The late Dr. John O. Susac described two patients in 1979 (Susac et al., 1979) and then summarized over a hundred cases reported up to 2005 (Susac et al., 2007). The Mayo Clinic reported 29 cases (Mateen et al., 2012) and Dorr et al. reviewed over 300 cases in 2013. Because the syndrome (3:1) favors younger women (aged 20-40 years), includes sudden monocular visual disturbances, multifocal brain damage common in the corpus callosum and symptoms related to the cochlea and semicircular canals, it is easily confused with MS, although it often occurs with headaches, an unlikely symptom in MS but almost always present in Ssac syndrome. In fact, however, Susac syndrome refers to autoimmune microangiopathy rather than an attack on neural elements. Headache, segmental vision loss and ophthalmoscopic signs of retinal arterial occlusion (uncommon in young women) should raise suspicions of Ssac syndrome. The definition of blindness in the Indian National Blindness Control Programme (NPCB) differs from the current World Health Organization definition in the International Classification of Diseases – 10 (ICD-10). The VA criteria according to which a person is classified as blind in the two definitions are different, namely 20/200 in the NPCC definition and 20/400 in the ICD-10 definition after the 2006 revision. In India, the Ministry of Social Justice and Empowerment (MoSJE) is responsible for developing programmes to support persons with disabilities. In a recent initiative, the ministry recommended reducing the blindness review to 20/400 instead of 20/200, which is currently being pursued by the BNPC.
The only difference is that the MoSJE classification is applied to anyone based on the best corrected VA rather than the bidding VA. It is important that the same criteria are generally applied in all programmes related to policy development and service delivery to the blind and partially sighted. Stereopsis refers to the perception of the relative depth or proximity of an object. Determining the exact relationship between vehicles, animals and pedestrians in the driving environment is the most challenging aspect of visual factors. It`s worth bearing in mind that stereo sharpness is not synonymous with depth perception, but is one of many visual cues meant to determine depth. This is tested with TNO and random point stereograms. “Visual impairment” is a term that has sometimes been used to describe visual acuity from 20/70 to 20/200, but it is now commonly used to describe a visual impairment in which the person has usable vision. The development of spatial concepts is also affected by visual impairments. This includes the ability to develop an understanding of where the body is positioned in relation to the classroom environment (is the student at the front, back, or center of the room? What is the distance from teaching objects such as a shelf or the teacher`s desk?) It also affects the understanding of directions such as up, down, right or left when considering space and distance.
