Ratings of importance to the care process (A-C) and ratings of strength of evidence (I-III) are defined at the end of the "Major Recommendations" field.
Diagnosis
The comprehensive initial glaucoma suspect evaluation (history and physical examination) includes all components of the comprehensive adult medical eye evaluation in addition to and with special attention to those factors that specifically bear upon the diagnosis, course, and treatment of primary open-angle glaucoma (POAG).
Evaluation of Visual Function
Self-reported functional status or difficulty with vision can be assessed either by patient complaints or by specific questionnaires including the National Eye Institute - Visual Function Questionnaire-25 (Gutierrez et al., 1997; Lee et al., 1998; Parrish et al., 1997; Sherwood et al., 1998; Wilson et al., 1998). [A:III]
Ophthalmic Evaluation
History
- Ocular, [A:III] family (Dielemans et al., 1994; Tielsch et al., 1994; Wolfs et al., 1998), [A:II] and systemic history (e.g., asthma, migraine headache, vasospasm). [A:III] The severity and outcome of glaucoma in family members, including history of visual loss from glaucoma, should be obtained during initial evaluation (Tielsch et al., 1994; Wolfs et al., 1998). [B:III]
- Review of pertinent records [A:III] with particular reference to the intraocular pressure (IOP) and the status of the optic nerve and visual field [A:III]
- Ocular and systemic medications (e.g., corticosteroids) and known local or systemic intolerance to ocular or systemic medications [A:III]
- Ocular surgery [A:III]
Visual Acuity Measurement
Visual acuity with current correction (the power of the present correction recorded) at distance and, when appropriate, at near should be measured. [A:III]
Pupil Examination
The pupils are examined for reactivity and an afferent pupillary defect (Kohn, Moss, & Podos, 1979; Brown et al., 1987; Kerrison et al., 2001). [B:II]
Anterior Segment Examination
A slit-lamp biomicroscopic examination of the anterior segment can provide evidence of physical findings associated with narrow angles, such as shallow peripheral anterior chamber depth and crowded anterior chamber angle anatomy (Foster et al., 2000; Van Herick, Shaffer, & Schwartz, 1969), corneal pathology, or a secondary mechanism for elevated IOP such as pseudoexfoliation (exfoliation syndrome), pigment dispersion with iris transillumination defects, iris and angle neovascularization, or inflammation. [A:III]
Intraocular Pressure Measurement
Intraocular pressure is measured in each eye, preferably by Goldmann applanation tonometry, before gonioscopy or dilation of the pupil (Whitacre & Stein, 1993). [A:III]
Gonioscopy
The diagnosis of POAG requires careful evaluation of the anterior chamber angle to exclude angle closure or secondary causes of IOP elevation such as angle recession, pigment dispersion, peripheral anterior synechiae, angle neovascularization, and inflammatory precipitates (Tasman & Jaeger, 2009). [A:III]
Optic Nerve Head and Retinal Nerve Fiber Layer Examination
The preferred technique for optic nerve head and retinal nerve fiber layer evaluation involves magnified stereoscopic visualization (as with the slit-lamp biomicroscope), preferably through a dilated pupil. [A:III]
Fundus Examination
Examination of the fundus, through a dilated pupil whenever feasible, includes a search for other abnormalities that might account for optic nerve changes and/or visual field defects (e.g., optic nerve pallor, disc drusen, optic nerve pits, disc edema due to central nervous system disease, macular degeneration, retinal vascular occlusion, and other retinal disease). [A:III]
Supplemental Ophthalmic Testing
Central Corneal Thickness
Measurement of central corneal thickness (CCT) aids the interpretation of IOP readings and helps to stratify patient risk for optic nerve damage (Kass et al., 2002; Gordon et al., 2002; Medeiros et al., 2003; Agudelo, Molina, & Alvarez, 2002; Dueker et al., 2007). [A:II]
Visual Field Evaluation
Automated static threshold perimetry is the preferred technique for evaluating the visual field (Delgado et al., 2002). [A:III] Careful manual combined kinetic and static threshold testing (e.g., Goldmann visual fields) is an acceptable alternative when patients cannot perform automated perimetry reliably or if it is not available. [A:III] Repeat, confirmatory visual field examinations may be required for test results that are unreliable or show a new glaucomatous defect before changing management (Keltner et al., 2000; Lee et al., 2002). [A:III]
Optic Nerve Head and Retinal Nerve Fiber Layer
The appearance of the optic nerve should be documented (Lin et al., 2007; Singh et al., 2008). [A:II] Color stereophotography is an accepted method for documenting optic nerve head appearance. Computer-based image analysis of the optic nerve head and retinal nerve fiber layer is an alternative for documentation of the optic nerve and can identify patients at greater risk of progression to glaucoma (Lin et al., 2007; Zangwill et al., 2005). In the absence of these technologies, a nonstereoscopic photograph or a drawing of the optic nerve head should be recorded, but these are less desirable alternatives to stereophotography or computer-based imaging (Shaffer et al., 1975). [A:III]
Management
Goals
The goals of managing patients with POAG suspect are to achieve the following:
- Intraocular pressure controlled in the target range
- Stable optic nerve/retinal nerve fiber layer status
- Stable visual fields
Intraocular pressure is the only modifiable parameter in glaucoma and glaucoma suspect patients. The decision to begin treatment to lower IOP in the glaucoma suspect patient is complex and based on the ophthalmologist's analysis of the examination results, risk assessment, and evaluation of the patient and the patient's preferences. The number and severity of risk factors present, the prognosis, management plan, and likelihood that therapy, once started, can be long-term, should be discussed with the patient and, when feasible, with the patient's family. Risk assessment based on the Ocular Hypertension Treatment Study (OHTS) and the European Glaucoma Prevention Study may be helpful in managing the patient with glaucoma suspect.
