Discussion of publication status and regularities of distribution of glaucoma articles in the past decade
In this paper, glaucoma and high intraocular pressure are search terms. 2009–2018 is the search span. A total of 19,609 articles were retrieved from SCI, 8489, between 2009–2013, 11120, between 2014–2018. A table shows that from 2009 to 2017, global SCIE publications increased year by year. Yet 2018’s publications’ amount declined compared with 2017. It may be because the search time is March, 2019. Some articles of 2018 have not been included.
The United States, China, and Japan have become the top three countries in the number of articles, leading the development of intercountry glaucoma research. This article focuses on the authors who have published the most articles in the top ten countries and the most cited articles, aiming to explore the teams leading the development of glaucoma research, their outstanding contributions and their primary research areas, providing direction for intercountry cooperation. Professor Weinreb RN from the United States is the first, who has published a total of 325 articles in the past 10 years. The most cited article is Retinal Nerve Fiber Layer Imaging with Spectral-Domain Optical Coherence Tomography A Variability and Diagnostic Performance Study[1], which is quoted as high as 276 times. Professor Weinreb RN notes that spectral-domain OCT shows less variability than time-domain OCT in the measurement of the retinal nerve fiber layer in this article, which suggests the spectral-domain OCT is in more meaningful in assessment of glaucoma progression (by measuring the optic nerve fiber layer thickness).It guides the application of OCT in the assessment of glaucoma progression is with an important clinical significance. Japanese professor ARAIE M has published 117 articles in the past 10 years. The most cited one is Effects of Age, Sex, and Axial Length on the Three-Dimensional Profile of Normal Macular Layer Structures[2], cited 107 times. In this paper, professor ARAIE M points out that the structure of normal macular area is related to age, gender and axial length, suggesting that these factors need to be considered when using the spectral-domain OCT to study the structure of the macular area on patients with retinopathy and glaucoma. It guides the clinical application of OCT and accurate structural measurement. The sixth article from Korean professor team of Eun Ji Lee applies depth imaging technique- spectral domain OCT and the whole thickness of the lamina cribrosa can be clearly visualized. This technology can promote the study of lamina cribrosa in glaucoma patients, and also provide a method for studying the mechanism of optic neuropathy. The seventh article from Indian professor RAO HL finds that the use of RTVueOCT to measure retinal nerve fiber layer and retinal macular thickness can significantly better detect glaucoma visual field defects than the papilla of the optic nerve. These four heavyweight articles thus confirm countries follow the application of OCT in the diagnosis and treatment of glaucoma and glaucoma pathogenesis.
Professor Wang Ningli from China has published 136 articles in the past 10 years. The most cited article is Cerebrospinal Fluid Pressure in Glaucoma A Prospective Study[3], which has been cited for up to 232 times. Professor Wang Ningli firstly discovers that the intracranial pressure of normal-tension glaucoma patient is low and the pressure difference across the lamina cribrosa is high through prospective study, suggesting that the two factors of intraocular pressure and intracranial pressure should be considered in the diagnosis and treatment of glaucoma. The treatment should aim at balancing the pressure gradient of the eye, and the study established the theory of optic nerve damage caused by inadequate pressure gradient of the eye for the first time in the world, which is a milestone.
In epidemiological studies, Professor JONAS JB collects the cause of vision loss in the globe during 1990–2010[4]. In 2010, the world had 65% of blind patients, and 76% of moderate to severe visual impairment patients may have a cause that can be prevented or treated. The causes of blindness vary among patients in different regions, but women worldwide are more likely than men to have blind or moderate to severe visual impairment due to cataracts and macular degeneration. In order to guide public health policy, systematic analysis of the proportion of causes have been ongoing in the past few years, which has a guiding significance for the resource allocation of ophthalmic disease control. The fifth Singapore - India - China cohort study compares the incidence, risk factors and effects of major ophthalmic diseases among Chinese and Indian Malaysian ethnic groups[5]. The study helps to understand the different environmental and genetic impacts of different ethnic groups. In addition, although not in the top ten countries, the Singapore Institute of Ophthalmology published a META study Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis[6], the most cited article in the past decade. This paper systematically analyzes 50 studies data of population-based studies and predicts the number of affected in 2020 and 2040. The study concludes that global prevalence rate of glaucoma in 40–80-year-old people is 3.54%. Highest POAG prevalence is in Africa. Highest PACG prevalence is in Asia. In 2040, the number of glaucoma patients worldwide will increase to 111.8 million. The study is important for the design of glaucoma screening, treatment and related public health strategies.
