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The nervous system
Published in Peter Kopelman, Dame Jane Dacre, Handbook of Clinical Skills, 2019
Peter Kopelman, Dame Jane Dacre
Strabismus This is an abnormality of ocular movement such that the visual axes do not meet at the point of fixation (Fig. 6.40). Paralytic strabismus is due to weakness of one or more of the extraocular muscles. The following clinical features are seen in paralytic strabismus: Limitation of movement: a prominent feature is impairment of ocular movement in the direction of action of the muscles affected.False orientation of the field of vision: there is erroneous judgement by the patient of the position of the object in that portion of the field of vision towards which the paralysed muscles should usually move the eye. Patients point wide of an object if they close the unaffected eye.Diplopia: patients with paralytic strabismus complain of double vision.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Several authors of recent textbooks in clinical neuroscience distinguish between paralytic and nonparalytic strabismus. Though there are often differences in the findings associated with paralytic vs. nonparalytic strabismus (e.g., DeJ, p. 142), the two categories are clearly not so much descriptive as they are pathogenetic or causative. Paralytic strabismus is generally ascribed to lesions in individual ocular nerves (III, IV, VI) or extraocular muscles; whereas nonparalytic strabismus is generally ascribed to some other factor (e.g., DeJ, p. 142, A&V, p. 200). Thornas and Dale, however, define the terms quite differently. They consider “paralytic strabismus” as synonymous with manifest strabismus or “tropia,” and “nonparalytic strabismus” as synonymous with latent strabismus or “phoria” (1981, p. 92–93).
Normal and Abnormal Development of the Neuronal Response Properties in Primate Visual Cortex
Published in Jon H. Kaas, Christine E. Collins, The Primate Visual System, 2003
Yuzo M. Chino, Hua Bi, Bin Zhang
In monkey models of binocular vision anomalies, strabismus is simulated by surgical or optical methods that are applied shortly after birth. The nature of early abnormal visual experience and the consequences of these two rearing methods can be substantially different. In the surgical method,125 the extraocular muscles of one eye are sectioned or tied to induce misalignment, thereby simulating a paralytic type of strabismus in humans, which is less common in humans than comitant strabismus (i.e., the angle of deviation does not change with gaze). In animals with noncomitant paralytic strabismus, the treated eye is immediately placed at a competitive disadvantage and the untreated eye is most likely to become the “fixating” eye. Eventually, the treated eye is likely to develop amblyopia due to uncontrolled defocus in that eye (e.g., References 81, 84, and 104).
Clinical Characteristics of Acquired Diplopia in Adults
Published in Journal of Binocular Vision and Ocular Motility, 2022
The most common etiologies of symptomatic strabismus seen in this study are summarized in Table 2. Paralytic strabismus occurred in 48 patients (21%); trochlear nerve paresis in 24 patients (11%), abducens nerve paresis in 18 patients (8%), and ocular motor paresis in 6 patients (3%). One patient had both CN 3 and CN4 palsies. Twenty-three patients (10%) were found to have diplopia associated with benign, age-related divergence insufficiency-type esotropia. Restrictive strabismus was seen in 20 patients (9%), convergence insufficiency-type exotropia in 16 patients (7%), and dragged fovea-diplopia syndrome was responsible for diplopia in 7 patients (3%). In the dragged fovea-diplopia group, 6 of the 7 cases were associated with epiretinal membrane (ERM) and could not fuse in the clinic with prism offset in free space. The lights on/off test, described by De Pool and coworkers in 2005,3 was used to make the clinical diagnosis.
A 2020 Update on 20/20 X 2 Diplopia after Ocular Surgery: Strabismus Following Retinal Detachment Surgery
Published in Journal of Binocular Vision and Ocular Motility, 2021
Prisms/cover test examination at near and primary and secondary distance gazesOcular torsionSensory evaluation including suppression, fusion, and stereopsisOcular rotations including ductions and versionsDiplopia testing with prism in free spaceGuyton lights light on/off test (dragged fovea diplopia)24Synoptophore examination for those with unstable fusion, significant torsion, aniseikonia, macular distortion, and inability to fuse on the free space prisms testHolmes optotype-frame test (retinal misregistration)25Orbital imaging is reserved for patients with progressive strabismus or late-onset strabismus or patients with other conditions that can affect the surgical approach and prognosis, for example, myopic strabismus, trauma, acquired paralytic strabismus22
The Management of Childhood Intracranial Tumours and the Role of the Ophthalmologist
Published in Neuro-Ophthalmology, 2019
G. Mole, R. Edminson, A Higham, C. Hopper, D. Hildebrand
Our study has all the limitations of retrospective reviews: namely reliance on existing case records and absence of standardization of initial assessment at presentation. Many of the children did not have a formal orthoptic review until after their initial decompression surgery. Therefore, it is difficult to conclude at exactly what point children developed strabismus. Although we report 33 patients had non-paralytic strabismus during follow up, we suspect that many of these patients had resolved paralytic strabismus which has been previously reported.34 There was only one case in which a child presented with non-paralytic strabismus which was an exotropia in the context of very reduced vision in one eye. One child also had a longstanding esotropia that had previously been operated on and so was incidental.