The Berkeley Orthokeratology Study



National Eye Institute (NEI)

Brief Summary

To evaluate the relative efficacy of orthokeratology, primarily by assessment of changes in
central corneal thickness, astigmatism, visual acuity, endothelial cell density, and corneal

To evaluate the relative safety of orthokeratology, primarily by assessment of changes in
central corneal thickness, astigmatism, visual acuity, endothelial cell density, induced
corneal edema, and epithelial staining.

To assess the duration of any orthokeratology treatment effect.

To study the mechanisms by which refractive error and visual acuity changes occur, in
particular the contribution that comes from changes in corneal curvature and shape.

To determine whether there were any predisposing ocular factors that could be used to predict
which subjects will experience changes or complications.

Detailed Description

In the early 1960s, a group of clinicians asserted that myopia could be reduced and possibly
corrected by fitting specially designed contact lenses to induce corneal flattening and
thereby reduce the refractive power of the eye. This technique, known as orthokeratology,
required that the lenses be fitted and then changed progressively until vision becomes normal
or nearly normal. Advocates of orthokeratology claimed that corneal changes could be induced
in a predictable fashion, were often permanent, and occurred without causing any adverse
effects to the cornea. Data on orthokeratology were generally limited, poorly documented, and
did not address the issues of control or failure.

The Berkeley Orthokeratology Study was a single center randomized, concurrently controlled,
masked clinical trial. Corneal and visual changes in an orthokeratology treatment group were
monitored and compared with those observed in a control group whose members wore contact
lenses fitted in a standard clinical manner. Visual and ocular characteristics were monitored
for 1.5 years.

Eighty subjects were studied-40 in an orthokeratology group and 40 in a control group fitted
with conventional hard contact lenses. The hard lenses chosen for this study were made of
either polymethyl methacrylate (PMMA) or a PMMA-silicone combination (Polycon). All subjects
were initially fitted with PMMA lenses.

The initial treatment and control lenses were selected according to protocol guidelines and
then adjusted to achieve an "optimal fit" based on lens position, movement, and alignment as
assessed by fluorescein study. At the outset, the treatment and control lenses differed in
that the treatment lenses were on the average thicker and flatter and had a larger diameter.

Following the dispensing visit, subjects progressed through three study phases. In the
adaption phase (Phase A), subjects were examined weekly until they were adapted to 12 to 14
hours of daily contact lens wear. The postadaptive phase (Phase B) consisted of monthly
followup examinations for 1 year. The final phase (Phase C) consisted of a lens withdrawal
segment and a postwearing segment.

Overall Status


Start Date


Completion Date


Primary Completion Date



Phase 3

Study Type




Intervention Type


Intervention Name

Intervention Type


Intervention Name



Myopic volunteers, ages 20 to 35, who had not worn contact lenses were eligible to
participate in the study if they were free of ocular disease, were in good physical health,
and were not taking systemic medications that could have ocular side effects. In addition,
eligibility was limited to persons with corneal curvature between 40.50 and 47.00 D
(flatter keratometry reading), corrected visual acuity of 6/6 (20/20) or better in each
eye, astigmatism less than 0.75 D, anisometropia less than 1 D, and myopia between 1 and 4



Minimum Age

20 Years

Maximum Age

35 Years

Verification Date


Lastchanged Date


Firstreceived Date


Has Expanded Access


Condition Browse

Intervention Browse

Mesh Term

Polymethyl Methacrylate

Firstreceived Results Date




Polse KA, Brand RJ. Contact lens effects on ametropia: a current example of the clinical trial. Am J Optom Physiol Opt. 1981 Apr;58(4):281-8.




Brand RJ, Polse KA, Schwalbe JS. The Berkeley Orthokeratology Study, Part I: General conduct of the study. Am J Optom Physiol Opt. 1983 Mar;60(3):175-86.




Polse KA, Brand RJ, Keener RJ, Schwalbe JS, Vastine DW. The Berkeley Orthokeratology Study, part III: safety. Am J Optom Physiol Opt. 1983 Apr;60(4):321-8.




Polse KA, Brand RJ, Schwalbe JS, Vastine DW, Keener RJ. The Berkeley Orthokeratology Study, Part II: Efficacy and duration. Am J Optom Physiol Opt. 1983 Mar;60(3):187-98.




Polse KA, Brand RJ, Vastine DW, Schwalbe JS. Corneal change accompanying orthokeratology. Plastic or elastic? Results of a randomized controlled clinical trial. Arch Ophthalmol. 1983 Dec;101(12):1873-8.



Firstreceived Results Disposition Date


Study Design Info



Primary Purpose




Study First Submitted

September 23, 1999

Study First Submitted Qc

September 23, 1999

Study First Posted

September 24, 1999

Last Update Submitted

September 16, 2009

Last Update Submitted Qc

September 16, 2009

Last Update Posted

September 17, 2009 processed this data on August 24, 2018


Conditions usually refer to a disease, disorder, syndrome, illness, or injury. In, conditions include any health issue worth studying, such as lifespan, quality of life, health risks, etc.

Interventions refer to the drug, vaccine, procedure, device, or other potential treatment being studied. Interventions can also include less intrusive possibilities such as surveys, education, and interviews.
Study Phase

Most clinical trials are designated as phase 1, 2, 3, or 4, based on the type of questions that study is seeking to answer:

In Phase 1 (Phase I) clinical trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.

In Phase 2 (Phase II) clinical trials, the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.

In Phase 3 (Phase III) clinical trials, the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.

In Phase 4 (Phase IV) clinical trials, post marketing studies delineate additional information including the drug's risks, benefits, and optimal use.

These phases are defined by the Food and Drug Administration in the Code of Federal Regulations.

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