Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration

The Japan Glaucoma Society guidelines for glaucoma 5th edition

We are pleased to bring you the 5th edition of the Glaucoma Clinical Practice Guidelines. Clinical practice guidelines are based on evidence (scientific grounds). It is a document that presents the treatment that is the most appropriate for the patient. "Glaucoma Clinical Guidelines" was first published in 2003. This was the first guideline for glaucoma treatment in Japan. The principle of glaucoma treatment is to lower intraocular pressure. Means for lowering intraocular pressure includes drugs, lasers, and surgery; Glaucoma is a disease that should be considered as a complex syndrome rather than a single condition. Therefore, the actual medical treatment is not as simple as one word. This time we set the Clinical Questionnaire with a focus on glaucoma treatment. We hope that you will take advantage of the 5th edition.

Clinical implication of recent randomized control trial in primary angle-closure disease management

Blindness due to primary angle-closure glaucoma (PACG) can be reduced significantly if the ongoing angle-closure process is arrested at an early stage. Various treatments such as laser peripheral iridotomy (LPI), iridoplasty, and clear lens extraction (CLE) have been advocated as first-line therapy for primary angle-closure (PAC), PACG, and high-risk cases of primary angle-closure suspect (PACS). EAGLE study, propagated the effectiveness of CLE over LPI for the management of primary angle closure and have sparked controversy regarding the role of LPI as a first line procedure. Randomized controlled trials (RCT), systematic reviews, and meta-analyses of RCTs done on the same question provide us with a solid base for creating guidelines/modules for our day-to-day clinical practice. A systematic review was conducted, searching several databases, including PubMed, Cochrane Library, EMBASE, and ClinicalTrials.gov, for the last 16 years (January 2005–December 2021) for RCTs with data published related to primary angle-closure disease (PACD). The search strategy included the following terms: “Primary Angle Closure disease,” “Primary Angle Closure Glaucoma,” “Primary Angle Closure,” “Primary Angle Closure Suspect,” “clear lens extraction,” “laser iridotomy,” “laser peripheral iridotomy,” “argon laser peripheral iridoplasty,” “selective laser trabeculoplasty,” “trabeculectomy,” “randomized control trial,” and “meta-analysis of randomized control trial.” In this review, we will discuss recently published RCTs (within the last 16 years) for the management of PACD and their clinical implications in day-to-day practice.

Imaging of the Ciliary Body: A Major Review

PURPOSE

We conducted a systematic search of literature to understand the various methods of imaging of the ciliary body.

METHODS

PubMed, Science Direct, Cochrane Library and Google Scholar were searched comprehensively and systematically to find studies related to the various modalities of ciliary body imaging.

RESULTS

The various ciliary body parameters that have been described are Ciliary body thickness, Ciliary body length, ciliary muscle thickness, ciliary process length, ciliary muscle length, ciliary muscle anterior length, trabecular ciliary process distance and Iris ciliary process distance. The various angles which have been measured, which mostly have a significance in Primary angle closure glaucoma (PACG) are Iris ciliary angle, Trabecular ciliary angle, scleral ciliary process angle. Various authors have defined them in various ways with subtle differences. Plateau iris and PACG mechanisms, not forgetting malignant glaucoma are better understood with imaging of the ciliary body using the ultrasound biomicroscopy (UBM). The anterior segment optical coherence tomography (ASOCT) imaging of the ciliary body has been described albeit with its own disadvantages. A few other fields dependant on the importance of ciliary body imaging are intravitreal injections, pars plana vitrectomy, measurements for implantable collamer lens (ICL) and of utmost importance, the differentiating features of ciliary body masses.

CONCLUSION

The UBM is still preferred over the ASOCT for imaging of the ciliary body. A lot of lacunae of knowledge still exists and consensus has to be reached on defining all the parameters universally. Future studies will be able to shed more light on the role of the ciliary body in the many ocular disorders mentioned in this review.

Recommendations for ultrasound examination in ophthalmology. Part I: Ultrabiomicroscopic examination

Range of ultrasounds used in medical imaging is between 2 and 80 MHz. The highest frequencies are applied in medical imaging of an anterior segment of an eyeball. This paper covers the newest method of ultrasound imaging - an ultrabiomicroscopic examination. Its name reflects resolution which has so far been unavailable, and which allows for imaging a structure of the examined tissues. The article includes basic information about the structure and principles of operation of ultrabiomicroscopic examination tools. Moreover, its position among other methods for echographic examination of an eyeball was determined. Examination techniques and the role of standards of conduct at each stage of a diagnostic procedure were discussed. A role of insufficient cooperation between constructors of new ultrasonographic diagnostic tools and software IT specialist with the users of these tools, which results in the lack of consistency between the components of these sets was emphasized. Based on long term experience in ultrabiomicroscopic examinations, the authors shared observations on practical aspects of this method. Finally, indications and contraindications for ultrabiomicroscopic diagnostics were listed. Introduction of an ultrahigh frequency ultrasound probe allowed for the visualization of an post-iridial area of an anterior segment of an eyeball - an area whose diagnosis is impossible with other diagnostic methods. A wide spectrum of diagnostic indications, which covers both diseases and development anomalies of an anterior segment of an eyeball, confirms a special meaning of this method.

