Optimizing safety in orthokeratology

Orthokeratology (ortho-k) is prominently known for its effectiveness in myopia control, with numerous studies and meta-analyses indicating ortho-k's ability to slow axial eye growth by around half compared to a single-vision corrected child.¹ Practitioner survey data has indicated that ortho-k is perceived as the most effective method of myopia control.² Ortho-k also holds the special distinction of being the only intervention with evidence for slowing aniso-myopic eye growth,³ in the presence of astigmatism up to 3.50DC,⁴ and for partial treatment of high myopes from -6D to -8D.⁵

Ortho-k lens technology has been around for decades, and while it currently has relatively low prescribing rates across the world, its use is growing.^6,7 Safety is cited as a potential barrier for eye care practitioners (ECPs) yet to uptake ortho-k, and also a reason for discontinuation of wear, yet a recent US survey of ECPs fitting ortho-k noted that the safety profile was high in practice, with "86% of respondents [reporting] that microbial keratitis was rarely or never seen."⁷

There is no doubt that safety is optimized by ensuring patient compliance. Prescribing ortho-k for myopia control means that the wearer is typically a child - hence, it is not only the patient but the parents that are involved in compliance.

Why is compliance so important with ortho-k use? Orthokeratology is a multiple-step process, and its use necessitates daily behavioural changes. Several steps are required in patient education- the need to wear them every night, the need for a full 6-8 hours of sleep, for cleaning and storing, and for ongoing follow-up appointments. In a survey conducted in China of 400 ortho-k wearers aged 9-22 years, only 18.5% were found to comply fully with all safety and hygiene protocols. Wearer age, sex, or duration of wearing experience did not influence levels of compliance.⁸ An important finding of this survey was that children who are solely responsible for lens care are less compliant than children who are supervised or assisted by their parents.⁸

A similar study conducted in Taiwan surveyed the parents of pediatric ortho-k wearers, most of which were university educated and myopic themselves: they found that 80% of parents were highly compliant on most aspects of orthokeratology use.⁹ Involvement of parents or caregivers with ortho-k lens care protocols is a critical tool in supporting  compliance. It is crucial that children - should they be independent lens carers - thoroughly understand all the steps involved in orthokeratology wear.

Non-compliance is not a result of willful intent not to comply, nor inaction: rather, it mostly stems from incomplete or improper performance of protocols.⁸ Incomplete performance of ortho-k lens care steps may be the result of inconvenient and cumbersome cleaning protocols - hence, it is important to recommend products that are easy to use, as well as effective. Incomplete performance of protocols can be the result of inadequate patient education, ineffective communication between the ECP, patient and parent, or simply inattention and forgetfulness. For this reason, it is helpful to remind patients and their parents of these essential processes at every follow-up appointment, and to reinforce their importance. Ideally, instructions and assistance in compliance steps should be able to be provided, if needed, between in-person appointments to reinforce protocols.

Compliance with follow-up ortho-k appointments is also crucial. Compliance with appointments is typically excellent at the beginning, with 100% attendance to appointments in the first 3 months; however, a drop-off can then occur, with attendance rates dropping to 85-90% between the 3-9 month point.⁸ One of the most common non-compliance habits is not adhering to recommended appointment schedules.⁹ 40% of ortho-k wearers cite "lack of time" and 22% cite "no discomfort" as reasons for non-attendance.⁸ Key to addressing this hurdle is communicating to patients the importance of follow-ups, even in their experience of good vision and eye health - concluding each ortho-k consultation with a short statement on the importance and reasons for the next follow up is recommended.

There is a large volume of evidence to indicate that ortho-k is a safe option for myopia correction and control in children.¹⁰ The risk of microbial keratitis in children wearing ortho-k has been found to be around 1-2 cases per 2,000 wearers, per year.^11,12 In the clinical setting, a study which evaluated outcomes in orthokeratology versus soft contact lens wear in children found no difference in the rate of adverse events over 10 years of wear. Around 10% of wearers experienced some adverse event over this 10 year follow-up period, but these were primarily issues of conjunctivitis and corneal staining which were clinically mild, and no cases of microbial keratitis were observed in that study.¹³

Another clinical data report found that 66% of ortho-k wearing children experienced no adverse effects after a mean of 28 months of wear. The most common observation was corneal staining, which occurred in around 1 in 10 childhood wearers per year, but was reported as mostly  Grade 1 or Grade 2 and resolved without any intervention. None of these patients discontinued ortho-k wear.¹⁴ One further study reported that around 13% of ortho-k wearing eyes will experience an adverse event over one year of lens wear, with the vast majority of these being non-significant events - defined as of no immediate clinical concern and not warranting discontinuation from lens wear.¹⁵

How can we optimize safety in ortho-k? The keys here are to encourage the best possible patient compliance, including with all steps of lens care and follow-up appointments. Effective in-room clinical communication on lens care processes should ideally be reinforced with instructions and support which the patient and their parents or carers can access between in-person appointments.

Ortho-K lenses retain more bacteria than traditional alignment fit gas permeable lenses due to their unique curvature changes.¹⁶ This means that biofilm build-up and micro-organisms need to be properly managed through optimized lens care and hygiene practices.¹⁷ These practices include lens solutions: a multi-purpose lens care solution can be used for cleaning, conditioning, disinfecting and rinsing the lenses for daily wear. Practitioners should encourage the use of the 'Rub-and-rinse' technique whereby patients rub the contact lenses while cleaning and rinse them off with the same solution, as this removes deposits more effectively.¹⁸ Additionally, a dedicated protein-deposit removing solution should also be recommended.¹⁹ These products and procedures must be explained adequately to ensure compliance.

Prescribing regulatory approved treatments also helps to manage safety. There are different levels of safety and efficacy evidence required for various regulatory approvals - for example, United States FDA and European CE marking are not interchangeable. An example of off-label prescribing of a medical device is where an orthokeratology lens, which is FDA approved or CE marked for myopia correction in adults, is prescribed for myopia control in children. Off-label use cannot be marketed by companies, and while not illegal for practitioners to prescribe, requires additional informed consent processes. Read more about this in Understanding on- and off-label prescribing.

Orthokeratology is one of the most well-researched and established means of myopia control.^1-4 When a young patient and their parents choose orthokeratology, they are signing up for a treatment which can significantly improve their confidence and lifestyle,²⁰ yet also requires a change in their daily habits. Compliance is crucial for healthy ocular and visual outcomes in ortho-k. For the eye care practitioner, optimizing in-room communication and between-appointment patient support, and understanding the reasons behind patient non-compliance, will help to overcome these issues and optimize your patients' likelihood of ortho-k wearing success.

1. Most non-compliance in ortho-k wearers is not wilful, but rather improper or incomplete performance of care processes. Manage this by discussing the detail of lens care processes at each appointment, and providing additional resources for at-home support.
2. Children who undertake all ortho-k lens care by themselves can be less compliant than those who have support from parents or carers. Manage this by ensuring children and parents understand all steps required in lens care.
3. Compliance with follow up appointments can fall off after 3 months of wear. Manage this by explaining why they are necessary, even if the patient is experiencing uncomplicated wear.

• Understanding On- And Off-Label Prescribing

• Science Review: How Common Is Microbial Keratitis In Children Wearing Orthokeratology?

• Case Study: Getting Parents Onboard With Orthokeratology

• Case Study: Orthokeratology: Is it a compliance issue or lens fitting problem?