Faculty Bibliography

Multiple sclerosis (MS) is the quintessential neurologic disorder from which to understand the principles of afferent and efferent neuro-ophthalmology. Perhaps with the exception of stroke, no other disorder is associated with nearly every sign and symptom of abnormalities targeting the visual system and the ocular motor apparatus. This focused review will underscore the most common syndromes and their derivative signs and symptoms that affect vision as a consequence of MS.

Optical coherence tomography (OCT) is a non-invasive method to quantify neurodegeneration as an outcome in multiple sclerosis clinical trials; however, no data exist on Cirrus spectral domain optical coherence tomography (SD-OCT) reproducibility in patients with multiple sclerosis. The objective of this study was to determine the protocol for achieving optimal inter-visit, inter-rater, and intra-rater reproducibility for studies performed on healthy controls and multiple sclerosis patients utilizing novel high-definition SD-OCT. This is a prospective study of inter-visit, inter-rater, and intra-rater reproducibility in multiple sclerosis patients (n = 58) and healthy controls (n = 32) on Cirrus-HD SD-OCT. Excellent reproducibility of average and quadrantic retinal nerve fiber layer (RNFL) thickness values, average macular thickness (AMT), and total macular volume (TMV) [measured by intraclass correlation coefficient (ICC)] was found for inter-visit (healthy controls: mean RNFL = 0.97, quadrant range = 0.92-0.97, AMT = 0.97, TMV = 0.92), inter-rater (MS: mean RNFL = 0.97, quadrant = 0.94-0.98, AMT = 0.99, TMV = 0.96; healthy controls: mean RNFL = 0.97, quadrant = 0.94-0.97, AMT = 0.98, TMV = 0.99), and intra-rater (MS patients: mean RNFL = 0.99, quadrant = 0.83-0.99, AMT = 0.97, TMV = 0.98) reproducibility. The reproducibility of retinal measures derived by Cirrus HD-OCT, especially quadrantic values, is excellent. Specific procedures for OCT acquisition and analysis of retinal imaging metrics using SD-OCT technology may improve the application of this novel technology in multiple sclerosis.

OBJECTIVE: Cross-sectional studies of optical coherence tomography (OCT) show that retinal nerve fiber layer (RNFL) thickness is reduced in multiple sclerosis (MS) and correlates with visual function. We determined how longitudinal changes in RNFL thickness relate to visual loss. We also examined patterns of RNFL thinning over time in MS eyes with and without a prior history of acute optic neuritis (ON). METHODS: Patients underwent OCT measurement of RNFL thickness at baseline and at 6-month intervals during a mean follow-up of 18 months at 3 centers. Low-contrast letter acuity (2.5%, 1.25% contrast) and visual acuity (VA) were assessed. RESULTS: Among 299 patients (593 eyes) with >or=6 months follow-up, eyes with visual loss showed greater RNFL thinning compared to eyes with stable vision (low-contrast acuity, 2.5%: p < 0.001; VA: p = 0.005). RNFL thinning increased over time, with average losses of 2.9microm at 2 to 3 years and 6.1microm at 3 to 4.5 years (p < 0.001 vs 0.5-1-year follow-up interval). These patterns were observed for eyes with or without prior history of ON. Proportions of eyes with RNFL loss greater than test-retest variability (>or=6.6microm) increased from 11% at 0 to 1 year to 44% at 3 to 4.5 years (p < 0.001). INTERPRETATION: Progressive RNFL thinning occurs as a function of time in some patients with MS, even in the absence of ON, and is associated with clinically significant visual loss. These findings are consistent with subclinical axonal loss in the anterior visual pathway in MS, and support the use of OCT and low-contrast acuity as methods to evaluate the effectiveness of putative neuroprotection protocols.

We report two patients, both with a history of gastric surgery, who presented with progressive optic neuropathy and myelopathy. The patients' symptoms were initially attributed to vitamin B12 deficiency and/or neuromyelitis optica; however, after the neurologic deficits continued to progress with the use of conventional treatments, further evaluation was initiated, and a severe copper deficiency was revealed. Copper deficiency is a rare cause of progressive optic neuropathy and myelopathy and should be considered in the differential diagnosis. It is crucial to elicit a history of gastric surgery or other risk factors for hypocupremia in those patients undergoing an evaluation for subacute or chronically progressive optic neuropathy or myelopathy.

