Gonioscopy with corneal indentation. A method for distinguishing between appositional closure and synechial closure

A Survey of Current Gonioscopy Practice in the United Kingdom

PRCIS

This survey highlights a deficiency in gonioscopy practices across the UK, particularly in the utilization of indentation gonioscopy and training of junior ophthalmologists. Recommendations include standardizing practice and enhancing training opportunities to improve patient care.

OBJECTIVE

Gonioscopy is an important general skill learned and practiced by all grades of ophthalmologists. The aim of this study is to discover the general attitude, perception, and practice of gonioscopy among ophthalmologists in the UK.

MATERIALS AND METHODS

A National gonioscopy survey was carried out by utilizing an anonymous electronic questionnaire of 18 questions. The questionnaire was electronically distributed online, using the survey tool, Microsoft 2016 "MS Forms" to all grades of ophthalmologists in the UK.

RESULTS

A total of 146 responses were analyzed. Overall, 89% of the participants felt "comfortable in performing slit lamp gonioscopy," but only 38% of junior trainees (ophthalmic specialist trainees years 1-3) felt comfortable in gonioscopy. Only 13% of the junior trainees felt they had adequate training in performing gonioscopy compared with 68% of the total respondents. Surprisingly, the majority of consultants (58%) did not "strongly agree" to be confident in assessing the angle and its configuration on gonioscopy. The most commonly used gonioscopic lens in this survey was the Zeiss four-mirror gonio lens, but only 38% of participants performed indentation gonioscopy routinely. The majority of the participants utilized the modified Shaffer's classification for gonioscopy. Fewer than expected numbers performed gonioscopy routinely for new patients with glaucoma.

CONCLUSION

This survey suggests that gonioscopy is not being performed according to the UK national recommendations, and few ophthalmologists perform indentation gonioscopy. Additional gonioscopy training in the curriculum may be helpful.

Diagnostic performance of anterior segment optical coherence tomography in detecting plateau iris

Objective

To evaluate the diagnostic performance of manual grading of anterior segment optical coherence tomography (AS-OCT) in detection of plateau iris configuration (PIC) based on the presence of standardised ultrasound biomicroscopy (UBM) criteria in at least two quadrants; namely, clinical diagnosis of PIC (DxPIC).

Methods and analysis

In this cross-sectional study, paired AS-OCT and UBM images were evaluated by three glaucoma specialists. AS-OCT was classified into two mechanisms, PIC versus non-PIC, of primary angle closure disease (PACD) and AS-OCT-PIC diagnostic performance was tested with DxPIC.

Results

One hundred and seventy-nine eyes of 142 patients were enrolled for analysis, and DxPIC was found in 85 eyes (47.49%). Intraobserver agreement rates of AS-OCT classification by the graders were 0.77, 0.701 and 0.742 (all p<0.001), and interobserver agreement rates, between a senior glaucoma specialist and the other two glaucoma specialists, were 0.68 and 0.702 (all p<0.001). Plateau iris was classified in AS-OCT images by the three graders, rated 32.96%–39.1% and 24.58%–34.08% in the horizontal and vertical axes, respectively. Diagnostic performance was analysed, yielding sensitivity ranging from 56.47% to 77.78%, and specificity of 48.94% to 64.29%. We applied disease prevalence of 30%, revealing positive predictive values varying from 32.16% to 44.44%, and negative predictive values of 72.4% to 85.71%. Accuracy ranged from 51.2% to 65%. Agreement between the two devices was fair, kappa range 0.31–0.351.

Conclusion

Performance of manual grading of AS-OCT in detection of DxPIC was relatively poor; therefore, unadjusted AS-OCT does not appear to be good for manual PIC screening in PACD patients and cannot serve as a substitute for UBM in PIC detection.

Digital Gonioscopy Based on Three-dimensional Anterior-Segment OCT: An International Multicenter Study

PURPOSE

To develop and evaluate the performance of a 3-dimensional (3D) deep-learning-based automated digital gonioscopy system (DGS) in detecting 2 major characteristics in eyes with suspected primary angle-closure glaucoma (PACG): (1) narrow iridocorneal angles (static gonioscopy, Task I) and (2) peripheral anterior synechiae (PAS) (dynamic gonioscopy, Task II) on OCT scans.

DESIGN

International, cross-sectional, multicenter study.

PARTICIPANTS

A total of 1.112 million images of 8694 volume scans (2294 patients) from 3 centers were included in this study (Task I, training/internal validation/external testing: 4515, 1101, and 2222 volume scans, respectively; Task II, training/internal validation/external testing: 378, 376, and 102 volume scans, respectively).

