Abstract
Background
Ocular cancer represents a significant threat to vision and life among various eye diseases. Conjunctival melanoma is regarded as one of the most feared and unpredictable ocular tumors. Considering the global differences in the occurrence of ocular melanoma across different races and regions, this study provides a thorough examination of the current state of research pertaining to the epidemiology of ocular and conjunctival cancers.
Methods
This bibliometrics analysis used the Web of Science Core Collection (WoSCC) to collect data from publications on the epidemiology of ocular cancer, including relevant literature from 1951 to 2024. We examined indicators including t publication counts, citation rates, and data on contributing countries, institutions, and journals. Use VOSviewer and CiteSpace for network visualization and Microsoft Excel for data management. Our analysis reveals key trends in the epidemiology of ocular cancer across countries and identifies prominent keywords.
Results
A total of 406 articles on ocular cancer were identified, with significant contributions from the United States, the United Kingdom, and Germany. Denmark also plays a crucial role, particularly in conjunctival cancer research. Carol L. Shields is a leading figure widely recognized for her influential citations in ocular cancer epidemiology. The top publication platforms include the British Journal of Ophthalmology , Ophthalmic Epidemiology , and Ophthalmology . Key terms in ocular cancer research focus on prevalence, survival, and epidemiology, while conjunctival cancer studies emphasize malignant melanoma, conjunctiva, and epidemiology. Through keyword co-occurrence and burst analysis, trending topics include prevalence, risk factors, uveal melanoma, choroidal melanoma, malignant melanoma, squamous cell carcinoma, and conjunctiva. For conjunctival cancer, key research areas expected to remain prominent are cell carcinoma, management, recurrence, ocular surface squamous neoplasia, and pathology.
Conclusions
This analysis represents the first comprehensive bibliometric review mapping the trends and the knowledge structure in ocular cancer research, specifically from an epidemiological viewpoint. The results meticulously explore and encapsulate the research frontiers for scholars dedicated to the epidemiology of conjunctival cancer.
1
Introduction
Unlike other eye diseases, ocular cancer is a distinct one as it endangers vision and life. It is usually diagnosed from a detailed clinical history and specific ophthalmological tests by the treating clinicians. , , The University of Houston outlines the differences between primary malignant and secondary metastatic tumors in other areas or distant locations than those that spread from surrounding tissues. Types of Ocular Tumors Most commonly, Sarcomas, Lymphomas (HL and B cell), Malignant Eyelid Cancer with Basal Cell Carcinoma representing 90%, OSSN including dysplasia, carcinoma in situ SCC, Retinoblastoma, Choroidal Melanoma, Conjunctival melanoma (CoM), and Uveal Melanoma (UM). , , , Among these, ocular melanoma is the most common primary eye cancer in adults, with approximately 83% arising in the uvea, 5% originating intraconjunctivally, and around 10% developing elsewhere in an eye. Conjunctival melanoma, one of the ocular surface tumors accounting for its malignant and aggressive character, scores the highest, with a local recurrence rate close to 50% within ten years after the primary treatment. This malignancy can be locally invasive and spreads systemically via both lymphatic and hematogenous pathways, with a risk for recurrence following treatment.
Northern Europe and Australia have the highest rates, whereas there are lower incidences in Asian, Hispanic, and Black populations of ocular melanoma. It affects predominantly white males and other immunosuppressed individuals. Initial research showed that certain types of melanoma and ocular melanomas, in general, are rare diseases with incidences among white populations, though racial or regional differences may exist. The available literature suggests that ocular melanoma occurs more frequently among Caucasians and less so for other racial groups. ; however, limited numbers of population-based incidence studies have been conducted on occurrence rates in Asian populations.
Bibliometrics is a quantitative study of scientific publications. The total item is Science Bibliometric Studies. Methods like co-word, social network, and cluster analysis were used to get a general perspective of the development trend. Analysis method: Using statistical analysis, authors, journals, and institutions identified key areas and trends. By the co-citation analysis on visualization tools, the bibliometric study creates a knowledge domain map to show research topics and their relations.
