Overnight wear of gas permeable contact lenses specially designed for corneal refractive therapy (CRT) can reduce farsightedness, according to a new study.

CRT, like orthokeratology (ortho-k), is the use of specially designed gas permeable (GP) contacts to alter the shape of the cornea and thereby temporarily reduce or eliminate refractive error. The GP lenses are worn overnight during sleep, to produce clear vision without glasses or contacts during the day. Read more…

The front surface of the eye returns to its original shape relatively quickly after discontinuation of overnight orthokeratology, according to a study published in the British Journal of Ophthalmology. 

Researchers in Japan conducted the study to investigate the reversibility of the orthokeratology procedure used for the temporary non-surgical correction of myopia. The procedure, also called “ortho-k,” reshapes the cornea (the front surface of the eye) with specially designed rigid gas permeable contact lenses worn during sleep.

The prospective study followed 17 subjects who underwent the ortho-k procedure for a period of 12 months. 

Prior to the procedure, several baseline eye measurements were taken, including refraction, corneal topography, wavefront aberrometry, uncorrected visual acuity (UCVA) and contrast sensitivity. These tests were then repeated 12 months after commencement of ortho-k, and one week and one month after discontinuation of the procedure.

The researchers found that all measures of corneal shape, refractive error and visual performance returned to baseline levels within one week of discontinuation of overnight ortho-k.

They concluded the effects of orthokeratology are completely reversible, and that the cornea fully recovers its original parameters relatively quickly after ortho-k is discontinued.

Source: Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology. British Journal of Ophthalmology. February 2009.