METHODS

For Task I, a narrow angle was defined as an eye in which the posterior pigmented trabecular meshwork was not visible in more than 180° without indentation in the primary position captured in the dark room from the scans. For Task II, PAS was defined as the adhesion of the iris to the trabecular meshwork. The diagnostic performance of the 3D DGS was evaluated in both tasks with gonioscopic records as reference.

MAIN OUTCOME MEASURES

The area under the curve (AUC), sensitivity, and specificity of the 3D DGS were calculated.

RESULTS

In Task I, 29.4% of patients had a narrow angle. The AUC, sensitivity, and specificity of 3D DGS on the external testing datasets were 0.943 (0.933-0.953), 0.867 (0.838-0.895), and 0.878 (0.859-0.896), respectively. For Task II, 13.8% of patients had PAS. The AUC, sensitivity, and specificity of 3D DGS were 0.902 (0.818-0.985), 0.900 (0.714-1.000), and 0.890 (0.841-0.938), respectively, on the external testing set at quadrant level following normal clinical practice; and 0.885 (0.836-0.933), 0.912 (0.816-1.000), and 0.700 (0.660-0.741), respectively, on the external testing set at clock-hour level.

CONCLUSIONS

The 3D DGS is effective in detecting eyes with suspected PACG. It has the potential to be used widely in the primary eye care community for screening of subjects at high risk of developing PACG.

A Deep Learning System for Automatic Assessment of Anterior Chamber Angle in Ultrasound Biomicroscopy Images

Purpose

To develop and assess a deep learning system that automatically detects angle closure and quantitatively measures angle parameters from ultrasound biomicroscopy (UBM) images using a deep learning algorithm.

Methods

A total of 3788 UBM images (2146 open angle and 1642 angle closure) from 1483 patients were collected. We developed a convolutional neural network (CNN) based on the InceptionV3 network for automatic classification of angle closure and open angle. For nonclosed images, we developed a CNN based on the EfficienttNetB3 network for the automatic localization of the scleral spur and the angle recess; then, the Unet network was used to segment the anterior chamber angle (ACA) tissue automatically. Based on the results of the latter two processes, we developed an algorithm to automatically measure the trabecular-iris angle (TIA500 and TIA750), angle-opening distance (AOD500 and AOD750), and angle recess area (ARA500 and ARA750) for quantitative evaluation of angle width.

Results

Using manual labeling as the reference standard, the ACA classification network's accuracy reached 98.18%, and the sensitivity and specificity for angle closure reached 98.74% and 97.44%, respectively. The deep learning system realized the automatic measurement of the angle parameters, and the mean of differences was generally small between automatic measurement and manual measurement. The coefficients of variation of TIA500, TIA750, AOD500, AOD750, ARA500, and ARA750 measured by the deep learning system were 5.77%, 4.67%, 10.76%, 7.71%, 16.77%, and 12.70%, respectively. The within-subject standard deviations of TIA500, TIA750, AOD500, AOD750, ARA500, and ARA750 were 5.77 degrees, 4.56 degrees, 155.92 µm, 147.51 µm, 0.10 mm², and 0.12 mm², respectively. The intraclass correlation coefficients of all the angle parameters were greater than 0.935.

Conclusions

The deep learning system can effectively and accurately evaluate the ACA automatically based on fully automated analysis of a UBM image.

Translational Relevance

The present work suggests that the deep learning system described here could automatically detect angle closure and quantitatively measure angle parameters from UBM images and enhancing the intelligent diagnosis and management of primary angle-closure glaucoma.

Identification of peripheral anterior synechia with anterior segment optical coherence tomography

PURPOSE

To generate a model that evaluates the presence and extent of peripheral anterior synechia (PAS) based on anterior segment optical coherence tomography (AS-OCT).

METHODS

The extent of PAS involvement in the eyes of patients with angle closure was assessed by indentation gonioscopy, and the part of non-PAS and PAS were assigned into two groups (NPAS and PAS). Anterior chamber angles were then imaged by AS-OCT with light-emitting diode (LED) irradiation directly into the pupils, leading to pupillary constriction and increasing anterior chamber angle width. Parameters including the angle opening distance at 750 μm anterior to the scleral spur (AOD750) and trabecular-iris space area at 750 μm anterior to the scleral spur (TISA750) were then obtained. The differences before and after LED irradiation of AOD750 and TISA750 were calculated and used to generate a PAS model based on binary logistic regression. Validation data were then tested.

