Corneal and Ocular Surface Contributions From Mexico: A Bibliometric Analysis From 1913 to 2022

Objective: This study aimed to investigate all recorded corneal and ocular surface research by Mexican authors. Methods: The output data was extracted from SCOPUS to account for all publications regarding the corneal or ocular surface by Mexican authors. Data screening, extraction, and critical revision were performed by two of the authors to avoid duplication and ensure the authenticity of all papers. Performance analysis, science mapping, and network metrics were employed to retrieve trends in publication. Results: A total of 1,091 indexed journal documents by 3965 authors were retrieved, covering the period the period from 1919 to 2022. In performance analysis, the document types included 881 articles, 20 book chapters, 17 conference papers, three editorials, 37 letters to the editor, nine notes, and 123 reviews. A total of 3,965 contributing authors made 6,081 author appearances. In terms of total citations per country, Mexican authors received a total of 7,087 citations, with an average article citation of 8.76 per author. Conclusion: This bibliometric analysis highlights impactful research contributions to corneal and ocular surface research from Mexican authors, identifies influential authors and institutions, and also emphasizes the need for increased interaction in the international arena.


Introduction
Research is undoubtedly important to a country's scientific development and progress.Biomedical research projects usually lead to publications in serial literature.Original articles allow investigators to present their observations, and the publication of that project allows the information to be shared with the scientific community.Furthermore, publications are often used to measure the success of research work performed by hospitals and institutions.In recent years, there has been growing interest in developing scientific indicators capable of facilitating the analysis of the results of research activities [1].One way of doing so is to perform a bibliometric analysis, which can be regarded as a map of medical research and a study tool using quantitative indicators to understand productivity with characteristics and factors for a greater impact [2,3].The determination of a citation hierarchy list in one specialty of the medical field, formed by numerous journals that are specific to one specialty, allows the discovery of influential authors and institutions as well as opportunity areas.
Work in ophthalmology has grown substantially in the last decades, and research regarding corneal and ocular surface topics has had a special and particular interest due to new modalities of surgery, the uprise of new technology, and cellular biology advances.Previous bibliometric analysis has been performed regarding ocular surface topics such as dry eye disease [2], and others have reviewed Mexican contributions on another topic [3,4].However, no study has been published that addresses the matter of the scientific contribution of a whole country to one specific area of vision science knowledge.This paper will set the pace for the analysis of Mexican authors' contributions to ophthalmology, such as the most studied areas, factors for the impact of publications, characteristics of production, and most productive authors/institutions [3,4].This study aimed to investigate all recorded corneal and ocular surface research by Mexican authors.
No language or year of publication limitation was placed on the articles.Information regarding title, authors, journal of publication, institutional affiliations, year, abstract, and keywords was collected.Data screening, extraction, and critical revision were performed by two of the authors (DJC and BVS) in order to avoid duplication and ensure the authenticity of all papers.Studies were only limited in the query to medicine-related articles.As this study involved the analysis of existing literature without any intervention with human subjects, ethics committee approval was not required.
For a more comprehensive analysis, we recorded variables like temporal profile, research subject, language of publication, type of research, journal of publication, level of evidence, geographic distribution of research output, international collaborations (defined as an article with at least one author having a non-Mexican institutional affiliation, regardless of their nationality), corresponding authors and institutions, and number of citations.
Regarding analysis techniques, performance analysis was performed to rate scientific achievements from different research constituents, science mapping was realized to examine interactions and collaborations among research institutions, and network metrics were used to provide greater clarity of centrality measures [5].
All data was entered into R version 4.0.2(The R Foundation for Statistical Computing, Vienna, Austria), and the "bibliometrix" package was used for data analyses and visual networks [6].Descriptive statistics are expressed with frequencies, percentages, or the mean plus standard deviation, where appropriate.The impact of scientific output was determined by the ratio of citations to publications (c/p) [3].The VOSViewer software version 1.6.18(Centre for Science and Technology Studies, Leiden University, The Netherlands) was used to plot all web network analyses.

Performance analysis
Our analysis retrieved 1,091 documents authored by 3,965 individuals, spanning the years from 1919 to 2022.The document types included 881 articles, 20 book chapters, 17 conference papers, three editorials, 37 letters to the editor, nine notes, 123 reviews (including literature, narrative, systematic/meta-analysis), and one short survey.Among these documents, 49 were single-authored, and 29.06% of the articles involved international co-authorships.The peak year of productivity was 2021. Figure 1 shows the annual scientific production.

FIGURE 1: Density plot showing annual scientific production among Mexican authors
From a total of 6,081 author appearances, they account for 3,965 different contributing authors.The collaboration index was calculated to be 3.63.This is obtained by dividing the number of authors (3,965) by the number of documents (1,091).The dominance factor was also calculated, and the highest-ranked author had a dominance factor of 0.36 [7].

