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How to Co-Manage Narrow Angle Patients with an Ophthalmologist (with Referral Template)

Aug 12, 2021
11 min read

The topic of narrow angles is not a common one among eyecare providers and can be overlooked on many routine eye exams. Evaluation and management of narrow angle patients can be difficult due to various presentations of the condition and potential sequelae of angle closure and angle closure glaucoma. As many patients can be asymptomatic, a careful examination of angle structures and anatomy is important for patients of all ages. A detailed ocular examination is important to rule out those patients at risk for narrow angles or angle closure.

In this article, we will discuss the anatomy of the anterior chamber angle, relationship between narrow angles and glaucoma, and procedure of referring patients.

Defining a narrow angle

A narrow or occludable angle is defined as an anatomical disposition in which the trabecular meshwork cannot be seen in more than 180 degrees via gonioscopy.7 Angle closure can be categorized into primary angle closure suspect, primary angle closure, and angle closure glaucoma.

Some risk factors4,10 for occludable angles include:

  • Gender: Females have a higher predisposition than males.
  • Prescriptions: Hyperopes tend to have shorter axial length as compared to emmetropes and myopes.
  • Increase in lens thickness: As cataract develops, the lens thickens and pushes the iris forward leading to narrowing of the angle.
  • Increased age: Elderly patients have increased risk.
  • Ethnicity: Inuit and East Asian populations are at higher risk.
  • Family history: Those with family history of occludable angles may be higher risk
  • Systemic medications: Use of topiramate, anticholinergics, and sympathomimetics can increase risk.

Types of angle closure

Angle closure4,7 is classified as primary or secondary angle closure, former commonly due to anatomical disposition, later due to known pathology.

  • Primary angle closure can be due to:
    • Pupillary block where apposition of lens and posterior iris leads to blockage of aqueous outflow.
    • Plateau iris where the iris root inserts anteriorly.
  • Secondary angle closure is due to pathology. Some conditions include:
    • Cataracts.
    • Neovascularization.
    • Membrane obstruction.
    • Developmental abnormality.

Below is a quick cheat sheet for the three most common conditions4,7

1) Angle closure suspect

  • Symptoms: patient is usually asymptomatic
  • Sign: narrow angles or 180 degrees of iridotrabecular apposition without glaucomatous findings

2) Angle closure4,7

  • Etiology: primary vs secondary (as listed above)
  • Symptoms: patient may be asymptomatic or have blurry vision
    • in acute cases, patient will experience vision loss, pain, nausea and photophobia
  • Sign: narrow or closed angle, elevated IOP, corneal edema, fixed dilated pupil, peripheral anterior synechiae (PAS) may be present

3) Angle closure glaucoma4,7

  • Symptoms: blurry vision, pain, watery eyes, photophobia, halos around lights, nausea, vomiting
  • Signs: corneal edema, fixed dilated pupil, IOP between 50 to 70 mmHg with glaucomatous damage, PAS may or may not be present

Narrow angle patients may be asymptomatic therefore it is important to take a thorough history and examination to identify patients at risk.

Assessment of anterior chamber angle

The iris inserts into the anterior side of the ciliary body and separates the aqueous compartments into the anterior and posterior chamber. Aqueous humor is formed by the ciliary processes, passes from the posterior chamber into the anterior chamber via the pupil, and then leaves the eye through the anterior chamber angle. The anterior chamber is defined as the angle formed by the iris and the cornea.

Shown in Figure 1, the structures of the angle (from posterior and anterior) are as follows:


Figure 1

Figure 2, below, is a gonioscopy view of angle structures.3