Primary Angle-Closure Disease Preferred Practice Pattern®

Secretary for Quality of Care Timothy W. Olsen, MD Academy Staff Ali Al-Rajhi, PhD, MPH Andre Ambrus, MLIS Meghan Daly Flora C. Lum, MD Medical Editor: Susan Garratt Approved by: Board of Trustees September 12, 2020 Copyright © 2020 American Academy of Ophthalmology® All rights reserved AMERICAN ACADEMY OF OPHTHALMOLOGY and PREFERRED PRACTICE PATTERN are registered trademarks of the American Academy of Ophthalmology. All other trademarks are the property of their respective owners. Preferred Practice Pattern® guidelines are developed by the Academy's H. Dunbar Hoskins Jr., MD Center for Quality Eye Care without any external financial support. Authors and reviewers of the guidelines are volunteers and do not receive any financial compensation for their contributions to the documents. The guidelines are externally reviewed by experts and stakeholders before publication. GLAUCOMA PREFERRED PRACTICE PATTERN® DEVELOPMENT PROCESS AND PARTICIPANTS The Glaucoma Preferred Practice Pattern® Panel members wrote the Primary Angle Closure Disease Preferred Practice Pattern® guidelines (PPP). The PPP Panel members discussed and reviewed successive drafts of the document, meeting in person twice and conducting other review by e-mail discussion, to develop a consensus over the final version of the document. Glaucoma Preferred Practice Pattern Panel 2019-2020 Steven J. Gedde, MD, Chair Philip P. Chen, MD Kelly W. Muir, MD Kateki Vinod, MD John T. Lind, MD Martha M. Wright, MD, American Glaucoma Society Representative Tianjing Li, MD, MHS, PhD, Consultant, Cochrane Eyes and Vision US Project Steven L. Mansberger, MD, MPH, Methodologist We thank our partner, the Cochrane Eyes and Vision US Project, for identifying reliable systematic reviews that we cite and discuss in support of the PPP recommendations. The Preferred Practice Patterns Committee members reviewed and discussed the document during a meeting in May 2020. The document was edited in response to the discussion and comments. Preferred Practice Patterns Committee 2020 Roy S. Chuck, MD, PhD, Chair Steven P. Dunn, MD Christina J. Flaxel, MD Steven J. Gedde, MD Francis S. Mah, MD Kevin M. Miller, MD James P. Tweeten, MD David K. Wallace, MD, MPH David C. Musch, PhD, MPH, Methodologist The Primary Angle Closure Disease PPP was then sent for review to additional internal and external groups and individuals in June 2020. All those who returned comments were required to provide disclosure of relevant relationships with industry to have their comments considered (indicated with an asterisk below). Members of the PPP Panel reviewed and discussed these comments and determined revisions to the document. Academy Reviewers Board of Trustees and Committee of Secretaries* Council* General Counsel* Ophthalmic Technology Assessment Committee Glaucoma Panel* Basic and Clinical Science Course Section 10 Subcommittee Practicing Ophthalmologists Advisory Committee for Education Invited Reviewers American College of Surgeons American Glaucoma Society American Ophthalmological Society Association for Research in Vision and Ophthalmology Association of University Professors in Ophthalmology* Consumer Reports Health Choices Canadian Ophthalmological Society* European Glaucoma Society* International Council of Ophthalmology International Society of Glaucoma Surgery International Society of Refractive Surgery National Eye Institute* National Medical Association, Section on Ophthalmology North American Neuro-Ophthalmology Society* Outpatient Ophthalmic Surgery Society World Glaucoma Association* Women in Ophthalmology* Wallace L.M. Alward, MD* Ta Chen Chang, MD FINANCIAL DISCLOSURES In compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies (available at https://cmss.org/code-signers-pdf/), relevant relationships with industry are listed. The Academy has Relationship with Industry Procedures to comply with the Code (available at www.aao.org/about-preferred-practice-patterns). A majority (75%) of the members of the Glaucoma Preferred Practice Pattern Panel 2019-2020 had no related financial relationship to disclose. Glaucoma