Optical performance of toric intraocular lenses in the presence of decentration

Influence of decentration of plate-haptic toric intraocular lens on postoperative visual quality

BACKGROUND

To evaluate the influence of decentration of plate-haptic toric intraocular lens (IOLs) on visual quality.

METHODS

This study enrolled 78 eyes of 78 patients. Patients in group A were implanted with toric IOLs, and patients in group B were implanted with monofocal IOLs. All patients were divided into group A1 and B1 (decentration below 0.3 mm) and group A2 and B2 (decentration above 0.3 mm). The uncorrected distance visual acuity (UDVA), best corrected visual acuity (BCVA), modulation transfer function cutoff (MTF cutoff), objective scatter index (OSI), strehl ratio (SR), optical interference and patients' satisfaction were measured in different pupils at three months postoperatively. The associations between decentration and visual quality were analyzed by Spearman correlation.

RESULTS

There were no significant differences in UDVA, BCVA, MTF cutoff, OSI, SR, optical interference and patients' satisfaction among subgroups. The differences in decentration between groups A and B were not statistically significant. In group A2, the total higher order aberrations (tHOAs) at pupil sizes of 3 mm (P = 0.046), 5 mm (P = 0.014), spherical aberrations at pupil sizes of 3 mm (P = 0.011), 4 mm (P = 0.014), 5 mm (P = 0.000), secondary astigmatism at pupil sizes of 3 mm (P = 0.002), 4 mm (P = 0.005) were higher than in group B2. Compared to group A1, group A2 had higher spherical aberrations at pupil sizes of 4 mm (P = 0.042), 5 mm (P = 0.001), 6 mm (P = 0.038), secondary astigmatism at pupil sizes of 3 mm (P = 0.013), 4 mm (P = 0.005), 6 mm (P = 0.013). Group B2 has higher coma and secondary astigmatism than group B1 at 6-mm pupil (P = 0.014, P = 0.045). Significant positive correlations were found between spherical aberrations and the decentration of group A1 and A2 at 6-mm pupils.

CONCLUSION

The decentration above 0.3 mm negatively affected visual quality due to increased tHOAs, spherical aberrations, coma and secondary astigmatism aberrations, the influence become larger with increasing pupil diameter. And toric IOLs are more affected by decentration than monofocal IOLs.

Tilt and decentration with various intraocular lenses: A narrative review

We find that tilt and decentration of intraocular lens (IOL) commonly cause visual quality deterioration after cataract surgery. Multiple factors affect IOL tilt and decentration in the pre-, mid-, and post-operation phases. Moreover, the tilt and decentration of 1-piece IOL are less correlated with internal ocular HOAs than those of 3-piece IOL. Aspherical IOLs are more sensitive to decentration or tilt than spherical IOLs. Furthermore, the optical performance of toric IOLs with an accurate axis remains stable irrespective of tilt and decentration. The optical quality of asymmetric multifocal IOLs varies significantly after decentration and tilt in different directions. The image quality enhances or deteriorates in the direction of the decentered IOL. An extended depth of focus IOL can achieve good visual acuity in the distant, intermediate, and near range. Additionally, its tilt and decentration have less impact on the vision than bifocal and trifocal IOL. This is the first review that compares the effect of IOL tilt and decentration on image quality for various IOL designs. The result indicates that a deeper understanding of tilt and decentration of various IOLs can help achieve a better visual effect to visually improve refractive cataract surgery.

Effect of decentration, tilt and rotation on the optical quality of various toric intraocular lens designs: a numerical and experimental study

Toric intraocular lenses (T-IOLs) may lose their optical quality if they are not correctly positioned inside the capsular bag once implanted. In this work, T-IOLs with cylinder powers of +1.50, +4.50 and +7.50 D and differing degrees of spherical aberration have been designed, manufactured and tested in vitro using a commercial optical bench that complies with the requirements of standard ISO 11979-2. Moreover, the effect of tilt and rotation on optical quality was assessed by means of numerical ray tracing on an astigmatic eye model, while the effect of decentration was evaluated numerically and experimentally.