Astigmatism induced by intraocular lens tilt evaluated via ray tracing

Weikert, Mitchell P.; Golla, Abhinav; Wang, Li

doi:10.1016/j.jcrs.2018.04.035

Cited by 49 publications

(34 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For instance, horizontal tilt of an aspheric IOL induces against-the-rule astigmatism. For 5° and 10°of IOL tilt, the induced astigmatism levels were 0.14 dioptres (D) and 0.56 D for 28 D aspheric IOLs respectively [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Aspheric IOLs, which are primarily designed to compensate for the corneal positive spherical aberration, are shown to produce more optical quality degradation if tilted or decentred, compared to spherical IOLs [ 17 ]. Expectedly, for toric IOLs, tilt and decentration lead to less predictable astigmatism outcomes [ 16 ]. The alignment and amount of toricity along with orientation of tilt have resulted in under-correction or over-correction of astigmatism in toric IOLs in theoretical eye models [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Expectedly, for toric IOLs, tilt and decentration lead to less predictable astigmatism outcomes [ 16 ]. The alignment and amount of toricity along with orientation of tilt have resulted in under-correction or over-correction of astigmatism in toric IOLs in theoretical eye models [ 16 ]. In multifocal IOLs, decentration might result in a different light distribution between the distance focus and near focus [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations

Ashena

Maqsood

Ahmed

et al. 2020

Vision

View full text Add to dashboard Cite

Tilt and decentration of intraocular lenses (IOL) may occur secondary to a complicated cataract surgery or following an uneventful phacoemulsification. Although up to 2–3° tilt and a 0.2–0.3 mm decentration are common and clinically unnoticed for any design of IOL, larger extent of tilt and decentration has a negative impact on the optical performance and subsequently, the patients’ satisfaction. This negative impact does not affect various types of IOLs equally. In this paper we review the methods of measuring IOL tilt and decentration and focus on the effect of IOL tilt and decentration on visual function, in particular visual acuity, dysphotopsia, and wavefront aberrations. Our review found that the methods to measure the IOL displacement have significantly evolved and the available studies have employed different methods in their measurement, while comparability of these methods is questionable. There has been no universal reference point and axis to measure the IOL displacement between different studies. A remarkably high variety and brands of IOLs are used in various studies and occasionally, opposite results are noticed when two different brands of a same design were compared against another IOL design in two studies. We conclude that <5° of inferotemporal tilt is common in both crystalline lenses and IOLs with a correlation between pre- and postoperative lens tilt. IOL tilt has been noticed more frequently with scleral fixated compared with in-the-bag IOLs. IOL decentration has a greater impact than tilt on reduction of visual acuity. There was no correlation between IOL tilt and decentration and dysphotopsia. The advantages of aspheric IOLs are lost when decentration is >0.5 mm. The effect of IOL displacement on visual function is more pronounced in aberration correcting IOLs compared to spherical and standard non-aberration correcting aspherical IOLs and in multifocal versus monofocal IOLs. Internal coma has been frequently associated with IOL tilt and decentration, and this increases with pupil size. There is no correlation between spherical aberration and IOL tilt or decentration. Although IOL tilt produces significant impact on visual outcome in toric IOLs, these lenses are more sensitive to rotation compared to tilt.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations

Ashena

Maqsood

Ahmed

et al. 2020

Vision

View full text Add to dashboard Cite

show abstract

“…Factors in uencing residual refractive astigmatism after cataract surgery with toric IOLs include accurate preoperative corneal astigmatism measurements, variability in the magnitude and direc tion of corneal incision SIA, the effects of dif ferent toric calculators, the rotational stability of different toric IOLs [8], and reported lens tilt [9]. Several diagnostic devices based on different technologies are available to measure preoperative corneal power and astigmatism, including manual and automated keratometers; Placidobased corneal, point-source color light emitting diode, Scheimp ug image-based, and scanning-slit corneal topographers; low-coherence re ectometers; and intraoperative aberrometers [10][11][12][13].…”

Section: Discussionmentioning

confidence: 99%

Clinical Evaluation of Toric Intraocular Lens Implantation Based on iTrace Wavefront Keratometric Astigmatism

