Lubricating drops for contact lens discomfort in adults

Objectives

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To determine the efficacy and safety of lubricating drops for ocular discomfort associated with contact lens wear in adults.

Background

Description of the condition

The Tear Film and Ocular Surface Society (TFOS) has defined contact lens (CL) discomfort as “a condition characterized by episodic or persistent adverse ocular sensations related to lens wear, either with or without visual disturbance, resulting from reduced compatibility between the contact lens and the ocular environment, which can lead to decreased wearing time and discontinuation of contact lens wear” (Nichols 2013). The adverse ocular sensations associated with CL discomfort are increased perception, awareness, and feeling of the CL on the ocular surface, which can include symptoms of dryness, irritation, and foreign body sensation (Chalmers 2006; Nichols 2013; Vajdic 1999). CL discomfort may be accompanied by physical signs, including conjunctival hyperemia, corneal or conjunctival staining, altered blinking patterns, lid wiper epitheliopathy, and probable meibomian glands dysfunction (Efron 2013; Efron 2016; Rueff 2021). A full range of severity can occur with CL discomfort, from mild discomfort to ocular sensations requiring immediate CL removal and sometimes subsequent permanent discontinuation of CL wear (Pucker 2020a). Several factors may contribute to the discomfort sensation through their impact on tear film homeostasis including contact lens material, CL design, fit and wear schedule, contact lens care solution, and environmental factors (Nichols 2013). Hence, CL discomfort is typically classified into two major subclasses, the contact lens (material, design, fit and wear, and lens care) and the environmental factors (inherent or modifiable patient factors, ocular or external environment) (Nichols 2013). These major subclasses potentially contribute to CL discomfort and can impact patients’ quality of life (Dumbleton 2013). Ultimately, the ideal CL has material, design, and care characteristics allowing for optimal fit and wear, vision, and comfort, with minimal patient and environment effects, thereby preventing CL discomfort, promoting ocular health, and improving quality of life. Contact lens discomfort differs from dry eye disease in both signs and symptoms although overlap can occur (Dumbleton 2013). 

Diagnosis of contact lens discomfort

CL discomfort is not synonymous with CL dryness, CL dry eye, or CL‐induced dry eye (Nichols 2013). The latter conditions refer to pre‐existing dry eye disease which is exacerbated by CL wear. Terminology used in the scientific literature published prior to the 2013 Tear Film and Ocular Surface Society’s (TFOS) International Workshop on Contact Lens Discomfort, may have been used interchangeably (Nichols 2013).

A diagnosis of CL discomfort is typically led by patient symptomology. The Contact Lens Dry Eye Questionnaire (CLDEQ)‐8 is a validated questionnaire commonly used in both clinical trials and practice (Chalmers 2012). A cut‐off CLDEQ‐8 score ≥ 12 points indicates a symptomatic CL wearer requiring clinical management and has clinically important difference of 3 points (Chalmers 2016). Another method of measuring the CL comfort is to use a 100‐point numerical visual analog scale, where a change in 7 to 8 points would be considered clinically significant (Papas 2011). Patients experiencing CL discomfort typically report a reduction in comfortable wearing time, followed by a reduction in total wearing time before temporarily or permanently discontinuing CL wear (Nichols 2013); thus, CL wearing time forms a key part in the diagnosis of CL discomfort.

Currently, no clinical signs form a definitive diagnosis of CL discomfort. Studies have reported various signs to be associated with symptomatic CL wear including: lid wiper epitheliopathy, the quality of meibomian gland secretions, tear instability, pre‐lens tear stability, lid parallel conjunctival folds, limbal injection and inferior corneal staining (Stapleton 2021).

Epidemiology of contact lens discomfort

There are approximately 140 million CL wearers worldwide (Nichols 2013); however, the dropout rates reported range from 21.7% (Pucker 2020a) to as high as 51% (Young 2002), thus hindering the growth in the number of CL wearers.

One of the earliest studies to evaluate dry eye disease in CL wearers, the Canadian Dry Eye Epidemiology Study (CANDEES), reported a prevalence of CL‐associated dry eye disease to be 50.1% of respondents who were known CL wearers experienced dryness compared to 21.7% of non‐CL wearers (Doughty 1997). Studies conducted on Chinese office workers reported a prevalence of dryness and discomfort in CL wearers as high as 50.4% (Uchino 2008). In studies conducted on high school students of Asian origin (Japanese and Chinese), the prevalence reported ranged from 32.8% to 37.4% (Uchino 2008a; Zhang 2012).

The prevalence of CL discomfort may vary depending on the method of assessing symptoms and signs, CL discomfort prevalence may also vary with blink pattern, ethnicity, systemic medications and disease, diet, cosmetic use, solution use, and social habits (Nichols 2013). Irrespective of the associated factors, it does appear that CL discomfort undergoes diurnal variation with symptoms worsening towards the end of the day for most CL wearers (Begley 2001).

The literature has been contradictory in terms of sex‐based differences in CL discomfort, while some studies report a higher prevalence of CL discomfort in females compared to males even after controlling for other factors (Nichols 2006), other studies report the difference in the prevalence of CL dryness to be 7% more in females (28% in males) (Uchino 2008). In other large‐scale studies evaluating CL discomfort in 1,054 participants (Chalmers 2006)and 932 participants (Young 2011), respectively, no sex‐based differences in either the frequency or intensity of the contact lens discomfort between males and females were observed.

The TFOS report on CL‐related discomfort states that the evidence from the literature supports some occasional but not entirely consistent patient‐related factors associated with contact lens discomfort, including female sex, younger age, poor tear film quantity and quality, seasonal allergies, and the use of some systemic medications (Dumbleton 2013).

Description of the intervention

The mainstay of treatment for CL discomfort and associated dry eye is the use of over‐the‐counter (OTC) lubricating drops. In accordance with the US Food and Drug Administration (FDA), “in eye solutions” specifically for contact lens discomfort are defined as “rewetting/lubricating drops” (Premarket Notification (510K) Guidance for Contact Lens Care Products) (USFDA 510k Guidance). The FDA also provides a monograph that encompasses "Ophthalmic Drug Products for Over‐The Counter Human Use" which includes topical demulcents and emollients used as “artificial tears” for dry eye (USFDA CFR Part 349). Historically, these artificial tears were not used for CL discomfort as they contained preservatives such as benzalkonium chloride (BAK) that could be adsorbed and absorbed by the contact lenses and then concentrated in the post lens tear film with resultant corneal toxicity (Baudouin 2010). However, the availability of novel preservatives that are “softer” (such as Purite, a stabilized oxychloro complex), single use vials and smart delivery systems that limit microbial overgrowth in artificial tears (Walsh 2019) has contributed to manufacturer marketing and clinical acceptance of the interchangeability of these products for CL discomfort and dry eye (Papas 2013).