Range of ultrasounds used in medical imaging is between 2 and 80 MHz. The highest frequencies are applied in medical imaging of an anterior segment of an eyeball. This paper covers the newest method of ultrasound imaging – an ultrabiomicroscopic examination. Its name reflects resolution which has so far been unavailable, and which allows for imaging a structure of the examined tissues. The article includes basic information about the structure and principles of operation of ultrabiomicroscopic examination tools. Moreover, its position among other methods for echographic examination of an eyeball was determined. Examination techniques and the role of standards of conduct at each stage of a diagnostic procedure were discussed. A role of insufficient cooperation between constructors of new ultrasonographic diagnostic tools and software IT specialist with the users of these tools, which results in the lack of consistency between the components of these sets was emphasized. Based on long term experience in ultrabiomicroscopic examinations, the authors shared observations on practical aspects of this method. Finally, indications and contraindications for ultrabiomicroscopic diagnostics were listed. Introduction of an ultrahigh frequency ultrasound probe allowed for the visualization of an post-iridial area of an anterior segment of an eyeball – an area whose diagnosis is impossible with other diagnostic methods. A wide spectrum of diagnostic indications, which covers both diseases and development anomalies of an anterior segment of an eyeball, confirms a special meaning of this method.

The effect of internal fixation lamp on anterior chamber angle width measured by anterior segment optical coherence tomography

PURPOSE

To study the effect of the internal fixation lamp on anterior chamber width measured by anterior segment optical coherence tomography.

METHODS

In a prospective cross sectional observational study, consecutive 22 right eyes of 22 patients (4 men and 18 women) with suspected primary angle closure underwent swept source domain anterior segment optical coherence tomography (AS-OCT), (CASIA SS-1000, Tomey, Nagoya, Japan). Anterior chamber parameters of angle opening distance (AOD), trabecular-iris angle (TIA), angle recess area (ARA) at 500 or 750 µm from scleral spur and pupil diameter were measured by AS-OCT in a three-dimensional mode in 4 quadrants (superior, inferior, temporal and nasal) in dark room setting both with and without internal fixation lamp.

RESULTS

Anterior segment parameters of AOD 500 in superior, inferior and temporal quadrants, AOD 750 at superior and nasal, TIA 500 at superior, and inferior and TIA 750 at superior and nasal, and ARA 500 or 750 at superior and inferior with internal fixation lamp were greater and the pupil diameter was significantly (all P < 0.05, paired t test) smaller than when measured without fixation lamp.

CONCLUSIONS

Internal fixation lamp of the anterior segment OCT makes the pupil constrict and angle wider. When using AS-OCT with usual setting with internal fixation lamp on with eyes in which the anterior chamber angle is narrow but open, it is recommended that the internal fixation lamp be turned off to ensure a clear indication as to whether the angle is open or closed in the dark.

Comparison of Anterior Chamber Parameters in Patients With Plateau Iris Configuration and Pupillary Block Using ASOCT

PURPOSE

To quantitatively analyze the anterior chamber parameters in patients with pupillary block (PB) and plateau iris configuration (PIC) using anterior segment optical coherence tomography (ASOCT).

PATIENTS AND METHODS

In this cross-sectional study, nonglaucomatous subjects consecutively recruited and a total of 212 eyes divided into 3 groups of PIC (31 eyes), PB (60 eyes), and open angles (121 eyes) based on gonioscopic and ultrasound biomicroscopy findings. All patients underwent ASOCT imaging and A-scan biometry of both eyes. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness (IT), iris curvature, lens vault (LV), anterior vault, and angle parameters including angle opening distance, and trabecular iris space area were measured in qualified images using the Zhongshan Angle Assessment Program, and compared using linear mixed model. The data from 1 eye of each subject were used for final analysis.

RESULTS

Mean age was 64.5±12.1, 64.8±10.5, and 62.3±9.2 years for PB, PIC, and open angle eyes, respectively (P=0.26). There was no significant difference in angle parameters (angle opening distance and trabecular iris space area at 250, 500, and 750 µm from sclera spur), anterior segment parameters (ACD and ACA), iris area, iris curvature, and LV between PB and PIC groups. PIC eyes had greater IT at 750 µm from sclera spur than the PB group (P=0.05). Normal eyes had greater ACD, ACA, and anterior chamber width, and angle parameters and lesser LV and iris curvature than the other 2 groups.

