Progressive Functional and Neuroretinal Affectation in Patients With Multiple Sclerosis Treated With Fingolimod

To evaluate the effect of fingolimod in visual function and neuroretinal structures in patients with multiple sclerosis (MS) for a period of 1 year.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Progressive Functional and Neuroretinal Affectation in Patients With Multiple Sclerosis Treated With Fingolimod Elena Garcia-Martin, PhD, Erika Ruiz de Gopegui, PhD, Maria Satue, Laura Gil-Arribas, PhD, Laura Jarauta, MD, Jose R. Ara, PhD, Jesus Martin, PhD, Francisco J. Fernandez, PhD, Elisa Vilades, MD, Maria J. Rodrigo, PhD Background: To evaluate the effect of fingolimod in visual function and neuroretinal structures in patients with multiple sclerosis (MS) for a period of 1 year. Methods: This longitudinal and observational cohort study included 78 eyes of 78 patients with MS treated with fingolimod. All subjects were evaluated every 3 months during 12 months and compared with 32 patients treated with interferon beta. All patients were examined for highcontrast and low-contrast (2.5% and 1.25%) visual acuity (VA), contrast sensitivity vision (CSV) (using Pelli–Robson and CSV-1000E tests), color vision (Farnsworth D-15 and L’Anthony D-15 desaturated tests), and retinal structural measurements (retinal nerve fiber layer [RNFL] and ganglion cell layer [GCL] thickness) using optical coherence tomography (OCT) technology. Results: Patients with MS treated with fingolimod for a period of 1 year showed significant reduction in 100% and 1.25% contrast VA (P = 0.009 and 0.008, respectively), an alteration of contrast sensitivity and color perception (Pelli–Robson test, CSV-1000E test, Farnsworth D-15 desaturated test, and L’Anthony D-15 desaturated test; P , 0.001), GCL thickness reduction (P = 0.007), and an average macular central thickness increase of 2.6 mm (P = 0.006). Patients with MS treated with interferon beta did not show significant changes in visual function tests neither in macular thickness measurements, but they showed a significant reduction in GCL and RNFL thicknesses. The reduction in neuroretinal structures observed by OCT was significantly higher in the interferon-beta group, but patients treated with fingolimod showed a significant increase in Ophthalmology Department (EG-M, ERG, MS, LG-A, FJF, EV, MJR), Miguel Servet University Hospital, Zaragoza, Spain; Aragon Institute for Health Research (IIS Aragon) (EG-M, ERG, MS, LG-A, LJ, JRA, JM, FJF, EV, MJR), University of Zaragoza, Zaragoza, Spain; and Neurology Department (LJ, JRA, JM), Miguel Servet University Hospital, Zaragoza, Spain. Supported by PI17/01726 (Instituto de Salud Carlos III) and by MAT2017-83858-C2-2 MINECO/AEI/FEDER, UE. The authors report no conflicts of interest. Address correspondence to Elena Garcia-Martin, PhD, C/Padre Arrupe, Consultas Externas de Oftalmología, 50009- Zaragoza, Spain; E-mail: [e-mail] Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 macular central thickness and a reduction in low contrast vision (P , 0.001). Conclusions: Patients with MS treated with fingolimod and with no clinically observable macular edema show a significant change in visual function parameters and average macular central thickness increase compared with those treated with interferon beta. These findings are probably due to subclinical macular edema produced by fingolimod, which might be considered as an indicator for pharmacovigilance of sphingosine-1-phosphate inhibitors to be improved. Journal of Neuro-Ophthalmology 2021;41:e415–e423 doi: 10.1097/WNO.0000000000000991 © 2020 by North American Neuro-Ophthalmology Society V isual impairment is a key manifestation of multiple sclerosis (MS). Acute optic neuritis is a common, often showing manifestation of MS, but visual deficits and structural loss of retinal axonal and neuronal integrity can occur even without a history of optic neuritis. Partially in reaction to the improvement in sensitive visual function evaluations, structural markers consisting of optical coherence tomography (OCT) and MRI, and quality of life measurements which give medical meaning to the structure–function correlations that are unique in the afferent visual pathway (1), interest in vision in MS is growing. Abnormal eye movements are also common in MS. The low-contrast visual acuity (VA) has emerged as the main choice to measure visual impairment in MS. It is related with vision-specific quality-of-life measurements, providing information on medical relevance, and with the structural integrity of the retina measured by OCT. In addition, these factors have resulted in fast accumulation of information about visual impairment