BACKGROUND: Disturbances in visual function are common in patients with multiple sclerosis (MS) and are often accompanied by substantial impairments in daily functioning and quality of life. Lesions associated with these impairments frequently involve the afferent visual pathway. EXPERT CLINICAL OPINION: Because these impairments are often not readily apparent on commonly used high-contrast acuity tests, low-contrast charts (e.g., low-contrast Sloan letter charts) have gained validity in the assessment of visual dysfunction in patients with MS. Decrements in low-contrast letter acuity are associated with MS and correlate with increasing disability, MRI abnormalities, and reduced retinal nerve fiber layer (RNFL) thickness as measured by optical coherence tomography (OCT). These findings suggest that low-contrast letter acuity testing is a potentially useful addition to disability scales such as the Multiple Sclerosis Functional Composite, serving as another surrogate marker for MS disability. Assessment of RNFL thickness by OCT, which is also associated with visual impairment, also may be considered for inclusion in clinical trials evaluating treatments for MS. FUTURE DIRECTIONS: The effects of disease-modifying therapies on visual dysfunction in patients with MS have been evaluated only recently. Two phase 3 studies of natalizumab showed that low-contrast letter acuity testing, included as an exploratory outcome, demonstrated treatment effects. Other ongoing studies have incorporated low-contrast acuity and OCT measures of RNFL thickness. The availability and wider use of low-contrast letter acuity tests, in combination with ocular imaging techniques, may improve assessment of treatment efficacy in patients with MS.

Friedreich ataxia is an autosomal recessive neurodegenerative disorder characterized by ataxia of all four limbs, dysarthria, and arreflexia. A variety of measures are currently used to quantify disease progression, including the Friedreich Ataxia Rating Scale, examiner-rated functional disability scales, self-reported activities of daily living and performance measures such as the timed 25-foot walk, 9-hole pegboard test, PATA speech test, and low-contrast letter acuity vision charts. This study examines the rate of disease progression over one and two years in a cohort of 236 Friedreich ataxia patients using these scales and performance measure composites. The Friedreich Ataxia Rating Scale and performance-measure composites captured disease progression, with a greater sensitivity to change over 2 years than over 1 year. The measures differed in their sensitivity to change and in possible bias. These results help to establish norms for progression in FRDA that can be useful in measuring the long-term success of therapeutic agents and defining sample-size calculations for double-blind clinical trials.

BACKGROUND: Patient nonattendance in neurology and other subspecialty clinics is closely linked to longer waiting times for appointments. We developed a new scheduling system for residents' clinic that reduced average waiting times from >4 months to < or =3 weeks. The purpose of this study was to compare nonattendance for clinics scheduled using the new model (termed "rapid access") vs those scheduled using the traditional system. METHODS: In the rapid access system, nonestablished (new) patients are scheduled on a first-come, first-served basis for appointments that must occur within 2 weeks of their telephone request. Nonattendance for new patient appointments (cancellations plus no-shows) was compared for patients scheduled under the traditional vs the rapid access scheduling systems. Nonattendance was compared for periods of 6, 12, and 18 months following change in scheduling system using the chi2 test and logistic regression. RESULTS: Compared to the traditional scheduling system, the rapid access system was associated with a 50% reduction in nonattendance over 18 months (64% [812/1,261 scheduled visits] vs 31% [326/1,059 scheduled visits], p < 0.0001). In logistic regression models, appointment waiting time was a major factor in the relation between rapid access scheduling and nonattendance. Demographics, diagnoses, and likelihood of scheduling follow-up visits were similar between the 2 systems. CONCLUSIONS: A new scheduling system that minimizes waiting times for new patient appointments has been effective in substantially reducing nonattendance in our neurology residents' clinic. This rapid access system should be considered for implementation and will likely enhance the outpatient educational experience for trainees in neurology.

Visual loss is a common symptom brought to the attention of the practicing neurologist. In this circumstance, the proper identification of an optic neuropathy is critical. Recognition of key clinical clues will permit the clinician to construct a likely differential diagnosis and pursue appropriate testing. This review first addresses the elements of the history and examination which are most useful in evaluating a patient with visual loss, and then briefly discusses the main entities responsible for causing unilateral and bilateral optic neuropathies.