The decision to begin treatment for a glaucoma suspect patient is particularly important, since therapy exposes patients to the risks, side effects, and expense of long-term treatment. Whether or not a patient is treated, long-term monitoring for the development of glaucoma is essential. [A:III]
The patient who is a glaucoma suspect has a chronic, asymptomatic condition that, when treated, may require frequent use of one or more medications that may cause side effects and have a substantial financial impact. When treatment is appropriate, an effective medication regimen requires attention to its effect on IOP, side effects, and the degree to which efficacy is reduced by nonadherence to therapy. The ophthalmologist should consider these issues in choosing a regimen of maximal effectiveness and tolerance to achieve the desired therapeutic response for each patient. [A:III] The diagnosis, number and severity of risk factors, prognosis and management plan, and likelihood of long-term therapy should be discussed with the patient. [A:III]
Deciding When to Treat a Patient with Glaucoma Suspect
The decision to treat a glaucoma suspect patient may arise in various settings.
- Any patient who shows evidence of optic nerve deterioration based on optic nerve head appearance, retinal nerve fiber layer loss, or visual field changes consistent with glaucomatous damage has developed POAG and should be treated as described in the Primary Open-Angle Glaucoma Preferred Practice Pattern (PPP). [A:III] (See the National Guideline Clearinghouse [NGC] summary of the American Academy of Ophthalmology [AAO] guideline, Primary Open-Angle Glaucoma.) Development of subtle abnormalities in the optic disc and retinal nerve fiber layer are best detected by comparing periodic fundus imaging with disc and retinal nerve fiber layer photography and computerized imaging of the optic nerve and nerve fiber layer.
- A new visual field defect that is consistent with a pattern of glaucomatous visual field defect, confirmed on retesting of visual fields, may indicate that the patient has developed POAG.
- A patient who demonstrates very high IOP in which optic nerve damage is likely to occur may require treatment.
- In some cases, initiating treatment to lower the risk of glaucomatous damage may be appropriate if the patient has risk factors for glaucoma, such as optic nerve appearance, that is very suspicious for glaucomatous damage, a strong family history of glaucoma, borderline visual field test findings, African American heritage, high myopia, or pseudoexfoliation (exfoliation syndrome).
Whatever the scenario, a discussion must occur between the physician and patient to outline the risks and benefits of treatment versus nontreatment.
Target Intraocular Pressure
Patients who have evidence of POAG should be treated as in the Primary Open-Angle Glaucoma PPP. (See the NGC summary of the AAO guideline, Primary Open-Angle Glaucoma.) When deciding to treat a glaucoma suspect patient, the goal of treatment is to maintain the IOP in a range at which a patient is likely to remain stable. The estimated upper limit of this range is considered the "target pressure." In glaucoma suspect patients for whom treatment has been chosen, target pressure can vary among patients, and in the same patient it may need adjustment during the clinical course. In any patient, target pressure is an estimate and a means toward the ultimate goal of protecting the patient's vision. It is reasonable to begin by choosing a target pressure 20% lower than the mean of several baseline IOP measurements. [A:I] Current IOP and its relationship to target IOP should be evaluated at each visit and individualized for each patient. [A:III]
In a patient who is a glaucoma suspect, a definite deterioration in optic nerve structure or visual field (i.e., conversion to glaucoma patient) suggests that the target pressure should be lower [A:I] and the patient should be managed as described in the Primary Open-Angle Glaucoma PPP. [A:III] (See the NGC summary of the AAO guideline, Primary Open-Angle Glaucoma.)
Therapeutic Choices
Unless contraindicated, medical therapy usually is the first intervention to lower IOP. There are many drugs available for initial therapy, and medication choice may be influenced by potential cost, side effects, and dosing schedules (see Table 1 in the original guideline document for an overview of options available). Patient adherence to therapy is enhanced by using eye drops with the fewest side effects as infrequently as necessary to achieve the target IOP. If target IOP is not achieved by one medication, then additional separate medications, combination therapies, or switching of treatments may be considered to reach the target IOP.
