Purpose: To determine the relationship between accommodative lag and rate of myopia progression when Ghanaian myopic school children are either undercorrected or fully corrected with single vision lenses.
Methods: A 2-year single masked randomized control trial was conducted using 150 Ghanaian myopic children aged 10 to 15 years with mean baseline myopia of -1.98 ± 0.50D. The children were randomly assigned to wear either a full correction (n = 75) or +0.50D undercorrection (UC) (n = 75) single vision lenses. Repeated measurements which included refractive error and accommodative response at 33 and 28.6 cm for FC and UC, respectively, were performed using Open-Field Autorefractor whereas ocular biometry results were obtained using A-Scan ultrasonography. Results were based on the right eye and analyzed using STATA 11.
Results: After 24 months, the mean myopia progression of children in the FC group (-0.54 ± 0.26D) was not significantly different from that of the children in the UC group (-0.5 ± 0.22D) (p = 0.31). There was no significant difference between the mean values of the initial near lag and the average lag measured 24 months later in both groups (FC: initial lag -0.74 ± 0.17D, average lag -0.72 ± 0.15D, p = 0.44; UC: initial lag -0.57 ± 0.14D, average lag -0.58 ± 0.15D; p = 0.67). Also, there was no significant correlation between refractive change seen in 24 months and either the first near lag for both FC (r = -0.05, p = 0.43) and UC (r = -0.08, p = 0.43) or the average near lag of accommodation for both FC (r = -0.02, p = 0.49) and UC (r = -0.04, p = 0.49).
Conclusions: This study showed no relationship between lag of accommodation and rate of myopia progression in children with progressing myopia. Different ethnic groups may respond differently to the same size of hyperopic blur.