CONCLUSIONS

ASOCT parameters are not significantly different between PB and PIC eyes. PIC eyes may have greater IT at its base.

Recurrent acute angle-closure attack due to plateau iris syndrome after cataract extraction with or without argon laser peripheral iridoplasty: a case report

Background

We describe two cases of recurrent acute angle-closure attack in patients with plateau iris syndrome after cataract extraction. Argon laser peripheral iridoplasty and cataract extraction have been used to reduce the occurrence of acute angle-closure attack in plateau iris syndrome although the risk cannot be completely eliminated. There is no consensus on the long term management of plateau iris syndrome. This is, as far as we know, the first case report of recurrent acute angle-closure attack in plateau iris syndrome after cataract extraction.

Case presentation

We report two cases of recurrent acute angle-closure attack in 2 Chinese patients with plateau iris syndrome. The first patient was a 69 year-old woman who received bilateral argon laser peripheral iridoplasty and cataract extraction 2 years prior to the latest acute angle-closure with right eye intraocular pressure 48 mmHg. The attack was aborted medically. Peripheral iridotomy was patent and argon laser peripheral iridoplasty marks were mostly at peripheral 2/3 of the iris. Anterior segment optical coherence tomography confirmed bilateral plateau iris configuration. Use of long term pilocarpine or repeated argon laser peripheral iridoplasty to prevent recurrent angle-closure attack was discussed but she opted for observation. The second patient was a 64 year-old man presented with acute angle-closure after cataract extraction despite placement of laser peripheral iridotomy. Plateau iris syndrome was confirmed by anterior segment optical coherence tomography and he received argon laser peripheral iridoplasty.

Conclusions

Acute angle-closure due to plateau iris syndrome can still occur despite previous cataract extraction and argon laser peripheral iridoplasty. These are the first reported cases of recurrent acute angle-closure attack due to plateau iris syndrome following cataract extraction, with or without previous argon laser peripheral iridoplasty. Repeated treatment with argon laser peripheral iridoplasty or pilocarpine could be considered although the long term efficacy is questionable. Argon laser peripheral iridoplasty should be applied as peripheral as possible so as to open up the drainage angle effectively.

Anterior and posterior ocular biometry in healthy Chinese subjects: data based on AS-OCT and SS-OCT

Background

To measure the anterior and posterior ocular biometric characteristics concurrently and to determine the relationship between the iris and choroid in healthy Chinese subjects.

Methods

A total of 148 subjects (270 eyes) were enrolled in this cross-section study. The anterior and posterior ocular biometric characteristics were measured simultaneously by anterior segment optical coherence tomography (AS-OCT) and swept-source optical coherence tomography (SS-OCT).

Results

Compared with male eyes, female eyes had narrower anterior biometric parameters that presented with smaller anterior segment parameters [including anterior chamber depth (ACD), width (ACW), area (ACA), and volume (ACV); (all p<0.001)], narrower anterior chamber angle parameters [including angle opening distance (AOD750), trabecular–iris space area (TISA750), and angle recess area (ARA); (all p<0.001)], higher iris curvature (ICURV) (p = 0.003), and larger lens vaults (LV) (p = 0.019). These anterior ocular biometric parameters were correlated with increasing age (p<0.01). Iris thickness (IT750) and iris area (IAREA) were associated with age, ACW, and pupil diameter (all p<0.05), while choroidal thickness (CT) was associated with age, gender, and axial length (all p<0.05). Univariate regression analysis showed that greater CT was significantly associated with smaller IAREA (p = 0.026).

Conclusion

Compared with male eyes, female eyes had narrower anterior biometric parameters that correlated with increasing age, which would be helpful in explaining the higher prevalence of angle closure rates in the female gender and in aging people. Increased CT might be associated with smaller iris area; however, this possibility needs to be investigated in future studies before this conclusion is made.

Enhancing the early differential diagnosis of plateau iris and pupillary block using a-scan ultrasonography

Purpose

To distinguish the frequently misdiagnosed plateau iris eyes from pupillary block group and normal group, we compared the ocular biometrical parameters of them by A-scan ultrasongraphy.

Methods

In total, we retrospectively reviewed general characteristics and ocular findings including ocular biometric measurements of 71 normal, 39 plateau iris, and 83 pupillary block eyes.