Prostaglandin analogs and beta-adrenergic antagonists are the most frequently used initial eye drops for lowering IOP. Prostaglandin analogs are the most effective drugs at lowering IOP and can be considered as initial medical therapy unless other considerations such as contraindications, cost, side effects, intolerance, or patient refusal preclude this. [A:I] Other agents in addition to prostaglandin analogs and beta-adrenergic antagonists include alpha2 adrenergic agonists, topical and oral carbonic anhydrase inhibitors, and parasympathomimetics. But, because prostaglandins are very safe when used once daily and they have a high IOP-lowering effect, they are usually chosen as the first therapy for a patient with glaucoma suspect.
To determine the effectiveness of the chosen therapy, it may be useful to begin by treating only one eye and then comparing the relative change of the IOP in the two eyes at follow-up visits. However, because the two eyes of an individual may not respond equally to the same medication, and because of the possibility of asymmetric spontaneous fluctuations and the potential for contralateral effect of monocular topical medications, it is acceptable to compare the effect in one eye relative to multiple baseline measurements in the same eye.
If a drug fails to reduce IOP sufficiently, then either switching to an alternative medication as monotherapy or adding additional medication is appropriate until the desired IOP level is attained. [A:III] Since some studies have shown that adding a second medication decreased adherence to glaucoma treatment, fixed combination therapy, while not recommended for initial treatment, may improve patient adherence.
The patient and the ophthalmologist together decide on a practical and feasible regimen to follow in terms of dosing, cost, and adherence in the context of the patient's age and preferences. The ophthalmologist should assess the patient for local ocular and systemic side effects and toxicity, including interactions with other medications and potential life-threatening adverse reactions. [A:III] To reduce systemic absorption after medication instillation, patients can be educated about eyelid closure or nasolacrimal occlusion (see "Patient Resources" field in this summary for availability of patient education brochures).
At each examination, medication dosage and frequency of use should be recorded. [A:III] Reviewing the time of day when medication was taken may be useful. Adherence to the therapeutic regimen and recommendations for therapeutic alternatives or diagnostic procedures should be discussed. [A:III] Patient education and informed participation in treatment decisions may improve adherence and overall effectiveness of management.
Laser trabeculoplasty may also benefit high-risk glaucoma suspect patients. If incisional surgery is to be considered, the patient can be managed as described in the Primary Open-Angle Glaucoma PPP. (See the NGC summary of the AAO guideline, Primary Open-Angle Glaucoma.) Cost may be a factor in adherence, especially when multiple medications are used.
Follow-up Evaluation
History
The following interval history should be elicited during follow-up visits for POAG suspect patients:
- Interval ocular history [A:III]
- Interval systemic medical and medication history [B:III]
- Side effects of ocular medications if the patient is being treated [A:III]
- Frequency and time of last IOP-lowering medications, and review of medication use if the patient is being treated [B:III]
Ophthalmic Examination
The following components of the ophthalmic examination should be performed during follow-up visits for POAG suspect patients:
- Visual acuity measurement [A:III]
- Slit-lamp biomicroscopy [A:III]
- Intraocular pressure measurement [A:I]
The frequency of periodic optic nerve head evaluation and documentation and visual field evaluation is based on risk assessment. Patients with thinner corneas, higher IOPs, disc hemorrhage, larger cup-to-disc, larger mean pattern standard deviation (PSD), or family history of glaucoma may warrant closer follow-up than patients with lower IOPs, normal corneal thickness, and no disc hemorrhages. Gonioscopy is indicated when there is a suspicion of an angle-closure component, anterior-chamber shallowing, anterior-chamber angle abnormalities, or if there is an unexplained change in IOP. [A:III] Gonioscopy should be performed periodically (i.e., 1 to 5 years). [A:III]
Counseling/Referral
Patients should be educated about their condition and its potential to lead to the blinding disease glaucoma, the rationale and goals of intervention, the status of their condition, and the relative benefits and risks of alternative interventions so that they can participate meaningfully in developing an appropriate plan of action. [A:III] Patients should be encouraged to alert their ophthalmologists to physical or emotional changes that occur when taking glaucoma medications, if prescribed. [A:III] The ophthalmologist should be sensitive to these problems and provide support and encouragement. [A:III]
Definitions:
Ratings of Importance to Care Process
Level A, defined as most important
Level B, defined as moderately important
Level C, defined as relevant, but not critical
Ratings of Strength of Evidence
Level I includes evidence obtained from at least one properly conducted, well-designed, randomized controlled trial. It could include meta-analyses of randomized controlled trials.
Level II includes evidence obtained from the following:
- Well-designed controlled trials without randomization
- Well-designed cohort or case-control analytic studies, preferably from more than one center
- Multiple-time series with or without the intervention
Level III includes evidence obtained from one of the following:
- Descriptive studies
- Case reports
- Reports of expert committees/organizations (e.g., Preferred Practice Pattern [PPP] panel consensus with external peer review)
