Optometry journals have impact

In June each year, journal publishers and academics anxiously await the release of the annual Journal Citation Reports by Clarivate Analytics, which appears on their website Web of Science.¹ These reports include a listing of the impact factor and other metrics for over 21,000 science and social science journals included in the Web of Science Core Collection.

Only journals that demonstrate “high levels of editorial rigor and best practice”, based on 24 quality criteria and four impact criteria, are included.² Although Clarivate has not revealed the specifics of these quality and impact criteria, they are thought to include factors such as being a peer-reviewed publication; having an international editorial board; being published by a recognised publisher; demonstrating long-standing, regular and timely publication of issues; and being leading journals in their field.

Calculating journal impact factor

For any given year, the two-year journal impact factor is the ratio between (a) the number of citations received in that year, for publications in that journal that were published in the two preceding years and (b) the total number of “citable items” published in that journal during the two preceding years.¹ Thus, for example, the 2019 impact factor of a journal is the average number of citations recorded in 2019 to each paper published in that journal in years 2017 and 2018.

Impact factors are of interest because they speak to the ‘importance’ of a journal. A higher impact factor indicates that papers published in a journal are more influential because they are being cited more. A journal containing more highly cited papers is considered to be more impactful.

At the time of writing, the most recent impact factors available are for year 2019, which were released in June 2020; the delay is because these calculations relate to the calendar year, and it takes about six months to undertake all the required calculations, tabulate and publish the results on the Web of Science website.

Optometry journals

Three optometry journals are currently included in the annual impact factor calculations – Clinical and Experimental Optometry, Ophthalmic and Physiological Optics and Optometry and Vision Science. Table 1 details the country of origin, academic publisher, professional association publisher, current (2019) impact factor and ranking of each of these journals. The last of these metrics relates to where the journal is placed on a rank-order list, based on impact factors, of the 60 journals included in the “ophthalmology” category (which includes all ophthalmology, optometry and vision science journals).

Table 1. Optometry journals

Journal	Country	Academic publisher	Professional association publisher	Editor	Impact factor (2019)	Rank
Ophthalmic and Physiological Optics	United Kingdom	Wiley	College of Optometrists	Mark Rosenfield	2.624	18/60
Clinical and Experimental Optometry	Australia	Taylor & Francis	Optometry Australia	Nathan Efron	1.918	34/60
Optometry and Vision Science	United States	Lippincott Williams & Wilkins	American Academy of Optometry	Michael Twa	1.458	40/60

Figure 1 shows trends in impact factors for these three optometry journals over the past five years, as published by Clarivate.¹ Notwithstanding slight variations over time, Ophthalmic and Physiological Optics has maintained the highest impact factor. Clinical and Experimental Optometry has shown a steady increase in impact factor over time, surpassing Optometry and Vision Science in 2019.

Figure 1. Trend in impact factors over the past five years (2015-2019) for the journals Clinical and Experimental Optometry (CXO), Optometry and Vision Science (OVS) and Ophthalmic and Physiological Optics (OPO)

In the context of all 60 journals in the “ophthalmology” category, the three optometry journals could be said to be ‘middle ranking’. The impact factors of journals in this category range from 14.860 (Progress in Retinal and Eye Research) to 0.605 (Klinische Monatsblatter fur Augenheilkunde). The distribution of impact factors in all categories is heavily skewed; in the “ophthalmology” category, only seven of the 60 journals had impact factors > 4.000 in 2019.¹

It is not possible to sensibly compare the impact factors of journals from different categories because this metric is highly influenced by the size of the discipline and variances in other factors such as publication and citation conventions of different disciplines.

It should be noted that other optometry journals do exist, such as Journal of Optometry (Spain); Canadian Journal of Optometry and Clinical and Refractive Optometry (Canada) and Hindsight: Journal of Optometry History (United States). However, none of these journals are currently included in the Web of Science Core Collection.

Striving for higher impact

Given that the magnitude of the impact factor of a journal is an indicator of prestige, a common aim of journal publishers and editors is to elevate their impact factor – hence the keen anticipation surrounding the annual release of the Journal Citation Reports. Key strategies employed to boost impact factors is to publish a higher proportion of review papers, which tend to attract more citations. Since Clarivate only includes full research and review papers with abstracts in the impact factor calculation, publishers also make sure that ancillary forms of communications that generally do not attract high citations – such as editorials, case repots, viewpoints, news items, obituaries and historical notes – do not include abstracts.

It is axiomatic that academics seek to have their published works recognised; accordingly, they generally endeavour to publish their most important papers in journals with higher impact factors. High impact factor journals therefore receive high numbers of submissions, and only publish papers of the highest quality. This results in the better journals publishing better papers, creating an ongoing upward spiral of excellence.

The combined impact of strategic manoeuvring of journal publishers to enhance their impact factor, and the general desire of academics to publish better papers in high impact journals, has resulted in a gradual upward creep of impact factors over time; the median impact factor of all journals for the category “ophthalmology” has increased every year, from 1.124 in 2003 to 1.977 in 2019. In the competitive world of journal publishing, the challenge for all journals is to increase their impact factor at a greater rate than that of others in the same category.

Relevance to optometrists

The three optometry journals listed in the annual Journal Citation Reports clearly have impact, and that is important, because academic journals are the primary repository for the evidence base of the profession, which underpins the very existence of optometry.