Bilateral Non-Arteritic Anterior Ischaemic Optic Neuropathy in a Patient with a COL4A2 Mutation.

Non-arteritic anterior ischaemic optic neuropathy (NAION) is a common cause of vision loss in adults and is thought to be due to compromised perfusion to the optic nerve head. Patients with NAION in one eye are at risk of recurrence in the fellow eye. We report a case of sequential, bilateral NAION in a patient who was found to have a COL4A2 mutation. COL4A2 encodes a subunit of the collagen 4 protein, the major component of the human basement membranes, and has several known cerebrovascular and ocular associations.

Approach to Diplopia.

PURPOSE OF REVIEW: "Double vision" is a commonly encountered concern in neurologic practice; the experience of diplopia is always sudden and is frequently a cause of great apprehension and potential disability for patients. Moreover, while some causes of diplopia are benign, others require immediate recognition, a focused diagnostic evaluation, and appropriate treatment to prevent vision- and life-threatening outcomes. A logical, easy-to-follow approach to the clinical evaluation of patients with diplopia is helpful in ensuring accurate localization, a comprehensive differential diagnosis, and optimal patient care. This article provides a foundation for formulating an approach to the patient with diplopia and includes practical examples of developing the differential diagnosis, effectively using confirmatory examination techniques, determining an appropriate diagnostic strategy, and (where applicable) providing effective treatment. RECENT FINDINGS: Recent population-based analyses have determined that diplopia is a common presentation in both ambulatory and emergency department settings, with 850,000 such visits occurring annually. For patients presenting to an outpatient facility, diagnoses are rarely serious. However, potentially life-threatening causes (predominantly stroke or transient ischemic attack) can be encountered. In patients presenting with diplopia related to isolated cranial nerve palsy, immediate neuroimaging can often be avoided if an appropriate history and examination are used to exclude worrisome etiologies. SUMMARY: Binocular diplopia is most often due to a neurologic cause. The onset of true "double vision" is debilitating for most patients and commonly prompts immediate access to health care services as a consequence of functional impairment and concern for worrisome underlying causes. Although patients may seek initial evaluation through the emergency department or from their primary care/ophthalmic provider, elimination of an ocular cause will not infrequently result in the patient being referred for neurologic consultation. A logical, localization-driven, and evidence-based approach is the most effective way to arrive at the correct diagnosis and provide the best outcome for the patient.

Differentiating Acute and Subacute Vertical Strabismus Using Different Head Positions During the Upright-Supine Test.

Importance: Accurate clinical differentiation between skew deviation and fourth nerve palsy (4NP) is critical in the acute and subacute settings. Objective: To determine the sensitivity and specificity of the upright-supine test to detect vertical misalignment changes using different head positions for the diagnosis of acute or subacute skew deviation vs 4NP. Design, Setting, and Participants: This multicenter study enrolled consecutive patients from Coimbra University Hospital Centre, Coimbra, Portugal, and Michigan State University, Lansing, within 2 months of presenting with vertical diplopia and diagnosed as having skew deviation or acquired unilateral 4NP. The study used nonmasked screening and diagnostic test results from June 1, 2013, to December 31, 2016. Data were analyzed from January 1, 2017, to June 30, 2017. Main Outcomes and Measures: A 50% or greater change in vertical misalignment between the upright and supine positions, with the head centered and tilted to either side. Measurements included the alternate prism and cover (APC) test, the double Maddox rod test, the APC test change index ([measurement upright - measurement supine] / [measurement upright + measurement supine]), and the APC test sensitivity and specificity. Results: Of the 37 included patients, the mean (SD) age was 58 (14) years, and 26 (70%) were male. We enrolled 19 patients (51%) with skew deviation and 18 (49%) with 4NP. Eighteen patients with skew deviation (95%) showed additional ocular motor and/or neurological signs. When moving to the supine position, only 1 patient with skew deviation (5%) showed more than a 50% decrease of hypertropia with the head centered (APC test: sensitivity, 5%; specificity, 100%). Three patients with 4NP (17%) showed more than a 50% decrease of hypertropia with the head tilted toward the hypertropic eye, and 10 patients with 4NP (56%) showed more than a 50% increase of hypertropia with the head tilted toward the hypotropic eye. Change indexes were different between the skew deviation and 4NP groups for head tilt to the hypotropic eye (difference, -0.33 prism diopters; 95% CI, -0.43 to -0.20; P < .001). Cyclotorsion worsened in the supine position only in patients with skew deviation (hypertropic eye: difference, -7.6 prism diopters; 95% CI, -13.00 to -0.75; P = .01; hypotropic eye: difference, 8.2 prism diopters; 95% CI, 0 to 15.75; P = .03). Conclusions and Relevance: The upright-supine test with the head centered is not a sensitive method to separate acute or subacute skew deviation from 4NP. Conversion of an incomitant vertical deviation in the upright position to a comitant vertical strabismus in the supine position in all head positions, as well as the absence of additional ocular motor and/or neurologic signs, may constitute a more useful clue.

