Open Journal of Depression 2013. Vol.2, No.4, 82-86 Published Online November 2013 in SciRes (http://www.scirp.org/journal/ojd) http://dx.doi.org/10.4236/ojd.2013.24014 Open Access 82 Mesopic Visual Contrast Sensitivity in Patients with Major Depression Renata M. T. B. L. Nogueira 1* , Everton L. Espínola 2 , Aline M. Lacerda 2 , Natanael A. Santos 2 1 Departamento de Psicologia da Universidade Federal de Pernambuco (UFPE), Recife, Brasil 2 Laboratório de Percepção, Neurociências e Comportamento, Departamento de Psicologia, Universidade Federal da Paraíba (UFPB), João Pessoa, Brasil Email: * rm_renata@yahoo.com.br Received October 3 rd , 2013; revised November 3 rd , 2013; accepted November 11 th , 2013 Copyright © 2013 Renata M. T. B. L. Nogueira et al. This is an open access article distributed under the Crea- tive Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any me- dium, provided the original work is properly cited. The present study evaluated the effects of major depression on visual contrast sensitivity (CS) at low mesopic luminance (.7 cd/m 2 mean luminance), a condition that has been little explored in the literature. We measured spatial visual CS in 20 male volunteers aged 20 - 30 years, including 10 healthy individuals and 10 medicated individuals with major depression, to linear sine-wave gratings of .25, 1.0, and 4.0 cycles per degree (cpd) of visual angle using the psychophysical staircase method with forced choice. The average spatial visual CS in the depressed group was approximately 1.7 lower than the average spatial visual CS in the control group. However, the post hoc test showed significant differences only at the spatial frequencies of .25 and 1.0 cpd (p < .05), which are likely processed by the magnocellular visual pathway. These results suggest that spatial visual CS to sine-wave gratings should be used to evaluate the responsiveness of the visual system in patients with major depression under conditions of low luminance. Keywords: Visual Perception; Contrast Sensitivity; Depression; Spatial Frequency; Psychophysics Introduction Depression can be defined as a mental disorder presented by depressed mood, loss of pleasure and interest, feelings of guilt and low self-esteem, sleep and appetite disturbances, low en- ergy, and poor concentration (WHO, 2012). The annual inci- dence of depression makes it one of the most important public health problems, with severe socioeconomic implications, high costs for health care, and a reduction of quality of life (Solomon, 2002). According to the World Health Organization (WHO, 2001), severe depression is the leading cause of disability and ranks fourth among the 10 leading causes of pathology world- wide. In fact, by 2020, depression is estimated to be the second leading cause of disability worldwide. Studying depression us- ing different approaches can complement clinical research and contribute to the characterization of the basic cognitive, affec- tive, and neurophysiological mechanisms of this disease. It may also reveal new theoretical, behavioral, and functional aspects of depression in general and highlight alternative means of diagnosis and prognosis. The present study used visual contrast sensitivity (CS) to assess the perception of patients with major depression. Visual CS is one of the most widely used tools in the diagno- sis and theoretical and clinical evaluation of changes in visual perception and alterations in the central nervous system (Wes- ner & Tan, 2006) caused by disorders or diseases, such as schizophrenia (Slaghuis & Thompson, 2003), amblyopia (Polat, Sagi, & Norcia, 1997), cataracts (Elliott & Situ, 1998), mercury poisoning (Ventura et al., 2005), stroke (Santos & Andrade, 2012; Santos, Andrade, & Fernandez Calvo, 2013), and Alzheimer’s and Parkinson’s diseases (Polat et al., 1997; Akutsu & Legge, 1995; Bour & Apkarian, 1996; Vleugels et al., 1998). Surveys related to visual CS and affective disorders are still sparse, with only a few studies performed under different con- ditions and for different purposes (Wesner & Tan, 2006; Ca- valcanti & Santos, 2005; Szabó et al., 2004). For example, Szabó et al. (2004) measured visual CS in volunteers with and without seasonal affective disorder using static and dynamic sine-wave gratings with spatial frequencies from .5 to 14.4 cycles per degree (cpd) of visual angle. The aim of that study was to investigate the therapeutic effects of light therapy on seasonal depression. The results showed that light therapy sig- nificantly improved visual CS in patients at static spatial fre- quencies below 5.7 cpd. In a pilot study, Cavalcanti e Santos (2005) measured con- trast thresholds in adult volunteers with and without major de- pression under high photopic luminance conditions using non-Cartesian radial visual stimuli at spatial frequencies of .25, 1.0, and 4.0 cpd. The results showed that patients with major depression had a loss of or lower CS for all spatial frequencies compared with volunteers without neuropsychiatric disorders. Wesner & Tan (Wesner & Tan, 2006) measured contrast thresholds in patients with seasonal depression and major de- pression and volunteers without depression using static and dynamic visual stimuli modulated by Gabor’s function with spatial frequencies from .3 to 12 cpd under photopic luminance * Corresponding author.