As can be seen from Fig. 1, six papers were published on silicone hydrogel contact lenses during the developmental phase in the late 1990s; there was then a sharp increase in the volume of papers, peaking at 76 papers in 2013, and a declining number thereafter. These works have been cited 20,022 times; however, 10.4% of these papers remain uncited. The combined body of work has a hSH-index of 64.

Fig. 1 reveals that the literature on daily disposable contact lenses commenced with five papers published in 1994; this increased to 30 papers in 2020. These papers have been cited 5832 times, with 15.3% of articles uncited. The combined body of work has a hDD--index of 34.

Table 1 lists the top 15 silicone hydrogel contact lens-related papers, ranked by their numbers of citations. Of these, six discuss contact lens-associated keratitis and microbial adherence to epithelial cells (#2, 3, 4, 9, 10 and 14); four report on contact lens deposition and drug release (#5, 6, 7 and 11); three discuss lens polymer structure (#1, 13 and 15); one describes solution-induced corneal staining (#8); and one considers discontinuation from lens wear (#12).

The top 15 daily disposable contact lens-related papers ranked by their numbers of citations are shown in Table 2. Of these, six discuss contact lens-associated infiltrates and keratitis (#2, #3, #4, #6, #8 and #15); two consider lapsed wearers (#5 and #7); two report on contact lens drug release (#9 and #10); two describe non-ulcerative clinical findings relating to lens wear (#11 and #14); and single papers cover advances in contact lens polymers (#1), trends in prescribing contact lenses (#12) and dynamic ocular surface temperature during lens wear.

Six of the top 15 papers in Table 1 (#1, #2, #3, #4, #12 and #14) also appear in Table 2, at ranks (#1, #2, #3, #4, #7 and #8) respectively. The paper ranked #1 in both Tables 1 and 2 is entitled “Soft contact lens polymers: An evolution” by Nicholson and Vogt, that has been cited 495 times. This review paper details the polymeric properties of silicone hydrogel contact lens materials and materials from which daily disposable contact lenses can be fabricated.

Papers #2, #3 and #4 in Tables 1 and 2 (the same papers), as well as the paper ranked #14 in Table 1 and #8 in Table 2, relate to the risk of microbial keratitis of both silicone hydrogel and daily disposable contact lenses, which is a critical consideration when evaluating the safety of these lens types. The paper ranked #12 and #7 in Tables 1 and 2, respectively, considers the impact of silicone hydrogel and daily disposable contact lenses on discontinuation from lens wear, another key consideration in evaluating the success of various contact lens types.

The reason why the papers ranked #2 and #7 in Table 2 each have one more citation than the same paper listed in Table 1 (at ranks #2 and #12, respectively) is because, as stated in the Methods, the analysis of daily disposable papers was conducted six days after the analysis of silicone hydrogel papers, thus allowing more time for additional daily disposable lens citations to accrue.

Table 3 shows the 10 most impactful authors in the field of silicone hydrogel contact lenses, ranked by hSH-index. In this table, the hSH-indices of the authors range from 16 to 33. Lyndon Jones is the most impactful and prolific author by a wide margin, with a hSH-index of 33 and having published 118 papers.

Of the 10 most impactful authors, 9 are optometrists; Mark Willcox (rank #7) is a microbiologist. Two of the top 10 are female – Robin Chalmers and Kathy Dumbleton.

The 10 most impactful authors in the field of daily disposable lenses, ranked by hDD-index are presented in Table 4. In this table, the hDD-indices of the authors range from 7 to 15. Philip Morgan and Nathan Efron are the most impactful authors, each having a hDD-index of 15. Philip Morgan is also the most prolific author, with 35 papers.

Nine of the 10 most impactful authors are optometrists; Thomas Naduvilath at rank #9 is a biostatistician. Four of the top 10 are female – Fiona Stapleton, Robin Chalmers, Kathy Dumbleton and Lisa Keay.

Given that authors with a specialist interest in contact lenses often publish on a multitude of topics within that broad subject area, it is unsurprising that seven of the top authors featured in Table 3 (those ranked #1, #2, #3, #4, #6, #8 and #9) also feature in Table 4, albeit in a different rank order (the corresponding ranks in Table 2 being #3, #10, #2, #1, #6, #4 and #7).