Preferred Practice Pattern Panel 2019-2020 Steven J. Gedde, MD: No financial relationships to disclose Philip P. Chen, MD: Allergan—Consultant/Advisor John T. Lind, MD: Aerie Pharmaceuticals, Allergan—Consultant/Advisor; Aerie Pharmaceuticals, Allergan—Lecture Fees, Perrigo—Grant Support Kelly W. Muir, MD: No financial relationships to disclose Kateki Vinod, MD: No financial relationships to disclose Martha M. Wright, MD: No financial relationships to disclose Tianjing Li, MD, MHS, PhD: No financial relationships to disclose Steven L. Mansberger, MD, MPH: No financial relationships to disclose Preferred Practice Patterns Committee 2020 Roy S. Chuck, MD, PhD, Chair: No financial relationships to disclose Steven P. Dunn, MD: No financial relationships to disclose Christina J. Flaxel, MD: No financial relationships to disclose Steven J. Gedde, MD: No financial relationships to disclose Francis S. Mah, MD: Abbott Medical Optics Inc., Alcon Laboratories, Allergan, Bausch + Lomb, EyePoint, Kala Pharmaceuticals, Novartis Pharmaceuticals, Ocular Science, Ocular Therapeutix, Omeros Corporation—Consultant/Advisor; Abbott Medical Optics Inc., Bausch + Lomb, Novartis Pharmaceuticals—Lecture Fees; Abbott Medical Optics Inc., Ocular Therapeutix—Grant Support, Ocular Science—Equity Owner Kevin M. Miller, MD: Alcon Laboratories, Johnson& Johnson Vision—Consultant/Advisor James P. Tweeten, MD: No financial relationships to disclose David K. Wallace, MD, MPH: No financial relationships to disclose David C. Musch, PhD, MPH, Methodologist: No financial relationships to disclose Secretary for Quality of Care Timothy W. Olsen, MD: No financial relationships to disclose Academy Staff Ali Al-Rajhi, PhD, MPH: No financial relationships to disclose Andre Ambrus, MLIS: No financial relationships to disclose Meghan Daly: No financial relationships to disclose Flora C. Lum, MD: No financial relationships to disclose Susan Garratt: No financial relationships to disclose The disclosures of relevant relationships to industry of other reviewers of the document from January to October 2020 are available online at www.aao.org/ppp. TABLE OF CONTENTS OBJECTIVES OF PREFERRED PRACTICE PATTERN GUIDELINES P36 METHODS AND KEY TO RATINGS P37 HIGHLIGHTED FINDINGS AND RECOMMENDATIONS FOR CARE P38 INTRODUCTION P39 Disease Definition P39 Disease Classification and Clinical Findings Characteristic of Primary Angle-Closure Disease P39Primary Angle-Closure Suspect P39Primary Angle Closure and Primary Angle-Closure Glaucoma P40Acute Angle-Closure Crisis P40Plateau Iris Configuration and Syndrome P40 Patient Population P40 Clinical Objectives P40 BACKGROUND P42 Prevalence P42 Risk Factors P43Demographic Characteristics P43Ocular Features P43 Natural History P43 CARE PROCESS P43 Patient Outcome Criteria P43 Diagnosis P43History P44Physical Examination P44Diagnostic Testing P46Differential Diagnosis P50 Management P50Goals P50Primary Angle-Closure Suspect P50Primary Angle Closure and Primary Angle-Closure Glaucoma P51Surgery and Postoperative Care P51Acute Angle-Closure Crisis P52Plateau Iris Configuration and Syndrome P54Follow-up Evaluation P55 Provider and Setting P55 Counseling and Referral P55 Socioeconomic Considerations P55 APPENDIX 1. QUALITY OF OPHTHALMIC CARE CORE CRITERIA P57 APPENDIX 2. INTERNATIONAL STATISTICAL CLASSIFICATION OF DISEASES AND RELATED HEALTH PROBLEMS (ICD) CODES P59 APPENDIX 3. ALGORITHM FOR THE MANAGEMENT OF PATIENTS WITH ACUTE ANGLE-CLOSURE CRISIS P60 APPENDIX 4. LITERATURE SEARCHES FOR THIS PPP P61 RELATED ACADEMY MATERIALS P61 REFERENCES P63 Primary Angle Closure Disease Preferred Practice Pattern® Background: Primary angle closure disease (PACD) is classified into several groups. Primary angle closure suspect is defined as ≥ 180 degrees of iridotrabecular contact (ITC) without intraocular pressure (IOP) elevation, peripheral anterior synechiae (PAS), or optic nerve damage. An eye with ≥ 180 degrees of ITC and elevated IOP or PAS is categorized as primary angle closure, and the additional presence of glaucomatous optic neuropathy indicates primary angle closure glaucoma. Acute angle-closure crisis (AACC) represents a