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 µm and 84.29 ± 6.12 µm 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 µm/year,–0.51 µm/year, −0.28 µm/year and −0.12 µm/year, respectively, and in controls in their 50s, 40s, 30s and 20s, they were −0.31 µm/year,–0.25 µm/year, −0.12 µm/year and −0.02 µm/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.