Adverse event rates in paediatric soft contact lens wear

Authors: Robin L Chalmers (1), John J McNally (2), Paul Chamberlain (2) and Lisa Keay (3,4)

1. Clinical Trial Consultant, Atlanta, USA
2. CooperVision, Inc., Pleasanton, USA
3. School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW, Australia
4. The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia

Date: Nov 2020

Reference: Ophthalmic Physiol Opt. 2020;41:84-92 [Link to open access paper]

One of the major challenges for augmenting the recommendation and implementation of contact lenses in the paediatric population is the perceived risk, by eye care professionals and parents alike, of complications.¹ As the prescribing rates of soft contact lenses (SCL's) increases in children in order to combat myopic progression, it is essential to gain a thorough understanding of their safety.

This retrospective cohort study established the prevalence of adverse events (AEs) in children wearing SCL's. It reported rates of microbial keratitis (MK) and other inflammatory adverse events in children wearing SCL's that are comparable to established rates among adults wearing SCL's. These results can be utilised to provide assurance of an acceptable range of safety during SCL wear in children to both parents and eye care practitioners alike.

The study reported rates of MK and other inflammatory adverse events in children wearing SCL's that are less than or comparable to adults

• The safety and possible AE's associated with SCL wear should always be discussed with the patient and their parents prior to commencing SCL wear
• This research shows that concern over safety should not be viewed as a deterrent to prescribing SCL's in our paediatric patients
• The analysis outlined in this paper can be used to give confidence to Eye care professionals in advising and counselling patients and their parents of the relative safety of SCL's

Read more about the research evidence and clinical communication on Contact Lens Safety in Kids via this link

There is potential for error in the reporting of different types of AE's due to the retrospective data collection. To minimise the problems of retrospectively diagnosing MK and other adverse events from clinical records, the authors formed an Adjudication Panel with predetermined diagnostic criteria. Interestingly, the Adjudication Panel reached a unanimous decision on less than half of the diagnoses. A telephone discussion was required in these cases to reach a consensus. 

• Consequently, while the total number of adverse events is likely accurate, the differentiation between certain adverse events (CLPC and allergies conjunctivitis for example) is difficult to make retrospectively based on clinical notes 
• A prospective study or national paediatric SCL database would provide greater clarity in the future. 

Potential risk of under-reporting of adverse events:

• Only 5 of the 7 US sites agreed to active follow up of patients who had not attended the practice in the previous 9 months. Consequently, 6.9% of subjects had either not responded with their disposition or not been examined in 9 months. 
• Furthermore, the authors did not report the rate of adverse events that were detected by active follow up of patients at the 5 US sites. Consequently, it is difficult to establish the level of significance of the loss of follow up to 2 of the sites. It is reasonable to expect that the rate of adverse events could be higher had these patients been included. 

Due to the nature of the study, it is not possible to examine risk factors for AE's that were observed:

• There was no further investigation or questionnaire at the time of the adverse events that examined possible risk factors (overnight wear, swimming) 
• Consequently, the authors were unable to extrapolate risk factors that may predispose to adverse events. 

Future research regarding safety of SCL's is required in a broader population of children, including further racial, cultural and socioeconomic diversity to gain additional knowledge: 

• While the authors of the study sampled SCL's wearers from a variety of clinics across the US and attempted to observe diverse racial, economic and geographic, further research is required in varied populations to ensure consistent findings.

To retrospectively establish the prevalence of adverse events in children wearing SCL's through analysis of clinical charts from optometry practices across the US and an audit of clinical notes from two randomised controlled trials.

Two separate groups of children, totalling 963, wearing SCL's were analysed in this study. Firstly, the clinical records of 782 children wearing SCL's from 7 US clinics were examined for potential adverse events. If a child had not been examined in the 9 months prior, the authors contacted the parents to enquire about any episodes of "red or painful eyes that required a visit to an eye doctor or emergency room since their last visit". 2 out of 7 of the US clinics declined permission for this active follow up of their patients. 

Secondly, an audit of two international randomised control trials which included 181 children was undertaken to determine the prevalence of adverse events.^2,3

The children had a mean age of 10.5 years when fitted in SCL's (ranged from 8-12 years of age) and were followed up for on average 2.8 ± 1.5 years. The children were wearing a variety of different branded CL's, with varying powers and replacement modalities. 

An Adjudication Panel retrospectively analysed potential AE's from electronically scanned clinical records of a total of 963 children. This totalled to 2713 years of contact lens wear with 4611 contact lens visits.

The study reported a combined annual rate of adverse events (MK and other inflammatory AEs) of 0.74%/year. This compares well to the 0.97%/year reported in the Contact Lens Assessment in Youth (CLAY) study in children aged 8-12 years.⁴ A breakdown of rates of CIE events are detailed in the table below. The annualised rate of MK was reported as 7.4/10, 000 years of wear, which reflects 2 cases of MK. 

Table 1: Annualised Rate of Significant Adverse Events in the ReCSS study. Note CLPC= contact lens papillary conjunctivitis, IK= infiltrative keratitis, CLARE= contact lens acute red eye, CLPU= contact lens peripheral ulcer 

The study reported lower or  comparable risk of adverse events in SCL wear in children aged 8-16 to that of an adult population. This knowledge may allay both eye care practitioners and parents concerns regarding the safety of SCL use in the paediatric population in the real world.

Title: Adverse event rates in the retrospective cohort study of safety of paediatric soft contact lens wear: the ReCSS study

Authors: Robin L Chalmers, John J McNally, Paul Chamberlain and Lisa Keay

Purpose: To ascertain the safety of soft contact lens (SCL) wear in children through a retrospective chart review including real‐world clinical practice settings.

Methods: The study reviewed clinical charts from 963 children: 782 patients in 7 US eye care clinics and 181 subjects from 2 international randomised clinical trials (RCTs). Subjects were first fitted while 8-12 years old with various SCL designs, prescriptions and replacement schedules, and observed through to age 16. Clinical records from visits with potential adverse events (AEs) were electronically scanned and reviewed to consensus by an Adjudication Panel.

Results: The study encompassed 2713 years‐of‐wear and 4611 contact lens visits. The cohort was 46% male, 60% were first fitted with daily disposable SCLs, the average age at first fitting was 10.5 years old, with a mean of 2.8 ± 1.5 years‐of‐wear of follow‐up observed. There were 122 potential ocular AEs observed from 118/963 (12.2%) subjects; the annualised rate of non‐infectious inflammatory AEs was 0.66%/year (95% CI 0.39-1.05) and 0.48%/year (0.25-0.82) for contact lens papillary conjunctivitis. After adjudication, two presumed or probable microbial keratitis (MK) cases were identified, a rate of 7.4/10 000 years‐of‐wear (95% CI 1.8-29.6). Both were in teenage boys and one resulted in a small scar without loss of visual acuity.

Conclusion: This study estimated the MK rate and the rate of other inflammatory AEs in a cohort of SCL wearers from 8 through to 16 years of age. Both rates are comparable to established rates among adults wearing SCLs.

[Link to open access paper]