Abstract
Purpose :
Emmetropic eyes show ‘physiologic’ eye growth, an ongoing elongation of the eye during childhood and teenage years in the absence of substantial refractive change, attributable to loss of crystalline lens power. It has been hypothesized that a proportion of growth in myopic eyes is also physiologic and not directly linked to refractive progression. However, Mutti et al (OVS, 2012;89:251) among others have reported that lens thinning ceases rather abruptly during myopia onset, raising the question of the existence of this component of growth in myopes in the absence of significant changes to corneal curvature.
Methods :
Subject data were drawn from control groups described in Cheng et al (Acta Ophthalmol 2020:98:e346). Changes in spherical equivalent cycloplegic autorefraction (ΔSECAR; WAM-5500) and axial length (ΔAL; IOLMaster) were available for untreated right eyes of myopes aged 8 to 11 years at one (N= 151) and two (N= 99) years follow-up. Total least squares regression was performed across feasible values of λ (ratio of the measurement variance of ΔSECAR to that of ΔAL). The intercept of the regression line when ΔSECAR was equal to zero was taken to be physiological eye growth (figure 1). 95% CIs for this intercept were obtained by bootstrapping.
Results :
The results were sensitive to λ, but even in the extreme case of 1/λ = 0, the lower limit of the 95% CI was greater than zero, providing evidence for existence of physiologic growth in myopes (figure 2). No consistent change in physiological eye growth across age was detected within this group. Gradients relating ΔSECAR to ΔAL match expectations from optical calculations.
Conclusions :
This analysis supports the existence of physiological eye growth in myopic children. Estimated size of physiological growth at 1- and 2- years seems to be less than that reported for emmetropes.
This is a 2021 ARVO Annual Meeting abstract.