Choroidal Thickness in Multiple Sclerosis: An Optical Coherence Tomography Study

Abstract

Background and purpose: To identify changes in the choroidal thickness (CT) in multiple sclerosis (MS) patients with and without optic neuritis (ON) using enhanced-depth-imaging optical coherence tomography (EDI-OCT).

Methods: This cross-sectional study included 96 eyes with MS and 28 eyes of healthy controls. All participants underwent an ophthalmologic examination and EDI-OCT scanning (Spectralis, Heidelberg Engineering, Germany) to assess the CT and the retinal nerve fiber layer (RNFL) thickness. MS patients were divided into two groups: 1) with and 2) without a history of ON. The CT was evaluated in the fovea and at six horizontal and six vertical points at 500, 1,000, and 1,500 µm from the fovea. Paired t-tests were used to compare the groups, and p-value<0.05 was considered as significant.

Results: At all 13 measurements points, the CT was thicker in MS patients than in the healthy controls and was thinner in eyes with ON than in the contralateral eyes, but these differences were not statistically significant. However, the CT was always larger in all points in eyes with a history of ON than in the control eyes. The RNFL was significantly thinner (p<0.05) in both MS and ON eyes than in the control eyes.

Conclusions: The CT did not differ between MS and control eyes, but it was significantly larger in patients with a history of ON, in whom the RNFL was thinner. Further studies are necessary to establish the possible role of the choroid in MS.

Keywords: choroidal thickness; multiple sclerosis; optic neuritis; optical coherence tomography (OCT).

Fig. 1. Horizontal (A) and vertical (B) macular and choroidal scans with thickness measurements in a right eye. The green line is manually positioned on the fovea, and the yellow lines indicate measurements of the choroidal thickness.

Fig. 2. Optical coherence tomography (OCT) print-out. Peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography in a healthy control (A) and a multiple sclerosis patient (B). In both images there is a fundus photo with a green circle which indicates where the measurements have been done (up left); the long image shows an OCT scan of the retina structure along the green circle (up right); in the circle thre are the mean values of the RNFL calculated for six sector and globally together with a statistical classification (image A: within normal limits, image B: below normal limits) (down left); the long coloured image is the peripapillary RNFL thickness profile (down right). The three colour rappresent the normal limit of the measurements (green), the borderline (yellow) and the below normal limits (red). I (INF), inferior; N (NAS), nasal; NI, nasal inferior; NS, nasal superior; N/T, nasal temporal ratio; PMB, papillary-macular bundle; S (SUP), superior; T (TMP), temporal; TI, temporal inferior; TS, temporal-superior.