CHAPTER 3

The Patient With Decreased Vision: Evaluation

History

In cases of decreased vision, there are 3 aspects of the history that—in addition to the age of the patient—are crucial in determining the etiology: (1) laterality of the vision loss, (2) time course of the vision loss, and (3) associated symptoms.

Unilateral Versus Bilateral Involvement

Laterality is crucial to localization: unilateral vision loss typically indicates a lesion anterior to the chiasm, whereas bilateral vision loss may reflect a bilateral ocular, chiasmal, or retrochiasmal process. Patients reporting vision loss should be asked specifically if they have checked each eye individually. Binocular involvement may not be appreciated until the patient is examined.

Time Course of Vision Loss

The speed of onset of vision loss can help determine its etiology. Sudden onset (ie, within minutes) usually indicates an ischemic event, such as arterial occlusion. Rapid vision loss developing over hours is also most often ischemic in origin. A course evolving over days to weeks more frequently denotes inflammation. Gradual progression over months is typical of toxic lesions (although such lesions may be more acute); progression over months or years is most consistent with compressive causes. Patients may become acutely aware of chronic processes when covering the uninvolved eye or only after the second eye becomes affected. Although the time course may suggest a causation of vision loss, the various etiologies exhibit considerable overlap among the different time courses.

Associated Symptoms

Globe tenderness or ipsilateral periorbital pain that increases with eye movement occurs commonly in optic neuritis. Symptoms suggestive of demyelinating disease include diplopia, oscillopsia, hemiparesis, and hemisensory changes. Nonspecific pain, facial numbness, or diplopia may indicate orbital or cavernous sinus lesions. Headache, jaw claudication, and systemic symptoms could suggest