title: Optical performance of toric intraocular lenses in the presence of decentration.
abstract: OBJECTIVE
  To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned.
  
  
  METHODS
  Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance.
  
  
  RESULTS
  Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs.
  
  
  CONCLUSIONS
  Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Bin
authors: B
authors: Zhang
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Jin-Xue
authors: JX
authors: Ma
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Dan-Yan
authors: DY
authors: Liu
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Ying-Hua
authors: YH
authors: Du
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Cong-Rong
authors: CR
authors: Guo
authors: Department of Ophthalmology, the Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei Province, China.
authors: Yue-Xian
authors: YX
authors: Cui
keywords: artificial; astigmatism; cornea; decentration; lens; model