Purpose To evaluate the effect of pupil size on higher-order aberrations (HOAs) in highmyopic pseudophakic eyes with posterior staphyloma using KR-1W aberrometer. Methods Forty eyes of 40 high-myopic cataract patients with posterior staphyloma and 20 eyes of 20 age-related cataract patients with normal axial length were recruited. At 1 month after phacoemulsification and intraocular lens implantation, ocular and internal HOAs as well as the visual quality data in the two groups were evaluated with KR-1W analyzer before and after mydriasis. Results Compared with normal axial length eyes, high-myopic pseudophakic eyes with posterior staphyloma had significantly lower values of internal coma both under 4-mm and 6-mm pupil sizes (Po0.001 and 0.020), as well as internal total HOAs (Po0.001) and third-order aberrations at 6-mm pupil size (P ¼ 0.018). Statistically significant differences were also found in the variation from 4-to 6-mm pupil sizes for internal coma (P ¼ 0.001), internal third-order aberrations (P ¼ 0.009), internal total HOAs (P ¼ 0.007), and ocular coma aberrations (P ¼ 0.006) between two groups. After mydriasis, Strehl ratio increased significantly in high-myopic eyes, whereas decreased slightly in normal axial length eyes (P ¼ 0.032 when compared with the variation between the two groups). Statistically significant differences were also found for the variation of modulation transfer functions (MTFs) at frequencies of 15, 30, 45, and 60 cycles/degree between the two groups (P ¼ 0.002, 0.002, 0.004, and 0.010, respectively).Conclusions High-myopic pseudophakic eyes with posterior staphyloma had significantly lower internal coma and less coma variations during mydriasis.