The burgeoning COVID-19 literature

It is 20 months since the dark shadow of the COVID-19 pandemic descended upon the world. The high rates of infection, morbidity and mortality associated with this disease elicited a prompt reaction from health care workers and law-makers in an attempt to restrict the spread of the infection and manage those afflicted. The pharmaceutical industry was also spurred into action, resulting in the development and deployment of effective vaccines within 12 months of the start of the pandemic – a remarkable achievement given that the normal time-course for developing pharmaceutical products can span 5–10 years.

Kinsella et al.¹ have highlighted the exceptional recent progress made in fundamental science, resulting in ‘the fastest’ scientific response to a major infectious disease outbreak or pandemic. In particular, they drew attention to the vital role of the international research community – from the implementation of diagnostics and contact tracing procedures to the collective search for vaccines and antiviral therapies – sustained by unique information sharing efforts.

The primary ‘currency’ of academic advancement is publications in the refereed scientific literature, scrutiny of which can reveal the extent of scientific progress in understanding and dealing with the COVID-19 pandemic. The global academic response in the health care domain has been remarkable, with academic publishers expediting the peer review process and generally making COVID-19-related papers open-access. Helliwell et al.² have confirmed a high degree of editorial responsiveness during the pandemic, with a median submission-to-acceptance time of 5 days, and publisher responsiveness, with a median acceptance-to-publication time of 5 days.² These rapid times-lines come with an important caveat: rapid dissemination of information should not come at the expense of quality, ethical standards or oversight.³

As an example of important contributions of academic journal publishers, Taylor & Francis – the publisher of Clinical and Experimental Optometry – has curated a special collection of COVID-19-related research articles, updated weekly, which provides free access to papers published in all of the medical journals it produces, covering drug discovery, disease treatment and prevention, in order to help advance research discoveries in the fight against COVID-19. There are currently 672 papers in this collection.⁴

The entire COVID-19 literature

To gain an appreciation of the extent of the entire academic literature relating to the COVID-19 pandemic, I searched for ‘COVID’ in the titles, abstracts and key word lists of all papers on the Scopus bibliometric database. This search, conducted on 26 May 2021, revealed a staggering 145,119 papers produced over a 17 month period, which approximates to 285 papers per day. This compares, for example, with the entire field of refractive error (1931–2020)⁵ and all twentieth century publications in the field contact lenses (2001–2020),⁶ which are described by 8881 and 4164 papers, respectively.

The COVID-19 ophthalmic literature

Of particular interest to the readership of this journal is the extent of the COVID-19 literature relating to ophthalmic issues. To determine this, I conducted a crude search – also on 26 May 2021 – of the titles, abstracts and key word lists for all papers on the Scopus database using the following search term:

(TITLE-ABS-KEY (covid) AND TITLE-ABS-KEY (eye) OR TITLE-ABS-KEY (ocular) OR TITLE-ABS-KEY (ophthal*) OR TITLE-ABS-KEY (optom*))

A total of 2084 documents were found, with a combined h-index of 51. These are impressive statistics for a field that has only emerged over a period of 17 months, and almost certainly under-estimate the full body of works, since my crude search would not have captured papers on specific topics such as ‘cataract surgery’ or ‘keratoconus’ that failed to include any of my search terms. Nevertheless, as a comparison, the entire field of orthokeratology, which spans about 50 years, is described by 650 papers and also has a h-index of 51.⁷

The most impactful ophthalmic COVID-19 paper (attracting 786 citations) is a systematic review and meta-analysis by Chu et al.,⁸ published in The Lancet in June 2020, which discusses eye protection (and other measures) to prevent person-to-person transmission of SARS-CoV-2 and COVID-19. The most prolific institution is Moorfields Eye Hospital in the UK, with 43 papers. As might be expected, the USA is the most prolific nation, having produced 473 papers; Australia ranks 9^th with 71 papers. The Indian Journal of Ophthalmology has published the most ophthalmic COVID-19 paper papers (157) of any journal. The most prolific author is Namrata Sharma, Professor of Ophthalmology at the Rajendra Prasad Centre for Ophthalmic Sciences, in New Delhi, India, with 19 papers.

