A Trial of Bifocals in Myopic Children With Esophoria



National Eye Institute (NEI)

Brief Summary

To test the hypothesis that correction with bifocal spectacle lenses rather than
single-vision lenses will slow the progression of myopia in children with near-point
esophoria. The primary outcome variable is cycloplegic refraction as measured with an
automated refractor. Axial length is measured with ultrasound in order to test the corollary
hypothesis that use of bifocals will slow ocular growth in these myopic children. We will
also examine the amount of close work performed by subjects and the degree of parental myopia
as factors that may influence myopia progression.

Detailed Description

About 25 percent of all persons in the United States are myopic. The most common form of
myopia is childhood myopia, which begins after age 6 and progresses rapidly until age 16.
Myopia progression results from excessive growth of the eye, primarily by enlargement of the
vitreous chamber. Excessive elongation of the eye is a major risk factor for retinal

Previous prospective studies failed to show that use of bifocals was effective in slowing
myopia progression. However, these studies did not separate subjects by near-point phoria
before randomization. Retrospective studies by David Goss indicated that bifocals slowed
myopia progression by almost 50 percent in children with near-point esophoria but had no
effect on children with exophoria.

A small, prospective pilot study, completed by the investigators of this trial, also
supported the hypothesis that bifocals slow myopia progression in children with near-point
esophoria. Thirty-two myopic children, all of whom showed near-point esophoria, were enrolled
in this 18-month study. Twenty-eight children completed the study, with 14 randomized into
bifocals and 14 into single-vision lenses. Cycloplegic automated refraction was performed
every 6 months. Over the course of the whole study, there was a small, statistically
insignificant difference in the rates of myopia progression: 0.57 diopters per year (D/yr)
(S.E. = 0.11) for those in single-vision lenses compared with 0.36 D/yr (S.E. = 0.12) for
those in bifocals (p = 0.26).

However, significant seasonal effects in myopia progression were demonstrated, and the
results also suggested that the beneficial effects of bifocals may take several months to
develop. During the first 6 months, which included most of the school year, myopia
progression was rapid in both the bifocal group (0.61 D/yr) and the single-vision group (0.68
D/yr). During the second 6 months, which included all of the summer vacation, myopia
progression was slow in both groups, 0.32 and 0.26 D/yr for bifocal wearers and single-vision
wearers, respectively. During the last 6 months, i.e., the second school year, myopia
progressed slowly in the bifocal wearers (0.37 D/yr) but rapidly (0.80 D/yr) in single-vision
wearers. A repeated-measure analysis of variance demonstrated a significant seasonal effect
(p < 0.002) and a significant interaction between season and type of correction (p < 0.043).

The apparent effectiveness of bifocals in children with near-point esophoria and the lack of
effectiveness in other children may be explained by a greater lag of accommodation in
children with esophoria. This lag might cause a slightly blurred retinal image that the
bifocal may sharpen. Other mechanisms might also be involved.

Eighty or more myopic children, all with near-point esophoria as measured at baseline with
von Graefe prisms through a current myopic correction placed in a phoropter, will be randomly
assigned to wear either single-vision spectacle lenses or lenses with +1.50 D add in a
flat-top 28-mm segment. Subjects will visit one of two sites, either a private optometry
practice in Tulsa or the optometry clinic at Northeastern State University, every 6 months.
Data collected at each visit will include automated refraction after cycloplegia with 1
percent tropicamide, biometry with A-scan, and estimates of the amount of study and other
close work by means of questionnaires administered to the subjects and their parents. We will
also obtain measures of the degree of myopia in the biological parents. The myopic correction
will be changed if the spherical component of the refraction in either eye has changed by 0.5
diopter or more or if any change in cylinder power or axis improves vision in either eye by
three letters or more. The study will continue for 30 months and will include six visits by
each subject.

Overall Status

Unknown status

Start Date


Completion Date


Primary Completion Date



Phase 3

Study Type




Intervention Type


Intervention Name



Boys must have been between 6 and 12 years of age; girls between 6 and 11 years of age. All
children must have had at least 0.5 diopters of myopia in both eyes, near-point esophoria,
at least 20/25 acuity in each eye, and 40 seconds of stereopsis and must have been free of
ocular disease or systemic disease that may have altered refraction. All subjects were
willing to wear bifocal spectacle lenses for 30 months.



Minimum Age

6 Years

Maximum Age

12 Years

Verification Date


Lastchanged Date


Firstreceived Date



Has Expanded Access


Condition Browse

Firstreceived Results Date




Fulk GW, Cyert LA. Can bifocals slow myopia progression? J Am Optom Assoc. 1996 Dec;67(12):749-54.




Fulk GW; Cyert LA; Parker DE; A 3-year clinical trial of bifocals to slow myopia progression in children with near-point esophoria: Baseline characteristics., Invest Ophthalmol Vis Sci 1997;38(4):S1158


Fulk GW, Cyert LA, Parker DE. A randomized trial of the effect of single-vision vs. bifocal lenses on myopia progression in children with esophoria. Optom Vis Sci. 2000 Aug;77(8):395-401.



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

June 23, 2005

Last Update Submitted Qc

June 23, 2005

Last Update Posted

June 24, 2005

Last Known Status

Active, not recruiting

ClinicalTrials.gov processed this data on August 24, 2018


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Study Phase

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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.

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