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Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology

 iGO SUMMARY: This small Japanese study evaluated what happened to 17 short-sighted individuals who had undergone Overnight Vision Correction (OVC) treatment and subsequently worn overnight ortho-k corrective contact lenses for a year but then discontinued OVC lens wear. The results revealed that the level of short-sightedness and all other eye-related factors for all 17 individuals returned to the pre-treatment level within one week of discontinuing OVC lens wear. This demonstrates that OVC is a completely reversible treatment.
 
ABSTRACT
AIMS: To examine prospectively the recovery of various parameters after discontinuation of overnight orthokeratology.
 

METHODS: Seventeen subjects undergoing orthokeratology for 12 months were examined. Refraction, corneal topography, wavefront aberrometry, a visual acuity test and a contrast sensitivity test were performed at baseline, 12 months after commencement of the procedure, and 1 week and 1 month after discontinuation of the treatment. Asymmetry and higher-order irregularity components were calculated using a Fourier analysis of the corneal topography data. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated.

RESULTS: Orthokeratology significantly reduced manifest refraction (p<0.0001, Dunnett test) and significantly improved uncorrected visual acuity (UCVA) at 12 months after commencement of the procedure (p<0.0001). Asymmetry and higher-order irregularity components increased significantly (p<0.0001, p = 0.0032, respectively), and third- and fourth-order aberrations also increased significantly (p<0.0001). The treatment resulted in significant decreases in AULCSF (p = 0.0004). After discontinuing lens wear, all parameters, such as refraction, UCVA, asymmetry, higher-order irregularity, third-order aberration, fourth-order aberration and AULCSF, returned to the baseline level at 1 week.

CONCLUSION: This study confirmed that the effect of orthokeratology is completely reversible in light of optical quality of the eye and quality of vision as well as refraction and visual acuity.

February 2009, British Journal of Ophthalmology,T Hiraoka, C Okamoto, Y Ishii, F Okamoto, T Oshika+ Author Affiliations, Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan

For full article go to: British Journal of Optometry 

 

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