What’s all this talk about aspheric IOLs?

Con MoshegovDept of Ophthalmology Meeting

CRGH October 2, 2007.

Cataract surgery: patient expectations

• Whether implanted with monofocal or multifocal IOLs patients can have problems with the quality of vision

• Poor vision at night, glare, halos, dysphotopsias not to mention gripes independent of the IOL choice

• IOL technology has improved to maximise quality of vision

• Many surgeons prefer to keep things just as they are

20/20 ?

Quality of Vision?

Contrast Sensitivity is a better test of functional vision than Visual Acuity!

Sinewave contrast sensitivity is the most widely accepted test of contrast sensitivity

It is more specific and sensitive than ETDRS, Pelli-Robson tests

Contrast Sensitivity

The more cycles per degree the patient can see the better the contrast sensitivity.

• Many things reduce contrast sensitivity– Optical error

• Lower order aberrations: sphere and cylinder• Higher order aberrations: not correctable with

glasses

– Ocular pathology– Age– (Possibly) cataract surgery

Reduces contrast sensitivity and increases glare sensitivity…

Spherical Aberration

…especially at night when the pupil is large

Provides a description of the entire optical error of the eye

Wavefront Aberrometry

• Spherical lenses do not focus parallel light rays exactly on one point. • Positive spherical aberration results when the refractive power in the periphery is too strong. • Negative spherical aberration results when the refractive power in the periphery is too weak.• The resulting image is less clear and has less contrast

Spherical Aberration

Negative Spherical AberrationPositive Spherical Aberration

Spherical aberration of the cornea

positive spherical aberration

The cornea of a young eye has positive spherical aberration which is neutralised by the negative spherical aberration of the lens.

The Young Eye

Spherical Aberration in Human Eyes

• Healthy subjects from 20 to 70 years of age. • Overall aberrations increase by a factor of 3 with

age.• Corneal aberrations change only moderately.• Applies to all higher-order aberrations such as

coma, trefoil etc

Artal, Berrio, Guirao, Piers (2002) J.Opt.Soc.Am.A.Opt.Image Sci.Vis. 19(11): 137-143

Changes over a lifetime

Age 25 30 35 40 45 50 55 60 65 70

mic

ron

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0.0

0.2

0.4

0.6

0.8

1.0

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Wavefront Aberrations of the Eye Increase with Age

Guirao A, Artal P. Corneal wave aberration from videokeratography: accuracy and limitations of the procedure. J Opt Soc Am A Opt Image Sci Vis. 2000;17:955-65.

Wavefront Aberrations of the Cornea Remain

Relatively Constant with Age

Guirao A, Artal P. Corneal wave aberration from videokeratography: accuracy and limitations of the procedure. J Opt Soc Am A Opt Image Sci Vis. 2000;17:955-65.

Glasser A, Campbell MC. Vision Res. 1998;38:209-29.

Spherical Aberration of the Natural Human Lens

Contrast Sensitivity Decreases with Age

Aging of the lens

Young Old

“The lens grows over a lifetime - and in doing so, changes its curvature. ”(Brown, 1974)“The Lens becomes thicker …” (Koretz et al, 1989)“The refractive index of the lens changes …” (Smith et al, 1992)

Spherical Aberrations in Human Eyes

The positive spherical aberration of the mature cornea is no longer neutralised as the lens also has a positive spherical aberration.

The Mature Eye

Standard IOLs increase aberrations

Aberrations of cornea and standard IOLs

Aspheric IOL: Tecnis

Conventional IOLs Tecnis

T E C N I S Z-SHARPOPTIC TECHNOLOGY

A New IOL for Better Vision!

-0.04

-0.02

0

0.02

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0.06

0.08

0.1

0.12

1 month 3 months

Z(4

,0)

µm

SI40 Tecnis™

Mester et al. Impact of a modified optic design on visual function: Clinical comparative study. J Cataract Refract Surg. 2003; 29:652–660

Total Spherical Aberration1 and 3 months after surgery

Photopic Contrast Sensitivity3 months after surgery

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Spatial frequency (c/deg)

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*P < 0.05

Tecnis™ SI40

Mester et al. Impact of a modified optic design on visual function: Clinical comparative study. J Cataract Refract Surg. 2003; 29:652–660

Mesopic Contrast Sensitivity3 months after surgery

Mester et al. Impact of a modified optic design on visual function: Clinical comparative study. J Cataract Refract Surg. 2003; 29:652–660

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*P < 0.05

Tecnis™ SI40

Spatial frequency (c/deg)

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1.5 3 6 12 18

• Long straight street • Simulated speed 35 miles/h• High degree of ambient light

• Long straight road • Simulated speed 55 miles/h• Minimum ambient light (low

beam auto headlights)

City Driving Scene Rural Driving Scene

Night Driving Simulation

Target detection and identification

Object Detection: Tecnis™ significantly better than control

Data on file. AMO.

