Faculty Bibliography

Objective: To determine optimal thresholds for inter-eye differences in retinal nerve fiber (RNFL) and ganglion cell+inner plexiform (GCIP) layer thicknesses that are predictive of a unilateral optic nerve lesion in multiple sclerosis (MS).
Background(s): The optic nerve is a frequent site for involvement in MS. Current international diagnostic criteria for MS do not include the optic nerve as a lesion site despite the high prevalence of acute optic neuritis (ON). Spectral-domain optical coherence tomography (SD-OCT) detects thinning of RNFL and GCIP in MS.
Method(s): In this multi-center international study at 9 sites, SD-OCT, high-contrast visual acuity (VA), low-contrast letter acuity (LCLA), and vision-specific quality of life (QOL) were measured for MS patients and healthy controls as part of the International Multiple Sclerosis Visual System Consortium (IMSVISUAL). QOL was measured using the NEI-VFQ-25 and 10-item Neuro-Ophthalmic Supplement (NOS). Presence of an optic nerve lesion was defined as history of acute unilateral ON.
Result(s): Among healthy controls (n=348), the 95th percentile value for inter-eye difference (upper boundary of expected) was 7.0 microns; for GCIP, the 95th percentile was 3.0 microns. These values were applied to the MS cohort (n=1,346), and were associated with worse vision-specific QOL for inter-eye differences above the threshold values (P<=0.04, linear regression, accounting for age). Greater inter-eye differences in VA and LCLA were associated with greater inter-eye RNFL differences (P< 0.001) and GCIP (P<=0.002). Receiver operating characteristic (ROC) curve analysis demonstrated an optimal RNFL inter-eye difference threshold of 5 microns for identifying patients with unilateral ON (n=404) in the MS cohort (point on ROC curve where sensitivity and specificity are both optimized). For GCIP, the threshold was 4 microns.
Conclusion(s): Optimal inter-eye differences of 5 microns for peripapillary RNFL and 4 microns for macular GCIP thickness are robust thresholds for identifying unilateral optic nerve lesions based on analyses of an international MS cohort

Visual symptoms, such as photophobia and blurred vision, are common in patients with concussion. Such symptoms may be accompanied by abnormalities of specific eye movements, such as saccades and convergence, or accommodation deficits. The high frequency of visual involvement in concussion is not surprising, since more than half of the brain's pathways are dedicated to vision and eye movement control. These areas include many that are most vulnerable to head trauma, including the frontal and temporal lobes. Vision and eye movement testing is important at the bedside and on the sidelines of athletic events, where brief performance measures that require eye movements, such as rapid number naming, are reliable and sensitive measures for concussion detection. Tests of vision and eye movements are also being explored clinically to identify and monitor patients with symptoms of both sport- and nonsport-related concussion. Evaluation of vision and eye movements can assist in making important decisions after concussion, including the prognosis for symptom recovery, and to direct further visual rehabilitation as necessary.