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How can we promote safety in orthokeratology?

 Posted on November 22nd 2021 by Connie Gan

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In this article:

Many orthokeratology incidents are due to poor compliance and hygiene processes. This case describes patient education key procedures.

How can we best promote safety in orthokeratology (OK) wear? Many OK lens related incidents are due to poor lens handling and hygiene processes.1 Here is a case described by PC of a child who suffered microbial keratitis, which, on questioning, appeared to be associated with inappropriate OK lens care.

PC This case might give us some food for thought. None of my OrthoK fits have had any kind of infective or infiltrative event - touch wood they never do. This patient was referred to me by an ophthalmologist a few weeks ago. 12yo male had been wearing OK from China for 4 years. Recently he had an “infection” that required Ofloxacin treatment. On examination the keratitis had resolved, with only fading scars from 2 small peripheral infiltrates and no central corneal involvement. Refraction -2.75D R&L (AXL 25.7mm). We discussed other options of myopia control but he didn’t want glasses or soft lenses, insisting on continuing with OK. To avoid wearing the same old pair of lenses of unknown design and materials, we decided to start fresh from his current Rx and topography, to ensure properly fitted lenses which is a good basis for safe OK wear. At lens delivery, while going through lens hygiene procedures, it became apparent that the only solution he had used for “disinfection” for the past 6 months (after running out of his Menicare Plus supply from China) was... Lens Plus saline! 😲 Um, 2 green bottles with the word “Plus” don’t mean the same thing He also had no ongoing reviews since moving to Australia. Key message: Yes there are some risks with OK wear, as with any kind of CL wear in both adults and kids, but the chance of MK leading to vision loss is very, very low. But we need to ensure patients do the right things - patient education and communication is vital! My patients all have my mobile number and are instructed to call/text me if they ever have any questions or concerns. Long-term wearers may become more complacent so always check their lens care routine. And make sure they attend their regular reviews!

Ensuring compliance in OK wear

BR I come across poor compliance all the time which is why I’m such an advocate for daily disposable lenses… patients were only using saline to clean their lenses… They were also sleeping in focus dailies for up to 1 month…PR I agree with BR- in my experience the majority of contact lens complications (OK or otherwise) arise because of non compliance, yet somehow its the products that get tarnished with being 'bad'.PC I think it’s a lack of knowledge in this case rather than compliance. When told properly, his mum promptly bought 3 bottles of Menicare Plus with no hesitation…

Poor compliance with contact lens hygiene processes can lead to OK lens-related infections.1 The main reasons for poor compliance consist of lack of knowledge for procedures and the potential consequences of non-compliance.2

Surveys have shown that the full OK lens compliance rate in young wearers was 23% in Taiwan3 and 14% in China.4  In Taiwan, a highly educated parent group were surveyed who were mostly myopic themselves. Their children were all 6-13 years of age and parents took responsibility for lens hygiene processes. Compliance was uniformly reported as high for lens and lens accessory cleaning processes, and was highest in newer wearers (less than 6 months). Lowest compliance rates were for "intensive care for lenses (removing lens protein deposition)".3

In China, children who had worn OK for at least one year were surveyed. The most common areas of non-compliance were exposure to nonsterile solution (eg. water, from not drying hands properly), not removing lens depositions according to the eye care practitioners' (ECPs) recommendations and inadequate hand washing.4

Children undertaking lens care themselves were less compliant than children whose lens care was supervised or undertaken by their parents.4 Another study of long-term OK wearers with an average age of 12.7 years found a higher microbial bioburden of the OK care system in male participants.5 Reinforcement of the lens cleaning process is important for all patients - especially for children undertaking lens care themselves and young male wearers. Explanations that include the reasoning behind each step could strengthen the patient's attitude towards the importance of being compliant.2

AC I actually have a picture of that specific saline on my contact lens aftercare instruction sheet, stating “This is NOT to be used to clean your lenses, it is just saline”.SHW When you discussed other CL options with this patient, it seems that this patient doesn't really want to change his lifestyle. So there is a risk that he won't be compliant with Ortho-K in a short time. We can also put these kind of patients on H2O2 solution, it will reduce the chance of an infection through CL wear PC …I was concerned about prescribing H2O2 in this case due to poor English and potentially using it like a multipurpose solution.

The community also shared some tips on improving compliance. As the lens care procedures may appear complicated to the parents and wearer, a printed handout with pictorial references can be useful for patients to remember the instructions.

Rubbing OK lenses whilst cleaning improves removal of depositing6 and additional protein removal cleaner removes further depositing and biofilm from gas permeable lenses better than the routine cleaning solution alone.7 This should be an important part of OK lens cleaning procedures.