in optic neuritis and MS (2). Fingolimod (FTY720 [Gilenya, Novartis Pharmaceuticals, Basel, Switzerland]) is an immunotherapeutic drug targeting the sphingosine-1-phosphate receptor. It was e415 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution regarded as the first oral disease-modifying therapy for the relapsing types of MS by the US FDA in 2010, and eventually by the European Medicines Agency in 2011 (3,4). It belongs to a class of molecules addressing the sphingolipid-regulated signaling system. The medical outcomes of this agent, confirmed in several massive, randomized, and controlled scientific trials of patients with relapsing–remitting MS (RRMS), consisted of an early and sustained impact on brain atrophy (5–7). Potential side effects such as bradycardia, infections, atrioventricular block, skin cancer, teratogenicity, and progressive multifocal leukoencephalopathy might appear during therapy with fingolimod; reactivation of MS activity may happen after fingolimod cessation; therefore, patients should be closely monitored for disease activity for several months after abandoning fingolimod therapy (8,9). Concerning the eye and although its incidence is low (10–12), fingolimod-associated macular edema is recognized as an adverse drug reaction during fingolimod therapy for MS. Generally, fingolimod is simply interrupted when this sort of edema appears, and in most cases, it gets better without the need for other drugs (7). The effects of MS on the central nervous system are generally difficult to examine directly, but the retinal nerve fiber layer (RNFL) and the ganglion cell layer (GCL) can be measured to directly assess neurons and axonal damage by using OCT (13–17). However, only a few authors have examined the effects of MS treatments on visual function or RNFL/GCL degeneration, including fingolimod, with the particularity of the associated macular edema. METHODS This is a cohort observational longitudinal study. Cohort Description We performed a prospective longitudinal study with a 12month follow-up. Seventy-eight eyes from 78 patients with RRMS treated with fingolimod were evaluated at baseline, 3, 6, and 12 months from the beginning of the treatment; and 34 RRMS eyes from 34 patients treated with interferon were studied at baseline treated with interferon and 12 months. Recruitment began in 2018 and evaluations were made between 2018 and 2019. We included only 1 eye from each patient randomly to avoid confusion bias for interrelation between 2 eyes from the same patient. In cases of patients with a history of optic neuritis (ON) only the non-ON eye was selected for the study to avoid bias because of atrophy secondary to the inflammatory episode. Patient and public involvement: All processes adhered to the tenets of the Declaration of Helsinki, and the local ethics committee accepted the experimental protocol (Code: 03/ 2012). All participants supplied informed consent to participate in the study, and they were free to stop participating in the study at any time they desired. In the informed consent, e416 the investigator explained the research question and outcome measures to the patients remitted by a neurologist with MS diagnosis. Results of the study were communicated to the patients in each visit and wrote in the clinical history of the patient to be read later by the neurologist. All patients started treatment with fingolimod or interferon beta in less than 2 weeks’ time from the baseline ophthalmic examination. Study Protocol All subjects underwent a complete ophthalmological examination, including anterior segment, pupillary reflex, and funduscopic evaluation to rule out any concomitant eye condition. Only patients with relapsing–remitting MS were included in our study. Patients with VA ,0.1 (6/60, using the Snellen chart), intraocular pressure .20 mm Hg, and/or active MS outbreaks (of any neurologic deficit) in the 6 months preceding enrollment in the study were excluded from the study. Other exclusion criteria included the presence of other retinal pathologies, such as the presence of clinically observable macular edema, retinal atrophy, or other retinal alterations not related to MS that could interfere with OCT measurements. The presence of other neurological pathologies was also ruled out, as well as systemic diseases that could interfere with retinal measurements (such as diabetes mellitus or uncontrolled arterial hypertension). The visual function was assessed through measuring the best-corrected visual acuity using an Early Treatment Diabetic Retinopathy Study (ETDRS) chart with 3 different contrasts (100%, 2.50%, and 1.25%), contrast sensitivity vision (CSV) using the CSV-1000E test and the