Longitudinal changes in the ganglion cell-inner plexiform layer thickness in high myopia: a prospective observational study

Abstract

Aim To determine longitudinal changes of the ganglion cell-inner plexiform layer (GC-IPL) thickness in patients with high myopia. Methods The subjects were divided into two groups: a high myopia group (axial length >= 26.0 mm) and a normal control group. Both groups were divided into subgroups based on age (decade): 20s, 30s, 40s and 50s. Twenty eyes were included in each subgroup. After the initial visit, GC-IPL thicknesses were measured three more times with at least a 1-year interval between examinations using spectral domain optical coherence tomography. The average GC-IPL thickness was fitted with linear mixed models. Results The average GC-IPL thickness at the first visit was 78.50 +/- 8.79 mu m and 84.29 +/- 6.12 mu m in the high myopia and control groups, respectively. In both groups, the average GC-IPL thickness showed a significant change over time. The rate of GC-IPL reduction in individuals aged in their 50s, 40s, 30s and 20s with high myopia were -0.81 mu m/year,-0.51 mu m/year, -0.28 mu m/year and -0.12 mu m/year, respectively, and in controls in their 50s, 40s, 30s and 20s, they were -0.31 mu m/year,-0.25 mu m/year, -0.12 mu m/year and -0.02 mu m/year, respectively. Additionally, individuals aged in their 50s showed a statistically significant interaction between group and duration (p<0.001). Conclusions Highly myopic eyes had thinner GC-IPL and a significantly greater reduction in GC-IPL over 3 years when compared with normal eyes. Additionally, the reduction rate of the GC-IPL thickness was greater in older patients in both groups, which was more prominent in the high myopia group.