(2005). Pseudostrabismus: When are You Sure? American Orthoptic Journal: Vol. 55, No. 1, pp. 162-165.

The relationship between prisms and lenses can be an asset in the management of strabismus. Relief from diplopia in incomitant strabismus is challenging and may be complicated by large refractive errors or ill-fitting spectacles. Practical optical techniques include crossing and splitting incorporated prisms, using slab-off lenses or oblique prisms, and combining contact lenses with a spectacle correction or prisms. Spectacle frame selection and fit may induce an ocular deviation or influence an existing one. Selecting an appropriate frame, particularly if prisms will be incorporated, contributes to binocular comfort.

IntroductionCerebellar disease is associated with multiple abnormalities of ocular movement. The cerebellum is critical during head movements to keep the image stabilized on the retina, modulating the response to vestibular input, and matching eye movement to the required change in eye position.MethodsLiterature synopsis.ResultsRecent nonhuman primate evidence suggests a previously unrecognized role in binocular alignment. The most important cerebellar structures in eye movement control appear to be the cerebellar oculomotor vermis and its inputs to the fastigial oculomotor region. Saccadic intrusions range from common square wave jerks to potentially ominous movements like ocular flutter and opsoclonus.ConclusionIdentification of these types of eye movements of cerebellar origin will lead to appropriate evaluations.

Worth's four dot test was first described one hundred years ago. Despite many technological advances in equipment and techniques during the last century, this simple test is still used routinely by many strabismus specialists. It is an invaluable test when used in the evaluation of long-standing and acquired strabismus in adults and in the management of complex diplopia. Techniques using the test include selecting an optimal prism, assessing the effect of a prescribed prism or compensatory head posture on the range of binocular single vision, identifying non-organic responses, differentiating monocular from binocular diplopia, especially when they co-exist, and blurred from double vision in older patients with divergence paresis. It also can be used with prisms preoperatively to determine the risks of postoperative diplopia and give clues to the presence of torsion or a visual field defect.

Following facial or head trauma, a few unfortunate individuals lose the ability to fuse. With time or treatment, some regain this ability; others have permanent loss of fusion. The fusional mechanism comprises both sensory and motor components with motor fusion being synonymous with the vergence system. If the vergence mechanism is damaged, motor fusion is affected. Although it may be possible to superimpose images, they are not maintained together over a range. If sensory fusion is disrupted centrally, superimposition of images is unlikely. Central fusion loss is rare, and almost always follows a head injury. A careful history about the injury may contribute to the differential diagnosis. Convergence paralysis is the most common vergence disorder following head injury.

Background and PurposeThe outcome of surgery for esotropia in children with Down syndrome has not received significant attention.Patients and MethodsWe reviewed motor outcomes of esotropia surgery in all patients with Down syndrome in our practice from 1991–2001.ResultsTwenty-one patients had surgery for esotropia. The mean age at surgery was 55 months. The mean preoperative esotropia was 36Δ. Three patients required a second surgery: two for residual esotropia and one for consecutive exotropia. A second operation was recommended for two additional patients: one with residual esotropia and one with consecutive exotropia. The mean length of follow-up was 39 months. At the last follow-up examination, fourteen patients had a deviation of 0–10Δ(thirteen esotropic and one exotropic). Five patients had a final deviation of 11–20Δ (four esotropic and one exotropic). One patient had a residual esotropia of 21–30Δ and one had greater than 30Δ of residual esotropia.ConclusionThe motor outcomes for esotropia surgery in children with Down syndrome were not as good as those in children with acquired esotropia but were comparable to those in children with infantile esotropia. More children had residual esotropia than consecutive exotropia, which may reflect a tendency toward conservative amounts of surgery or an underlying esotropic tendency in Down syndrome. Parents of children with Down syndrome may be counseled to expect good outcomes in the surgical management of esotropia.

Diplopia following cataract extraction occurs in approximately 1% of cases or less. With over 1.5 million cataract extractions per year, this can lead to a considerable morbidity. It is typically a small vertical deviation and is distressing if unanticipated. The most common etiologies include surgical manipulation of orbital tissue from a bridle suture, extraocular muscle trauma from a retrobulbar needle or anesthetic, and unmasking an underlying strabismus or systemic condition with extraocular muscle involvement. Care must therefore be taken by obtaining a complete preoperative history and examination, document any preexisting strabismus and systemic condition, and avoid any direct extraocular muscle trauma or manipulation.

Traumatic strabismus presents the examiner with several unique challenges. The patient's signs and symptoms can vary widely from the quite dramatic to the very subtle. Symptoms may also vary from day to day. Injury sustained during head trauma can result in strabismus from neurologic causes, mechanical causes, or both. There are many questions to be answered in the motor exam of the patient with traumatic strabismus. Nerve damage can occur at any point along the pathway, peripherally or centrally. Mechanical causes include entrapment or disinsertion of the muscle from the globe. Throughout the exam, the investigator is aware that the differentiation between mechanical causes and neurologic involvement is one of the most important distinctions to make. This paper focuses on methods of identifying the key aspects and quantifying the strabismus associated with trauma.