The lubricating components of OTC drops include demulcents (such as hypromellose, dextran 70, gelatin and polyethylene glycol (PEG)) and longer retention emollients (such as lanolin, paraffin and mineral oil). More recent formulations have included hyaluronic acid for moisture retention, perfluhexyloctane and omega‐3 fatty acids, to supplement the lipid layer and reduce evaporation (Dogru 2011), and manuka honey (leptospermum) designed to provide dual effects (Hu 2022).

Other interventions to improveCL discomfort and associated dry eye include modification of the local environment, mitigation of topical and systemic drug effects, dietary changes and oral supplementation, lid hygiene and warm compresses, aligning with Stage 1 of Tear Film and Ocular Surface Society DEWS II (Craig 2017). However, compliance is difficult to achieve, and they are often prescribed in combination, meaning as a comparator they are not feasible.

We will include trials comparing OTC lubricating eye drops with (1) placebo that contains only saline or vehicle, or (2) no treatment. 

How the intervention might work

Several studies support improvement of contact lens discomfort symptoms with lubricating drop use; however, as in the treatment of dryness symptoms without contact lenses, this effect is transient (Papas 2013; Pucker 2020b). Clinical signs related to contact lens discomfort, including conjunctival redness, corneal and conjunctival staining, and CL deposits, have also been reported to improve during treatment with lubricating drops (Fernandez‐Jimenez 2022; Pucker 2020b).

Disruption of the tear film has been identified as a key etiology of contact lens discomfort (Craig 2013; Papas 2013). Lubricating drops may improve comfort by mitigating the biophysical and biochemical changes to the tear film associated with CL use. Patients experiencing contact lens discomfort demonstrate decreased stability, increased rate of evaporation, and slower turnover of the tear film (Craig 2013). Higher proportions of immune cells and differential expression of tear proteins including inflammatory cytokines have also been recently described in association with contact lens discomfort (Gad 2019; Nair 2022). Lubricant drops may address CL‐related tear film disequilibria by altering stability, frictional forces, volume, viscosity, osmolarity, temperature, and hydration of the ocular surface environment, including the CL itself (Papas 2013; Pucker 2020b; Stahl 2018). Specific mechanisms of lubricating drops as an intervention in contact lens discomfort are incompletely understood, and remain of interest to clinicians, patients, and the contact lens industry.

Why it is important to do this review

Contact lens discomfort affects over three‐quarters of contact lens wearers (Begley 2001)and is a major contributing factor to contact lens dropout (Nichols 2013). Although there are many potential causes contributing towards the experience of contact lens discomfort or dryness, one common management option adopted by both practitioners and patients is to use OTC lubricating drops. Practitioners and patients have little knowledge of the benefits of lubricating drops in contact lens wearers. Little is known about what type of drop is best for contact lens wearers, whether these drops should be prescribed routinely prior to the onset of symptoms or signs, and what dosage is appropriate. Hence, the need for a synthesis of the evidence.

Objectives

To determine the efficacy and safety of lubricating drops for ocular discomfort associated with contact lens wear in adults.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomized, controlled trials (RCTs) in which individuals were randomized, and both eyes received the same intervention. We will also include RCTs that randomized participants' both eyes to the same intervention but reported eye‐specific outcome data. We will categorize these trials as cluster‐RCTs if the authors accounted for within‐person correlation of the data reported. We will also include paired‐eye design RCTs (both eyes randomized to different treatment) given that the treatment only has a local effect. We will not include cross‐over clinical trials in this review. We will include eligible studies regardless of their publication status, language, or year of publication.

Types of participants

We will include trials of adult participants, age 18 and over, with discomfort or irritation related to contact lens use as defined by the trial investigators. We will also include trials in which the age of participants is not reported. No restrictions will be placed on the duration of lens wear experience (i.e. number of years of prior contact lens wear). We will consider studies that used any types of contact lens materials. We will include studies that involved participants of any race, ethnicity, sex or gender, prior ocular or systemic health condition, or contact lens experiences. We will exclude studies in which only a subset of participants is relevant.

Types of interventions

We will include trials comparing OTC lubricating eye drops with (1) placebo that contains only saline or vehicle, or (2) no treatment. We will exclude studies that use lubricating ointment, gel, or other non‐ophthalmic solution formula. We will include eligible trials regardless of dosing regimens. We will exclude trials that assess the effects of combination interventions that include OTC lubricating drop with another topical (e.g. steroid), systemic (e.g. omega‐3 fatty acid), or behavioral (e.g. warm compression) intervention, except for trials that apply non‐lubricating co‐interventions to all comparison groups as part of the standard care.

Types of outcome measures

We will consider all eligible studies regardless of the availability of the outcome data.

Critical outcomes

Mean changes in participant‐reported contact lens discomfort, using a validated questionnaire at one to four weeks of follow‐up. We will consider outcome data at the longest follow‐up time point up to four weeks as reported by the included trials.

The timeline of one to four weeks has been selected as this is typically used in clinical practice where eye care practitioners prescribe lubricant drops and follow‐up patients within four weeks. Any symptom improvements among contact lens wearers would be anticipated within this timeframe and likely plateau thereafter since lubricant drops do not have an active pharmacological agent. Further, most studies involving lubricating drops in symptomatic contact lens wearers also use one month as the treatment duration (Pucker 2020b).

Important outcomes

The important outcomes of this review will include objective physical examinations, as described below.

• Mean change in corneal fluorescein staining scores from baseline to the longest follow‐up time between one and four weeks as reported by the included studies.

• Mean change in conjunctival redness scores, overall scores or scores of any specific quadrant as reported by the included studies, preferably nasal and temporal quadrants as they are exposed to the environment and have more interaction with the lids, from baseline to the longest follow‐up time between one and four weeks.

• Adverse outcomes as reported at the end of the trials, including:

  • proportion of eyes or participants with incident microbial keratitis;

  • proportion of eyes or participants with one or more inflammatory corneal infiltrates, visible by slit lamp examination; and

  • proportion of participants who discontinued use of CL or rates of CL‐related dropouts.

