Table 1.

List of the 31 studies investigating the microbial contamination of eye drops and their principal features.

Authors	Year of Publication	Country	Study Design	Aim of the Study	Setting
Chantra et al. [17]	2022	Thailand	Cross-sectional study	The aim of this study was to assess the incidence of microbial contamination in preservative-free hospital-prepared anti-infective eye drops and investigate factors that contributed to contamination.	Hospital
Chua et al. [18]	2021	Malaysia	Cross-sectional study	To determine the prevalence of microbial contamination in multi-user preserved ophthalmic drops in an ophthalmology outpatient clinic to compare the rates of contamination between the dropper tip and the residual contents in the bottle and to identify the contaminating organisms.	Hospital
Daehn et al. [21]	2021	Germany		To address the potential contamination of multi-dose ophthalmic solutions in the operating theater and the underlying risk of infection by examining the microbiological load on the tips of dispenser bottles.	Hospital
Kyei et al. [27]	2019	Ghana		To investigate the possible microbial contamination of fluorescein sodium dye solutions used in eye clinics in Ghana.	Eye care clinics
Kyei et al. [28]	2019	Ghana	Cross-sectional study	To determine the microbial contaminants and their clinical importance in topical diagnostic ophthalmic medications in eye clinics in Ghana.	Eye care clinics
Kyei et al. [29]	2019	Ghana	Clinical experiment	To evaluate the microbial contamination of in-use therapeutic ophthalmic medications in the Cape Coast metropolis.	Home
Nisar et al. [35]	2019	Pakistan		To investigate the bacterial contamination of eye drops dispensed for multi-dose purpose.
Tamrat et al. [43]	2019	Ethiopia	Cross-sectional study	To determine the magnitude of contamination and pattern of antimicrobial resistance of in-use ophthalmic solutions.	Hospital
Bachewar et al. [15]	2018	India	Prospective observational study	To determine the magnitude and pattern of microbial contamination rates in multi-dose used eye drop containers and residual medicine in presence or absence of preservatives.	Hospital
Figuêiredo et al. [24]	2018	Brazil	Cross-sectional study	To evaluate contamination in topical medication eye drops of patients from the glaucoma ambulatory of a university hospital and use a questionnaire to analyze the storage and method of instillation of the eye drops collected.	Hospital
Tsegaw et al. [50]	2017	Ethiopia	Cross-sectional study	To assess the magnitude and pattern of bacterial contamination of multi-dose ophthalmic medications and investigate the drug susceptibility pattern of the isolates in the Department of Ophthalmology at Gondar University Teaching Hospital.	Hospital
Teuchner et al. [46]	2015	Austria		To compare the percentage of contamination of multi-use eye drops applied by glaucoma patients at home and by the medical personnel in the outpatient department, ward, and operating room of a Department of Ophthalmology and to test the influence of sampling from the eye drop tips, drops, and residual fluid inside the bottle.	Hospital
Thanathanee et al. [14]	2013	Thailand	Prospective descriptive study	To evaluate the sterility and safety of 100% nonpreserved, autologous, serum eye drop treatment in patients with ocular surface diseases.	Hospital
López-García et al. [12]	2012	Spain	Prospective, consecutive, comparative, and randomized study	To assess the effect of the use of containers with adapted sterilizing filters on the contamination of autologous serum eye drops.	Home
Razooki et al. [39]	2011	Iraq		To determine the magnitude and pattern of microbial contamination of eye drops in outpatients at the department of ophthalmology.	Hospital
Somner et al. [25]	2010	UK		To quantify the financial and waste implications of reducing this risk to zero by using disposable droppers only once.	Eye care clinics
Feghhi et al. [48]	2008	Iran		To investigate the incidence of fungal and bacterial contaminations of in-use eye drop products in the teaching department of ophthalmology.	Hospital
Kim et al. [47]	2008	Republic of Korea	Prospective, non-masked, randomized trial	To evaluate microbial contamination of multiple-use preservative-free artificial tears packed in reclosable containers after daily use.	Home
Nentwich et al. [34]	2007	Kenya	Cross-sectional study	To determine the magnitude and pattern of microbial contamination (bacterial and fungal) of multi-dose ocular solutions.	Hospital
Jokl et al. [22]	2007	USA		To assess the frequency of contamination of ophthalmic solutions in a long-term care facility and to describe the characteristics of contaminated solutions.	Long-term care facility
Rahman et al. [37]	2006	UK		To investigate the incidence of microbial contamination in preservative-free drops dispensed from multi-use containers.	Hospital
Mason et al. [57]	2005	USA	Prospective, non-masked, non-randomized trial	To determine the contamination rate of topical moxifloxacin 0.5% (Vigamox) after clinical use for preoperative and postoperative prophylaxis for cataract surgery.	Hospital
Porges et al. [36]	2004	Israel	Cross-sectional study	To evaluate the sterility of topical glaucoma medications among chronic glaucoma medication users in the community.	Community
Fazeli et al. [23]	2004	Iran		To assess the validity of an increased in-use period for preserved eye drops opened in a hospital outpatient department.	Hospital
Lagnado et al. [13]	2004	UK		To establish if contamination of 20% autologous serum drops prepared under sterile conditions occurred over a 24 h period of one to two hourly use in a hospital inpatient setting.	Hospital
Livingstone et al. [30]	1998	UK	Comparative study	To compare the microbial contamination of eye drop residues used by inpatients for both 7 and 14 days in order to assess the validity of an increased in use period for preserved eye drops issued to hospital inpatients.	Hospital
Clarck et al. [19]	1997	USA		To investigate the possible contamination of a representative sample of diagnostic pharmaceutical agents and irrigating solutions in small office practices.	Eye care clinics
Donzis [56]	1997	USA	Case report	To report a complication of aerosol saline use in a contact lens wearer.	Home
Geyer et al. [49]	1995	USA	Comparative study	To estimate the frequency of contamination of topical antiglaucoma medications used by asymptomatic patients.	Hospital
Schein et al. [41]	1992	USA	Comparative study	To estimate the frequency of medication contamination and to test the hypothesis that contaminated medications were associated with conjunctival colonization with the same organism.	Hospital
Stevens and Matheson [42]	1992	UK		To assess whether short-stay patients having routine surgery who used postoperative eye drops had contamination of these drops on leaving hospital.	Hospital

Abbreviations: UK, United Kingdom; USA, United States of America.