Controlling Astigmatism and Nearsightedness in Developing Youth
David Bartels, O.D., Peter E. Wilcox, O.D.
The progressive worsening of myopia and/or astigmatic refractive errors is a serious concern for
both the child and their parents. The treatment procedure known as orthokeratology has been
shown to slow the rate of progression in children. This study attempted to replicate these findings.
The “No-mold” retrospective refractive data from 20 children (40 eyes) who subsequently chose
orthokeratology treatment were obtained from patient records. The duration of refractive data
varied from as little as 2 to as much as 82 months.
The “Molded” phase included 28 children (56 eyes). Baseline data included refraction,
Simulated K (Sim K) and topographic maps. They were fit with Wave custom designed
orthokeratology mold lenses. Treatment duration was 7 to 57 months.
The “Unmolded” phase involved discontinuing orthokeratology treatment until flat Sim K
returned to within 1D of pre treatment or 14 days.
The mean change in spherical equivalent refractive error (SEQ) during the No-mold phase was -
.37D per year. The mean change in SEQ during the Molded/Unmolded phase was -.03 D per year.
Orthokeratology treatment does slow the progression of myopia in children.
he worsening of myopic and/or astigmatic refractive errors is a serious concern for both the
affected child and their parents. Typical solutions include the use of spectacles and/or
T contact lenses. Neither of these choices addresses the concern surrounding progressive
changes in refractive error but, in fairness to the clinician, there are few good options to present
which work simply and predictably. There are many factors which are associated with these shifts
in myopic refractive error such as: genetics (1, 2, 3), phoria (4, 5), near vision demands (6, 7),
ethnicity (8, 9), sex (10) and younger age (11).
Options to slow the progression in refractive error are unpredictable and at times inconvenient.
Atropinization (12, 13) is one of the most successful forms of intervention but the side effects
greatly outweigh the outcomes. Bifocals and progressive addition lenses have some effect (3, 14,)
but they are cumbersome for youth with active lifestyles. Daytime wearing of rigid gas permeable
lenses has been shown to slightly reduce the progression but at rates which are of limited value to
the patient (15, 16).
An effective, predictable and reproducible method to reduce the rate of change of myopia and
astigmatism is Orthokeratology (also known as Corneal Molding (CM), Corneal Reshaping,
Corneal Refractive Therapy, Advanced Orthokeratology and Custom Accelerated Orthokeratology
to name a few). Orthokeratology employs the nightly wearing of rigid gas permeable lenses
(corneal molds) which reshape the curvatures of the cornea and provides great unaided vision
during waking hours.
Several studies have demonstrated the effectiveness of orthokeratology. The Loric Study (20)
followed patients over 12 months and concluded that Orthokeratology has a positive effect on
slowing the progression of nearsightedness and astigmatism. The Orthokeratology and Adolescent
Myopia Control study (21), a 3 year retrospective study, found that those who participated in
orthokeratology had an average increase in myopia of only -0.67D over three years versus the
expected -1.50D of change over the same period of time. In 2007, Gerowitz, Eiden and Davis
initiated a similar FDA approved, 5 year corneal molding – myopia control study of 300 youths
ages 8 through 14. The outcome is pending.
This study was designed to replicate the findings that orthokeratology slows the normal
progression of myopia/astigmatism.
The study enrolled 28 youth. Seven were male and 21 were female. Age ranged from 4 to 20
years. Age at commencement of orthokeratology treatment ranged between 9 and 16 years.
Subjects’ ethnicities were 27 Caucasians and 1 African-American. Subjects’ pretreatment refractive
error ranged from sphere of -1.00DS to -5.25DS (mean = -2.33D) and cylinder of plano to -1.00
(mean = 0.17DC). Mean SEQ was -2.25D.
No Mold Phase: Historical refractive data were obtained from a subset of 20 subjects of the
study group (40 eyes). They were established patients with active medical charts but had not yet
begun orthokeratology treatment.