Night Driving Simulation

With Tecnis™ and at 55 mph, patients identify a pedestrian (rural setting/glare) at 486 feet versus 441 feet for the standard IOL (p=0.0011)

Increased reaction time Safer stopping

Data used in FDA submission for recognition of special status

Improved functional vision with a modified prolate intraocular lens. Packer M, Fine IH, Hoffman RS, Piers PA. J Cataract Refract Surg. 2004 May;30(5):986-92.

Methods: Patients randomly assigned to receive a Tecnis Z9000 IOL (Pfizer) or a Sensar OptiEdge AR40e IOL (AMO) in 1 eye were followed for 3 months postoperatively

Conclusion: Results show the Tecnis IOL with a modified prolate anterior surface produces better contrast sensitivity than a standard spherical IOL under mesopic and photopic conditions.

15 Patients per group/ 3 months follow up

TECNIS Z9000 Studies

AcrySof IQ (SN60WF) IOL

Adds -0.20 µm spherical aberration.

Tecnis Z9000 IOL

Adds -0.27 µm spherical aberration.

B&L LI61AO/AOV IOL

Source: Package Inserts, Data on File

Adds 0.00 µm spherical aberration.

Aspheric IOLs

a Laboratory data on file. Alcon Laboratories, Inc.b Holladay et al., A new intraocular lens design to reduce spherical aberration of pseudophakic eyes. JCRS 2002; 18:683-691.c Mester et al., Impact of a modified optic design on visual function: clinical comparative study. JCRS 2003; 29:652-660.d Altmann et al., Optical performance of 3 intraocular lens designs in the presence of decentration. JCRS 2005; 31:574-585.

6.0 mm

Pupil Size

Lens Spherical Aberration

(µm)

Overall Spherical Aberration (µm)

AcrySof IQ −0.20a ~0.1a

Tecnis −0.27b ~ 0.00c

SofPort AO 0.00d ~ 0.28d

Residual Spherical AberrationFigures in µm

SA

Lens

Cornea

1. Artal et al. Journal of Vision 2001; 1:1-8.2. Levy et al. AJO 2005; 139:225-228.3. Legras R, Chateau N, Charman WN. Assesment of Just-noticeable differences for refractive errors and

spherical aberration using visual stimulation. Opt Vis Science (81)9 718-728.4. Glasser A, Campbell MCW. Vision Res 1998; 38:209–2295. Holladay et al. J of Refract Surg 2002; 18:683-691.6. Wang L,, et al. Higher order aberrations from the internal optics of the eye. JCRS 2005;31.

AcrySof IQ

AO / AOVTecnis

+0.074+0.2750.0

-0.2000-0.274

0.2740.2740.274

65 yrs20 yrs

+0.174+0.094

-0.100-0.180

0.2740.274

AcrySof® IQ (SN60WF)

• Material: AcrySof® with UV and blue light-filtering chromophores

• Haptic Type: STABLEFORCE® Modified-L• Optic Diameter: 6.0 mm• Overall Length: 13.0 mm• Refractive Index: 1.55• Special Feature: Posterior Aspheric Surface• Diopter Range: +6.0D to +30.0D• A-Constant: 118.7

AMO

AcrySof IQ IOL

Aspheric IOL Profiles

Actual digital photos of 20D lens comparisons

Equally powered AcrySof Natural IOL

B&L

AcrySof IQ SN60WF - New Clinical Data*

Controlled, randomized, double-masked, multicenter contralateral implant study of the AcrySof® IQ IOL versus a spherical control lens demonstrated the following:

•Ocular spherical aberrations statistically significantly less in AcrySof® IQ eyes vs. the control lens (SA60AT).•Statistically significant improvement in contrast sensitivity in eyes implanted with the AcrySof® IQ lens vs. control.•Functional vision improvement statistically significant based on simulated night driving, vs. control, especially in glare and fog.

*FDA Approval in U.S. for New Clinical Data Claims for AcrySof IQ SN60WF IOL vs. monofocal spherical control lens. (April 2007)

Clinical patient benefits:SN60WF (IQ) vs. SA/SNAT

Better Contrast Less spherical aberration

IOL models with asphericity are multiplying

• B&L Acryos

• B&L Sofport

• B&L MIL60

• AMO Tecnis (silicone)

• AMO Tecnis Acrylic

• AMO Tecnis CL

• Alcon IQ

What if?

• The IOL is tilted?• The IOL is decentred?• The SE is wrong?

Tilting

Ammetropia

Ammetropia

• Glasses will still give better vision than with a standard IOL

Conclusions• IOL technology is getting better and translates into

practically significant improvements in vision

• Aspheric IOLs give most patients a chance at better vision

• Many CRGH patients could benefit from aspheric IOLs

• Optimal results would be achieved if we paid more attention to:

• Pre-operative biometry

• IOL calculation formulae

• Phaco techniques

• Attention to refractive outcomes