Pelli– Robson test, and color vision by the Farnsworth desaturated D-15 and L’Anthony desaturated D-15 tests. All visual function measurements were obtained under monocular and binocular vision, with best correction, and controlled light conditions (photopic, high mesopic, and low mesopic). In addition, the Expanded Disability Status Scale (EDSS) score was evaluated. CSV is a preferable means to test visual function compared with VA. The CSV-1000E test and the Pelli– Robson test are the 2 tests used in its measurement. The “contrast threshold” is the lowest contrast necessary for a set of bands and letters to be noticed by the eye. The CSV1000E device is used globally for standardized CSV and glare examination. At a distance of 2.5 m from the chart under monocular vision at 4 different spatial frequencies (3, 6, 12, and 18 cycles per degree [cpd]), all patients were evaluated, and a CSV curve was generated. The Pelli– Robson chart comprises horizontal traces of capital letters over a white background, organized in triplets, with 2 triplets per line, with each triplet having the same contrast: the contrast decreases from 1 triplet to the next. Color vision was evaluated through the Color Vision Recorder program, a piece of software which examines chromatic discernment by arrangement of colors. It Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution comprises the conventional tests of Farnsworth 100-hue (FM-100), Farnsworth–Munsell D15, and L’Anthony D-15 (18,19). All patients in the study underwent an evaluation using the Farnsworth–Munsell D15 and L’Anthony D-15 protocols (commonly used to differentiate between patients with severe loss of color vision and those with milder or normal color vision and or defects), and distinguished output parameters together with the Confusion Index(C-index), the Color Confusion Index, the Confusion angle (Conf Ang), and the Scatter Index (S-index) were recorded. Structural examination of the retina was performed using spectral-domain OCT with the Cirrus high-definition OCT system (Carl Zeiss Meditec Inc, Dublin, CA) and the ganglion cell protocol (for individual analysis of this layer). The OCT device was an identical experienced operator. An internal fixation objective was used because it presents the highest reproducibility. Image quality assessment depended on the signal strength measurement that connects the signal-to-noise ratio with the uniformity of the signal within a scan (scale 1–10, being 1 poor image quality and 10 excellent). Images included for testing had a quality score higher than 7. Scan acquisition followed the OSCAR-IB criteria and scans were rejected after published recommendations on decentration, poor scan quality, boundary line errors or algorithm failures, and none of the retinal diseases included as to be considered in these criteria was present. The Cirrus OCT macular cube 512 · 128 protocol offers a macular volume measure and retinal thickness values for 9 regions, which correspond to the ETDRS. These areas include a central 1-mm circle interpreting the fovea, an inner ring measuring 3 mm, and an outer ring measuring 6 mm in diameter. These rings are separated into 4 quadrants each: superior, nasal, inferior, and temporal. The Cirrus OCT optic disc protocol generates 200 · 200 cube images with 200 linear scans, allowing for examination of the RNFL of a 6-mm3 area around the optic nerve. For every scan series of RNFL evaluation, the mean, superior, inferior, temporal, and nasal thickness were measured. Cirrus segmentation analysis for retinal layers also provides measurements of the GCL thickness, evaluating 6 areas of the macular cube (superior, superonasal, inferonasal, inferior, inferotemporal, and superotemporal sectors), and measurements of the mean and minimum GCL and the inner plexiform layer (GCL + IPL) value of a set of 360 spokes, in which each average outcome stands for the mean number of pixels along that spoke which is located within the measurement annulus. The minimum is chosen because the thinnest portion of the GCL + IPL within the perifoveal region is regarded to imply damage to the ganglion cells. Statistical Analysis All data analyses were performed using SPSS software version 20.0 (SPSS Inc, Chicago, IL). The Kolmogorov– Smirnov test used to assess sample distribution excluded Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 standard values, so the Wilcoxon nonparametric test for paired samples was used in the quantitative data analysis. For the qualitative data, the x2 test was performed. The Bonferroni correction for multiple comparisons was used in all analyses, and values of P # 0.05 were considered to indicate the statistical significance. The