Zhang

Zhou

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: There was no standard technique for measuring corneal astigmatism. The iTrace wavefront aberrometry of cornea calculated steep power and axis based on the best Zernike mathematical fit from all topo data within 4 mm circle. It was supposed to be more accurate than iTrace simulated keratometry which was calculated based on only 4 points on the circle of 3 mm. This study evaluated visual outcomes, rotational stability after performing toric intraocular lens (IOL) implantation planning based on the wavefront aberrometry of the cornea with iTrace. Setting: Single site in China, Shanxi Eye Hospital, Shanxi, China.Design: Prospective case series.Methods: The study included 85 eyes of 63 patients undergoing phacoemulsification and toric IOL implantation. The IOL power and cylinders were chosen with the help of the iTrace toric planning program using wavefront keratometric astigmatism. Over a 3-month follow-up period, astigmatic changes were assessed using the Alpins vector method. Results: Preoperative mean corneal topographic astigmatism was 1.91 diopters (D) ± 0.69 (standard deviation). Postoperative mean refractive astigmatism decreased significantly to 0.48 D ± 0.34. Surgical induced astigmatism was 1.73 D ± 0.77 and the mean correction index was 0.89 ± 0.22, showing a slight undercorrection. The proportion of astigmatism ≤ 0.50 D increased from 0 to 71.8% postoperatively.Conclusions: This is the first study evaluating the clinical outcomes of using iTrace wavefront keratometric readings to plan a toric IOL implantation. The findings show that the iTrace built-in toric calculator with wavefront keratometric astigmatism for toric IOL planning is safe and effective.Trial registration: Current Controlled Trials ISRCTN94956424, Retrospectively registered (Date of registration: 05 February 2020). http://www.isrctn.com/ISRCTN94956424.

show abstract

“…IOLs [8], and reported lens tilt [9]. Several diagnostic devices based on different technologies are available to measure preoperative corneal power and astigmatism, including manual and automated keratometers; Placido-based corneal, point-source color light emitting diode, Scheimpflug imagebased, and scanning-slit corneal topographers; low-coherence reflectometers; and intraoperative aberrometers [10][11][12][13].…”

Section: Discussionmentioning

confidence: 99%

Clinical Evaluation of Toric Intraocular Lens Implantation Based on iTrace Wavefront Keratometric Astigmatism

Zhang

Zhou

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: There was no standard technique for measuring corneal astigmatism. The iTrace wavefront aberrometry of cornea calculated steep power and axis based on the best Zernike mathematical fit from all topo data within 4 mm circle. It was supposed to be more accurate than iTrace simulated keratometry which was calculated based on only 4 points on the circle of 3 mm. This study evaluated visual outcomes, rotational stability after performing toric intraocular lens (IOL) implantation planning based on the wavefront aberrometry of the cornea with iTrace. Setting: Single site in China, Shanxi Eye Hospital, Shanxi, China. Design: Prospective case series. Methods ： The study included 85 eyes of 63 patients undergoing phacoemulsification and toric IOL implantation. The IOL power and cylinders were chosen with the help of the iTrace toric planning program using wavefront keratometric astigmatism. Over a 3-month follow-up period, astigmatic changes were assessed using the Alpins vector method. Results ： Preoperative mean corneal topographic astigmatism was 1.91 diopters (D) ± 0.69 (standard deviation). Postoperative mean refractive astigmatism decreased significantly to 0.48 D ± 0.34. Surgical induced astigmatism was 1.73 D ± 0.77 and the mean correction index was 0.89 ± 0.22, showing a slight undercorrection. The proportion of astigmatism ≤ 0.50 D increased from 0 to 71.8% postoperatively. Conclusions ： This is the first study evaluating the clinical outcomes of using iTrace wavefront keratometric readings to plan a toric IOL implantation. The findings show that the iTrace built-in toric calculator with wavefront keratometric astigmatism for toric IOL planning is safe and effective.

show abstract

Astigmatism induced by intraocular lens tilt evaluated via ray tracing

Abstract: Tilting aspheric IOLs horizontally around a vertical meridian induced ATR astigmatism. Tilting toric IOLs aligned at 90 degrees increased ATR astigmatism, resulting in overcorrection. Tilting toric IOLs aligned at 180 degrees decreased WTR astigmatism, producing undercorrection.

Cited by 49 publications

References 11 publications

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations

Clinical Evaluation of Toric Intraocular Lens Implantation Based on iTrace Wavefront Keratometric Astigmatism

Clinical Evaluation of Toric Intraocular Lens Implantation Based on iTrace Wavefront Keratometric Astigmatism

Contact Info

Product

Resources

About