RESULTS

A total of 258 AS-OCT images in 14 eyes were assigned to the modeling data, and 120 were assigned to the validation data. There were no differences in AOD750 and TISA750 in the dark between NPAS and PAS (P_AOD750 = 0.258, P_TISA750 = 0.486), whereas after LED light exposure, TISA750_light was larger in NPAS than in PAS (P = 0.047). The light-dark differences of both parameters showed significant differences between the two groups (P_AOD750dif = 0.019, P_TISA750dif < 0.001). The area under the curve of the model performance was 0.841, and the overall correct rate was 80.8% based on the validation data.

CONCLUSIONS

The present study demonstrates that the AS-OCT-based PAS model could be useful in the identifying of the presence of synechial angle closure and evaluating the extent of PAS in a single eye.

Anterior Chamber Angle Evaluation Using Gonioscopy: Consistency and Agreement between Optometrists and Ophthalmologists

SIGNIFICANCE

In our intermediate-tier glaucoma care clinic, we demonstrate fair to moderate agreement in gonioscopy examination between optometrists and ophthalmologists, but excellent agreement when considering open versus closed angles. We highlight the need for increased consistency in the evaluation and recording of angle status using gonioscopy.

PURPOSE

The consistency of gonioscopy results obtained by different clinicians is not known but is important in moving toward practice modalities such as telemedicine and collaborative care clinics. The purpose of this study was to evaluate the description and concordance of gonioscopy results among different practitioners.

METHODS

The medical records of 101 patients seen within a collaborative care glaucoma clinic who had undergone gonioscopic assessment by two clinicians (one optometrist and either one general ophthalmologist [n = 50] or one glaucoma specialist [n = 51]) were reviewed. The gonioscopy records were evaluated for their descriptions of deepest structure seen, trabecular pigmentation, iris configuration, and other features. These were compared between clinicians (optometrist vs. ophthalmologist) and against the final diagnosis.

RESULTS

Overall, 51.9 and 59.8% of angles were graded identically in terms of deepest visible structure when comparing between optometrist versus general ophthalmologist and optometrist versus glaucoma specialist, respectively. The concordance increased when considering ±1 of the grade (67.4 and 78.5%, respectively), and agreement with the final diagnosis was high (>90%). Variations in angle grading other than naming structures were observed (2.0, 30, and 3.9% for optometrist, general ophthalmologist, and glaucoma specialist, respectively). Most of the time, trabecular pigmentation or iris configuration was not described.

CONCLUSIONS

Fair to moderate concordance in gonioscopy was achieved between optometrists and ophthalmologists in a collaborative care clinic in which there is consistent feedback and clinical review. To move toward unified medical records and a telemedicine model, improved consistency of record keeping and angle description is required.

To Study the Efficacy of Laser Peripheral Iridoplasty in the Treatment of Eyes With Primary Angle Closure and Plateau Iris Syndrome, Unresponsive to Laser Peripheral Iridotomy, Using Anterior-Segment OCT as a Tool

PURPOSE

To use anterior-segment optical coherence tomography (AS-OCT) as a tool to monitor the outcome of iridoplasty in patients with primary angle closure (PAC) and plateau iris syndrome (PIS), who were unresponsive to a previous laser peripheral iridotomy.

MATERIALS AND METHODS

This was a prospective, observational case control study. Patients diagnosed with PAC and PIS who had undergone laser peripheral iridotomy earlier, but were unresponsive to the procedure, were subjected to an iridoplasty. The intraocular pressure (IOP) and anterior-chamber parameters were measured before and after the procedure, and complications were noted. The patients were followed up for 1 year, and results were analyzed.

RESULTS

Twenty-four eyes of 12 patients underwent the iridoplasty procedure. Sixteen eyes were diagnosed as cases of PAC and 8 eyes were diagnosed as cases of PIS. Main outcome measures were the IOP, peripheral anterior synechiae, AS-OCT angle parameters, and complications. After iridoplasty, there was a significant decrease in the IOP from 24.4±5.6 to 16.5±5.4 mm Hg (P<0.001) at the final follow-up. The mean number of antiglaucoma medications decreased from 1.6±0.9 to 0.7±1.1. The medians of the peripheral anterior synechiae extent reduced from 3.5 (quartile range, 1.5 to 6.0) to 2.0 (quartile range, 0.5 to 4.0) clock hours in the PAC group (P<0.001) and from 3.8 (quartile range, 2.0 to 6.5) to 2.5 (quartile range, 0.8 to 5.0) clock hours in the PIS group (P<0.001). Changes in AS-OCT parameters noted were as follows: the AOD500 increased from 0.132±0.016 to 0.179±0.062 mm (P<0.001), TISA500 from 0.085±0.012 to 0.104±0.051 mm (P<0.001), and scleral spur angle from 19.5±2.4 to 26.8±4.5 degrees (P<0.001). No significant changes in the angle-to-angle distance and the crystalline lens rise were found.

