A Fellow Eye Comparison of Aberrations, Modulation Transfer Function and Contrast

Sensitivity After AcrySof IQ and AcrySof Natural IOL Implantation.

Mayank A. Nanavaty, David J. Spalton,

James F. Boyce, John Marshall

St. Thomas’ Hospital, London

MAN: Honorarium from Alcon Laboratories.

DJS, JFB, JM: Consultant to Alcon Laboratories.

Introduction

•With advances in IOL design and cataract surgery success should be determined by improvement in optical and visual quality rather than just visual acuity.

•Optical quality of vision can be measured by point spread function (PSF) and from this, aberrations and modulation transfer function (MTF) can be derived.

•Contrast sensitivity depends both on the quality of the optical system and also relies on retinal and cortical processing.

•Thus, the quality of vision can be assessed in-vivo by evaluating modulation transfer function, aberrations and contrast sensitivity.

Aims of this study

To compare the optical and visual outcomes in-vivo of a spherical and an aspherical IOL in a fellow eye controlled, prospective, randomized

trial using modulation transfer function, aberrations and contrast sensitivity

Material and Methods

Prospective, randomized, fellow eye controlled study of patients with uncomplicated age-related bilateral cataracts.

All the surgeries performed with standardized technique by a single surgeon.

94 eyes of 47 patients received either an aspheric IOL (AcrySof IQ) or a spherical IOL (AcrySof Natural) in the first eye and the other IOL in the second eye within three weeks.

Postoperative observations• Patients followed up at 1, 3 and 6 months postoperatively

• 100% and 9% EDTRS LogMAR BCVA assessed

• Functional assessment of contrast vision (FACT) measurements done at 3 and 6 months on OPTEC 6500®

under photopic (85 cd/m2) and mesopic condition (3 cd/m2) without glare at patients natural pupil size.

• At 3 and 6 months PSF and corneal topography were performed with the iTrace Dynamic Laserefraction with Vista attachment (Tracey technologies, Houston, USA) after dilatation of pupils.

• The wavefront maps were analyzed for a pupil scan size of 5 mm and up to 6th order of Zernike coefficients.

• MTF was calculated by the software from the PSF.

Results

• Preop K readings, axial length, IOL power, p value = ns

• Corneal Q values at 1 month, p value = ns

• Postop spherical equivalent, p value = ns

• 100% and 9% LogMAR BCVA at 1,3 and 6 months, p value = ns

Higher order aberrations

Total aberrations

MTF due to HOA at 3 months

0.0000.100

0.2000.300

0.4000.500

0.6000.700

0.8000.900

1.000

5 10 15 20 25 30

Cycles/degree

MT

F AcrySof IQ

AcrySof SN

MTF due to HOA at 6 months

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

5 10 15 20 25 30

Cycles/degree

MT

F AcrySof IQ

AcrySof SN

MTF

*

3 months

6 months

*

***

*

*

*

***

*

* P value <0.05

Total MTF at 6 months

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

5 10 15 20 25 30

Cycles/degree

MT

F AcrySof IQ

AcrySof SN

**

* ** *

Total MTF at 3 months

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

5 10 15 20 25 30

Cycles/degree

MTF

AcrySof IQ

AcrySof SN

**

* ** *

Mesopic contrast

sensitivity at 3 cd/m2

Photopic contrast sensitivity at 3 months

0

20

40

60

80

100

120

140

1.5 3 6 12 18

Cycles/degree

Con

trast

Sen

sitiv

ity

AcrySof IQ

AcrySof SN

Mesopic contrast sensitivity at 3 months

0

20

40

60

80

100

120

140

1.5 3 6 12 18

Cycles/degree

Contr

ast

sensitiv

ity

AcrySof IQ

AcrySof SN

**

*

Mesopic contrast sensitivity at 6 months

0

20

40

60

80

100

120

140

1.5 3 6 12 18

Cycles/degree

Con

tras

t se

nsiti

vity

AcrySof IQ

AcrySof SN

**

*

Photopic contrast sensitivity at 6 months

0

20

40

60

80

100

120

140

1.5 3 6 12 18

Cycles/degree

Co

ntr

ast

se

nsitiv

ity

AcrySof IQ

AcrySof SN

Photopic contrast

sensitivity at 85 cd/m2

* P value <0.05

Spherical Aberration Z4(0)

Vertical Coma Z3(-1)* * *

Entire eye Z4(0) at follow up visits with 5 mm pupil

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

1 month 3 months 6 months

Follow up visits

RM

S AcrySof IQ

AcrySof Natural

* * *

Entire eye Z3(-1) at follow up visits

-0.500

-0.400

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

1 month 3 months 6 months

Follow up visits

RM

S

AcrySof IQ

AcrySof Natural

* * *

* P value <0.05

Summary

• MTF is consistently better with AcrySof IQ at all frequencies.

• AcrySof IQ gives better mesopic contrast sensitivity at 3, 6 and 12 cycles/degree.

• Entire eye spherical aberration is always less with AcrySof IQ (mean RMS difference was 0.15µm, 0.2µm and 0.21µm at 1, 3 and 6 months).

• Entire eye vertical coma Z3(-1) aberration was significantly more negative with AcrySof Natural at all follow up visits.

Conclusion

• No change in BCVA between IOLs

• Better mesopic contrast sensitivity with the aspheric lens

• MTF always better with aspheric IOL

• Vertical coma reduced with aspheric lens