Longitudinal Changes in Peripapillary Retinal Nerve Fiber Layer Thickness in High Myopia: A Prospective, Observational Study.

Purpose: To determine longitudinal change of peripapillary retinal nerve fiber layer (pRNFL) thickness in patients with high myopia without ophthalmic disease.

Design: Prospective observational study.

Participants: Participants were divided into 2 groups: a high myopia group (80 eyes) that included eyes with an axial length ≥26.0 mm and a control group (80 eyes) that included eyes with a spherical equivalent (SE) between +3.0 and -6.0 diopters (D). Both groups were further divided into age subgroups by decade: 20s, 30s, 40s, and 50s. Each subgroup included 20 eyes.

Methods: After the initial visit, pRNFL thickness measurements were performed 2 times more with at least 1-year intervals between examinations using spectral-domain OCT. The mean pRNFL thickness was fitted with linear mixed models.

Main Outcome Measures: The pRNFL thickness and rate of pRNFL thickness reduction.

Results: The mean patient age and thickness of the pRNFL at the first visit were 39.5±12.5 years and 90.16±9.06 μm, and 41.5±12.2 years and 96.80±9.50 μm in the high myopia and control groups, respectively. The high myopia group showed a significant reduction in mean pRNFL thickness between the first and second visits, and between the second and third visits (P < 0.001 and P = 0.002, respectively). For individuals aged 50 to 59 years, the reduction rate was -1.69 and -0.63 μm/year in the high myopia and control groups, respectively; the interaction between group and duration was significant (P = 0.014). The reduction rate in individuals aged 40 to 49 years was -1.70 and -0.48 μm/year in the 2 groups, respectively; the interaction was also significant (P = 0.031). Among those aged 30 to 39 years and 20 to 29 years, no such significant interactions were observed (-0.95 vs. -0.57 μm/year, P = 0.086 and -0.31 vs. -0.19 μm/year, P = 0.858, respectively).

Conclusions: Highly myopic eyes had a significantly greater decrease in pRNFL over 2 years than normal eyes. In addition, the reduction rate of pRNFL thickness was greater in older patients with high myopia, whereas similar values were shown in normal controls except individuals aged 20 to 29 years.