Clinico-pathological results of optical quality with different

acrylic materials

Mayank A. Nanavaty, DO, MRCOphth, MRCS(Ed)

David J. Spalton, FRCP, FRCS, FRCOphth

James F. Boyce, PhD

Thomas J. T. P. Van den berg, PhD

St. Thomas’ Hospital, London

None of the authors have any financial or proprietary interest

Introduction• Optical quality of vision is dependent on aberrations,

PSF, MTF and ocular scatter apart from visual acuity.

• There is paucity of information on influence of IOL material on optical quality

• One published study objectively quantifying the relationship between IOL material and ocular scatter

Tanaka et al. Limitation of Scheimpflug videophotography system in quantifying posterior capsule

opacification after intraocular lens implantation. Am J Ophthalmol 2004 Apr;137(4):732-5.

Aim

To analyze the effect of IOL material on optical quality in eyes

with clear posterior capsules using the asymmetric double pass technique with

Optical Quality Analysis System (OQAS II)

Methods• Retrospective, non-randomized, observational study

• Patients with clear posterior capsule were recruited from the follow up of two different ongoing prospective, randomized fellow eye controlled studies comparing

• Hydrophilic - AcriSmart 36A & Akreos MI60• Hydrophobic - AcrySof IQ & AcrySof Natural

• Single surgeon with standardized surgical technique

AcriSmart 36A Akreos MI60

AcrySof IQ AcrySof Natural

Hydrophobic IOLs

Hydrophilic IOLs

Eyes with clear capsule in central 4mm zone on POCOman analysis of digital retro-illumination images

were recruited

Methods• Data of:

• 100% & 9% LogMAR BCVA

• Entire eye aberrations at 4mm scan size

• 50% & 10% PSF, MTF and Strehl ratio after correcting LOA

was extracted for these eyes with clear posterior capsules

• Two 20D IOLs of each IOL type was sent for in-vitro analysis of light scatter

Results• 160 eyes of 80 patients were screened• 71 eyes of 46 patients had clear capsules• 58 were white Caucasians, 9 Afro-Caribbean, 2 Indians, 2 Mongolians

Hydrophilic IOLs[mean ± standard

deviation (95% confidence interval)]

(n=28)

Hydrophobic IOLs [mean ± standard

deviation (95% confidence interval)]

(n=43)

p values*

Postoperative duration (days)

127.7 ± 41.2(122.3, 133.0)

342.6 ± 65.6(335.7, 349.4)

0.000¥

IOL power (diopters) 19.75 ± 5.20(19.07, 20.43)

21.13 ± 4.02(20.71, 21.55)

0.240

Postoperative Spherical Equivalent (Diopters)

-0.19 ± 0.60 (-0.27, -0.11)

-0.10 ± 0.59 (-0.16, -0.04)

0.534

*Unpaired two tailed t test, ¥ Statistically significant, p < 0.05, BCVA = Best corrected visual acuity,

• No significant difference in aberrations at 4 mm scan size except Zernicke’s polynomial 4 (defocus)

Best corrected visual acuity

Hydrophobic Acrylic Hydrophilic Acrylic

100% LogMAR 9% LogMAR

-0.2

0.0

0.2

0.4

0.6

Lo

gM

AR

p = 0.127

p = 0.000

OQAS II measurements

Optical Quality analysis system (OQAS II)

Measurements done after correcting sphere and cylinder

50% PSF 10% PSF 0

10

20

30

40

PS

F V

alu

e (

arc

min

)

p = 0.008

p = 0.005

Hydrophobic Acrylic Hydrophilic Acrylic

There was no significant difference in MTF and Strehl ratio between to the two IOL groups

PSF measurements

In-vitro assessment of scatter

Although in-vitro scatter levels are low with acrylic IOLs, hydrophilic acrylic IOLs have more scatter than hydrophobic acrylic IOLs

-1

-0.5

0

0.5

1

1.5

2

-25 -20 -15 -10 -5 0 5 10 15 20 25

scatter angle (degrees)

log

str

ayli

gh

t p

aram

eter

hydrophilic

hydrophobic

young eyes

good 77y old

cataract (10x)

young eye (1x)

good 77 old eye (3x)

cataract (10x)

Conclusion

• IOL material has no effect on 100% BCVA, entire eye aberrations, MTF and Strehl ratio

• Hydrophilic Acrylic IOLs have reduced 9% LogMAR BCVA

• Ocular scatter is more with hydrophilic Acrylic IOLs

• This may be because of increased opalescence of the hydrophilic acrylic material due to more water content