Orthokeratology, or “ortho-k,” is the fitting of specially designed gas permeable contact lenses that are worn during sleep to reduce or eliminate myopia without surgery.
Ortho-k is an alternative to LASIK surgery for nearsighted individuals who want to see clearly without glasses or contacts and are too young for laser vision correction or for some other reason are not good candidates for refractive eye surgery.
Researchers in Japan recently evaluated the reversibility of orthokeratology. Reversibility is desirable, as teenagers who undergo ortho-k may want to have LASIK surgery later, and it is important for eyes undergoing laser vision correction to be healthy and have a stable refractive error. Also, the researchers wanted to know if ortho-k causes any long-term loss of best-corrected visual acuity after the treatment is discontinued.
The study evaluated 17 nearsighted subjects who underwent ortho-k for a period of 12 months. The following measurements were taken prior to ortho-k, 12 months after commencement of the procedure, and one week and one month after ortho-k was discontinued:
- Refractive error
- Corneal topography
- Wavefront aberrometry to evaluate higher-order aberrations
- Visual acuity with a standard eye chart
- Contrast sensitivity
The study showed that after one week of discontinuing wear of the ortho-k lenses, all measurements returned to the pre-treatment levels. The researchers concluded that orthokeratology is completely reversible, as determined by measurements of corneal shape, refractive error, visual acuity and quality of vision.
Source: Recovery of corneal irregular astigmatism, ocular higher-order aberrations and contrast sensitivity after discontinuation of overnight orthokeratology. British Journal of Ophthalmology. February 2009.
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