The case history remains one of the last strongholds of the clinician, besieged by dire predictions of its imminent replacement by continually refined neurologic imaging techniques. These computer-based procedures, and the thoroughness of the neuro-ophthalmologic examination, must raise doubts regarding the usefulness of the labor-intensive (supposedly anachronistic) elicitation of the detailed account of each patient’s illness. Holmes,¹ one of the great students of the eye and nervous system, succinctly rebutted similar doubts by affirming that “the final diagnosis is often as dependent on an accurate history as on a clinical examination.”

Holmes had a twofold approach to the medical history. First, he included a description of the illness in the patient’s words, uninfluenced by the physician’s leading questions. Second, the chronology or any ambiguous terminology was clarified by “a definite system of investigation… to determine: (a) the exact nature of each symptom; (b) its relations in space; (c) its relations in time; and (d) the factors which influence it.”¹

Ideally, the history begins a process of diagnosis and directs the clinician to focus the examination on structures most likely to have caused particular neuro-ophthalmologic complaints. In addition to suggesting a tentative topographic localization, the patient’s recollection of onset, progression, and recurrence of symptoms also may hint at etiology. Specific clinical paradigms (e.g., the sudden onset of visual loss stemming from optic nerve ischemia or inflammation, the fluctuating diplopia of myasthenia, or the indolent visual decline of tumoral compression of the anterior visual pathways) are invaluable leads to precise diagnosis. Circumstantial aspects of visual dysfunction, such as an inability to adapt visually in a darkened theater (pigmentary retinopathy), blurred vision during a hot bath (demyelinating optic neuropathy), or image degradation in bright light (posterior subcapsular cataracts), provide important etiologic clues.

The past medical background often sheds light on the acute complaint. In a patient with a prior history of diabetes or thyroid disease, the evaluation of acquired diplopia may be streamlined. Similarly, neuroradiologic studies are superfluous when slit-lamp detection of posterior subcapsular cataracts or ophthalmoscopic observation of pigmentary macular retinopathy confirms the cause of visual loss in the setting of chronic corticosteroid or thioridazine use, respectively. The details of personal and nutritional habits may prove critical: a puzzling progression of bilateral central visual loss is recognized as nutritional “amblyopia” with the revelation of excessive alcohol intake and an especially poor diet; an immunodeficient basis of cytomegalovirus retinopathy may be brought forward in the self-confessed intravenous drug abuser or homosexual.

The transition from appropriate inquiries to diagnostic precision is most readily conveyed by specific instances of history taking. In this chapter, the diagnostic choices prompted by frequently encountered historical paradigms and the symptom complexes of visual sensory or ocular motility disturbances, or of ocular/cephalic pain, are examined.

As described by Traquair,² the field of vision is “a portion of an immense hollow sphere upon the inner surface of which is spread a panoramic picture of external objects showing the central feature depicted with minute detail and vivid colouring, while objects at increasing distance from the centre are indicated with correspondingly diminished clearness and duller hues.” These external objects are not merely projected onto a static retina. James ³ likened peripheral areas to “sentinels, which when beams of light move over them, cry ‘Who goes there?’ and call the fovea to the spot.” The clinician must know that the dynamic process of normal vision is heir to transient and benign vagaries of function, such as fleeting constriction and dimming of the visual field periphery with relative retinal hypoperfusion induced by rapid postural changes. Some phenomena, such as suppression of vision ⁴ and visual masking during saccades, occur constantly and do not intrude on the observer’s awareness. The extraretinal mechanism subserving saccadic suppression operates very early in the visual pathway, within the thalamus or possibly the primary visual cortex.⁵ Not only is vision suppressed during a saccade but many of the details of the view preceding the saccade are lost. This change-blindness also occurs with other brief visual disruptions, such as blinks, mud splashes on a windshield, or a camera cut in a film sequence.⁶ Other benign vision obscurations may be caused by the following:

Stimuli as diverse as a flashbulb ignition or a video display terminal can affect vision with afterimages of retinal⁷ or cerebral⁸ origin.

Intermittent darkening of the visual field (blank-out) can occur in patients undergoing bowl-type perimetry and is attributed to the effects of full-field illumination (Ganzfeld).⁹ Momentary loss of vision or “snowstorm” in the intact eye of patients wearing an eye patch may result from binocular rivalry suppression.¹⁰ Visual interference can occur as a result of images (entoptic phenomena) caused by the inherent structure of the eye. Bright lights may be encircled by entoptic halos that are produced by a normal lens and cornea but have a smaller diameter than the pathologic halo of glaucomatous corneal edema.¹¹ When one observes a uniformly illuminated background, such as the sky, vitreous floaters consisting of a condensation of collagen fibrils are more readily perceived. The insidious or abrupt appearance of these muscae volitantes¹² or the ringlike opacity of posterior vitreous peripapillary detachment usually is a benign concomitant of aging, although the sudden onset of many floaters and phosphenes may signify intravitreal hemorrhage or retinal detachment. Pinpoint luminosities, darting more rapidly than the gentle drift of vitreous floaters, probably represent cells moving within the retinal capillary circulation.

Phosphenes are luminous sensations that may be perceived spontaneously on eye closure, especially in children,¹³ or by astronauts exposed to high-energy, heavy cosmic particles.¹⁴ They also are caused by mechanical distortion of the retina induced by pressure on the globe, accommodation, rapid (saccadic) eye movement, or forward separation of the vitreous from the retinal surface. The latter phenomenon triggers the entoptic “lightning streaks” described by Moore,¹⁵ who emphasized their benign prognosis. These symptoms of posterior vitreous detachment¹⁶ alarm the patient and may prove difficult to distinguish from similar symptoms of less benign origin.

Pathologic disturbances of vision may be transient or permanent, simple or complex, and negative or positive. Patients detect a startling positive complex visual obscuration, such as a scintillating scotoma, more readily than a simple negative peripheral field defect. The ability to ignore small scotomata, or even more extensive visual depressions, is exemplified by the subjective imperception of the physiologic blind spot or of angioscotomata during monocular viewing conditions. Similarly, Helmholtz¹⁷ remarked on the deep inattention to visual defects occasionally encountered in “cases where one eye has gradually gone blind, and the patient lived for an indefinite time without knowing it, until through accidental closure of the healthy eye alone, the blindness of the other was brought to attention.” Nonawareness of homonymous hemianopsia may aid in cerebral localization, because such neglect may signify a large parietal lesion or lesions interrupting the associative pathways to the primary or secondary visual cortices. Partial or full awareness of hemianopia is more typical of purely occipital lesions.¹⁸ Alternatively, patients may attribute visual loss to one eye when in reality an ipsilateral hemianopia is present.

Transient pathologic visual loss can occur from events at any level of the afferent visual system, from the cornea to the occipital poles.¹⁹ The following lists give examples of these events.