Results

The normal controls, plateau iris group and pupillary block group were significantly different in age, but not in gender. The anterior chamber depth tended to decrease and the lens thickness tended to increase from normal to plateau iris to pupillary block eyes. Compared to those of plateau iris group, the pupillary block group had significantly shallower anterior chamber depth (2.90mm vs. 2.33mm; p<0.001), thicker lens (4.77mm vs. 5.11mm; p<0.001), shorter axial length (23.16mm vs. 22.63mm; p<0.001), smaller relative lens position (2.28 vs. 2.16; p<0.001) and larger lens/axial length factor (2.06 vs. 2.26; p<0.001). However, when comparing plateau iris and normal eyes, only axial length and lens/axial length factor were significantly different (23.16 vs. 23.54; p<0.05 and 2.06 vs. 1.96; p<0.05).

Conclusions

Measured by A-scan ultrasonography, the ocular biometrics of plateau iris were significantly different from those of pupillary block eyes. However, our A-scan ultrasongraphy generally found no significant biometric differences between plateau iris and normal eyes. These findings suggest that while A-scan ultrasonography might be used as a practical tool for differentiating plateau iris and papillary block eyes, a more meticulous gonioscopy and other assessments may be necessary to distinguish plateau iris from normal eyes.

Association between baseline iris thickness and prophylactic laser peripheral iridotomy outcomes in primary angle-closure suspects

OBJECTIVE

To evaluate the association between baseline measurements of iris thickness at 3 positions and change in anterior segment biometric parameters after prophylactic laser peripheral iridotomy (LPI).

DESIGN

Prospective clinical cohort study.

PARTICIPANTS

Fifty-two eyes of 52 nonglaucomatous subjects with anatomically narrow angles.

METHODS

Anterior segment optical coherence tomography (ASOCT) images captured before and after LPI were analyzed using customized software, the Zhongshan Angle Assessment Program (ZAAP) (Zhongshan Ophthalmic Centre, Guangzhou, China). Differences in preoperative and postoperative measurements for anterior segment biometric parameters were compared by paired Student t tests. Multivariate linear regression models, adjusted for age, sex, ethnicity, and preoperative pupil diameter, were used to examine the association between the baseline measurements of iris thickness at 3 positions and the change in anterior segment biometric parameters after LPI.

MAIN OUTCOME MEASURES

Baseline iris thickness measured at 750 μm from the scleral spur (IT750), iris thickness measured at 2000 μm from the scleral spur (IT2000), and maximal iris thickness (ITM). Changes in iris curvature (ICURV) and trabecular-iris space area at 500 μm from the scleral spur (TISA500) and 750 μm from the scleral spur (TISA750) after LPI.

RESULTS

The ICURV significantly decreased, whereas TISA500 and TISA750 significantly increased after LPI (all P < 0.0001). Lower baseline IT750 was significantly associated with greater postoperative increases in TISA500 and TISA750 (both P < 0.05). Lower baseline IT2000 and ITM were significantly associated with greater postoperative decrease in ICURV (both P < 0.05).

CONCLUSIONS

Our results showed that lower baseline measurements of iris thickness are associated with greater decrease in ICURV and increases in TISA500 and TISA750 after LPI. This suggests that eyes with thinner irides undergoing LPI were more likely to exhibit greater magnitude of change in terms of flattening of the iris convexity (i.e., ICURV) and widening of the anterior chamber angle (i.e., TISA500 and TISA750).

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.

Light-dark changes in iris thickness and anterior chamber angle width in eyes with occludable angles

BACKGROUND

The purpose of this study was to investigate and measure light-dark changes in iris thickness (IT) and anterior chamber angle width in eyes with occludable angles and open angles by using anterior segment optical coherence tomography (AS-OCT).

METHODS

We examined 153 eyes of 153 Japanese patients with primary angle closure suspect, primary angle closure, primary angle closure glaucoma, or primary open angle glaucoma. AS-OCT was used to determine pupil diameter, IT, angle opening distance at 500 μm (AOD₅₀₀), and trabecular-iris space area at 500 μm (TISA₅₀₀) in each quadrant of the anterior chamber angle (superior, inferior, temporal, and nasal) under light and dark conditions.

RESULTS

In the angle closure cases, IT, AOD₅₀₀ and TISA₅₀₀ in the dark varied significantly among the four quadrants (P < 0.05, analysis of variance). In contrast, in the open angle cases, IT, AOD₅₀₀ and TISA₅₀₀ in the dark did not differ significantly among the four quadrants. In the angle closure cases and the open angle cases, significant negative associations were found between IT difference [IT(light)-IT(dark)] and AOD₅₀₀ difference [AOD₅₀₀(light)-AOD₅₀₀(dark)] (R = -0.411, P < 0.001 and R = -0.501, P = 0.001, respectively) and between IT difference and TISA₅₀₀ difference [TISA₅₀₀(light)-TISA₅₀₀(dark)] (R = -0.475, P < 0.001 and R = -0.462, P = 0.002, respectively).

