Enlarged Blind Spot Linked to Gamma Zone and Peripapillary Hyperreflective Ovoid Mass-Like Structures in Non-Pathological Highly Myopic Eyes.

Purpose: To investigate the prevalence and risk factors of enlarged blind spots in non-pathological highly myopic eyes. Methods: Visual field conditions of 313 eyes in 172 individuals with high myopia were evaluated. Clinical characteristics of 116 eyes with enlarged blind spots and 116 eyes with normal visual fields were compared. Generalized-estimating equation (GEE) regression model were used to assess the factors associated with enlarged blind spots. Results: The frequency of enlarged blind spots in non-pathological highly myopic eyes was 37.06% in this sample. Eyes with enlarged blind spots had larger gamma zone (P = 0.038), larger PHOMS area (P < 0.001), increased peripapillary retinal nerve fiber layer thickness (P = 0.006), and decreased macular ganglion cell-inner plexiform layer thickness (P = 0.016) compared with eyes with normal visual fields. In multivariate regression analysis, an expanded gamma zone (OR = 2.004; P = 0.022) and a larger PHOMS area (OR = 4.414; P = 0.009) were associated with an enlarged blind spot. Conclusions: An expanded gamma zone and a larger PHOMS area are associated with an enlarged blind spot, indicating that these two parameters may suggest a possibility of functional damage in early nonpathological, highly myopic eyes. This pattern of impairment might provide clues for the differential diagnosis between high myopia and glaucoma.