COVID-19 papers in optometry journals

Up until now, 22 papers with the term ‘COVID-19’ appearing in the title, abstract or key words list have been published in optometry journals, as follows: Journal of Optometry (Spain)—7, Ophthalmic and Physiological Optics (UK)—7, Clinical and Experimental Optometry (Australia)—6, and Optometry and Vision Science (USA)—2. The four optometry journals represent 6.7% of the 60 journals that encompass the entire field of optometry, ophthalmology and vision science; however, only 1.1% of the 2084 COVID-19-related ophthalmic papers found in my search have been published in these optometric journal. This statistic suggests that optometry journals are lagging behind in addressing the COVID-19 pandemic, although it should be noted that many non-ophthalmic/vision science journals, such as those covering general medicine, surgery, immunology, microbiology, infectious diseases etc. have also been publishing COVID-19 related ophthalmic papers.

Presenting a COVID-19 focus issue

As a further contribution to the burgeoning COVID-19 ophthalmic literature, this issue of the journal has a special focus on papers related to the COVID-19 pandemic. There are nine contributions, comprising four research papers, two viewpoints, two clinical communications, and this editorial.

Four papers relate to the impact of lockdown during the COVID-19 pandemic. Based on the findings of an extensive survey, Alabdulkader⁹ reported that prolonged use of digital devices significantly increased during lockdown. A concurrent increase in digital eye strain was also observed, leading Alabdulkader to the conclusion that the two are linked. Tzamalis et al.¹⁰ noted a slight increase in the duration of cataract operations, due to greater care being taken when resuming surgery following lockdown. Ghazala et al.¹¹ explained that, during lockdown, live teleophthalmology avoided escalation of referrals to secondary care. An interesting case of microcystic corneal oedema associated with over-wear of decentred orthokeratology lenses during COVID-19 lockdown is presented by Guo et al.¹²

COVID-19-induced retinal changes are discussed in two reports. Oren et al.¹³ used optical coherence tomography to examine 35 patients who had recovered from COVID-19, and found greater central macular thickness and lower ganglion cell layer and inner nuclear layer thickness, compared to healthy control subjects. The authors recommended close monitoring of the retinal layers in the late phase of recovery from COVID-19. Kumar et al.¹⁴ reported a case of COVID-19 induced maculopathy, which presented as a bilateral deposition of fine, yellow, refractile deposits in the foveal centre. These changes were associated with significant vision loss. Oral steroid therapy resulted in a reduction of the foveal deposits and restoration of vision.

Two papers focus on the impact of the COVID-19 pandemic on academic optometry and clinical optometric practice. Schmid et al.¹⁵ provide a snapshot of the adaptations that have been made in the way optometry is taught at Australian and New Zealand universities, employing novel strategies such as synchronous lectures and asynchronous recordings, online storytelling and team-based learning, virtual breakout rooms, videos of optometry techniques, timed on-line assessment and virtual clinical case-studies. The authors conclude that lessons learnt during the pandemic will lead to the future development of these methods, many of which will enhance optometry teaching. Phu et al.¹⁶ discuss how optometric practice has had to adapt to the COVID-19 pandemic, through the prism of early career optometrists. Adopted strategies include a revised approach to optometric triage and co-management, increased use of optometric telehealth, employing contactless delivery of ophthalmic appliances, adopting cleaning protocols, and use of personal protective equipment.

The accelerated time-frame of the academic response to the COVID-19 pandemic is perhaps unprecedented. Further COVID-19 papers are in the pipeline in this journal, and this is undoubtedly the case for other ophthalmic journals and indeed journals of all disciplines. It is especially pleasing to see that the profession of optometry – via its four learned journals published by professional associations in Australia, Spain, the UK and USA – is also contributing to the effort to understand, to cope with, and hopefully eradicate or significantly suppress COVID-19, evidence of which can be found, in part, in this focus issue of Clinical and Experimental Optometry.