Applied Evidence

A differential guide to 5 eye complaints

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Here’s help identifying conditions you can’t afford to miss, including a handy mnemonic to ensure a comprehensive eye exam.



Practice recommendations
  • Provide an urgent ophthalmology referral for any patient with a sudden decrease in visual acuity. C
  • Record bilateral pupil size as part of a comprehensive eye exam, and provide an urgent referral for a patient whose pupils are of unequal size. C
  • Involve an ophthalmologist or other specialist in the management of eye conditions caused by systemic diseases such as stroke or giant cell arteritis. C

Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

Knowing how to respond when patients present with problems involving the eye is crucial for family physicians. Yet it is often difficult to know whether to treat or refer and which signs and symptoms are indicative of an ophthalmologic emergency with the potential to cause loss of sight.

Categorizing ophthalmologic conditions based on patients’ chief complaints, we have found, can help to narrow the differential diagnosis and home in on emergent signs and symptoms. Thus, we’ve used that approach in this review.

In the pages that follow, common complaints like “I can’t see,” “I’m seeing things,” and “My eye hurts” are used to highlight disorders—both benign and emergent—associated with each. You’ll also find an at-a-glance table listing the differential diagnosis for each presentation, and a mnemonic to guide you through the elements of a comprehensive eye exam.

1) "I can't see"

Patients may use words like “cloudy vision,“ “a veil over my eyes,” or “fuzziness” to describe diminished vision. Some will report black areas within their visual field; others will have a loss of peripheral vision or total vision loss in one eye, or possibly even both. Some causes of vision problems, such as cataracts, are not emergencies. Causes of more severe (but painless) vision loss include central retinal artery occlusion (CRAO) or vein occlusion (CRVO), giant cell arteritis (GCA), stroke or transient ischemic attack (TIA), nonarteritic anterior ischemic optic neuropathy (NAION), and nonorganic (functional) vision loss (TABLE).1-11

When the cause is ischemic
Patients with CRAO experience acute loss of vision in one eye, usually occurring within seconds to minutes. Most patients with CRVO will have a similar presentation, depending on the presence or absence of ischemia and involvement of the macula. Those with branch retinal vein occlusion may have no vision loss
at all.1-3

Risk factors for CRAO include cardiovascular disease, hypertension, diabetes, and other disorders associated with systemic inflammation. In patients older than 60 years, it is also important to consider GCA, which we’ll talk more about shortly, as a cause of CRAO.

In patients with CRAO, an eye exam will show profoundly decreased visual acuity, and the swinging light test (see “Use this mnemonic to ensure a comprehensive eye exam” on page 348) will reveal a relative afferent pupillary defect (RAPD). Fundoscopy is diagnostic, revealing a pale retina due to decreased blood flow.4 Emergent referral to ophthalmology is indicated to establish a definitive diagnosis and initiate treatment based on the cause of the occlusion. If emergency care is not immediately available, massaging the eye globe through closed lids, then releasing, in 10- to 15-second cycles, may be helpful.5

Use this mnemonic to ensure a comprehensive eye exam. In a potential emergency, an eye exam needs to be quick and thorough. To ensure that all the key elements are included, use the mnemonic VVEEPP (Visual acuity, Visual fields, External exam, Extraocular movements, Pupillary exam, and Pressure) as a guide.1

Visual acuity. Check distance vision, with the patient wearing his or her corrective lenses, if possible. If not, substitute pinhole testing, which can function like corrective lenses and eliminate refractive error.2

Begin with distance charts. If the patient can’t see the charts, hold up fingers and ask whether the patient is able to count them. If not, try hand motion—or, if the patient can’t see that, try testing the patient’s ability to see light. Swing a light between the eyes. Paradoxical dilation of the affected eye when directly exposed to the light is evidence of a relative afferent pupillary defect (RAPD).2

Visual fields. Examine visual fields by using the standard confrontation technique—ie, asking the patient to cover one eye at a time while you move your hand in and out of his or her visual field.

External exam and extraocular movements. Use a penlight to inspect the eyelids, conjunctiva, sclera, cornea, and anterior chamber of the eye and to assess extraocular movements.1

Pupillary examination and pressure. Observe bilateral pupil size and swing a light between the eyes to test pupillary response to direct and consensual light (and to rule out an RAPD).2 If available, measure eye pressure, as well.1

Fundoscopy should be performed to complete the examination—along with a slit lamp evaluation, if possible.1


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