Optical bench simulation for intraocular lenses using field-tracing technology

Effect of decentration and tilt on the in vitro optical quality of monofocal and trifocal intraocular lenses

PURPOSE

To evaluate and compare the effect of decentration and tilt on the optical quality of monofocal and trifocal intraocular lenses (IOL).

METHODS

Optical quality of a monofocal IOL (AcrySof IQ SN60WF; Alcon Laboratories, Inc., USA) and a trifocal IOL (AcrySof IQ PanOptix; Alcon Laboratories, Inc., USA) was assessed using an in vitro optical bench (OptiSpheric IOL R&D; Trioptics GmbH, Germany). At apertures of 3.0 mm and 4.5 mm, modulation transfer function (MTF) at spatial frequency of 50 lp/mm, MTF curve and the United States Air Force (USAF) resolution test chart of the two IOLs were measured and compared at their focus with different degrees of decentration and tilt. Optical quality at infinity, 60 cm and 40 cm and the through-focus MTF curves were compared when the two IOLs were centered at apertures of 3.0 mm and 4.5 mm. Spectral transmittance of the two IOLs was measured by the UV-visible spectrophotometer (UV 3300 PC; MAPADA, China).

RESULTS

The SN60WF and the PanOptix filtered blue light from 400 to 500 nm. Both IOLs at the far focus and the PanOptix at the intermediate focus showed a decrease in optical quality with increasing decentration and tilt. The PanOptix demonstrated enhanced optical quality compared to the previous gradient at the near focus at a decentration range of 0.3-0.7 mm with a 3.0 mm aperture, and 0.5 mm with a 4.5 mm aperture, whereas other conditions exhibited diminished optical quality with increasing decentration and tilt at the focus of both IOLs. When the two IOLs were centered, the SN60WF had better optical quality at infinity, while the PanOptix had better optical quality at 60 cm and 40 cm defocus. The optical quality of the SN60WF exceeded that of the PanOptix at far focus, with a 3 mm aperture decentration up to 0.7 mm and a 4.5 mm aperture decentration up to 0.3 mm; this observation held true for all tilts, irrespective of aperture size. As both decentration and tilt increased, the optical quality of the SN60WF deteriorated more rapidly than that of the PanOptix at the far focal point.

CONCLUSIONS

The SN60WF showed a decrease in optical quality with increasing decentration and tilt. Optical quality of the PanOptix at the near focus increased in some decentration conditions and decreased in some conditions, while it showed a decrease at the other focuses with increasing decentration. While tilt only had a negative effect on optical quality. When both IOLs were centered, the PanOptix provided a wider range of vision, while the SN60WF provided better far distance vision. At the far focus, the SN60WF has better resistance to tilt than the PanOptix, but the optical quality degrades more quickly when decentered and tilted.

Influence of a Capsular Tension Ring on Capsular Bag Behavior of a Plate Haptic Intraocular Lens: An Intraindividual Randomized Trial

PURPOSE

To evaluate the influence of a capsular tension ring (CTR) on rotational stability, decentration, tilt, and axial stability of an 11.0-mm plate haptic intraocular lens (IOL).

DESIGN

Intraindividual, randomized, double-masked, controlled clinical trial.

PARTICIPANTS

Patients scheduled for sequential same-day bilateral cataract surgery.

METHODS

All patients were randomized to receive a CTR and a plate haptic IOL in one eye and a plate haptic IOL in the fellow eye only. Intraocular lens axis assessment was performed at the end of surgery, 1 hour, 1 week, 1 month, and 6 months using a high-precision evaluation method. Decentration and tilt of the crystalline and pseudophakic lenses were assessed before surgery and at 1 week and 6 months using an anterior segment OCT.

MAIN OUTCOME MEASURES

Rotational stability from the end of surgery to 6 months and at all follow-up visits, decentration and tilt at 6 months, and differences in axial shift between 1 week and 6 months.

RESULTS

One hundred thirty eyes of 65 patients were included in the study. Absolute rotation from the end of surgery to 6 months was 2.8 ± 3.9° and 3.2 ± 5.3° for the CTR and control groups, respectively (P = 0.613). Intraocular lens decentration and IOL tilt at 6 months were 0.29 ± 0.1 mm and 0.24 ± 0.1 mm and 6.7 ± 2.8° and 5.6 ± 1.6° for the CTR and control groups, respectively (P = 0.058; P < 0.01). A posterior IOL shift of 0.31 ± 0.31 mm and 0.19 ± 0.14 mm was observed in the CTR and control groups, respectively.

CONCLUSIONS

Concomitant implantation of a CTR and a plate haptic IOL did not improve the overall rotational stability of the IOL compared with the control group. Against expectations, higher values of decentration, tilt, and axial shift were observed in the CTR group. The simultaneous use of a CTR and a plate haptic IOL in the absence of zonular weakness at the time of cataract surgery should be considered with caution.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Geometric-phase intraocular lenses with multifocality

We demonstrate a new type of multifocal and extended depth of focus (EDOF) intraocular lenses (IOLs) embedding μm-thin geometric phase (GP) lens layers. As an emerging approach for lens phase design, the GP modulated IOLs outperform conventional diffractive IOLs in multifocality while completely avoiding the clinically undesirable demand for additional surface patterns to standard monofocal IOL designs. The number of foci and light splitting ratio of the GP IOLs are adjusted by changing the number of stacked GP layers and the thickness of each layer. Bifocal and trifocal GP IOLs are fabricated by radial alignment of anisotropic orientation in UV-curable liquid crystal polymers. After characterizing the defocus image and modulation transfer function of the GP IOLs, it is expected that GP IOLs will alleviate the most common problems associated with multifocal and EDOF IOLs, blurred vision and photic phenomena caused by light scattering and posterior capsule opacification.