Should I fit orthokeratology to a potential keratoconic?
In this article:
MCS was hesitating fitting OrthoK to a patient who showed inferior corneal steepening. Her main concern was that OrthoK may induce corneal ecstasia/keratoconus in the future and whether there is a link between OrthoK and keratoconus.
Is the patient a keratoconic?
Some commenters suggested retaking good quality and well-centred topographic images and pachymetry would give more confidence in eliminating potential keratoconus.
With this being the first visit and hence no evidence yet of progressive change in the corneal profile, evaluating the patient's risk factors for keratoconus may aid a decision. The risk factors include eye rubbing, atopy and a positive family history.1 In the case of this patient, only intermittent eye rubbing and 'allergies' are mentioned.
Considerations for orthokeratology
Other than concerns that OrthoK may cause undue stress on a potentially ectactic cornea, there was discussion that OrthoK might not be very effective on a low myope compared to other possible myopia control treatments.
The current research indicates that this assertion is not supported by scientific evidence. Read more on this topic in our blog Is orthokeratology useful for control of low myopia? The sum total is that OrthoK is likely to work just as well for lower and higher myopes, and just as well (and maybe better) than MFCLs. Current meta-analyses indicate that OK has the greater volume of myopia control evidence but the overall efficacy is likely similar as for MFCLs.
OrthoK and keratoconus?
There is no research data or case reports indicating OrthoK may precipitate the development of keratoconus. As noted above, it's important to determine the level of concern for keratoconus in this patient with further testing and monitoring.
It makes intrinsic sense that we would not want to put undue pressure on a keratoconic cornea, such that keratoconus would typically be considered a contraindication for OrthoK. However there are a handful of case reports and abstracts, and even a 2009 clinical trial on use of OrthoK for keratoconus. The inclusion criteria for this clinical trial was moderate KC with no apical scars; advanced KC with apical scarring was excluded. A literature search reveals no published papers from this trial, or any other peer reviewed full-length article on the topic - it could be due to the potential controversy of this area of OrthoK practice. Here's links to the case reports and abstracts.
- Dantas et al, 2017: A 26 year old man 'with keratoconus' was reported to be fit with OrthoK, but outcomes are not described. Interestingly, his corneal thickness was normal and spectacle acuity was described as 'OD 20/20 OS 20/40.' Topography maps are not provided.
- Goyal et al, 2009: A week of pre-operative OrthoK wear followed by corneal collagen cross-linking (CxL) in 9 young adults was compared to 10 young adults who had CxL only. No difference in steep K or total astigmatism between the groups 6 months after CxL.
- Calossi et al, 2010: Five eyes of four young adult keratoconus patients were fit with OrthoK for 3 months, then underwent CxL. After a one month break post CxL, the topography had returned to baseline. OrthoK was then recommenced with a piggyback system for a three weeks then the OrthoK lenses only for a further two months. The authors reported no adverse reactions in the three months of pre-CxL OK, but no lasting benefit to doing the OK.
- Yamada et al, 2005: A newly developed 'OrthoK like procedure' customized contact lens design for overnight wear was trialled on 62 eyes of 41 keratoconus patients, including some children. With average unaided acuity of 20/60 (6/18) or worse, 82% improved to 20/30 (6/9) or better and eye health outcomes were reported as good over at least two years of follow up.
Here at Myopia Profile we endorse safe OrthoK practice. Reviews of OrthoK safety focus on the risk of infection and OrthoK studies typically list any corneal irregularity or keratoconus suspicion as an exclusion criteria. There's simply very little on OrthoK and keratoconus in the literature.
Considerations for myopia control treatments
Compared to OrthoK, for this patient where there could be concern of corneal irregularity, alternative options such as MFCL, myopia control spectacles lenses and atropine were considered 'safer' as they would be much less likely to 'disturb' the corneal surface. This would eliminate the concern for exerting pressure on a potentially ectactic cornea and allow for much easier monitoring for any developments of ectasia.
- MFCLs would provide clear vision and help to slow myopia progression at the same time.
- If the patient's eye-rubbing habits render him unsuitable for contact lens wear, myopia control spectacle lens are an option too. Check out our research write-up covering the latest updates on myopia control spectacle lenses.
- Atropine may be used as a standalone treatment or in combination with any of the optical interventions discussed above. Research of combination treatment is limited but evolving. There is only one study2 that compared the efficacy of multifocal spectacle lens used in combination with 0.5% atropine (and found that multifocal spectacle lens did not contribute to myopia control). The Bifocal & Atropine in Myopia (BAM) Study3 that investigates the efficacy of bifocal soft CLs combined with atropine is currently underway, as is the similar OrthoK and atropine study.4 Only baseline data have been reported for each at this stage.
Take home messages
- To maximise safety in OrthoK practice, it is prudent to ensure that there is no keratoconus, corneal ectasia or irregular astigmatism before fitting. If there is concern for potential keratoconus, consider alternative myopia control interventions whilst monitoring change in corneal profile.
- If your patient has allergies and eye-rubbing habits, the importance of proper contact lens handling and hygiene needs to be emphasised.
- There is currently no supportive evidence for OK being less effective in lower myopia, and no evidence suggesting that MFCLs are comparatively more effective by level of myopia. Pick what CL option suits your patient best.
Meet the Authors:
About Kate Gifford
Dr Kate Gifford is a clinical optometrist, researcher, peer educator and professional leader from Brisbane, Australia, and a co-founder of Myopia Profile.
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.
About Kimberley Ngu
Kimberley is a clinical optometrist from Perth, Australia, with experience in patient education programs, having practiced in both Australia and Singapore.
- Gordon-Shaag A, Millodot M, Shneor E, Liu Y. The genetic and environmental factors for keratoconus. Biomed Res Int. 2015;2015:795738 (link)
- Shih YF, Hsiao CK, Chen CJ, Chang CW, Hung PT, Lin LL. An intervention trial on efficacy of atropine and multi-focal glasses in controlling myopic progression. Acta Ophthalmologica Scandinavica. 2001;79(3):233-6 (link)
- Huang J, Mutti DO, Jones-Jordan LA, Walline J. Bifocal & atropine in myopia (BAM) study: Baseline data and methods. Optom Vis Sci. 2019 May; 96(5):335-344 (link)
- Tan Q, Ng AL, Cheng GP, Victor CP Woo VP & Cho P. Combined Atropine with Orthokeratology for Myopia Control: Study Design and Preliminary Results, Current Eye Research 2019:44:6, 671-678, DOI: 10.1080/02713683.2019.1568501 (link)
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