Dandona Lalit, Dandona Rakhi
Health Studies Area, Centre for Human Development, Administrative Staff College of India, Hyderabad, India.
BMC Med. 2006 Mar 16;4:7. doi: 10.1186/1741-7015-4-7.
The existing definitions of visual impairment in the International Statistical Classification of Diseases are based on recommendations made over 30 years ago. New data and knowledge related to visual impairment that have accumulated over this period suggest that these definitions need to be revised.
Three major issues need to be addressed in the revision of these definitions. First, the existing definitions are based on best-corrected visual acuity, which exclude uncorrected refractive error as a cause of visual impairment, leading to substantial underestimation of the total visual impairment burden by about 38%. Second, the cut-off level of visual impairment to define blindness in the International Statistical Classification of Diseases is visual acuity less than 3/60 in the better eye, but with increasing human development the visual acuity requirements are also increasing, suggesting that a level less than 6/60 be used to define blindness. Third, the International Statistical Classification of Diseases uses the term 'low vision' for visual impairment level less than blindness, which causes confusion with the common use of this term for uncorrectable vision requiring aids or rehabilitation, suggesting that alternative terms such as moderate and mild visual impairment would be more appropriate for visual impairment less severe than blindness. We propose a revision of the definitions of visual impairment in the International Statistical Classification of Diseases that addresses these three issues. According to these revised definitions, the number of blind persons in the world defined as presenting visual acuity less than 6/60 in the better eye would be about 57 million as compared with the World Health Organization estimate of 37 million using the existing International Statistical Classification of Diseases definition of best-corrected visual acuity less than 3/60 in the better eye, and the number of persons in the world with moderate visual impairment defined as presenting visual acuity less than 6/18 to 6/60 in the better eye would be about 202 million as compared with the World Health Organization estimate of 124 million persons with low vision defined as best-corrected visual acuity less than 6/18 to 3/60 in the better eye.
Our suggested revision of the visual impairment definitions in the International Statistical Classification of Diseases takes into account advances in the understanding of visual impairment. This revised classification seems more appropriate for estimating and tracking visual impairment in the countries and regions of the world than the existing classification in the International Statistical Classification of Diseases.
《国际疾病分类》中现有的视力损害定义基于30多年前提出的建议。在此期间积累的与视力损害相关的新数据和知识表明，这些定义需要修订。
修订这些定义需要解决三个主要问题。第一，现有的定义基于最佳矫正视力，将未矫正的屈光不正排除在视力损害原因之外，导致对视力损害总负担的大幅低估，约为38%。第二，《国际疾病分类》中定义失明的视力损害临界水平是较好眼的视力低于3/60，但随着人类发展，视力要求也在提高，这表明应使用低于6/60的水平来定义失明。第三，《国际疾病分类》对低于失明的视力损害水平使用“低视力”一词，这与该词在需要辅助器具或康复的不可矫正视力方面的常用含义产生混淆，这表明对于比失明程度较轻的视力损害，使用“中度和轻度视力损害”等替代术语会更合适。我们提议修订《国际疾病分类》中视力损害的定义，以解决这三个问题。根据这些修订后的定义，世界上被定义为较好眼视力低于6/60的盲人数量约为5700万，而世界卫生组织使用现有的《国际疾病分类》中较好眼最佳矫正视力低于3/60的定义估计为3700万；世界上被定义为较好眼视力低于6/18至6/60的中度视力损害者数量约为2.02亿，而世界卫生组织将较好眼最佳矫正视力低于6/18至3/60定义为低视力的估计人数为1.24亿。
我们建议对《国际疾病分类》中的视力损害定义进行修订，考虑到了对视力损害认识的进展。与《国际疾病分类》中的现有分类相比，这种修订后的分类似乎更适合于估计和跟踪世界各国和各地区的视力损害情况。