Previous bibliometric studies on ocular cancer have mainly focused on tumor treatment, broad cancer categories, or individual tumors, leaving a gap in the epidemiology of ocular tumors. For example, Christophe Boudry et al. (2015) analyzed global trends in eye neoplasms, and Xu et al. (2022) studied conjunctival melanoma; however, neither study delved deeply into tumor incidence patterns. Our study addresses a critical gap in ocular oncology research by analyzing regional disparities in research output and their impact on global trends. We reveal significant variations in research productivity and collaboration patterns across regions, offering a nuanced perspective on the global landscape of ocular tumor epidemiology. This analysis highlights underrepresented areas, emphasizing the need for increased local research and international collaboration. Our comprehensive bibliometric study provides valuable insights for researchers and clinicians in ocular and conjunctival cancer epidemiology by identifying current trends and potential future directions.
2
Material and methods
2.1
Data collection and data retrieval strategy
This cross-sectional study collected publication data on April 17, 2024 and downloaded in “plain text” format from WoSCC.
The retrieved publications had to meet the following criteria.
- (1)
The search terms for total ocular/conjunctival cancer were determined using the TS (“topic”) function, which includes the title, abstract, author keywords, and keywords Plus. The search criteria for the ocular cancer were defined as TS = (ALL= (eye cancer) OR ALL=(ocular melanoma) OR ALL=(ocular neoplasms) OR ALL=(eye tumor) OR ALL=(ocular tumor) OR ALL=(ocular cancer)) AND (ALL=(epidemiology) OR ALL=(incidence rate)); The search criteria for total conjunctival cancer were defined as TS = (ALL=(conjunctival cancer) or ALL=(conjunctival melanoma) or ALL=(conjunctival neoplasms) or ALL=(conjunctival tumor) or ALL=(conjunctival tumor) or ALL=(conjunctival squamous cell carcinoma) or ALL=(ocular surface squamous neoplasia)) AND (ALL=(Epidemiology) or ALL=(incidence rate);
- (2)
the document type was “article”;
- (3)
Unlimited publication period;
- (4)
the following information was collected: publication, authors, countries, institutions, journals, keywords, and citations.
The only difference between the search for articles on ophthalmic tumors and that on conjunctival tumors is the search keywords in the first step; the rest of the steps are the same.
2.2
Data analysis
This study employs bibliometric methods alongside various analytical tools to comprehensively analyze the research field. We extracted bibliographic data from the Web of Science (WOS) database and saved it as a TXT file named “XXX”. The dataset encompasses publication counts, citation frequencies, and information regarding countries, institutions, and journals. The primary visualization tools utilized are VOSviewer (version 1.6.17) and CiteSpace (version 6.3.R2), with Microsoft Excel employed for data processing and chart generation. Excel was used to create charts that illustrate the research performance of top-ranking countries, institutions, authors, and journals. This multidimensional, multi-tool analytical approach enables a comprehensive understanding of the research domain’s developmental dynamics, collaboration patterns, and emerging topics. VOSviewer was employed to extract and process bibliometric data, generating visual maps of country collaboration networks and high-frequency keyword networks. CiteSpace was utilized for visualizing keyword temporal trends and burst detection, with the analysis period spanning from 1951 to 2024, despite the first relevant literature being published in 1996. The time-slicing was set to three years, the Top N threshold was established at 30, and the g-index option set the k value to 25. Citation analysis was performed using the Pathfinder and Pruning sliced networks methods, with the node type designated as keywords. We simplified the network structure by applying the Pathfinder and pruning algorithms to individual and merged networks while maintaining all other parameters at their default settings. This multi-dimensional strategy offers a comprehensive perspective on the evolution and present condition of the field.
3
Results
3.1
Overall publication trends
Quantitative analysis of published papers can help identify the most influential and valuable contributions to the academic community. This information can enhance the quality of scientific literature and guide researchers in their investigative pursuits. Fig. 1 (A and B) illustrates the annual publication output concerning ocular and conjunctival cancer. From the epidemiological literature, 406 articles on ocular cancer were retrieved from 1951 to 2024, while 50 articles on conjunctival tumors were identified from 2003 to 2024. The number of epidemiological articles on ophthalmic tumors from 1951 to 2000 exhibited a relatively slow overall trend, with occasional increases in individual years. However, from 2000 to 2024, a clear growth trend is evident, peaking at 46 articles in 2021, followed by a noticeable decline from 2021 to 2024. In contrast, the volume of epidemiological articles on conjunctival cancer has remained relatively stable from 2003 to 2024, although notable peaks in publications occurred in 2020 and 2021.