The rate of progression of their myopia during this phase was calculated as the difference
between the SEQ at their first visit to the office and the SEQ just prior to initiating orthokeratology
Mold Phase: This phase included all 28 youth (56 eyes). Refractive data prior to
orthokeratology treatment were as follows: mean SEQ = -2.25D (range -1.00 to -5.50), mean sphere
= -2.23D (range -1.00 to -5.25), mean cylinder = 0.17DC (range plano to
Upon choosing orthokeratology, baseline data were collected which included a noncycloplegic
refraction, topography (Scout-Eyequip), intraocular pressure and age of parents’ onset of
The corneal molding lenses were custom designed using the captured topography maps and
Wave Software System. .
The dispensing visit consisted of educating the patient on the wear, insertion and removal
processes and care of the lenses. A variety of care regimens were prescribed based on clinical
judgment. These included Optimum and Boston cleaning and rewetting systems, Sauflon peroxide
system, Allergan rewetting products and lens cleaning sponges. Following the training, unaided
vision was measured. Then the patient was allowed to recline, closing their eyes for 30 minutes.
Immediately upon opening their eyes, acuities were measured and the fit was assessed with white
light and NaFl. The molds were removed and topographies and unaided acuities were measured.
Though all patients initially wore their molds every night, the lens wearing schedule eventually
varied among the 28 subjects: Seven wore the lenses every night, 18 wore them every second night
and 3 wore then every third night. This schedule was determined by the patient and their desired
Follow up visits included one-week, one-month, three months and six months as determined by
the investigators. On rare occasion, a mold lens was changed to improve fit or post wear acuity.
The treatment was considered successful if at the 3 month visit, the patient was “20/happy”,
topography was homogenous and no corneal pathology was observed. The duration of
orthokeratology treatment varied per subject ranging from 7 to 57 months.
Unmold Phase: Given the clinical nature of this study and inconvenience to the patient,
whenever possible, an effort was made to correlate discontinuing lens wear with any unscheduled
mold lens replacement (lost or broken). Otherwise, patients complied with the request to unmold.
Lens wear was discontinued and unmolding was considered complete when a subject’s flat
Simulated-K returned to within 1.00D of their Sim K prior to molding or 14 days had elapsed since
discontinuing lens wear. During the unmolding process, noncycloplegic refractions were performed
at 3 to 7 day intervals until reversal was complete.
The rate of progression of myopia for the molded patients was calculated as the difference
between the SEQ just prior to molding and the SEQ after unmolding was complete.
Results for all phases are presented in Figure 1. Figure 1 superimposes both the No Mold and
Molded/Unmolded phase data. The X axis represents the duration of the phases in months.
No Mold Phase:
This phase included the subset of 20 established patients (40 eyes). The mean change in SEQ
showed a progression of -0.37D per year. This is represented in Figure 1 by the blue data diamonds
and blue trend line.
This phase included all 28 subjects (56 eyes).
The reversal requirement was achieved by 27 of 28 subjects within two weeks (within 1D of
pretreatment Sims K). In fact 44 of 54 eyes were within .5D of Sim K and 49 of 54 eyes were
within .75D of original Sim K. Only 1 subject failed and was excluded from the study.
During the mold to unmold phase, the mean SEQ progression rate was only -0.03D per year.
This is represented in Figure 1 by the magenta data squares and magenta trend line. Some data
points are superimposed due to duplicate results on some patients. Progression rates were calculated
from the raw data, not the displayed graph.
Figure 1. Myopic Progression during No Mold and Unmolded after Molding Phases
Unmolded after Molding
Unmolded after Molding
The CANDY study demonstrated that Orthokeratology does both significantly reduce and even
stop the rate of change of nearsightedness and astigmatism in developing youth (ages 9-18). This
effect was independent of the age of initiation of orthokeratology and the premolding refractive
This reduction in the rate of change occurs for youth in all the familial risk groups (neither, one
or both parents myopic by age 18).
The IOP had no effect on myopic progression.