sudden, marked IOP elevation with complete ITC. Plateau iris configuration is defined as a narrow angle due to an anteriorly positioned ciliary body with a deep central anterior chamber, and plateau iris syndrome is persistent ITC after laser peripheral iridotomy (LPI). Although 90% of cases of AACC present unilaterally, PACD is generally bilateral. Risk factors for PACD include Asian descent, hyperopia, older age, female gender, short axial length, and thick and anteriorly positioned crystalline lens. Rationale for Treatment: Pupillary block is involved in the pathogenesis of PACD in most cases, and is resolved with LPI. Patients experiencing AACC should receive medical treatment to lower the IOP, and LPI should subsequently be performed in both eyes. Lens extraction has also been shown to be an effective treatment in some patients with primary angle closure and primary angle closure glaucoma. Care Process: The goals of managing patients with PACD are to reverse or prevent angle closure and to control IOP to prevent glaucomatous optic nerve damage. Dark-room dynamic gonioscopy should be performed to diagnose PACD and verify improvement in angle configuration following treatment. Ultrasound biomicroscopy and anterior segment optical coherence tomography can also aid in the diagnosis of PACD. OBJECTIVES OF PREFERRED PRACTICE PATTERN® GUIDELINES As a service to its members and the public, the American Academy of Ophthalmology has developed a series of Preferred Practice Pattern® guidelines that identify characteristics and components of quality eye care. Appendix 1 describes the core criteria of quality eye care. The Preferred Practice Pattern® guidelines are based on the best available scientific data as interpreted by panels of knowledgeable health professionals. In some instances, such as when results of carefully conducted clinical trials are available, the data are particularly persuasive and provide clear guidance. In other instances, the panels have to rely on their collective judgment and evaluation of available evidence. These documents provide guidance for the pattern of practice, not for the care of a particular individual. While they should generally meet the needs of most patients, they cannot possibly best meet the needs of all patients. Adherence to these PPPs will not ensure a successful outcome in every situation. These practice patterns should not be deemed inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the best results. It may be necessary to approach different patients' needs in different ways. The physician must make the ultimate judgment about the propriety of the care of a particular patient in light of all of the circumstances presented by that patient. The American Academy of Ophthalmology is available to assist members in resolving ethical dilemmas that arise in the course of ophthalmic practice. Preferred Practice Pattern® guidelines are not medical standards to be adhered to in all individual situations. The Academy specifically disclaims any and all liability for injury or other damages of any kind, from negligence or otherwise, for any and all claims that may arise out of the use of any recommendations or other information contained herein. References to certain drugs, instruments, and other products are made for illustrative purposes only and are not intended to constitute an endorsement of such. Such material may include information on applications that are not considered community standard, that reflect indications not included in approved U.S. Food and Drug Administration (FDA) labeling, or that are approved for use only in restricted research settings. The FDA has stated that it is the responsibility of the physician to determine the FDA status of each drug or device he or she wishes to use, and to use them with appropriate patient consent in compliance with applicable law. Innovation in medicine is essential to ensure the future health of the American public, and the Academy encourages the development of new diagnostic and therapeutic methods that will improve eye care. It is essential to recognize that true medical excellence is achieved only when the patients' needs