CONCLUSIONS

In eyes with synechial angle closure and PIS that do not show an improvement after an iridotomy, laser peripheral iridoplasty can be very effective. There were no significant complications after the iridoplasty procedure, implying that it is quite safe. This study also demonstrates that AS-OCT can serve as a useful tool to document the preprocedure angle parameters, to note the changes after the procedure, and for the long-term follow-up of these patients.

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)

Angle assessment by EyeCam, goniophotography, and gonioscopy

PURPOSE

To compare EyeCam (Clarity Medical Systems, Pleasanton, CA) and goniophotography in detecting angle closure, using gonioscopy as the reference standard.

METHODS

In this hospital-based, prospective, cross-sectional study, participants underwent gonioscopy by a single observer, and EyeCam imaging and goniophotography by different operators. The anterior chamber angle in a quadrant was classified as closed if the posterior trabecular meshwork could not be seen. A masked observer categorized the eyes as per the number of closed quadrants, and an eye was classified as having angle closure if there were 2 or more quadrants of closure. Agreement between the methods was analyzed by κ statistic and comparison of area under receiver operating characteristic curves (AUC).

RESULTS

Eighty-five participants (85 eyes) were included, the majority of whom were Chinese. Angle closure was detected in 38 eyes (45%) with gonioscopy, 40 eyes (47%) using EyeCam, and 40 eyes (47%) with goniophotography (P=0.69 in both comparisons, McNemar test). The agreement for angle closure diagnosis (by eye) between gonioscopy and the 2 imaging modalities was high (κ=0.86; 95% Confidence Interval (CI), 0.75-0.97), whereas the agreement between EyeCam and goniophotography was not as good (κ=0.72; 95% CI, 0.57-0.87); largely due to lack of agreement in the nasal and temporal quadrants (κ=0.55 to 0.67). The AUC for detecting eyes with gonioscopic angle closure was similar for goniophotography and EyeCam (AUC 0.93, sensitivity=94.7%, specificity=91.5%; P>0.95).

CONCLUSIONS

EyeCam and goniophotography have similarly high sensitivity and specificity for the detection of gonioscopic angle closure.

Increased iris-lens contact following spontaneous blinking: mathematical modeling

The purpose of this work was to study in silico how iris root rotation due to spontaneous blinking alters the iris contour. An axisymmetric finite-element model of the anterior segment was developed that included changes in the iris contour and the aqueous humor flow. The model geometry was based on average values of ocular dimensions. Blinking was modeled by rotating the iris root posteriorly and returning it back to the anterior. Simulations with maximum rotations of 2°, 4°, 6°, and 8° were performed. The iris-lens contact distance and the pressure difference between the posterior and anterior chambers were calculated. When the peak iris root rotation was 2°, the maximum iris-lens contact increased gradually from 0.28 to 0.34mm within eight blinks. When the iris root was rotated by 6° and 8°, the pressure difference between the posterior and anterior chambers dropped from a positive value (1.23Pa) to negative values (-0.86 and -1.93Pa) indicating the presence of reverse pupillary block. Apparent iris-lens contact increased with steady blinking, and the increase became more pronounced as posterior rotation increased. We conclude that repeated iris root rotation caused by blinking could maintain the iris in a posterior position under normal circumstances, which would then lead to the clinically observed anterior drift of the iris when blinking is prevented.

Angle imaging: advances and challenges

Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.

A history of gonioscopy

The first view of the iridocorneal angle in a living human occurred accidentally in the late 1800s. Lenses were first used to see the angle in 1914, but practical gonioscopy would not come into existence for many years as the slitlamp and lenses that could be used at the slitlamp were developed. This article reviews the history of gonioscopy.

Reverse pupillary block slows iris contour recovery from corneoscleral indentation

Corneoscleral indentation changes the iris contour and alters the angle between the iris and cornea. Although this effect has long been observed, the mechanism by which it occurs remains poorly understood. Previous theoretical research has shown that corneoscleral indentation can deform the eye globe and consequently rotate the iris root. In this work, we studied the fluid-structure interaction between the iris and aqueous humor, driven by iris root rotation. The iris root rotation obtained from our previous whole-globe model was used as a boundary condition for a fluid-structure interaction finite element model of the anterior eye. We studied the effect of two parameters-rotation angle and indentation speed-on the iris contour and aqueous humor dynamics. We found that posterior rotation of the iris root caused posterior bowing of the iris. After the iris root was returned to its original orientation, the aqueous humor was trapped in the anterior chamber because the iris tip pinned against the lens (reverse pupillary block). After 0.5-2 min of simulation, aqueous humor secretion into the posterior chamber and outflow from the anterior chamber allowed the system to return to its original steady state flow condition. The faster or farther the iris root rotated, the longer it took to return to steady state. Reverse pupillary block following corneoscleral indentation is a possible explanation for the clinical observation that prevention of blinking causes the iris to drift forward.

