The top 20 journals in the Scopus database which cite optometry articles are listed in Table 2 in rank order of hOJC-indices, which range from 37 to 154. These top 20 journals can be categorised as: ophthalmology – 11; optometry – 4; vision science – 3; and general science – 2.

The six highest ranking journals in Table 2 are published in the United States. The three highest ranked journals are not optometric; these are Investigative Ophthalmology & Visual Science (hOJC = 154), Ophthalmology (hOJC = 133) and Vision Research (hOJC = 127). The highest performing optometric journal, at rank #4, is Optometry and Vision Science (hOJC = 113), with the other four optometry journals ranking #10, #14 and #16.

The journals that have published the highest number of papers citing optometry articles are: Optometry and Vision Science – 5310 papers; Investigative Ophthalmology & Visual Science – 3139; Ophthalmic and Physiological Optics – 2170; and Clinical and Experimental Optometry – 2080.

The top 10 most impactful papers citing optometry articles are shown in Table 3. These papers have been cited between 2223 and 5725 times. The most highly cited paper referencing optometry articles (5725 citations) is by Terwee et al., entitled ‘Quality criteria were proposed for measurement properties of health status questionnaires’, and published in Journal of Clinical Epidemiology. Only one of the 52 references in this paper was to an article in an optometric journal – Ophthalmic and Physiological Optics.

One of the 10 most impactful papers citing optometry articles presented in Table 3 was published in a vision science journal (The Ocular Surface), one appeared in an ophthalmology journal (Survey of Ophthalmology), and the rest appeared in a diverse array of journals, from the fields of epidemiology, psychology, oncology, allergy, neurology, neurophysiology, and general medicine.

The 20 most impactful authors of papers citing optometry articles are presented in Table 4 and have hOJC-indices ranging from 43 to 69. The academic qualifications of these top 20 authors are: optometrist – 12; ophthalmologist – 4; optical physicist – 2; biostatistician – 1; and microbiologist – 1.

The most impactful author of papers citing optometry articles is ophthalmologist Seang Mei Saw (hOJC = 69). None of the top 4 authors are optometrists; the highest-ranking optometrists are Karla Zadnik (rank #5; hOJC = 53) followed by Lyndon Jones (rank #6, hOJC = 51).

The two most prolific authors of papers citing optometry articles in the top 20 are optometrists Nathan Efron (n = 288 papers) and Lyndon Jones (n = 282). Microbiologist Mark Willcox (n = 256) is at rank #3. The top 20 authors who have published the highest percentage of papers citing optometry articles as a function of their total paper output are optometrists Jason Nichols (80%), Lyndon Jones (79%) and Michael Collins (73%).

Five (25%) of the top 20 most impactful authors of papers citing optometry articles are female: ophthalmologist Seang Mei Saw (hOJC = 69), optometrists Karla Zadnik (hOJC = 53) and Fiona Stapleton (hOJC = 45), biostatistician Gladys Mitchell (hOJC = 45) and optical physicist Susanna Marcos (hOJC = 44).

The top 20 institutions producing papers that cite optometry articles are listed in Table 5. The hOJC-indices of these institutions range from 71 to 127. The top-ranking institution is Harvard University, United States (hOJC = 127), followed by Johns Hopkins University, United States (hOJC = 111) and Moorfields Eye Hospital, United Kingdom (hOJC = 104). Thirteen of the top 20 institutions are home to optometry schools; of these, Ohio State University has the highest ranking (#5) (hOJC = 98). It should be noted that many of these institutions with optometry schools house ophthalmology academic units, which also contribute to these metrics.

UNSW Sydney, Australia, has produced the highest number of papers citing optometry articles (n = 1761), with the University of Melbourne, Australia ranked #2 (n = 1650).

The number of institutions from the various countries represented in Table 5 are: United States – 11; Australia – 5; United Kingdom – 2; Singapore – 1; and Canada – 1.

The 20 most impactful countries producing papers that cite optometry articles are listed in Table 6. The hOJC-indices of the countries listed range from 21 to 313, and the paper count from 1142 to 28,485. The United States is the most impactful and prolific nation producing papers that cite optometry journals (hOJC = 313; n = 28,485) – having a substantially greater hOJC-index, and producing almost three times as many papers, as #2 ranked United Kingdom (hOJC = 200; n = 9788).