CONCLUSION

Our results suggest that thickening of the iris root under dark conditions is related to the mechanism of primary angle closure. It is important to analyze both the angle structure and peripheral IT in each quadrant.

Glaucoma

Most medical practitioners have regular contact with adults who have one of the two forms of glaucoma: open-angle glaucoma or angle-closure glaucoma. Data from population-based surveys indicate that one in 40 adults older than 40 years has glaucoma with loss of visual function, which equates to 60 million people worldwide being affected and 8·4 million being bilaterally blind. Even in developed countries, half of glaucoma cases are undiagnosed. Glaucoma is mostly asymptomatic until late in the disease when visual problems arise. Vision loss from glaucoma cannot be recovered, and improved case-detection methods for glaucoma are needed. Glaucoma is commonly treated with daily eye-drop drugs, but adherence to treatment is often unsatisfactory. As a usually asymptomatic and chronic disease, glaucoma has similar treatment challenges to chronic systemic diseases. Similarities to the pathogenesis of common CNS diseases mean that common neuroprotective strategies might exist. Successful gene therapy, which has been used for other eye diseases might be possible for the treatment of glaucoma in the future.

Changes in anterior chamber configuration after cataract surgery as measured by anterior segment optical coherence tomography

PURPOSE

To evaluate the changes in anterior chamber depth (ACD) and angle width induced by phacoemulsification and intraocular lens (IOL) implantation in normal eyes using anterior segment optical coherence tomography (AS-OCT).

METHODS

Forty-five eyes (45 patients) underwent AS-OCT imaging to evaluate anterior chamber configuration before and 2 days after phacoemulsification and IOL implantation. We analyzed the central ACD and angle width using different methods: anterior chamber angle (ACA), trabecular-iris angle (TIA), angle opening distance (AOD), and trabecular iris surface area (TISA) in the nasal and temporal quadrants. Comparison between preoperative and postoperative measurement was done using paired t-tests and each of the angle parameters was analyzed with Pearson correlation testing. Subgroup analyses according to the IOL and axial length were performed with a general multivariate linear model adjusted for age.

RESULTS

Before surgery, the mean anterior chamber angle widths were 23.21 ± 6.70° in the nasal quadrant and 24.89 ± 7.66° in the temporal quadrant. The mean central ACD was 2.75 ± 0.43 mm. After phacoemulsification and IOL implantation, the anterior chamber angle width increased significantly to 35.16 ± 4.65° in the nasal quadrant (p = 0.001) and 36.03 ± 4.86° in the temporal quadrant (p = 0.001). Also, central ACD increased to 4.14 ± 0.31 mm (p = 0.001). AOD, TISA, and TIA increased significantly after cataract surgery and showed positive correlation with ACA.

CONCLUSIONS

After cataract surgery, the ACD and angle width significantly increased in eyes with cataract. AS-OCT is a good method for obtaining quantitative data regarding anterior chamber configuration.

Argon laser peripheral iridoplasty for plateau iris associated with iridociliary cysts: a case report

Introduction

Plateau iris is recognised as an important cause of primary angle closure glaucoma. The management of this condition generally comprises laser peripheral iridotomy and iridoplasty, to remove any component of relative pupillary block and to widen the iridotrabecular drainage angle respectively. However, plateau iris may be associated with multiple iris cysts at the iridociliary junction, which then presents diagnostic and management problems.

Case presentation

We present a fifty-three year old Caucasian gentleman with plateau iris associated with peripheral iris cysts, in which the iridotrabecular angle did not widen despite having had both laser peripheral iridotomy and iridoplasty. The patient has remained asymptomatic over 12 months, and is under close follow-up to monitor for signs of glaucoma.

Conclusion

Plateau iris with iridociliary cysts can be difficult to diagnose and manage. Ultrasound biomicroscopy should be performed on patients with appositional iridotrabecular angle closure on gonioscopy, especially if the angle closure is not relieved with either laser peripheral iridotomy or iridoplasty. Question marks can be raised as to the benefit of laser iridotomy when plateau iris without pupillary block has already been conclusively diagnosed on ultrasound biomicroscopy.

Atypical angle closures

PURPOSE OF REVIEW

Primary angle closure typically causes acute intraocular pressure rise in the phakic elderly. Alternative diagnoses, however, for which iridotomy is usually ineffective, occur commonly in younger, nonhyperopic, and pseudophakic patients.