Gonioscopy in primary angle closure glaucoma

Primary angle closure is a condition characterized by obstruction to aqueous humor outflow by the peripheral iris, and results in changes in the iridocorneal angle that are visible through gonioscopic examination. Gonioscopy in these eyes, however, can be difficult. This chapter discusses techniques that might help in the examination. These include beginning the examination with the inferior angle, methods to help in looking over the iris, cycloplegia, locating the corneal wedge, indentation, van Herick estimation, examining the other eye, and topical glycerin. Finally, there is a discussion about the pathology associated with the closed angle, with emphasis on the appearance of iris bombé, plateau iris, and the distinction between iris processes and peripheral anterior synechiae.

Corneal indentation in the early management of acute angle closure

PURPOSE

To describe in detail corneal indentation (CI) in the management of a series of patients treated for acute angle closure (AAC).

DESIGN

Retrospective, consecutive, noncomparative case series.

PARTICIPANTS

Seven consecutive patients (8 eyes) referred to the authors with the diagnosis of AAC. Patients presented to the Prince of Wales Hospital, Randwick, or to the private practices of the authors.

INTERVENTION

Seven patients (8 eyes) underwent CI as part of their early management for AAC.

MAIN OUTCOME MEASURES

Reduction in intraocular pressure (IOP), symptoms of AAC and pain relief.

RESULTS

Of the 7 patients, complete data were available for 6. The IOP was significantly reduced (P<0.05) and 3 of 4 patients with severe acute pain reported early resolution of pain after CI. The average reduction in IOP was 20.9 mmHg (range +1 to -45). All patients subsequently underwent definitive management with laser peripheral iridotomies or lensectomy using phacoemulsification. Three patients treated acutely with CI without any medical agents had a mean IOP reduction of 21 mmHg (range, 20-23) after indentation.

CONCLUSIONS

Corneal indentation is a rapid, portable, and effective method of reducing elevated IOP in the setting of AAC. It can be performed with instrumentation that is readily at hand and allows for rapid pain relief. This reduction in IOP improves corneal clarity and permits further definitive management of the patient with AAC.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Evaluation and Comparison of Indentation Ultrasound Biomicroscopy Gonioscopy in Relative Pupillary Block, Peripheral Anterior Synechia, and Plateau Iris Configuration

PURPOSE

To evaluate and compare the findings and changes of the anterior chamber angle configuration with indentation ultrasound biomicroscopy (UBM) gonioscopy in relative pupillary block (RPB), peripheral anterior synechia (PAS), and plateau iris configuration (PIC).

METHODS

This study included 73 eyes of 52 patients with RPB (n = 26), PAS (n = 21), or PIC (n = 26). First, a conventional UBM scan was performed using a normal size standard eye cup before indentation. Then, for indentation UBM gonioscopy, scans were performed using a new eye cup that we designed. For evaluation of the angle, angle opening distance 500 and angle recess area were recorded and evaluated with regard to the effect of expansion on the anterior chamber angle.

RESULTS

Indentation UBM gonioscopy showed the characteristic images in each of the eyes. The angle of all examined eyes was significantly widened with indentation (P < 0.01). The angle changes in eyes with RPB were significantly greater than in eyes with PAS or PIC (P < 0.01).

CONCLUSION

Indentation UBM gonioscopy is a very useful method for observing the angle and diagnosis of RPB, PAS, and PIC.

Relationship between the Extent of Peripheral Anterior Synechiae and the Severity of Visual Field Defects in Primary Angle-closure Glaucoma

We investigated the relationship between the circumferential extent of peripheral anterior synechiae (PAS) and the severity of visual field defects in primary angle-closure glaucoma (PACG). Correlations between visual field defects and the extent of PAS were analyzed in 73 eyes; 28 with and 45 without acute attacks. Spearman's correlation coefficient between the severity of visual field defects and the extent of PAS was 0.348 (P = 0.003) in all subjects (n = 73), 0.377 (P = 0.012) in the PACG eyes without acute attacks (n = 45), and 0.338 (P = 0.079) in the eyes with acute attacks (n = 28). Our results showed a statistically significant correlation between the extent of PAS and the severity of visual field damage in PACG overall, and especially in PACG patients without a history of acute attacks.

