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Glaucoma Management


How to Work Up a Glaucoma Suspect

Each glaucoma is unique but a common examination routine can serve most clinicians well.

Kathleen A. Lamping, MD
Cleveland

Glaucoma affects anyone, independent of age, sex or race, so any patient who comes into your office should be considered a glaucoma suspect. As the second leading cause of blindness in the United States, glaucoma is the third most common reason for visits to the ophthalmologist.1 Obviously not every patient is followed the same way, or has the same risk factors for developing glaucoma. After you take a comprehensive medical history and perform an ophthalmic examination, certain risk factors will become clear.2

Although the term “glaucoma suspect” implies that the patient has the potential for developing primary open-angle glaucoma, it’s important to identify patients at risk for angle closure and secondary glaucomas. This article attempts to clarify the diagnoses and follow-up for these patients.

Risk Factors for POAG
The incidence of developing primary open angle glaucoma is probably proportional to the number of risk factors. (See Table 1) Patients at risk for primary open-angle glaucoma (POAG) are adults who have normal open angles and no other known etiology for glaucoma. They may be suspect based on the appearance of the optic nerve, regardless of the intraocular pressure (IOP).

Figure 1. Asymmetric disc cupping.

A suspicious optic nerve may manifest as an enlarged cup-to-disc ratio or asymmetric disc cupping (See Figure 1). Focal abnormalities of the neural rim and optic disc hemorrhage may be signs of glaucoma and glaucomatous damage. A careful, red-free examination of the optic nerve may reveal abnormalities of the nerve fiber layer.

A known risk factor is an elevated IOP; any patient with a pressure higher than 22 mmHg should have a baseline optic nerve evaluation and a baseline threshold automated visual field. African-Americans are at particular risk for developing POAG.3 The disease appears at an earlier age, and seems more aggressive and more difficult to control in these patients than in those of other races.

Those with a family history of glaucoma are at considerable risk to develop the disease themselves. However, any patient with a family history of glaucoma is at a higher risk for developing the disease, independent of race. Patients whose close relatives have lost vision due to glaucoma must be followed carefully. All of these patients need baseline visual-field testing and optic nerve evaluation.

Age is another risk factor for glaucoma: 5 percent of patients over 75 years of age have glaucoma. Patients more than 70 years of age, therefore, should be followed at least once yearly, even if there are no other known risk factors. Relative risk factors include cardiovascular disease, diabetes, migraine headaches, hypertension and vasospasm. Myopia may also be a relative risk factor.

Management
Consistent, thorough follow-up, in the form of periodic IOP measurements and evaluation of the optic nerve and the visual field to determine change or progression, is considered the standard of care for glaucoma suspects.

 Table 1. Open-Angle Glaucoma—Primary
Strong Risk Factors  
  •  Elevated intraocular pressure
  • Advanced age
  • African-American descent
  • Family history of glaucoma, particularly blindness
 Possible Risk Factors
  • Cardiovascular disease
  • Migraine headache Myopia
  • Systemic hypertension  
  • Vasospasm

 Table 2. Open-Angle Glaucoma—Secondary
Commonly Seen Causes
  • Pseudoexfoliation syndrome
  • Pigmentary dispersion
  • Chronic steroid usage
  • Topical
  • Inhaled 


Careful evaluation of the optic nerve for signs of progression is the most objective way to monitor glaucoma. Obtaining a baseline stereoscopic optic nerve photography is necessary in all glaucoma suspects. On each subsequent visit, compare the optic nerve to this original photograph to determine if glaucomatous changes have occurred. Optic nerve fiber layer analysis may be another useful modality.4

Each glaucoma suspect requires a baseline threshold automated visual field. Subsequent visual fields should have the same parameters as the baseline field. An initial visual field that appears abnormal should be repeated, especially if the optic nerve appears healthy. Patients undergo a “learning curve” and often early field loss is not reproducible.

Each subsequent visit varies for every patient, depending on the appearance of the optic nerve, as well as the number of additional risk factors. These patients should be seen at least every three to 18 months; some clinicians prefer a six- to 12-month follow-up.

A dilated examination with particular emphasis on stereoscopic disc evaluation is necessary every three to 18 months, along with tension applanation. Automated threshold visual field testing should be performed every six to 18 months, depending on the clinical status and stability.

Figure 2. Pseudoexfoliation of the anterior lens capsule.

Risk Factors for Secondary Open-angle Glaucoma
The differential diagnosis of secondary open-angle glaucoma is extensive. Many of these conditions are diagnosed by the prior medical and ophthalmic history. In a general ophthalmic practice, the practitioner must be aware of pseudoexfoliation syndrome (See Figure 2) and pigmentary dispersion.

Patients with a history of chronic topical, systemic or inhaled steroid use should be followed as glaucoma suspects as well. If these patients have a family history of glaucoma, they may be at particular risk. (See Table 2)

If the tension applanation is less than or equal to 22 mmHg, then these patients require baseline optic nerve evaluation, preferably by stereoscopic optic disc photography, which is the best method for evaluation of progression. A baseline threshold visual field is also important. These patients should be followed similarly to primary open-angle glaucoma suspects.

Table 3. Angle Closure Suspect—Primary
History
  • Headache
  • Eye pain especially if associated with visual obscurations
 Ocular Examination
  • Hyperopia
  • Shallow anterior chamber by slit lamp examination
  • Occludable angle by gonioscopy

Table 4. Angle Closure Glaucoma—Secondary
Commonly Seen Causes
  • Neovascular Gglaucoma
  • Uveitis
  • Lens induced  


Risk Factors, Primary Angle-closure
Patients suspected of primary angle-closure glaucoma are diagnosed by gonioscopy; however, not every patient requires gonioscopy. We are all familiar with the classic symptoms of acute angle closure (ocular pain, significant visual loss, nausea and vomiting), but symptoms of subacute attacks may be misdiagnosed.

Subacute attacks may masquerade as migraine headaches, sinusitis, conjunctivitis or amaurosis fugax. Any patient complaining of headache or eye pain requires gonioscopy. Maintain a high index of suspicion for any patient complaining of vague eye pain or headache, especially associated with visual obscurations.

Patients who have moderate to advanced hyperopia are more likely to develop angle closure. If the slit lamp examination suggests a narrow angle then gonioscopy is required. (See Table 3)

Management
Laser iridectomy is the ultimate treatment for angle closure, either acute or subacute. Topical miotics do not prevent attacks and may actually increase the risk for angle closure. Prophylactic iridectomy may be required in patients with “occludable” angles, though these may be difficult to determine with certainty. When the status of the angles is ambiguous, you may consider referral to a glaucoma specialist. At the very least, these patients should be advised as to the symptoms of angle closure and to avoid both over-the-counter and prescribed anticholinergic drugs.

Risk Factors for Secondary Angle-closure
Patients with secondary angle-closure usually present with either a narrow angle or synechial closure from another mechanism. Secondary narrow angles often are due to a lens abnormality, such as phacodonisis or subluxation.

Many patients with pseudoexfoliation syndrome have narrow angles secondary to loose zonules. Other causes of secondary synechial closure are uveitis, neovascular glaucoma, trauma or the iridocorneal-endothelial syndromes. Correction of the underlying etiology is key to managing these patients.

Neovascular glaucoma (See Figure 3) is a more common etiology of secondary angle closure glaucoma. A careful history is critical in managing these patients. In particular, patients with a history of vascular ischemia secondary to diabetes, vascular occlusion, or other etiologies require high-magnification slit lamp examination, gonioscopy and a high index of suspicion for new vessels appearing in the angle or on the iris.