linear correlation between structural and functional parameters was established through the Spearman correlation coefficient. All-important data and results are provided in the article. Data not provided in the article because of space limitations will be shared at the request of other investigators for the purpose of replicating procedures and results. Anonymized data will be shared on request from any qualified investigator. RESULTS Fingolimod Group The fingolimod group was composed by 78 RRMS patients, 14 men (17.95%) and 64 women (82.95%). In the group treated with fingolimod, 30.77% patients had been treated with fingolimod as their first treatment; on the other hand, 42.72% patients had previously been treated with interferon, 12.82% patients had been treated with glatiramer acetate, and 7.69% patients had been treated with natalizumab. The mean EDSS at the beginning of the study was 2.70 ± 2.01 and 2.71 ± 1.88 in the 1-year visit (P . 0.05). A relative afferent pupillary defect (RAPD) was found in 4 patients (5.12%). A total of 20 patients had a history of optic neuritis in at least 1 eye (25.64%), with a minimum distance of 6 months from the active episode to the inclusion in the study. The functional analysis in the fingolimod group demonstrated that Farnsworth showed alterations at the baseline visit in 12 patients (15.39%) and normal results in 66 patients (84.61%). The L’Anthony D-15 test was normal in 30 cases (38.47%) and altered in 48 patients (61.53%). Visual function parameters at the baseline and at 3, 6, and 12 months are shown in Table 1. Significant reduction in monocular and binocular VA measured at low contrast conditions (1.25%) were found after 12 months of nonstop treatment with fingolimod (P = 0.009 and 0.008, respectively). Contrast sensitivity measured with the Pelli–Robson chart, monocularly and binocularly, showed a significant slow and progressive deterioration at 6-month and 12month examination (P , 0.001). Contrast sensitivity measured with CSV-1000 did not find any significant differences in any of the 4 frequencies analyzed along the 12 months of follow-up. Color vision examination (L’Anthony test indexes and Farnsworth test indexes) did not find statistically differences in the progressive 3-month, 6-month, or 12-month visits. e417 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 1. Functional parameters obtained at baseline and at 3-, 6-, and 12-month examinations in the fingolimod group Baseline 3-Month Visit Visual Functional Test Fingolimod Group Mean ± SD Mean ± SD AV 100% AV 100% AO AV 2.5% AV 2.5% AO AV 1.25% AV 1.25% AO Pelli–Robson Pelli–Robson AO CSV frequency A CSV AO frequency CSV frequency B CSV AO frequency CSV frequency C CSV AO frequency CSV frequency D CSV AO frequency 0.08 0.04 0.56 0.43 0.69 0.56 1.68 1.79 1.64 1.71 1.80 1.94 1.41 1.64 0.98 1.15 A B C D 0.09 0.06 0.59 0.43 0.71 0.57 1.72 1.85 1.60 1.76 1.81 1.95 1.41 1.52 0.96 1.14 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.17 0.15 0.24 0.20 0.22 0.21 0.32 0.30 0.42 0.49 0.39 0.42 0.41 0.44 0.35 0.39 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.19 0.13 0.28 0.15 0.17 0.18 0.23 0.20 0.20 0.18 0.21 0.16 0.34 0.19 0.30 0.23 6-Month Visit 12-Month Visit P value (With P value (With P value (With Basal Visit) Mean ± SD Basal Visit) Mean ± SD Basal Visit) 0.119 0.016 0.355 0.783 0.045 0.825 0.010* 0.009* 0.656 0.274 0.517 0.945 0.516 0.136 0.327 0.405 0.08 0.04 0.61 0.42 0.74 0.56 1.63 1.72 1.54 1.61 1.76 1.90 1.41 1.44 0.89 0.93 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.24 0.39 0.19 0.18 0.22 0.21 0.31 0.36 0.21 0.19 0.31 0.25 0.37 0.46 0.43 0.48 0.123 0.015 0.613 0.414 0.039 0.189 ,0.001* ,0.001* 0.543 0.123 0.847 0.097 0.404 0.109 0.798 0.371 0.13 0.05 0.58 0.41 0.66 0.53 1.64 1.71 1.64 1.74 1.83 1.97 1.40 1.65 1.01 1.19 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.20 0.14 0.19 0.12 0.17 0.16 0.20 0.12 0.20 0.12 0.19 0.16 0.33 0.18 0.29 0.22 0.013 0.087 0.520 0.612 0.009* 0.008* ,0.001* ,0.001* 0.432 0.216 0.501 0.732 0.663 0.578 0.341 0.498 Results reported as mean and SD in parentheses. Values of P , 0.05 were considered to indicate the statistical significance. *Statistical significance using the Bonferroni correction for multiple comparisons. CSV, contrast sensitivity vision. The retinal structure analysis in the fingolimod group proved significant differences between the baseline and the 12-month examination are shown in Table 2. We detected a significant increase in central macular thickness (P = 0.006); however, a significant reduction was found in the macular temporal area of the outer ring (P = 0.002). The average GCL value was significantly reduced when comparing the baseline