Evaluation of Higher Order Aberrations in Eyes with Evaluation of Higher Order Aberrations in Eyes with Dohlman/Boston Keratoprosthesis and Comparison Dohlman/Boston Keratoprosthesis and Comparison

with Penetrating Keratoplasty and Normal Eyeswith Penetrating Keratoplasty and Normal Eyes

K.StasiK.Stasi11, S.Pantanelli, S.Pantanelli22, R.Sabesan, R.Sabesan22, G.Yoon, G.Yoon22, G.J. McCormick, G.J. McCormick1 1 andandJ.V. AquavellaJ.V. Aquavella11. .

11Dept of Ophthalmology, University of Rochester Eye Institute, Rochester, NY; Dept of Ophthalmology, University of Rochester Eye Institute, Rochester, NY; 22Center for Visual Sciences, University of Rochester, Rochester, NY. Center for Visual Sciences, University of Rochester, Rochester, NY.

Financial Interest Disclosure: K.Stasi, none; S.Pantanelli, none; R.Sabesan, none; G.Yoon, Baush and Lomb; G.J. McCormick, none; J.V. Aquavella, none.

PURPOSE

To evaluate:

• the optical quality of Dohlman/ Boston Keratoprosthesis (KPro) Type I before and after implantation by measuring higher order aberrations

• how the optical quality of KPro compares to normal eyes and eyes after penetrating keratoplasty

INTRODUCTION The Dolman/ Boston keratoprosthesis (KPro) is an artificial cornea PMMA device, alternative to penetrating keratoplasty (PK) with good anatomic results and quick visual recovery, reserved usually for failed PK patients. KPro patients can have good visual acuity and visual fields (according to their visual potential) as well as very good visualization of the fundus.

The wavefront aberrations through this device have not been reported or compared to PK patients or normal subjects. It is also not known how the routine use of bandage contact lens on KPro eyes affects the quality of their vision.

The quality of vision can be evaluated with measuring wavefront aberrations (deviation from ideal eye) which include:

lower (second) order aberrations (like sph/cyl, correctable w. glasses or CLs, 85% of total normal eye aberrations) and

higher order aberrations (not correctable w. glasses or CLs, about 15% of total aberrations)

Abnormal eyes such as PK and KCN eyes as well as symptomatic post-LASIK eyes have significantly more higher-order aberrations (HOAs) than normal eyes.

3rd

4th

5th

Phaseadvance

Phasedelay

Higher-order aberrations

(not correctable w.

Rx, ~15%)

0Defocus

Vertical Coma

Horizontal Coma

Trefoil Trefoil

Spherical Aberratio

n

Secondary Astigmatis

m

Secondary Astigmatis

m

Quadrafoil Quadrafoil

Lower-order aberrations (sph/cyl, correctable w.

Rx, ~85%)

Astigmatism

Pentafoil PentafoilSecondary Coma

Secondary Coma

Secondary Trefoil

Secondary Trefoil

Zernike Pyramid

2nd

Order aberration

Mathematical description of wavefront aberrations: Zernike polynomials

METHODS A Shack-Hartmann large dynamic-range wavefront sensor was used to measure A Shack-Hartmann large dynamic-range wavefront sensor was used to measure higher order aberrations in the following three groups:higher order aberrations in the following three groups:

(I) KPro devices (n=3) mounted to custom made plastic stand

(II) Patients implanted with KPro (n=5), with and without bandage soft contact lens, after dilation (1% tropicamide)

(III) Patients after Penetrating Keratoplasty (n=14) and normal pre-LASIK eyes (n=378) wavefront aberration data were adjusted for a 3mm pupil in order to be comparable to Kpro data (3mm is the optical zone of this

The higher order aberration root mean square (HORMS) was calculated up to the 5th order aswell as the mean and st. deviationof absolute values of each aberration.

Lenslet array

Pupil camera

RESULTS Keratoprosthesis (Kpro) deviceKeratoprosthesis (Kpro) device

HORMS of HORMS of KPro devicesKPro devices (n=3) was (n=3) was 0.11 0.11 ± ± 0.01μm 0.01μm (average ± standard deviation)(average ± standard deviation)

HORMS of HORMS of normal pre-LASIK eyesnormal pre-LASIK eyes with uncorrected visual acuity between 20/30 and 20/100 had a HORMS of 0.05 ± ± 0.02 μm. (for 3mm pupil, n=378).(for 3mm pupil, n=378).

