Quantitative evaluation of regular and irregular corneal astigmatism in patients having overnight orthokeratology

Hiraoka, Takahiro; Furuya, Airi; Matsumoto, Yoshiteru; Okamoto, Fumiki; Sakata, Nobuchika; Hiratsuka, K.; Kakita, Tetsuhiko; Oshika, Tetsuro

doi:10.1016/j.jcrs.2004.02.049

Cited by 28 publications

(15 citation statements)

References 15 publications

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“…Likewise, findings of corneal warpage and induced, irregular surface astigmatism have recently been reported by Hiraoka et al 1 , who demonstrated both a significant increase in both regular and irregular astigmatism even in clinically successful orthokeratology cases. Interestingly, however, the amount of myopic correction correlated significantly with the increase in the asymmetry component (Pearson correlation coefficient; R ϭ 0.40, P ϭ 0.0009) but not with the increase in regular astigmatism (R ϭ 0.24, P ϭ 0.55).…”

supporting

confidence: 63%

Summary and Future Directions— Basic Science

Cavanagh¹

2004

Eye & Contact Lens: Science & Clinical Practice

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There are three principal clinical issues that urgently need to be addressed by basic laboratory and clinical science studies of orthokeratology lens wear:1. Increased microbial infection rates (especially in children); 2. Permanent corneal warpage effects, especially associated with irregular surface astigmatism; and 3. Concern for exhausting the finite capacity for mitotic proliferation of corneal limbal stem cells over decades of overnight orthokeratology lens wear.The basic premise for such studies is that basic clinical or laboratory science experiments can assess risks, and that once risk is known, it can be managed ethically and scientifically by patients and practitioners.Infection concerns are real. A hyper-oxygen transmissible, alignment-fitted rigid gas-permeable lens that produces no increase in Pseudomonas aeruginosa (PA) binding in 30-night extended wear in humans or 24 hour wear in rabbits, when cast in CRT-design, increases PA binding in the rabbit model. Rabbit fits are not completely like humans, so what does happen in humans? This needs to be studied immediately.Likewise, findings of corneal warpage and induced, irregular surface astigmatism have recently been reported by Hiraoka et al. 1 , who demonstrated both a significant increase in both regular and irregular astigmatism even in clinically successful orthokeratology cases. Interestingly, however, the amount of myopic correction correlated significantly with the increase in the asymmetry component (Pearson correlation coefficient; R ϭ 0.40, P ϭ 0.0009) but not with the increase in regular astigmatism (R ϭ 0.24, P ϭ 0.55). Importantly, these findings were not accompanied by an adverse effect on visual acuity.The take-home message here is clear. The central compressive area needs to be smooth, centered, and predictable in the closed eye. We need the best possible centration lens design, i.e., improved fitting algorithms, preferably fit from inventory.Finally, concerns about potentially increased orthokeratologyinduced demands on long-term corneal limbal stem cell mitotic renewal of the corneal epithelium can only be answered in the animal model (rabbit, cat). The preliminary experiments reported by Matsubara et al. 2 also need to be confirmed and eliminated by better lens centration and compression algorithms.In summary, using properly fit and monitored orthokeratology lenses, there are no major contraindications to date that have been established by currently reported basic or clinical science studies. There are however, concerns that need to be addressed by appropriate future clinical and/or bench investigations.Once we understand how orthokeratology lens wear alters or does not alter significantly corneal health long-term, risk can be assessed and then appropriately addressed in patients of any age. REFERENCES1. Hiraoka T, Furuya A, Matsumota Y, et al. Quantitative evaluation of regular and irregular corneal astigmatism in patients having overnight orthokeratology.

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supporting

confidence: 63%

Summary and Future Directions— Basic Science

Cavanagh¹

2004

Eye & Contact Lens: Science & Clinical Practice

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“…No significant refractive cylindrical change was noted during the six-month ortho-k treatment, however, some researchers have reported changes in with-the-rule corneal astigmatism in their ortho-k subjects. [17][18][19]…”

Section: Refraction and Unaided Visionmentioning

confidence: 99%

Orthokeratology practice in children in a university clinic in Hong Kong*

Chan

Cho

Cheung

2008

Clinical and Experimental Optometry

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Purposes:The aim of this study was to analyse clinical data of children undergoing orthokeratology (ortho-k) and to investigate patients'/parents' perspective on ortho-k via telephone interviews. Methods: Clinical records of children undergoing ortho-k from a university optometry clinic were reviewed and the effects of ortho-k on refraction, vision and cornea were investigated. A telephone interview was conducted to solicit patients'/parents' perspective of the treatment. Results: One hundred and eight files were reviewed. Median age of the children was nine years (range six to 15); mean (ϮSD) pre-treatment refractive sphere was -3.56 Ϯ 1.49 D and the median refractive cylinder was -0.50 D (range zero to -4.25 D). Significant refractive spherical reduction (58 per cent), improvement in unaided vision and corneal topographical changes were noted after only one night of wear. No significant change in astigmatism was found. Corneal staining was the most commonly observed complication with ortho-k and more than 80 per cent of patients were advised to apply ocular lubricants to loosen the lens before lens removal. Ortho-k was mainly undertaken for myopic control and about 90 per cent of the respondents reported good/very good unaided vision after ortho-k and ranked the treatment as satisfactory or very good. Lens binding and ocular discharge were the most frequently reported problems during the treatment. Conclusion: Under close monitoring, overnight ortho-k is effective and safe for reducing low to moderate myopia and the treatment is well accepted by the children.

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“…Recently, several studies have demonstrated that overnight orthokeratology causes declines in optical quality of the eye, such as increases in corneal irregular astigmatism17 and higher-order wavefront aberrations (HOAs) of the cornea18 and the eye 19 – 21. There have been reports that this procedure reduces low-contrast visual acuity 21 22.…”

mentioning

confidence: 99%