and the 12-month visits (P = 0.007), and also, a significant reduction was found when analyzing the GCL division in the inferior sector (P = 0.008), nasal inferior (P = 0.009), nasal superior (P , 0.001), and temporal inferior (P = 0.002) (Fig. 1). RNFL comparisons showed differences when analyzing the RNFL hour sectors 8, 11, and 12, with a significant increment in thickness (P = 0.001, P = 0.002, and P = 0.001, respectively). Correlation analysis was performed to determine the association between the changes in visual function parameters and structural variables during the follow-up. The correlation was of mild–moderate strength but did not prove significant when using the Bonferroni correction for multiple comparisons. The functional analysis at the baseline visit of the interferon group demonstrated alterations in 7 patients (20.58%) in Farnsworth D-15 test and 18 patients (52.94%) in L’Anthony D-15 test. Visual function parameters at the baseline and at 12 months are shown in Table 3. Reductions in monocular and binocular VA measured at low-contrast conditions (1.25%) were found after 12 months of nonstop treatment with interferon, but the changes were not significant using the Bonferroni correction (P = 0.025 and 0.031, respectively). The neuroretinal analysis by OCT in the interferon group showed significant differences between the baseline and the 12-month examination (Table 4) in all GCL thicknesses (P # 0.008); in RNFL average thickness; and in superior, inferior, and temporal RNFL sector thicknesses (P # 0.007). Macular thickness did not show significant changes. Correlation analysis between the changes in functional and structural variables during the follow-up did not show significant associations. Interferon Group Before this analysis, no significant differences in EDSS and OCT parameters were found between the fingolimod group and the interferon group at the baseline visit. Comparison of the change in variables during the 1-year follow-up in both groups of patients with MS is represented in Tables 3 and 4. The fingolimod group showed higher low-contrast VA change (with monocular and binocular vision) in the 1- The interferon group was composed by 34 RRMS patients, 6 men (17.65%) and 28 women (82.35%), and a RAPD was found in 1 patient (2.94%). A total of 8 patients had a history of optic neuritis in at least 1 eye (25.00%), with a minimum distance of 6 months from the active episode to the inclusion in the study. The mean EDSS was 2.67 ± 1.78 at the beginning of the study and 2.69 ± 1.85 at 1 year. e418 Comparison of Changes Between Fingolimod and Interferon Groups Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 2. Structural parameters obtained at baseline and at 3-, 6-, and 12-month examinations in the fingolimod group OCT Parameters in the Fingolimod Group Macular thickness (ETDRS sectors) Macular central Macular superior inner Macular nasal inner Macular inferior inner Macular temporal inner Macular superior outer Macular nasal outer Macular inferior outer Macular temporal outer Ganglion cell analysis (GCL) GCL average GCL superior GCL inferior GCL nasal inferior NI GCL nasal inferior NS GCL temporal inferior TI GCL temporal superior TS Retinal nerve fiber layer (RNFL) protocol (quadrants and sectors) RNFL average RNFL superior quadrant RNFL nasal quadrant RNFL inferior quadrant RNFL temporal quadrant RNFL hour sector 1 RNFL hour sector 2 RNFL hour sector 3 RNFL hour sector 4 RNFL hour sector 5 RNFL hour sector 6 RNFL hour sector 7 RNFL hour sector 8 RNFL hour sector 9 RNFL hour sector 10 RNFL hour sector 11 RNFL hour sector 12 Basal Visit 253.24 ± 21.14 312.05 ± 19.9 312.87 ± 20.64 307.61 ± 19.83 300.02 ± 18.92 275.84 ± 16.30 285.28 ± 19.90 263.04 ± 15.61 258.80 ± 15.08 74.53 ± 13.34 75.49 ± 10.72 74.46 ± 11.97 73.30 ± 11.47 73.81 ± 10.04 75.69 ± 9.78 74.54 ± 9.99 84.47 104.09 68.81 112.35 52.67 105.50 96.59 86.63 55.39 64.33 99.07 128.99 109.05 52.38 43.38 63.37 111.20 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 14.08 19.32 13.47 23.02 13.14 28.28 22.84 22.85 11.51 13.78 25.75 33.01 26.65 14.86 11.53 18.62 26.68 6-Month Visit 3-Month Visit 255.83 313.03 313.83 307.72 299.75 278.17 285.74 262.51 259.78 ± ± ± ± ± ± ± ± ± 20.46 21.49 23.55 21.39 21.87 19.07 22.01 16.53 15.91 72.88 ± 9.95 73.41 ± 10.04 73.79 ± 12.20 71.59 ± 11.52 71.62 ± 10.62 73.94 ± 10.31 72.79 ± 9.33 82.42 104.21 65.68 108.95 50.63 108.63 95.42 81.05 55.79 59.53 96.37 130.68 99.63 48.11 42.58 61.37 108.53 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 18.22 18.55 17.27 36.62 10.01 28.11 21.34 21.81 15.84 17.37 38.09 51.58 31.99 19.13 12.45 10.35 21.47 255.40 304.25 305.60 307.95 291.55 267.05 275.30 252.70 249.25 ± ± ± ± ± ± ± ± ± 12-Month Visit Change (12 mo) P value 19.47 15.43 16.86 17.25 15.64 14.48 67.02 12.97 10.78 255.84 311.88 312.41 307.85 298.47 279.84 288.47 264.03 255.39 ± ± ± ± ± ± ± ± ± 23.93 25.01 25.83 23.98 24.33 22.19 21.99 18.65 26.72 2.60 20.17 20.46 0.24 21.55 4.00 3.19 0.99 23.41 0.006* 0.243 0.439 0.314 0.065 0.001* 0.002* 0.047 0.002* 69.60 ± 8.51 71.10 ± 9.04 68.90 ± 9.41 67.90 ± 10.14 68.70 ± 8.76 70.75 ± 9.26 70.20 ± 8.70 72.53 74.25 72.66 71.75 70.16 73.09 73.31 ± ± ± ± ± ± ± 12.10 12.21 14.18 12.58 14.97 12.25 10.52 22.00 21.24 21.8 21.55 23.65 22.60 21.23 0.007* 0.015 0.008* 0.009 ,0.001* 0.002* 0.018 88.22 ± 11.48 109.80 ± 19.28 66.14 ± 12.87 116.77 ± 19.64 59.51 ± 14.93 105.51 ± 25.99 97.14 ± 21.48 81.34 ± 18.93 53.69 ± 8.96 63.51 ± 21.65 95.86 ± 26.44 130.94 ± 29.88 123.49 ± 27.84 56.74 ± 19.92 46.74 ± 10.53 76.40 ± 19.43 126.37 ± 26.58 3.75 5.71 22.67 4.42 6.84 0.01 0.55 25.29 21.70 20.82 23.21 1.95 14.44 4.36 3.36 13.03 15.17 0.009 0.004 0.016 0.008 0.004 0.764 0.700 0.005 0.132 0.345 0.012 0.371 0.001* 0.090 0.014 0.002* 0.001* 84.71 ± 10.23 107.29 ± 15.93 67.92 ± 8.51 112.86 ± 10.00 50.86 ± 7.63 107.50 ± 25.94 104.71 ± 18.44 84.50 ± 17.03 52.93 ± 7.51 66.07 ± 12.66 102.93 ± 19.58 125.21 ± 15.19 139.86 ± 92.78 45.64 ± 10.05 42.93 ± 12.79 64.14 ± 11.08 109.57 ± 26.63 Results reported as mean and SD in parentheses. Values of P , 0.05 were considered to indicate the statistical significance. *Statistical significance using the Bonferroni correction for multiple comparisons. GCL, ganglion cell layer; RNFL, Retinal nerve fiber layer. year follow-up than the interferon group (P , 0.001) (Table 3). The reduction in GCL average thickness structures by OCT was significantly higher in the interferon group (P , 0.006) and in RNFL average, superior, inferior, and temporal RNFL sector thicknesses (P , 0.001). Patients treated with fingolimod presented a significant increase in macular central thickness (in foveal, inferior inner, and inferior outer sectors) and reduction in low-contrast vision compared with patients treated with interferon (P , 0.007) (Table 4). Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 DISCUSSION Macular edema is a prominent adverse event reported in diverse studies about fingolimod safety (10,20,21). However, in this study, we have analyzed and quantified changes in the visual function objective and measurable parameters and identified potential changes in the retinal morphological structure among patients with RRMS being treated with fingolimod, with a 12-month follow-up, being this, to the best of our knowledge, the first study with these characteristics. e419 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 1. Macular central thickness and ganglion cell layer (GCL) average thickness during the 1-year follow-up in the group of patients treated with fingolimod. The slight decrease–increase slope at 6–12 months can be observed in the GCL. Measurements in the Y axis are in microns. The overall goal of this study is to describe and characterize the changes exclusively because of this pharmacological treatment; in particular, not the changes observed in other patients with MS and caused by the neurodegenerative process itself, and the aim was to establish the differences between macular edema and other alterations clearly. The VA is most of the times the only objective parameter about visual function or quality, which is measured in routine ophthalmologic examinations, but contrast sensitivity evaluation is a much more valuable test, able to identify visual impairment in early stages, especially when measured in high spatial frequencies. We evaluated the visual function by quantifying not only the VA, which is most of the times the only objective parameter about visual function or quality measured in routine ophthalmologic examinations, but also the VA at 3 different contrast levels, providing much more information. Sensitive visual outcome measurements are relevant when examining the effect of treatment because visual dysfunction is one of the most common manifestations of MS. In addition, patients with MS often show subclinical changes in visual function without apparent visual symptoms. Such impairments can remain undetected because of the lack of sensitivity of some visual function assessments, particularly those based solely on the high-contrast acuity. The tests which measure low-contrast vision (with shades of grey on a white background) are more sensitive medical measurements of visual disorder in MS and can detect abnormalities even in patients with MS with otherwise evident good VA. One of such tests used in our evaluation of patients was the Pelli–Robson chart, which measure contrast