Search methods for identification of studies

Electronic searches

We will search the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (latest issue), Ovid MEDLINE, Ovid MEDLINE E‐pub Ahead of Print, Ovid MEDLINE In‐Process and Other Non‐Indexed Citations, Ovid MEDLINE Daily (January 1946 to present), Embase (January 1947 to present), PubMed (1946 to present), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to present), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We will not use any date or language restrictions in the electronic search for trials.

See: Appendices for details of search strategies for CENTRAL (Appendix 1), MEDLINE (Appendix 2), Embase (Appendix 3), PubMed (Appendix 4), LILACS (Appendix 5), ClinicalTrials.gov (Appendix 6) and the ICTRP (Appendix 7).

Searching other resources

We will also search reference lists of the trials included in this review to identify additional potentially relevant trials. We will also contact authors for information clarification, missing data and for updated information of eligible yet ongoing trials.

Data collection and analysis

Selection of studies

The Information Specialist will provide separate search results from electronic databases and trial registries. We will import these search results into web‐based software, Covidence, to screen for eligible studies and collect data. After Covidence automatically removes duplicate citations, two review authors will independently screen the titles and abstracts of all records identified through the searches. Each review author will classify each study as "yes (relevant)", "maybe (potentially relevant)", or "no (definitely not relevant)." We will then retrieve full‐text reports of the studies assessed as relevant or potentially relevant. Two review authors will independently assess the eligibility for inclusion of the full‐text reports and classify each as 'include' or 'exclude' We will resolve any discrepancies through discussion, and a third review author will adjudicate on the assessments when discrepancies are not resolved. One review author will also contact trial investigators for additional clarification when studies are assessed as unclear. We will report studies excluded after full‐text assessment in the 'Characteristics of excluded studies' table, with reasons for exclusion. The unit of interest for the review will be the study, and we will list multiple reports of the same study under a single study ID. We will record the study selection process in detail in order to complete a PRISMA flow diagram (PRISMA 2020).

Data extraction and management

Two review authors will independently extract pertinent trial‐level characteristics, including descriptions of the participant sample, study design, treatment comparisons, and treatment outcomes from the included trials using data extraction forms developed by Cochrane Eyes and Vision US Project (CEV@US) in Covidence. We will consider collecting the following items whenever available.

• Methods: study design, total duration of study, number of study centers and location, study setting, and date of study, how eyes were handled in the design and analysis of the primary study. If one eye per person how was that eye selected; if both included how were they analyzed to account for data dependence.

• Participants: number (people/eyes) randomized, number lost to follow‐up/withdrawn, number analyzed mean age, age range, sex, severity of condition, diagnostic criteria, inclusion criteria and exclusion criteria.

• Interventions: intervention, comparison, concomitant medications (or co‐intervention) and excluded medication. For multi‐arm studies, we will extract only relevant data from eligible intervention and comparator treatments.

• Outcomes: outcomes specified and collected, and time points recorded.

• Information about funding for the trial, notable conflicts of interest of the trial authors, trial registration ID, and date of trial registration.

We will resolve discrepancies through discussion. One review author will attempt to contact investigators of included trials for missing data or clarification of trial information, with a period of two weeks for the trial investigators to respond. One review author will enter data into RevMan Web and a second review author will confirm all entries.

Assessment of risk of bias in included studies

We will use the RoB2 tool to assess risk of bias in the reported results of the critical outcome—patient‐reported discomfort—at the longest point between week one to four as guided by the RoB2 signaling questions in the following five bias domains in the RoB2 tool (Higgins 2022a):

• bias arising from the randomization process;

• bias arising from deviations from intended interventions;

• bias arising from missing outcome data;

• bias in measurements of the outcome; and

• bias in selection of the reported result.

In particular, we will be interested in assessing effects of intervention assignment, rather than intervention adherence. For each included trial reporting the outcome, two review authors will independently judge each domain as low, high, or some concern with documentation to support the review authors’ judgment (Sterne 2019). We will use the RoB2 Excel tool to implement the assessment and documentation process (Higgins 2022a). One review author will attempt to contact the primary trial investigator if there was insufficient information to determine the risk of bias. We will resolve discrepancies through discussion or adjudication by a third review author.

For other review outcomes, those defined as important rather than critical outcomes, we will apply the previous tool (RoB1) to assess study‐level risk of bias as guided by the corresponding signaling questions in the following domains (Higgins 2011):

• bias arising from the randomization process;

• bias arising from the allocation concealment;

• bias associated with not blinding (masking) of participants and personnel;

• bias associated with not blinding (masking) outcome assessment;

• bias arising from incomplete outcome data;

• bias in selective reporting; and

• other sources of bias.

We will also use a variant version of the RoB2 Excel tool to evaluate risk of bias in the reported cluster‐randomized trials. We will evaluate the following domains in cluster‐randomized trials:

• bias arising from the randomization process;

• bias arising from the timing of identification and recruitment of participants;

• bias due to deviations from intended interventions;

• bias due to missing outcome data;

• bias in measurement of the outcome; and

• bias in selection of the reported result.

Measures of treatment effect

We will summarize continuous data by calculating mean differences (MD) with standard deviations (SDs) between the treatment and the comparison arms or median with interquartile range (IQR) as reported by the included studies (Higgins 2022c). We will derive SD using methods suggested in the Handbook when the primary studies report 95% confidence intervals (CIs) instead of SD (Higgins 2022c). When the included studies do not report change scores (differences from the baseline) but only endpoint values at the last study visit, we will use the post‐intervention endpoint values for each comparison group to estimate the treatment effect as recommended in the Handbook (Higgins 2022c). 

We will calculate standardized mean differences (SMD) for patient‐reported discomfort scores measured by different symptom questionnaires. We will interpret treatment effects expressed in units of SMD following the rule of thumb as suggested by Cohen, which considers an SMD of 0.2 a small effect, 0.5 a moderate effect, and 0.8 a large effect (Cohen 1988). For discomfort scores measured by the same instrument but in different interval scales, we will transform the symptom scores to a common scale with the fewest incremental units. We will calculate summary risk ratios (RRs) and 95% CIs for dichotomous outcomes (Higgins 2022c).

