Should Optical Coherence Tomography Be Used to Manage Patients With Multiple Sclerosis?

Abstract

Over the past decade, optical coherence tomography (OCT) has become widely used in neuro-ophthalmology, mostly to assess the thickness of the peripapillary retinal nerve fiber layer (RNFL) and macular volume (1,2). OCT allows for objective and quantitative assessment of structural damage in the visual pathways, with a multitude of clinical and research applications. Thinning of RNFL and loss of macular volume have been found in multiple sclerosis (MS) patients, both with and without distinct episodes of optic neuritis (ON) suggesting ongoing loss of axons and neurons within the anterior visual system (1-3). There is strong evidence that accrual of neurologic dysfunction in MS correlates best with axonal and neuronal loss (rather than demyelination), but the magnetic resonance imaging (MRI) techniques available to measure such loss are cumbersome, expensive, and time consuming. OCT has emerged as a noninvasive and relatively inexpensive technique for capturing what we infer to be loss of central nervous system (CNS) axons and neurons.Whether OCT should be used mostly as an outcome measure in clinical trials or routinely to evaluate and follow patients with optic neuropathies, particularly those with ON and demyelinating disease, remains debated, as illustrated by the case below.A 31-year-old Caucasian woman was evaluated in the neuro-ophthalmology clinic for subacute painful visual loss in the right eye. Her examination was consistent with an isolated right retrobulbar optic neuropathy. She was diagnosed with right optic neuritis, likely secondary to demyelinating disease. She reported episodes of tingling over her left arm, and her brain MRI demonstrated multiple white matter lesions, some of which enhance. The diagnosis of clinically definite MS was made. She received intravenous methylprednisolone and was started on immunomodulating treatment for MS. Her visual function recovered over a few weeks, and she developed mild right optic nerve pallor. The treating neurologist requests a baseline OCT of the peripapillary RNFL. PRO-OCT Should Be Obtained in This Patient: Fiona Costello, MD, FRCPIn my opinion, a baseline OCT should be obtained to better understand what the diagnoses of ON and MS may mean for this patient.In the case provided, the patient has experienced a clinical episode of ON in the right eye, whereas the left eye is presumed to be normal. Previous OCT studies have demonstrated that RNFL measurements and macular volumes are lower in both the ON eyes and presumed unaffected eyes of MS patients relative to healthy controls ( Fig. 1) (3-6). A recent systematic review and meta-analysis of time-domain OCT (TD-OCT) studies showed an estimated RNFL loss of 220.38 mm (95% confidence interval, 222.86 to 217.91) in the ON eyes of MS patients as compared to control eyes (6). In eyes with no evidence of ON, TD-OCT measured RNFL values were reduced by 27.08 mm relative to the eyes of healthy controls, and the estimated RNFL loss in ON eyes vs unaffected eyes of MS patients was -14.57mm (95% confidence interval, 21...

Prefoveal floaters as a differential diagnosis to optic neuritis: “mouches dormantes”

“…Referrals to a neuro-ophthalmology unit include optic neuritis and optic neuropathies [ 1 , 2 , 5 ]. This case series shows that small prefoveal floaters just dense enough to cast a shadow on the retina were the cause for the patients’ central scotomas.…”

“…Should optical coherence tomography (OCT) be part of the routine clinical assessment is a controversially debated topic in the neuro-ophthalmology community [ 1 ]. There are good arguments against routine use of OCT [ 2 , 3 ], and situations were a good case can be made for it [ 4 , 5 ].…”

Optical coherence tomography and multiple sclerosis: Update on clinical application and role in clinical trials

“…79,81,82 Furthermore, variability in pRNFL measures at the individual level complicates the clinical applicability of cohort studies from longitudinal analyses to individual patients. 83 Although estimated annual pRNFL/GCIPL atrophy rates are within the test–retest error range of SD-OCT devices, 72 subtle changes may be difficult to detect over shorter time periods. 84 Therefore, pertinent questions remain regarding the optimal window for longitudinal re-imaging, as well as values that would signify clinically meaningful thickness reductions, therefore potentially warranting alterations in MS treatment.…”

Applications of Optical Coherence Tomography in Pediatric Clinical Neuroscience

“…Still, OCT has been recommended by some to obtain a "baseline" cpRNFL thickness performed 6 months after the optic neuritis attack. 57 Subsequent scans could be obtained to assess the effects of additional attacks or for disease progression; however, such data should be interpreted with caution as longitudinal studies are limited in adults and have not been published in pediatrics.…”