Number of times cited (TC) per year after publication for articles selected from the 100 most-cited articles. The number to the left of each article indicates its rank in the citation classics list given in Table 2.
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Ohba N, Nakao K, Isashiki Y, Ohba A. The 100 Most Frequently Cited Articles in Ophthalmology Journals. Arch Ophthalmol. 2007;125(7):952–960. doi:10.1001/archopht.125.7.952
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We screened 46 ophthalmology journals to identify the most frequently cited articles using the Science Citation Index Expanded (1975 to 2006). The 100 most-cited articles were published in 13 journals, most in the Archives of Ophthalmology (n = 30), followed by Ophthalmology (n = 27) and the American Journal of Ophthalmology (n = 11), and originated from 10 countries, led by the United States (n = 86). The topics covered by these classic articles included epidemiology of age-related macular degeneration and glaucoma, description of new diseases including cytomegalovirus retinitis, optical coherence tomography, hypotensive medications in glaucoma, laser photocoagulation to treat diabetic retinopathy and subfoveal choroidal neovascularization, photorefractive surgery, and vitrectomy to treat idiopathic macular hole. The most frequently cited articles provide a historical perspective in the scientific advancement of ophthalmology during the last 3decades.
The number of citations an article receives after its publication reflects its effect on the scientific community.1 Publications in major journals and citations by other researchers are considered when decisions are made about grants, hiring, promotion, and tenure. Analysis of the most frequently cited articles may reveal the effect of works of colleagues and predecessors and provide a historical perspective on the scientific progress in the field of specialty. To our knowledge, this is the first study of the most frequently cited articles published in the last several decades in ophthalmology journals.
We used the Science Citation Index Expanded provided by the ISI Web of Science (Institute for Scientific Information, Thomson Scientific, Philadelphia, Pennsylvania),2 accessed via the Internet (August 30, 2006), to determine the number of citations of articles published in 46 journals dedicated to ophthalmology and its subspecialties. Table 1 gives the 46 journals and the number of original articles and review articles examined; 15 major journals provided articles published from 1975 to the present. The 100 most frequently cited articles were selected to review publishing journal, authorship, institution, country of origin, type of article (epidemiologic study, clinical experience, randomized controlled trial, or basic science), and categories of research topics.
References for the 100 most frequently cited articles published in the last 3 decades in ophthalmology journals are listed in Table 2 according to the number of citations they received, in descending order. These articles have been cited steadily since publication, with a half-life of more than 10 years, as illustrated by a random selection of samples (Figure). The mean number of citations per article is 318. The most-cited article received 684 citations and the least-cited article received 238 citations. These articles were published from 1975 to 2002. The oldest articles were published in 1975, and the most recent article in 2002. Approximately half of the articles were published after 1990.
The 100 most frequently cited articles, or citation classics, in ophthalmology were published in 13 journals (Table 3), most in the Archives of Ophthalmology (n = 30), followed by Ophthalmology (n = 27), the American Journal of Ophthalmology (n = 11), Experimental Eye Research (n = 7), Investigative Ophthalmology and Visual Science (n = 7), and Survey of Ophthalmology (n = 7). The articles were the products of multi-institutional collaboration (n = 8), multinational collaboration (n = 6), and individual institutions (n = 86). For simplicity, in articles from multicenter study groups, the name of the coordinator was defined as the country or institution of origin. The 100 citation classics originated from 10 countries: United States (n = 86), Australia (n = 3), United Kingdom (n = 3), Germany (n = 2), and Canada, Greece,Japan, the Netherlands, Portugal, and Sweden (n = 1 each). The 100 articles were contributed by 41 institutions. Table 4 lists the leading 10 institutions, with 2 publications or more, led by The Johns Hopkins University in Baltimore, Maryland (16 publications), followed by Harvard University in Boston, Massachusetts (8 publications), and the University of Wisconsin in Madison (7 publications).
Fourteen articles were the products of multi-institutional or multinational studies with contributions from as many as 386 participants (Table 2). The remaining 86 articles were products of individual institutions, contributed by 263 authors, ranging from 1 to 12 authors per article (mean number of authors, 4). Table 5 gives the names of 28 authors of 2 or more of the 100 most-cited articles.