are the foremost consideration. All Preferred Practice Pattern® guidelines are reviewed by their parent panel annually or earlier if developments warrant and updated accordingly. To ensure that all PPPs are current, each is valid for 5 years from the "approved by" date unless superseded by a revision. Preferred Practice Pattern guidelines are funded by the Academy without commercial support. Authors and reviewers of PPPs are volunteers and do not receive any financial compensation for their contributions to the documents. The PPPs are externally reviewed by experts and stakeholders, including consumer representatives, before publication. The PPPs are developed in compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies. The Academy has Relationship with Industry Procedures (available at www.aao.org/about-preferred-practice-patterns) to comply with the Code. Appendix 2 contains the International Statistical Classification of Diseases and Related Health Problems (ICD) codes for the disease entities that this PPP covers. Appendix 3 has an algorithm for the management of patients with acute angle-closure crisis (AACC). The intended users of the Primary Angle Closure PPP are ophthalmologists. Preferred Practice Pattern® guidelines should be clinically relevant and specific enough to provide useful information to practitioners. Where evidence exists to support a recommendation for care, the recommendation should be given an explicit rating that shows the strength of evidence. To accomplish these aims, methods from the Scottish Intercollegiate Guideline Network1Scottish Intercollegiate Guidelines Network (SIGN) SIGN 50: A guideline developer's handbook. SIGN, Edinburgh2015Available at: www.sign.ac.ukDate accessed: November , 2020Google Scholar (SIGN) and the Grading of Recommendations Assessment, Development and Evaluation2Guyatt GH Oxman AD Vist GE et al.Grade: An emerging consensus on rating quality of evidence and strength of recommendations.BMJ. 2008; 336: 924-926Crossref PubMed Google Scholar (GRADE) group are used. GRADE is a systematic approach to grading the strength of the total body of evidence that is available to support recommendations on a specific clinical management issue. Organizations that have adopted GRADE include SIGN, the World Health Organization, the Agency for Healthcare Research and Policy, and the American College of Physicians.3GRADE working group Organizations that have endorsed or that are using grade.Available at: www.gradeworkinggroup.org/Date accessed: November , 2020Google Scholar♦All studies used to form a recommendation for care are graded for strength of evidence individually, and that grade is listed with the study citation.♦To rate individual studies, a scale based on SIGN1Scottish Intercollegiate Guidelines Network (SIGN) SIGN 50: A guideline developer's handbook. SIGN, Edinburgh2015Available at: www.sign.ac.ukDate accessed: November , 2020Google Scholar is used. The definitions and levels of evidence to rate individual studies are as follows:Tabled 1I++High-quality meta-analyses, systematic reviews of randomized controlled trials (RCTs), or RCTs with a very low risk of biasI+Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of biasI-Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of biasII++High-quality systematic reviews of case-control or cohort studiesHigh-quality case-control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causalII+Well-conducted case-control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causalII-Case-control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causalIIINonanalytic studies (e.g., case reports, case series) Open table in a new tab ♦Recommendations for care are formed based on the body of the evidence. The body of evidence quality ratings are defined by GRADE2Guyatt GH Oxman AD Vist GE et al.Grade: An emerging consensus on rating quality of evidence and strength of recommendations.BMJ. 2008; 336: 924-926Crossref PubMed Google Scholar as follows:Tabled 1Good qualityFurther research is very unlikely to change our confidence in the estimate of effectModerate qualityFurther research is likely to have an important