RECENT FINDINGS

High-resolution ultrasonography has advanced our understanding of these entities. Management of platueau iris, present in over half of angle closures with patent iridotomy, may depend on disease stage. Early postoperative pseudophakic patients with myopic shift and narrow angle should be treated with laser capsulotomy for capsular block. Bilateral angle closure is usually due to an offending systemic pharmacologic agent, which must be stopped to resolve the closure. Ciliary body swelling often produces angle closure by blocking the access of aqueous to the anterior chamber, sometimes paradoxically after hypotony. Annular choroidal effusions, difficult to detect without ultrasound, may mimic angle closure. Although cycloplegic and corticosteroid therapy may resolve some entities, pars plana vitrectomy and lensectomy may be necessary to resolve severe ciliary block. We also discuss unique variants of angle closure in patients with retinal disease.

SUMMARY

Atypical angle closures should always be considered. Careful examination techniques and new technology can detect the mechanisms involved and direct treatment.

Migraine and anisocoria

A 42-year-old woman presents with headache and anisocoria. Gonioscopy suggested narrow angles. Ultrasound biomicroscopy confirmed the diagnosis. The patient underwent bilateral peripheral iridotomies with resolution of her symptoms. The differential diagnosis of headache and anisocoria are reviewed. Plateau iris syndrome and subacute angle closure are discussed.

Long Ciliary Processes With no Ciliary Sulcus and Appositional Angle Closure Assessed by Ultrasound Biomicroscopy

PURPOSE

Nonpupil block mechanisms and appositional angle closure after laser iridotomy (LI) have been reported as common findings in Asians. We evaluated the presence of these findings in a cohort of Brazilian patients using ultrasound biomicroscopy (UBM).

METHODS

This observational case-control study included 22 open angle eyes and 31 eyes with occludable angles on gonioscopy (defined by 2 examiners). UBM radial scans through a typical ciliary process were obtained in both light and dark conditions, at 6 and 12-o'clock positions. Long ciliary processes with no ciliary sulcus were determined on the basis of a reference line drawn perpendicular to the iris plane passing through a point located 750 mum from scleral spur. Trabecular ciliary processes distance was measured on 6-o'clock UBM images.

RESULTS

After LI, 52% of occludable angle eyes had appositional angle closure in both 6 and 12-o'clock UBM images. We also observed this finding in 14% and 23% of the control eyes (in 6 and 12-o'clock UBM images, respectively). A long ciliary process with no ciliary sulcus was observed in 61% of occludable angle eyes, and also in 32% of control eyes (6-o'clock UBM images). Control eyes had longer trabecular ciliary processes distance than occludable angle eyes (P<0.001).

CONCLUSIONS

The UBM finding of long ciliary processes associated with the absence of ciliary sulcus is not necessarily related to an anterior positioning of the ciliary processes. Whether UBM appositional angle closure after LI is associated with further angle closure process and/or poor intra-ocular pressure control remains to be evaluated.

Ultrahigh frame rate retrospective ultrasound microimaging and blood flow visualization in mice in vivo

To overcome frame rate limitations in high-frequency ultrasound microimaging, new data acquisition techniques have been implemented for 2-D (B-scan) and color flow visualization. These techniques, referred to as retrospective B-scan imaging (RBI) and retrospective color flow imaging (RCFI) are based on the use of the electrocardiogram (ECG) to trigger signal acquisitions. B-scan and color flow images are reconstructed by retrospectively assembling the processed data on a line-by-line basis. Retrospective techniques are used to produce the first in vivo B-scan and color flow images of mouse carotid arteries at frame rates up to 10,000 fps. Retrospective B-scan images of mouse heart were also produced at frame rates of 1000 fps using a version of RBI implemented on a commercial imaging system (Vevo660, VisualSonics, Toronto, ON, Canada). This technology enables detailed in vivo biomechanical studies of dynamic tissues such as the myocardium of the mouse heart with high temporal resolution.

New Gonioscopy System Using Only Infrared Light

PURPOSE

To describe an infrared gonioscopy system designed to observe the anterior chamber angle under natural mydriasis in a completely darkened room.

METHODS

An infrared light filter was used to modify the light source of the slit-lamp microscope. A television monitor connected to a CCD monochrome camera was used to indirectly observe the angle.

RESULTS

Use of the infrared system enabled observation of the angle under natural mydriasis in a completely darkened room.

CONCLUSION

Infrared gonioscopy is a useful procedure for the observation of the angle under natural mydriasis.

Evaluation and management of plateau iris syndrome: case report and review

BACKGROUND

This article documents a case of plateau iris syndrome and provides a review of the current concepts regarding the pathogenesis, diagnosis, and management of this condition.