Long-term success of argon laser peripheral iridoplasty in the management of plateau iris syndrome

OBJECTIVE

To document the long-term effect of argon laser peripheral iridoplasty (ALPI) in eyes with plateau iris syndrome.

DESIGN

Retrospective, noncomparative, interventional case series.

SETTING

New York Eye and Ear Infirmary.

METHODS

The charts of all patients with plateau iris syndrome treated with ALPI from 1982 to 1991 and subsequently followed for 6 or more years were retrospectively reviewed. Patients with lens-related mechanisms contributing to angle closure (e.g., phacomorphic or malignant glaucoma) were excluded.

MAIN OUTCOME MEASURES

Necessity for repeat ALPI and/or any additional means of intervention.

RESULTS

A total of 26 ALPI procedures were performed in 23 eyes of 14 patients (4 men, 10 women). The mean age was 61+/-8.7 years. The mean follow-up was 78.9+/-8.0 months (range, 72-188 months). The angle in 20 of 23 (87.0%) eyes remained open throughout the entire follow-up period after only 1 treatment with ALPI. In 3 eyes, there was gradual reclosure of the angle 5 to 9 years after initial ALPI, but they were readily reopened and maintained open by a single repeat treatment. No filtration surgery was necessary in any eye during follow-up.

CONCLUSIONS

ALPI is highly effective in eliminating residual appositional closure after laser iridotomy caused by plateau iris syndrome. The effect is maintained for years, although a small proportion of patients might require retreatment.

Synechial angle closure pattern in Chinese chronic primary angle-closure glaucoma patients

PURPOSE

The aim of this retrospective clinical study is to investigate the pattern of synechial angle closure in a group of Hong Kong Chinese with chronic primary angle-closure glaucoma.

METHODS

The anterior angle of the upper, lower, medial, and lateral quadrants of 84 eyes from Hong Kong Chinese patients with chronic primary angle-closure glaucoma were assessed by the same examiner using indentation gonioscopy.

RESULTS

The incidences of synechial angle closure at the superior, nasal, inferior, and temporal quadrants were 98% (83/84), 77% (65/84), 31% (26/84), and 94% (79/84), respectively. The Fisher exact test showed that the incidence of synechial angle closure at the superior quadrant was significantly higher than the nasal (P = 0.005) and inferior (P < 0.001) quadrants, but not the temporal quadrant (P = 0.07).

CONCLUSION

Synechial angle closure is circumferential with asymmetry in these Chinese patients with chronic primary angle-closure glaucoma. The superior and temporal quadrants of the anterior angle may be the earliest sites of the synechial angle closure. The anterior angle may close synechially at the superior and temporal quadrants with gradual extension on the nasal quadrant, until the angle may close at the inferior quadrant.

A proposed simple method for measurement in the anterior chamber angle: biometric gonioscopy

OBJECTIVE

To design a system of gonioscopy that will allow greater interobserver reliability and more clearly defined screening cutoffs for angle closure than current systems while being simple to teach and technologically appropriate for use in rural Asia, where the prevalence of angle-closure glaucoma is highest.

DESIGN

Clinic-based validation and interobserver reliability trial.

PARTICIPANTS

Study 1: 21 patients 18 years of age and older recruited from a university-based specialty glaucoma clinic; study 2: 32 patients 18 years of age and older recruited from the same clinic.

INTERVENTION

In study 1, all participants underwent conventional gonioscopy by an experienced observer (GLS) using the Spaeth system and in the same eye also underwent Scheimpflug photography, ultrasonographic measurement of anterior chamber depth and axial length, automatic refraction, and biometric gonioscopy with measurement of the distance from iris insertion to Schwalbe's line using a reticule based in the slit-lamp ocular. In study 2, all participants underwent both conventional gonioscopy and biometric gonioscopy by an experienced gonioscopist (NGC) and a medical student with no previous training in gonioscopy (JK).

MAIN OUTCOME MEASURES

Study 1: The association between biometric gonioscopy and conventional gonioscopy, Scheimpflug photography, and other factors known to correlate with the configuration of the angle. Study 2: Interobserver agreement using biometric gonioscopy compared to that obtained with conventional gonioscopy.

