Orthokeratology proved reversible in a study, with refraction and visual
acuity returning to baseline levels 1 week after the treatment was completed.
The study was the first to show the effects of orthokeratology to be
reversible after 1 year of treatment, Takahiro Hiraoka, MD, PhD, said in an
e-mail interview with Ocular Surgery News.
“The most important finding of our study is 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,” Dr.
Orthokeratology is a nonsurgical procedure in which hard contact lenses
worn during sleep reduce refractive error and improve visual quality,
particularly in low to moderately myopic patients who desire independence from
glasses or contact lenses. The procedure is considered a viable alternative to
LASIK and PRK, the study authors said in the British Journal of
Indications for orthokeratology include low myopia of up to –4 D
without astigmatism. Contraindications include keratoconus, corneal disease and
severe dry eye. However, orthokeratology may be performed in the presence of
mild dry eye, Dr. Hiraoka said.
topography shows decentered treatment during orthokeratology treatment for
|The anterior segment after fluorescein staining during
|Anterior segment optical coherence tomography imaging during
orthokeratology. Arrows point to the space between the hard contact lens and
cornea, called the tear reservoir zone. |
topography after successful orthokeratology confirms a flatter central
Images: Hiraoka T
Assessment and treatment
The prospective study included 46 eyes of 23 patients. Inclusion
criteria were manifest spherical equivalent refraction between –4 D and
–1 D, refractive astigmatism up to 1 D, best corrected visual acuity of
20/20 or better, mean keratometry between 40 D and 46.25 D, no previous
orthokeratology and subjects 20 to 37 years old.
Patients with ocular or corneal pathology, history of ocular disease or
previous ocular surgery and systemic diseases such as diabetes mellitus were
excluded. Orthokeratology was conducted with four-zone reverse geometry contact
lenses (Polymer Technology). Patients were directed to wear the lenses for at
least 7 hours nightly for 12 months.
Refraction, corneal topography, wavefront aberrometry, visual acuity and
area under the log contrast sensitivity function were assessed at baseline, 12
months after the start of treatment, and 1 week and 1 month after the
completion of treatment.
Six patients discontinued treatment before 12 months, leaving a final
study group of 34 eyes of 17 patients that completed 1-year follow-up.
Transient effects of orthokeratology
Study data showed that orthokeratology reduced manifest spherical
equivalent refraction from –2.17 D at baseline to –0.17 D at 12
months and improved logMAR uncorrected visual acuity from 0.72 to –0.06.
Both increases were statistically significant (P < .0001). BCVA and
regular astigmatism did not change significantly, the authors said.
However, orthokeratology significantly increased corneal irregular
astigmatism and higher-order aberrations and reduced area under the log
contrast sensitivity function.
“Increases in corneal irregular astigmatism are quite similar to
those in higher-order wavefront aberrations,” Dr. Hiraoka said. “Both
parameters mean the decreases in optical quality of the eye. On the other hand,
reduced low-contrast visual acuity implies the decline in quality of vision.
Therefore, the main declines in optical quality caused by orthokeratology are
corneal irregular astigmatism or higher-order wavefront aberrations.”
All visual and refractive parameters rapidly returned to pretreatment
values after discontinuation of orthokeratology. Corneal irregular astigmatism,
higher-order aberrations and contrast sensitivity function returned to baseline
levels within 1 week after the end of treatment.
“As for the reason why corneal irregular astigmatism, [higher-order
aberrations] and contrast sensitivity recovered more quickly than refractive
error and UCVA, we at present have no clear explanation,” Dr. Hiraoka
said. “But corneal surface contour is considered to recover rapidly after
discontinuation of orthokeratology, as the early recovery of corneal thickness
and curvature was confirmed. Thus, corneal irregular astigmatism, which
reflects subtle changes in corneal surface shape, may have recovered
The findings may prove useful in counseling patients considering LASIK
or PRK, the authors said.
“On the basis of these findings, we can explain to patients that
overnight orthokeratology is a reversible procedure,” they said. “In
addition, the current information concerning each recovery time is quite useful
to consider the starting point of the following procedure, if patients
undergoing orthokeratology hope for another corrective option, such as laser
More research on the recovery of clinical parameters after cessation of
orthokeratology in younger patients is warranted, the authors said. –
by Matt Hasson
- Hiraoka T, Okamoto C, Ishii Y, Okamoto F, Oshika T. Recovery of
corneal irregular astigmatism, ocular higher-order aberrations, and contrast
sensitivity after discontinuation of overnight orthokeratology. Br J
- Takahiro Hiraoka, MD, PhD, can be reached at Department of
Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1
Tennoudai, Tsukuba, Ibaraki 305-8575, Japan; +81-29-853-3148; e-mail:
Hiraoka has no direct financial interest in the products discussed in this
article, nor is he a paid consultant for any companies mentioned.