What about lens cases? A study of almost 200 asymptomatic OK patients aged 7 to 17 years attending a hospital clinic in China investigated lens case hygiene processes and collected cases for analysis. The least contamination was found with when lens cases were rinsed with multipurpose solution and wiped with a tissue daily, and replaced every month. Cylindrical lens cases were less contaminated than flat lens case types.8

Key message: no water near lenses!

A key factor which may compromise the safety of OK lens wear is exposure to tap water - the most common risk factor for Acanthamoeba keratitis,9,10 which unfortunately makes up over one-third of all cases of OK-related microbial keratitis.11 

Exposure can occur regularly when the wearer doesn't thoroughly dry their hands after washing, or rinses the contact lens, case or accessories with water. An example of this is described in a case study of severe Acanthamoeba infection, where the patient cleaned his lenses as instructed, but then rinsed and stored his lenses in tap water, and didn't clean or replace the lens case. The authors concluded that "heightened scrutiny [of lens hygiene] is critically important in orthokeratology rigid lens wear, especially in children".12


Regular follow up is crucial

Follow up is essential for the practitioner to monitor treatment outcomes as well as to examine eye health, regularly replace lenses and review lens care procedures. Jun et al showed that the rate of compliance with follow up appointments in China reduced from close to 100% in the first 3 months to around 85% after 6-9 months.4

It has been found that the average duration of wearing time before a case of microbial keratitis is 19 months.11 This indicates the importance of explaining the reasons for follow up and establishing patient education and practice procedures to ensure adherence.

How safe is orthokeratology?

The risk of microbial keratitis in childhood ortho-k wear is between 5 and 14 per 10,000 patient-wearing years.13,14

Data gathered from almost 200 ECPs in the United States for clinical care between 2004 and 2006 representing 677 children with 1435 patient-years of wear estimated the first incidence rate of 13.9 per 10,000 patient years of wear.13 The second, lower figure was from a recent study surveying a group of ophthalmology and optometry practices in Moscow, Russia, representing care occurring between 2010 and 2018 and just over 1000 records analyzed. The incidence in this newer study was estimated to be between 4.9 and 5.3 per 10,000 patient years of wear.14

The improved safety profile in this recent study could reflect the impact of gathering data from a single group of practices with standardized training, whereas the previous study obtained data from numerous different practices. It could also reflect a concerted effort to improve ortho-k safety and compliance in the years since the significant concerns about infection were raised in the early 21st Century.1

Another study reviewed the ocular health of 489 OK-wearing eyes in 260 patients presenting consecutively over one year (2016) in China. Children were 8-15 years old with a mean refraction of -3.2D. There were no cases of microbial keratitis, 5 cases (1%) of corneal infiltrates and 29 cases (6%) with corneal staining of at least Grade 3. Interestingly, 14% had allergic conjunctivitis which increased the likelihood of Grade 2 or less corneal staining by 1.7 times, but did not increase the risk of corneal infiltrates or Grade 3+ staining.15

Finally, a study which evaluated 10 years (2002 to 2012) of OK versus soft contact lens wear in children, in a single clinical setting, found no cases of microbial keratitis and no difference in adverse event rates between lens types, with a rate of 0.1% per year for corneal erosion and 3.5% per year for superficial punctate keratopathy, which was the most frequent adverse event. All adverse events resolved with short-term discontinuation of lens wear and/or application of topical drops or medications as required, and all patients resumed OK lens wear after resolution, indicating "the acceptable safety of OK treatment over long periods of lens wear."16

Take home messages:

  1. When cared for properly, OK lenses are a safe and effective option for myopic children.
  2. Many OK-related adverse events are due to improper lens care procedures. In addition, longer wearing time is associated with decreased compliance and increased risk of an adverse event. This means that the safety of OK can be promoted with proper parent and wearer education on hygiene and lens care procedures, plus reinforced explanations and adherence to regular follow up.

Further reading

Meet the Authors:

About Connie Gan

Connie is a clinical optometrist from Kedah, Malaysia, who provides comprehensive vision care for children and runs the myopia management service in her clinical practice.

Read Connie's work in many of the case studies published on MyopiaProfile.com. Connie also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

About Kimberley Ngu

Kimberley is a clinical optometrist from Perth, Australia, with experience in patient education programs, having practiced in both Australia and Singapore.

Read Kimberley's work in many of the case studies published on MyopiaProfile.com. Kimberley also manages our Myopia Profile and My Kids Vision Instagram and My Kids Vision Facebook platforms.

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