Unit of analysis issues

The unit of analysis in this review will be an individual participant who was randomized to each treatment arm, because contact lens discomforts are usually a bilateral condition. When both eyes of a single participant are randomized to one treatment and each eye of a single participant is included in the analyses separately for evaluating eye‐specific outcomes, the review authors will classify the trial as a cluster‐randomized trial. We plan to include such a trial design in analysis by applying additional methods described in Chapter 23 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2022b), but only when intra‐person correlation was considered in analyses of the primary study. For trials that randomized and analyzed at the eye level without properly addressing the intra‐person correlation, we will include these studies only in the qualitative synthesis.

For trials of paired‐eye design, we will include them only in the qualitative synthesis when the authors did not analyze or report between‐eye intervention effects correctly.

Dealing with missing data

We will attempt to contact investigators of included trials for clarification of eligibility criteria, for inclusion for assessing risk of bias, and for missing trial outcome data. We will extract available data from the published papers or from the results section on the trial registry website whenever trial authors are unable to provide requested information or did not respond after a period of two weeks. We will use imputed data if computed by the trial investigators using suitable statistical methods; we will not impute missing data ourselves.

Assessment of heterogeneity

We will assess clinical and methodological heterogeneity by examining characteristics of trial participants, treatment/control comparisons, and assessment of trial outcomes. We will examine the amount of consistency across trials as qualified by the I² statistic and by inspection of forest plots to determine the presence of heterogeneity. In accordance with Chapter 10 of the Handbook, we will interpret an I² statistic value by the following thresholds (Deeks 2022):

• 0% to 40% might not be important;

• 30% to 60% may represent moderate heterogeneity;

• 50% to 90% may represent substantial heterogeneity; and

• 75% to 100% considerable heterogeneity.

In cases where we judge that there is considerable heterogeneity we will not report a pooled estimate. In addition, we will not present a pooled estimate when we detect clinical or methodological heterogeneity from the details shown in the 'Characteristics of included studies' table. Instead, we will report a narrative or tabulated summary of the included trials.

Assessment of reporting biases

We will assess selective result reporting for ocular symptoms guided by the signaling questions in the RoB2 tool (Higgins 2022a). We will assess selective outcome reporting for each study using methods outlined in Chapter 13 of the Cochrane Handbook for Systematic Reviews of Interventions (Page 2022). We will assess small‐study effects, which could be due to publication bias, using a funnel plot when 10 or more studies contribute data to a meta‐analysis (Egger 1997).

Data synthesis

In addition to a narrative summary of the included trials, we will conduct meta‐analysis when we decide that there is no considerable clinical or methodological heterogeneity, due to variability in interventions, measurements taken, and follow‐up intervals for the outcomes of interest. When a meta‐analysis includes fewer than three trials, we will use a fixed‐effect model; otherwise we will use a random‐effects model (Deeks 2022). We will include all eligible studies in the primary analysis and then perform sensitivity analysis to verify the robustness of the results by excluding studied with an overall high risk of bias (see Sensitivity analysis).

Subgroup analysis and investigation of heterogeneity

To investigate potential sources of heterogeneity, we will conduct subgroup analysis on changes in symptom scores at post‐treatment week 1 to 4, by the following factors, depending on the availability of data:

• materials of CL (e.g. soft lens versus rigid gas‐permeable lenses); and

• wearing schedule (e.g. daily disposable versus weekly or monthly lenses).

Sensitivity analysis

To assess the robustness of the effect estimates, we will re‐run meta‐analyses on the critical outcome by excluding studies with an overall high risk of bias.

Summary of findings and assessment of the certainty of the evidence

We will prepare summary of findings tables for the following two outcomes.

1. Change in patient‐reported symptom scores at the longest follow‐up time between one and four weeks.

2. Proportion of participants who discontinued use of CL during the trial period.

Two review authors will independently GRADE the certainty of evidence for each outcome (including critical and important outcomes) using the GRADE classification (Schünemann 2022). For each outcome, we will GRADE the certainty of evidence as high, moderate, low, or very low using the following criteria to downgrade the assessment:

• an overall high or some concerns risk of bias among included trials;

• indirectness of evidence;

• unexplained heterogeneity or inconsistency of results;

• imprecision of results (i.e. wide confidence intervals); and

• high probability of publication bias (based on results of RoB2 or RoB1 assessment).

We will resolve discrepancies by discussion to achieve consensus within the review author team.

Appendices

Appendix 1. CENTRAL search strategy

#1 MeSH descriptor: [Contact Lenses] explode all trees
#2 ((contact or contacts) NEXT/2 (lens or lenses)):ab,ti,kw
#3 ((hydrogel* or hydrophilic* or silicone* or "gas permeable" or "gas permeables") NEXT/2 (contact or contacts)):ab,ti,kw
#4 ((hydrogel* or hydrophilic* or silicone* or "gas permeable" or "gas permeables") NEXT/2 (lens or lenses)):ab,ti,kw
#5 ((soft or disposable or disposables or daily or dailies or monthly or monthlies or weekly or weeklies or "extended wear" or "continuous wear" or hybrid* or biweek* or replacement*) NEXT/2 (contact or contacts)):ab,ti,kw
#6 ((soft or disposable or disposables or daily or dailies or monthly or monthlies or weekly or weeklies or "extended wear" or "continuous wear" or hybrid* or biweek* or replacement*) NEXT/2 (lens or lenses)):ab,ti,kw
#7 {OR #1‐#6}
#8 MeSH descriptor: [Nonprescription Drugs] explode all trees
#9 ("over‐the‐counter" or "over the counter" or OTC)
#10 ("non‐prescription" or "non‐prescriptions" or "non prescription" or "non prescriptions" or nonprescription*)
#11 MeSH descriptor: [Ophthalmic Solutions] explode all trees
#12 ("artificial tear" or "artificial tears" or "tear substitute" or "tear substitutes" or eyedrop*)
#13 ((eye or eyes or ocular* or ophthalmic* or "non prescriptive" or nonprescriptive* or wetting or rewetting or lubricating) adj2 (drop or drops or agent or agents or solution or solutions))
#14 MeSH descriptor: [Ointments] explode all trees
#15 (ointment* or lubricant*)
#16 MeSH descriptor: [Demulcents] explode all trees
#17 demulcent*
#18 MeSH descriptor: [Hypromellose Derivatives] explode all trees
#19 MeSH descriptor: [Methylcellulose] explode all trees
#20 (hypromellose or "cellulose derivative" or "cellulose derivatives" or "carboxymethylcellulose sodium" or CMC or hydroxypropylmethylcellulose or "hydroxypropyl methylcellulose" or HPMC or "hydroxyethyl cellulose" or methylcellulose or methoxyhydroxypropylcellulose or carbomer* or cellulose)
#21 "dextran 70"
#22 MeSH descriptor: [Gelatin] explode all trees
#23 (gelatin* or "HP Guar" or "Carbopol type gel")
#24 MeSH descriptor: [Polyethylene Glycols] explode all trees
#25 ("liquid polyol" or "liquid polyols" or glycerin* or "polyethylene glycol" or "polyethylene glycols" or "PEG 300" or "PEG 400" or "polysorbate 80" or "propylene glycol" or "propylene glycols" or "polyhydric alcohol" or "polyhydric alcohols").tw.
#26 MeSH descriptor: [Polyvinyls] explode all trees
#27 ("polyvinyl alcohol" or "polyvinyl alcohols" or polyvinylalcohol* or PVA)
#28 (povidone or polyvinylpyrrolidone)
#29 MeSH descriptor: [Hyaluronic Acid] explode all trees
#30 "sodium hyaluronate"
#31 MeSH descriptor: [Emollients] explode all trees
#32 emollient*
#33 MeSH descriptor: [Lanolin] explode all trees
#34 MeSH descriptor: [Paraffin] explode all trees
#35 MeSH descriptor: [Mineral Oil] explode all trees
#36 MeSH descriptor: [Fatty Acids, Omega‐3] explode all trees
#37 MeSH descriptor: [Leptospermum] explode all trees
#38 (lanolin* or paraffin*)
#39 ((castor or mineral) NEXT/2 oil*)
#40 ("omega‐3" or "omega 3")
#41 (manuka or leptospermum)
#42 {OR #8‐#41}
#43 #7 AND #42 in Trials