Table 5 lists the 10 most impactful institutions in the field of silicone hydrogel contact lenses ranked by hSH-index. In this table, the hSH-indices of the leading institutions range from 14 to 37. These institutions are based in Australia (2), Canada (2), Portugal (1), Spain (1), the United Kingdom (2) and the United States (2).

The leading institution is the University of Waterloo, with a hSH-index of 37 and a total of 160 papers. Publications have emanated from optometry departments or research centres in 7 of the 10 leading institutions; of the remaining three, one is a research institute (the Brien Holden Vision Institute, rank #3), one is a contact lens company (Alcon Laboratories, #5) and one is an engineering department (at McMaster University, rank #9).

The 10 most impactful institutions in the field of daily disposable contact lenses ranked by hDD-index are listed in Table 6. In this table, the hDD-indices of the leading institutions range from 7 to 16. These institutions are based in Australia (4), United States (3), United Kingdom (2) and Canada (1).

The leading institution is the University of New South Wales, with an hDD-index of 16 (total papers = 28). The University of Manchester has produced the most papers (34). Publications have emanated from optometry departments or optometric research centres in eight of the ten leading institutions; of those listed, the other two institutions are contact lens companies (Johnson & Johnson, ranked #7, and Alcon Laboratories, ranked #9).

For the same reasons as described above in relation to authors, commonality also exists between Tables 5 and 6, whereby seven of the top institutions featured in Table 5 (those ranked #1, #2, #3, #4, #5, #6 and #10) also feature in Table 6, but in a different rank order (the corresponding ranks in Table 2 being #3, #1, #6, #2, #9, #8 and #5).

Academics are peripatetic, often working in different institutions, and in many cases different countries, through their careers. The citation and paper counts presented in this work, in relation to institutions and countries, are those designated by Scopus, and typically relate to the current institution/country of corresponding author of the paper being assessed. This creates two issues: (1) for a paper with a multinational author listing, only the institution/country of the corresponding author is counted; and (2) if an author has previously worked in one or more institutions/countries, these will not be credited, even though the majority of relevant work may have been undertaken there. Accordingly, Tables 5 and 6 should be viewed in light of these factors.

Table 7 lists the top 5 countries contributing to the silicone hydrogel contact lens literature, ranked by hSH-index. The countries range in hSH-index from 22 to 45. The United States is the most impactful and prolific nation, with a hSH-index of 45, and an output of 348 papers.

The top 5 countries contributing to the daily disposable contact lens literature, ranked by hDD-index, are presented in Table 8. Countries range in hDD-index from 7 to 24. The United Kingdom, United States and Australia are equally the three most impactful nations, each with a hDD-index of 24. The United Kingdom is the most prolific country, having produced 91 papers – one more than the United States (90 papers).

The five top counties producing silicone hydrogel and daily disposable contact lenses are common to Tables 7 and 8. The corresponding rankings in Table 8 (to the top five countries featured in Table 7) are #2, #4, #3, #1 and #5.

Table 9 lists the top 5 journals publishing silicone hydrogel contact lens-related papers, ranked by hSH-index. For these journals, the hSH-indices range from 14 to 33. Of the top 5, two are contact lens journals (those ranked #2 and #3), and the other three are optometry (#1), ophthalmology (#4) and vision science (#5) journals. Optometry and Vision Science is the most impactful journal, with a hSH-index of 33, having published 158 papers.

The top 5 journals publishing daily disposable contact lens-related papers, ranked by hDD-index, are shown in Table 10. For these journals, the hDD-indices range from 7 to 17. Two of these top five are contact lens journals (#1 and #3) and three are optometry journals (#2, #4 and #5). Contact Lens and Anterior Eye and Optometry and Vision Science are the most impactful journals, each having a hDD-index of 17. Contact Lens and Anterior Eye has published the most papers (72), by a wide margin from #2-ranked Optometry and Vision Science (46 papers).

Three journals are common to both tables – those ranked #1, #2 and #3 in Table 9, corresponding to ranks #2, #3 and #1 in Table 10. It is unsurprising the two specialist contact lens journals – Eye and Contact Lens and Contact Lens and Anterior Eye – feature in the top three in both tables.