sensitivity at a spatial frequency of 1 cpd, and it was used in the Optic Neuritis Treatment Trial (22). Thus, it became a practical and sensitive indicator of visual disorder in optic neuritis. In our study, we have found a slight alteration in the VA when measured at low-contrast conditions, but it is much more remarkable than the significant finding of a progressive dysfunction in the contrast sensitivity perception when measured with Pelli–Robson along 12 months of follow-up. TABLE 3. Functional parameters obtained at baseline and 12-months examinations in the interferon group and significance of change during the follow-up Baseline 12-Month Visit Visual Functional Test Interferon Group Mean ± SD Mean ± SD AV 100% AV 100% AO AV 2.5% AV 2.5% AO AV 1.25% AV 1.25% AO Pelli–Robson Pelli–Robson AO CSV frequency A CSV AO frequency CSV frequency B CSV AO frequency CSV frequency C CSV AO frequency CSV frequency D CSV AO frequency 0.09 0.07 0.61 0.49 0.74 0.61 1.70 1.80 1.66 1.80 1.92 1.97 1.48 1.56 0.98 1.17 0.10 0.08 0.60 0.50 0.77 0.64 1.68 1.76 1.65 1.78 1.90 1.97 1.47 1.55 0.99 1.15 A B C D ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.19 0.18 0.29 0.24 0.27 0.25 0.29 0.33 0.39 0.38 0.37 0.48 0.39 0.39 0.40 0.29 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.25 0.17 0.18 0.15 0.19 0.15 0.27 0.23 0.41 0.22 0.24 0.22 0.33 0.27 0.31 0.28 P value (With Basal Visit) P value (Change in Fingolimod vs Interferon) 0.103 0.140 0.443 0.348 0.025 0.031 0.109 0.099 0.649 0.190 0.220 0.365 0.601 0.490 0.298 0.309 0.032 0.098 0.329 0.432 ,0.001* ,0.001* 0.133 0.188 0.342 0.453 0.366 0.290 0.593 0.481 0.762 0.808 The last column represents the significance of the comparison between 12-month changes between interferon and fingolimod groups. Results reported as mean and SD in parentheses. Values of P , 0.05 were considered to indicate the statistical significance. *Significance using the Bonferroni correction for multiple comparisons. CSV, contrast sensitivity vision; OCT, optical coherence tomography. e420 Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 4. Structural parameters obtained at baseline and 12-month examination in the interferon group OCT Parameters in Interferon Group Macular thickness (ETDRS sectors) Macular central Macular superior inner Macular nasal inner Macular inferior inner Macular temporal inner Macular superior outer Macular nasal outer Macular inferior outer Macular temporal outer Ganglion cell analysis (GCL) GCL average GCL superior GCL inferior GCL nasal inferior NI GCL nasal inferior NS GCL temporal inferior TI GCL temporal superior TS Retinal nerve fiber layer (RNFL) protocol (quadrants and sectors) RNFL average RNFL superior quadrant RNFL nasal quadrant RNFL inferior quadrant RNFL temporal quadrant RNFL hour sector 1 RNFL hour sector 2 RNFL hour sector 3 RNFL hour sector 4 RNFL hour sector 5 RNFL hour sector 6 RNFL hour sector 7 RNFL hour sector 8 RNFL hour sector 9 RNFL hour sector 10 RNFL hour sector 11 RNFL hour sector 12 Basal Visit 12-Month Visit Change (12 mo) P (1) P (2) ,0.001* 0.076 0.932 0.007* 0.772 0.010 0.102 0.006* 0.412 256.43 312.33 311.08 305.55 298.44 274.69 280.18 264.83 260.32 ± ± ± ± ± ± ± ± ± 19.02 17.99 21.51 18.03 18.11 17.77 21.19 16.61 17.79 255.38 312.70 310.67 304.25 296.54 275.45 281.95 263.93 258.31 ± ± ± ± ± ± ± ± ± 18.44 23.70 24.48 26.71 23.76 23.79 19.19 17.09 19.10 21.05 0.37 20.41 21.30 21.90 0.76 1.77 20.90 22.01 0.074 0.348 0.521 0.529 0.081 0.660 0.104 0.555 0.091 77.31 77.98 75.21 75.88 75.01 77.07 75.63 ± ± ± ± ± ± ± 16.90 14.21 12.22 11.93 12.65 11.15 10.72 73.52 75.97 73.10 73.98 71.89 74.17 73.84 ± ± ± ± ± ± ± 13.44 15.41 16.09 15.34 17.80 15.12 13.61 23.79 22.01 22.11 21.90 23.12 22.90 21.79 ,0.001* 0.006* 0.005* 0.003* ,0.001* ,0.001* 0.008 0.006* 0.315 0.192 0.440 0.398 0.243 0.308 86.21 106.44 69.01 114.76 52.07 106.00 97.79 88.32 56.01 63.19 98.02 129.11 111.58 53.90 46.14 64.85 110.37 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 17.65 20.45 16.98 25.51 17.31 27.00 28.11 25.10 17.92 16.19 29.23 29.01 31.29 24.46 17.21 22.27 28.82 83.32 103.89 67.03 112.64 50.40 104.49 95.98 84.30 54.99 61.64 95.81 130.06 109.04 50.89 43.58 61.36 106.97 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 18.21 19.12 17.01 23.76 19.03 28.02 25.92 20.20 17.91 20.43 26.98 28.01 30.30 25.11 16.67 23.63 25.98 22.89 22.55 21.98 22.12 21.67 21.51 21.81 24.02 21.02 21.55 22.21 0.95 22.54 23.01 22.56 23.49 23.40 0.004* 0.006* 0.043 0.007* 0.005* 0.432 0.543 0.005* 0.243 0.404 0.043 0.606 0.010 0.008 0.023 0.006* 0.007* ,0.001* ,0.001* 0.105 ,0.001* ,0.001* 0.027 ,0.006* 0.329 0.481 0.598 0.721 0.255 ,0.001* ,0.001* ,0.001* ,0.001* ,0.001* Results reported as mean and