 0.341) mm(2) for TM interface shadow area, and 0.7755 (± 0.1574) mm for TM interface shadow length. Interobserver reproducibility coefficients ranged from 0.45 (TM length) to 0.82 (TM area). TM area and length were not correlated with age. While the TM interface shadow length did not correlate with age, the TM interface shadow area increased with age. Race, sex, intraocular pressure, and gonioscopy score were not correlated with any TM parameters.

CONCLUSION

Although the TM measurements were not correlated with age, the TM interface shadow area increased with age. Further study is required to determine whether there is any relationship between the age-related ASOCT findings of the TM interface shadow area and physiologic function.

Ultrasound biomicroscopic evaluation of anterior segment cysts as a risk factor for ocular hypertension and closure angle glaucoma

AIM

To investigate the relationship between the ultrasound biomicroscopic (UBM) features of anterior-segment cysts (ASCs) and increased intraocular pressure (IOP) as a risk factor for closed-angle glaucoma (CAG).

METHODS

Totally 24 eyes with recently diagnosed ASCs were divided into two groups. First group with ASC and ocular normotension (n=13), second group with ASC and ocular hypertension (n=11). An ophthalmologic examination, including tonometry, slit-lamp biomicroscopy (SLBM), gonioscopy, fundoscopy, pentacam, and UBM, was performed. The features of the ASCs were compared with the IOP.

RESULTS

ASCs were accurately diagnosed and delineated in 24 eyes using UBM. IOP was elevated in those ASCs with a secondary aetiology (P=0.027), iridociliary location (P=0.006), deformed shape (P=0.013), increased size (P=0.001) and elongated pupillary aperture (P=0.009). However, the count (P=0.343) of ASCs, anterior chamber depth (ACD; P=0.22) and axial lenght (AL; P=0.31) were not associated with ocular hypertension. Correlations were found between the IOP and ASC size (r=-0.712; P=0.003), anterior chamber angle (ACA; r=-0.985; P<0.001), angle opening area (AOA; r=0.885; P<0.001), angulation of iris (r=-0.776, P<0.001), and affected iris quadrant (r =-0.655, P=0.002).

CONCLUSION

Ocular hypertension in some eyes with ASC might be associated with various mechanisms, including secondary aetiology, iridociliary location, deformed shape, increased size and elongated pupill, which can be determined by UBM.

Evaluation of secondary glaucoma associated with subluxated lens misdiagnosed as acute primary angle-closure glaucoma

PURPOSE

To evaluate the causes of misdiagnosis in patients with acute angle-closure glaucoma secondary to subluxated lens, and postoperative outcomes.

DESIGN

Retrospective clinical study.

METHODS

Five hundred twenty-six cases of acute angle-closure glaucoma were consecutively recruited from Zhongshan Ophthalmic Center between March 2003 and March 2009. Zonular dialysis, anterior chamber angle, and anterior chamber depth were examined by ultrasound biomicroscopy. Surgical therapy was performed according to the degree of zonular dialysis and angle closure.

RESULTS

Thirty-one eyes (5.89%) with acute angle-closure glaucoma secondary to lens subluxation were misdiagnosed as acute primary angle-closure glaucoma. In these cases, the anterior chamber depth of the affected eyes was significantly shallower than the fellow eyes (1.34±0.45 vs. 2.27±0.44, P<0.05). The best-corrected visual acuity was significantly improved 3 months after surgery, and intraocular pressure was well controlled in all eyes. Mean intraocular pressure was 12.09±4.41 mm Hg without any medication at the final visit.

CONCLUSIONS

The causes of misdiagnosis in patients with acute angle-closure glaucoma secondary to subluxated lens include neglected history and/or signs of ocular trauma. Lens extraction surgery was an effective therapy for these cases.

The complementary benefit of anterior segment optical coherence tomography in penetrating keratoplasty

PURPOSE

To evaluate the utility of anterior segment optical coherence tomography (AS-OCT) assessment in the pre- and postsurgical management of full-thickness corneal grafts.

METHODS

Seventy eyes of 58 patients who had penetrating keratoplasty were included in the study. High resolution AS-OCT scans of the cornea and the anterior segment were performed before and after transplantation in 17 eyes with the Visante™ optical coherence tomography. Fifty-three eyes were examined in the late postoperative period.

RESULTS

The mean follow-up was 4.3 years (range, 1-15 years). Six different graft-host junctions were identified. Three patients with graft rejection, four patients with anterior synechia, and three patients with corneal ulcer were evaluated. Preoperative evaluation of eyes with semiopaque and totally opaque corneas revealed important information about anterior segment structures additional to slit-lamp findings.

CONCLUSION

AS-OCT is a useful complementary tool for the evaluation of penetrating corneal transplantation surgery and in the management of its postoperative complications.

Five-year incidence of angle closure among glaucoma health examination participants

BACKGROUND AND AIM

To investigate incidence of angle closure (AC) and its associated factors through a community-based longitudinal study over a 5-year period.

METHODS

Japanese residents aged 40 years or over who underwent two glaucoma health examinations held in 2005 and 2010 were enrolled. Of the participants of the first glaucoma health examination (first examination), those who satisfied exclusion criteria such as having eyes with angle closure, glaucoma, incisional ocular surgery, or other conditions that could influence the results were eliminated from the second glaucoma health examination (second examination). In addition to routine ophthalmic examination, a scanning peripheral anterior chamber depth analyzer (SPAC) was employed to investigate the anterior chamber configuration. The incidence of angle closure over the 5-year period and its associated factors were investigated.

RESULTS

Of the 754 participants of the first examination, 569 participants were invited for the second examination and 331 participants (87 males and 244 females, age: 62.6 ± 12.7 years), or 619 eyes, were analyzed after eliminating eyes matching exclusion criteria. In the 5-year period, the incidence of AC was 5.4 % (95 % CI: 3.5-8.4 %) of participants or 5.5 % (95 % CI: 4.0-7.6 %) of eyes, including eight eyes (1.3 %) with primary angle-closure glaucoma. Eyes that developed AC had a much smaller SPAC grade at the first examination and a greater decrease in SPAC grade than those that did not develop AC, whereas age and sex were not associated.

CONCLUSIONS

AC was developed by 5.4 % of senior Japanese residents over the 5-year period. The shallow anterior chamber and the marked decrease in anterior chamber depth were associated with AC development.

Comparing approaches to screening for angle closure in older Chinese adults

AIMS

Primary angle-closure glaucoma is expected to account for nearly 50% of bilateral glaucoma blindness by 2020. This study was conducted to assess the performance of the scanning peripheral anterior chamber depth analyzer (SPAC) and limbal anterior chamber depth (LACD) as screening methods for angle closure.

METHODS

This study assessed two clinical populations to compare SPAC, LACD, and gonioscopy: the Zhongshan Angle-closure Prevention Trial, from which 370 patients were eligible as closed-angle participants and the Liwan Eye Study, from which 72 patients were selected as open-angle controls. Eligible participants were assessed by SPAC, LACD, and gonioscopy.

RESULTS

Angle status was defined by gonioscopy. Area under the receiver operating characteristic curve (AUROC) for SPAC was 0.92 (0.89-0.95) whereas AUROC for LACD was 0.94 (0.92-0.97). Using conventional cutoff points, sensitivity/specificity was 93.0%/70.8% for SPAC and 94.1%/87.5% for LACD. Sequential testing using both SPAC and LACD increased the specificity to 94.4% and decreased the sensitivity to 87.0%.

CONCLUSION

SPAC has significantly lower specificity than LACD measurement using conventional cutoffs but interpretation of the findings can be performed by modestly trained personnel.