How to master MCQs
Chung Nen Chua, Li Wern Voon, Siddhartha Goel in Ophthalmology Fact Fixer, 2017
Duction refers to movement of one eye, whereas version refers to conjugate movement of both eyes. Because of Hering's law of equal innervation, conjugate eye movement of the affected eye is less than duction. Hess charts in both cases are reduced - however, in a neurogenic palsy, there is proportional spacing between the inner and the outer fields. Intraocular pressures are elevated in a mechanical muscle palsy when the patient looks away from the site of the mechanical lesion. Globe retraction occurs in a mechanical palsy when the patient looks away from the site of the lesion. Abnormal head posture may be adopted in both conditions.
The Problems
John Greene, Ian Bone in Understanding Neurology a problem-orientated approach, 2007
A specific diplopia examination should also be performed. Monocular occlusion is performed initially, either looking straight ahead or in whichever direction the diplopia occurs, to determine whether this does abolish the double vision. For range of motion (duction testing) the patient is asked to a) look at the target, b) follow the target with their eyes and not by moving their head, c) and to report if they see double at any point. These instructions should be clear and often need to be reiterated. The target (preferably a light to allow observation of the corneal light reflex) is held at arm’s length from the patient’s eyes. It is moved upwards, downwards, to the left, to the right, and then upwards and downwards when the patient is looking to the left and to the right. After testing with both eyes open (versions), it is useful to test each eye separately, the other being covered by the examiner’s hand (ductions). Often, duction failure (loss of movement) of the eye in a certain direction or series of directions is obvious. The common patterns of ophthalmoplegia (failure of eye movement) associated with III, IV, and VI cranial nerve palsies are demonstrated in 108. Also illustrated is the pattern seen in internuclear ophthalmoplegia; although this often does not cause diplopia, it is an important pattern to recognize, and denotes a lesion of the medial longitudinal fasciculus in the brainstem.
Maxilla: LeFort Fracture Patterns
Jeffrey R. Marcus, Detlev Erdmann, Eduardo D. Rodriguez in Essentials of CRANIOMAXILLOFACIAL TRAUMA, 2014
Blindness, although uncommon following a maxillary fracture, may occur from swelling within the optic canal. Diplopia may complicate maxillary fractures with a significant orbital component. Initially this is usually the result of extraocular muscle contusion; however, diplopia may signal muscle entrapment, and this should be determined with a forced-duction test. Persistent postoperative diplopia may indicate globe displacement or extraocular muscle dysfunction. The displaced globe may not lie at its proper level following treatment of the orbital fracture. In general, displacement must exceed 5 to 10 mm to account for diplopia.
Measurement of ductions and fields of binocular single vision (BSV): orthoptic practice in the UK and Ireland
Published in Strabismus, 2021
Catherine Jukes, A. Bjerre, C. Codina, H. Griffiths
Eye movement limitations can indicate serious pathology, such as: brain and orbital tumors,1 Graves Orbitopathy (GO),2 orbital cellulitis,3,4 orbital fractures5 chronic progressive external ophthalmoplegia,6 and multiple sclerosis.7 It is important to accurately detect and monitor limitations as these can indicate medical conditions requiring prompt investigation and treatment. Clinically, eye movement excursions are often estimated using the grading scale method; rating movements from −4 to +4.8 This method is imprecise, lacks standardization and is prone to intra and inter–observer variation.9 Clinical methods used to quantify eye movement excursions and fields of BSV are: Goldmann perimeter,10–12 Aimark perimeter,13 Arc perimeters,14 and Octopus perimeter.15 The aforementioned machines are quite large, taking up valuable clinical space. Throughout this report the term duction will be used when referring to the extent of eye movement excursions (rather than uniocular field of fixation- which refers to the measurement in six or eight positions of gaze).
Surgical Management of Ophthalmoplegia
Published in Journal of Binocular Vision and Ocular Motility, 2018
The object of operating on the contralateral eye is often described as “matching the duction deficit” in the paretic eye. However, because it cannot improve duction in the paretic eye, contralateral surgery is most effective when the duction deficit is relatively mild. In our example of right lateral rectus muscle paresis, if the right eye was unable to abduct much past midline, it would hardly be an improvement to make the patient also unable to look to the right with the left eye. Whether contralateral surgery will be of any benefit can be determined by holding the corrective prism over the sound eye. This simulates the effect of contralateral surgery and measures the secondary deviation.5 Operating on the sound eye is, in effect, correcting the secondary deviation, and that is the amount of surgery that should be planned.
Strabismus Is Correlated with Gross Motor Function in Children with Spastic Cerebral Palsy
Published in Current Eye Research, 2019
Hyeshin Jeon, Jae Ho Jung, Jin A Yoon, Heeyoung Choi
Refractive error was determined by cycloplegic refraction (3 drops 1% cyclopentolate hydrocholoride, retinoscopy after 30 minutes from the initial drop) and recorded as spherical equivalent (SE) values. High astigmatism (Dcyl≤3.0 Diopters,D), high hyperopia (SE≥5.0 D) and high myopia (SE≤-6.0 D) were defined as significant refractive error. Visual acuity was measured using Snellen chart or forced-choice preferential looking test. The visual acuity of the right eye was adopted in the analysis and the cases whose visual acuity of two eyes differ by more than 2 lines were examined. Slit lamp and fundus examination were performed. The prism and alternate cover tests were applied fixating on 30 cm and 6 m targets. The Krimsky test was used in un-cooperative patients. Duction and version were also assessed. Strabismus was classified in terms of direction (exotropia, esotropia or vertical deviation), constancy (intermittent or constant), and deviation angle (≥ 30 or <30).
Related Knowledge Centers
- Eye
- Eye Movement
- Vergence
- Extraocular Muscles
- Eye Examination