Elsevier

The Ocular Surface

Volume 11, Issue 1, January 2013, Pages 35-46
The Ocular Surface

Special Article
Citation Analysis of the Dry Eye Literature

https://doi.org/10.1016/j.jtos.2012.08.004Get rights and content

Abstract

Purpose

The purpose of this study was to characterize the literature associated with the dry eye field.

Methods

An advanced search using Thomson Reuters Web of Science’s Science Citation Index yielded 7,225 unique articles related to dry eye disease. All results underwent visual inspection to ensure that the final list included only literature associated with dry eye in some way. The most frequently cited articles were characterized by number of citations, author, institution, country of origin, year of publication, and source title.

Results

The h-index (Hirsch index) of literature associated with dry eye was 100. The two most frequent topics among the top 25 cited articles were lacrimal gland structure and physiology and treatment methods for ocular surface disease. The top-cited author, institution, country, and source title were Kazuo Tsubota, Harvard University, the United States, and Investigative Ophthalmology and Visual Science, respectively. The most highly cited article associated with the dry eye field (n=1, 180) was “Preliminary criteria for the classification of Sjogrens syndrome – Results of a prospective concerted action supported by the European Community,” authored in 1993 by C. Vitali.

Conclusions

This analysis reviewed the citation frequency of the top-cited articles related to dry eye disease. This information aids understanding of the history and development of dry eye research, in addition to the impact and characteristics of the contributors to the field.

Introduction

Citation analysis is a process that can identify influential publications within a scientific discipline. A citation is simply defined as a reference to the prior work of a scientific author or paper. The author making the citation is acknowledging the influence a past publication has had on interpreting the work that is being reported. A multitude of citations for an author or particular piece of work often signifies its importance and prestige in the scientific community. A highly cited publication could include an innovative hypothesis, compelling observations, discovery of a fundamental or basic mechanism, or sound evidence for a treatment that changes clinical practice.

Trends and themes can emerge from citation analysis that illustrate the path of knowledge in a field of study, the most prolific sources (ie, author, institution, country, source title) of publications, and can objectively list the seminal contributions made in a given scientific field. Citation data can be analyzed using tools such as the Thomson Reuters Web of Science’s Science Citation Index, Web of Knowledge MEDLINE access, or Google Scholar. The Science Citation Index has citation data from over 3,700 scientific journals (1955-present). With such research tools and new metrics, citation analyses have started to permeate many fields of scientific inquiry. Approaches vary by field, but citation analyses generally seek to characterize authors or articles of greatest impact in shaping a field of study.

Citation analysis has become widely used in medical research to evaluate investigators, institutions, countries, and scientific journals. Frequently cited publications can lead to career advancement or research funding. Citation analyses have reported both scientific and general supportive factors associated with high rates of citation. Scientific factors associated with top-cited papers include aspects such as a high level of evidence (ie, study design), a large sample size, or a novel methodology, while supportive factors include publication in a prestigious journal, representation from multiple institutions, authors’ location (eg, geographic or institution), and conflict of interest disclosure.1, 2, 3, 4, 5

One such metric that can be used in citation analysis is the “h-index” (a.k.a, “Hirsch Index” or “Hirsch Number”).6 The h-index was first reported in 2005 by Jorge E. Hirsch, a physicist at University of California San Diego, and it represents an attempt to quantify the productivity and impact of a scholar, group of scholars, scholarly field, journal, institution, or country (although it is most often applied to measuring the impact of scholars). Hirsch describes its calculation as follows: “A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np − h) papers have no more than h citations each.” In other words, to achieve an h-index of 50 (which is quite high), one would need to have 100 papers, of which, 50 had at least 50 citations each (reflecting both the total number of publications and the number of citations per publication). The h-index can be calculated manually or through literature databases, such as the previously mentioned Web of Science’s Science Citation Index, or SCOPUS.

