Optical Coherence Tomography – A New Monitoring Tool for Multiple Sclerosis? Figure 2: Example of a Patient with a History of Left Optic Neuritis with Complete Recovery Analysis of average RNFL thickness OD
100 200 300
0 0 TEMP 100 SUP 200 NAS 300 400 INF 500 TEMP OS
100 200 300
0 0 TEMP 100 SUP 200 NAS 300 400 INF 500 TEMP Normal distribution percentiles 100% 95% 5% 1% 0%
Imax/Smax Smax/Imax Smax/Tavg Imax/Tavg Smax/Navg
Max – min Smax
Imax Savg Iavg
Avg. thickness
OD (n=1) 0.98 1.02 1.97 1.93 3.02
104.00 144.00 141.00 111.00 97.00 82.16
OS (n=1) 1.00 1.00 2.26 2.26 2.59
90.00
122.00 122.00 93.00
111.00 76.19
OD – OS -0.02 0.02
-0.29 -0.32 0.42
14.00 22.00 19.00 18.00 -14.00 5.97
Circle with different quadrants next to the picture of the optic disc of the left eye shows one quadrant (nasal–superior) with retinal nerve fibre layer (RNFL) thicknesses in the lowest first percentile for age (red). The nasal quadrant of the right quadrant (N, yellow) is slightly but significantly thicker compared with controls. Normal values are expressed in green. The table gives the quantitative values of all quadrants. The last column of the table gives the difference between the eyes. N = nasal quadrant; OD = right eye; OS = left eye; S = superior quadrant; T = temporal quadrant. Source: Carl Zeiss, Stratus.
cross-sectional area of the optic nerve and changes in the amplitude of visual-evoked potential (VEP), implicating axonal loss in this progressive atrophy.39
In ON and MS, axonal loss is an early
pathological feature despite clinical recovery and lack of clinical symptoms. Even in the absence of a history of ON, the eyes of patients with MS have reduced numbers of retinal ganglion cell axons in pathological studies.21
Axonal degeneration in the RNFL of patients with MS, as observed in ophthalmoscopic studies, is detectable in some patients before any visual signs or symptoms of ON have appeared, and has been associated with electrophysiological abnormalities as measured with visual-evoked response testing.41
axonal loss as an early event in the clinical course of MS,42
More recent evidence also supports and optic
nerve atrophy is detectable with MRI within months after a single episode of ON. Recent studies using OCT provide direct evidence that patients with only partial recovery from a single ON episode were found to have significantly reduced RNFL thickness compared with
EUROPEAN NEUROLOGICAL REVIEW
Figure 3: Representative Optical Coherence Tomography Retinal Nerve Fibre Layer Scan Results from a Normal Subject (A) and a Patient with Band Atrophy (B)
AB 42
41 58
99 118 115 69 97 92
63 62
93 S
36 47 N I 111 Signal strength (max 10) 9 T 54 50
83 86
135 106 92 49 45 130 94 67 49 97 Signal strength (max 10) 9 73 T
111 S
I
N
48
The arrows delineate the retinal nerve fibre layer. Source: Monteiro et al., 2004.35
healthy controls. This reduction correlated with the loss of visual acuity. Thinning of the RNFL in these patients was also shown to be significantly correlated with optic nerve atrophy, detected by MRI as reduced optic nerve cross-sectional area.40,43
Even patients with MS
but without a history of ON have been shown to have reduced RNFL thickness compared with healthy controls.44
Visual function correlated 75
Microns
Microns
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