RESULTS

In study 1, there was an independent, monotonic, statistically significant relationship between biometric gonioscopy and both Spaeth angle (P = 0.001, t test) and Spaeth insertion (P = 0.008, t test) grades. Biometric gonioscopy correctly identified six of six patients with occludable angles according to Spaeth criteria. Biometric gonioscopic grade was also significantly associated with the anterior chamber angle as measured by Scheimpflug photography (P = 0.005, t test). In study 2, the intraclass correlation coefficient between graders for biometric gonioscopy (0.97) was higher than for Spaeth angle grade (0.72) or Spaeth insertion grade (0.84).

CONCLUSION

Biometric gonioscopy correlates well with other measures of the anterior chamber angle, shows a higher degree of interobserver reliability than conventional gonioscopy, and can readily be learned by an inexperienced observer.

Clarifying the nomenclature for primary angle-closure glaucoma

Despite tremendous development in the field of glaucoma, there is confusion in the nomenclature system for classification, gonioscopy, and mechanisms of primary angle-closure glaucoma. In this article, we critically review the various nomenclature systems and suggest some modifications to the current classifications. These include four diagnostic categories: 1) angle-closure glaucoma suspect; 2) angle-closure hypertension; 3) chronic angle-closure glaucoma; and 4) acute angle-closure glaucoma. Gonioscopy is valuable for evaluating primary angle-closure glaucoma but more precise descriptions of gonioscopic observations are needed. Because of racial differences in the prevalence and mechanisms of primary angle-closure glaucoma, worldwide population-based study is necessary. Newer technologies, such as ultrasound biomicroscopy, show promise for the study of primary angle-closure glaucoma.

Incidence of acute angle-closure glaucoma after pharmacologic mydriasis

PURPOSE

To study the incidence of acute angle-closure glaucoma secondary to pupillary dilation and to identify screening methods for detecting angles at risk of occlusion.

METHODS

We studied 5,308 respondents to the Baltimore Eye Survey, a cross-sectional, population-based survey conducted in a multiracial urban community. We measured incidence of acute angle-closure glaucoma after pharmacologic mydriasis and the specificity and sensitivity associated with three screening criteria in identifying those with potentially occludable angles. The screening factors were presence of shallow anterior chamber on penlight examination, history of glaucoma, and blindness.

RESULTS

Of the 4,870 subjects whose eyes were dilated on screening examination, none developed acute angle-closure glaucoma. However, 38 patients of the 1,770 who were referred for definitive eye examination were judged to have occludable angles on the basis of gonioscopic methods. Of note, subjects aged 70 years and more were three times more likely to have occludable angles than those aged 40 to 69 years (P < .004) In 14 black subjects with occludable angles, six were detected by history of glaucoma and not by shallow anterior chamber configuration; alternatively, in 24 white subjects, 11 (46%) were detected on the basis of shallow anterior chambers (Fisher's exact test, P = .014). When the three screening factors were considered alone and in combination, the most effective combination for predicting a potentially occludable angle was to use shallow anterior chamber on penlight examination and history of glaucoma. These criteria provide 60.5% sensitivity and 93.3% specificity.

CONCLUSION

If screening is performed accurately and the results are negative, the risk of dilating a potentially occludable angle was less than one in 333 subjects (negative predictive value, 0.997) in this population.

Management of the hypotonous cyclodialysis cleft

Authoritative experience in the management of hypotonous cyclodialysis clefts is difficult to obtain because of their rarity. In this study, the authors describe nine patients with hypotonous cyclodialyses clefts: six patients were treated successfully with argon laser photocoagulation to the cleft surfaces; in one patient, cleft diathermy was used to seal an incompletely closed cleft after a single argon laser treatment; one patient responded to conservative management; another patient did not require treatment. Four cases followed ocular trauma and five occurred after extracapsular cataract extraction and posterior chamber intraocular lens implantation. In three patients, the anterior chamber was too shallow to permit gonioscopy; sodium hyaluronate (Healon) was used to reform the anterior chamber, to delineate the extent of the cyclodialysis cleft, and to provide maximal access for the argon laser treatment. In another patient, laser cleft consolidation was successful only after fully opening the cleft with sodium hyaluronate. The evolution of the laser photocoagulation technique used by the authors is described. Laser cyclodialysis cleft consolidation can be repeated easily and safely. The authors recommend argon laser photocoagulation as the primary management approach. Intracameral viscoelastic agents are useful adjuncts. The complications of cleft lasering are minor, although a hypertensive episode commonly occurs in the early postoperative period as the cleft closes. Major intraocular surgeries usually can be avoided.