Appendix 2. MEDLINE (Ovid) search strategy

1. Randomized Controlled Trial.pt.
2. Controlled Clinical Trial.pt.
3. (randomized or randomised).ab,ti.
4. placebo.ab,ti.
5. drug therapy.fs.
6. randomly.ab,ti.
7. trial.ab,ti.
8. groups.ab,ti.
9. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8
10. exp animals/ not humans.sh.
11. 9 not 10 
12. exp Contact Lenses/
13. ((contact or contacts) adj2 (lens or lenses)).tw.
14. ((hydrogel* or hydrophilic* or silicone* or "gas perm*") adj2 (contact or contacts)).tw.
15. ((hydrogel* or hydrophilic* or silicone or "gas perm*") adj2 (lens or lenses)).tw.
16. ((soft or disposable or disposables or daily or dailies or monthly or monthlies or weekly or weeklies or "extended wear" or "continuous wear" or hybrid* or biweek* or replacement*) adj2 (contact or contacts)).tw.
17. ((soft or disposable or disposables or daily or dailies or monthly or monthlies or weekly or weeklies or "extended wear" or "continuous wear" or hybrid* or biweek* or replacement*) adj2 (lens or lenses)).tw.
18. or/12‐17
19. exp Nonprescription Drugs/
20. ("over‐the‐counter" or "over the counter" or OTC).tw.
21. ("non‐prescription*" or "non prescription*" or "nonprescription*").tw.
22. exp Ophthalmic Solutions/
23. ("artificial tear*" or "tear substitute*" or eyedrop*).tw.
24. ((eye or eyes or ocular* or ophthalmic* or "non prescripti*" or nonprescripti* or wetting or rewetting or lubricating) adj2 (drop or drops or agent or agents or solution or solutions)).tw.
25. exp Ointments/
26. (ointment* or lubricant*).tw.
27. exp Demulcents/
28. demulcent*.tw.
29. exp Hypromellose Derivatives/
30. exp Methylcellulose/
31. (hypromellose or "cellulose derivative*" or "carboxymethylcellulose sodium" or CMC or hydroxypropylmethylcellulose or "hydroxypropyl methylcellulose" or HPMC or "hydroxyethyl cellulose" or methylcellulose or methoxyhydroxypropylcellulose or carbomer* or cellulose).tw.
32. "dextran 70".tw.
33. exp Gelatin/
34. (gelatin* or "HP Guar" or "Carbopol type gel").tw.
35. exp Polyethylene Glycols/
36. ("liquid polyol*" or glycerin* or "polyethylene glycol*" or "PEG 300" or "PEG 400" or "polysorbate 80" or "propylene glycol*" or "polyhydric alcohol*").tw.
37. exp Polyvinyls/
38. ("polyvinyl alcohol*" or polyvinylalcohol* or PVA).tw.
39. (povidone or polyvinylpyrrolidone).tw.
40. exp Hyaluronic Acid/
41. "sodium hyaluronate".tw.
42. exp Emollients/
43. emollient*.tw.
44. exp Lanolin/
45. exp Paraffin/
46. exp Mineral Oil/
47. exp Fatty Acids, Omega‐3/
48. exp Leptospermum/
49. (lanolin* or paraffin*).tw.
50. ((castor or mineral) adj2 oil*).tw.
51. (omega‐3 or omega 3).tw.
52. (manuka or leptospermum).tw.
53. or/19‐52
54. 18 and 53
55. 11 and 54

The search filter for trials at the beginning of the MEDLINE strategy is from the published paper by Glanville et al (Glanville 2006).