CASE REPORT

A patient who had patent peripheral iridotomies O.D. and O.S. to treat previous episodes of acute angle closure came to clinic with unilaterally elevated intraocular pressures, narrow anterior chamber angles, and a flat iris configuration. The patient was diagnosed with plateau iris syndrome.

CONCLUSIONS

The clinician must be aware of, and be able to distinguish, the clinical signs that are characteristic of plateau iris syndrome. An understanding of the mechanisms involved in the development of this type of primary angle closure may facilitate its appropriate diagnosis and management.

Angle closure: classification, concepts, and the role of ultrasound biomicroscopy in diagnosis and treatment

The angle closure glaucomas are a diverse group of disorders characterized by mechanical blockage of the trabecular meshwork by the peripheral iris leading to elevated intraocular pressure and glaucoma. Understanding the pathophysiologic mechanisms underlying these disorders is essential for both diagnosis and management. This review covers the anatomy, etiology, classification, and therapy of the various angle closure glaucomas and the role that ultrasound biomicroscopy has played in helping us understand these diseases.

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.

Clinical Case Note. Incomplete and complete plateau iris syndrome

Plateau iris syndrome is considered to be a rare entity and has been classified into two subtypes, the complete and the incomplete forms. Herein a case is reported of plateau iris syndrome that had a postmydriatic rise in intraocular pressure (IOP) in one eye (complete syndrome) and no increase in IOP in the other (incomplete syndrome). The pre- and post-mydriasis ultrasound biomicroscopic findings were documented. These findings suggest that incomplete plateau iris syndrome may be caused by a difference in the extent of closure of the angle circumferentially over the 360 degrees of the angle.

Interventions for angle-closure glaucoma

PURPOSE

To assess the interventions to treat acute angle closure (AAC) and primary angle closure (PAC) with or without glaucomatous optic neuropathy.

CLINICAL RELEVANCE

Primary angle closure is one of the leading causes of blindness in East Asia. At present, there are few clinical guidelines on the optimal treatment of AAC or PAC in the affected or contralateral eye.

METHODS

All randomized clinical trials, prospective controlled clinical trials, nonprospective controlled clinical trials, and retrospective case series with >50 cases that evaluated treatments for AAC or PAC were included. Studies published in the English language were identified from MEDLINE, PubMed, EMBASE, and the Cochrane Collaborations, as well as by a hand search of the reference lists of important articles.

RESULTS

Nine randomized clinical trials and 24 nonrandomized clinical trials and large case series were evaluated. Laser peripheral iridotomy (LPI) has been found to be as effective as surgical peripheral iridectomy in randomized clinical trials of the affected and contralateral eyes of AAC or PAC patients with or without evidence of glaucoma. In another randomized clinical trial, latanoprost was found to decrease intraocular pressure (IOP) more than timolol for PAC in patients for whom LPI alone failed.

CONCLUSIONS

This review suggests that LPI should be recommended for the treatment of affected and contralateral eyes of AAC patients. In patients with PAC and insufficient treatment with LPI, latanoprost eye drops may decrease IOP more than timolol. There is still insufficient evidence about other interventions for the treatment of AAC and PAC.

A case of angle closure glaucoma caused by plateau iris and adie's pupil

PURPOSE

To describe a case of plateau iris associated with bilateral Adie's pupil.

DESIGN

Interventional case report.

METHODS

A 54-year-old woman presented with pain in her right eye and headache. Intraocular pressure was 34 mm Hg in the right eye. Light reflex was defective bilaterally.

RESULTS

Ultrasound biomicroscopic imaging revealed normal anterior chamber depth and narrow angle. The ciliary processes were situated anteriorly. The eyes showed supersensitivity to 0.125% pilocarpine. The patient was diagnosed as having bilateral angle-closure glaucoma induced by Adie's pupil and plateau iris.

CONCLUSION

Mild pupillary dilation caused by Adie's pupil may have played a role in the development of angle closure in the plateau iris configuration of our patient.

A prospective ultrasound biomicroscopy evaluation of changes in anterior segment morphology after laser iridotomy in Asian eyes

PURPOSE

To prospectively quantify changes in anterior segment morphology after laser iridotomy using gonioscopy and ultrasound biomicroscopy (UBM).

DESIGN

Prospective comparative observational case series.

PARTICIPANTS

Fifty-five fellow eyes of patients presenting with acute primary angle closure (APAC).

METHODS

The fellow eyes of patients presenting with APAC were examined with UBM, A-scan ultrasonography, and optical pachymetry at presentation and 2 weeks after sequential argon/neodymium yttrium-aluminum-garnet laser peripheral iridotomy (LPI). UBM images were analyzed using UBM Pro 2000 software. Baseline measurements were made both under standard lighting conditions and in darkness to look for changes in anterior segment findings.

