Table 1.

Summary of the seasonal trends in the rate and microbiological profiles of infectious keratitis in the literature, in the order of chronology.

Year	Authors	Study period	Sample sizea	Location	Overall seasonal rate	Microbiological profilesb
2008	Green et al. [10]	1999–2004	253	Brisbane, Australia	Not examined	P. aeruginosa (in summer); S. pneumonia (in winter)
2009	Ibrahim et al. [11]	1997–2003	1786	Portsmouth, UK	Summer > winter > autumn > spring	Not examined
2012	Lin et al. [12]	2006–2009	6967	Southeast India	Summer > winter > spring/autumn	Fungi (in summer); P. aeruginosa (in July–December)
2013	Otri et al. [13]	2007–2010	129	Nottingham, UK	Summer > spring > winter > autumn	Not examined
2015	Ni et al. [14]	2009–2012	313	Philadelphia, US	Spring > autumn > summer > winter	Bacteria (in spring)
2016	Gorski et al. [15]	2008–2013	155	New York, US	Summer > winter > spring > autumn	P. aeruginosa (in summer)
2018c	Walkden et al. [16]	2004–2015	4229	Manchester, UK	Winter > autumn > spring > summer	P. aeruginosa (in summer); CoNS (in autumn); Candida (in summer)
2020	Ting et al. (current study)	2008–2019	1272	Nottingham, UK	Summer > autumn > winter > spring	P. aeruginosa (in summer); Gram-positive bacilli (in summer)

^aNumber of cases of infectious keratitis.

^bCausative microorganisms that demonstrated significant seasonal predilection.

^cThe reported seasonal rate refers to the culture positivity rate of infectious keratitis but not the overall rate of infectious keratitis.