Citation analysis by country
In terms of total citations per country, Mexican authors received a total of 7,087 citations in Mexican journals, with an average article citation of 8.76 per author.Authors from the following countries also cited Mexican authors in their research: the USA, Spain, the UK, the Netherlands, Singapore, Australia, Sweden, India, and Norway.

Science mapping
The most influential papers with at least one Mexican co-author and cited by international authors are summarized in Table 2.
Country collaboration (number of papers with collaborating countries) was strongest between Mexico and the following countries: the USA (80), Spain (17), Italy (7), Singapore (7), the UK (7), Canada (5), Brazil (3), India (3), and the Netherlands (3).The research web of these collaborations is shown in Figure 5. Network analysis between the different authors mentioned previously, showing the collaborations between the most productive groups in the country, is shown in Figure 6.

Discussion
Bibliometric analysis is paramount to elucidating hotspots and knowledge gaps in research, but this method has been applied to Latin American vision science in only a few papers (Ragghianti 2006 [16], Ventura 2008 [17], and Galván 2018 [18]), and those targeting major countries in the region have only been centered in Brazil (Muccioli 2006 [19] and Lira 2013 [20]).Mexico is the largest Spanish-speaking country in the world, the 15th largest economy, and the only Latin American country belonging both to the Organisation for Economic Co-operation and Development and the G20, and bibliometric analysis has only recently been focused on its scientific production as a nation (Paceco Aispuro 2023 [21], Milla 2023 [22]).The Mexican literature in ophthalmology has never been analyzed, and particularly research on corneal diseases that represent of Latin American papers (third subject after retina and strabismus) has never been studied in Latin America.Our paper will address this gap in the existing literature.
The corneal and ocular surfaces constitute one of the most crucial subspecialties in ophthalmological practice and research.In recent years, significant technological advancements have revolutionized the treatment and management of patients with corneal diseases [23,24].These innovations underscore the need for new publications evaluating the safety and repeatability of novel surgical techniques and the application of emerging devices across diverse populations.Approximately 4.5 million people worldwide experience moderate to severe vision impairment due to corneal diseases, while an additional 101.2 million suffer from refractive errors such as myopia, hypermetropia, and astigmatism [25].
Consequently, investigating corneal pathologies and refractive surgery is of paramount importance.
Analyzing the research contributions of a single country in the field of corneal studies can reveal opportunities and unexplored areas for future investigation.Comparing the volume of research from Mexico to that of major research contributors in America, Europe, and Asia can also provide insight into the number of ongoing projects in the country.
Mexican research output (basic and clinical) has surged in the last four decades, as depicted in Figure 1.
Before 1995, only one or two articles were typically published in indexed journals or books.However, the number of published papers experienced a considerable increase after that period, peaking at 86 in 2021.It is plausible that before that date, research was primarily published by local journals or book editors lacking indexation in international databases, leading to an underreporting of the actual volume of research.This trend underscores the significance of international publications for the recognition and dissemination of new knowledge.
Collaboration among Mexican authors has been extensive, as illustrated in Figure 5.Nevertheless, collaboration with international researchers and other countries remains limited, as evidenced by Figure 4.These findings may serve as a catalyst for fostering increased international cooperation in future research endeavors.
Our study does have limitations.Given that the search methodology aimed to encompass as much corneal and ocular surface research as possible, it was challenging to evaluate the impact of these publications on specific diseases, pathologies, or surgical techniques.Nonetheless, we prioritized ensuring that our study remained as inclusive as possible when determining the influence of a particular country on a specific area of research.

Conclusions
Although Mexican contributions to corneal and ocular surfaces have increased significantly, they remain marginal at the global level.Interaction with foreign researchers on this topic remains poor.We have identified the main contributors to the field, and our paper contributes to raising awareness of current collaborations.The mechanisms required to boost our scientific output are complex, and identifying and addressing them is a national health priority that will lead to better medical care and education.Moreover, this will potentially result in economic returns that will compensate for our investments.Future studies should address whether this trend of Mexican research staying at the local level continues, as globalization should help researchers connect and expand knowledge.

FIGURE 2 :
FIGURE 2: Network web plot showing main keyword co-occurrences

FIGURE 5 :FIGURE 6 :
FIGURE 5: Network web plot on country collaboration

TABLE 2 : Papers most cited by international authors
[11]ral and peripheral corneal thickness measured with optical coherence tomography, Scheimpflug imaging, and ultrasound pachymetry in normal, keratoconus-suspect, and post-laser in situ keratomileusis eyes"[11](130, 9.29).Table3shows the papers most cited by other Mexican authors.