Surgical goniosynechialysis for angle-closure glaucoma

Fifteen patients with synechial angle-closure glaucoma uncontrolled by medical and laser therapy were treated with surgical goniosynechialysis. Five patients were treated with goniosynechialysis alone, and ten were treated with goniosynechialysis in combination with other surgical procedures. The procedure was successful, in terms of reducing synechiae, in 14 eyes (93%). The extent of angle closure was reduced from 340 degrees +/- 45 degrees (mean +/- standard deviation) preoperatively to 80 degrees +/- 70 degrees postoperatively; the mean reduction was 260 degrees +/- 95 degrees (P less than 0.0001) for the group overall and 280 degrees +/- 80 degrees (P less than 0.0007) for the subgroup treated with goniosynechialysis alone. The mean preoperative intraocular pressure (IOP) was 40 +/- 4 mmHg. The mean postoperative IOP was 14 +/- 4 mmHg. The mean reduction in IOP was 26 +/- 15 mmHg (P less than 0.0001) for the group overall and 27 +/- 18 mmHg (P less than 0.015) for the subgroup treated with goniosynechialysis alone. Glaucoma medications were reduced from a mean of 2.6 +/- 1.0 preoperatively to 1.1 +/- 1.2 postoperatively for the group overall and to 1.4 +/- 1.5 for the subgroup treated with goniosynechialysis alone. Complications consisted of two eyes with intraoperative bleeding. One of these required intraoperative conversion to surgical trabeculectomy. The other was associated with a transient postoperative IOP elevation to 40 mmHg. Surgical goniosynechialysis may be an effective means of reducing synechiae and lowering IOP, either alone or in conjunction with other surgical procedures, in patients with angle closures of less than 6 months' duration.

Diagnosing acute angle-closure glaucoma: a flowchart

Acute angle-closure glaucoma is an ophthalmological emergency. Not all eyes will be responsive to an arbitrary medical regimen. Successful therapy is based upon understanding the mechanism of the angle-closure. A step-by-step flow chart for diagnosis of acute angle-closure glaucoma is presented with explanation of various signs and descriptions of appropriate diagnostic tests.

Anterior chamber angle in the exfoliation syndrome

The gonioscopic findings of 76 patients with the exfoliation syndrome were reviewed. A high frequency of narrowness of the anterior chamber (AC) angle was found (32%). 18% had angles considered occludable, and 14% had obvious angle-closure glaucoma as shown by the presence of peripheral anterior synechias (PAS). Increased pigmentation of the posterior trabecular meshwork (PTM) was noted in all cases. When this pigmentation was markedly asymmetrical, unilateral exfoliation with glaucoma was common in the more pigmented eye. In addition heavy angle pigmentation in the absence of exfoliation was noted in the fellow eye of patients with characteristic exfoliated material in the other eye. Increased pigmentation of the PTM may be the earliest detectable sign of the exfoliation syndrome (ES). The clinical significance of our estimating PTM pigmentation at the 12 o'clock position is discussed. In view of the accelerated optic nerve damage associated with the development of glaucoma secondary to ES, routine estimation of the pigmentation of the PTM at 12 o'clock is recommended in the hope of early detection of cases of otherwise inapparent ES.

Treatment of a cyclodialysis cleft with argon laser photocoagulation in a patient with a shallow anterior chamber

A 27-year-old man developed a traumatic cyclodialysis cleft with resulting hypotony. He had a flat peripheral anterior chamber, but the chamber was successfully deepened with the help of a Zeiss four-mirror goniolens, and the cyclodialysis cleft treated with argon laser photocoagulation.

Modern goniosynechialysis for the treatment of synechial angle-closure glaucoma

A new and successful technique for goniosynechialysis is described. The essentials of the technique include: (1) use of the chamber deepening procedure to provide a wide, safe entrance to the angle; (2) use of sodium hyaluronate to hold the deepened configuration and to stop and localize bleeding, thus maintaining visibility; (3) use of an irrigating cyclodialysis spatula to hold the deepened chamber, to stop bleeding and to perform the lysis; and (4) direct visualization of the angle. Four cases with severe synechial angle closure of one year's duration or less were cured. An additional case of longer duration was significantly improved. The procedure should be considered for those patients who have developed significant synechial angle closure and high pressure, and in whom the synechiae have not been present for a prolonged period of time.

Argon laser iris photocoagulation to relieve acute angle-closure glaucoma

Two patients, a 67-year-old woman and a 24-year-old man, suffered acute attacks of angle-closure glaucoma. After standard treatment methods had failed, argon laser iris photocoagulation was used to relieve the attacks. In one case the argon laser photocoagulation relieved the pupillary block, decreasing the intraocular pressure and permitting successful argon laser peripheral iridotomy. In the second case, argon laser photocoagulation broke up the posterior synechiae, decreasing the intraocular pressure.