Table 6 summarizes the research field and topics covered by the 100 articles. Eleven articles reported epidemiological study results, 67 dealt with clinical experience, and 22 covered basic scienceresearch. Descriptive epidemiology reported the prevalence and risk factors of age-related macular degeneration (n = 2), glaucoma and ocular hypertension (n = 2), diabetic retinopathy (n = 2), and cataract or general blinding diseases (n = 5).
Articles in the clinical experience group were classified into 4 categories. The first category, clinical assessment, dealt with innovation of the visual acuity chart (n = 3); grading or scoring system, or electroretinography test standardization (n = 4); diagnostic imaging technologies including corneal endothelial specular microscopy and optical coherence tomography (n = 4); and retinal nerve fiber layer evaluation (n = 8). In the second category, 11 articles reported new information about clinical diseases including AIDS, idiopathic macular hole, and massive periretinal proliferation. The third category included 14 articles reporting medical therapies for glaucoma and normal-tension glaucoma (n = 8), ganciclovir treatment for cytomegalovirus retinitis (n = 2), and botulinum toxin injection for blepharospasm (n = 2). In the fourth category, 23 articles reported laser and surgical treatments including photodynamic therapy of subfoveal choroidal neovascularization (n = 4), laser correction of refractive errors (n = 6), vitrectomy for idiopathic macular hole (n = 1), trabeculectomy with adjunctive therapy (n = 5), and limbal autograft transplantation (n = 1).
Twenty-two articles were included in the category of basic science with which to achieve understanding of the pathophysiology and pathogenesis of eye disorders. This category included vascular endothelial growth factors, retinal ganglion cell apoptosis, corneal endothelial cell structure and function, and oxygen-induced retinopathy.
Of the 100 citation classics, 12 were products of randomized clinical trials (Table 2), including medications for intraocular pressure control in glaucoma, photodynamic therapy of subfoveal choroidal neovascularization in age-related macular degeneration, treatment of cytomegalovirus retinitis with intraocular sustained-release ganciclovir implantation, vitrectomy for the treatment of postoperative endophthalmitis, and high-dose supplementation with ascorbic acid, vitamin E, beta-carotene, and zinc for age-related macular degeneration. These were multi-institutional or multinational collaborative studies performed in the United States and Europe.
The number of times an article is cited in other articles is widely believed to reflect its effect and the quality of contribution by its authors. Some important articles may not be readily listed as citation classics because their substance has become such common knowledge after publication that their content is no longer cited. Other articles may be frequently cited because they have withstood the test of time. The articles published in the major journals dedicated to ophthalmology and its subspecialties were the target of this citation analysis. The pattern of citations varies among articles and, in the most-cited articles, the number of citations has remained so steady for 10 years or longer that the cumulative number of citations of a given article has increased with time after publication. The 100 citation classics are landmark articles with topics that have inspired clinical and basic research in the past 30 years. As the data show, some of the most important advances include descriptive epidemiology risk factor analysis of diabetic retinopathy, age-related macular degeneration, and glaucoma and ocular hypertension; and diagnostic imaging technologies including optic coherence tomography, laser applications for the treatment of choroidal neovascularization and correction of refractive errors, and vitreous intervention for the treatment of idiopathic macular hole and proliferative diabetic retinopathy.
Most cited classic articles originated in the United States, and only 6 articles originated in non-English-speaking countries. The findings seem consistent with the size of the US ophthalmic community and its wealth and scientific output, which dominate the international ophthalmic publications. There is, however, some evidence that US authors tend to quote articles from US journals and omit relevant references from journals published elsewhere.103 Reviewers from the United States are likely to evaluate papers submitted by US authors more favorably.104
This list of the most-cited articles in ophthalmology identifies seminal contributions and originators, indicates an increasing popularity of randomized clinical trials for acquisition of evidence-based information, and offers ophthalmology researchers hints about what makes an article a most frequently cited classic. To produce such an article, the ophthalmologist and his or her group must offer a medical or surgical innovation, worldwide influential clinical description, or discovery that has a long-lasting effect on the way we practice ophthalmology. Such a contribution should be published in the English language in a major journal.
Correspondence: Norio Ohba, MD, Division of Orthoptics and Visual Science, Aichi Shukutoku University, Faculty of Medical Welfare, Sakuragaoka 23, Chikusa-ku, Nagoya-shi 464-8671, Japan (email@example.com).
Submitted for Publication: November 26, 2006; final revision received November 26, 2006; accepted November 28, 2006.
Financial Disclosure: None reported.