Appendix 3. Embase.com search strategy

#1 'randomized controlled trial'/exp
#2 'randomization'/exp
#3 'double blind procedure'/exp
#4 'single blind procedure'/exp
#5 random*:ab,ti
#6 #1 OR #2 OR #3 OR #4 OR #5
#7 'animal'/exp OR 'animal experiment'/exp
#8 'human'/exp
#9 #7 AND #8
#10 #7 NOT #9
#11 #6 NOT #10
#12 'clinical trial'/exp
#13 (clin* NEAR/3 trial*):ab,ti
#14 ((singl* OR doubl* OR trebl* OR tripl*) NEAR/3 (blind* OR mask*)):ab,ti
#15 'placebo'/exp
#16 placebo*:ab,ti
#17 random*:ab,ti
#18 'experimental design'/exp
#19 'crossover procedure'/exp
#20 'control group'/exp
#21 'latin square design'/exp
#22 #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 OR #21
#23 #22 NOT #10
#24 #23 NOT #11
#25 'comparative study'/exp
#26 'evaluation'/exp
#27 'prospective study'/exp
#28 control*:ab,ti OR prospectiv*:ab,ti OR volunteer*:ab,ti
#29 #25 OR #26 OR #27 OR #28
#30 #29 NOT #10
#31 #30 NOT (#11 OR #23)
#32 #11 OR #24 OR #31
#33 'contact lens'/exp
#34 ((contact OR contacts) NEXT/2 (lens OR lenses)):ab,ti,kw
#35 ((hydrogel* OR hydrophilic* OR silicone* OR 'gas perm*') NEXT/2 (contact OR contacts)):ab,ti,kw
#36 ((hydrogel* OR hydrophilic* OR silicone* OR 'gas perm*') NEXT/2 (lens OR lenses)):ab,ti,kw
#37 ((soft OR disposable OR disposables OR daily OR dailies OR monthly OR monthlies OR weekly OR weeklies OR 'extended wear' OR 'continuous wear' OR hybrid* OR biweek* OR replacement*) NEXT/2 (contact OR contacts)):ab,ti,kw
#38 ((soft OR disposable OR disposables OR daily OR dailies OR monthly OR monthlies OR weekly OR weeklies OR 'extended wear' OR 'continuous wear' OR hybrid* OR biweek* OR replacement*) NEXT/2 (lens OR lenses)):ab,ti,kw
#39 #33 OR #34 OR #35 OR #36 OR #37 OR #38 
#40 'non prescription drug'/exp
#41 ('over‐the‐counter' OR 'over the counter' OR OTC):ab,ti,kw
#42 ('non‐prescription*' OR 'non prescription*' OR 'nonprescription*'):ab,ti,kw
#43 'eye drops'/exp
#44 'artificial tear'/exp
#45 ('artificial tear*' OR 'tear substitute*' OR eyedrop*):ab,ti,kw
#46 ((eye OR eyes OR ocular* OR ophthalmic* OR 'non prescripti*' OR nonprescripti* OR wetting OR rewetting OR lubricating) NEXT/2 (drop OR drops OR agent OR agents OR solution OR solutions)):ab,ti,kw
#47 'ointment'/exp
#48 (ointment* OR lubricant*):ab,ti,kw
#49 'demulcent agent'/exp
#50 demulcent*:ab,ti,kw
#51 'hydroxypropylmethylcellulose'/exp
#52 'methylcellulose'/exp
#53 (hypromellose OR 'cellulose derivative*' OR 'carboxymethylcellulose sodium' OR CMC OR 'hydroxypropyl methylcellulose' OR HPMC OR 'hydroxyethyl cellulose' OR methylcellulose OR methoxyhydroxypropylcellulose OR carbomer* OR cellulose):ab,ti,kw
#54 'dextran 70'/exp
#55 'dextran 70':ab,ti,kw
#56 'gelatin'/exp
#57 (gelatin* OR 'HP Guar' OR 'Carbopol type gel'):ab,ti,kw
#58 'macrogol derivative'/exp
#59 ('liquid polyol*' OR glycerin* OR 'polyethylene glycol*' OR 'PEG 300' OR 'PEG 400' OR 'polysorbate 80' OR 'propylene glycol*' OR 'polyhydric alcohol*'):ab,ti,kw
#60 'polyvinyl derivative'/exp
#61 ('polyvinyl alcohol*' OR polyvinylalcohol* OR PVA):ab,ti,kw
#62 (povidone OR polyvinylpyrrolidone):ab,ti,kw
#63 'hyaluronic acid'/exp
#64 'sodium hyaluronate':ab,ti,kw
#65 'emollient agent'/exp
#66 emollient*:ab,ti,kw
#67 'lanolin'/exp
#68 'paraffin'/exp
#69 'liquid paraffin'/exp
#70 'mineral oil'/exp
#71 'omega 3 fatty acid'/exp
#72 'Leptospermum'/exp
#73 (lanolin* OR paraffin*):ab,ti,kw
#74 ((castor OR mineral) NEXT/2 oil*):ab,ti,kw
#75 ('omega‐3' OR 'omega 3'):ab,ti,kw
#76 (manuka OR leptospermum):ab,ti,kw
#77 #40 OR #41 OR #42 OR #43 OR #44 OR #45 OR #46 OR #47 OR #48 OR #49 OR #50 OR #51 OR #52 OR #53 OR #54 OR #55 OR #56 OR #57 OR #58 OR #59 OR #60 OR #61 OR #62 OR #63 OR #64 OR #65 OR #66 OR #67 OR #68 OR #69 OR #70 OR #71 OR #72 OR #73 OR #74 OR #75 OR #76
#78 #39 AND #77
#79 #32 AND #78

