Primary Angle Closure: What Ophthalmology Residents Should Know | Eyes On Eyecare

Primary Angle Closure: What Ophthalmology Residents Should Know

Our office sees patients with narrow angles on an almost daily basis. Here's what you need to know about diagnosing and treating this common condition.

5.0 (2 ratings)
Updated May 21, 2020
45min
1 quiz
Course Contents
What You'll Learn
  • Understand the clinical, economic, and social burden of primary angle closure
  • Learn the main options for treatment of primary angle closure
  • Practice techniques for taking patient history and documenting results
  • Learn gonioscopy essentials

Introduction and Quiz

One of the most common types of patients we see in our offices on a daily basis is the patient with narrow angles. This patient typically falls somewhere on the spectrum of angle closure—they are either on one end of the spectrum as a primary angle closure suspect (PACS), or further along and they have definitive primary angle closure (PAC), or even further along, and have developed primary angle closure glaucoma (PACG). And, hopefully for that patient, the first time you see them isn’t at the farthest end of the spectrum, in acute angle closure crisis (AACC).

A typical patient that we see in our office is a 54-year-old male with high blood pressure who presents for an initial eye exam with the complaint of mild blurry vision at near. Most of his exam is normal, he’s 20/20 with correction at near, his refraction is hyperopic +2.50 OD//+3.00 OS, he has intraocular pressure (IOP) in the high teens, say 18//19 mmHg, and early stage nuclear sclerotic cataracts. On further examination you perform gonioscopy and find an angle with only bare trabecular meshwork seen (Figure 1), and upon compression gonioscopy, no further angle structures are seen. You perform a non-dilated exam of the optic nerves and see a sharp healthy appearing optic nerve. Ultimately, your impression is that this patient has anatomically narrow angles.

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Figure 1: Gonioscopy showing bare trabecular meshwork.

The next step is the challenge: what do you do next? Would you monitor this patient at every few month intervals? Would you start them on a topical antihypertensive eyedrop? Would you refer for laser peripheral iridotomy (LPI)? Would you refer for lens extraction?

Now what if the parameters of the case changed, and the patient was of Asian descent? Or female? Or younger—say, 35 years old? What if the patient had retinal pathology like diabetic retinopathy, or a history of a retinal detachment? What if they have a family history of angle closure glaucoma? Would any of these parameters change your plan?

Primary Angle Closure: What Ophthalmology Residents Should Know

10 Questions

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The Big Picture: Disease Effects and Staging

Clinical, Economic, and Social Burden

Let’s step back for a minute and learn why it’s important to understand how to diagnose and manage patients on the angle closure spectrum. I like to think of ocular conditions in terms of the condition’s clinical, economic, and social burden to the patient.

In terms of clinical burden: we know that the prevalence of glaucoma on a whole is ever-increasing. In 2014 the global prevalence was reported to be ~3.5% of the global population.2,3 The total number of patients diagnosed with glaucoma, both open and closed angle glaucoma, in 2010 was 60.5 million people, increasing to 79.6 million in 2020, and estimated to be 111.8 million total patients with open and closed angle glaucoma worldwide.2,3 When comparing open angle and closed angle glaucoma, closed angle glaucoma comprises approximately ÂĽ of the total population of glaucoma worldwide both in 2010 and now in 2020 (Figure 2).2 However, both subgroups have an equal number of patients who go blind, lending to the significant clinical burden of the percentage of the total PACG patients who go blind (Figure 2).2

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Figure 2: LEFT – total global population of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG); RIGHT – number of patients bilaterally blind with POAG and PACG2

Our priority in caring for our patients is the burden that they experience. Typically, the patient burden is three-fold: the decompensation of the quality of life, formal costs such as insurance costs, and informal costs such as homecare aides or visiting nursing services. And all of these affect our efforts to manage their disease.

One study reviewing over 77,000 patient from 1996-2002 reported that even when controlling for other variables like comorbidities and demographics, blindness was found to use an excess of $2000.00, and 4 times the amount of extra days of informal care when compared to visually impaired patients.4 Now if you multiply that over a 10-year span (considering PACG spectrum patients have a chronic condition), this cost can come out to about $20,000$ and 40 times the amount of informal care when compared to a visually impaired patient. They concluded that blindness is the primary driving force in informal care needs for the patient. The goal therefore on a daily basis in clinic is taking this information as a basis of need for appropriate diagnosis and management as to prevent the progression to blindness the best we can.

