Effect of Low Myopia on Near and Distance Vision in Astigmatic Pseudophakic Eyes

Purpose: To investigate the effect of the postoperative spherical equivalent (SE) and astigmatism on the uncorrected near/distance visual acuity (UNVA/UDVA) in monofocal intraocular lens (IOL)-implanted pseudophakic eyes.Methods: Of the eyes that underwent successful cataract surgery and monofocal IOL implantation from January 2020 to September 2021 by a single surgeon, eyes with postoperative astigmatism ≤ 1.5 diopters (D) and -0.75 D ≤ SE < +0.25 D were included. Eyes implanted with a toric IOL or with a best corrected visual acuity under 20/25 were excluded. This was a cross-sectional study, and the correlation of SE/astigmatism and UNVA/UDVA at 1 month postoperatively was analyzed retrospectively. The eyes were divided into mini-myopia (-0.75 D ≤ SE < -0.25 D) and emmetropia (-0.25 D ≤ SE < 0.25 D) groups according to the SE.Results: This study included 118 eyes (86 patients). The UNVA was significantly better in the mini-myopia group than in the emmetropia group (p = 0.009), without a significant difference in UDVA (p = 0.412). Dividing the range into 0.5 D units according to the degree of astigmatism, no significant difference was observed in UNVA/UDVA between the mini-myopia and emmetropia groups in eyes with astigmatism ≤ 1.0 D. However, the mini-myopia group had a significantly better UNVA (p = 0.03), without a significant difference in UDVA (p = 0.879) in eyes with astigmatism > 1.0 D or ≤ 1.5 D.Conclusions: In non-toric monofocal IOL-implanted pseudophakic eyes with postoperative residual astigmatism of ≤ 1.5 D, especially in eyes with astigmatism > 1.0 D and ≤ 1.5 D, the mini-myopia group had a significantly better UNVA compared to the emmetropia group, without a significant difference in UDVA.