MAIN OUTCOME MEASURES

The degree of angle opening was measured using the angle-opening distance (AOD) at 250 and 500 microm from the scleral spur (AOD250 and AOD500, respectively) and angle recess area (ARA).

RESULTS

Fifty-five Asian patients were examined; AOD250, AOD500, and ARA all significantly increased after sequential laser iridotomy (P < 0.002). Gonioscopic grading of the angle opening significantly increased in all 4 quadrants (P < 0.001). The Van Herick grade of limbal anterior chamber depth increased (P < 0.001), whereas the number of eyes classified as occludable decreased (73%-33%, P < 0.001). Anterior chamber depth did not change significantly (2.41 mm +/- 0.28 mm vs. 2.42 mm +/- 0.30 mm, P = 0.43) as measured with optical pachymetry. Increased illumination increased the angle-opening measures, but induced a different alteration in peripheral iris morphology. Illumination-induced changes were greater after iridotomy than before laser treatment.

CONCLUSIONS

In Asian eyes at high risk of developing APAC, sequential LPI produced a significant widening of the anterior chamber angle without deepening the anterior chamber centrally. LPI produces changes in iris morphology that are different from those caused by an increase in illumination, indicating that different mechanisms account for angle opening under these 2 conditions.

An ultrasound biomicroscopic study of the anterior segment in Indian eyes with primary angle-closure glaucoma

PURPOSE

To evaluate the presence of plateau iris in eyes with primary angle-closure glaucoma (PACG) after laser peripheral iridotomy by gonioscopy and ultrasound biomicroscopy and to evaluate the pathogenesis of this condition by comparing the UBM parameters of these eyes with those in normal subjects.

PATIENTS AND METHODS

This prospective study was carried out in the Glaucoma clinic of a tertiary eye care center. A detailed clinical examination including applanation tonometry, indentation gonioscopy with a Sussman four-mirror gonioscope, and ultrasound biomicroscopic examination in one randomly selected eye of 55 patients (55 eyes) with PACG who had undergone laser peripheral iridotomy and 22 normal subjects (22 eyes).

RESULTS

Among the PACG eyes, 40% (22/55) had an open angle (angle opening distance > 130 microns) and 60% (33/55) eyes had a narrow angle (angle opening distance <or= 130 microns). A large anteriorly placed ciliary process with a narrow ciliary sulcus was found in 9 of the 22 eyes with open angle (40.9%), and 22 of the 33 eyes with narrow angles (66.66%). Trabecular ciliary process distance was significantly larger in the eyes with open angles compared with those with narrow angles ( = 0.001).

CONCLUSIONS

Plateau iris was common in the clinic population studied. Anteriorly directed ciliary processes were seen both in eyes with plateau iris as well as in eyes with PACG that had deep anterior chambers after iridotomy.

Ultrasound biomicroscopic study of ciliary body changes in the post-treatment phase of Vogt-Koyanagi-Harada disease

AIMS

To investigate the usefulness of ultrasound biomicroscopy for evaluating changes in the ciliary body in patients with Vogt-Koyanagi-Harada disease.

METHODS

Ultrasound biomicroscopy was used to evaluate 14 eyes of seven patients diagnosed with Vogt-Koyanagi-Harada disease. Cross sectional images of the ciliary body and thickness of the pars plana 3.0 mm posterior to the scleral spur were examined. Predicted thickness of the pars plana was obtained by multiple linear regression analysis of thickness in the acute phase and in the remission phase.

RESULTS

In the active phase, the cross sectional images showed a shallow anterior chamber in eight of the 14 eyes, ciliochoroidal detachment in five eyes, and a thickened ciliary body in all 14 eyes. Internal reflectivity of the ciliary stroma was low, with ciliary processes being unclear in 13 eyes. One month after steroid treatment, slit lamp examination findings were normal in 14 eyes. 10 eyes of five patients were examined by ultrasound biomicroscopy at this stage. Ciliochoroidal detachment was no longer seen in any eye. Internal reflection of the ciliary stroma became relatively homogeneous, and the ciliary processes were seen, though not clearly. However, the pars plana remained thickened. The actual thickness was greater at 1 month after steroid treatment than the predicted thickness for the remission phase. In the remission phase, the internal reflection was homogeneous and the ciliary processes were delineated clearly in all 14 eyes.

CONCLUSION

Objective, quantitative evaluation of the ciliary body is possible with ultrasound biomicroscopy during the course of Vogt-Koyanagi-Harada disease. Ultrasound biomicroscopy is useful in determining disease activity in the anterior segment and in monitoring the clinical course, and it may improve evaluation of the efficacy of treatment.