Objective To study asphericity in the horizontal direction of the anterior corneal surface in high myopia. Methods This was a retrospective case series study. The corneal topographies of 38 cases (right eyes) with high myopia were collected from the Orbscan Ⅱ topography system and the data of the anterior corneal surface in the tangential map were filtered out. The Q-values of the 360 semi-meridians were calculated by linear regression using the tangential radius in corneal topography and the coordinate rotation technique. The data in the range of ±45° around the horizontal principal meridian were then studied. The Q-values of the semi-meridians in intervals of 15° from the principal meridian were selected (the semi-meridians of 315°, 330°, 345°, 0°, 15°,30° and 45° on the nasal side; 135°, 150°, 165°, 180°, 195°, 210°, 225° on the temporal side).The average Q-values of the quadrants of all 15 semi-meridians were calculated (the quadrants of 315°-329°, 330°-344°, 345°-359°, 1°-15°, 16°-30°, 31°-45° on the nasal side; 135°-149°,150°-164°, 165°-179°, 181°-195°, 196°-210°, 211°-225° on the temporal side). All the subjects were divided into two groups according to equivalent refractive power: high myopia group (-6.00-9.00 D,26 cases); ultra-high myopia group (over -9.00 D, 12 cases). Then an independent samples t test was used to compare the differences between the two groups. Results The Q-values of the selected semi-meridians in the horizontal direction: the nasal side, 315° was -0.17±0.05, 330° was -0.22±0.06, 345° was -0.30±0.09, 0° was -0.36±0.08, 15° was -0.37±0.10, 30° was -0.32±0.09, 45°was -0.26±0.10; the temporal side, 135° was -0.26±0.11, 150° was -0.34±0.12, 165° was -0.36±0.12, 180° was -0.38±0.12, 195° was -0.41±0.12, 210° was -0.40±0.10, 225° was -0.36±0.11.The average Q-values of the quadrants: the nasal side, 315°-329° was -0.19±0.05, 330°-344° was -0.26±0.08, 345°-359° was -0.33±0.09, 0° was -0.36±0.08, 1°-15° was -0.37±0.08, 16°-30° was -0.34±0.09, and 31°-45° was -0.30±0.10;the temporal side, 135°-149° was -0.30±0.11, 150°-164°was -0.35±0.11, 165°-179° was -0.37±0.12, 180° was -0.38±0.12, 181°-195° was -0.40±0.11,196°-210° was -0.41±0.11, and 211°-225° was -0.38±0.11. The average Q-values of the quadrants (15° on eac side around the horizontal meridian) for the high myopia group: the nasal side was -0.34±0.09 and the temporal side was -0.35±0.12; for the ultra-high myopia group: the nasal side was -0.31±0.08 and the temporal side was -0.34±0.13. The differences between the two groups (the nasal side: t=-1.058, P=0.297; the temporal side: t=-0.162, P=0.873) were not statistically significant.Conclusion The horizontal direction of the anterior corneal surface is a prolate ellipsoid. This means it becomes gradually flatter from the central to perimeter zone, and the trend declines gradually from the horizontal to oblique meridian. The influence of refractive power on asphericity is quite weak.