impact on our confidence in the estimate of effect and may change the estimateInsufficient qualityFurther research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate Any estimate of effect is very uncertain Open table in a new tab ♦Key recommendations for care are defined by GRADE2Guyatt GH Oxman AD Vist GE et al.Grade: An emerging consensus on rating quality of evidence and strength of recommendations.BMJ. 2008; 336: 924-926Crossref PubMed Google Scholar as follows:Tabled 1Strong recommendationUsed when the desirable effects of an intervention clearly outweigh the undesirable effects or clearly do notDiscretionary recommendationUsed when the trade-offs are less certain—either because of low-quality evidence or because evidence suggests that desirable and undesirable effects are closely balanced Open table in a new tab ♦The Highlighted Findings and Recommendations for Care section lists points determined by the PPP Panel to be of particular importance to vision and quality of life outcomes.♦All recommendations for care in this PPP were rated using the system described above. Ratings are embedded throughout the PPP main text in italics.♦Literature searches to update the PPP were undertaken in March 2019 and June 2020 in the PubMed and Cochrane databases. Complete details of the literature searches are available in Appendix 4. Understanding the current disease definition is important in the management of the primary angle-closure disease (PACD) spectrum. Modern classification includes:♦Primary angle-closure suspect (PACS): ≥180 degrees iridotrabecular contact (ITC), normal intraocular pressure (IOP), and no optic nerve damage♦Primary angle closure (PAC): ≥180 degrees ITC with peripheral anterior synechiae (PAS) or elevated IOP but no optic neuropathy♦Primary angle-closure glaucoma (PACG): ≥180 degrees ITC with PAS, elevated IOP, and optic neuropathy♦Acute angle-closure crisis (AACC): occluded angle with symptomatic high IOP♦Plateau iris configuration: narrow angle due to an anteriorly positioned ciliary body, with deep central anterior chamber♦Plateau iris syndrome: narrow angle due to an anteriorly positioned ciliary body, with deep central anterior chamber, and any ITC persisting after patent peripheral iridotomy Common risk factors for PACD include Asian descent, hyperopia, older age, female gender, short axial length, and thick and anteriorly positioned crystalline lens. Dark-room dynamic gonioscopy should be performed to diagnose PACD and to verify improvement in angle configuration following treatment. Ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT) can also aid in the diagnosis of angle closure, but only UBM and dynamic gonioscopy can identify the etiology of plateau iris. The clinical signs and symptoms of AACC include pressure-induced corneal edema (experienced as blurred vision and occasionally as halos around lights), a mid-dilated pupil, vascular congestion (i.e., conjunctival and episcleral), eye pain, headache, and nausea/vomiting. Patients experiencing AACC should receive medical treatment, including aqueous suppressants, parasympathomimetics, and osmotic agents, if necessary, to lower the IOP acutely and relieve symptoms. This should be followed by laser iridotomy or iridectomy. After addressing the episode of AACC, it is important to perform laser iridotomy in the fellow eye when indicated. Lens extraction is an effective treatment for some patients with PAC and PACG. Primary angle-closure disease (PACD) is appositional or synechial closure of the anterior chamber angle. Experts now recognize multiple mechanisms for PACD. Pupillary block is a key element in the pathogenesis of most instances of PACD.4Anderson DR Jin JC Wright MM The physiologic characteristics of relative pupillary block.Am J Ophthalmol. 1991; 111: 344-350Abstract Full Text PDF PubMed Google Scholar, 5Tiedeman JS A physical analysis of the factors that determine the contour of the iris.Am J Ophthalmol. 1991; 111: 338-343Abstract Full Text PDF PubMed Google Scholar, 6Jin JC Anderson DR The effect of iridotomy on iris contour.Am J Ophthalmol. 