Describe axial elongation using 14-year longitudinal data in a large, ethnically diverse group of myopic children, estimate age and axial length (AL) at stabilization, and evaluate associations between the progression and stabilization of AL and myopia.
Axial length was measured by A-scan ultrasonography annually. Axial length data were fit with individual polynomial functions and curve-based parameters (AL at stabilization and age at stabilization when annual rate of axial elongation ≤0.06 mm) were estimated. For myopia progression, noncycloplegic spherical equivalent refractions were fit with Gompertz functions.
Four hundred thirty-one participants, with AL and myopia data fit successfully, were classified into four cohorts: Younger (n=30); Older (n=334); AL Stabilized at Baseline (n=19); and AL Not Stabilized (n=48). At AL stabilization, for participants in the Younger and Older Cohorts, mean (SD) age and AL were 16.3 (2.4) years and 25.2 (0.9) mm, respectively. No associations were found between age at AL stabilization and ethnicity, sex, or number of myopic parents. At stabilization, sex and number of myopic parents (both P<0.003), but not ethnicity, were significantly associated with AL. Axial length and myopia progression curves were highly correlated overall (all r>0.77, P<0.0001). However, unlike AL, the amount of myopia did not differ significantly between males and females.
In most of the participants, AL increased rapidly at younger ages and then slowed and stabilized. The close association between growth and stabilization of AL and myopia is consistent with the suggestion that axial elongation is the primary ocular component in myopia progression and stabilization.
Department of Family, Population and Preventive Medicine (W.H.), Stony Brook University, Stony Brook, NY; Department of Optometry and Vision Science (T.T.N.), School of Optometry, University of Alabama at Birmingham, Birmingham, AL; Wills Eye Hospital (L.H.), Ophthalmology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA; and New England College of Optometry (J.G.), Boston, MA.
Address correspondence to Wei Hou, Ph.D., Department of Family, Population and Preventive Medicine, Stony Brook University, Health Sciences Center, L3-086 Room 105, Stony Brook, New York 11794-8036; e-mail: firstname.lastname@example.org
The authors have no funding or conflicts of interest to disclose.
Supported by NEI/NIH grants EY11740, 11805, 11756, 11754, 11752, and 11755.
COMET Group members are listed in the Appendix 1.
Accepted February 25, 2018