Article

Effectiveness of Bifocal Control ofChildhood Myopia Progression as

a Function of Near Point Phoria

and Binocular Cross-Cylinder

David A. Goss, OD, PhD, F AAOEdward F. Uyesugi, OD

Records of 285 patients with myopia from six optometry practiceswere used to examine retrospectively the factors affecting the efficacy ofbifocal lenses used to control progression of childhood myopia. Rates ofprogression in diopters per year (D/yr) were calculated from four or morerefractions between the ages of 6 and 15 years. Near point phoria wasrelated to the effectiveness of bifocal control of myopia progression, butbinocular cross-cylinder findings, gender, and plot category (an index ofthe amount of myopia at the initial examination and presumably relatedto age at onset of myopia) were not. The rates of progression for childrenwith near point esophoria were -0.33 D/yr (n = 66; SD = 0.20) withbifocals and -0.59 D/yr (n = 52; SD = 0.32) with single-vision lenses.The difference in means was significantly different (P < .000002). Therate was lower with bifocals regardless of the binocular cross-cylindergrouping, gender, or plot category. Rates of myopia progression were notsignificantly different with bifocals or single-vision lenses for childrenwith orthophoria and exophoria. Key Words: Bifocal lenses, binocularcross-cylinder, esophoria, myopia.

INTRODUCTION

One method used for many years by op-tometrists to slow progression of childhoodmyopia was the prescription of bifocal lenses.A reviewl of the articles on bifocal control ofmyopia reveals that the success reportedranges from being very good in some studies tohaving little or no effect in others.

Some studies suggested that the effective-ness of bifocals in slowing progression of child-

Correspondence regarding this article should beaddressed to Dr. David A. Goss, School of Optom-etry, Indiana University, Bloomington, IN 47405.

12 Journal of Optometric Vision Development

hood myopia may be related to particularocular or visual characteristics. Three stud-ies2-5 found reduced rates of myopia progres-sion in children with near point esophoria asmeasured by the von Graefe prism dissocia-tion method. Bifocals did not decrease the rateof progression in children with orthophoria orexophoria at near. Roberts and Banford2.3found reduced progression rates for childrenwith more plus on the 14B net as calculatedby the Optometric Extension Program (OEP)formulas. A study by Goss4 found a lowerprogression rate in cases where the nearpoint binocular cross-cylinder test showedhigher amounts of plus over the distance-