1990; 110: 260-263Abstract Full Text PDF PubMed Google Scholar The pressure in the posterior chamber is higher than in the anterior chamber due to impairment of aqueous humor flow from the posterior chamber at the pupil, causing an anterior bowing of the iris that crowds the angle in predisposed eyes. Additional mechanisms that contribute to PACD include the relative position and thickness of the ciliary body, the location of the iris insertion into the ciliary body, and the volume of the iris. Certain anatomical features can increase this pressure disparity between the two chambers (e.g., pupil dilation and the crystalline lens size, shape, position, and thickening with age), which then results in iris apposition to the anterior chamber angle structures. In a minority of cases, this can happen acutely, resulting in acute angle-closure crisis (AACC). Prolonged or repeated contact of the peripheral iris with the trabecular meshwork may lead to functional damage of the trabecular meshwork and the development of peripheral anterior synechiae (PAS). Primary angle-closure disease may not initially be associated with elevated intraocular pressure (IOP) or glaucomatous optic neuropathy, and it may occur in either an acute or chronic form. Secondary forms of angle closure can also occur (e.g., iridocorneal endothelial syndrome, inflammation, or neovascularization). This Preferred Practice Pattern (PPP) focuses on PACD, and the management of other secondary forms of angle closure glaucoma (e.g., neovascular glaucoma) is not discussed. Primary angle-closure disease is generally bilateral, although 90% of AACC are unilateral.7Seah SK Foster PJ Chew PT et al.Incidence of acute primary angle-closure glaucoma in Singapore. An island-wide survey.Arch Ophthalmol. 1997; 115: 1436-1440Crossref PubMed Google Scholar, 8Friedman DS Gazzard G Foster P et al.Ultrasonographic biomicroscopy, scheimpflug photography, and novel provocative tests in contralateral eyes of Chinese patients initially seen with acute angle closure.Arch Ophthalmol. 2003; 121: 633-642Crossref PubMed Scopus (111) Google Scholar Patients with PACD and those at risk may be categorized as follows (see Table 1):TABLE 1Clinical Findings That Define Patients Seen With Primary Angle-Closure DiseasePrimary Angle-Closure SuspectPrimary Angle ClosurePrimary Angle-Closure Glaucoma≥180 degrees ITCPresentPresentPresentElevated IOP or PASAbsentPresentPresentOptic nerve damageAbsentAbsentPresentIOP = intraocular pressure; ITC = iridotrabecular contact; PAS = peripheral anterior synechiae Open table in a new tab IOP = intraocular pressure; ITC = iridotrabecular contact; PAS = peripheral anterior synechiae Iridotrabecular contact (ITC), as observed on gonioscopy without compression, is defined as the iris appearing to touch the anterior chamber angle at the posterior pigmented trabecular meshwork or more anterior structures. The extent of iridotrabecular contact required to diagnose an eye as having PACD has been the subject of debate. Consensus suggests that a person with 180 degrees or more of ITC on dark-room gonioscopy is at risk of primary angle-closure glaucoma (PACG) or an AACC9Weinreb RN Friedman DS Angle closure and angle closure glaucoma: Reports and consensus statements of the 3rd global AIGS consensus meeting on angle closure glaucoma. Kugler Publications, The Netherlands2006Google Scholar, 10Leung CK Cheung CY Li Ft et al.Dynamic analysis of dark-light changes of the anterior chamber angle with anterior segment OCT.Invest Ophthalmol Vis Sci. 2007; 48: 4116-4122Crossref PubMed Scopus (70) Google Scholar An eye with this amount or more of ITC, no PAS, and normal IOP is considered a primary angle-closure suspect (PACS).9Weinreb RN Friedman DS Angle closure and angle closure glaucoma: Reports and consensus statements of the 3rd global AIGS consensus meeting on angle closure glaucoma. Kugler Publications, The Netherlands2006Google Scholar A study conducted in southern India found that about one in four untreated PACS subjects in this population developed elevation in IOP or PAS over 5 years.11Thomas R Parikh R Muliyil J Kumar RS Five-year risk of progression of primary angle closure to primary angle closure glaucoma: A population-based study.Acta Ophthalmol Scand. 