3.2
Analysis of published articles by countries/regions and institutions
Ocular cancer is a subject of global significance, as evidenced by the publication of 406 papers across 71 academic journals authored by 2821 researchers from 1021 different institutions in 239 countries and regions, which contributes to epidemiological studies, as shown in Fig. 2 . Fig. 2 highlights global research collaboration in ocular cancer, with high-income countries in North America, Europe, and East Asia leading. The network is divided into five clusters, with three main ones: cluster 1 (red) includes the USA, Canada, and the UK, showing strong collaboration among high-income countries; cluster 2 (blue) consists of China, Japan, and Australia, representing partnerships in East Asia and the Asia-Pacific; and cluster 3 (green) features European countries like Germany and Italy, reflecting close ties within Europe.
Table 1 displays the top 10 countries with the highest research output. Regarding national research capabilities, the USA is at the forefront with 167 publications and 7664 citations, followed by the UK, which has 60 publications and 1988 citations. In comparison, Germany follows with 44 publications and 1051 citations. An examination of collaboration from 1951 to 2024 reveals that the USA boasts the most extensive international partnerships in this area, with the UK maintaining the strongest ties to the USA. Specifically regarding conjunctival cancer, a total of 50 papers published in 21 academic journals were produced by 291 researchers from 228 institutions across 62 different countries and regions. Table 2 enumerates the ten countries with the highest publication totals. A co-authorship network was created for countries and regions with at least one published paper (T = 1) ( Fig. 3 A and B). The visual representation depicts the level of collaboration among these nations and regions, with the USA identified as the largest node within the national network map ( Fig. 3 A). Again, the USA holds the top position in terms of national research output with 17 publications and 539 citations.
| Countries/Regions | Documents | Citations | Total Link Strength |
|---|---|---|---|
| United States | 167 | 7664 | 122 |
| United Kingdom | 60 | 1988 | 133 |
| Germany | 44 | 1051 | 75 |
| China | 37 | 405 | 50 |
| Australia | 27 | 684 | 70 |
| India | 21 | 916 | 56 |
| France | 19 | 821 | 94 |
| Canada | 16 | 320 | 58 |
| Denmark | 16 | 534 | 44 |
| Sweden | 14 | 454 | 50 |
| Countries/Regions | Documents | Citations | Total Link Strength |
|---|---|---|---|
| United States | 17 | 539 | 28 |
| Denmark | 6 | 269 | 21 |
| United Kingdom | 6 | 178 | 32 |
| India | 5 | 60 | 20 |
| Canada | 4 | 95 | 28 |
| France | 4 | 83 | 28 |
| Germany | 4 | 66 | 22 |
| Netherlands | 3 | 211 | 28 |
| South Korea | 3 | 50 | 0 |
| Argentina | 2 | 56 | 28 |
Denmark and the UK each contributed six publications, differing in citation counts (269 and 178, respectively). Moreover, the top 10 most productive institutions are outlined in Table 3 , with Harvard University leading with 16 publications and 1784 citations, followed by Thomas Jefferson University with 14 publications and 1267 citations, and Moorfields Eye Hospital NHS Foundation Trust, which also has 14 publications but 684 citations. When setting a minimum publication threshold for institutions, 46 institutions satisfied the criteria.
| Organization | Documents | Citations | Total Link Strength |
|---|---|---|---|
| Harvard Univ | 16 | 1784 | 14 |
| Thomas Jefferson Univ | 14 | 684 | 32 |
| Moorfields Eye Hosp Nhs Fdn Trust | 14 | 1267 | 5 |
| Thomas Jefferson Univ | 14 | 428 | 14 |
| Univ Melbourne | 13 | 550 | 14 |
| Lv Prasad Eye Inst | 12 | 413 | 26 |
| Ucl | 10 | 635 | 28 |
| Ucl Inst Ophthalmol | 10 | 337 | 16 |
| Univ Copenhagen | 9 | 92 | 7 |
| Harvard Med Sch | 9 | 448 | 27 |
| Univ Cambridge | 9 | 180 | 0 |
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