SD in parentheses. P (1) represents the significance when compared the interferon group between basal and 1-year visit. P (2) represents the significance when compared change during the 1-year follow-up in the fingolimod group and change in the interferon group. Values of P , 0.05 were considered to indicate the statistical significance. *Statistical significance using the Bonferroni correction for multiple comparisons. GCL, ganglion cell layer; OCT, optical coherence tomography; RNFL, retinal nerve fiber layer. We also observed structural macular changes during the follow-up of patients treated with fingolimod. Macular thickness decreased slightly at 6 months and was followed by a significant increase of central macular thickness at 12 months, compared with base line measurements. This significant increase may be attributed to the high probability of fingolimod inducing macular edema, which is widely accepted as an undesirable side effect from the medication and described by many authors (20,22–24). This subclinical macular edema might only appear after 6 months of treatment after structural changes caused by the natural course of the disease. Garcia-Martin et al: J Neuro-Ophthalmol 2021; 41: e415-e423 Garcia-Martin et al concluded that treatment might be a protective factor against RNFL loss associated with disease progression (25) and such protective effect might also be present in the case of patients treated with Fingolimod. However, it seems clear that there is a need of further longitudinal studies using fingolimod to confirm the potential damage induced directly in the visual pathway, apart from the macular edema already accepted as a secondary effect. In the previous years, the GCL measurement has become a more specific parameter for neurological damage in neurodegenerative disorders than the isolated RNFL measurements, and so has been described in the medical e421 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution literature by Chiara et al (26–28). In our study, we found an alteration in all the GCL variables analyzed, when using the segmentation software for the 12-month follow-up. The RNFL layer seemed to be increased after 12 months. This paradoxical fact may be explained by the macular edema associated with fingolimod because the RNFL measurements include the macula in the Cirrus OCT. However, when analyzing the GCL alone, we observe this apparent increase in the RNFL does not correspond to the real damage found in the GCL. We believe that changes observed in the GCL at 6 months (decrease) correspond to the natural course of the disease affecting the retinal neurons. As observed in macular total thickness, the GCL thickness also increased at 12 months, but the thickness at 1 year was significantly lower than baseline measurements. When comparing groups of treatment, patients using fingolimod seemed to preserve better GCL thickness than patients using interferon beta. However, this result should be interpreted with caution because the increase of the GCL found at 12 months in the fingolimod group might be caused by macular edema affecting segmentation measurements not real loss of ganglion cells. One of the limitations of this study is that patients treated with interferon beta were visited only at baseline and 12-month visit but not after 3 and 6 months. The reason is that our interest was focused on evaluating early macular effect in patients who started with fingolimod based on the previous bibliography, but interferon beta treatments have been used for many years; their effect in OCT thicknesses is well known, and no evidence of macular affectation has been found (22–24). Another potential limitation of the study is that the previous treatment which the patients had received (before being included in the study) could have affected some of the parameters studied to some extent. We have tested that no differences existed between fingolimod and interferon groups at the beginning of the study in functional and structural parameters and neither in the disability score (EDSS) that was used to represent the severity scale in these patients with MS. The macular volume increase secondary to fingolimod should be taken into consideration when evaluating visual function and retinal OCT measures in these patients. The alteration in contrast sensitivity vision might be a sign of early subclinical macular edema, and further structural evaluation should be performed to confirm the presence of possible incipient macular changes. Further psychophysical and structural evaluations of vision in patients taking fingolimod may be helpful to comprehend this phenomenon better. 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