title: Development of biomedical publications on ametropia research in PubMed from 1845 to 2010: a bibliometric analysis.
abstract: OBJECTIVE
  We have carried out a bibliometric analysis on the development of ametropia literature to determine its growth rule and tendency, and to provide the basis for the problems related to ametropia research.
  
  
  METHODS
  Literatures that contained the descriptors of ametropia in title or paper published before Nov. 10, 2010 in PubMed databases (www.ncbi.nlm.nih.gov/Pubmed) were selected. As bibliometric indicators of ametropia, biomedical journals referring to ophthalmology by ISSN were calculated. The principal bibliometric indicators: Price's and Bradford's laws were applied on the increase or dispersion of scientific literature, the participation index of languages and the journals. By means of manual coding, literatures were classified according to documents study and statistical analysis.
  
  
  RESULTS
  The literatures cited in ametropia, astigmatism, myopia and hypermetropia had accumulated to 26475, which consists of Review (n=1560), Randomized Controlled Trial (n=776), Practice Guideline (n=10), Meta-Analysis (n=23), Letter (n=1222), Editorial (n=328), Clinical Trial (n=1726) and Others (n=20830), and Humans (n=23073), Animals(n=1434) and others (n=1968). 1136 literatures were included in PubMed Central, 22384 in MEDLINE and 2955 in others. The ametropia literatures rose every 5 years which of the ametropia-year cumulated amount of the literatures had three periods: before 1900, slowly increasing from 1901 to 1950, rapidly rising from 1951 to 2010 (increased approximate exponentiation exponent). Sixty kinds of languages listed in PubMed databases, of which English is dominant for aborting to ametropia research documents before 2010 (77.32%, 20471/26475). The document languages of top eight account for 95.58% (English, German, French, Japanese, Russian, Italian, Spanish, Chinese), and others for 4.42% (1171/26475). The SCI database includes 48 ophthalmologic journals and the impact factor of 39 journals is ≥1 on Thomson-Reuters in 2010. Of 48 ophthalmologic journals, there were 14785 documents (55.85%) of ametropia, astigmatism, myopia, and hypermetropia. Others were without exception.
  
  
  CONCLUSIONS
  The bibliometric analysis results show that ametropia literature are increased progressively, approximate exponentiation exponent during 1951-2010. In addition, ametropia research has become more popular since nearly half century.
authors.affiliation: Department of Anatomy and Editorial Office of Chinese Journal of Neuroanatomy, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China.
authors.forename: Chang-Tai
authors.initials: CT
authors.lastname: Xu
authors.forename: Shan-Qu
authors.initials: SQ
authors.lastname: Li
authors.forename: Yong-Gang
authors.initials: YG
authors.lastname: Lü
authors.forename: Bo-Rong
authors.initials: BR
authors.lastname: Pan