Introducing a global ranking of optometrists by research impact

I have previously undertaken and published bibliometric analyses documenting the impact of Australia-trained optometrists,^1,2 and have long harboured a desire to extend this to a ranking of optometrists worldwide. This became a reality in September 2020, when I was approached by Professors Jason Nichols (United States), Phil Morgan (United Kingdom), and Lyndon Jones (Canada), to establish an international collaboration aimed at developing such a listing. We agreed to undertake this work, and before long developed a listing of the top 200 optometrists in the world, ranked by h-index (the ‘Top 200’), which is published in this issue.³ This was a substantial undertaking, and our approach is explained in detail in the paper.³

The term ‘bibliometric’ refers to the use of statistical methods to quantitatively analyse a body of published works, such as scientific articles, books, clinical articles, and other forms of scholarly output. The intention of undertaking such analyses is to assess impact in a given field. In health care, the primary metric for determining the impact of an individual is to count the number of scientific papers published (indicating ‘quantity’), and the number of times these papers have been cited (indicating ‘quality’). The ‘gold standard’ measure of the impact of an individual is the h-index⁴ – a single metric that combines quantity and quality. If an individual has an index of ‘h’, the individual has published ‘h’ papers that have been cited at least ‘h’ times. A higher h-index indicates greater impact.

An ongoing, real-time ranking list

The global optometrist top 200 research ranking published in this issue³ is a snapshot in time, captured on 13 January 2021. However, the h-index is not a constant. As time goes on, existing papers continue to accrue citations, and of course academics keep publishing more papers, which will also gather citations over time. This inevitably results in ‘h-index inflation’, which I have shown – in the case of the 10 most impactful Australia-trained optometrists – manifests as an annual increase ranging from 0.6 to 2.7 h-index points.²

An important ramification of this variable h-index inflation is not only the constant state of flux in terms of the various metrics, but (a) changes will occur in the relative rankings of individuals, and (b) names will occasionally enter and leave the listing.

Although the Top 200 listing is the result of exhaustive research and enquiry, and every effort was made to ensure the listing was as complete as possible, it is recognised that inevitably there would be some mistakes and omissions; to identify every impactful optometrist in the world is an onerous task.

To mitigate against the limitations outlined above, the authors of the Top 200 paper have established a ‘companion’ website to host an ongoing, real-time listing. This website (www.optomrankings.com) updates every 24 hours. While the listing published in this issue will remain fixed in time, which was necessary to undertake a full analysis, those accessing the dynamic on-line listing will notice many changes compared with the listing published here, and will continue to notice changes as time goes on.

The website also contains links, in the introductory notes to the listing, which facilitate the nomination of optometrists for inclusion in the listing, and to alert the curators of the website to any other issues requiring rectification. It is hoped and expected that, with the benefit of this anticipated input, the Top 200 listing will evolve and self-correct over time, to become established as a definitive resource for the profession and other interested parties.

Impact of Australian optometrists in an international context

The Top 200 listing allows the impact of leading academic optometrists currently working in Australia to be compared with those in the rest of the world. On 13 January 2001, 43 of the Top 200 optometrists were working in Australia (second only to 76 working in the United States). It is noteworthy that five of the top 10 optometrists were trained in Australia: Konrad Pesudovs (ranked #1), Robert Hess (#2), Gerald Westheimer (#4), Nathan Efron (#7), and Brien Holden (#10).³ Clearly, Australian academic optometry stands tall in the world order.

How will this listing be used?

The Top 200 listing has considerable utility, aside from allowing impactful academic optometrists worldwide to be identified and celebrated. Academic institutions will be able to use this listing to evaluate the impact of academic staff when making new appointments or considering existing staff for promotion, and to benchmark performance against institutional, national and indeed international colleagues. Funding agencies can similarly use the listing to evaluate the impact of research grant applicants.

The leading experts in any field are frequently sought by the lay or professional media for comments on recent developments or issues. The Top 200 listing will assist in the identification of leading research optometrists. This listing will also assist commercial enterprises in identifying leaders in optometric research. Researchers working in other fields seeking interdisciplinary collaborators can use the Top 200 listing to help identify suitable individuals and at the same time gain an appreciation of their international standing.

Many factors are considered, aside from published scientific papers, when professional associations and societies decide upon recipients of research awards and prizes in optometry. These include publication of textbooks and textbook chapters; competitive peer-reviewed research grant income and industry income; patents and inventions; lecture invitations; mentorship of research students and post-doctoral fellows; service to professional and scientific organisations; journal editing and reviewing; and leadership of and/or participation in international scientific workshops and consortia. However, impact of published work is a primary consideration, and the Top 200 listing can provide importance guidance in respect of assessing the research impact of optometric award nominees in an international context.