Appendix 4. PubMed search strategy

1. ((randomized controlled trial[pt]) OR (controlled clinical trial[pt]) OR (randomised[tiab] OR randomized[tiab]) OR (placebo[tiab]) OR (drug therapy[sh]) OR (randomly[tiab]) OR (trial[tiab]) OR (groups[tiab])) NOT (animals[mh] NOT humans[mh])
2. "contact lens*"[tw] 
3. ((hydrogel*[tw] OR hydrophilic*[tw] OR silicone*[tw] OR "gas perm*"[tw]) AND (contact[tw] OR contacts[tw])) 
4. ((hydrogel*[tw] OR hydrophilic*[tw] OR silicone*[tw] OR "gas perm*"[tw]) AND (lens[tw] OR lenses[tw])) 
5. ((soft[tw] OR disposable[tw] OR disposables[tw] OR daily[tw] OR dailies[tw] OR monthly[tw] OR monthlies[tw] OR weekly[tw] OR weeklies[tw] OR "extended wear"[tw] OR "continuous wear"[tw] OR hybrid*[tw] OR biweek*[tw] OR replacement*[tw]) AND (contact[tw] OR contacts[tw])) 
6. ((soft[tw] OR disposable[tw] OR disposables[tw] OR daily[tw] OR dailies[tw] OR monthly[tw] OR monthlies[tw] OR weekly[tw] OR weeklies[tw] OR "extended wear"[tw] OR "continuous wear"[tw] OR hybrid*[tw] OR biweek*[tw] OR replacement*[tw]) AND (lens[tw] OR lenses[tw])) 
7. #2 OR #3 OR #4 OR #5 OR #6 
8. ("over‐the‐counter"[tw] OR "over the counter"[tw] OR OTC[tw])
9. ("non‐prescription*"[tw] OR "non prescription*"[tw] OR "nonprescription*"[tw])
10. ("artificial tear*"[tw] OR "tear substitute*"[tw] OR eyedrop*[tw])
11. ((eye[tw] OR eyes[tw] OR ocular*[tw] OR ophthalmic*[tw] OR "non prescripti*"[tw] OR nonprescripti*[tw] OR wetting[tw] OR rewetting[tw] OR lubricating[tw]) AND (drop[tw] OR drops[tw] OR agent[tw] OR agents[tw] OR solution[tw] OR solutions[tw]))
12. (ointment*[tw] OR lubricant*[tw])
13. demulcent*[tw]
14. (hypromellose[tw] OR "cellulose derivative*"[tw] OR "carboxymethylcellulose sodium"[tw] OR CMC[tw] OR "hydroxypropyl methylcellulose"[tw] OR HPMC[tw] OR "hydroxyethyl cellulose"[tw] OR methylcellulose[tw] OR methoxyhydroxypropylcellulose[tw] OR carbomer*[tw] OR cellulose[tw])
15. "dextran 70"[tw]
16. (gelatin*[tw] OR "HP Guar"[tw] OR "Carbopol type gel"[tw])
17. ("liquid polyol*"[tw] OR glycerin*[tw] OR "polyethylene glycol*"[tw] OR "PEG 300"[tw] OR "PEG 400"[tw] OR "polysorbate 80"[tw] OR "propylene glycol*"[tw] OR "polyhydric alcohol*"[tw])
18. ("polyvinyl alcohol*"[tw] OR polyvinylalcohol*[tw] OR PVA[tw])
19. (povidone[tw] OR polyvinylpyrrolidone[tw])
20. "sodium hyaluronate"[tw]
21. emollient*[tw]
22. (lanolin*[tw] OR paraffin*[tw])
23. ((castor[tw] OR mineral[tw]) AND (oil[tw] OR oils[tw]))
24. ("omega‐3"[tw] OR "omega 3"[tw])
25. (manuka[tw] OR leptospermum[tw])
26. #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 OR #21 OR #22 OR #23 OR #24 OR #25 
27. #7 AND #26
28. #1 AND #27
29. Medline[sb]
30. #28 NOT #29

Appendix 5. LILACS search strategy

("Contact Lens" OR "Contact Lenses" OR "Lentes de Contacto" OR "Lentes de Contato" OR MH:E07.632.500.276$ OR MH: VS2.006.001.009.001$ OR MH:D20.280.320.375$ OR MH:D26.255.165.320.375$ OR MH:D02.756.650.700$ OR MH:D05.750.900.850$ OR MH:D25.720.900.850$ OR MH:J01.637.051.720.900.850$ OR hydrogel$ OR hydrophilic$ OR silicone$ OR "gas permeable" OR ((soft OR disposable OR disposables OR daily OR dailies OR monthly OR monthlies OR weekly OR weeklies OR "extended wear" OR "continuous wear" OR hybrid$ OR biweek$ OR replacement$) AND (contact OR contacts OR lens OR lenses))) AND (MH:D26.530$ OR MH:VS2.002.001.006$ OR "over the counter" OR OTC OR "non prescription" OR nonprescription OR MH:D26.776.708.645$ OR MH:D27.505.954.578.645$ OR MH:D27.720.752.608$ OR "artificial tear" OR "artificial tears" OR "tear substitute" OR "tear substitutes" OR eyedrop$ OR ((eye OR eyes OR ocula$ OR ophthalmic$ OR wetting OR rewetting OR lubricating) AND (drop OR drops OR agent OR agents OR solution OR solutions)) OR MH:D26.255.640$ OR ointment$ OR lubricant$ OR MH:D27.505.954.158.515$ OR MH:D27.505.954.483.534$ OR MH:D27.505.954.796.210$ OR MH:D27.720.877.156$ OR Demulcent$ OR MH:D05.750.078.562.180.357$ OR MH:D09.698.365.180.455$ OR MH:D25.720.099.500.719$ OR MH:J01.637.051.720.099.500.719$ OR MH:D09.698.365.180.663$ OR hypromellose OR "cellulose derivative" OR "cellulose derivatives" OR "carboxymethylcellulose sodium" OR CMC OR hydroxypropylmethylcellulose OR "hydroxypropyl methylcellulose" OR HPMC OR "hydroxyethyl cellulose" OR methylcellulose OR methoxyhydroxypropylcellulose OR carbomer$ OR cellulose OR "dextran 70" OR MH:D12.776.860.476$ OR gelatin$ OR "HP Guar" OR "Carbopol type gel" OR MH:D02.033.455.250.700$ OR MH:D05.750.741$ OR MH:D25.720.741$ OR MH:J01.637.051.720.741$ OR "liquid polyol" OR "liquid polyols" OR glycerin$ OR "polyethylene glycol" OR "polyethylene glycols" OR "PEG 300" OR "PEG 400" OR "polysorbate 80" OR "propylene glycol" OR "propylene glycols" OR "polyhydric alcohol" OR "polyhydric alcohols" OR MH:D02.455.326.271.665.616$ OR MH:D02.455.326.271.884.533$ OR MH:D05.750.716.721$ OR MH:D25.720.716.721$ OR MH:J01.637.051.720.716.721$ OR "polyvinyl alcohol" OR "polyvinyl alcohols" OR polyvinylalcohol$ OR PVA OR povidone OR polyvinylpyrrolidone OR MH:D09.698.373.475$ OR "sodium hyaluronate" OR MH:D27.505.954.444.200$ OR emollient$ OR MH:D10.945.507$ OR MH:D02.455.612 OR MH:D02.455.699.500 OR MH:D10.212.302.380.410$ OR MH:D10.251.355.337$ OR MH:D10.627.430.450$ OR MH:B01.875.800.575.912.250.773.713$ OR lanolin$ OR paraffin$ OR "castor oil" OR "castor oils" OR "mineral oil" OR "mineral oils" OR "omega 3" OR manuka OR leptospermum)