The CANDY study attempted to determine if orthokeratology halted refractive error change or
simply masks the change due to the molding of the corneal surface. By unmolding the treatment
and allowing the Sim K’s to return to baseline levels, we believe some progress has been made to
answer this question. The CANDY subjects had an average premolding progression in their SEQ
of- 0.37D per year. This rate of progression in myopic children is coincident with published
literature (11). These subjects’ SEQ was essentially halted during the duration of their molding to
an impressive mean rate of -.03D per year after being unmolded.
There is some concern that the 2 week duration of the reversal phase was insufficient despite the
fact that the Sim Ks of 49 of the 54 subjects were within .75D of their baseline Sim K’s. This issue
should be the basis for further study. Data obtained from trials using longer reversal periods would
provide more complete data.
Though Hyman, Marsh-Tootle et.al (COMET 2005) showed that there is a greater progression in
myopic SEQ in their 6 to 7 year old age group and a slowing in the rate of progression by their
oldest age grouping (10 to 11 years), there was progression in all the populations they followed.
When the CANDY study reviewed the age of those molded, from 9 years to 18 years, essentially no
correlation between age and progression of SEQ was found.
Since the CANDY study was initiated by evaluating patients who had previously established
various wearing schedules of their corneal molds, other interesting conclusions surfaced. Some
patients did not need to wear their molds every night to achieve visual success yet they had the
same myopia/astigmatism stabilization. The patients who were best suited to sleep in their molds
only every second to third night were those with lower refractive errors and steeper Sim K’s. For
this reason the authors submit that there is a greater incentive to mold the younger eye at lower
refractive errors. Clinicians should present to the higher risk/lower SEQ patients and their family
1.) orthokeratology when done in the early stages of myopia is more cost effective,
2.) because their SEQ is low, it allows the child to wear the lenses every other night
3.) it is more acceptable for a younger patient to experience any partial unmolding during the
alternate days when the lenses were not worn
4) it is better to stop axial elongation when the eye is still shorter, reducing the risk of retinal
The population of eligible patients in this study was significantly skewed toward a white
population (27 White, 1 Black, 0 Hispanic and 0 Asians). As it has been shown that there is a
greater incidence of and progression of SEQ in the Asian populations (19), a similar study within a
primarily Asian population would be even more powerful.
The CANDY study was designed to investigate if orthokeratology slows the progression of
myopia (with or without astigmatism). The study was not designed to investigate how specifically
designed corneal molds affect the eye/vision. Additionally, the goal of each patient was to have
good vision (with and without the molds), good fit and good comfort; hence, liberal boundaries
were granted on the complicated designs of the reverse geometry lenses. All designs were similar in
they were tied to the global goals of success. An evaluation of the various designs does reveal more
similarities than differences among the molds.
Despite the repeatable results of ‘myopia control’ by orthokeratology, some caution should be
exercised in promoting this as a predictable way to halt the refractive error changes. Not all studies
have found such consistent reduction in refractive error progression (Reim 2003). One of the
limitations of this study is size of population. Larger, well controlled trials are needed to further
validate the findings of this and other orthokeratology studies.
The investigators continue to monitor all those in the Candy study and are expanding their
centers while broadening the data base. Additional variables which may be monitored are central
corneal epithelial thicknesses and total central corneal thickness and axial length. They look
forward to presenting their future findings.
About the authors:
Dr. Peter E. Wilcox is in solo private practice in Hayes, Virginia. He received his OD from
UAB and attended a Residency at PCO.
Dr. David Bartels is in group practice in Buffalo, NY. He received his OD at ICO.
The authors would like to extend their gratitude to Caroline Guerrero Cauchi, O.D., F.O.A.A.
and Richard Anderson, O.D., F.O.A.A. for their editorial assistance in preparing this article.
On a personal note, being one of the investigators and the father of two of the subjects, I am
pleasantly surprised at the outcome of the study. My daughter and son both mold every 72 hours.
They have been threatened with myopic progression if they don’t mold more often, only to fall on
deaf ears. I don’t know the correct number of nights needed to hold the progression back but both
my children are doing fine. Corneal Molding has become the norm in my family and it is very
gratifying to observe no change in my children’s vision over many years. David Bartels OD.
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