This article has been cited by other articles in PMC. Abstract Purpose The purpose of this study was to determine the reliability of interpupillary distance IPD and pupil diameter PD measures using an infrared eye tracker and central point stimuli. Validity of the test compared to known clinical tools was determined, and normative data was established against which individuals can measure themselves. Methods Participants across various demographics were examined for normative data. Of these, 50 were examined for reliability and validity.

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Clinical Pearl: A decrease in the level of alertness occurs only if there is dysfunction of both cerebral hemispheres or the brainstem. There is no one-to-one correlation between a MSE task and a single cognitive function; mental tasks are complex and require a number of cerebral areas and cognitive functions. None of the focal deficits in the MSE has any localizing significance. There are 12 pairs of CNs. Each CN has a left and a right nerve; each side must therefore be evaluated separately.

There may be dysfunction on one side only or on both sides. Findings from each side are compared for symmetry. This chapter is organized to include details of testing, discussion of findings, and abnormal findings. See Chapter 5 for a review of the anatomy and physiology of the CNs. Olfactory Nerve Sensory CN I Testing of the olfactory nerve is often deferred unless the patient reports deficits or there is reason to believe that this function is compromised.

If indicated, the sense of smell is tested by obstructing one nostril while testing the other. Cinnamon, cloves, coffee, or peppermint are possible odors that patients should be able to identify if CN I is intact. Abnormalities Anosmia is an inability to smell. It is an early sign in the diagnosis and localization of frontal lobe tumors. There are several causes of anosmia, some of which are attributable to neuropathologic conditions such as meningiomas of the sphenoid ridge and olfactory groove, gliomas of the frontal lobe, infectious processes involving the meninges at the base of the frontal lobe, toxic substances including lead and calcium, and parasellar lesions with pressure on the olfactory bulbs or tracts.

Common non-neurological causes of anosmia include the common cold, sinusitis, or inflammation of the nasal cavity. The typical syndrome with sphenoidal ridge meningioma is one of unilateral optic atrophy or papilledema, exophthalmos, and ipsilateral anosmia.

A meningioma of the olfactory groove or cribriform plate area includes unilateral anosmia progressing to bilateral anosmia, often accompanied by unilateral ipsilateral optic atrophy, and contralateral papilledema. Testing encompasses an evaluation of visual acuity and visual fields and an ophthalmoscopic examination.

Each eye is evaluated individually while the other eye is covered. Visual Acuity Visual acuity can be evaluated informally by asking the patient to read from printed material, such as a newspaper. A standard Snellen chart is available in office or clinic settings and other settings such as the emergency department for formal testing. Each eye is checked individually.

From a distance of 20 ft 6. The number beside each line of letters signifies the number of feet at which letters can be read by a person with normal vision. This becomes the denominator in recording vision. When vision is defective, the patient may only be able to see the larger letters at 20 ft 6. An adaptation of the Snellen chart, the Rosenbaum Pocket Vision Screener, is designed for quick bedside use.

The chart is held at a distance of 14 in 0. The ratio is calculated in the same manner as for the Snellen test. Visual Fields A visual field is the area of vision normally seen with one eye. Each visual field extends 60 degrees on the nasal side, degrees on the temporal side, and degrees vertically 60 degrees superiorly and 75 degrees.

Figure displays normal visual fields. The confrontation test provides a rough estimate of the scope of each visual field.

The patient is asked to indicate when the object is first seen. The confrontation test is designed to reveal only gross defects of the visual fields. If any defects are found, the visual fields should be plotted by an ophthalmologist using the standard and more sensitive perimetric test or a tangent screen.

Visual field testing can reveal field cuts related to characteristic deficits along the visual pathway i. Chart shows specific field cuts; Figure shows field cuts in a person with right homonymous hemianopia. With bilateral occipital or occipitoparietal infarctions, there may be cortical blindness resulting in complete loss of vision often with denial or unawareness of the deficit.

Because the pupils still react to light, cortical blindness may be difficult to differentiate from hysterical blindness.

Ophthalmoscopic Examination The ophthalmoscopic examination is conducted with an ophthalmoscope, which contains a special lens that is used to visualize the retina by shining a beam of white light directly into the eye.

The room is darkened and the examiner sits directly opposite the subject. Shine the beam of light on the pupil and look for the red reflex—an orange glow reflected from the retina. Move closer toward the pupil, staying focused on the red reflex. The termination of the optic nerve, visible as a prominent, tube-like structure at the back of the eyeball and slightly to the nasal side of center, is called the optic disc. Bring the optic disc fundus into focus by adjusting the ophthalmoscope lens Fig.

The normal disc is round or slightly oval with sharply defined margins. The outer portion of the disc is elevated slightly above the center, or physiologic cup. Another area of the retina is the macula lutea, which has the highest density of visual receptors. The center of the macula, called the fovea, represents the point of greatest visual acuity. Four main pairs of blood vessels exit and enter the optic disc; they are followed peripherally in all directions to compare the diameters of the arteries and veins and to determine whether the veins are tortuous.

The presence of retinal venous pulsation indicates normal intracranial pressure; the absence may be normal or may reflect raised intracranial pressure. As the retina is examined, any abnormalities, such as hemorrhage, swelling, and exudate, should be noted. Table summarizes common ophthalmological findings. Bitemporal Hemianopia Optic Chiasm A lesion at the optic chiasm may involve only those fibers that cross over to the opposite side.

Because these fibers originate in the nasal half of each retina, visual loss involves the temporal half of each field. Left Homonymous Hemianopia Right Optic Tract A lesion of the optic tract interrupts fibers originating on the same side of both eyes. Visual loss in the eyes is therefore similar homonymous and involves half of each field hemianopia. Left Homonymous Quadrantic Defect Optic Radiation, Partial A partial lesion of the optic radiation may involve only a portion of the nerve fibers, producing, for example, a homonymous quadrantic defect.

Turn on the ophthalmoscope light and adjust the output to the small round beam of white light. Use your index finger to adjust the lens for proper focus; begin by adjusting the lens to zero diopters.

Red lens numbers indicate minus diopters turn the lens control counterclockwise and are used with a myopic nearsighted patient. Black lens numbers indicate plus diopters turn the lens control clockwise and are used for a hyperopic farsighted patient or for one who has undergone surgical lens removal. Instruct the patient to look straight ahead.

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