Visual loss due to optic chiasm and retrochiasmal visual pathway lesions.

PURPOSE OF REVIEW: Building on the anatomic and diagnostic approaches presented elsewhere in this issue of CONTINUUM, this article presents important differential considerations for chiasmal and retrochiasmal vision loss, useful strategies for confirming the underlying etiology, principles of their natural history, and, where appropriate, treatment strategies. RECENT FINDINGS: Although a wide variety of pathologic processes can affect the optic chiasm and retrochiasmal visual pathways, those commonly seen in neurologic practice are comparatively fewer in number. This article updates current understanding of vision loss localizing to the optic chiasm, including pituitary adenoma, sellar meningiomas, and aneurysms. Important causes of retrochiasmal vision loss, including stroke and posterior reversible encephalopathy syndrome, are also presented. SUMMARY: The optic chiasm and retrochiasmal visual pathways are susceptible to various forms of injury, with resultant patterns of vision loss that can be precisely localized on the basis of clinical and neuroimaging findings. Accurate localization, in association with other clinical features, allows for consideration of relevant differential diagnoses, which can be confirmed through the judicious application of appropriate diagnostic studies. Accurate localization, diagnosis, and robust clinical surveillance are essential to the effective management and treatment of these causes of vision loss.

Nonconventional optic nerve imaging in multiple sclerosis.

Conventional MR imaging is, at present, the most important paraclinical modality for assessing the risk of MS in patients with acute demyelinating ON and for monitoring the progression of disease. However, there are limitations of conventional MR in imaging the optic nerve. Newer strategies, MT MR imaging, DT MR imaging, and OCT, show significant promise. Future investigations, including the use of nonconventional MR imaging techniques coupled with OCT and functional measures of anterior visual pathway function, will further assist in the early detection of clinical impairment. Serial analysis will allow for monitoring of disease progression, predict accumulation of disability, and ascertain the effects of candidate neuroprotective therapies.

Capturing the benefit of vision restoration therapy.

PURPOSE OF REVIEW: Vision restoration therapy has shown promise as a treatment strategy to improve visual field deficits in patients with lesions of the brain or optic nerve. Objective measures of its efficacy, however, have remained controversial. A review of the current theories supporting the reported benefits of vision restoration therapy, and the dissenting opinions, reconsiders vision restoration therapy as an emerging therapy. RECENT FINDINGS: The benefits of vision restoration therapy have been challenged by a study suggesting that no improvement exists with careful control of fixation. Alternatively, others suggest that eye movements are not induced by vision restoration therapy. Functional imaging studies demonstrate the potential role of plasticity in vision restoration therapy. While the exact mechanism remains to be elucidated, subjective improvement in daily functioning is reported in a significant percentage of patients. SUMMARY: Vision restoration therapy is a noninvasive, home-based strategy for the rehabilitation of patients with visual field loss caused by structural or ischemic damage. While subjective benefits in functional status have been reported by patients following completion of the program, debate centers around the inadequacy of the methods used to document its efficacy. Until such a method is validated by carefully controlled studies, subjective improvement in visual function stands alone as evidence of vision restoration therapy's benefit.