2003; 81: 480-485Crossref PubMed Scopus (123) Google Scholar, 12Thomas R George R Parikh R et al.Five year risk of progression of primary angle closure suspects to primary angle closure: A population based study.Br J Ophthalmol. 2003; 87: 450-454Crossref PubMed Scopus (156) Google Scholar However, a large prospective population-based study in Zhongshan, China found only 4% of PACS eyes reached the same endpoint over 6 years.13He M Jiang Y Huang S et al.Laser peripheral iridotomy for the prevention of angle closure: A single-centre, randomised controlled trial.Lancet. 2019; 393: 1609-1618Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar Further longitudinal studies in diverse ethnoracial populations are needed. Any eye that has at least 180 degrees of ITC and an elevated IOP or PAS with no secondary cause for the PAS is classified as having PAC. The presence of high IOP and/or PAS suggests that ITC noted during gonioscopy may cause permanent histopathologic changes to the eye.14Hamanaka T Kasahara K Takemura T Histopathology of the trabecular meshwork and schlemm's canal in primary angle-closure glaucoma.Invest Ophthalmol Vis Sci. 2011; 52: 8849-8861Crossref PubMed Scopus (46) Google Scholar When glaucomatous optic neuropathy is present (as defined in the Primary Open-Angle Glaucoma PPP15American Academy of Ophthalmology Glaucoma Panel Preferred Practice Pattern® Guidelines. Primary open-angle glaucoma. American Academy of Ophthalmology, San Francisco, CA2015Google Scholar), the eye has progressed from PAC to PACG. Eyes with intermittent PACG may have normal IOP between episodes of elevated IOP that cause optic neuropathy.16Lowe RF Clinical types of primary angle closure glaucoma.Aust N Z J Ophthalmol. 1988; 16: 245-250Crossref PubMed Scopus (0) Google Scholar If the anterior chamber angle is obstructed suddenly, the IOP can rise rapidly to high levels. The characteristic clinical signs and symptoms include pressure-induced corneal edema (experienced as blurred vision and occasionally as halos around lights), a mid-dilated pupil, lens opacities (glaucomflecken), vascular congestion (i.e., conjunctival and episcleral), eye pain, headache, and nausea/vomiting. This condition is considered an AACC and may be self-limited or may recur. Untreated, this entity may cause permanent vision loss or blindness. The fellow eye is also at high risk of AACC. Plateau iris configuration refers to eyes that have a gonioscopic appearance of the peripheral iris closely apposed to the angle despite a deep central anterior chamber.17Pavlin CJ Ritch R Foster FS Ultrasound biomicroscopy in plateau iris syndrome.Am J Ophthalmol. 1992; 113: 390-395Abstract Full Text PDF PubMed Google Scholar, 18Ritch R Plateau iris is caused by abnormally positioned ciliary processes.J Glaucoma. 1992; 1: 23-26Crossref Google Scholar The etiology, anterior rotation of the ciliary body, can be discerned using dynamic gonioscopy or ultrasound biomicroscopy (UBM) but not anterior segment optical coherence tomography (AS-OCT). Nearly one-third of PAC eyes treated with iridotomy have an angle that retains substantial ITC19Quigley HA Long-term follow-up of laser iridotomy.Ophthalmology. 1981; 88: 218-224Abstract Full Text PDF PubMed Google Scholar, 20He M Friedman DS Ge J et al.Laser peripheral iridotomy in primary angle-closure suspects: Biometric and gonioscopic outcomes: The Liwan eye study.Ophthalmology. 2007; 114: 494-500Abstract Full Text Full Text PDF PubMed Scopus (129) Google Scholar, 21He M Friedman DS Ge J et al.Laser peripheral iridotomy in eyes with narrow drainage angles: Ultrasound biomicroscopy outcomes. The Liwan eye study.Ophthalmology. 2007; 114: 1513-1519Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar, 22Kumar RS Tantisevi V Wong MH et al.Plateau iris in asian subjects with primary angle closure glaucoma.Arch Ophthalmol. 2009; 127: 1269-1272Crossref PubMed Scopus (56) Google Scholar, 23Kumar G Bali SJ Panda A et al.Prevalence of plateau iris configuration in primary angle closure glaucoma using ultrasound biomicroscopy in the Indian population.Indian J Ophthalmol. 2012; 60: 17