Appendix 6. ClinicalTrials.gov search strategy

("contact lens" OR "contact lenses") AND ("over the counter" OR OTC OR nonprescription* OR "non prescription" OR "artificial tears" OR "tear substitute" OR eyedrop OR ((eye OR eyes OR ocular OR ophthalmic OR wetting OR rewetting OR lubricating) AND (drop OR drops OR agent OR agents OR solution OR solutions)) OR ointment OR lubricant OR Demulcent OR hypromellose OR "cellulose derivative" OR "cellulose derivatives" OR "carboxymethylcellulose sodium" OR CMC OR hydroxypropylmethylcellulose OR "hydroxypropyl methylcellulose" OR HPMC OR "hydroxyethyl cellulose" OR methylcellulose OR methoxyhydroxypropylcellulose OR carbomer OR cellulose OR "dextran 70" OR gelatin OR "HP Guar" OR "Carbopol type gel" OR "liquid polyol" OR glycerin OR "polyethylene glycol" OR "PEG 300" OR "PEG 400" OR "polysorbate 80" OR "propylene glycol" OR "polyhydric alcohol" OR "polyvinyl alcohol" OR polyvinylalcohol OR PVA OR povidone OR polyvinylpyrrolidone OR "sodium hyaluronate" OR emollient OR lanolin OR paraffin OR "castor oil" OR "mineral oil" OR "omega 3" OR manuka OR leptospermum)

Appendix 7. ICTRP search strategy

contact lens AND over the counter OR contact lens AND OTC OR contact lens AND nonprescription OR contact lens AND non prescription OR contact lens AND artificial tears OR contact lens AND tear substitute OR contact lens AND wetting OR contact lens AND rewetting OR contact lens AND lubricating OR contact lens AND drops OR contact lenses AND eyedrops OR contact lens AND agent OR contact lens AND agents OR contact lens AND solution OR contact lens AND ointment OR contact lens AND lubricant OR contact lens AND demulcent OR contact lens AND hypromellose OR contact lens AND cellulose derivative OR contact lens AND cellulose derivatives OR contact lens AND carboxymethylcellulose sodium OR contact lens AND CMC OR contact lens AND hydroxypropylmethylcellulose OR contact lens AND hydroxypropyl methylcellulose OR contact lens AND HPMC OR contact lens AND hydroxyethyl cellulose OR contact lens AND methylcellulose OR contact lens AND methoxyhydroxypropylcellulose OR contact lens AND carbomer OR contact lens AND cellulose OR contact lens AND "dextran 70" OR contact lens AND gelatin OR contact lens AND "HP Guar" OR contact lens AND carbopol type gel OR contact lens AND liquid polyol OR contact lens AND glycerin OR contact lens AND polyethylene glycol OR contact lens AND "PEG 300" OR contact lens AND "PEG 400" OR contact lens AND "polysorbate 80" OR contact lens AND propylene glycol OR contact lens AND polyhydric alcohol OR contact lens AND "polyvinyl alcohol" OR contact lens AND polyvinylalcohol OR contact lens AND PVA OR contact lens AND povidone OR contact lens AND polyvinylpyrrolidone OR contact lens AND sodium hyaluronate OR contact lens AND emollient OR contact lens AND lanolin OR contact lens AND paraffin OR contact lens AND castor oil OR contact lens AND mineral oil OR contact lens AND omega 3 OR contact lens AND manuka OR contact lens AND leptospermum OR contact lenses AND over the counter OR contact lenses AND OTC OR contact lenses AND nonprescription OR contact lenses AND non prescription OR contact lenses AND artificial tears OR contact lenses AND tear substitute OR contact lenses AND wetting OR contact lenses AND rewetting OR contact lenses AND lubricating OR contact lenses AND drops OR contact lenses AND eyedrops OR contact lenses AND agent OR contact lenses AND agents OR contact lenses AND solution OR contact lenses AND ointment OR contact lenses AND lubricant OR contact lenses AND demulcent OR contact lenses AND hypromellose OR contact lenses AND cellulose derivative OR contact lenses AND cellulose derivatives OR contact lenses AND carboxymethylcellulose sodium OR contact lenses AND CMC OR contact lenses AND hydroxypropylmethylcellulose OR contact lenses AND hydroxypropyl methylcellulose OR contact lenses AND HPMC OR contact lenses AND hydroxyethyl cellulose OR contact lenses AND methylcellulose OR contact lenses AND methoxyhydroxypropylcellulose OR contact lenses AND carbomer OR contact lenses AND cellulose OR contact lenses AND "dextran 70" OR contact lenses AND gelatin OR contact lenses AND "HP Guar" OR contact lenses AND carbopol type gel OR contact lenses AND liquid polyol OR contact lenses AND glycerin OR contact lenses AND polyethylene glycol OR contact lenses AND "PEG 300" OR contact lenses AND "PEG 400" OR contact lenses AND "polysorbate 80" OR contact lenses AND propylene glycol OR contact lenses AND polyhydric alcohol OR contact lenses AND "polyvinyl alcohol" OR contact lenses AND polyvinylalcohol OR contact lenses AND PVA OR contact lenses AND povidone OR contact lenses AND polyvinylpyrrolidone OR contact lenses AND sodium hyaluronate OR contact lenses AND emollient OR contact lenses AND lanolin OR contact lenses AND paraffin OR contact lenses AND castor oil OR contact lenses AND mineral oil OR contact lenses AND omega 3 OR contact lenses AND manuka OR contact lenses AND leptospermum

Contributions of authors

Concept, study design, drafting of the protocol: Andrew Pucker, Barbara Caffery, Ngozi Chidi‐Egboka, Nicole Carnt, Alison Ng, Brooke Harkness, and Obinwanne Chukwuemeka Jr.

Critical review and revision of the protocol: Andrew Pucker and Barbara Caffery.

Final approval before publication: Andrew Pucker, Barbara Caffery, Ngozi Chidi‐Egboka, Nicole Carnt, Alison Ng, Brooke Harkness, and Obinwanne Chukwuemeka Jr.

Sources of support

Internal sources

• None, Other

  No internal source of support.

External sources

• Public Health Agency, UK

  The HSC Research and Development (R&D) Division of the Public Health Agency funds the Cochrane Eyes and Vision editorial base at Queen's University Belfast.

• Queen's University Belfast, UK

  Gianni Virgili, Co‐ordinating Editor for Cochrane Eyes and Vision’s work is funded by the Centre for Public Health, Queen’s University of Belfast, Northern Ireland.

• National Eye Institute, National Institutes of Health, USA

  Cochrane Eyes and Vision US Project, supported by grant UG1EY020522 (PI: Tianjing Li, MD, MHS, PhD)

Declarations of interest

Barbara Caffery: None known

Andrew D Pucker: None known

Ngozi C Chidi‐Egboka: None known

Obinwanne Chukwuemeka Junior: None known

Brooke Harkness: None known

Nicole A Carnt: None known

Alison Ng: None known

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