The purported advantage of the h-index, compared with tracking other metrics, such as the total number of publications or total number of citations, is that it more accurately assesses the impact of the subject being studied. For example, a scientist may have a great number of publications, none of which gets cited (suggested low impact); in this situation, the author would have a high publication count but a low h-index. Likewise, a scientist may have a very high number of total citations, driven by a single or few publications, albeit of very high impact; in this situation, the author would have a high citation count but a low h-index. The h-index, while advantageous, does have some shortcomings, including issues such as lack of control of self-citation (although this is more of an issue with counting total citations, as discussed later in this article), lack of reflection of group authorship or author order, and its correlation with age/career span, among other things. Nonetheless, the h-index is a valuable tool when interpreted in context.

The study of dry eye disease has resulted in thousands of publications, and this is likely because of the high prevalence of the disease.7 This body of scientific knowledge has to some degree shaped the current research priorities and provided clinical guidance. Thus, a citation analysis of the “dry eye field” is informative for the dry eye scientific community to realize the strengths and attributes of the current literature and then to identify research needed to advance the field. It is also useful for realizing factors associated with the citation analysis, such as author, geography, institution, or source title.

Section snippets

Database Creation

On May 25, 2012, a citation analysis was conducted using the Thomson Reuters Web of Science’s Science Citation Index-Expanded. Specifically, the following advanced search term was used to identify all literature associated with the dry eye field by topical subject:

TS= (dry AND eye∗ OR dry AND eye AND disease∗ OR keratoconjunctivitis sicca∗ OR therap∗ AND dry AND eye OR sjogren∗ AND dry AND eye OR mcmonnie∗ AND Question∗ OR Laser∗ AND Dry AND Eye∗) OR TI= (tear AND film∗ OR tear AND lipid∗ OR

Results

There were 7,167 articles included in this citation analysis, which were cited a sum total of 103,168 times by 40,889 citing articles (both including self-citations). The distribution of the number of articles by citation frequency is shown in Figure 1. The average citations per item was 14.39 times, and the field had an h-index of 100 (that is, the field had 100 papers each of which had been cited at least 100 times).

The distribution of the 7,167 articles by publication year, beginning in

Discussion

Previously, identifying the most significant publications in dry eye research was somewhat ambiguous because of its subjective nature, but citation analysis can help to objectively identify seminal contributions to the field. The field of dry eye research has an active group of consistent contributors and some prolific sources of publication in terms of author, institution, country, and source title. In a prior citation analysis, Ohba et al conducted a simplified search using the Science

Conclusion

This citation analysis of dry eye literature was able to identify the most highly cited individuals, institutions, and countries. The top-25 cited articles lend a historical perspective to understand the key findings and concepts related to dry eye disease.

References (39)

  • A.H. Filipovich et al.

    National Institutes of Health consensus development project on criteria for clinical trials in chronic graft-versus-host disease: I. Diagnosis and staging working group report

    Biol Blood Marrow Transplant

    (2005)
  • F.J. Holly et al.

    Tear physiology and dry eyes

    Surv Ophthalmol

    (1977)
  • A.P. Simopoulos

    Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases

    Biomed Pharmacother

    (2006)
  • G.N. Foulks

    DEWS Report: A Mission Completed

    Ocul Surf

    (2007)
  • K. Hennessey et al.

    The top 100 cited articles in urology

    Can Urol Assoc J

    (2009)
  • S. Celayir et al.

    The most commonly cited articles in pediatric surgical journals

    Eur J Pediatr Surg

    (2008)
  • R. Paladugu et al.

    One hundred citation classics in general surgical journals

    World J Surg

    (2002)
  • J.E. Hirsch

    An index to quantify an individual’s scientific research outut

    Proc Natl Acad Sci U S A

    (2005)
  • C. Vitali et al.

    Preliminary criteria for the classification of Sjogren's syndrome. Results of a prospective concerted action supported by the European Community

    Arthritis Rheum

    (1993)
  • Cited by (0)

    Grant Support: None

    The author has no proprietary or commercial interests in any concept or product discussed in this article.

    Single-copy reprint requests to Jason J. Nichols, OD, MPH, PhD (address below).

    View full text