Once we understand the burden of the disease, screening and diagnosing the condition is the next step. When screening for the disease there are some higher alert groups to look out for when assessing risk factors for the disease. Patient who are at risk for being on the primary angle closure spectrum include those who are: older in age, Asian/Inuit descent (87% of ACG), female (70% of ACG), and hyperopic patients.2,3 And with the increasing aging and diversifying population (especially in our urban centers), we will likely be seeing more patients on the angle closure spectrum in our offices.

Staging

You should also know the definition for the different stages along the spectrum of primary angle closure. The American Academy of Ophthalmology publishes their Preferred Practice Patterns for different ocular conditions every few years. Here they have established a staging guideline for Primary Angle Closure patients (Figure 4).5

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Figure 4: Preferred Practice Patterns of Primary Angle Closure spectrum patients; PACS: primary angle closure suspect, PAC: primary angle closure, PACG: primary angel closure glaucoma, APAC: acute primary angle closure, AACC: acute angle closure crisis, ITC: iridotrabecular contact, PAS: peripheral anterior synechiae.

All patients on the spectrum of angle closure have at least 180° degrees of iridotrabecular contact (ITC). Starting at the lower end of the spectrum being a primary angle closure suspect (PACS) is defined as having at least 180° ITC, but normal IOP, no peripheral anterior synechiae (PAS), and no optic neuropathy (ON). The patient is defined as having primary angle closure (PAC), when the IOP advances and is elevated, or the patient starts to develop PAS, but still has no ON. The patient then becomes a primary angle closure glaucoma (PACG) patient when they have the previous findings but also ON. The patient is in true acute angle closure crisis (AACC) when the high IOP is symptomatic and their angle is completely occluded. Having a consistent way of defining patients along this spectrum helps for universal and standardized diagnosis globally.


Diagnosing Primary Angle Closure

Patient History and Exam

Once you have identified your risk factors in an individual patient, taking a relevant history of present illness and comprehensive exam should be obtained. As we all know patients can range, symptom-wise, anywhere from being asymptomatic to having blurry vision, pain, halos, tearing, and/or intermittent redness. Family history can also be contributory. A comprehensive exam should include refraction, looking for hyperopia. Assessing the patient’s Von Herick’s angle, using a narrow slit beam shone 60° at the limbus can give a gross idea angle narrowing as a possibility (Figure 5).6

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Figure 5: With two parallel light beams shone at a 60° at the limbus with the anterior beam being the corneal section and posterior beam hitting the anterior aspect of the iris. Between these beams is an optically black space. This space when measured in comparison to the width of the corneal section can be graded (Von Herick’s grading). If this band is approximately < ½ section of the corneal band thickness the angle should be further inspected.

Additionally, you should examine the patient’s lens status: whether the patient is phakic, pseudophakic, or aphakic, and how advanced their cataract is, if they have one. An optic nerve exam or retinal exam can potentially be performed non-dilated if you have concern of angle closure presence.

Gonioscopy

Most important in examining a patient with possible angle closure risk is gonioscopy.

Gonioscopy is currently the gold standard, as it is the quickest and most cost-effective screening tool we have for angle diagnoses. In 1907 Dr. Trantas (yes, of Trantas dots) was the first to examine the angle using his finger as a scleral depressor at the limbus while using a direct ophthalmoscope to view the angle. He did this to bypass total internal reflection. The anterior chamber configuration produces total internal reflection of light rays at the tear-air interface, thus disabling us from viewing a patient’s anterior angle with the naked eye.7

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Figure 6: Total internal reflection of the anterior chamber angle.

Direct gonioscopy

There are different types of gonioscopy. One type of gonioscopy is direct gonioscopy, where the angle is viewed directly at the mirror you are viewing. Examples of direct gonioscopy lenses include a Koeppe lens, which is used most commonly used in exams under anesthesia, the Swans-Jacobs lens (Figure 7), is most commonly used to perform angle-based surgeries, and a few others, such as the Barkan, Richards, and Wurst lens.

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Figure 7: Swans-Jacob’s direct gonioscopy lens; anterior chamber angle viewed through a Swan Jacob’s lens of an iStent device

The advantages of using direct gonioscopy include providing a larger wide-angle view of the anterior chamber angle, simultaneously viewing of both eyes as when using Koeppe lenses for exams under anesthesia (for example with an infant or noncooperative patient), and for use with angle-based surgery. Some disadvantages include the bulkiness of these lenses requiring an external illuminating source and microscope as well as requiring a coupling agent.

Indirect gonioscopy

Indirect gonioscopy, where the angle is indirectly viewed opposite the mirror in view, is likely more familiar, and the form that is used most often in-office. The different types of lenses include Goldmann, Possner (Figure 8), Zeiss, and Sussman. I personally use the Possner as it feels less bulky, and is easier to manipulate at the slit lamp in my hands.