Dyschromatopsia in Multiple Sclerosis Patients: A Marker of Subclinical Involvement?: Response.

Letters to the Editor on HRR plate testing and D-15 scores but detected a moderate correlation between reduced HRR score and lower contrast sensitivity. We believe in that lower HRR scores are more likely to indicate reduced contrast sensitivity rather than a reduction in color identification or discrimination. The report by Felgueiras et al (1) corroborate the findings of several groups in which reduced contrast sensitivity has been found to be present in a majority of patients with multiple sclerosis, even when there is no visual dysfunction on high-contrast visual acuity testing or a history of optic neuritis (3). We believe that the data presented by Felgueiras et al supports the use of HRR plates as a quick means of assessing contrast sensitivity in a busy clinical setting and in identifying patients who might benefit from treatments to compensate for their contrast sensitivity deficits. Prem S. Subramanian, MD, PhD Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado Jiawei Zhao, MD Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland Dyschromatopsia in Multiple Sclerosis Patients: A Marker of Subclinical Involvement?: Response W e thank Dr. Subramanian and colleagues for their critical appraisal and interest in our article (1). They suggested that Hardy–Rand–Rittler (HRR) pseudoisochromatic plates are not a sensitive indicator of acquired color vision deficits in patients with optic neuropathies. While we agree that a hue discrimination test such as the FarnsworthMunsell (FM) 100 hue test is more sensitive than HRR plate testing, we chose the latter given the fact that it is widely available and easy to perform (2). Moreover, several studies have shown that HRR plates are an effective test of color vision as long as visual acuity is better than 20/50 (3). Use of HRR plates, when compared with the FM 100 hue test, is easier and quicker to perform, and almost all normal subjects would likely make no errors, while in the FM 100 hue test normal subjects would make a few mistakes (2). Zhao et al (4) also bring up an interesting hypothesis that HRR plate testing may be used to screen patients with multiple sclerosis for deficits in contrast sensitivity. One limitation of our study is that contrast sensitivity was not assessed. We look forward to future studies to further address this issue. 108 Department of Biostatistics, Johns Hopkins University School of Public Health, Baltimore, Maryland Sarita B. Davé, MD New York Eye and Ear Infirmary, New York, New York Jiangxia Wang, MS Department of Biostatistics, Johns Hopkins University School of Public Health, Baltimore, Maryland The authors report no conflicts of interest. REFERENCES 1. Felgueiras H, Parra J, Cruz S, Pereira P, Santos AF, Rua A, Meira D, Fonseca P, Pedrosa C, Cardoso JN, Almeida C, Araújo M, Santos E. Dyschromatopsia in multiple sclerosis patients: a marker of subclinical involvement? J Neuroophthalmol. 2016;36:275–279. 2. Zhao J, Davé SB, Wang J, Subramanian PS. Clinical color vision testing and correlation with visual function. Am J Ophthalmol. 2015;160:547–552.e1. 3. Balcer LJ, Frohman EM. Evaluating loss of visual function in multiple sclerosis as measured by low-contrast letter acuity. Neurology. 2010;74:S16–S23. Helena Felgueiras, MD Neurology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal Joana Parra, MD Neurology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal Simão Cruz, MD Neurology Department, Hospital Fernando Fonseca, Lisboa, Portugal Pedro Pereira, MD Neurology Department, Hospital Garcia de Orta, Almada, Portugal Ana F. Santos, MD Neurology Department, Hospital de Braga, Braga, Portugal Adriana Rua, MD Neurology Department, Centro Hospitalar do Porto, Porto, Portugal Letters to the Editor: J Neuro-Ophthalmol 2017; 37: 104-109 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Letters to the Editor Dália Meira, MD Ophthalmology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal Pedro Fonseca, MD Ophthalmology Department, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal Ernestina Santos, MD Neurology Department, Centro Hospitalar do Porto, Porto, Portugal Instituto de Ciências Biomédicas de Abel Salazar da Universidade do Porto, Porto, Portugal The authors report no conflicts of interest. Catarina Pedrosa, MD Ophthalmology Department, Hospital Fernando Fonseca, Lisboa, Portugal João N. Cardoso, MD Ophthalmology Department, Hospital Garcia de Orta, Almada, Portugal Cristina Almeida, MD Ophthalmology Department, Hospital de Braga, Braga, Portugal Maria Araújo, MD Ophthalmology Department, Centro Hospitalar do Porto, Porto, Portugal Letters to the Editor: J Neuro-Ophthalmol 2017; 37: 104-109 REFERENCES 1. Felgueiras H, Parra J, Cruz S, Pereira P, Santos AF, Rua A, Meira D, Fonseca P, Pedrosa C, Cardoso JN, Almeida C, Araújo M, Santos E. Dyschromatopsia in multiple sclerosis patients: a marker of subclinical involvement? J Neuroophthalmol. 2016;36:275–279. 2. Foote KG, Neitz M, Neitz J. Comparison of the Richmond HRR 4th edition and Farnsworth-Munsell 100 Hue Test for quantitative assessment of tritan color deficiencies. J Opt Soc Am A Opt Image Sci Vis. 2014;31: A186–A188. 3. Ng JS, Shih B. Level of visual acuity necessary to avoid falsepositives on the HRR and Ishihara color vision tests. Eur J Ophthalmol. [published ahead of print September 7, 2016] doi: 10.5301/ejo.5000855. 4. Zhao J, Davé SB, Wang J, Subramanian PS. Clinical color vision testing and correlation with visual function. Am J Ophthalmol. 2015;160:547–552.e1. 109 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.