The difference between Kpro and normal eye group was The difference between Kpro and normal eye group was 0.06 μm. This difference is clinically insignificant 0.06 μm. This difference is clinically insignificant (approximately equivalent to 0.17 Diopters of sphere).(approximately equivalent to 0.17 Diopters of sphere).

Kpro patientsKpro patientsFive patients implanted with Dolman/ Boston keratoprosthesis with uncorrected visual acuity between 20/30 and 20/60 wearing plano bandage soft contact lens (BCL).

Patient #1: slit lamp photo at postop day 1 and fundus photo at postop day 4.

Keratoprostheses and Penetrating Keratoplasty Patients: Keratoprostheses and Penetrating Keratoplasty Patients: HORMS, second order RMS HORMS, second order RMS (mean+SD) and uncorrected visual (mean+SD) and uncorrected visual acuity (UCVA)acuity (UCVA)

HORMSHORMS((μμm)m) 2ndRMS2ndRMS((μμm)m) UCVAUCVAKPro ptsKPro pts (n=5) (n=5)with plano BCL with plano BCL 0.30±0.16 0.30±0.16 0.830.83±±0.930.93 20/25-20/6020/25-20/60without BCLwithout BCL 0.360.36±±0.180.18 0.470.47±±0.460.46

PK ptsPK pts (n=14) (n=14) 0.280.28±±0.130.13 1.101.10±±0.260.26 20/30-20/20020/30-20/200

NormalNormal (n=378)(n=378) 0.050.05±±0.020.02 1.051.05±±0.490.49 20/30-20/10020/30-20/100

For 3mm pupil, Kpro eyes had similar higher order aberrations to PK patients but less second order aberrations than PK and normal pre-LASIK eyes by approximately 0.5μm, clinically equivalent to about 1.6 Diopters of sphere

0

0.5

1

1.5

Kpro pts w . BCL (n=5) Kpro pts w /o BCL (n=5) PK pts (n=14) Normal ey es (n=378)

RM

S w

avef

ron

t er

ror

(um

) HORMS

2nd RMS* p= 0.02 t-test Kpro pts and PK pts second order RMS*

Wavefront aberrations in Kpro pts (3mm pupil)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Astig

Defoc

usAsti

g

Trefo

il

Coma

Coma

Trefo

il

Quadr

afoi

l

2nd

Astig

Spher

ical A

b

2nd

Astig

Quadr

afoi

l

Penta

foil

2nd

trefo

il

2nd

com

a

2nd

com

a

2nd

trefo

il

Penta

foil

Wa

ve

fro

nt

err

or

(um

) w. BCL

w/o BCL

Pupil Size (mm)

Hig

her

Ord

er R

ms

Wav

efro

nt E

rror

(μ

m)

K pro Pts

All Symptomatic LASIK

Normal Non-Surgical

n=33 n=32 n=31 n=26

*McCormick et al. Higher Order Aberrations in Symptomatic Eyes with Irregular Corneas After Laser Refractive Surgery. Ophthalmology. 112(10):1699-709, 2005 Oct.

Higher Order aberrations increase with increasing pupil size

Comparison of higher order aberrations from Kpro patients with 3mm optical zone to 6mm pupil data from PK, symptomatic and asymptomatic postLASIK patients, keratoconic and normal eyes.

Higher Order RMS (6mm and 3mm Pupil)

0

0.5

1

1.5

2

2.5

3

3.5

PenetratingKeratoplasty

(n=14)

Keratoconus(n=19)

Symptomatic PostLASIK (n=25)

Normal LASIK(n=46)

Normal PreLASIK Eyes

(n=378)

Normal eyes,3mm pupil(n=378)

Kpro pts w. BCL,3mm pupil (n=5)

PK pts, 3mm pupil(n=14)

RM

S W

avef

ront

Erro

r (µm

)

6mm 3mm

data for 6mm pupil

data for 3mm pupil

CONCLUSIONS It is possible to use wavefront technology to It is possible to use wavefront technology to objectively measure the optical quality of objectively measure the optical quality of keratoprostheses both in vitro and in vivo. To our keratoprostheses both in vitro and in vivo. To our knowledge, a Kpro device has never been knowledge, a Kpro device has never been evaluated this way. evaluated this way.

Higher order aberrations of the Dohlman/Boston Higher order aberrations of the Dohlman/Boston keratoprosthesis Type I were clinically similar to keratoprosthesis Type I were clinically similar to that of eyes after PK. The eyes with Kpro had that of eyes after PK. The eyes with Kpro had significantly smaller residual refractive errors significantly smaller residual refractive errors compared to the PK eyes. compared to the PK eyes.

Research supported in part by a grant from Research to Prevent Blindness