Do eyes with and without optic neuritis in multiple sclerosis age equally?

Figures & data

Table 1 Demographic and clinical characteristics

Number of subjects	56
Sex (male:female)	15:41
Duration of MS (years), mean (SD)	10.01 (6.60)
EDSS, median (range)	2.50 (1.00–5.50)
MS phenotype, n (%)
CIS	6 (10.7)
RR MS	49 (87.5)
SP MS	1 (1.8)
Treatment for MS, n (%)
Interferon	16 (28.8)
Glatiramer acetate	6 (10.7)
Azathioprine	2 (3.6)
Intravenous immunoglobulin	2 (3.6)
Fumarate	1 (1.8)
Natalizumab	9 (16.1)
No treatment	20 (35.7)
Age at ON onset (years), mean (SD)	29.07 (7.95)
Age at baseline OCT (years), mean (SD)	39.08 (7.79)

Abbreviations: CIS, clinically isolated syndrome; EDSS, Expanded Disability Scale Score; MS, multiple sclerosis; OCT, optical coherence tomography; ON, optic neuritis; RR MS, relapsing remitting multiple sclerosis; SP MS, secondary progressive multiple sclerosis.

Table 2 Descriptive characteristics for RNFL parameters (baseline values and changes during follow-up) and their comparison between ON and FL eyes

	ON eyes	FL eyes	P-value
n	56	56
RNFL G baseline (µm), mean (SD)	81.02 (13.02)	90.88 (10.79)	<0.001
RNFL T baseline (µm), mean (SD)	53.93 (13.46)	65.02 (13.39)	<0.001
RNFL N baseline (µm), mean (SD)	59.86 (12.99)	65.70 (14.09)	0.025
Delta RNFL G abs (µm), median (range)	−2.00 (−14.00 to 2.00)	−1.00 (−12.00 to 2.00)	0.620a
Delta RNFL T abs (µm), median (range)	−2.00 (−14.00 to 3.00)	−2.00 (−8.00 to 2.00)	0.404a
Delta RNFL N abs (µm), median (range)	−0.50 (−8.00 to 6.00)	−1.00 (−28.00 to 6.00)	0.346a
Delta RNFL G rel, median (range)	−0.02 (−0.18 to 0.03)	−0.01 (−0.12 to 0.02)	0.386a
Delta RNFL T rel, median (range)	−0.01 (−0.16 to 0.36)	−0.02 (−0.36 to 0.11)	0.440a
Delta RNFL N rel, median (range)	−0.04 (−0.25 to 0.03)	−0.03 (−0.11−0.04)	0.058a
Number of OCT scans, median (range)	5.00 (4.00–10.00)
Length of OCT follow-up (years), mean (SD)	4.57 (1.44)
Median (IQR) [range]	4.42 (3.67–5.49) [2.03–7.29]
ON to baseline interval (years), mean (SD)	5.65 (5.05)
Median (IQR) [range]	4.15 (2.24–7.30) [0.53–23.35]

Notes: RNFL at baseline (in µm) was compared by parametric t-test.

a For non-normally distributed variables, nonparametric Mann–Whitney test was used.

Abbreviations: Delta RNFL G abs, absolute change in RNFL G (mean peripapillary RNFL) between baseline and last scan, respectively, for RNFL N (nasal segment), RNFL T (temporal segment); delta RNFL G rel, change in RNFL G relative to baseline, respectively, for RNFL N, RNFL T; FL eyes, fellow eyes; IQR, interquartile range; OCT, optical coherence tomography; ON, optic neuritis; RNFL, retinal nerve fiber layer.

Table 3 Results of the mixed-effects model using absolute differences between ON and FL eyes’ relative change to baseline

	Beta1	SE	P-value
RNFL G	−0.001965	0.001749	0.262
RNFL N	−0.000215	0.001569	0.891
RNFL T	−0.006963	0.006633	0.295

Notes: The beta1 represents the difference between ON and FL eyes’ relative changes/year. P-values for the comparison of different trends of relative changes are given by Student’s t-tests with Satterthwaite approximations to df.

Abbreviations: df, degrees of freedom; FL eyes, fellow eyes; ON, optic neuritis; RNFL G, mean peripapillary retinal nerve fiber layer thickness; RNFL N and RNFL T, retinal nerve fiber layer thickness for nasal and temporal segment, respectively; SE, standard error.

Figure 1 Mean linear trend for RNFL values.

Notes: The graph shows mean linear trends from baseline for the next 5 years. These trends were estimated using mixed-effects model. The intercept (value on y-axis) denotes mean thickness at the baseline for each parameter (RNFL G, RNFL N, RNFL T) and both (post-ON and fellow) eyes. The paired slopes for both eyes within one RNFL parameter tend to be similar.
Abbreviations: ON, optical neuritis; RNFL, retinal nerve fiber layer; RNFL G, mean peripapillary retinal nerve fiber layer thickness; RNFL N and RNFL T, retinal nerve fiber layer thickness for nasal and temporal segment, respectively.