The ninth and tenth study from Turkish and Italian respectively are related to drug treatment. One proposes that in exfoliation glaucoma, whether the administration is in morning or evening, the group of a fixed combination of bimatoprost and timolol can control 24 hours intraocular pressure better than any group of a single medicine[7]. Another suggests that dithiocarbamates can inhibit carbonic anhydrase activity and exhibit an effect of effectively reducing intraocular pressure in vivo. This new carbonic anhydrase inhibitor provides a new drug candidate for anti-glaucoma drugs[8].
The authors and articles of the above ten countries represent the development of direction of epidemiology, diagnosis and treatment of glaucoma in the past decade. In addition, the top 3 countries that have most articles published are the United States, China and Japan, which accounted for nearly 32.439%, 11.882% and 7.716% of the total number of articles respectively. In the five years before and after the comparison, it can be seen that the number of articles from the United States has declined in the past five years, and the number of articles in several Asian countries has increased significantly, such as China, South Korea, Japan, and India. Among the top 20 authors, the number of authors from Europe and America and authors from Asia is 1:1. And the development in all regions of the world is comparable. Exchanges and cooperation between agencies can promote the progress of science. Before and after the comparison, the frequency of cooperation among authors in the core author group has increased in the past five years, and the frequency of cooperation between Asian countries and Western countries has also increased significantly.
The distribution of fund agencies can show that the authority maintains a leading position: Research to Prevent Blindness (RPB), National Institutes of Health (NIH), National Natural Science Foundation of China, and the National Natural Science Foundation of China has increased its funding for the past five years, leaps to first in the ranking. In the past five years, the number of Japanese funded articles has increased significantly. The agencies are the Japan Ministry of Education, Culture, Sports and Science, Santen, Japan, and the Japan Society for Promotion Science.
Glaucoma research and hotspots analysis
The keyword is the most accurate and concise disclosure of the content of the article. It reflects the main research content of the paper to a large extent and implies the research status, hotspots and development laws of the subject. Based on the author’s keywords, this paper performs statistics after data cleaning and takes the keywords appeared in more than 100 articles, as shown in Table 9. The top three keywords are glaucoma, intraocular pressure and OCT. Build the co-occurrence matrix by the top 50 keywords, on the basis of which we make a co-occurrence map. So, we can visualize the clustering results. The larger the circle in the figure, the larger the number of the article. The thicker the line, and the stronger the correlation between keywords. The keywords of the cross line can be seen as discussion hotspots. It can be seen from Figure 3 that the focus of glaucoma research in the past decade is mainly on: (1) glaucoma and intraocular pressure; (2) glaucoma and OCT; (3) glaucoma and retinal ganglion cells; (4) glaucoma and vision; (5) glaucoma and trabeculectomy and so on. It can be seen that glaucoma-related pathogenesis research, OCT and other imaging examinations in the diagnosis and treatment of glaucoma and glaucoma surgery have attracted much attention. Comparison between the keywords hotspot of before and after five years can reveal that during 2009–2013, the hotspots were CCT, prostaglandin derivatives, indicating the attention on the accuracy of intraocular pressure measurement and prostaglandin anti-glaucoma drugs. During 2014–2018, the hotspots was trabecular meshwork indicating more focus on the function and structure of the trabecular meshwork.
This research belongs to the exploratory research based on published literature, and it has certain limitations. Based on the frequency of keyword occurrence, the research hotspots may miss the latest hotspots. However, it basically conforms to the development law of the international glaucoma field in the past ten years.