The patient's eyes are observed for possible misalignment, and the patient is asked for diplopia. Horizontal misalignment is described in terms of exodeviation exotropia and exophoria indicating an outward deviation of the nonfixing eye and esodeviation esotropia and esophoria indicating an inward deviation of the nonfixing eye. In general, a tropia is a manifest ocular misalignment, and a phoria is a latent one which manifests after interruption of fusion.
Thus, in hypotropia the nonfixing eye is lower. In most neurological disease, a strabismus is nonconcomitant. After testing the ocular movements in the nine directions, the next step is to test the capacity to stabilize the gaze.
The patient is requested to look ahead, to look near and far and then excentric for at least 2 min to detect gaze-evoked nystagmus. By using an ophthalmoscope, the Frenzel glasses or the Munich Fresnel glasses fixation is suppressed, and spontaneous nystagmus due to a vestibular disorder can be detected. By keeping some rules in mind and recognizing common patterns of ophthalmoparesis, the most frequent disturbances of ocular misalignment can be evaluated clinically at the bedside. The four rules to identify a weak extraocular muscle are as follows: I the false image is usually the less sharp and the more peripheral one, II diplopia occurs in positions which depend on the contraction of the affected muscle, III the false image is projected into the usual direction of the affected muscle, and IV the distance between the two images increases in the direction of action of the affected muscle.
A diagram for a differential diagnosis of diplopia concerning acute neurogenic, myogenic orbital , and central processes is presented in Figure 4. Diagram to analyze acute diplopia[ 51 ]. This pattern is usually easy to recognize. The separated images are horizontally side by side, and the distance increases in the direction of action of the lateral rectus muscle. A diminished abduction can be observed. The patient complains about double vision when looking into distance e. Sometimes, double vision is avoided by a head tilt to the affected side avoiding abduction the paretic eye.
Thus, during examination, a proper head position has to be maintained. It should always be kept in mind, that the etiology of an impaired lateral rectus muscle can be neurogenic, mechanical, myogenic, or neuromuscular. In full oculomotor nerve palsy, the parasympathetic function and the levator function are impaired, thus a pronounced ptosis is present and the pupil is wide and without reaction. Thus, mainly adduction, elevation, and depression in abduction are impaired. This condition is most difficult to identify. The double vision is most prominent looking down going downstairs or during reading near viewing.
The images are twisted with one image at an angle to the other image or rarely vertical. Looking to the opposite side of the affected nerve and tilting, the head ipsilateral to the affected site hyperdeviation is more prominent and increasing.
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This can be elicited by the Bielschowsky head tilt test. A squint is usually not visible. Saccades represent rapid, targeted eye movements. The clinician observes the saccades whether they are possible at all, too slow, hypometric, and hypermetric or accurate. This test is followed by the test of vertical saccades in a similar way.
In addition, the cerebellum has a modulating effect. Therefore, in a cerebellar disorder, often a saccadic smooth pursuit is encountered. For clinical testing of saccadic function, the King-Devick-test can be applied [test card, Figure 2 ]. In this test, the examined person has to read loudly the numbers of a demonstration card from left to right and from above to below.
Then, the person has to read three standardized test cards.
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The results of required time and of mistakes are noted. By this method, the capacity to generate saccades is tested whereby alertness, speech function, and additional neurocognitive functions contribute to the competency. In patients with traumatic brain injury, Parkinson's disease or multiple sclerosis, in whom often neuro-ophthalmologic complaints occur, this test reveals significant impairments.
In testing the smooth pursuit, the patient is asked to fix an object stethoscope, reflex hammer, or finger of the examiner which is moved smoothly horizontally and vertically. In particular, the projections from the temporo-parieto-occipital cortex and the frontal eye fields to the pons are essential as well as the function of the abducens nerve. Testing convergence is best done by requesting the patient to look down to his outstretched thumb which is slowly moved to the nose. It is judged whether this is possible without problems or at which distance the fusion is insufficient, and exotropia occurs.
Physiologically, the constriction of the pupil should be recognized whereby the neuronal mechanism of this pathway is not fully understood. The normal near point of convergence is between 5 and 10 cm. Disorders of convergence are frequently encountered in patients with traumatic brain injuries. This pattern of eye movement disorder is caused by a dysfunction of the MLF, a connection between the oculomotor nuclei.
Often the disorder is accompanied by a nystagmus on the abduction of the contralateral eye. The vestibulo-ocular reflex connects the vestibular system with the ocular system. Following a rapid head impulse, the position of the eyes is held physiologically stable. To detect a peripheral vestibular disorder, the head impulse test is quite useful. The test, introduced by Halmagyi was described recently in a review in this journal.
Slowly developing visual field defects are typically not noted by the patient, at least not before disturbances in daily life occur such as getting stuck in a door frame, causing a traffic accident or problems with reading. In diseases with shorter duration, the disturbances may be described as a type of fog or dark spots.
To test the visual fields clinically at the bedside, the confrontation test is used. The examiner stands at a distance of about 1 m to the patient with the eyes at the same height as the patient. The patient is asked to look with both eyes at the nose of the examiner while the latter one is stretching the arms and hands at first into both upper quadrants and then into both lower quadrants. The examiner looks into the eyes of the patient and simultaneously moves one or both index fingers asking the patient which finger moves. This examination is of course only a very rough one. A visual field defect can be analyzed in more detail at the bedside by examining each eye separately.
This method can be supplemented by using red points such as the cap of a red biro.
A unilateral loss of such a reaction is a strong hint for hemianopia. With these clinical tests usually a homonymous hemianopia or quadrantanopia and a bitemporal hemianopia should be recognized. Bitemporal visual field deficits indicate a dysfunction of the optic chiasm, for example, due to a pituitary adenoma. Homonymous hemianopia or quadrantanopia indicates a dysfunction of the postchiasmal optic pathway and the visual cortex. A lower quadrantanopia is the result of a lesion at the upper retrochiasmatic visual pathway Baum's loop in the parietal cortex.leondumoulin.nl/language/lab/leslies-secret-a.php
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For exact analysis of the visual fields perimetry in the hands of the ophthalmologist is necessary. This method enables additional detection of circumscribed visual deficits and enlargement of the blind spot. Applying fundoscopy the ocular fundus and in particular the papilla can be inspected even without pharmacological mydriasis. The doctor's eye usually examines the same eye of the patient, i. In the dimmed room, the patient is asked to look slightly upward and inward.
The examiner nears slowly with the ophthalmoscope and sees through the pupil the ocular fundus, first catching vessels, and then following them to the papilla.
By nearing from the temporal side, the constriction of the pupil is normally less intensive. For the neurologist in the emergency situation, the recognition of optic disc swelling and its differential diagnoses as well as optic atrophy should be possible. Patient year-old, headache during soccer play, slight diplopia. Courtesy of Dr. Higher visual disturbances can be caused by functional and structural disorders of the visual cortex and its associative structures. These higher visual disorders are frequently associated by additional neurologic symptoms and signs.
This topic is described elsewhere in detail. It is important for the physician to be ready to pay attention to such phenomena of the patient and to ask the patient in more detail when such disorders are assumed. The experience of visual hallucinations in visually impaired individuals, namely Charles Bonnet syndrome, not only occurs in the elderly but also among young subjects.
Each eye is tested separately, in presbyopic patients with adequate spectacle correction. The test card shows a grid with a central fixation mark; the patient is asked whether he sees dark or blurred spots, curved lines, gaps or whether he is able to see the central dot.