It is not surprising that 15 of the top 20 journals (75%) are ophthalmic (i.e., 11 ophthalmology and 4 optometry journals). In any field of research, authors tend to cite papers that in some way support the work that is being reported, which therefore would be primarily derived from the literature base underpinning that field. The authors found 202 non-disambiguated ophthalmology journal names on the Scopus database, compared to 18 disambiguated optometry journal names. Therefore, given the substantial overlap in the subject matter reported by optometry and ophthalmology journals, it is not unexpected that almost three times as many ophthalmology journals cite optometry articles than optometry journals. These citation statistics demonstrate that optometry journals do not exist for the exclusive advancement of optometric science and the optometric profession; optometry journals are also used extensively and valued by ophthalmology researchers, in addition to vision scientists and general medical researchers.

A total of 5310 papers in Optometry and Vision Science have cited optometry articles, which is considerably greater than second-ranked Investigative Ophthalmology & Visual Science (3139 papers). However, optometry article-citing papers published by Optometry and Vision Science (hOJC = 113) are less impactful than those published by Investigative Ophthalmology & Visual Science (hOJC = 154). The likely reason for this is that a substantial proportion of the papers published in Optometry and Vision Science, especially during the first 40 years of publications of that journal (say, 1924 to the 1960s), were editorials, professional commentaries, and clinical material such as case reports – material that tends not to be cited extensively. Conversely, Investigative Ophthalmology & Visual Science was established more recently (1962) as a 'science only' journal, and as such has generally publishes work that is more likely to be cited. The readership of Investigative Ophthalmology & Visual Science is also presumably much larger than that of Optometry and Vision Science.

The broad spectrum of fields reflected amongst the most highly cited papers displayed in Table 3 reinforces the notion that the optometry literature has value far beyond the ophthalmic domain. The 10 leading papers that cite optometry articles are themselves highly impactful, having been cited between 2000 and 6000 times. The impact of such publications can be appreciated when considering that only 0.03% of scientific papers have been cited more than 1000 times.15

Although 82,830 papers are known to have cited optometry articles, only 13.9% of these papers have never been cited themselves, attesting to the overall quality and impact of papers citing optometry articles. The balance of these papers has been cited over 2 million times, further demonstrating the importance of those works, and by extension their value in developing ideas or verifying factual information relating to vision science and beyond.

The most impactful author of publications citing optometry articles is Seang Mei Saw (hOJC = 69), who is professor of ophthalmology at the National University of Singapore. She holds a joint appointment at the Saw Swee Hock School of Public Health, and in that position has conducted several large-scale epidemiologic studies on myopia in children, as principal investigator. Given that the field of refractive error has always been a core area of optometric research and clinical practice,11 Professor Saw would have found it necessary to cite optometry articles extensively to support her writings. As an ophthalmologist, much of her work would be published in ophthalmology journals, which are known to generally have higher impact than optometry journals, hence the high impact of the papers authored by Professor Saw which cite optometry articles. For similar reasons, ophthalmologists Tienyin Wong (hOJC = 60) and Paul Mitchell (hOJC = 54) are ranked #2 and #4.

The last column in Table 4 shows, for each author, the proportion of papers citing optometry articles as a function of all papers published by that author. For the four ophthalmologists listed in this table (Seang Mei Saw, Tienyin Wong, Paul Mitchell and Kazuo Tsubota), none of whom work in university optometry departments, this proportion ranges from 12.4% to 33.0%. For the other 16 authors in Table 4, all of whom work in university optometry departments, the proportion ranges from 45.4% to 79.7%. This observation supports the notion that authors working in a given field are more likely to cite articles from journals relating to that field.

The countries where the top 20 authors have spent most or all of their academic careers are: Australia – 8; USA – 7; UK – 2; Canada – 1; Japan – 1; and Singapore – 1.

The four highest ranking institutions listed in Table 5 are the home of world-renowned ophthalmology departments, hospitals, or eye institutes. Much of the research generated by these institutions, which cites optometry articles, is typically published in high impact ophthalmology journals.

The United States is the leading country for life sciences research,16 which is consistent with this nation producing papers of the highest impact, and the greatest volume of papers, that cite optometry articles.

The volume of the body of papers citing optometry articles (82,830) and the associated measure of impact of these papers (hOJC = 370) can be compared with other disciplines by undertaking crude searches in Scopus. Articles published in dentistry journals been cited by a similar number of papers (80,101) to that of optometry; however, papers citing dentistry articles are less impactful (hOJC = 316) than those of optometry. The body of papers citing articles published in veterinary medicine journals is less extensive (42,208 papers) and less impactful (hOJC = 187) than that for optometry. The higher impact of papers citing optometry articles compared with papers citing dentistry or veterinary medicine articles is not related to the relative size of these professions; for example, there are approximately 165,000 dentists, 120,000 veterinarians and 40,000 optometrists in the United States. Given that citation metrics generally correlate with the size and reach of a discipline,17 the above comparisons could suggest that optometry journals that underpin the practice of optometry are disproportionately more valuable than those supporting dentistry or veterinary science.